From f2ea461e9e9fa5c47bb61fd72d512c748928badc Mon Sep 17 00:00:00 2001
From: =?utf8?q?=C5=81ukasz=20Langa?= <lukasz@langa.pl>
Date: Sat, 8 May 2021 11:29:47 +0200
Subject: [PATCH 1/1] Refactor `src/black/__init__.py` into many files (#2206)
* Move string-related utility to functions to strings.py, const.py
* Move Leaf/Node-related functionality to nodes.py
* Move comment-related functions to comments.py
* Move caching to cache.py and Mode/TargetVersion/Feature to mode.py
* Move some leftover functions to nodes.py, comments.py, strings.py
* Add missing files to source list for test runs
* Move line-related functionality into lines.py, brackets into brackets.py
* Move transformers to trans.py
* Move file handling, output, parsing, concurrency, debug, and report
* Move two more functions to nodes.py
* Add CHANGES
* Add numeric.py
* Add linegen.py
* More docstrings
* Include new files in tests
Co-authored-by: Jelle Zijlstra <jelle.zijlstra@gmail.com>
---
CHANGES.md | 6 +
src/black/__init__.py | 6394 ++------------------------------------
src/black/brackets.py | 334 ++
src/black/cache.py | 83 +
src/black/comments.py | 269 ++
src/black/concurrency.py | 39 +
src/black/const.py | 4 +
src/black/debug.py | 48 +
src/black/files.py | 241 ++
src/black/linegen.py | 984 ++++++
src/black/lines.py | 734 +++++
src/black/mode.py | 123 +
src/black/nodes.py | 843 +++++
src/black/numerics.py | 65 +
src/black/output.py | 83 +
src/black/parsing.py | 215 ++
src/black/report.py | 100 +
src/black/rusty.py | 28 +
src/black/strings.py | 216 ++
src/black/trans.py | 1925 ++++++++++++
tests/test_black.py | 43 +-
tests/test_format.py | 30 +-
tests/util.py | 19 +-
23 files changed, 6586 insertions(+), 6240 deletions(-)
create mode 100644 src/black/brackets.py
create mode 100644 src/black/cache.py
create mode 100644 src/black/comments.py
create mode 100644 src/black/concurrency.py
create mode 100644 src/black/const.py
create mode 100644 src/black/debug.py
create mode 100644 src/black/files.py
create mode 100644 src/black/linegen.py
create mode 100644 src/black/lines.py
create mode 100644 src/black/mode.py
create mode 100644 src/black/nodes.py
create mode 100644 src/black/numerics.py
create mode 100644 src/black/output.py
create mode 100644 src/black/parsing.py
create mode 100644 src/black/report.py
create mode 100644 src/black/rusty.py
create mode 100644 src/black/strings.py
create mode 100644 src/black/trans.py
diff --git a/CHANGES.md b/CHANGES.md
index b81e6eb..8cbdeca 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,5 +1,11 @@
## Change Log
+### Unreleased
+
+#### _Black_
+
+- Refactor `src/black/__init__.py` into many files (#2206)
+
### 21.5b0
#### _Black_
diff --git a/src/black/__init__.py b/src/black/__init__.py
index e47aa21..c61bc8c 100644
--- a/src/black/__init__.py
+++ b/src/black/__init__.py
@@ -1,167 +1,70 @@
-import ast
import asyncio
-from abc import ABC, abstractmethod
-from collections import defaultdict
from concurrent.futures import Executor, ThreadPoolExecutor, ProcessPoolExecutor
from contextlib import contextmanager
from datetime import datetime
from enum import Enum
-from functools import lru_cache, partial, wraps
import io
-import itertools
-import logging
from multiprocessing import Manager, freeze_support
import os
from pathlib import Path
-import pickle
import regex as re
import signal
import sys
-import tempfile
import tokenize
import traceback
from typing import (
Any,
- Callable,
- Collection,
Dict,
Generator,
- Generic,
- Iterable,
Iterator,
List,
Optional,
Pattern,
- Sequence,
Set,
Sized,
Tuple,
- Type,
- TypeVar,
Union,
- cast,
- TYPE_CHECKING,
)
-from mypy_extensions import mypyc_attr
-from appdirs import user_cache_dir
-from dataclasses import dataclass, field, replace
+from dataclasses import replace
import click
-import toml
-
-try:
- from typed_ast import ast3, ast27
-except ImportError:
- if sys.version_info < (3, 8):
- print(
- "The typed_ast package is not installed.\n"
- "You can install it with `python3 -m pip install typed-ast`.",
- file=sys.stderr,
- )
- sys.exit(1)
- else:
- ast3 = ast27 = ast
-from pathspec import PathSpec
+from black.const import DEFAULT_LINE_LENGTH, DEFAULT_INCLUDES, DEFAULT_EXCLUDES
+from black.const import STDIN_PLACEHOLDER
+from black.nodes import STARS, syms, is_simple_decorator_expression
+from black.lines import Line, EmptyLineTracker
+from black.linegen import transform_line, LineGenerator, LN
+from black.comments import normalize_fmt_off
+from black.mode import Mode, TargetVersion
+from black.mode import Feature, supports_feature, VERSION_TO_FEATURES
+from black.cache import read_cache, write_cache, get_cache_info, filter_cached, Cache
+from black.concurrency import cancel, shutdown
+from black.output import dump_to_file, diff, color_diff, out, err
+from black.report import Report, Changed
+from black.files import find_project_root, find_pyproject_toml, parse_pyproject_toml
+from black.files import gen_python_files, get_gitignore, normalize_path_maybe_ignore
+from black.files import wrap_stream_for_windows
+from black.parsing import InvalidInput # noqa F401
+from black.parsing import lib2to3_parse, parse_ast, stringify_ast
+
# lib2to3 fork
-from blib2to3.pytree import Node, Leaf, type_repr
-from blib2to3 import pygram, pytree
-from blib2to3.pgen2 import driver, token
-from blib2to3.pgen2.grammar import Grammar
-from blib2to3.pgen2.parse import ParseError
+from blib2to3.pytree import Node, Leaf
+from blib2to3.pgen2 import token
from _black_version import version as __version__
-if sys.version_info < (3, 8):
- from typing_extensions import Final
-else:
- from typing import Final
-
-if TYPE_CHECKING:
- import colorama # noqa: F401
-
-DEFAULT_LINE_LENGTH = 88
-DEFAULT_EXCLUDES = r"/(\.direnv|\.eggs|\.git|\.hg|\.mypy_cache|\.nox|\.tox|\.venv|venv|\.svn|_build|buck-out|build|dist)/" # noqa: B950
-DEFAULT_INCLUDES = r"\.pyi?$"
-CACHE_DIR = Path(user_cache_dir("black", version=__version__))
-STDIN_PLACEHOLDER = "__BLACK_STDIN_FILENAME__"
-
-STRING_PREFIX_CHARS: Final = "furbFURB" # All possible string prefix characters.
-
# types
FileContent = str
Encoding = str
NewLine = str
-Depth = int
-NodeType = int
-ParserState = int
-LeafID = int
-StringID = int
-Priority = int
-Index = int
-LN = Union[Leaf, Node]
-Transformer = Callable[["Line", Collection["Feature"]], Iterator["Line"]]
-Timestamp = float
-FileSize = int
-CacheInfo = Tuple[Timestamp, FileSize]
-Cache = Dict[str, CacheInfo]
-out = partial(click.secho, bold=True, err=True)
-err = partial(click.secho, fg="red", err=True)
-
-pygram.initialize(CACHE_DIR)
-syms = pygram.python_symbols
class NothingChanged(UserWarning):
"""Raised when reformatted code is the same as source."""
-class CannotTransform(Exception):
- """Base class for errors raised by Transformers."""
-
-
-class CannotSplit(CannotTransform):
- """A readable split that fits the allotted line length is impossible."""
-
-
-class InvalidInput(ValueError):
- """Raised when input source code fails all parse attempts."""
-
-
-class BracketMatchError(KeyError):
- """Raised when an opening bracket is unable to be matched to a closing bracket."""
-
-
-T = TypeVar("T")
-E = TypeVar("E", bound=Exception)
-
-
-class Ok(Generic[T]):
- def __init__(self, value: T) -> None:
- self._value = value
-
- def ok(self) -> T:
- return self._value
-
-
-class Err(Generic[E]):
- def __init__(self, e: E) -> None:
- self._e = e
-
- def err(self) -> E:
- return self._e
-
-
-# The 'Result' return type is used to implement an error-handling model heavily
-# influenced by that used by the Rust programming language
-# (see https://doc.rust-lang.org/book/ch09-00-error-handling.html).
-Result = Union[Ok[T], Err[E]]
-TResult = Result[T, CannotTransform] # (T)ransform Result
-TMatchResult = TResult[Index]
-
-
class WriteBack(Enum):
NO = 0
YES = 1
@@ -182,158 +85,10 @@ class WriteBack(Enum):
return cls.DIFF if diff else cls.YES
-class Changed(Enum):
- NO = 0
- CACHED = 1
- YES = 2
-
-
-class TargetVersion(Enum):
- PY27 = 2
- PY33 = 3
- PY34 = 4
- PY35 = 5
- PY36 = 6
- PY37 = 7
- PY38 = 8
- PY39 = 9
-
- def is_python2(self) -> bool:
- return self is TargetVersion.PY27
-
-
-class Feature(Enum):
- # All string literals are unicode
- UNICODE_LITERALS = 1
- F_STRINGS = 2
- NUMERIC_UNDERSCORES = 3
- TRAILING_COMMA_IN_CALL = 4
- TRAILING_COMMA_IN_DEF = 5
- # The following two feature-flags are mutually exclusive, and exactly one should be
- # set for every version of python.
- ASYNC_IDENTIFIERS = 6
- ASYNC_KEYWORDS = 7
- ASSIGNMENT_EXPRESSIONS = 8
- POS_ONLY_ARGUMENTS = 9
- RELAXED_DECORATORS = 10
- FORCE_OPTIONAL_PARENTHESES = 50
-
-
-VERSION_TO_FEATURES: Dict[TargetVersion, Set[Feature]] = {
- TargetVersion.PY27: {Feature.ASYNC_IDENTIFIERS},
- TargetVersion.PY33: {Feature.UNICODE_LITERALS, Feature.ASYNC_IDENTIFIERS},
- TargetVersion.PY34: {Feature.UNICODE_LITERALS, Feature.ASYNC_IDENTIFIERS},
- TargetVersion.PY35: {
- Feature.UNICODE_LITERALS,
- Feature.TRAILING_COMMA_IN_CALL,
- Feature.ASYNC_IDENTIFIERS,
- },
- TargetVersion.PY36: {
- Feature.UNICODE_LITERALS,
- Feature.F_STRINGS,
- Feature.NUMERIC_UNDERSCORES,
- Feature.TRAILING_COMMA_IN_CALL,
- Feature.TRAILING_COMMA_IN_DEF,
- Feature.ASYNC_IDENTIFIERS,
- },
- TargetVersion.PY37: {
- Feature.UNICODE_LITERALS,
- Feature.F_STRINGS,
- Feature.NUMERIC_UNDERSCORES,
- Feature.TRAILING_COMMA_IN_CALL,
- Feature.TRAILING_COMMA_IN_DEF,
- Feature.ASYNC_KEYWORDS,
- },
- TargetVersion.PY38: {
- Feature.UNICODE_LITERALS,
- Feature.F_STRINGS,
- Feature.NUMERIC_UNDERSCORES,
- Feature.TRAILING_COMMA_IN_CALL,
- Feature.TRAILING_COMMA_IN_DEF,
- Feature.ASYNC_KEYWORDS,
- Feature.ASSIGNMENT_EXPRESSIONS,
- Feature.POS_ONLY_ARGUMENTS,
- },
- TargetVersion.PY39: {
- Feature.UNICODE_LITERALS,
- Feature.F_STRINGS,
- Feature.NUMERIC_UNDERSCORES,
- Feature.TRAILING_COMMA_IN_CALL,
- Feature.TRAILING_COMMA_IN_DEF,
- Feature.ASYNC_KEYWORDS,
- Feature.ASSIGNMENT_EXPRESSIONS,
- Feature.RELAXED_DECORATORS,
- Feature.POS_ONLY_ARGUMENTS,
- },
-}
-
-
-@dataclass
-class Mode:
- target_versions: Set[TargetVersion] = field(default_factory=set)
- line_length: int = DEFAULT_LINE_LENGTH
- string_normalization: bool = True
- is_pyi: bool = False
- magic_trailing_comma: bool = True
- experimental_string_processing: bool = False
-
- def get_cache_key(self) -> str:
- if self.target_versions:
- version_str = ",".join(
- str(version.value)
- for version in sorted(self.target_versions, key=lambda v: v.value)
- )
- else:
- version_str = "-"
- parts = [
- version_str,
- str(self.line_length),
- str(int(self.string_normalization)),
- str(int(self.is_pyi)),
- str(int(self.magic_trailing_comma)),
- str(int(self.experimental_string_processing)),
- ]
- return ".".join(parts)
-
-
# Legacy name, left for integrations.
FileMode = Mode
-def supports_feature(target_versions: Set[TargetVersion], feature: Feature) -> bool:
- return all(feature in VERSION_TO_FEATURES[version] for version in target_versions)
-
-
-def find_pyproject_toml(path_search_start: Tuple[str, ...]) -> Optional[str]:
- """Find the absolute filepath to a pyproject.toml if it exists"""
- path_project_root = find_project_root(path_search_start)
- path_pyproject_toml = path_project_root / "pyproject.toml"
- if path_pyproject_toml.is_file():
- return str(path_pyproject_toml)
-
- try:
- path_user_pyproject_toml = find_user_pyproject_toml()
- return (
- str(path_user_pyproject_toml)
- if path_user_pyproject_toml.is_file()
- else None
- )
- except PermissionError as e:
- # We do not have access to the user-level config directory, so ignore it.
- err(f"Ignoring user configuration directory due to {e!r}")
- return None
-
-
-def parse_pyproject_toml(path_config: str) -> Dict[str, Any]:
- """Parse a pyproject toml file, pulling out relevant parts for Black
-
- If parsing fails, will raise a toml.TomlDecodeError
- """
- pyproject_toml = toml.load(path_config)
- config = pyproject_toml.get("tool", {}).get("black", {})
- return {k.replace("--", "").replace("-", "_"): v for k, v in config.items()}
-
-
def read_pyproject_toml(
ctx: click.Context, param: click.Parameter, value: Optional[str]
) -> Optional[str]:
@@ -349,7 +104,7 @@ def read_pyproject_toml(
try:
config = parse_pyproject_toml(value)
- except (toml.TomlDecodeError, OSError) as e:
+ except (OSError, ValueError) as e:
raise click.FileError(
filename=value, hint=f"Error reading configuration file: {e}"
)
@@ -391,6 +146,17 @@ def target_version_option_callback(
return [TargetVersion[val.upper()] for val in v]
+def re_compile_maybe_verbose(regex: str) -> Pattern[str]:
+ """Compile a regular expression string in `regex`.
+
+ If it contains newlines, use verbose mode.
+ """
+ if "\n" in regex:
+ regex = "(?x)" + regex
+ compiled: Pattern[str] = re.compile(regex)
+ return compiled
+
+
def validate_regex(
ctx: click.Context,
param: click.Parameter,
@@ -945,42 +711,6 @@ def format_file_in_place(
return True
-def color_diff(contents: str) -> str:
- """Inject the ANSI color codes to the diff."""
- lines = contents.split("\n")
- for i, line in enumerate(lines):
- if line.startswith("+++") or line.startswith("---"):
- line = "\033[1;37m" + line + "\033[0m" # bold white, reset
- elif line.startswith("@@"):
- line = "\033[36m" + line + "\033[0m" # cyan, reset
- elif line.startswith("+"):
- line = "\033[32m" + line + "\033[0m" # green, reset
- elif line.startswith("-"):
- line = "\033[31m" + line + "\033[0m" # red, reset
- lines[i] = line
- return "\n".join(lines)
-
-
-def wrap_stream_for_windows(
- f: io.TextIOWrapper,
-) -> Union[io.TextIOWrapper, "colorama.AnsiToWin32"]:
- """
- Wrap stream with colorama's wrap_stream so colors are shown on Windows.
-
- If `colorama` is unavailable, the original stream is returned unmodified.
- Otherwise, the `wrap_stream()` function determines whether the stream needs
- to be wrapped for a Windows environment and will accordingly either return
- an `AnsiToWin32` wrapper or the original stream.
- """
- try:
- from colorama.initialise import wrap_stream
- except ImportError:
- return f
- else:
- # Set `strip=False` to avoid needing to modify test_express_diff_with_color.
- return wrap_stream(f, convert=None, strip=False, autoreset=False, wrap=True)
-
-
def format_stdin_to_stdout(
fast: bool, *, write_back: WriteBack = WriteBack.NO, mode: Mode
) -> bool:
@@ -1127,5896 +857,197 @@ def decode_bytes(src: bytes) -> Tuple[FileContent, Encoding, NewLine]:
return tiow.read(), encoding, newline
-def get_grammars(target_versions: Set[TargetVersion]) -> List[Grammar]:
- if not target_versions:
- # No target_version specified, so try all grammars.
- return [
- # Python 3.7+
- pygram.python_grammar_no_print_statement_no_exec_statement_async_keywords,
- # Python 3.0-3.6
- pygram.python_grammar_no_print_statement_no_exec_statement,
- # Python 2.7 with future print_function import
- pygram.python_grammar_no_print_statement,
- # Python 2.7
- pygram.python_grammar,
- ]
-
- if all(version.is_python2() for version in target_versions):
- # Python 2-only code, so try Python 2 grammars.
- return [
- # Python 2.7 with future print_function import
- pygram.python_grammar_no_print_statement,
- # Python 2.7
- pygram.python_grammar,
- ]
-
- # Python 3-compatible code, so only try Python 3 grammar.
- grammars = []
- # If we have to parse both, try to parse async as a keyword first
- if not supports_feature(target_versions, Feature.ASYNC_IDENTIFIERS):
- # Python 3.7+
- grammars.append(
- pygram.python_grammar_no_print_statement_no_exec_statement_async_keywords
- )
- if not supports_feature(target_versions, Feature.ASYNC_KEYWORDS):
- # Python 3.0-3.6
- grammars.append(pygram.python_grammar_no_print_statement_no_exec_statement)
- # At least one of the above branches must have been taken, because every Python
- # version has exactly one of the two 'ASYNC_*' flags
- return grammars
-
-
-def lib2to3_parse(src_txt: str, target_versions: Iterable[TargetVersion] = ()) -> Node:
- """Given a string with source, return the lib2to3 Node."""
- if not src_txt.endswith("\n"):
- src_txt += "\n"
-
- for grammar in get_grammars(set(target_versions)):
- drv = driver.Driver(grammar, pytree.convert)
- try:
- result = drv.parse_string(src_txt, True)
- break
-
- except ParseError as pe:
- lineno, column = pe.context[1]
- lines = src_txt.splitlines()
- try:
- faulty_line = lines[lineno - 1]
- except IndexError:
- faulty_line = "<line number missing in source>"
- exc = InvalidInput(f"Cannot parse: {lineno}:{column}: {faulty_line}")
- else:
- raise exc from None
-
- if isinstance(result, Leaf):
- result = Node(syms.file_input, [result])
- return result
-
-
-def lib2to3_unparse(node: Node) -> str:
- """Given a lib2to3 node, return its string representation."""
- code = str(node)
- return code
-
-
-class Visitor(Generic[T]):
- """Basic lib2to3 visitor that yields things of type `T` on `visit()`."""
+def get_features_used(node: Node) -> Set[Feature]:
+ """Return a set of (relatively) new Python features used in this file.
- def visit(self, node: LN) -> Iterator[T]:
- """Main method to visit `node` and its children.
+ Currently looking for:
+ - f-strings;
+ - underscores in numeric literals;
+ - trailing commas after * or ** in function signatures and calls;
+ - positional only arguments in function signatures and lambdas;
+ - assignment expression;
+ - relaxed decorator syntax;
+ """
+ features: Set[Feature] = set()
+ for n in node.pre_order():
+ if n.type == token.STRING:
+ value_head = n.value[:2] # type: ignore
+ if value_head in {'f"', 'F"', "f'", "F'", "rf", "fr", "RF", "FR"}:
+ features.add(Feature.F_STRINGS)
- It tries to find a `visit_*()` method for the given `node.type`, like
- `visit_simple_stmt` for Node objects or `visit_INDENT` for Leaf objects.
- If no dedicated `visit_*()` method is found, chooses `visit_default()`
- instead.
+ elif n.type == token.NUMBER:
+ if "_" in n.value: # type: ignore
+ features.add(Feature.NUMERIC_UNDERSCORES)
- Then yields objects of type `T` from the selected visitor.
- """
- if node.type < 256:
- name = token.tok_name[node.type]
- else:
- name = str(type_repr(node.type))
- # We explicitly branch on whether a visitor exists (instead of
- # using self.visit_default as the default arg to getattr) in order
- # to save needing to create a bound method object and so mypyc can
- # generate a native call to visit_default.
- visitf = getattr(self, f"visit_{name}", None)
- if visitf:
- yield from visitf(node)
- else:
- yield from self.visit_default(node)
-
- def visit_default(self, node: LN) -> Iterator[T]:
- """Default `visit_*()` implementation. Recurses to children of `node`."""
- if isinstance(node, Node):
- for child in node.children:
- yield from self.visit(child)
-
-
-@dataclass
-class DebugVisitor(Visitor[T]):
- tree_depth: int = 0
-
- def visit_default(self, node: LN) -> Iterator[T]:
- indent = " " * (2 * self.tree_depth)
- if isinstance(node, Node):
- _type = type_repr(node.type)
- out(f"{indent}{_type}", fg="yellow")
- self.tree_depth += 1
- for child in node.children:
- yield from self.visit(child)
-
- self.tree_depth -= 1
- out(f"{indent}/{_type}", fg="yellow", bold=False)
- else:
- _type = token.tok_name.get(node.type, str(node.type))
- out(f"{indent}{_type}", fg="blue", nl=False)
- if node.prefix:
- # We don't have to handle prefixes for `Node` objects since
- # that delegates to the first child anyway.
- out(f" {node.prefix!r}", fg="green", bold=False, nl=False)
- out(f" {node.value!r}", fg="blue", bold=False)
+ elif n.type == token.SLASH:
+ if n.parent and n.parent.type in {syms.typedargslist, syms.arglist}:
+ features.add(Feature.POS_ONLY_ARGUMENTS)
- @classmethod
- def show(cls, code: Union[str, Leaf, Node]) -> None:
- """Pretty-print the lib2to3 AST of a given string of `code`.
-
- Convenience method for debugging.
- """
- v: DebugVisitor[None] = DebugVisitor()
- if isinstance(code, str):
- code = lib2to3_parse(code)
- list(v.visit(code))
-
-
-WHITESPACE: Final = {token.DEDENT, token.INDENT, token.NEWLINE}
-STATEMENT: Final = {
- syms.if_stmt,
- syms.while_stmt,
- syms.for_stmt,
- syms.try_stmt,
- syms.except_clause,
- syms.with_stmt,
- syms.funcdef,
- syms.classdef,
-}
-STANDALONE_COMMENT: Final = 153
-token.tok_name[STANDALONE_COMMENT] = "STANDALONE_COMMENT"
-LOGIC_OPERATORS: Final = {"and", "or"}
-COMPARATORS: Final = {
- token.LESS,
- token.GREATER,
- token.EQEQUAL,
- token.NOTEQUAL,
- token.LESSEQUAL,
- token.GREATEREQUAL,
-}
-MATH_OPERATORS: Final = {
- token.VBAR,
- token.CIRCUMFLEX,
- token.AMPER,
- token.LEFTSHIFT,
- token.RIGHTSHIFT,
- token.PLUS,
- token.MINUS,
- token.STAR,
- token.SLASH,
- token.DOUBLESLASH,
- token.PERCENT,
- token.AT,
- token.TILDE,
- token.DOUBLESTAR,
-}
-STARS: Final = {token.STAR, token.DOUBLESTAR}
-VARARGS_SPECIALS: Final = STARS | {token.SLASH}
-VARARGS_PARENTS: Final = {
- syms.arglist,
- syms.argument, # double star in arglist
- syms.trailer, # single argument to call
- syms.typedargslist,
- syms.varargslist, # lambdas
-}
-UNPACKING_PARENTS: Final = {
- syms.atom, # single element of a list or set literal
- syms.dictsetmaker,
- syms.listmaker,
- syms.testlist_gexp,
- syms.testlist_star_expr,
-}
-TEST_DESCENDANTS: Final = {
- syms.test,
- syms.lambdef,
- syms.or_test,
- syms.and_test,
- syms.not_test,
- syms.comparison,
- syms.star_expr,
- syms.expr,
- syms.xor_expr,
- syms.and_expr,
- syms.shift_expr,
- syms.arith_expr,
- syms.trailer,
- syms.term,
- syms.power,
-}
-ASSIGNMENTS: Final = {
- "=",
- "+=",
- "-=",
- "*=",
- "@=",
- "/=",
- "%=",
- "&=",
- "|=",
- "^=",
- "<<=",
- ">>=",
- "**=",
- "//=",
-}
-COMPREHENSION_PRIORITY: Final = 20
-COMMA_PRIORITY: Final = 18
-TERNARY_PRIORITY: Final = 16
-LOGIC_PRIORITY: Final = 14
-STRING_PRIORITY: Final = 12
-COMPARATOR_PRIORITY: Final = 10
-MATH_PRIORITIES: Final = {
- token.VBAR: 9,
- token.CIRCUMFLEX: 8,
- token.AMPER: 7,
- token.LEFTSHIFT: 6,
- token.RIGHTSHIFT: 6,
- token.PLUS: 5,
- token.MINUS: 5,
- token.STAR: 4,
- token.SLASH: 4,
- token.DOUBLESLASH: 4,
- token.PERCENT: 4,
- token.AT: 4,
- token.TILDE: 3,
- token.DOUBLESTAR: 2,
-}
-DOT_PRIORITY: Final = 1
-
-
-@dataclass
-class BracketTracker:
- """Keeps track of brackets on a line."""
-
- depth: int = 0
- bracket_match: Dict[Tuple[Depth, NodeType], Leaf] = field(default_factory=dict)
- delimiters: Dict[LeafID, Priority] = field(default_factory=dict)
- previous: Optional[Leaf] = None
- _for_loop_depths: List[int] = field(default_factory=list)
- _lambda_argument_depths: List[int] = field(default_factory=list)
- invisible: List[Leaf] = field(default_factory=list)
-
- def mark(self, leaf: Leaf) -> None:
- """Mark `leaf` with bracket-related metadata. Keep track of delimiters.
-
- All leaves receive an int `bracket_depth` field that stores how deep
- within brackets a given leaf is. 0 means there are no enclosing brackets
- that started on this line.
-
- If a leaf is itself a closing bracket, it receives an `opening_bracket`
- field that it forms a pair with. This is a one-directional link to
- avoid reference cycles.
-
- If a leaf is a delimiter (a token on which Black can split the line if
- needed) and it's on depth 0, its `id()` is stored in the tracker's
- `delimiters` field.
- """
- if leaf.type == token.COMMENT:
- return
-
- self.maybe_decrement_after_for_loop_variable(leaf)
- self.maybe_decrement_after_lambda_arguments(leaf)
- if leaf.type in CLOSING_BRACKETS:
- self.depth -= 1
- try:
- opening_bracket = self.bracket_match.pop((self.depth, leaf.type))
- except KeyError as e:
- raise BracketMatchError(
- "Unable to match a closing bracket to the following opening"
- f" bracket: {leaf}"
- ) from e
- leaf.opening_bracket = opening_bracket
- if not leaf.value:
- self.invisible.append(leaf)
- leaf.bracket_depth = self.depth
- if self.depth == 0:
- delim = is_split_before_delimiter(leaf, self.previous)
- if delim and self.previous is not None:
- self.delimiters[id(self.previous)] = delim
- else:
- delim = is_split_after_delimiter(leaf, self.previous)
- if delim:
- self.delimiters[id(leaf)] = delim
- if leaf.type in OPENING_BRACKETS:
- self.bracket_match[self.depth, BRACKET[leaf.type]] = leaf
- self.depth += 1
- if not leaf.value:
- self.invisible.append(leaf)
- self.previous = leaf
- self.maybe_increment_lambda_arguments(leaf)
- self.maybe_increment_for_loop_variable(leaf)
-
- def any_open_brackets(self) -> bool:
- """Return True if there is an yet unmatched open bracket on the line."""
- return bool(self.bracket_match)
-
- def max_delimiter_priority(self, exclude: Iterable[LeafID] = ()) -> Priority:
- """Return the highest priority of a delimiter found on the line.
-
- Values are consistent with what `is_split_*_delimiter()` return.
- Raises ValueError on no delimiters.
- """
- return max(v for k, v in self.delimiters.items() if k not in exclude)
-
- def delimiter_count_with_priority(self, priority: Priority = 0) -> int:
- """Return the number of delimiters with the given `priority`.
-
- If no `priority` is passed, defaults to max priority on the line.
- """
- if not self.delimiters:
- return 0
-
- priority = priority or self.max_delimiter_priority()
- return sum(1 for p in self.delimiters.values() if p == priority)
-
- def maybe_increment_for_loop_variable(self, leaf: Leaf) -> bool:
- """In a for loop, or comprehension, the variables are often unpacks.
-
- To avoid splitting on the comma in this situation, increase the depth of
- tokens between `for` and `in`.
- """
- if leaf.type == token.NAME and leaf.value == "for":
- self.depth += 1
- self._for_loop_depths.append(self.depth)
- return True
+ elif n.type == token.COLONEQUAL:
+ features.add(Feature.ASSIGNMENT_EXPRESSIONS)
- return False
+ elif n.type == syms.decorator:
+ if len(n.children) > 1 and not is_simple_decorator_expression(
+ n.children[1]
+ ):
+ features.add(Feature.RELAXED_DECORATORS)
- def maybe_decrement_after_for_loop_variable(self, leaf: Leaf) -> bool:
- """See `maybe_increment_for_loop_variable` above for explanation."""
- if (
- self._for_loop_depths
- and self._for_loop_depths[-1] == self.depth
- and leaf.type == token.NAME
- and leaf.value == "in"
+ elif (
+ n.type in {syms.typedargslist, syms.arglist}
+ and n.children
+ and n.children[-1].type == token.COMMA
):
- self.depth -= 1
- self._for_loop_depths.pop()
- return True
-
- return False
+ if n.type == syms.typedargslist:
+ feature = Feature.TRAILING_COMMA_IN_DEF
+ else:
+ feature = Feature.TRAILING_COMMA_IN_CALL
- def maybe_increment_lambda_arguments(self, leaf: Leaf) -> bool:
- """In a lambda expression, there might be more than one argument.
+ for ch in n.children:
+ if ch.type in STARS:
+ features.add(feature)
- To avoid splitting on the comma in this situation, increase the depth of
- tokens between `lambda` and `:`.
- """
- if leaf.type == token.NAME and leaf.value == "lambda":
- self.depth += 1
- self._lambda_argument_depths.append(self.depth)
- return True
+ if ch.type == syms.argument:
+ for argch in ch.children:
+ if argch.type in STARS:
+ features.add(feature)
- return False
+ return features
- def maybe_decrement_after_lambda_arguments(self, leaf: Leaf) -> bool:
- """See `maybe_increment_lambda_arguments` above for explanation."""
- if (
- self._lambda_argument_depths
- and self._lambda_argument_depths[-1] == self.depth
- and leaf.type == token.COLON
- ):
- self.depth -= 1
- self._lambda_argument_depths.pop()
- return True
- return False
+def detect_target_versions(node: Node) -> Set[TargetVersion]:
+ """Detect the version to target based on the nodes used."""
+ features = get_features_used(node)
+ return {
+ version for version in TargetVersion if features <= VERSION_TO_FEATURES[version]
+ }
- def get_open_lsqb(self) -> Optional[Leaf]:
- """Return the most recent opening square bracket (if any)."""
- return self.bracket_match.get((self.depth - 1, token.RSQB))
-
-
-@dataclass
-class Line:
- """Holds leaves and comments. Can be printed with `str(line)`."""
-
- mode: Mode
- depth: int = 0
- leaves: List[Leaf] = field(default_factory=list)
- # keys ordered like `leaves`
- comments: Dict[LeafID, List[Leaf]] = field(default_factory=dict)
- bracket_tracker: BracketTracker = field(default_factory=BracketTracker)
- inside_brackets: bool = False
- should_split_rhs: bool = False
- magic_trailing_comma: Optional[Leaf] = None
-
- def append(self, leaf: Leaf, preformatted: bool = False) -> None:
- """Add a new `leaf` to the end of the line.
-
- Unless `preformatted` is True, the `leaf` will receive a new consistent
- whitespace prefix and metadata applied by :class:`BracketTracker`.
- Trailing commas are maybe removed, unpacked for loop variables are
- demoted from being delimiters.
-
- Inline comments are put aside.
- """
- has_value = leaf.type in BRACKETS or bool(leaf.value.strip())
- if not has_value:
- return
-
- if token.COLON == leaf.type and self.is_class_paren_empty:
- del self.leaves[-2:]
- if self.leaves and not preformatted:
- # Note: at this point leaf.prefix should be empty except for
- # imports, for which we only preserve newlines.
- leaf.prefix += whitespace(
- leaf, complex_subscript=self.is_complex_subscript(leaf)
- )
- if self.inside_brackets or not preformatted:
- self.bracket_tracker.mark(leaf)
- if self.mode.magic_trailing_comma:
- if self.has_magic_trailing_comma(leaf):
- self.magic_trailing_comma = leaf
- elif self.has_magic_trailing_comma(leaf, ensure_removable=True):
- self.remove_trailing_comma()
- if not self.append_comment(leaf):
- self.leaves.append(leaf)
-
- def append_safe(self, leaf: Leaf, preformatted: bool = False) -> None:
- """Like :func:`append()` but disallow invalid standalone comment structure.
-
- Raises ValueError when any `leaf` is appended after a standalone comment
- or when a standalone comment is not the first leaf on the line.
- """
- if self.bracket_tracker.depth == 0:
- if self.is_comment:
- raise ValueError("cannot append to standalone comments")
-
- if self.leaves and leaf.type == STANDALONE_COMMENT:
- raise ValueError(
- "cannot append standalone comments to a populated line"
- )
- self.append(leaf, preformatted=preformatted)
-
- @property
- def is_comment(self) -> bool:
- """Is this line a standalone comment?"""
- return len(self.leaves) == 1 and self.leaves[0].type == STANDALONE_COMMENT
-
- @property
- def is_decorator(self) -> bool:
- """Is this line a decorator?"""
- return bool(self) and self.leaves[0].type == token.AT
-
- @property
- def is_import(self) -> bool:
- """Is this an import line?"""
- return bool(self) and is_import(self.leaves[0])
-
- @property
- def is_class(self) -> bool:
- """Is this line a class definition?"""
- return (
- bool(self)
- and self.leaves[0].type == token.NAME
- and self.leaves[0].value == "class"
- )
+def get_future_imports(node: Node) -> Set[str]:
+ """Return a set of __future__ imports in the file."""
+ imports: Set[str] = set()
- @property
- def is_stub_class(self) -> bool:
- """Is this line a class definition with a body consisting only of "..."?"""
- return self.is_class and self.leaves[-3:] == [
- Leaf(token.DOT, ".") for _ in range(3)
- ]
-
- @property
- def is_def(self) -> bool:
- """Is this a function definition? (Also returns True for async defs.)"""
- try:
- first_leaf = self.leaves[0]
- except IndexError:
- return False
-
- try:
- second_leaf: Optional[Leaf] = self.leaves[1]
- except IndexError:
- second_leaf = None
- return (first_leaf.type == token.NAME and first_leaf.value == "def") or (
- first_leaf.type == token.ASYNC
- and second_leaf is not None
- and second_leaf.type == token.NAME
- and second_leaf.value == "def"
- )
+ def get_imports_from_children(children: List[LN]) -> Generator[str, None, None]:
+ for child in children:
+ if isinstance(child, Leaf):
+ if child.type == token.NAME:
+ yield child.value
- @property
- def is_class_paren_empty(self) -> bool:
- """Is this a class with no base classes but using parentheses?
-
- Those are unnecessary and should be removed.
- """
- return (
- bool(self)
- and len(self.leaves) == 4
- and self.is_class
- and self.leaves[2].type == token.LPAR
- and self.leaves[2].value == "("
- and self.leaves[3].type == token.RPAR
- and self.leaves[3].value == ")"
- )
+ elif child.type == syms.import_as_name:
+ orig_name = child.children[0]
+ assert isinstance(orig_name, Leaf), "Invalid syntax parsing imports"
+ assert orig_name.type == token.NAME, "Invalid syntax parsing imports"
+ yield orig_name.value
- @property
- def is_triple_quoted_string(self) -> bool:
- """Is the line a triple quoted string?"""
- return (
- bool(self)
- and self.leaves[0].type == token.STRING
- and self.leaves[0].value.startswith(('"""', "'''"))
- )
+ elif child.type == syms.import_as_names:
+ yield from get_imports_from_children(child.children)
- def contains_standalone_comments(self, depth_limit: int = sys.maxsize) -> bool:
- """If so, needs to be split before emitting."""
- for leaf in self.leaves:
- if leaf.type == STANDALONE_COMMENT and leaf.bracket_depth <= depth_limit:
- return True
+ else:
+ raise AssertionError("Invalid syntax parsing imports")
- return False
+ for child in node.children:
+ if child.type != syms.simple_stmt:
+ break
- def contains_uncollapsable_type_comments(self) -> bool:
- ignored_ids = set()
- try:
- last_leaf = self.leaves[-1]
- ignored_ids.add(id(last_leaf))
- if last_leaf.type == token.COMMA or (
- last_leaf.type == token.RPAR and not last_leaf.value
+ first_child = child.children[0]
+ if isinstance(first_child, Leaf):
+ # Continue looking if we see a docstring; otherwise stop.
+ if (
+ len(child.children) == 2
+ and first_child.type == token.STRING
+ and child.children[1].type == token.NEWLINE
):
- # When trailing commas or optional parens are inserted by Black for
- # consistency, comments after the previous last element are not moved
- # (they don't have to, rendering will still be correct). So we ignore
- # trailing commas and invisible.
- last_leaf = self.leaves[-2]
- ignored_ids.add(id(last_leaf))
- except IndexError:
- return False
-
- # A type comment is uncollapsable if it is attached to a leaf
- # that isn't at the end of the line (since that could cause it
- # to get associated to a different argument) or if there are
- # comments before it (since that could cause it to get hidden
- # behind a comment.
- comment_seen = False
- for leaf_id, comments in self.comments.items():
- for comment in comments:
- if is_type_comment(comment):
- if comment_seen or (
- not is_type_comment(comment, " ignore")
- and leaf_id not in ignored_ids
- ):
- return True
-
- comment_seen = True
-
- return False
-
- def contains_unsplittable_type_ignore(self) -> bool:
- if not self.leaves:
- return False
-
- # If a 'type: ignore' is attached to the end of a line, we
- # can't split the line, because we can't know which of the
- # subexpressions the ignore was meant to apply to.
- #
- # We only want this to apply to actual physical lines from the
- # original source, though: we don't want the presence of a
- # 'type: ignore' at the end of a multiline expression to
- # justify pushing it all onto one line. Thus we
- # (unfortunately) need to check the actual source lines and
- # only report an unsplittable 'type: ignore' if this line was
- # one line in the original code.
-
- # Grab the first and last line numbers, skipping generated leaves
- first_line = next((leaf.lineno for leaf in self.leaves if leaf.lineno != 0), 0)
- last_line = next(
- (leaf.lineno for leaf in reversed(self.leaves) if leaf.lineno != 0), 0
- )
-
- if first_line == last_line:
- # We look at the last two leaves since a comma or an
- # invisible paren could have been added at the end of the
- # line.
- for node in self.leaves[-2:]:
- for comment in self.comments.get(id(node), []):
- if is_type_comment(comment, " ignore"):
- return True
-
- return False
-
- def contains_multiline_strings(self) -> bool:
- return any(is_multiline_string(leaf) for leaf in self.leaves)
-
- def has_magic_trailing_comma(
- self, closing: Leaf, ensure_removable: bool = False
- ) -> bool:
- """Return True if we have a magic trailing comma, that is when:
- - there's a trailing comma here
- - it's not a one-tuple
- Additionally, if ensure_removable:
- - it's not from square bracket indexing
- """
- if not (
- closing.type in CLOSING_BRACKETS
- and self.leaves
- and self.leaves[-1].type == token.COMMA
- ):
- return False
-
- if closing.type == token.RBRACE:
- return True
-
- if closing.type == token.RSQB:
- if not ensure_removable:
- return True
- comma = self.leaves[-1]
- return bool(comma.parent and comma.parent.type == syms.listmaker)
+ continue
- if self.is_import:
- return True
+ break
- if not is_one_tuple_between(closing.opening_bracket, closing, self.leaves):
- return True
+ elif first_child.type == syms.import_from:
+ module_name = first_child.children[1]
+ if not isinstance(module_name, Leaf) or module_name.value != "__future__":
+ break
- return False
+ imports |= set(get_imports_from_children(first_child.children[3:]))
+ else:
+ break
- def append_comment(self, comment: Leaf) -> bool:
- """Add an inline or standalone comment to the line."""
- if (
- comment.type == STANDALONE_COMMENT
- and self.bracket_tracker.any_open_brackets()
- ):
- comment.prefix = ""
- return False
-
- if comment.type != token.COMMENT:
- return False
-
- if not self.leaves:
- comment.type = STANDALONE_COMMENT
- comment.prefix = ""
- return False
-
- last_leaf = self.leaves[-1]
- if (
- last_leaf.type == token.RPAR
- and not last_leaf.value
- and last_leaf.parent
- and len(list(last_leaf.parent.leaves())) <= 3
- and not is_type_comment(comment)
- ):
- # Comments on an optional parens wrapping a single leaf should belong to
- # the wrapped node except if it's a type comment. Pinning the comment like
- # this avoids unstable formatting caused by comment migration.
- if len(self.leaves) < 2:
- comment.type = STANDALONE_COMMENT
- comment.prefix = ""
- return False
-
- last_leaf = self.leaves[-2]
- self.comments.setdefault(id(last_leaf), []).append(comment)
- return True
+ return imports
- def comments_after(self, leaf: Leaf) -> List[Leaf]:
- """Generate comments that should appear directly after `leaf`."""
- return self.comments.get(id(leaf), [])
- def remove_trailing_comma(self) -> None:
- """Remove the trailing comma and moves the comments attached to it."""
- trailing_comma = self.leaves.pop()
- trailing_comma_comments = self.comments.pop(id(trailing_comma), [])
- self.comments.setdefault(id(self.leaves[-1]), []).extend(
- trailing_comma_comments
+def assert_equivalent(src: str, dst: str, *, pass_num: int = 1) -> None:
+ """Raise AssertionError if `src` and `dst` aren't equivalent."""
+ try:
+ src_ast = parse_ast(src)
+ except Exception as exc:
+ raise AssertionError(
+ "cannot use --safe with this file; failed to parse source file. AST"
+ f" error message: {exc}"
)
- def is_complex_subscript(self, leaf: Leaf) -> bool:
- """Return True iff `leaf` is part of a slice with non-trivial exprs."""
- open_lsqb = self.bracket_tracker.get_open_lsqb()
- if open_lsqb is None:
- return False
-
- subscript_start = open_lsqb.next_sibling
+ try:
+ dst_ast = parse_ast(dst)
+ except Exception as exc:
+ log = dump_to_file("".join(traceback.format_tb(exc.__traceback__)), dst)
+ raise AssertionError(
+ f"INTERNAL ERROR: Black produced invalid code on pass {pass_num}: {exc}. "
+ "Please report a bug on https://github.com/psf/black/issues. "
+ f"This invalid output might be helpful: {log}"
+ ) from None
- if isinstance(subscript_start, Node):
- if subscript_start.type == syms.listmaker:
- return False
+ src_ast_str = "\n".join(stringify_ast(src_ast))
+ dst_ast_str = "\n".join(stringify_ast(dst_ast))
+ if src_ast_str != dst_ast_str:
+ log = dump_to_file(diff(src_ast_str, dst_ast_str, "src", "dst"))
+ raise AssertionError(
+ "INTERNAL ERROR: Black produced code that is not equivalent to the"
+ f" source on pass {pass_num}. Please report a bug on "
+ f"https://github.com/psf/black/issues. This diff might be helpful: {log}"
+ ) from None
- if subscript_start.type == syms.subscriptlist:
- subscript_start = child_towards(subscript_start, leaf)
- return subscript_start is not None and any(
- n.type in TEST_DESCENDANTS for n in subscript_start.pre_order()
- )
- def clone(self) -> "Line":
- return Line(
- mode=self.mode,
- depth=self.depth,
- inside_brackets=self.inside_brackets,
- should_split_rhs=self.should_split_rhs,
- magic_trailing_comma=self.magic_trailing_comma,
+def assert_stable(src: str, dst: str, mode: Mode) -> None:
+ """Raise AssertionError if `dst` reformats differently the second time."""
+ newdst = format_str(dst, mode=mode)
+ if dst != newdst:
+ log = dump_to_file(
+ str(mode),
+ diff(src, dst, "source", "first pass"),
+ diff(dst, newdst, "first pass", "second pass"),
)
+ raise AssertionError(
+ "INTERNAL ERROR: Black produced different code on the second pass of the"
+ " formatter. Please report a bug on https://github.com/psf/black/issues."
+ f" This diff might be helpful: {log}"
+ ) from None
- def __str__(self) -> str:
- """Render the line."""
- if not self:
- return "\n"
- indent = " " * self.depth
- leaves = iter(self.leaves)
- first = next(leaves)
- res = f"{first.prefix}{indent}{first.value}"
- for leaf in leaves:
- res += str(leaf)
- for comment in itertools.chain.from_iterable(self.comments.values()):
- res += str(comment)
+@contextmanager
+def nullcontext() -> Iterator[None]:
+ """Return an empty context manager.
- return res + "\n"
+ To be used like `nullcontext` in Python 3.7.
+ """
+ yield
- def __bool__(self) -> bool:
- """Return True if the line has leaves or comments."""
- return bool(self.leaves or self.comments)
+def patch_click() -> None:
+ """Make Click not crash.
-@dataclass
-class EmptyLineTracker:
- """Provides a stateful method that returns the number of potential extra
- empty lines needed before and after the currently processed line.
+ On certain misconfigured environments, Python 3 selects the ASCII encoding as the
+ default which restricts paths that it can access during the lifetime of the
+ application. Click refuses to work in this scenario by raising a RuntimeError.
- Note: this tracker works on lines that haven't been split yet. It assumes
- the prefix of the first leaf consists of optional newlines. Those newlines
- are consumed by `maybe_empty_lines()` and included in the computation.
+ In case of Black the likelihood that non-ASCII characters are going to be used in
+ file paths is minimal since it's Python source code. Moreover, this crash was
+ spurious on Python 3.7 thanks to PEP 538 and PEP 540.
"""
+ try:
+ from click import core
+ from click import _unicodefun # type: ignore
+ except ModuleNotFoundError:
+ return
- is_pyi: bool = False
- previous_line: Optional[Line] = None
- previous_after: int = 0
- previous_defs: List[int] = field(default_factory=list)
-
- def maybe_empty_lines(self, current_line: Line) -> Tuple[int, int]:
- """Return the number of extra empty lines before and after the `current_line`.
-
- This is for separating `def`, `async def` and `class` with extra empty
- lines (two on module-level).
- """
- before, after = self._maybe_empty_lines(current_line)
- before = (
- # Black should not insert empty lines at the beginning
- # of the file
- 0
- if self.previous_line is None
- else before - self.previous_after
- )
- self.previous_after = after
- self.previous_line = current_line
- return before, after
-
- def _maybe_empty_lines(self, current_line: Line) -> Tuple[int, int]:
- max_allowed = 1
- if current_line.depth == 0:
- max_allowed = 1 if self.is_pyi else 2
- if current_line.leaves:
- # Consume the first leaf's extra newlines.
- first_leaf = current_line.leaves[0]
- before = first_leaf.prefix.count("\n")
- before = min(before, max_allowed)
- first_leaf.prefix = ""
- else:
- before = 0
- depth = current_line.depth
- while self.previous_defs and self.previous_defs[-1] >= depth:
- self.previous_defs.pop()
- if self.is_pyi:
- before = 0 if depth else 1
- else:
- before = 1 if depth else 2
- if current_line.is_decorator or current_line.is_def or current_line.is_class:
- return self._maybe_empty_lines_for_class_or_def(current_line, before)
-
- if (
- self.previous_line
- and self.previous_line.is_import
- and not current_line.is_import
- and depth == self.previous_line.depth
- ):
- return (before or 1), 0
-
- if (
- self.previous_line
- and self.previous_line.is_class
- and current_line.is_triple_quoted_string
- ):
- return before, 1
-
- return before, 0
-
- def _maybe_empty_lines_for_class_or_def(
- self, current_line: Line, before: int
- ) -> Tuple[int, int]:
- if not current_line.is_decorator:
- self.previous_defs.append(current_line.depth)
- if self.previous_line is None:
- # Don't insert empty lines before the first line in the file.
- return 0, 0
-
- if self.previous_line.is_decorator:
- if self.is_pyi and current_line.is_stub_class:
- # Insert an empty line after a decorated stub class
- return 0, 1
-
- return 0, 0
-
- if self.previous_line.depth < current_line.depth and (
- self.previous_line.is_class or self.previous_line.is_def
- ):
- return 0, 0
-
- if (
- self.previous_line.is_comment
- and self.previous_line.depth == current_line.depth
- and before == 0
- ):
- return 0, 0
-
- if self.is_pyi:
- if self.previous_line.depth > current_line.depth:
- newlines = 1
- elif current_line.is_class or self.previous_line.is_class:
- if current_line.is_stub_class and self.previous_line.is_stub_class:
- # No blank line between classes with an empty body
- newlines = 0
- else:
- newlines = 1
- elif (
- current_line.is_def or current_line.is_decorator
- ) and not self.previous_line.is_def:
- # Blank line between a block of functions (maybe with preceding
- # decorators) and a block of non-functions
- newlines = 1
- else:
- newlines = 0
- else:
- newlines = 2
- if current_line.depth and newlines:
- newlines -= 1
- return newlines, 0
-
-
-@dataclass
-class LineGenerator(Visitor[Line]):
- """Generates reformatted Line objects. Empty lines are not emitted.
-
- Note: destroys the tree it's visiting by mutating prefixes of its leaves
- in ways that will no longer stringify to valid Python code on the tree.
- """
-
- mode: Mode
- remove_u_prefix: bool = False
- current_line: Line = field(init=False)
-
- def line(self, indent: int = 0) -> Iterator[Line]:
- """Generate a line.
-
- If the line is empty, only emit if it makes sense.
- If the line is too long, split it first and then generate.
-
- If any lines were generated, set up a new current_line.
- """
- if not self.current_line:
- self.current_line.depth += indent
- return # Line is empty, don't emit. Creating a new one unnecessary.
-
- complete_line = self.current_line
- self.current_line = Line(mode=self.mode, depth=complete_line.depth + indent)
- yield complete_line
-
- def visit_default(self, node: LN) -> Iterator[Line]:
- """Default `visit_*()` implementation. Recurses to children of `node`."""
- if isinstance(node, Leaf):
- any_open_brackets = self.current_line.bracket_tracker.any_open_brackets()
- for comment in generate_comments(node):
- if any_open_brackets:
- # any comment within brackets is subject to splitting
- self.current_line.append(comment)
- elif comment.type == token.COMMENT:
- # regular trailing comment
- self.current_line.append(comment)
- yield from self.line()
-
- else:
- # regular standalone comment
- yield from self.line()
-
- self.current_line.append(comment)
- yield from self.line()
-
- normalize_prefix(node, inside_brackets=any_open_brackets)
- if self.mode.string_normalization and node.type == token.STRING:
- normalize_string_prefix(node, remove_u_prefix=self.remove_u_prefix)
- normalize_string_quotes(node)
- if node.type == token.NUMBER:
- normalize_numeric_literal(node)
- if node.type not in WHITESPACE:
- self.current_line.append(node)
- yield from super().visit_default(node)
-
- def visit_INDENT(self, node: Leaf) -> Iterator[Line]:
- """Increase indentation level, maybe yield a line."""
- # In blib2to3 INDENT never holds comments.
- yield from self.line(+1)
- yield from self.visit_default(node)
-
- def visit_DEDENT(self, node: Leaf) -> Iterator[Line]:
- """Decrease indentation level, maybe yield a line."""
- # The current line might still wait for trailing comments. At DEDENT time
- # there won't be any (they would be prefixes on the preceding NEWLINE).
- # Emit the line then.
- yield from self.line()
-
- # While DEDENT has no value, its prefix may contain standalone comments
- # that belong to the current indentation level. Get 'em.
- yield from self.visit_default(node)
-
- # Finally, emit the dedent.
- yield from self.line(-1)
-
- def visit_stmt(
- self, node: Node, keywords: Set[str], parens: Set[str]
- ) -> Iterator[Line]:
- """Visit a statement.
-
- This implementation is shared for `if`, `while`, `for`, `try`, `except`,
- `def`, `with`, `class`, `assert` and assignments.
-
- The relevant Python language `keywords` for a given statement will be
- NAME leaves within it. This methods puts those on a separate line.
-
- `parens` holds a set of string leaf values immediately after which
- invisible parens should be put.
- """
- normalize_invisible_parens(node, parens_after=parens)
- for child in node.children:
- if child.type == token.NAME and child.value in keywords: # type: ignore
- yield from self.line()
-
- yield from self.visit(child)
-
- def visit_suite(self, node: Node) -> Iterator[Line]:
- """Visit a suite."""
- if self.mode.is_pyi and is_stub_suite(node):
- yield from self.visit(node.children[2])
- else:
- yield from self.visit_default(node)
-
- def visit_simple_stmt(self, node: Node) -> Iterator[Line]:
- """Visit a statement without nested statements."""
- if first_child_is_arith(node):
- wrap_in_parentheses(node, node.children[0], visible=False)
- is_suite_like = node.parent and node.parent.type in STATEMENT
- if is_suite_like:
- if self.mode.is_pyi and is_stub_body(node):
- yield from self.visit_default(node)
- else:
- yield from self.line(+1)
- yield from self.visit_default(node)
- yield from self.line(-1)
-
- else:
- if (
- not self.mode.is_pyi
- or not node.parent
- or not is_stub_suite(node.parent)
- ):
- yield from self.line()
- yield from self.visit_default(node)
-
- def visit_async_stmt(self, node: Node) -> Iterator[Line]:
- """Visit `async def`, `async for`, `async with`."""
- yield from self.line()
-
- children = iter(node.children)
- for child in children:
- yield from self.visit(child)
-
- if child.type == token.ASYNC:
- break
-
- internal_stmt = next(children)
- for child in internal_stmt.children:
- yield from self.visit(child)
-
- def visit_decorators(self, node: Node) -> Iterator[Line]:
- """Visit decorators."""
- for child in node.children:
- yield from self.line()
- yield from self.visit(child)
-
- def visit_SEMI(self, leaf: Leaf) -> Iterator[Line]:
- """Remove a semicolon and put the other statement on a separate line."""
- yield from self.line()
-
- def visit_ENDMARKER(self, leaf: Leaf) -> Iterator[Line]:
- """End of file. Process outstanding comments and end with a newline."""
- yield from self.visit_default(leaf)
- yield from self.line()
-
- def visit_STANDALONE_COMMENT(self, leaf: Leaf) -> Iterator[Line]:
- if not self.current_line.bracket_tracker.any_open_brackets():
- yield from self.line()
- yield from self.visit_default(leaf)
-
- def visit_factor(self, node: Node) -> Iterator[Line]:
- """Force parentheses between a unary op and a binary power:
-
- -2 ** 8 -> -(2 ** 8)
- """
- _operator, operand = node.children
- if (
- operand.type == syms.power
- and len(operand.children) == 3
- and operand.children[1].type == token.DOUBLESTAR
- ):
- lpar = Leaf(token.LPAR, "(")
- rpar = Leaf(token.RPAR, ")")
- index = operand.remove() or 0
- node.insert_child(index, Node(syms.atom, [lpar, operand, rpar]))
- yield from self.visit_default(node)
-
- def visit_STRING(self, leaf: Leaf) -> Iterator[Line]:
- if is_docstring(leaf) and "\\\n" not in leaf.value:
- # We're ignoring docstrings with backslash newline escapes because changing
- # indentation of those changes the AST representation of the code.
- prefix = get_string_prefix(leaf.value)
- docstring = leaf.value[len(prefix) :] # Remove the prefix
- quote_char = docstring[0]
- # A natural way to remove the outer quotes is to do:
- # docstring = docstring.strip(quote_char)
- # but that breaks on """""x""" (which is '""x').
- # So we actually need to remove the first character and the next two
- # characters but only if they are the same as the first.
- quote_len = 1 if docstring[1] != quote_char else 3
- docstring = docstring[quote_len:-quote_len]
-
- if is_multiline_string(leaf):
- indent = " " * 4 * self.current_line.depth
- docstring = fix_docstring(docstring, indent)
- else:
- docstring = docstring.strip()
-
- if docstring:
- # Add some padding if the docstring starts / ends with a quote mark.
- if docstring[0] == quote_char:
- docstring = " " + docstring
- if docstring[-1] == quote_char:
- docstring += " "
- if docstring[-1] == "\\":
- backslash_count = len(docstring) - len(docstring.rstrip("\\"))
- if backslash_count % 2:
- # Odd number of tailing backslashes, add some padding to
- # avoid escaping the closing string quote.
- docstring += " "
- else:
- # Add some padding if the docstring is empty.
- docstring = " "
-
- # We could enforce triple quotes at this point.
- quote = quote_char * quote_len
- leaf.value = prefix + quote + docstring + quote
-
- yield from self.visit_default(leaf)
-
- def __post_init__(self) -> None:
- """You are in a twisty little maze of passages."""
- self.current_line = Line(mode=self.mode)
-
- v = self.visit_stmt
- Ã: Set[str] = set()
- self.visit_assert_stmt = partial(v, keywords={"assert"}, parens={"assert", ","})
- self.visit_if_stmt = partial(
- v, keywords={"if", "else", "elif"}, parens={"if", "elif"}
- )
- self.visit_while_stmt = partial(v, keywords={"while", "else"}, parens={"while"})
- self.visit_for_stmt = partial(v, keywords={"for", "else"}, parens={"for", "in"})
- self.visit_try_stmt = partial(
- v, keywords={"try", "except", "else", "finally"}, parens=Ã
- )
- self.visit_except_clause = partial(v, keywords={"except"}, parens=Ã)
- self.visit_with_stmt = partial(v, keywords={"with"}, parens=Ã)
- self.visit_funcdef = partial(v, keywords={"def"}, parens=Ã)
- self.visit_classdef = partial(v, keywords={"class"}, parens=Ã)
- self.visit_expr_stmt = partial(v, keywords=Ã, parens=ASSIGNMENTS)
- self.visit_return_stmt = partial(v, keywords={"return"}, parens={"return"})
- self.visit_import_from = partial(v, keywords=Ã, parens={"import"})
- self.visit_del_stmt = partial(v, keywords=Ã, parens={"del"})
- self.visit_async_funcdef = self.visit_async_stmt
- self.visit_decorated = self.visit_decorators
-
-
-IMPLICIT_TUPLE = {syms.testlist, syms.testlist_star_expr, syms.exprlist}
-BRACKET = {token.LPAR: token.RPAR, token.LSQB: token.RSQB, token.LBRACE: token.RBRACE}
-OPENING_BRACKETS = set(BRACKET.keys())
-CLOSING_BRACKETS = set(BRACKET.values())
-BRACKETS = OPENING_BRACKETS | CLOSING_BRACKETS
-ALWAYS_NO_SPACE = CLOSING_BRACKETS | {token.COMMA, STANDALONE_COMMENT}
-
-
-def whitespace(leaf: Leaf, *, complex_subscript: bool) -> str: # noqa: C901
- """Return whitespace prefix if needed for the given `leaf`.
-
- `complex_subscript` signals whether the given leaf is part of a subscription
- which has non-trivial arguments, like arithmetic expressions or function calls.
- """
- NO = ""
- SPACE = " "
- DOUBLESPACE = " "
- t = leaf.type
- p = leaf.parent
- v = leaf.value
- if t in ALWAYS_NO_SPACE:
- return NO
-
- if t == token.COMMENT:
- return DOUBLESPACE
-
- assert p is not None, f"INTERNAL ERROR: hand-made leaf without parent: {leaf!r}"
- if t == token.COLON and p.type not in {
- syms.subscript,
- syms.subscriptlist,
- syms.sliceop,
- }:
- return NO
-
- prev = leaf.prev_sibling
- if not prev:
- prevp = preceding_leaf(p)
- if not prevp or prevp.type in OPENING_BRACKETS:
- return NO
-
- if t == token.COLON:
- if prevp.type == token.COLON:
- return NO
-
- elif prevp.type != token.COMMA and not complex_subscript:
- return NO
-
- return SPACE
-
- if prevp.type == token.EQUAL:
- if prevp.parent:
- if prevp.parent.type in {
- syms.arglist,
- syms.argument,
- syms.parameters,
- syms.varargslist,
- }:
- return NO
-
- elif prevp.parent.type == syms.typedargslist:
- # A bit hacky: if the equal sign has whitespace, it means we
- # previously found it's a typed argument. So, we're using
- # that, too.
- return prevp.prefix
-
- elif prevp.type in VARARGS_SPECIALS:
- if is_vararg(prevp, within=VARARGS_PARENTS | UNPACKING_PARENTS):
- return NO
-
- elif prevp.type == token.COLON:
- if prevp.parent and prevp.parent.type in {syms.subscript, syms.sliceop}:
- return SPACE if complex_subscript else NO
-
- elif (
- prevp.parent
- and prevp.parent.type == syms.factor
- and prevp.type in MATH_OPERATORS
- ):
- return NO
-
- elif (
- prevp.type == token.RIGHTSHIFT
- and prevp.parent
- and prevp.parent.type == syms.shift_expr
- and prevp.prev_sibling
- and prevp.prev_sibling.type == token.NAME
- and prevp.prev_sibling.value == "print" # type: ignore
- ):
- # Python 2 print chevron
- return NO
- elif prevp.type == token.AT and p.parent and p.parent.type == syms.decorator:
- # no space in decorators
- return NO
-
- elif prev.type in OPENING_BRACKETS:
- return NO
-
- if p.type in {syms.parameters, syms.arglist}:
- # untyped function signatures or calls
- if not prev or prev.type != token.COMMA:
- return NO
-
- elif p.type == syms.varargslist:
- # lambdas
- if prev and prev.type != token.COMMA:
- return NO
-
- elif p.type == syms.typedargslist:
- # typed function signatures
- if not prev:
- return NO
-
- if t == token.EQUAL:
- if prev.type != syms.tname:
- return NO
-
- elif prev.type == token.EQUAL:
- # A bit hacky: if the equal sign has whitespace, it means we
- # previously found it's a typed argument. So, we're using that, too.
- return prev.prefix
-
- elif prev.type != token.COMMA:
- return NO
-
- elif p.type == syms.tname:
- # type names
- if not prev:
- prevp = preceding_leaf(p)
- if not prevp or prevp.type != token.COMMA:
- return NO
-
- elif p.type == syms.trailer:
- # attributes and calls
- if t == token.LPAR or t == token.RPAR:
- return NO
-
- if not prev:
- if t == token.DOT:
- prevp = preceding_leaf(p)
- if not prevp or prevp.type != token.NUMBER:
- return NO
-
- elif t == token.LSQB:
- return NO
-
- elif prev.type != token.COMMA:
- return NO
-
- elif p.type == syms.argument:
- # single argument
- if t == token.EQUAL:
- return NO
-
- if not prev:
- prevp = preceding_leaf(p)
- if not prevp or prevp.type == token.LPAR:
- return NO
-
- elif prev.type in {token.EQUAL} | VARARGS_SPECIALS:
- return NO
-
- elif p.type == syms.decorator:
- # decorators
- return NO
-
- elif p.type == syms.dotted_name:
- if prev:
- return NO
-
- prevp = preceding_leaf(p)
- if not prevp or prevp.type == token.AT or prevp.type == token.DOT:
- return NO
-
- elif p.type == syms.classdef:
- if t == token.LPAR:
- return NO
-
- if prev and prev.type == token.LPAR:
- return NO
-
- elif p.type in {syms.subscript, syms.sliceop}:
- # indexing
- if not prev:
- assert p.parent is not None, "subscripts are always parented"
- if p.parent.type == syms.subscriptlist:
- return SPACE
-
- return NO
-
- elif not complex_subscript:
- return NO
-
- elif p.type == syms.atom:
- if prev and t == token.DOT:
- # dots, but not the first one.
- return NO
-
- elif p.type == syms.dictsetmaker:
- # dict unpacking
- if prev and prev.type == token.DOUBLESTAR:
- return NO
-
- elif p.type in {syms.factor, syms.star_expr}:
- # unary ops
- if not prev:
- prevp = preceding_leaf(p)
- if not prevp or prevp.type in OPENING_BRACKETS:
- return NO
-
- prevp_parent = prevp.parent
- assert prevp_parent is not None
- if prevp.type == token.COLON and prevp_parent.type in {
- syms.subscript,
- syms.sliceop,
- }:
- return NO
-
- elif prevp.type == token.EQUAL and prevp_parent.type == syms.argument:
- return NO
-
- elif t in {token.NAME, token.NUMBER, token.STRING}:
- return NO
-
- elif p.type == syms.import_from:
- if t == token.DOT:
- if prev and prev.type == token.DOT:
- return NO
-
- elif t == token.NAME:
- if v == "import":
- return SPACE
-
- if prev and prev.type == token.DOT:
- return NO
-
- elif p.type == syms.sliceop:
- return NO
-
- return SPACE
-
-
-def preceding_leaf(node: Optional[LN]) -> Optional[Leaf]:
- """Return the first leaf that precedes `node`, if any."""
- while node:
- res = node.prev_sibling
- if res:
- if isinstance(res, Leaf):
- return res
-
- try:
- return list(res.leaves())[-1]
-
- except IndexError:
- return None
-
- node = node.parent
- return None
-
-
-def prev_siblings_are(node: Optional[LN], tokens: List[Optional[NodeType]]) -> bool:
- """Return if the `node` and its previous siblings match types against the provided
- list of tokens; the provided `node`has its type matched against the last element in
- the list. `None` can be used as the first element to declare that the start of the
- list is anchored at the start of its parent's children."""
- if not tokens:
- return True
- if tokens[-1] is None:
- return node is None
- if not node:
- return False
- if node.type != tokens[-1]:
- return False
- return prev_siblings_are(node.prev_sibling, tokens[:-1])
-
-
-def child_towards(ancestor: Node, descendant: LN) -> Optional[LN]:
- """Return the child of `ancestor` that contains `descendant`."""
- node: Optional[LN] = descendant
- while node and node.parent != ancestor:
- node = node.parent
- return node
-
-
-def container_of(leaf: Leaf) -> LN:
- """Return `leaf` or one of its ancestors that is the topmost container of it.
-
- By "container" we mean a node where `leaf` is the very first child.
- """
- same_prefix = leaf.prefix
- container: LN = leaf
- while container:
- parent = container.parent
- if parent is None:
- break
-
- if parent.children[0].prefix != same_prefix:
- break
-
- if parent.type == syms.file_input:
- break
-
- if parent.prev_sibling is not None and parent.prev_sibling.type in BRACKETS:
- break
-
- container = parent
- return container
-
-
-def is_split_after_delimiter(leaf: Leaf, previous: Optional[Leaf] = None) -> Priority:
- """Return the priority of the `leaf` delimiter, given a line break after it.
-
- The delimiter priorities returned here are from those delimiters that would
- cause a line break after themselves.
-
- Higher numbers are higher priority.
- """
- if leaf.type == token.COMMA:
- return COMMA_PRIORITY
-
- return 0
-
-
-def is_split_before_delimiter(leaf: Leaf, previous: Optional[Leaf] = None) -> Priority:
- """Return the priority of the `leaf` delimiter, given a line break before it.
-
- The delimiter priorities returned here are from those delimiters that would
- cause a line break before themselves.
-
- Higher numbers are higher priority.
- """
- if is_vararg(leaf, within=VARARGS_PARENTS | UNPACKING_PARENTS):
- # * and ** might also be MATH_OPERATORS but in this case they are not.
- # Don't treat them as a delimiter.
- return 0
-
- if (
- leaf.type == token.DOT
- and leaf.parent
- and leaf.parent.type not in {syms.import_from, syms.dotted_name}
- and (previous is None or previous.type in CLOSING_BRACKETS)
- ):
- return DOT_PRIORITY
-
- if (
- leaf.type in MATH_OPERATORS
- and leaf.parent
- and leaf.parent.type not in {syms.factor, syms.star_expr}
- ):
- return MATH_PRIORITIES[leaf.type]
-
- if leaf.type in COMPARATORS:
- return COMPARATOR_PRIORITY
-
- if (
- leaf.type == token.STRING
- and previous is not None
- and previous.type == token.STRING
- ):
- return STRING_PRIORITY
-
- if leaf.type not in {token.NAME, token.ASYNC}:
- return 0
-
- if (
- leaf.value == "for"
- and leaf.parent
- and leaf.parent.type in {syms.comp_for, syms.old_comp_for}
- or leaf.type == token.ASYNC
- ):
- if (
- not isinstance(leaf.prev_sibling, Leaf)
- or leaf.prev_sibling.value != "async"
- ):
- return COMPREHENSION_PRIORITY
-
- if (
- leaf.value == "if"
- and leaf.parent
- and leaf.parent.type in {syms.comp_if, syms.old_comp_if}
- ):
- return COMPREHENSION_PRIORITY
-
- if leaf.value in {"if", "else"} and leaf.parent and leaf.parent.type == syms.test:
- return TERNARY_PRIORITY
-
- if leaf.value == "is":
- return COMPARATOR_PRIORITY
-
- if (
- leaf.value == "in"
- and leaf.parent
- and leaf.parent.type in {syms.comp_op, syms.comparison}
- and not (
- previous is not None
- and previous.type == token.NAME
- and previous.value == "not"
- )
- ):
- return COMPARATOR_PRIORITY
-
- if (
- leaf.value == "not"
- and leaf.parent
- and leaf.parent.type == syms.comp_op
- and not (
- previous is not None
- and previous.type == token.NAME
- and previous.value == "is"
- )
- ):
- return COMPARATOR_PRIORITY
-
- if leaf.value in LOGIC_OPERATORS and leaf.parent:
- return LOGIC_PRIORITY
-
- return 0
-
-
-FMT_OFF = {"# fmt: off", "# fmt:off", "# yapf: disable"}
-FMT_SKIP = {"# fmt: skip", "# fmt:skip"}
-FMT_PASS = {*FMT_OFF, *FMT_SKIP}
-FMT_ON = {"# fmt: on", "# fmt:on", "# yapf: enable"}
-
-
-def generate_comments(leaf: LN) -> Iterator[Leaf]:
- """Clean the prefix of the `leaf` and generate comments from it, if any.
-
- Comments in lib2to3 are shoved into the whitespace prefix. This happens
- in `pgen2/driver.py:Driver.parse_tokens()`. This was a brilliant implementation
- move because it does away with modifying the grammar to include all the
- possible places in which comments can be placed.
-
- The sad consequence for us though is that comments don't "belong" anywhere.
- This is why this function generates simple parentless Leaf objects for
- comments. We simply don't know what the correct parent should be.
-
- No matter though, we can live without this. We really only need to
- differentiate between inline and standalone comments. The latter don't
- share the line with any code.
-
- Inline comments are emitted as regular token.COMMENT leaves. Standalone
- are emitted with a fake STANDALONE_COMMENT token identifier.
- """
- for pc in list_comments(leaf.prefix, is_endmarker=leaf.type == token.ENDMARKER):
- yield Leaf(pc.type, pc.value, prefix="\n" * pc.newlines)
-
-
-@dataclass
-class ProtoComment:
- """Describes a piece of syntax that is a comment.
-
- It's not a :class:`blib2to3.pytree.Leaf` so that:
-
- * it can be cached (`Leaf` objects should not be reused more than once as
- they store their lineno, column, prefix, and parent information);
- * `newlines` and `consumed` fields are kept separate from the `value`. This
- simplifies handling of special marker comments like ``# fmt: off/on``.
- """
-
- type: int # token.COMMENT or STANDALONE_COMMENT
- value: str # content of the comment
- newlines: int # how many newlines before the comment
- consumed: int # how many characters of the original leaf's prefix did we consume
-
-
-@lru_cache(maxsize=4096)
-def list_comments(prefix: str, *, is_endmarker: bool) -> List[ProtoComment]:
- """Return a list of :class:`ProtoComment` objects parsed from the given `prefix`."""
- result: List[ProtoComment] = []
- if not prefix or "#" not in prefix:
- return result
-
- consumed = 0
- nlines = 0
- ignored_lines = 0
- for index, line in enumerate(re.split("\r?\n", prefix)):
- consumed += len(line) + 1 # adding the length of the split '\n'
- line = line.lstrip()
- if not line:
- nlines += 1
- if not line.startswith("#"):
- # Escaped newlines outside of a comment are not really newlines at
- # all. We treat a single-line comment following an escaped newline
- # as a simple trailing comment.
- if line.endswith("\\"):
- ignored_lines += 1
- continue
-
- if index == ignored_lines and not is_endmarker:
- comment_type = token.COMMENT # simple trailing comment
- else:
- comment_type = STANDALONE_COMMENT
- comment = make_comment(line)
- result.append(
- ProtoComment(
- type=comment_type, value=comment, newlines=nlines, consumed=consumed
- )
- )
- nlines = 0
- return result
-
-
-def make_comment(content: str) -> str:
- """Return a consistently formatted comment from the given `content` string.
-
- All comments (except for "##", "#!", "#:", '#'", "#%%") should have a single
- space between the hash sign and the content.
-
- If `content` didn't start with a hash sign, one is provided.
- """
- content = content.rstrip()
- if not content:
- return "#"
-
- if content[0] == "#":
- content = content[1:]
- NON_BREAKING_SPACE = "Â "
- if (
- content
- and content[0] == NON_BREAKING_SPACE
- and not content.lstrip().startswith("type:")
- ):
- content = " " + content[1:] # Replace NBSP by a simple space
- if content and content[0] not in " !:#'%":
- content = " " + content
- return "#" + content
-
-
-def transform_line(
- line: Line, mode: Mode, features: Collection[Feature] = ()
-) -> Iterator[Line]:
- """Transform a `line`, potentially splitting it into many lines.
-
- They should fit in the allotted `line_length` but might not be able to.
-
- `features` are syntactical features that may be used in the output.
- """
- if line.is_comment:
- yield line
- return
-
- line_str = line_to_string(line)
-
- def init_st(ST: Type[StringTransformer]) -> StringTransformer:
- """Initialize StringTransformer"""
- return ST(mode.line_length, mode.string_normalization)
-
- string_merge = init_st(StringMerger)
- string_paren_strip = init_st(StringParenStripper)
- string_split = init_st(StringSplitter)
- string_paren_wrap = init_st(StringParenWrapper)
-
- transformers: List[Transformer]
- if (
- not line.contains_uncollapsable_type_comments()
- and not line.should_split_rhs
- and not line.magic_trailing_comma
- and (
- is_line_short_enough(line, line_length=mode.line_length, line_str=line_str)
- or line.contains_unsplittable_type_ignore()
- )
- and not (line.inside_brackets and line.contains_standalone_comments())
- ):
- # Only apply basic string preprocessing, since lines shouldn't be split here.
- if mode.experimental_string_processing:
- transformers = [string_merge, string_paren_strip]
- else:
- transformers = []
- elif line.is_def:
- transformers = [left_hand_split]
- else:
-
- def rhs(line: Line, features: Collection[Feature]) -> Iterator[Line]:
- """Wraps calls to `right_hand_split`.
-
- The calls increasingly `omit` right-hand trailers (bracket pairs with
- content), meaning the trailers get glued together to split on another
- bracket pair instead.
- """
- for omit in generate_trailers_to_omit(line, mode.line_length):
- lines = list(
- right_hand_split(line, mode.line_length, features, omit=omit)
- )
- # Note: this check is only able to figure out if the first line of the
- # *current* transformation fits in the line length. This is true only
- # for simple cases. All others require running more transforms via
- # `transform_line()`. This check doesn't know if those would succeed.
- if is_line_short_enough(lines[0], line_length=mode.line_length):
- yield from lines
- return
-
- # All splits failed, best effort split with no omits.
- # This mostly happens to multiline strings that are by definition
- # reported as not fitting a single line, as well as lines that contain
- # trailing commas (those have to be exploded).
- yield from right_hand_split(
- line, line_length=mode.line_length, features=features
- )
-
- if mode.experimental_string_processing:
- if line.inside_brackets:
- transformers = [
- string_merge,
- string_paren_strip,
- string_split,
- delimiter_split,
- standalone_comment_split,
- string_paren_wrap,
- rhs,
- ]
- else:
- transformers = [
- string_merge,
- string_paren_strip,
- string_split,
- string_paren_wrap,
- rhs,
- ]
- else:
- if line.inside_brackets:
- transformers = [delimiter_split, standalone_comment_split, rhs]
- else:
- transformers = [rhs]
-
- for transform in transformers:
- # We are accumulating lines in `result` because we might want to abort
- # mission and return the original line in the end, or attempt a different
- # split altogether.
- try:
- result = run_transformer(line, transform, mode, features, line_str=line_str)
- except CannotTransform:
- continue
- else:
- yield from result
- break
-
- else:
- yield line
-
-
-@dataclass # type: ignore
-class StringTransformer(ABC):
- """
- An implementation of the Transformer protocol that relies on its
- subclasses overriding the template methods `do_match(...)` and
- `do_transform(...)`.
-
- This Transformer works exclusively on strings (for example, by merging
- or splitting them).
-
- The following sections can be found among the docstrings of each concrete
- StringTransformer subclass.
-
- Requirements:
- Which requirements must be met of the given Line for this
- StringTransformer to be applied?
-
- Transformations:
- If the given Line meets all of the above requirements, which string
- transformations can you expect to be applied to it by this
- StringTransformer?
-
- Collaborations:
- What contractual agreements does this StringTransformer have with other
- StringTransfomers? Such collaborations should be eliminated/minimized
- as much as possible.
- """
-
- line_length: int
- normalize_strings: bool
- __name__ = "StringTransformer"
-
- @abstractmethod
- def do_match(self, line: Line) -> TMatchResult:
- """
- Returns:
- * Ok(string_idx) such that `line.leaves[string_idx]` is our target
- string, if a match was able to be made.
- OR
- * Err(CannotTransform), if a match was not able to be made.
- """
-
- @abstractmethod
- def do_transform(self, line: Line, string_idx: int) -> Iterator[TResult[Line]]:
- """
- Yields:
- * Ok(new_line) where new_line is the new transformed line.
- OR
- * Err(CannotTransform) if the transformation failed for some reason. The
- `do_match(...)` template method should usually be used to reject
- the form of the given Line, but in some cases it is difficult to
- know whether or not a Line meets the StringTransformer's
- requirements until the transformation is already midway.
-
- Side Effects:
- This method should NOT mutate @line directly, but it MAY mutate the
- Line's underlying Node structure. (WARNING: If the underlying Node
- structure IS altered, then this method should NOT be allowed to
- yield an CannotTransform after that point.)
- """
-
- def __call__(self, line: Line, _features: Collection[Feature]) -> Iterator[Line]:
- """
- StringTransformer instances have a call signature that mirrors that of
- the Transformer type.
-
- Raises:
- CannotTransform(...) if the concrete StringTransformer class is unable
- to transform @line.
- """
- # Optimization to avoid calling `self.do_match(...)` when the line does
- # not contain any string.
- if not any(leaf.type == token.STRING for leaf in line.leaves):
- raise CannotTransform("There are no strings in this line.")
-
- match_result = self.do_match(line)
-
- if isinstance(match_result, Err):
- cant_transform = match_result.err()
- raise CannotTransform(
- f"The string transformer {self.__class__.__name__} does not recognize"
- " this line as one that it can transform."
- ) from cant_transform
-
- string_idx = match_result.ok()
-
- for line_result in self.do_transform(line, string_idx):
- if isinstance(line_result, Err):
- cant_transform = line_result.err()
- raise CannotTransform(
- "StringTransformer failed while attempting to transform string."
- ) from cant_transform
- line = line_result.ok()
- yield line
-
-
-@dataclass
-class CustomSplit:
- """A custom (i.e. manual) string split.
-
- A single CustomSplit instance represents a single substring.
-
- Examples:
- Consider the following string:
- ```
- "Hi there friend."
- " This is a custom"
- f" string {split}."
- ```
-
- This string will correspond to the following three CustomSplit instances:
- ```
- CustomSplit(False, 16)
- CustomSplit(False, 17)
- CustomSplit(True, 16)
- ```
- """
-
- has_prefix: bool
- break_idx: int
-
-
-class CustomSplitMapMixin:
- """
- This mixin class is used to map merged strings to a sequence of
- CustomSplits, which will then be used to re-split the strings iff none of
- the resultant substrings go over the configured max line length.
- """
-
- _Key = Tuple[StringID, str]
- _CUSTOM_SPLIT_MAP: Dict[_Key, Tuple[CustomSplit, ...]] = defaultdict(tuple)
-
- @staticmethod
- def _get_key(string: str) -> "CustomSplitMapMixin._Key":
- """
- Returns:
- A unique identifier that is used internally to map @string to a
- group of custom splits.
- """
- return (id(string), string)
-
- def add_custom_splits(
- self, string: str, custom_splits: Iterable[CustomSplit]
- ) -> None:
- """Custom Split Map Setter Method
-
- Side Effects:
- Adds a mapping from @string to the custom splits @custom_splits.
- """
- key = self._get_key(string)
- self._CUSTOM_SPLIT_MAP[key] = tuple(custom_splits)
-
- def pop_custom_splits(self, string: str) -> List[CustomSplit]:
- """Custom Split Map Getter Method
-
- Returns:
- * A list of the custom splits that are mapped to @string, if any
- exist.
- OR
- * [], otherwise.
-
- Side Effects:
- Deletes the mapping between @string and its associated custom
- splits (which are returned to the caller).
- """
- key = self._get_key(string)
-
- custom_splits = self._CUSTOM_SPLIT_MAP[key]
- del self._CUSTOM_SPLIT_MAP[key]
-
- return list(custom_splits)
-
- def has_custom_splits(self, string: str) -> bool:
- """
- Returns:
- True iff @string is associated with a set of custom splits.
- """
- key = self._get_key(string)
- return key in self._CUSTOM_SPLIT_MAP
-
-
-class StringMerger(CustomSplitMapMixin, StringTransformer):
- """StringTransformer that merges strings together.
-
- Requirements:
- (A) The line contains adjacent strings such that ALL of the validation checks
- listed in StringMerger.__validate_msg(...)'s docstring pass.
- OR
- (B) The line contains a string which uses line continuation backslashes.
-
- Transformations:
- Depending on which of the two requirements above where met, either:
-
- (A) The string group associated with the target string is merged.
- OR
- (B) All line-continuation backslashes are removed from the target string.
-
- Collaborations:
- StringMerger provides custom split information to StringSplitter.
- """
-
- def do_match(self, line: Line) -> TMatchResult:
- LL = line.leaves
-
- is_valid_index = is_valid_index_factory(LL)
-
- for (i, leaf) in enumerate(LL):
- if (
- leaf.type == token.STRING
- and is_valid_index(i + 1)
- and LL[i + 1].type == token.STRING
- ):
- return Ok(i)
-
- if leaf.type == token.STRING and "\\\n" in leaf.value:
- return Ok(i)
-
- return TErr("This line has no strings that need merging.")
-
- def do_transform(self, line: Line, string_idx: int) -> Iterator[TResult[Line]]:
- new_line = line
- rblc_result = self.__remove_backslash_line_continuation_chars(
- new_line, string_idx
- )
- if isinstance(rblc_result, Ok):
- new_line = rblc_result.ok()
-
- msg_result = self.__merge_string_group(new_line, string_idx)
- if isinstance(msg_result, Ok):
- new_line = msg_result.ok()
-
- if isinstance(rblc_result, Err) and isinstance(msg_result, Err):
- msg_cant_transform = msg_result.err()
- rblc_cant_transform = rblc_result.err()
- cant_transform = CannotTransform(
- "StringMerger failed to merge any strings in this line."
- )
-
- # Chain the errors together using `__cause__`.
- msg_cant_transform.__cause__ = rblc_cant_transform
- cant_transform.__cause__ = msg_cant_transform
-
- yield Err(cant_transform)
- else:
- yield Ok(new_line)
-
- @staticmethod
- def __remove_backslash_line_continuation_chars(
- line: Line, string_idx: int
- ) -> TResult[Line]:
- """
- Merge strings that were split across multiple lines using
- line-continuation backslashes.
-
- Returns:
- Ok(new_line), if @line contains backslash line-continuation
- characters.
- OR
- Err(CannotTransform), otherwise.
- """
- LL = line.leaves
-
- string_leaf = LL[string_idx]
- if not (
- string_leaf.type == token.STRING
- and "\\\n" in string_leaf.value
- and not has_triple_quotes(string_leaf.value)
- ):
- return TErr(
- f"String leaf {string_leaf} does not contain any backslash line"
- " continuation characters."
- )
-
- new_line = line.clone()
- new_line.comments = line.comments.copy()
- append_leaves(new_line, line, LL)
-
- new_string_leaf = new_line.leaves[string_idx]
- new_string_leaf.value = new_string_leaf.value.replace("\\\n", "")
-
- return Ok(new_line)
-
- def __merge_string_group(self, line: Line, string_idx: int) -> TResult[Line]:
- """
- Merges string group (i.e. set of adjacent strings) where the first
- string in the group is `line.leaves[string_idx]`.
-
- Returns:
- Ok(new_line), if ALL of the validation checks found in
- __validate_msg(...) pass.
- OR
- Err(CannotTransform), otherwise.
- """
- LL = line.leaves
-
- is_valid_index = is_valid_index_factory(LL)
-
- vresult = self.__validate_msg(line, string_idx)
- if isinstance(vresult, Err):
- return vresult
-
- # If the string group is wrapped inside an Atom node, we must make sure
- # to later replace that Atom with our new (merged) string leaf.
- atom_node = LL[string_idx].parent
-
- # We will place BREAK_MARK in between every two substrings that we
- # merge. We will then later go through our final result and use the
- # various instances of BREAK_MARK we find to add the right values to
- # the custom split map.
- BREAK_MARK = "@@@@@ BLACK BREAKPOINT MARKER @@@@@"
-
- QUOTE = LL[string_idx].value[-1]
-
- def make_naked(string: str, string_prefix: str) -> str:
- """Strip @string (i.e. make it a "naked" string)
-
- Pre-conditions:
- * assert_is_leaf_string(@string)
-
- Returns:
- A string that is identical to @string except that
- @string_prefix has been stripped, the surrounding QUOTE
- characters have been removed, and any remaining QUOTE
- characters have been escaped.
- """
- assert_is_leaf_string(string)
-
- RE_EVEN_BACKSLASHES = r"(?:(?<!\\)(?:\\\\)*)"
- naked_string = string[len(string_prefix) + 1 : -1]
- naked_string = re.sub(
- "(" + RE_EVEN_BACKSLASHES + ")" + QUOTE, r"\1\\" + QUOTE, naked_string
- )
- return naked_string
-
- # Holds the CustomSplit objects that will later be added to the custom
- # split map.
- custom_splits = []
-
- # Temporary storage for the 'has_prefix' part of the CustomSplit objects.
- prefix_tracker = []
-
- # Sets the 'prefix' variable. This is the prefix that the final merged
- # string will have.
- next_str_idx = string_idx
- prefix = ""
- while (
- not prefix
- and is_valid_index(next_str_idx)
- and LL[next_str_idx].type == token.STRING
- ):
- prefix = get_string_prefix(LL[next_str_idx].value)
- next_str_idx += 1
-
- # The next loop merges the string group. The final string will be
- # contained in 'S'.
- #
- # The following convenience variables are used:
- #
- # S: string
- # NS: naked string
- # SS: next string
- # NSS: naked next string
- S = ""
- NS = ""
- num_of_strings = 0
- next_str_idx = string_idx
- while is_valid_index(next_str_idx) and LL[next_str_idx].type == token.STRING:
- num_of_strings += 1
-
- SS = LL[next_str_idx].value
- next_prefix = get_string_prefix(SS)
-
- # If this is an f-string group but this substring is not prefixed
- # with 'f'...
- if "f" in prefix and "f" not in next_prefix:
- # Then we must escape any braces contained in this substring.
- SS = re.subf(r"(\{|\})", "{1}{1}", SS)
-
- NSS = make_naked(SS, next_prefix)
-
- has_prefix = bool(next_prefix)
- prefix_tracker.append(has_prefix)
-
- S = prefix + QUOTE + NS + NSS + BREAK_MARK + QUOTE
- NS = make_naked(S, prefix)
-
- next_str_idx += 1
-
- S_leaf = Leaf(token.STRING, S)
- if self.normalize_strings:
- normalize_string_quotes(S_leaf)
-
- # Fill the 'custom_splits' list with the appropriate CustomSplit objects.
- temp_string = S_leaf.value[len(prefix) + 1 : -1]
- for has_prefix in prefix_tracker:
- mark_idx = temp_string.find(BREAK_MARK)
- assert (
- mark_idx >= 0
- ), "Logic error while filling the custom string breakpoint cache."
-
- temp_string = temp_string[mark_idx + len(BREAK_MARK) :]
- breakpoint_idx = mark_idx + (len(prefix) if has_prefix else 0) + 1
- custom_splits.append(CustomSplit(has_prefix, breakpoint_idx))
-
- string_leaf = Leaf(token.STRING, S_leaf.value.replace(BREAK_MARK, ""))
-
- if atom_node is not None:
- replace_child(atom_node, string_leaf)
-
- # Build the final line ('new_line') that this method will later return.
- new_line = line.clone()
- for (i, leaf) in enumerate(LL):
- if i == string_idx:
- new_line.append(string_leaf)
-
- if string_idx <= i < string_idx + num_of_strings:
- for comment_leaf in line.comments_after(LL[i]):
- new_line.append(comment_leaf, preformatted=True)
- continue
-
- append_leaves(new_line, line, [leaf])
-
- self.add_custom_splits(string_leaf.value, custom_splits)
- return Ok(new_line)
-
- @staticmethod
- def __validate_msg(line: Line, string_idx: int) -> TResult[None]:
- """Validate (M)erge (S)tring (G)roup
-
- Transform-time string validation logic for __merge_string_group(...).
-
- Returns:
- * Ok(None), if ALL validation checks (listed below) pass.
- OR
- * Err(CannotTransform), if any of the following are true:
- - The target string group does not contain ANY stand-alone comments.
- - The target string is not in a string group (i.e. it has no
- adjacent strings).
- - The string group has more than one inline comment.
- - The string group has an inline comment that appears to be a pragma.
- - The set of all string prefixes in the string group is of
- length greater than one and is not equal to {"", "f"}.
- - The string group consists of raw strings.
- """
- # We first check for "inner" stand-alone comments (i.e. stand-alone
- # comments that have a string leaf before them AND after them).
- for inc in [1, -1]:
- i = string_idx
- found_sa_comment = False
- is_valid_index = is_valid_index_factory(line.leaves)
- while is_valid_index(i) and line.leaves[i].type in [
- token.STRING,
- STANDALONE_COMMENT,
- ]:
- if line.leaves[i].type == STANDALONE_COMMENT:
- found_sa_comment = True
- elif found_sa_comment:
- return TErr(
- "StringMerger does NOT merge string groups which contain "
- "stand-alone comments."
- )
-
- i += inc
-
- num_of_inline_string_comments = 0
- set_of_prefixes = set()
- num_of_strings = 0
- for leaf in line.leaves[string_idx:]:
- if leaf.type != token.STRING:
- # If the string group is trailed by a comma, we count the
- # comments trailing the comma to be one of the string group's
- # comments.
- if leaf.type == token.COMMA and id(leaf) in line.comments:
- num_of_inline_string_comments += 1
- break
-
- if has_triple_quotes(leaf.value):
- return TErr("StringMerger does NOT merge multiline strings.")
-
- num_of_strings += 1
- prefix = get_string_prefix(leaf.value)
- if "r" in prefix:
- return TErr("StringMerger does NOT merge raw strings.")
-
- set_of_prefixes.add(prefix)
-
- if id(leaf) in line.comments:
- num_of_inline_string_comments += 1
- if contains_pragma_comment(line.comments[id(leaf)]):
- return TErr("Cannot merge strings which have pragma comments.")
-
- if num_of_strings < 2:
- return TErr(
- f"Not enough strings to merge (num_of_strings={num_of_strings})."
- )
-
- if num_of_inline_string_comments > 1:
- return TErr(
- f"Too many inline string comments ({num_of_inline_string_comments})."
- )
-
- if len(set_of_prefixes) > 1 and set_of_prefixes != {"", "f"}:
- return TErr(f"Too many different prefixes ({set_of_prefixes}).")
-
- return Ok(None)
-
-
-class StringParenStripper(StringTransformer):
- """StringTransformer that strips surrounding parentheses from strings.
-
- Requirements:
- The line contains a string which is surrounded by parentheses and:
- - The target string is NOT the only argument to a function call.
- - The target string is NOT a "pointless" string.
- - If the target string contains a PERCENT, the brackets are not
- preceeded or followed by an operator with higher precedence than
- PERCENT.
-
- Transformations:
- The parentheses mentioned in the 'Requirements' section are stripped.
-
- Collaborations:
- StringParenStripper has its own inherent usefulness, but it is also
- relied on to clean up the parentheses created by StringParenWrapper (in
- the event that they are no longer needed).
- """
-
- def do_match(self, line: Line) -> TMatchResult:
- LL = line.leaves
-
- is_valid_index = is_valid_index_factory(LL)
-
- for (idx, leaf) in enumerate(LL):
- # Should be a string...
- if leaf.type != token.STRING:
- continue
-
- # If this is a "pointless" string...
- if (
- leaf.parent
- and leaf.parent.parent
- and leaf.parent.parent.type == syms.simple_stmt
- ):
- continue
-
- # Should be preceded by a non-empty LPAR...
- if (
- not is_valid_index(idx - 1)
- or LL[idx - 1].type != token.LPAR
- or is_empty_lpar(LL[idx - 1])
- ):
- continue
-
- # That LPAR should NOT be preceded by a function name or a closing
- # bracket (which could be a function which returns a function or a
- # list/dictionary that contains a function)...
- if is_valid_index(idx - 2) and (
- LL[idx - 2].type == token.NAME or LL[idx - 2].type in CLOSING_BRACKETS
- ):
- continue
-
- string_idx = idx
-
- # Skip the string trailer, if one exists.
- string_parser = StringParser()
- next_idx = string_parser.parse(LL, string_idx)
-
- # if the leaves in the parsed string include a PERCENT, we need to
- # make sure the initial LPAR is NOT preceded by an operator with
- # higher or equal precedence to PERCENT
- if is_valid_index(idx - 2):
- # mypy can't quite follow unless we name this
- before_lpar = LL[idx - 2]
- if token.PERCENT in {leaf.type for leaf in LL[idx - 1 : next_idx]} and (
- (
- before_lpar.type
- in {
- token.STAR,
- token.AT,
- token.SLASH,
- token.DOUBLESLASH,
- token.PERCENT,
- token.TILDE,
- token.DOUBLESTAR,
- token.AWAIT,
- token.LSQB,
- token.LPAR,
- }
- )
- or (
- # only unary PLUS/MINUS
- before_lpar.parent
- and before_lpar.parent.type == syms.factor
- and (before_lpar.type in {token.PLUS, token.MINUS})
- )
- ):
- continue
-
- # Should be followed by a non-empty RPAR...
- if (
- is_valid_index(next_idx)
- and LL[next_idx].type == token.RPAR
- and not is_empty_rpar(LL[next_idx])
- ):
- # That RPAR should NOT be followed by anything with higher
- # precedence than PERCENT
- if is_valid_index(next_idx + 1) and LL[next_idx + 1].type in {
- token.DOUBLESTAR,
- token.LSQB,
- token.LPAR,
- token.DOT,
- }:
- continue
-
- return Ok(string_idx)
-
- return TErr("This line has no strings wrapped in parens.")
-
- def do_transform(self, line: Line, string_idx: int) -> Iterator[TResult[Line]]:
- LL = line.leaves
-
- string_parser = StringParser()
- rpar_idx = string_parser.parse(LL, string_idx)
-
- for leaf in (LL[string_idx - 1], LL[rpar_idx]):
- if line.comments_after(leaf):
- yield TErr(
- "Will not strip parentheses which have comments attached to them."
- )
- return
-
- new_line = line.clone()
- new_line.comments = line.comments.copy()
- try:
- append_leaves(new_line, line, LL[: string_idx - 1])
- except BracketMatchError:
- # HACK: I believe there is currently a bug somewhere in
- # right_hand_split() that is causing brackets to not be tracked
- # properly by a shared BracketTracker.
- append_leaves(new_line, line, LL[: string_idx - 1], preformatted=True)
-
- string_leaf = Leaf(token.STRING, LL[string_idx].value)
- LL[string_idx - 1].remove()
- replace_child(LL[string_idx], string_leaf)
- new_line.append(string_leaf)
-
- append_leaves(
- new_line, line, LL[string_idx + 1 : rpar_idx] + LL[rpar_idx + 1 :]
- )
-
- LL[rpar_idx].remove()
-
- yield Ok(new_line)
-
-
-class BaseStringSplitter(StringTransformer):
- """
- Abstract class for StringTransformers which transform a Line's strings by splitting
- them or placing them on their own lines where necessary to avoid going over
- the configured line length.
-
- Requirements:
- * The target string value is responsible for the line going over the
- line length limit. It follows that after all of black's other line
- split methods have been exhausted, this line (or one of the resulting
- lines after all line splits are performed) would still be over the
- line_length limit unless we split this string.
- AND
- * The target string is NOT a "pointless" string (i.e. a string that has
- no parent or siblings).
- AND
- * The target string is not followed by an inline comment that appears
- to be a pragma.
- AND
- * The target string is not a multiline (i.e. triple-quote) string.
- """
-
- @abstractmethod
- def do_splitter_match(self, line: Line) -> TMatchResult:
- """
- BaseStringSplitter asks its clients to override this method instead of
- `StringTransformer.do_match(...)`.
-
- Follows the same protocol as `StringTransformer.do_match(...)`.
-
- Refer to `help(StringTransformer.do_match)` for more information.
- """
-
- def do_match(self, line: Line) -> TMatchResult:
- match_result = self.do_splitter_match(line)
- if isinstance(match_result, Err):
- return match_result
-
- string_idx = match_result.ok()
- vresult = self.__validate(line, string_idx)
- if isinstance(vresult, Err):
- return vresult
-
- return match_result
-
- def __validate(self, line: Line, string_idx: int) -> TResult[None]:
- """
- Checks that @line meets all of the requirements listed in this classes'
- docstring. Refer to `help(BaseStringSplitter)` for a detailed
- description of those requirements.
-
- Returns:
- * Ok(None), if ALL of the requirements are met.
- OR
- * Err(CannotTransform), if ANY of the requirements are NOT met.
- """
- LL = line.leaves
-
- string_leaf = LL[string_idx]
-
- max_string_length = self.__get_max_string_length(line, string_idx)
- if len(string_leaf.value) <= max_string_length:
- return TErr(
- "The string itself is not what is causing this line to be too long."
- )
-
- if not string_leaf.parent or [L.type for L in string_leaf.parent.children] == [
- token.STRING,
- token.NEWLINE,
- ]:
- return TErr(
- f"This string ({string_leaf.value}) appears to be pointless (i.e. has"
- " no parent)."
- )
-
- if id(line.leaves[string_idx]) in line.comments and contains_pragma_comment(
- line.comments[id(line.leaves[string_idx])]
- ):
- return TErr(
- "Line appears to end with an inline pragma comment. Splitting the line"
- " could modify the pragma's behavior."
- )
-
- if has_triple_quotes(string_leaf.value):
- return TErr("We cannot split multiline strings.")
-
- return Ok(None)
-
- def __get_max_string_length(self, line: Line, string_idx: int) -> int:
- """
- Calculates the max string length used when attempting to determine
- whether or not the target string is responsible for causing the line to
- go over the line length limit.
-
- WARNING: This method is tightly coupled to both StringSplitter and
- (especially) StringParenWrapper. There is probably a better way to
- accomplish what is being done here.
-
- Returns:
- max_string_length: such that `line.leaves[string_idx].value >
- max_string_length` implies that the target string IS responsible
- for causing this line to exceed the line length limit.
- """
- LL = line.leaves
-
- is_valid_index = is_valid_index_factory(LL)
-
- # We use the shorthand "WMA4" in comments to abbreviate "We must
- # account for". When giving examples, we use STRING to mean some/any
- # valid string.
- #
- # Finally, we use the following convenience variables:
- #
- # P: The leaf that is before the target string leaf.
- # N: The leaf that is after the target string leaf.
- # NN: The leaf that is after N.
-
- # WMA4 the whitespace at the beginning of the line.
- offset = line.depth * 4
-
- if is_valid_index(string_idx - 1):
- p_idx = string_idx - 1
- if (
- LL[string_idx - 1].type == token.LPAR
- and LL[string_idx - 1].value == ""
- and string_idx >= 2
- ):
- # If the previous leaf is an empty LPAR placeholder, we should skip it.
- p_idx -= 1
-
- P = LL[p_idx]
- if P.type == token.PLUS:
- # WMA4 a space and a '+' character (e.g. `+ STRING`).
- offset += 2
-
- if P.type == token.COMMA:
- # WMA4 a space, a comma, and a closing bracket [e.g. `), STRING`].
- offset += 3
-
- if P.type in [token.COLON, token.EQUAL, token.NAME]:
- # This conditional branch is meant to handle dictionary keys,
- # variable assignments, 'return STRING' statement lines, and
- # 'else STRING' ternary expression lines.
-
- # WMA4 a single space.
- offset += 1
-
- # WMA4 the lengths of any leaves that came before that space,
- # but after any closing bracket before that space.
- for leaf in reversed(LL[: p_idx + 1]):
- offset += len(str(leaf))
- if leaf.type in CLOSING_BRACKETS:
- break
-
- if is_valid_index(string_idx + 1):
- N = LL[string_idx + 1]
- if N.type == token.RPAR and N.value == "" and len(LL) > string_idx + 2:
- # If the next leaf is an empty RPAR placeholder, we should skip it.
- N = LL[string_idx + 2]
-
- if N.type == token.COMMA:
- # WMA4 a single comma at the end of the string (e.g `STRING,`).
- offset += 1
-
- if is_valid_index(string_idx + 2):
- NN = LL[string_idx + 2]
-
- if N.type == token.DOT and NN.type == token.NAME:
- # This conditional branch is meant to handle method calls invoked
- # off of a string literal up to and including the LPAR character.
-
- # WMA4 the '.' character.
- offset += 1
-
- if (
- is_valid_index(string_idx + 3)
- and LL[string_idx + 3].type == token.LPAR
- ):
- # WMA4 the left parenthesis character.
- offset += 1
-
- # WMA4 the length of the method's name.
- offset += len(NN.value)
-
- has_comments = False
- for comment_leaf in line.comments_after(LL[string_idx]):
- if not has_comments:
- has_comments = True
- # WMA4 two spaces before the '#' character.
- offset += 2
-
- # WMA4 the length of the inline comment.
- offset += len(comment_leaf.value)
-
- max_string_length = self.line_length - offset
- return max_string_length
-
-
-class StringSplitter(CustomSplitMapMixin, BaseStringSplitter):
- """
- StringTransformer that splits "atom" strings (i.e. strings which exist on
- lines by themselves).
-
- Requirements:
- * The line consists ONLY of a single string (with the exception of a
- '+' symbol which MAY exist at the start of the line), MAYBE a string
- trailer, and MAYBE a trailing comma.
- AND
- * All of the requirements listed in BaseStringSplitter's docstring.
-
- Transformations:
- The string mentioned in the 'Requirements' section is split into as
- many substrings as necessary to adhere to the configured line length.
-
- In the final set of substrings, no substring should be smaller than
- MIN_SUBSTR_SIZE characters.
-
- The string will ONLY be split on spaces (i.e. each new substring should
- start with a space). Note that the string will NOT be split on a space
- which is escaped with a backslash.
-
- If the string is an f-string, it will NOT be split in the middle of an
- f-expression (e.g. in f"FooBar: {foo() if x else bar()}", {foo() if x
- else bar()} is an f-expression).
-
- If the string that is being split has an associated set of custom split
- records and those custom splits will NOT result in any line going over
- the configured line length, those custom splits are used. Otherwise the
- string is split as late as possible (from left-to-right) while still
- adhering to the transformation rules listed above.
-
- Collaborations:
- StringSplitter relies on StringMerger to construct the appropriate
- CustomSplit objects and add them to the custom split map.
- """
-
- MIN_SUBSTR_SIZE = 6
- # Matches an "f-expression" (e.g. {var}) that might be found in an f-string.
- RE_FEXPR = r"""
- (?<!\{) (?:\{\{)* \{ (?!\{)
- (?:
- [^\{\}]
- | \{\{
- | \}\}
- | (?R)
- )+?
- (?<!\}) \} (?:\}\})* (?!\})
- """
-
- def do_splitter_match(self, line: Line) -> TMatchResult:
- LL = line.leaves
-
- is_valid_index = is_valid_index_factory(LL)
-
- idx = 0
-
- # The first leaf MAY be a '+' symbol...
- if is_valid_index(idx) and LL[idx].type == token.PLUS:
- idx += 1
-
- # The next/first leaf MAY be an empty LPAR...
- if is_valid_index(idx) and is_empty_lpar(LL[idx]):
- idx += 1
-
- # The next/first leaf MUST be a string...
- if not is_valid_index(idx) or LL[idx].type != token.STRING:
- return TErr("Line does not start with a string.")
-
- string_idx = idx
-
- # Skip the string trailer, if one exists.
- string_parser = StringParser()
- idx = string_parser.parse(LL, string_idx)
-
- # That string MAY be followed by an empty RPAR...
- if is_valid_index(idx) and is_empty_rpar(LL[idx]):
- idx += 1
-
- # That string / empty RPAR leaf MAY be followed by a comma...
- if is_valid_index(idx) and LL[idx].type == token.COMMA:
- idx += 1
-
- # But no more leaves are allowed...
- if is_valid_index(idx):
- return TErr("This line does not end with a string.")
-
- return Ok(string_idx)
-
- def do_transform(self, line: Line, string_idx: int) -> Iterator[TResult[Line]]:
- LL = line.leaves
-
- QUOTE = LL[string_idx].value[-1]
-
- is_valid_index = is_valid_index_factory(LL)
- insert_str_child = insert_str_child_factory(LL[string_idx])
-
- prefix = get_string_prefix(LL[string_idx].value)
-
- # We MAY choose to drop the 'f' prefix from substrings that don't
- # contain any f-expressions, but ONLY if the original f-string
- # contains at least one f-expression. Otherwise, we will alter the AST
- # of the program.
- drop_pointless_f_prefix = ("f" in prefix) and re.search(
- self.RE_FEXPR, LL[string_idx].value, re.VERBOSE
- )
-
- first_string_line = True
- starts_with_plus = LL[0].type == token.PLUS
-
- def line_needs_plus() -> bool:
- return first_string_line and starts_with_plus
-
- def maybe_append_plus(new_line: Line) -> None:
- """
- Side Effects:
- If @line starts with a plus and this is the first line we are
- constructing, this function appends a PLUS leaf to @new_line
- and replaces the old PLUS leaf in the node structure. Otherwise
- this function does nothing.
- """
- if line_needs_plus():
- plus_leaf = Leaf(token.PLUS, "+")
- replace_child(LL[0], plus_leaf)
- new_line.append(plus_leaf)
-
- ends_with_comma = (
- is_valid_index(string_idx + 1) and LL[string_idx + 1].type == token.COMMA
- )
-
- def max_last_string() -> int:
- """
- Returns:
- The max allowed length of the string value used for the last
- line we will construct.
- """
- result = self.line_length
- result -= line.depth * 4
- result -= 1 if ends_with_comma else 0
- result -= 2 if line_needs_plus() else 0
- return result
-
- # --- Calculate Max Break Index (for string value)
- # We start with the line length limit
- max_break_idx = self.line_length
- # The last index of a string of length N is N-1.
- max_break_idx -= 1
- # Leading whitespace is not present in the string value (e.g. Leaf.value).
- max_break_idx -= line.depth * 4
- if max_break_idx < 0:
- yield TErr(
- f"Unable to split {LL[string_idx].value} at such high of a line depth:"
- f" {line.depth}"
- )
- return
-
- # Check if StringMerger registered any custom splits.
- custom_splits = self.pop_custom_splits(LL[string_idx].value)
- # We use them ONLY if none of them would produce lines that exceed the
- # line limit.
- use_custom_breakpoints = bool(
- custom_splits
- and all(csplit.break_idx <= max_break_idx for csplit in custom_splits)
- )
-
- # Temporary storage for the remaining chunk of the string line that
- # can't fit onto the line currently being constructed.
- rest_value = LL[string_idx].value
-
- def more_splits_should_be_made() -> bool:
- """
- Returns:
- True iff `rest_value` (the remaining string value from the last
- split), should be split again.
- """
- if use_custom_breakpoints:
- return len(custom_splits) > 1
- else:
- return len(rest_value) > max_last_string()
-
- string_line_results: List[Ok[Line]] = []
- while more_splits_should_be_made():
- if use_custom_breakpoints:
- # Custom User Split (manual)
- csplit = custom_splits.pop(0)
- break_idx = csplit.break_idx
- else:
- # Algorithmic Split (automatic)
- max_bidx = max_break_idx - 2 if line_needs_plus() else max_break_idx
- maybe_break_idx = self.__get_break_idx(rest_value, max_bidx)
- if maybe_break_idx is None:
- # If we are unable to algorithmically determine a good split
- # and this string has custom splits registered to it, we
- # fall back to using them--which means we have to start
- # over from the beginning.
- if custom_splits:
- rest_value = LL[string_idx].value
- string_line_results = []
- first_string_line = True
- use_custom_breakpoints = True
- continue
-
- # Otherwise, we stop splitting here.
- break
-
- break_idx = maybe_break_idx
-
- # --- Construct `next_value`
- next_value = rest_value[:break_idx] + QUOTE
- if (
- # Are we allowed to try to drop a pointless 'f' prefix?
- drop_pointless_f_prefix
- # If we are, will we be successful?
- and next_value != self.__normalize_f_string(next_value, prefix)
- ):
- # If the current custom split did NOT originally use a prefix,
- # then `csplit.break_idx` will be off by one after removing
- # the 'f' prefix.
- break_idx = (
- break_idx + 1
- if use_custom_breakpoints and not csplit.has_prefix
- else break_idx
- )
- next_value = rest_value[:break_idx] + QUOTE
- next_value = self.__normalize_f_string(next_value, prefix)
-
- # --- Construct `next_leaf`
- next_leaf = Leaf(token.STRING, next_value)
- insert_str_child(next_leaf)
- self.__maybe_normalize_string_quotes(next_leaf)
-
- # --- Construct `next_line`
- next_line = line.clone()
- maybe_append_plus(next_line)
- next_line.append(next_leaf)
- string_line_results.append(Ok(next_line))
-
- rest_value = prefix + QUOTE + rest_value[break_idx:]
- first_string_line = False
-
- yield from string_line_results
-
- if drop_pointless_f_prefix:
- rest_value = self.__normalize_f_string(rest_value, prefix)
-
- rest_leaf = Leaf(token.STRING, rest_value)
- insert_str_child(rest_leaf)
-
- # NOTE: I could not find a test case that verifies that the following
- # line is actually necessary, but it seems to be. Otherwise we risk
- # not normalizing the last substring, right?
- self.__maybe_normalize_string_quotes(rest_leaf)
-
- last_line = line.clone()
- maybe_append_plus(last_line)
-
- # If there are any leaves to the right of the target string...
- if is_valid_index(string_idx + 1):
- # We use `temp_value` here to determine how long the last line
- # would be if we were to append all the leaves to the right of the
- # target string to the last string line.
- temp_value = rest_value
- for leaf in LL[string_idx + 1 :]:
- temp_value += str(leaf)
- if leaf.type == token.LPAR:
- break
-
- # Try to fit them all on the same line with the last substring...
- if (
- len(temp_value) <= max_last_string()
- or LL[string_idx + 1].type == token.COMMA
- ):
- last_line.append(rest_leaf)
- append_leaves(last_line, line, LL[string_idx + 1 :])
- yield Ok(last_line)
- # Otherwise, place the last substring on one line and everything
- # else on a line below that...
- else:
- last_line.append(rest_leaf)
- yield Ok(last_line)
-
- non_string_line = line.clone()
- append_leaves(non_string_line, line, LL[string_idx + 1 :])
- yield Ok(non_string_line)
- # Else the target string was the last leaf...
- else:
- last_line.append(rest_leaf)
- last_line.comments = line.comments.copy()
- yield Ok(last_line)
-
- def __get_break_idx(self, string: str, max_break_idx: int) -> Optional[int]:
- """
- This method contains the algorithm that StringSplitter uses to
- determine which character to split each string at.
-
- Args:
- @string: The substring that we are attempting to split.
- @max_break_idx: The ideal break index. We will return this value if it
- meets all the necessary conditions. In the likely event that it
- doesn't we will try to find the closest index BELOW @max_break_idx
- that does. If that fails, we will expand our search by also
- considering all valid indices ABOVE @max_break_idx.
-
- Pre-Conditions:
- * assert_is_leaf_string(@string)
- * 0 <= @max_break_idx < len(@string)
-
- Returns:
- break_idx, if an index is able to be found that meets all of the
- conditions listed in the 'Transformations' section of this classes'
- docstring.
- OR
- None, otherwise.
- """
- is_valid_index = is_valid_index_factory(string)
-
- assert is_valid_index(max_break_idx)
- assert_is_leaf_string(string)
-
- _fexpr_slices: Optional[List[Tuple[Index, Index]]] = None
-
- def fexpr_slices() -> Iterator[Tuple[Index, Index]]:
- """
- Yields:
- All ranges of @string which, if @string were to be split there,
- would result in the splitting of an f-expression (which is NOT
- allowed).
- """
- nonlocal _fexpr_slices
-
- if _fexpr_slices is None:
- _fexpr_slices = []
- for match in re.finditer(self.RE_FEXPR, string, re.VERBOSE):
- _fexpr_slices.append(match.span())
-
- yield from _fexpr_slices
-
- is_fstring = "f" in get_string_prefix(string)
-
- def breaks_fstring_expression(i: Index) -> bool:
- """
- Returns:
- True iff returning @i would result in the splitting of an
- f-expression (which is NOT allowed).
- """
- if not is_fstring:
- return False
-
- for (start, end) in fexpr_slices():
- if start <= i < end:
- return True
-
- return False
-
- def passes_all_checks(i: Index) -> bool:
- """
- Returns:
- True iff ALL of the conditions listed in the 'Transformations'
- section of this classes' docstring would be be met by returning @i.
- """
- is_space = string[i] == " "
-
- is_not_escaped = True
- j = i - 1
- while is_valid_index(j) and string[j] == "\\":
- is_not_escaped = not is_not_escaped
- j -= 1
-
- is_big_enough = (
- len(string[i:]) >= self.MIN_SUBSTR_SIZE
- and len(string[:i]) >= self.MIN_SUBSTR_SIZE
- )
- return (
- is_space
- and is_not_escaped
- and is_big_enough
- and not breaks_fstring_expression(i)
- )
-
- # First, we check all indices BELOW @max_break_idx.
- break_idx = max_break_idx
- while is_valid_index(break_idx - 1) and not passes_all_checks(break_idx):
- break_idx -= 1
-
- if not passes_all_checks(break_idx):
- # If that fails, we check all indices ABOVE @max_break_idx.
- #
- # If we are able to find a valid index here, the next line is going
- # to be longer than the specified line length, but it's probably
- # better than doing nothing at all.
- break_idx = max_break_idx + 1
- while is_valid_index(break_idx + 1) and not passes_all_checks(break_idx):
- break_idx += 1
-
- if not is_valid_index(break_idx) or not passes_all_checks(break_idx):
- return None
-
- return break_idx
-
- def __maybe_normalize_string_quotes(self, leaf: Leaf) -> None:
- if self.normalize_strings:
- normalize_string_quotes(leaf)
-
- def __normalize_f_string(self, string: str, prefix: str) -> str:
- """
- Pre-Conditions:
- * assert_is_leaf_string(@string)
-
- Returns:
- * If @string is an f-string that contains no f-expressions, we
- return a string identical to @string except that the 'f' prefix
- has been stripped and all double braces (i.e. '{{' or '}}') have
- been normalized (i.e. turned into '{' or '}').
- OR
- * Otherwise, we return @string.
- """
- assert_is_leaf_string(string)
-
- if "f" in prefix and not re.search(self.RE_FEXPR, string, re.VERBOSE):
- new_prefix = prefix.replace("f", "")
-
- temp = string[len(prefix) :]
- temp = re.sub(r"\{\{", "{", temp)
- temp = re.sub(r"\}\}", "}", temp)
- new_string = temp
-
- return f"{new_prefix}{new_string}"
- else:
- return string
-
-
-class StringParenWrapper(CustomSplitMapMixin, BaseStringSplitter):
- """
- StringTransformer that splits non-"atom" strings (i.e. strings that do not
- exist on lines by themselves).
-
- Requirements:
- All of the requirements listed in BaseStringSplitter's docstring in
- addition to the requirements listed below:
-
- * The line is a return/yield statement, which returns/yields a string.
- OR
- * The line is part of a ternary expression (e.g. `x = y if cond else
- z`) such that the line starts with `else <string>`, where <string> is
- some string.
- OR
- * The line is an assert statement, which ends with a string.
- OR
- * The line is an assignment statement (e.g. `x = <string>` or `x +=
- <string>`) such that the variable is being assigned the value of some
- string.
- OR
- * The line is a dictionary key assignment where some valid key is being
- assigned the value of some string.
-
- Transformations:
- The chosen string is wrapped in parentheses and then split at the LPAR.
-
- We then have one line which ends with an LPAR and another line that
- starts with the chosen string. The latter line is then split again at
- the RPAR. This results in the RPAR (and possibly a trailing comma)
- being placed on its own line.
-
- NOTE: If any leaves exist to the right of the chosen string (except
- for a trailing comma, which would be placed after the RPAR), those
- leaves are placed inside the parentheses. In effect, the chosen
- string is not necessarily being "wrapped" by parentheses. We can,
- however, count on the LPAR being placed directly before the chosen
- string.
-
- In other words, StringParenWrapper creates "atom" strings. These
- can then be split again by StringSplitter, if necessary.
-
- Collaborations:
- In the event that a string line split by StringParenWrapper is
- changed such that it no longer needs to be given its own line,
- StringParenWrapper relies on StringParenStripper to clean up the
- parentheses it created.
- """
-
- def do_splitter_match(self, line: Line) -> TMatchResult:
- LL = line.leaves
-
- string_idx = (
- self._return_match(LL)
- or self._else_match(LL)
- or self._assert_match(LL)
- or self._assign_match(LL)
- or self._dict_match(LL)
- )
-
- if string_idx is not None:
- string_value = line.leaves[string_idx].value
- # If the string has no spaces...
- if " " not in string_value:
- # And will still violate the line length limit when split...
- max_string_length = self.line_length - ((line.depth + 1) * 4)
- if len(string_value) > max_string_length:
- # And has no associated custom splits...
- if not self.has_custom_splits(string_value):
- # Then we should NOT put this string on its own line.
- return TErr(
- "We do not wrap long strings in parentheses when the"
- " resultant line would still be over the specified line"
- " length and can't be split further by StringSplitter."
- )
- return Ok(string_idx)
-
- return TErr("This line does not contain any non-atomic strings.")
-
- @staticmethod
- def _return_match(LL: List[Leaf]) -> Optional[int]:
- """
- Returns:
- string_idx such that @LL[string_idx] is equal to our target (i.e.
- matched) string, if this line matches the return/yield statement
- requirements listed in the 'Requirements' section of this classes'
- docstring.
- OR
- None, otherwise.
- """
- # If this line is apart of a return/yield statement and the first leaf
- # contains either the "return" or "yield" keywords...
- if parent_type(LL[0]) in [syms.return_stmt, syms.yield_expr] and LL[
- 0
- ].value in ["return", "yield"]:
- is_valid_index = is_valid_index_factory(LL)
-
- idx = 2 if is_valid_index(1) and is_empty_par(LL[1]) else 1
- # The next visible leaf MUST contain a string...
- if is_valid_index(idx) and LL[idx].type == token.STRING:
- return idx
-
- return None
-
- @staticmethod
- def _else_match(LL: List[Leaf]) -> Optional[int]:
- """
- Returns:
- string_idx such that @LL[string_idx] is equal to our target (i.e.
- matched) string, if this line matches the ternary expression
- requirements listed in the 'Requirements' section of this classes'
- docstring.
- OR
- None, otherwise.
- """
- # If this line is apart of a ternary expression and the first leaf
- # contains the "else" keyword...
- if (
- parent_type(LL[0]) == syms.test
- and LL[0].type == token.NAME
- and LL[0].value == "else"
- ):
- is_valid_index = is_valid_index_factory(LL)
-
- idx = 2 if is_valid_index(1) and is_empty_par(LL[1]) else 1
- # The next visible leaf MUST contain a string...
- if is_valid_index(idx) and LL[idx].type == token.STRING:
- return idx
-
- return None
-
- @staticmethod
- def _assert_match(LL: List[Leaf]) -> Optional[int]:
- """
- Returns:
- string_idx such that @LL[string_idx] is equal to our target (i.e.
- matched) string, if this line matches the assert statement
- requirements listed in the 'Requirements' section of this classes'
- docstring.
- OR
- None, otherwise.
- """
- # If this line is apart of an assert statement and the first leaf
- # contains the "assert" keyword...
- if parent_type(LL[0]) == syms.assert_stmt and LL[0].value == "assert":
- is_valid_index = is_valid_index_factory(LL)
-
- for (i, leaf) in enumerate(LL):
- # We MUST find a comma...
- if leaf.type == token.COMMA:
- idx = i + 2 if is_empty_par(LL[i + 1]) else i + 1
-
- # That comma MUST be followed by a string...
- if is_valid_index(idx) and LL[idx].type == token.STRING:
- string_idx = idx
-
- # Skip the string trailer, if one exists.
- string_parser = StringParser()
- idx = string_parser.parse(LL, string_idx)
-
- # But no more leaves are allowed...
- if not is_valid_index(idx):
- return string_idx
-
- return None
-
- @staticmethod
- def _assign_match(LL: List[Leaf]) -> Optional[int]:
- """
- Returns:
- string_idx such that @LL[string_idx] is equal to our target (i.e.
- matched) string, if this line matches the assignment statement
- requirements listed in the 'Requirements' section of this classes'
- docstring.
- OR
- None, otherwise.
- """
- # If this line is apart of an expression statement or is a function
- # argument AND the first leaf contains a variable name...
- if (
- parent_type(LL[0]) in [syms.expr_stmt, syms.argument, syms.power]
- and LL[0].type == token.NAME
- ):
- is_valid_index = is_valid_index_factory(LL)
-
- for (i, leaf) in enumerate(LL):
- # We MUST find either an '=' or '+=' symbol...
- if leaf.type in [token.EQUAL, token.PLUSEQUAL]:
- idx = i + 2 if is_empty_par(LL[i + 1]) else i + 1
-
- # That symbol MUST be followed by a string...
- if is_valid_index(idx) and LL[idx].type == token.STRING:
- string_idx = idx
-
- # Skip the string trailer, if one exists.
- string_parser = StringParser()
- idx = string_parser.parse(LL, string_idx)
-
- # The next leaf MAY be a comma iff this line is apart
- # of a function argument...
- if (
- parent_type(LL[0]) == syms.argument
- and is_valid_index(idx)
- and LL[idx].type == token.COMMA
- ):
- idx += 1
-
- # But no more leaves are allowed...
- if not is_valid_index(idx):
- return string_idx
-
- return None
-
- @staticmethod
- def _dict_match(LL: List[Leaf]) -> Optional[int]:
- """
- Returns:
- string_idx such that @LL[string_idx] is equal to our target (i.e.
- matched) string, if this line matches the dictionary key assignment
- statement requirements listed in the 'Requirements' section of this
- classes' docstring.
- OR
- None, otherwise.
- """
- # If this line is apart of a dictionary key assignment...
- if syms.dictsetmaker in [parent_type(LL[0]), parent_type(LL[0].parent)]:
- is_valid_index = is_valid_index_factory(LL)
-
- for (i, leaf) in enumerate(LL):
- # We MUST find a colon...
- if leaf.type == token.COLON:
- idx = i + 2 if is_empty_par(LL[i + 1]) else i + 1
-
- # That colon MUST be followed by a string...
- if is_valid_index(idx) and LL[idx].type == token.STRING:
- string_idx = idx
-
- # Skip the string trailer, if one exists.
- string_parser = StringParser()
- idx = string_parser.parse(LL, string_idx)
-
- # That string MAY be followed by a comma...
- if is_valid_index(idx) and LL[idx].type == token.COMMA:
- idx += 1
-
- # But no more leaves are allowed...
- if not is_valid_index(idx):
- return string_idx
-
- return None
-
- def do_transform(self, line: Line, string_idx: int) -> Iterator[TResult[Line]]:
- LL = line.leaves
-
- is_valid_index = is_valid_index_factory(LL)
- insert_str_child = insert_str_child_factory(LL[string_idx])
-
- comma_idx = -1
- ends_with_comma = False
- if LL[comma_idx].type == token.COMMA:
- ends_with_comma = True
-
- leaves_to_steal_comments_from = [LL[string_idx]]
- if ends_with_comma:
- leaves_to_steal_comments_from.append(LL[comma_idx])
-
- # --- First Line
- first_line = line.clone()
- left_leaves = LL[:string_idx]
-
- # We have to remember to account for (possibly invisible) LPAR and RPAR
- # leaves that already wrapped the target string. If these leaves do
- # exist, we will replace them with our own LPAR and RPAR leaves.
- old_parens_exist = False
- if left_leaves and left_leaves[-1].type == token.LPAR:
- old_parens_exist = True
- leaves_to_steal_comments_from.append(left_leaves[-1])
- left_leaves.pop()
-
- append_leaves(first_line, line, left_leaves)
-
- lpar_leaf = Leaf(token.LPAR, "(")
- if old_parens_exist:
- replace_child(LL[string_idx - 1], lpar_leaf)
- else:
- insert_str_child(lpar_leaf)
- first_line.append(lpar_leaf)
-
- # We throw inline comments that were originally to the right of the
- # target string to the top line. They will now be shown to the right of
- # the LPAR.
- for leaf in leaves_to_steal_comments_from:
- for comment_leaf in line.comments_after(leaf):
- first_line.append(comment_leaf, preformatted=True)
-
- yield Ok(first_line)
-
- # --- Middle (String) Line
- # We only need to yield one (possibly too long) string line, since the
- # `StringSplitter` will break it down further if necessary.
- string_value = LL[string_idx].value
- string_line = Line(
- mode=line.mode,
- depth=line.depth + 1,
- inside_brackets=True,
- should_split_rhs=line.should_split_rhs,
- magic_trailing_comma=line.magic_trailing_comma,
- )
- string_leaf = Leaf(token.STRING, string_value)
- insert_str_child(string_leaf)
- string_line.append(string_leaf)
-
- old_rpar_leaf = None
- if is_valid_index(string_idx + 1):
- right_leaves = LL[string_idx + 1 :]
- if ends_with_comma:
- right_leaves.pop()
-
- if old_parens_exist:
- assert (
- right_leaves and right_leaves[-1].type == token.RPAR
- ), "Apparently, old parentheses do NOT exist?!"
- old_rpar_leaf = right_leaves.pop()
-
- append_leaves(string_line, line, right_leaves)
-
- yield Ok(string_line)
-
- # --- Last Line
- last_line = line.clone()
- last_line.bracket_tracker = first_line.bracket_tracker
-
- new_rpar_leaf = Leaf(token.RPAR, ")")
- if old_rpar_leaf is not None:
- replace_child(old_rpar_leaf, new_rpar_leaf)
- else:
- insert_str_child(new_rpar_leaf)
- last_line.append(new_rpar_leaf)
-
- # If the target string ended with a comma, we place this comma to the
- # right of the RPAR on the last line.
- if ends_with_comma:
- comma_leaf = Leaf(token.COMMA, ",")
- replace_child(LL[comma_idx], comma_leaf)
- last_line.append(comma_leaf)
-
- yield Ok(last_line)
-
-
-class StringParser:
- """
- A state machine that aids in parsing a string's "trailer", which can be
- either non-existent, an old-style formatting sequence (e.g. `% varX` or `%
- (varX, varY)`), or a method-call / attribute access (e.g. `.format(varX,
- varY)`).
-
- NOTE: A new StringParser object MUST be instantiated for each string
- trailer we need to parse.
-
- Examples:
- We shall assume that `line` equals the `Line` object that corresponds
- to the following line of python code:
- ```
- x = "Some {}.".format("String") + some_other_string
- ```
-
- Furthermore, we will assume that `string_idx` is some index such that:
- ```
- assert line.leaves[string_idx].value == "Some {}."
- ```
-
- The following code snippet then holds:
- ```
- string_parser = StringParser()
- idx = string_parser.parse(line.leaves, string_idx)
- assert line.leaves[idx].type == token.PLUS
- ```
- """
-
- DEFAULT_TOKEN = -1
-
- # String Parser States
- START = 1
- DOT = 2
- NAME = 3
- PERCENT = 4
- SINGLE_FMT_ARG = 5
- LPAR = 6
- RPAR = 7
- DONE = 8
-
- # Lookup Table for Next State
- _goto: Dict[Tuple[ParserState, NodeType], ParserState] = {
- # A string trailer may start with '.' OR '%'.
- (START, token.DOT): DOT,
- (START, token.PERCENT): PERCENT,
- (START, DEFAULT_TOKEN): DONE,
- # A '.' MUST be followed by an attribute or method name.
- (DOT, token.NAME): NAME,
- # A method name MUST be followed by an '(', whereas an attribute name
- # is the last symbol in the string trailer.
- (NAME, token.LPAR): LPAR,
- (NAME, DEFAULT_TOKEN): DONE,
- # A '%' symbol can be followed by an '(' or a single argument (e.g. a
- # string or variable name).
- (PERCENT, token.LPAR): LPAR,
- (PERCENT, DEFAULT_TOKEN): SINGLE_FMT_ARG,
- # If a '%' symbol is followed by a single argument, that argument is
- # the last leaf in the string trailer.
- (SINGLE_FMT_ARG, DEFAULT_TOKEN): DONE,
- # If present, a ')' symbol is the last symbol in a string trailer.
- # (NOTE: LPARS and nested RPARS are not included in this lookup table,
- # since they are treated as a special case by the parsing logic in this
- # classes' implementation.)
- (RPAR, DEFAULT_TOKEN): DONE,
- }
-
- def __init__(self) -> None:
- self._state = self.START
- self._unmatched_lpars = 0
-
- def parse(self, leaves: List[Leaf], string_idx: int) -> int:
- """
- Pre-conditions:
- * @leaves[@string_idx].type == token.STRING
-
- Returns:
- The index directly after the last leaf which is apart of the string
- trailer, if a "trailer" exists.
- OR
- @string_idx + 1, if no string "trailer" exists.
- """
- assert leaves[string_idx].type == token.STRING
-
- idx = string_idx + 1
- while idx < len(leaves) and self._next_state(leaves[idx]):
- idx += 1
- return idx
-
- def _next_state(self, leaf: Leaf) -> bool:
- """
- Pre-conditions:
- * On the first call to this function, @leaf MUST be the leaf that
- was directly after the string leaf in question (e.g. if our target
- string is `line.leaves[i]` then the first call to this method must
- be `line.leaves[i + 1]`).
- * On the next call to this function, the leaf parameter passed in
- MUST be the leaf directly following @leaf.
-
- Returns:
- True iff @leaf is apart of the string's trailer.
- """
- # We ignore empty LPAR or RPAR leaves.
- if is_empty_par(leaf):
- return True
-
- next_token = leaf.type
- if next_token == token.LPAR:
- self._unmatched_lpars += 1
-
- current_state = self._state
-
- # The LPAR parser state is a special case. We will return True until we
- # find the matching RPAR token.
- if current_state == self.LPAR:
- if next_token == token.RPAR:
- self._unmatched_lpars -= 1
- if self._unmatched_lpars == 0:
- self._state = self.RPAR
- # Otherwise, we use a lookup table to determine the next state.
- else:
- # If the lookup table matches the current state to the next
- # token, we use the lookup table.
- if (current_state, next_token) in self._goto:
- self._state = self._goto[current_state, next_token]
- else:
- # Otherwise, we check if a the current state was assigned a
- # default.
- if (current_state, self.DEFAULT_TOKEN) in self._goto:
- self._state = self._goto[current_state, self.DEFAULT_TOKEN]
- # If no default has been assigned, then this parser has a logic
- # error.
- else:
- raise RuntimeError(f"{self.__class__.__name__} LOGIC ERROR!")
-
- if self._state == self.DONE:
- return False
-
- return True
-
-
-def TErr(err_msg: str) -> Err[CannotTransform]:
- """(T)ransform Err
-
- Convenience function used when working with the TResult type.
- """
- cant_transform = CannotTransform(err_msg)
- return Err(cant_transform)
-
-
-def contains_pragma_comment(comment_list: List[Leaf]) -> bool:
- """
- Returns:
- True iff one of the comments in @comment_list is a pragma used by one
- of the more common static analysis tools for python (e.g. mypy, flake8,
- pylint).
- """
- for comment in comment_list:
- if comment.value.startswith(("# type:", "# noqa", "# pylint:")):
- return True
-
- return False
-
-
-def insert_str_child_factory(string_leaf: Leaf) -> Callable[[LN], None]:
- """
- Factory for a convenience function that is used to orphan @string_leaf
- and then insert multiple new leaves into the same part of the node
- structure that @string_leaf had originally occupied.
-
- Examples:
- Let `string_leaf = Leaf(token.STRING, '"foo"')` and `N =
- string_leaf.parent`. Assume the node `N` has the following
- original structure:
-
- Node(
- expr_stmt, [
- Leaf(NAME, 'x'),
- Leaf(EQUAL, '='),
- Leaf(STRING, '"foo"'),
- ]
- )
-
- We then run the code snippet shown below.
- ```
- insert_str_child = insert_str_child_factory(string_leaf)
-
- lpar = Leaf(token.LPAR, '(')
- insert_str_child(lpar)
-
- bar = Leaf(token.STRING, '"bar"')
- insert_str_child(bar)
-
- rpar = Leaf(token.RPAR, ')')
- insert_str_child(rpar)
- ```
-
- After which point, it follows that `string_leaf.parent is None` and
- the node `N` now has the following structure:
-
- Node(
- expr_stmt, [
- Leaf(NAME, 'x'),
- Leaf(EQUAL, '='),
- Leaf(LPAR, '('),
- Leaf(STRING, '"bar"'),
- Leaf(RPAR, ')'),
- ]
- )
- """
- string_parent = string_leaf.parent
- string_child_idx = string_leaf.remove()
-
- def insert_str_child(child: LN) -> None:
- nonlocal string_child_idx
-
- assert string_parent is not None
- assert string_child_idx is not None
-
- string_parent.insert_child(string_child_idx, child)
- string_child_idx += 1
-
- return insert_str_child
-
-
-def has_triple_quotes(string: str) -> bool:
- """
- Returns:
- True iff @string starts with three quotation characters.
- """
- raw_string = string.lstrip(STRING_PREFIX_CHARS)
- return raw_string[:3] in {'"""', "'''"}
-
-
-def parent_type(node: Optional[LN]) -> Optional[NodeType]:
- """
- Returns:
- @node.parent.type, if @node is not None and has a parent.
- OR
- None, otherwise.
- """
- if node is None or node.parent is None:
- return None
-
- return node.parent.type
-
-
-def is_empty_par(leaf: Leaf) -> bool:
- return is_empty_lpar(leaf) or is_empty_rpar(leaf)
-
-
-def is_empty_lpar(leaf: Leaf) -> bool:
- return leaf.type == token.LPAR and leaf.value == ""
-
-
-def is_empty_rpar(leaf: Leaf) -> bool:
- return leaf.type == token.RPAR and leaf.value == ""
-
-
-def is_valid_index_factory(seq: Sequence[Any]) -> Callable[[int], bool]:
- """
- Examples:
- ```
- my_list = [1, 2, 3]
-
- is_valid_index = is_valid_index_factory(my_list)
-
- assert is_valid_index(0)
- assert is_valid_index(2)
-
- assert not is_valid_index(3)
- assert not is_valid_index(-1)
- ```
- """
-
- def is_valid_index(idx: int) -> bool:
- """
- Returns:
- True iff @idx is positive AND seq[@idx] does NOT raise an
- IndexError.
- """
- return 0 <= idx < len(seq)
-
- return is_valid_index
-
-
-def line_to_string(line: Line) -> str:
- """Returns the string representation of @line.
-
- WARNING: This is known to be computationally expensive.
- """
- return str(line).strip("\n")
-
-
-def append_leaves(
- new_line: Line, old_line: Line, leaves: List[Leaf], preformatted: bool = False
-) -> None:
- """
- Append leaves (taken from @old_line) to @new_line, making sure to fix the
- underlying Node structure where appropriate.
-
- All of the leaves in @leaves are duplicated. The duplicates are then
- appended to @new_line and used to replace their originals in the underlying
- Node structure. Any comments attached to the old leaves are reattached to
- the new leaves.
-
- Pre-conditions:
- set(@leaves) is a subset of set(@old_line.leaves).
- """
- for old_leaf in leaves:
- new_leaf = Leaf(old_leaf.type, old_leaf.value)
- replace_child(old_leaf, new_leaf)
- new_line.append(new_leaf, preformatted=preformatted)
-
- for comment_leaf in old_line.comments_after(old_leaf):
- new_line.append(comment_leaf, preformatted=True)
-
-
-def replace_child(old_child: LN, new_child: LN) -> None:
- """
- Side Effects:
- * If @old_child.parent is set, replace @old_child with @new_child in
- @old_child's underlying Node structure.
- OR
- * Otherwise, this function does nothing.
- """
- parent = old_child.parent
- if not parent:
- return
-
- child_idx = old_child.remove()
- if child_idx is not None:
- parent.insert_child(child_idx, new_child)
-
-
-def get_string_prefix(string: str) -> str:
- """
- Pre-conditions:
- * assert_is_leaf_string(@string)
-
- Returns:
- @string's prefix (e.g. '', 'r', 'f', or 'rf').
- """
- assert_is_leaf_string(string)
-
- prefix = ""
- prefix_idx = 0
- while string[prefix_idx] in STRING_PREFIX_CHARS:
- prefix += string[prefix_idx].lower()
- prefix_idx += 1
-
- return prefix
-
-
-def assert_is_leaf_string(string: str) -> None:
- """
- Checks the pre-condition that @string has the format that you would expect
- of `leaf.value` where `leaf` is some Leaf such that `leaf.type ==
- token.STRING`. A more precise description of the pre-conditions that are
- checked are listed below.
-
- Pre-conditions:
- * @string starts with either ', ", <prefix>', or <prefix>" where
- `set(<prefix>)` is some subset of `set(STRING_PREFIX_CHARS)`.
- * @string ends with a quote character (' or ").
-
- Raises:
- AssertionError(...) if the pre-conditions listed above are not
- satisfied.
- """
- dquote_idx = string.find('"')
- squote_idx = string.find("'")
- if -1 in [dquote_idx, squote_idx]:
- quote_idx = max(dquote_idx, squote_idx)
- else:
- quote_idx = min(squote_idx, dquote_idx)
-
- assert (
- 0 <= quote_idx < len(string) - 1
- ), f"{string!r} is missing a starting quote character (' or \")."
- assert string[-1] in (
- "'",
- '"',
- ), f"{string!r} is missing an ending quote character (' or \")."
- assert set(string[:quote_idx]).issubset(
- set(STRING_PREFIX_CHARS)
- ), f"{set(string[:quote_idx])} is NOT a subset of {set(STRING_PREFIX_CHARS)}."
-
-
-def left_hand_split(line: Line, _features: Collection[Feature] = ()) -> Iterator[Line]:
- """Split line into many lines, starting with the first matching bracket pair.
-
- Note: this usually looks weird, only use this for function definitions.
- Prefer RHS otherwise. This is why this function is not symmetrical with
- :func:`right_hand_split` which also handles optional parentheses.
- """
- tail_leaves: List[Leaf] = []
- body_leaves: List[Leaf] = []
- head_leaves: List[Leaf] = []
- current_leaves = head_leaves
- matching_bracket: Optional[Leaf] = None
- for leaf in line.leaves:
- if (
- current_leaves is body_leaves
- and leaf.type in CLOSING_BRACKETS
- and leaf.opening_bracket is matching_bracket
- ):
- current_leaves = tail_leaves if body_leaves else head_leaves
- current_leaves.append(leaf)
- if current_leaves is head_leaves:
- if leaf.type in OPENING_BRACKETS:
- matching_bracket = leaf
- current_leaves = body_leaves
- if not matching_bracket:
- raise CannotSplit("No brackets found")
-
- head = bracket_split_build_line(head_leaves, line, matching_bracket)
- body = bracket_split_build_line(body_leaves, line, matching_bracket, is_body=True)
- tail = bracket_split_build_line(tail_leaves, line, matching_bracket)
- bracket_split_succeeded_or_raise(head, body, tail)
- for result in (head, body, tail):
- if result:
- yield result
-
-
-def right_hand_split(
- line: Line,
- line_length: int,
- features: Collection[Feature] = (),
- omit: Collection[LeafID] = (),
-) -> Iterator[Line]:
- """Split line into many lines, starting with the last matching bracket pair.
-
- If the split was by optional parentheses, attempt splitting without them, too.
- `omit` is a collection of closing bracket IDs that shouldn't be considered for
- this split.
-
- Note: running this function modifies `bracket_depth` on the leaves of `line`.
- """
- tail_leaves: List[Leaf] = []
- body_leaves: List[Leaf] = []
- head_leaves: List[Leaf] = []
- current_leaves = tail_leaves
- opening_bracket: Optional[Leaf] = None
- closing_bracket: Optional[Leaf] = None
- for leaf in reversed(line.leaves):
- if current_leaves is body_leaves:
- if leaf is opening_bracket:
- current_leaves = head_leaves if body_leaves else tail_leaves
- current_leaves.append(leaf)
- if current_leaves is tail_leaves:
- if leaf.type in CLOSING_BRACKETS and id(leaf) not in omit:
- opening_bracket = leaf.opening_bracket
- closing_bracket = leaf
- current_leaves = body_leaves
- if not (opening_bracket and closing_bracket and head_leaves):
- # If there is no opening or closing_bracket that means the split failed and
- # all content is in the tail. Otherwise, if `head_leaves` are empty, it means
- # the matching `opening_bracket` wasn't available on `line` anymore.
- raise CannotSplit("No brackets found")
-
- tail_leaves.reverse()
- body_leaves.reverse()
- head_leaves.reverse()
- head = bracket_split_build_line(head_leaves, line, opening_bracket)
- body = bracket_split_build_line(body_leaves, line, opening_bracket, is_body=True)
- tail = bracket_split_build_line(tail_leaves, line, opening_bracket)
- bracket_split_succeeded_or_raise(head, body, tail)
- if (
- Feature.FORCE_OPTIONAL_PARENTHESES not in features
- # the opening bracket is an optional paren
- and opening_bracket.type == token.LPAR
- and not opening_bracket.value
- # the closing bracket is an optional paren
- and closing_bracket.type == token.RPAR
- and not closing_bracket.value
- # it's not an import (optional parens are the only thing we can split on
- # in this case; attempting a split without them is a waste of time)
- and not line.is_import
- # there are no standalone comments in the body
- and not body.contains_standalone_comments(0)
- # and we can actually remove the parens
- and can_omit_invisible_parens(body, line_length, omit_on_explode=omit)
- ):
- omit = {id(closing_bracket), *omit}
- try:
- yield from right_hand_split(line, line_length, features=features, omit=omit)
- return
-
- except CannotSplit:
- if not (
- can_be_split(body)
- or is_line_short_enough(body, line_length=line_length)
- ):
- raise CannotSplit(
- "Splitting failed, body is still too long and can't be split."
- )
-
- elif head.contains_multiline_strings() or tail.contains_multiline_strings():
- raise CannotSplit(
- "The current optional pair of parentheses is bound to fail to"
- " satisfy the splitting algorithm because the head or the tail"
- " contains multiline strings which by definition never fit one"
- " line."
- )
-
- ensure_visible(opening_bracket)
- ensure_visible(closing_bracket)
- for result in (head, body, tail):
- if result:
- yield result
-
-
-def bracket_split_succeeded_or_raise(head: Line, body: Line, tail: Line) -> None:
- """Raise :exc:`CannotSplit` if the last left- or right-hand split failed.
-
- Do nothing otherwise.
-
- A left- or right-hand split is based on a pair of brackets. Content before
- (and including) the opening bracket is left on one line, content inside the
- brackets is put on a separate line, and finally content starting with and
- following the closing bracket is put on a separate line.
-
- Those are called `head`, `body`, and `tail`, respectively. If the split
- produced the same line (all content in `head`) or ended up with an empty `body`
- and the `tail` is just the closing bracket, then it's considered failed.
- """
- tail_len = len(str(tail).strip())
- if not body:
- if tail_len == 0:
- raise CannotSplit("Splitting brackets produced the same line")
-
- elif tail_len < 3:
- raise CannotSplit(
- f"Splitting brackets on an empty body to save {tail_len} characters is"
- " not worth it"
- )
-
-
-def bracket_split_build_line(
- leaves: List[Leaf], original: Line, opening_bracket: Leaf, *, is_body: bool = False
-) -> Line:
- """Return a new line with given `leaves` and respective comments from `original`.
-
- If `is_body` is True, the result line is one-indented inside brackets and as such
- has its first leaf's prefix normalized and a trailing comma added when expected.
- """
- result = Line(mode=original.mode, depth=original.depth)
- if is_body:
- result.inside_brackets = True
- result.depth += 1
- if leaves:
- # Since body is a new indent level, remove spurious leading whitespace.
- normalize_prefix(leaves[0], inside_brackets=True)
- # Ensure a trailing comma for imports and standalone function arguments, but
- # be careful not to add one after any comments or within type annotations.
- no_commas = (
- original.is_def
- and opening_bracket.value == "("
- and not any(leaf.type == token.COMMA for leaf in leaves)
- )
-
- if original.is_import or no_commas:
- for i in range(len(leaves) - 1, -1, -1):
- if leaves[i].type == STANDALONE_COMMENT:
- continue
-
- if leaves[i].type != token.COMMA:
- new_comma = Leaf(token.COMMA, ",")
- leaves.insert(i + 1, new_comma)
- break
-
- # Populate the line
- for leaf in leaves:
- result.append(leaf, preformatted=True)
- for comment_after in original.comments_after(leaf):
- result.append(comment_after, preformatted=True)
- if is_body and should_split_line(result, opening_bracket):
- result.should_split_rhs = True
- return result
-
-
-def dont_increase_indentation(split_func: Transformer) -> Transformer:
- """Normalize prefix of the first leaf in every line returned by `split_func`.
-
- This is a decorator over relevant split functions.
- """
-
- @wraps(split_func)
- def split_wrapper(line: Line, features: Collection[Feature] = ()) -> Iterator[Line]:
- for line in split_func(line, features):
- normalize_prefix(line.leaves[0], inside_brackets=True)
- yield line
-
- return split_wrapper
-
-
-@dont_increase_indentation
-def delimiter_split(line: Line, features: Collection[Feature] = ()) -> Iterator[Line]:
- """Split according to delimiters of the highest priority.
-
- If the appropriate Features are given, the split will add trailing commas
- also in function signatures and calls that contain `*` and `**`.
- """
- try:
- last_leaf = line.leaves[-1]
- except IndexError:
- raise CannotSplit("Line empty")
-
- bt = line.bracket_tracker
- try:
- delimiter_priority = bt.max_delimiter_priority(exclude={id(last_leaf)})
- except ValueError:
- raise CannotSplit("No delimiters found")
-
- if delimiter_priority == DOT_PRIORITY:
- if bt.delimiter_count_with_priority(delimiter_priority) == 1:
- raise CannotSplit("Splitting a single attribute from its owner looks wrong")
-
- current_line = Line(
- mode=line.mode, depth=line.depth, inside_brackets=line.inside_brackets
- )
- lowest_depth = sys.maxsize
- trailing_comma_safe = True
-
- def append_to_line(leaf: Leaf) -> Iterator[Line]:
- """Append `leaf` to current line or to new line if appending impossible."""
- nonlocal current_line
- try:
- current_line.append_safe(leaf, preformatted=True)
- except ValueError:
- yield current_line
-
- current_line = Line(
- mode=line.mode, depth=line.depth, inside_brackets=line.inside_brackets
- )
- current_line.append(leaf)
-
- for leaf in line.leaves:
- yield from append_to_line(leaf)
-
- for comment_after in line.comments_after(leaf):
- yield from append_to_line(comment_after)
-
- lowest_depth = min(lowest_depth, leaf.bracket_depth)
- if leaf.bracket_depth == lowest_depth:
- if is_vararg(leaf, within={syms.typedargslist}):
- trailing_comma_safe = (
- trailing_comma_safe and Feature.TRAILING_COMMA_IN_DEF in features
- )
- elif is_vararg(leaf, within={syms.arglist, syms.argument}):
- trailing_comma_safe = (
- trailing_comma_safe and Feature.TRAILING_COMMA_IN_CALL in features
- )
-
- leaf_priority = bt.delimiters.get(id(leaf))
- if leaf_priority == delimiter_priority:
- yield current_line
-
- current_line = Line(
- mode=line.mode, depth=line.depth, inside_brackets=line.inside_brackets
- )
- if current_line:
- if (
- trailing_comma_safe
- and delimiter_priority == COMMA_PRIORITY
- and current_line.leaves[-1].type != token.COMMA
- and current_line.leaves[-1].type != STANDALONE_COMMENT
- ):
- new_comma = Leaf(token.COMMA, ",")
- current_line.append(new_comma)
- yield current_line
-
-
-@dont_increase_indentation
-def standalone_comment_split(
- line: Line, features: Collection[Feature] = ()
-) -> Iterator[Line]:
- """Split standalone comments from the rest of the line."""
- if not line.contains_standalone_comments(0):
- raise CannotSplit("Line does not have any standalone comments")
-
- current_line = Line(
- mode=line.mode, depth=line.depth, inside_brackets=line.inside_brackets
- )
-
- def append_to_line(leaf: Leaf) -> Iterator[Line]:
- """Append `leaf` to current line or to new line if appending impossible."""
- nonlocal current_line
- try:
- current_line.append_safe(leaf, preformatted=True)
- except ValueError:
- yield current_line
-
- current_line = Line(
- line.mode, depth=line.depth, inside_brackets=line.inside_brackets
- )
- current_line.append(leaf)
-
- for leaf in line.leaves:
- yield from append_to_line(leaf)
-
- for comment_after in line.comments_after(leaf):
- yield from append_to_line(comment_after)
-
- if current_line:
- yield current_line
-
-
-def is_import(leaf: Leaf) -> bool:
- """Return True if the given leaf starts an import statement."""
- p = leaf.parent
- t = leaf.type
- v = leaf.value
- return bool(
- t == token.NAME
- and (
- (v == "import" and p and p.type == syms.import_name)
- or (v == "from" and p and p.type == syms.import_from)
- )
- )
-
-
-def is_type_comment(leaf: Leaf, suffix: str = "") -> bool:
- """Return True if the given leaf is a special comment.
- Only returns true for type comments for now."""
- t = leaf.type
- v = leaf.value
- return t in {token.COMMENT, STANDALONE_COMMENT} and v.startswith("# type:" + suffix)
-
-
-def normalize_prefix(leaf: Leaf, *, inside_brackets: bool) -> None:
- """Leave existing extra newlines if not `inside_brackets`. Remove everything
- else.
-
- Note: don't use backslashes for formatting or you'll lose your voting rights.
- """
- if not inside_brackets:
- spl = leaf.prefix.split("#")
- if "\\" not in spl[0]:
- nl_count = spl[-1].count("\n")
- if len(spl) > 1:
- nl_count -= 1
- leaf.prefix = "\n" * nl_count
- return
-
- leaf.prefix = ""
-
-
-def normalize_string_prefix(leaf: Leaf, remove_u_prefix: bool = False) -> None:
- """Make all string prefixes lowercase.
-
- If remove_u_prefix is given, also removes any u prefix from the string.
-
- Note: Mutates its argument.
- """
- match = re.match(r"^([" + STRING_PREFIX_CHARS + r"]*)(.*)$", leaf.value, re.DOTALL)
- assert match is not None, f"failed to match string {leaf.value!r}"
- orig_prefix = match.group(1)
- new_prefix = orig_prefix.replace("F", "f").replace("B", "b").replace("U", "u")
- if remove_u_prefix:
- new_prefix = new_prefix.replace("u", "")
- leaf.value = f"{new_prefix}{match.group(2)}"
-
-
-def normalize_string_quotes(leaf: Leaf) -> None:
- """Prefer double quotes but only if it doesn't cause more escaping.
-
- Adds or removes backslashes as appropriate. Doesn't parse and fix
- strings nested in f-strings (yet).
-
- Note: Mutates its argument.
- """
- value = leaf.value.lstrip(STRING_PREFIX_CHARS)
- if value[:3] == '"""':
- return
-
- elif value[:3] == "'''":
- orig_quote = "'''"
- new_quote = '"""'
- elif value[0] == '"':
- orig_quote = '"'
- new_quote = "'"
- else:
- orig_quote = "'"
- new_quote = '"'
- first_quote_pos = leaf.value.find(orig_quote)
- if first_quote_pos == -1:
- return # There's an internal error
-
- prefix = leaf.value[:first_quote_pos]
- unescaped_new_quote = re.compile(rf"(([^\\]|^)(\\\\)*){new_quote}")
- escaped_new_quote = re.compile(rf"([^\\]|^)\\((?:\\\\)*){new_quote}")
- escaped_orig_quote = re.compile(rf"([^\\]|^)\\((?:\\\\)*){orig_quote}")
- body = leaf.value[first_quote_pos + len(orig_quote) : -len(orig_quote)]
- if "r" in prefix.casefold():
- if unescaped_new_quote.search(body):
- # There's at least one unescaped new_quote in this raw string
- # so converting is impossible
- return
-
- # Do not introduce or remove backslashes in raw strings
- new_body = body
- else:
- # remove unnecessary escapes
- new_body = sub_twice(escaped_new_quote, rf"\1\2{new_quote}", body)
- if body != new_body:
- # Consider the string without unnecessary escapes as the original
- body = new_body
- leaf.value = f"{prefix}{orig_quote}{body}{orig_quote}"
- new_body = sub_twice(escaped_orig_quote, rf"\1\2{orig_quote}", new_body)
- new_body = sub_twice(unescaped_new_quote, rf"\1\\{new_quote}", new_body)
- if "f" in prefix.casefold():
- matches = re.findall(
- r"""
- (?:[^{]|^)\{ # start of the string or a non-{ followed by a single {
- ([^{].*?) # contents of the brackets except if begins with {{
- \}(?:[^}]|$) # A } followed by end of the string or a non-}
- """,
- new_body,
- re.VERBOSE,
- )
- for m in matches:
- if "\\" in str(m):
- # Do not introduce backslashes in interpolated expressions
- return
-
- if new_quote == '"""' and new_body[-1:] == '"':
- # edge case:
- new_body = new_body[:-1] + '\\"'
- orig_escape_count = body.count("\\")
- new_escape_count = new_body.count("\\")
- if new_escape_count > orig_escape_count:
- return # Do not introduce more escaping
-
- if new_escape_count == orig_escape_count and orig_quote == '"':
- return # Prefer double quotes
-
- leaf.value = f"{prefix}{new_quote}{new_body}{new_quote}"
-
-
-def normalize_numeric_literal(leaf: Leaf) -> None:
- """Normalizes numeric (float, int, and complex) literals.
-
- All letters used in the representation are normalized to lowercase (except
- in Python 2 long literals).
- """
- text = leaf.value.lower()
- if text.startswith(("0o", "0b")):
- # Leave octal and binary literals alone.
- pass
- elif text.startswith("0x"):
- text = format_hex(text)
- elif "e" in text:
- text = format_scientific_notation(text)
- elif text.endswith(("j", "l")):
- text = format_long_or_complex_number(text)
- else:
- text = format_float_or_int_string(text)
- leaf.value = text
-
-
-def format_hex(text: str) -> str:
- """
- Formats a hexadecimal string like "0x12B3"
- """
- before, after = text[:2], text[2:]
- return f"{before}{after.upper()}"
-
-
-def format_scientific_notation(text: str) -> str:
- """Formats a numeric string utilizing scentific notation"""
- before, after = text.split("e")
- sign = ""
- if after.startswith("-"):
- after = after[1:]
- sign = "-"
- elif after.startswith("+"):
- after = after[1:]
- before = format_float_or_int_string(before)
- return f"{before}e{sign}{after}"
-
-
-def format_long_or_complex_number(text: str) -> str:
- """Formats a long or complex string like `10L` or `10j`"""
- number = text[:-1]
- suffix = text[-1]
- # Capitalize in "2L" because "l" looks too similar to "1".
- if suffix == "l":
- suffix = "L"
- return f"{format_float_or_int_string(number)}{suffix}"
-
-
-def format_float_or_int_string(text: str) -> str:
- """Formats a float string like "1.0"."""
- if "." not in text:
- return text
-
- before, after = text.split(".")
- return f"{before or 0}.{after or 0}"
-
-
-def normalize_invisible_parens(node: Node, parens_after: Set[str]) -> None:
- """Make existing optional parentheses invisible or create new ones.
-
- `parens_after` is a set of string leaf values immediately after which parens
- should be put.
-
- Standardizes on visible parentheses for single-element tuples, and keeps
- existing visible parentheses for other tuples and generator expressions.
- """
- for pc in list_comments(node.prefix, is_endmarker=False):
- if pc.value in FMT_OFF:
- # This `node` has a prefix with `# fmt: off`, don't mess with parens.
- return
- check_lpar = False
- for index, child in enumerate(list(node.children)):
- # Fixes a bug where invisible parens are not properly stripped from
- # assignment statements that contain type annotations.
- if isinstance(child, Node) and child.type == syms.annassign:
- normalize_invisible_parens(child, parens_after=parens_after)
-
- # Add parentheses around long tuple unpacking in assignments.
- if (
- index == 0
- and isinstance(child, Node)
- and child.type == syms.testlist_star_expr
- ):
- check_lpar = True
-
- if check_lpar:
- if child.type == syms.atom:
- if maybe_make_parens_invisible_in_atom(child, parent=node):
- wrap_in_parentheses(node, child, visible=False)
- elif is_one_tuple(child):
- wrap_in_parentheses(node, child, visible=True)
- elif node.type == syms.import_from:
- # "import from" nodes store parentheses directly as part of
- # the statement
- if child.type == token.LPAR:
- # make parentheses invisible
- child.value = "" # type: ignore
- node.children[-1].value = "" # type: ignore
- elif child.type != token.STAR:
- # insert invisible parentheses
- node.insert_child(index, Leaf(token.LPAR, ""))
- node.append_child(Leaf(token.RPAR, ""))
- break
-
- elif not (isinstance(child, Leaf) and is_multiline_string(child)):
- wrap_in_parentheses(node, child, visible=False)
-
- check_lpar = isinstance(child, Leaf) and child.value in parens_after
-
-
-def normalize_fmt_off(node: Node) -> None:
- """Convert content between `# fmt: off`/`# fmt: on` into standalone comments."""
- try_again = True
- while try_again:
- try_again = convert_one_fmt_off_pair(node)
-
-
-def convert_one_fmt_off_pair(node: Node) -> bool:
- """Convert content of a single `# fmt: off`/`# fmt: on` into a standalone comment.
-
- Returns True if a pair was converted.
- """
- for leaf in node.leaves():
- previous_consumed = 0
- for comment in list_comments(leaf.prefix, is_endmarker=False):
- if comment.value not in FMT_PASS:
- previous_consumed = comment.consumed
- continue
- # We only want standalone comments. If there's no previous leaf or
- # the previous leaf is indentation, it's a standalone comment in
- # disguise.
- if comment.value in FMT_PASS and comment.type != STANDALONE_COMMENT:
- prev = preceding_leaf(leaf)
- if prev:
- if comment.value in FMT_OFF and prev.type not in WHITESPACE:
- continue
- if comment.value in FMT_SKIP and prev.type in WHITESPACE:
- continue
-
- ignored_nodes = list(generate_ignored_nodes(leaf, comment))
- if not ignored_nodes:
- continue
-
- first = ignored_nodes[0] # Can be a container node with the `leaf`.
- parent = first.parent
- prefix = first.prefix
- first.prefix = prefix[comment.consumed :]
- hidden_value = "".join(str(n) for n in ignored_nodes)
- if comment.value in FMT_OFF:
- hidden_value = comment.value + "\n" + hidden_value
- if comment.value in FMT_SKIP:
- hidden_value += " " + comment.value
- if hidden_value.endswith("\n"):
- # That happens when one of the `ignored_nodes` ended with a NEWLINE
- # leaf (possibly followed by a DEDENT).
- hidden_value = hidden_value[:-1]
- first_idx: Optional[int] = None
- for ignored in ignored_nodes:
- index = ignored.remove()
- if first_idx is None:
- first_idx = index
- assert parent is not None, "INTERNAL ERROR: fmt: on/off handling (1)"
- assert first_idx is not None, "INTERNAL ERROR: fmt: on/off handling (2)"
- parent.insert_child(
- first_idx,
- Leaf(
- STANDALONE_COMMENT,
- hidden_value,
- prefix=prefix[:previous_consumed] + "\n" * comment.newlines,
- ),
- )
- return True
-
- return False
-
-
-def generate_ignored_nodes(leaf: Leaf, comment: ProtoComment) -> Iterator[LN]:
- """Starting from the container of `leaf`, generate all leaves until `# fmt: on`.
-
- If comment is skip, returns leaf only.
- Stops at the end of the block.
- """
- container: Optional[LN] = container_of(leaf)
- if comment.value in FMT_SKIP:
- prev_sibling = leaf.prev_sibling
- if comment.value in leaf.prefix and prev_sibling is not None:
- leaf.prefix = leaf.prefix.replace(comment.value, "")
- siblings = [prev_sibling]
- while (
- "\n" not in prev_sibling.prefix
- and prev_sibling.prev_sibling is not None
- ):
- prev_sibling = prev_sibling.prev_sibling
- siblings.insert(0, prev_sibling)
- for sibling in siblings:
- yield sibling
- elif leaf.parent is not None:
- yield leaf.parent
- return
- while container is not None and container.type != token.ENDMARKER:
- if is_fmt_on(container):
- return
-
- # fix for fmt: on in children
- if contains_fmt_on_at_column(container, leaf.column):
- for child in container.children:
- if contains_fmt_on_at_column(child, leaf.column):
- return
- yield child
- else:
- yield container
- container = container.next_sibling
-
-
-def is_fmt_on(container: LN) -> bool:
- """Determine whether formatting is switched on within a container.
- Determined by whether the last `# fmt:` comment is `on` or `off`.
- """
- fmt_on = False
- for comment in list_comments(container.prefix, is_endmarker=False):
- if comment.value in FMT_ON:
- fmt_on = True
- elif comment.value in FMT_OFF:
- fmt_on = False
- return fmt_on
-
-
-def contains_fmt_on_at_column(container: LN, column: int) -> bool:
- """Determine if children at a given column have formatting switched on."""
- for child in container.children:
- if (
- isinstance(child, Node)
- and first_leaf_column(child) == column
- or isinstance(child, Leaf)
- and child.column == column
- ):
- if is_fmt_on(child):
- return True
-
- return False
-
-
-def first_leaf_column(node: Node) -> Optional[int]:
- """Returns the column of the first leaf child of a node."""
- for child in node.children:
- if isinstance(child, Leaf):
- return child.column
- return None
-
-
-def maybe_make_parens_invisible_in_atom(node: LN, parent: LN) -> bool:
- """If it's safe, make the parens in the atom `node` invisible, recursively.
- Additionally, remove repeated, adjacent invisible parens from the atom `node`
- as they are redundant.
-
- Returns whether the node should itself be wrapped in invisible parentheses.
-
- """
-
- if (
- node.type != syms.atom
- or is_empty_tuple(node)
- or is_one_tuple(node)
- or (is_yield(node) and parent.type != syms.expr_stmt)
- or max_delimiter_priority_in_atom(node) >= COMMA_PRIORITY
- ):
- return False
-
- if is_walrus_assignment(node):
- if parent.type in [
- syms.annassign,
- syms.expr_stmt,
- syms.assert_stmt,
- syms.return_stmt,
- # these ones aren't useful to end users, but they do please fuzzers
- syms.for_stmt,
- syms.del_stmt,
- ]:
- return False
-
- first = node.children[0]
- last = node.children[-1]
- if first.type == token.LPAR and last.type == token.RPAR:
- middle = node.children[1]
- # make parentheses invisible
- first.value = "" # type: ignore
- last.value = "" # type: ignore
- maybe_make_parens_invisible_in_atom(middle, parent=parent)
-
- if is_atom_with_invisible_parens(middle):
- # Strip the invisible parens from `middle` by replacing
- # it with the child in-between the invisible parens
- middle.replace(middle.children[1])
-
- return False
-
- return True
-
-
-def is_atom_with_invisible_parens(node: LN) -> bool:
- """Given a `LN`, determines whether it's an atom `node` with invisible
- parens. Useful in dedupe-ing and normalizing parens.
- """
- if isinstance(node, Leaf) or node.type != syms.atom:
- return False
-
- first, last = node.children[0], node.children[-1]
- return (
- isinstance(first, Leaf)
- and first.type == token.LPAR
- and first.value == ""
- and isinstance(last, Leaf)
- and last.type == token.RPAR
- and last.value == ""
- )
-
-
-def is_empty_tuple(node: LN) -> bool:
- """Return True if `node` holds an empty tuple."""
- return (
- node.type == syms.atom
- and len(node.children) == 2
- and node.children[0].type == token.LPAR
- and node.children[1].type == token.RPAR
- )
-
-
-def unwrap_singleton_parenthesis(node: LN) -> Optional[LN]:
- """Returns `wrapped` if `node` is of the shape ( wrapped ).
-
- Parenthesis can be optional. Returns None otherwise"""
- if len(node.children) != 3:
- return None
-
- lpar, wrapped, rpar = node.children
- if not (lpar.type == token.LPAR and rpar.type == token.RPAR):
- return None
-
- return wrapped
-
-
-def first_child_is_arith(node: Node) -> bool:
- """Whether first child is an arithmetic or a binary arithmetic expression"""
- expr_types = {
- syms.arith_expr,
- syms.shift_expr,
- syms.xor_expr,
- syms.and_expr,
- }
- return bool(node.children and node.children[0].type in expr_types)
-
-
-def wrap_in_parentheses(parent: Node, child: LN, *, visible: bool = True) -> None:
- """Wrap `child` in parentheses.
-
- This replaces `child` with an atom holding the parentheses and the old
- child. That requires moving the prefix.
-
- If `visible` is False, the leaves will be valueless (and thus invisible).
- """
- lpar = Leaf(token.LPAR, "(" if visible else "")
- rpar = Leaf(token.RPAR, ")" if visible else "")
- prefix = child.prefix
- child.prefix = ""
- index = child.remove() or 0
- new_child = Node(syms.atom, [lpar, child, rpar])
- new_child.prefix = prefix
- parent.insert_child(index, new_child)
-
-
-def is_one_tuple(node: LN) -> bool:
- """Return True if `node` holds a tuple with one element, with or without parens."""
- if node.type == syms.atom:
- gexp = unwrap_singleton_parenthesis(node)
- if gexp is None or gexp.type != syms.testlist_gexp:
- return False
-
- return len(gexp.children) == 2 and gexp.children[1].type == token.COMMA
-
- return (
- node.type in IMPLICIT_TUPLE
- and len(node.children) == 2
- and node.children[1].type == token.COMMA
- )
-
-
-def is_walrus_assignment(node: LN) -> bool:
- """Return True iff `node` is of the shape ( test := test )"""
- inner = unwrap_singleton_parenthesis(node)
- return inner is not None and inner.type == syms.namedexpr_test
-
-
-def is_simple_decorator_trailer(node: LN, last: bool = False) -> bool:
- """Return True iff `node` is a trailer valid in a simple decorator"""
- return node.type == syms.trailer and (
- (
- len(node.children) == 2
- and node.children[0].type == token.DOT
- and node.children[1].type == token.NAME
- )
- # last trailer can be an argument-less parentheses pair
- or (
- last
- and len(node.children) == 2
- and node.children[0].type == token.LPAR
- and node.children[1].type == token.RPAR
- )
- # last trailer can be arguments
- or (
- last
- and len(node.children) == 3
- and node.children[0].type == token.LPAR
- # and node.children[1].type == syms.argument
- and node.children[2].type == token.RPAR
- )
- )
-
-
-def is_simple_decorator_expression(node: LN) -> bool:
- """Return True iff `node` could be a 'dotted name' decorator
-
- This function takes the node of the 'namedexpr_test' of the new decorator
- grammar and test if it would be valid under the old decorator grammar.
-
- The old grammar was: decorator: @ dotted_name [arguments] NEWLINE
- The new grammar is : decorator: @ namedexpr_test NEWLINE
- """
- if node.type == token.NAME:
- return True
- if node.type == syms.power:
- if node.children:
- return (
- node.children[0].type == token.NAME
- and all(map(is_simple_decorator_trailer, node.children[1:-1]))
- and (
- len(node.children) < 2
- or is_simple_decorator_trailer(node.children[-1], last=True)
- )
- )
- return False
-
-
-def is_yield(node: LN) -> bool:
- """Return True if `node` holds a `yield` or `yield from` expression."""
- if node.type == syms.yield_expr:
- return True
-
- if node.type == token.NAME and node.value == "yield": # type: ignore
- return True
-
- if node.type != syms.atom:
- return False
-
- if len(node.children) != 3:
- return False
-
- lpar, expr, rpar = node.children
- if lpar.type == token.LPAR and rpar.type == token.RPAR:
- return is_yield(expr)
-
- return False
-
-
-def is_vararg(leaf: Leaf, within: Set[NodeType]) -> bool:
- """Return True if `leaf` is a star or double star in a vararg or kwarg.
-
- If `within` includes VARARGS_PARENTS, this applies to function signatures.
- If `within` includes UNPACKING_PARENTS, it applies to right hand-side
- extended iterable unpacking (PEP 3132) and additional unpacking
- generalizations (PEP 448).
- """
- if leaf.type not in VARARGS_SPECIALS or not leaf.parent:
- return False
-
- p = leaf.parent
- if p.type == syms.star_expr:
- # Star expressions are also used as assignment targets in extended
- # iterable unpacking (PEP 3132). See what its parent is instead.
- if not p.parent:
- return False
-
- p = p.parent
-
- return p.type in within
-
-
-def is_multiline_string(leaf: Leaf) -> bool:
- """Return True if `leaf` is a multiline string that actually spans many lines."""
- return has_triple_quotes(leaf.value) and "\n" in leaf.value
-
-
-def is_stub_suite(node: Node) -> bool:
- """Return True if `node` is a suite with a stub body."""
- if (
- len(node.children) != 4
- or node.children[0].type != token.NEWLINE
- or node.children[1].type != token.INDENT
- or node.children[3].type != token.DEDENT
- ):
- return False
-
- return is_stub_body(node.children[2])
-
-
-def is_stub_body(node: LN) -> bool:
- """Return True if `node` is a simple statement containing an ellipsis."""
- if not isinstance(node, Node) or node.type != syms.simple_stmt:
- return False
-
- if len(node.children) != 2:
- return False
-
- child = node.children[0]
- return (
- child.type == syms.atom
- and len(child.children) == 3
- and all(leaf == Leaf(token.DOT, ".") for leaf in child.children)
- )
-
-
-def max_delimiter_priority_in_atom(node: LN) -> Priority:
- """Return maximum delimiter priority inside `node`.
-
- This is specific to atoms with contents contained in a pair of parentheses.
- If `node` isn't an atom or there are no enclosing parentheses, returns 0.
- """
- if node.type != syms.atom:
- return 0
-
- first = node.children[0]
- last = node.children[-1]
- if not (first.type == token.LPAR and last.type == token.RPAR):
- return 0
-
- bt = BracketTracker()
- for c in node.children[1:-1]:
- if isinstance(c, Leaf):
- bt.mark(c)
- else:
- for leaf in c.leaves():
- bt.mark(leaf)
- try:
- return bt.max_delimiter_priority()
-
- except ValueError:
- return 0
-
-
-def ensure_visible(leaf: Leaf) -> None:
- """Make sure parentheses are visible.
-
- They could be invisible as part of some statements (see
- :func:`normalize_invisible_parens` and :func:`visit_import_from`).
- """
- if leaf.type == token.LPAR:
- leaf.value = "("
- elif leaf.type == token.RPAR:
- leaf.value = ")"
-
-
-def should_split_line(line: Line, opening_bracket: Leaf) -> bool:
- """Should `line` be immediately split with `delimiter_split()` after RHS?"""
-
- if not (opening_bracket.parent and opening_bracket.value in "[{("):
- return False
-
- # We're essentially checking if the body is delimited by commas and there's more
- # than one of them (we're excluding the trailing comma and if the delimiter priority
- # is still commas, that means there's more).
- exclude = set()
- trailing_comma = False
- try:
- last_leaf = line.leaves[-1]
- if last_leaf.type == token.COMMA:
- trailing_comma = True
- exclude.add(id(last_leaf))
- max_priority = line.bracket_tracker.max_delimiter_priority(exclude=exclude)
- except (IndexError, ValueError):
- return False
-
- return max_priority == COMMA_PRIORITY and (
- (line.mode.magic_trailing_comma and trailing_comma)
- # always explode imports
- or opening_bracket.parent.type in {syms.atom, syms.import_from}
- )
-
-
-def is_one_tuple_between(opening: Leaf, closing: Leaf, leaves: List[Leaf]) -> bool:
- """Return True if content between `opening` and `closing` looks like a one-tuple."""
- if opening.type != token.LPAR and closing.type != token.RPAR:
- return False
-
- depth = closing.bracket_depth + 1
- for _opening_index, leaf in enumerate(leaves):
- if leaf is opening:
- break
-
- else:
- raise LookupError("Opening paren not found in `leaves`")
-
- commas = 0
- _opening_index += 1
- for leaf in leaves[_opening_index:]:
- if leaf is closing:
- break
-
- bracket_depth = leaf.bracket_depth
- if bracket_depth == depth and leaf.type == token.COMMA:
- commas += 1
- if leaf.parent and leaf.parent.type in {
- syms.arglist,
- syms.typedargslist,
- }:
- commas += 1
- break
-
- return commas < 2
-
-
-def get_features_used(node: Node) -> Set[Feature]:
- """Return a set of (relatively) new Python features used in this file.
-
- Currently looking for:
- - f-strings;
- - underscores in numeric literals;
- - trailing commas after * or ** in function signatures and calls;
- - positional only arguments in function signatures and lambdas;
- - assignment expression;
- - relaxed decorator syntax;
- """
- features: Set[Feature] = set()
- for n in node.pre_order():
- if n.type == token.STRING:
- value_head = n.value[:2] # type: ignore
- if value_head in {'f"', 'F"', "f'", "F'", "rf", "fr", "RF", "FR"}:
- features.add(Feature.F_STRINGS)
-
- elif n.type == token.NUMBER:
- if "_" in n.value: # type: ignore
- features.add(Feature.NUMERIC_UNDERSCORES)
-
- elif n.type == token.SLASH:
- if n.parent and n.parent.type in {syms.typedargslist, syms.arglist}:
- features.add(Feature.POS_ONLY_ARGUMENTS)
-
- elif n.type == token.COLONEQUAL:
- features.add(Feature.ASSIGNMENT_EXPRESSIONS)
-
- elif n.type == syms.decorator:
- if len(n.children) > 1 and not is_simple_decorator_expression(
- n.children[1]
- ):
- features.add(Feature.RELAXED_DECORATORS)
-
- elif (
- n.type in {syms.typedargslist, syms.arglist}
- and n.children
- and n.children[-1].type == token.COMMA
- ):
- if n.type == syms.typedargslist:
- feature = Feature.TRAILING_COMMA_IN_DEF
- else:
- feature = Feature.TRAILING_COMMA_IN_CALL
-
- for ch in n.children:
- if ch.type in STARS:
- features.add(feature)
-
- if ch.type == syms.argument:
- for argch in ch.children:
- if argch.type in STARS:
- features.add(feature)
-
- return features
-
-
-def detect_target_versions(node: Node) -> Set[TargetVersion]:
- """Detect the version to target based on the nodes used."""
- features = get_features_used(node)
- return {
- version for version in TargetVersion if features <= VERSION_TO_FEATURES[version]
- }
-
-
-def generate_trailers_to_omit(line: Line, line_length: int) -> Iterator[Set[LeafID]]:
- """Generate sets of closing bracket IDs that should be omitted in a RHS.
-
- Brackets can be omitted if the entire trailer up to and including
- a preceding closing bracket fits in one line.
-
- Yielded sets are cumulative (contain results of previous yields, too). First
- set is empty, unless the line should explode, in which case bracket pairs until
- the one that needs to explode are omitted.
- """
-
- omit: Set[LeafID] = set()
- if not line.magic_trailing_comma:
- yield omit
-
- length = 4 * line.depth
- opening_bracket: Optional[Leaf] = None
- closing_bracket: Optional[Leaf] = None
- inner_brackets: Set[LeafID] = set()
- for index, leaf, leaf_length in enumerate_with_length(line, reversed=True):
- length += leaf_length
- if length > line_length:
- break
-
- has_inline_comment = leaf_length > len(leaf.value) + len(leaf.prefix)
- if leaf.type == STANDALONE_COMMENT or has_inline_comment:
- break
-
- if opening_bracket:
- if leaf is opening_bracket:
- opening_bracket = None
- elif leaf.type in CLOSING_BRACKETS:
- prev = line.leaves[index - 1] if index > 0 else None
- if (
- prev
- and prev.type == token.COMMA
- and not is_one_tuple_between(
- leaf.opening_bracket, leaf, line.leaves
- )
- ):
- # Never omit bracket pairs with trailing commas.
- # We need to explode on those.
- break
-
- inner_brackets.add(id(leaf))
- elif leaf.type in CLOSING_BRACKETS:
- prev = line.leaves[index - 1] if index > 0 else None
- if prev and prev.type in OPENING_BRACKETS:
- # Empty brackets would fail a split so treat them as "inner"
- # brackets (e.g. only add them to the `omit` set if another
- # pair of brackets was good enough.
- inner_brackets.add(id(leaf))
- continue
-
- if closing_bracket:
- omit.add(id(closing_bracket))
- omit.update(inner_brackets)
- inner_brackets.clear()
- yield omit
-
- if (
- prev
- and prev.type == token.COMMA
- and not is_one_tuple_between(leaf.opening_bracket, leaf, line.leaves)
- ):
- # Never omit bracket pairs with trailing commas.
- # We need to explode on those.
- break
-
- if leaf.value:
- opening_bracket = leaf.opening_bracket
- closing_bracket = leaf
-
-
-def get_future_imports(node: Node) -> Set[str]:
- """Return a set of __future__ imports in the file."""
- imports: Set[str] = set()
-
- def get_imports_from_children(children: List[LN]) -> Generator[str, None, None]:
- for child in children:
- if isinstance(child, Leaf):
- if child.type == token.NAME:
- yield child.value
-
- elif child.type == syms.import_as_name:
- orig_name = child.children[0]
- assert isinstance(orig_name, Leaf), "Invalid syntax parsing imports"
- assert orig_name.type == token.NAME, "Invalid syntax parsing imports"
- yield orig_name.value
-
- elif child.type == syms.import_as_names:
- yield from get_imports_from_children(child.children)
-
- else:
- raise AssertionError("Invalid syntax parsing imports")
-
- for child in node.children:
- if child.type != syms.simple_stmt:
- break
-
- first_child = child.children[0]
- if isinstance(first_child, Leaf):
- # Continue looking if we see a docstring; otherwise stop.
- if (
- len(child.children) == 2
- and first_child.type == token.STRING
- and child.children[1].type == token.NEWLINE
- ):
- continue
-
- break
-
- elif first_child.type == syms.import_from:
- module_name = first_child.children[1]
- if not isinstance(module_name, Leaf) or module_name.value != "__future__":
- break
-
- imports |= set(get_imports_from_children(first_child.children[3:]))
- else:
- break
-
- return imports
-
-
-@lru_cache()
-def get_gitignore(root: Path) -> PathSpec:
- """Return a PathSpec matching gitignore content if present."""
- gitignore = root / ".gitignore"
- lines: List[str] = []
- if gitignore.is_file():
- with gitignore.open() as gf:
- lines = gf.readlines()
- return PathSpec.from_lines("gitwildmatch", lines)
-
-
-def normalize_path_maybe_ignore(
- path: Path, root: Path, report: "Report"
-) -> Optional[str]:
- """Normalize `path`. May return `None` if `path` was ignored.
-
- `report` is where "path ignored" output goes.
- """
- try:
- abspath = path if path.is_absolute() else Path.cwd() / path
- normalized_path = abspath.resolve().relative_to(root).as_posix()
- except OSError as e:
- report.path_ignored(path, f"cannot be read because {e}")
- return None
-
- except ValueError:
- if path.is_symlink():
- report.path_ignored(path, f"is a symbolic link that points outside {root}")
- return None
-
- raise
-
- return normalized_path
-
-
-def path_is_excluded(
- normalized_path: str,
- pattern: Optional[Pattern[str]],
-) -> bool:
- match = pattern.search(normalized_path) if pattern else None
- return bool(match and match.group(0))
-
-
-def gen_python_files(
- paths: Iterable[Path],
- root: Path,
- include: Pattern[str],
- exclude: Pattern[str],
- extend_exclude: Optional[Pattern[str]],
- force_exclude: Optional[Pattern[str]],
- report: "Report",
- gitignore: Optional[PathSpec],
-) -> Iterator[Path]:
- """Generate all files under `path` whose paths are not excluded by the
- `exclude_regex`, `extend_exclude`, or `force_exclude` regexes,
- but are included by the `include` regex.
-
- Symbolic links pointing outside of the `root` directory are ignored.
-
- `report` is where output about exclusions goes.
- """
- assert root.is_absolute(), f"INTERNAL ERROR: `root` must be absolute but is {root}"
- for child in paths:
- normalized_path = normalize_path_maybe_ignore(child, root, report)
- if normalized_path is None:
- continue
-
- # First ignore files matching .gitignore, if passed
- if gitignore is not None and gitignore.match_file(normalized_path):
- report.path_ignored(child, "matches the .gitignore file content")
- continue
-
- # Then ignore with `--exclude` `--extend-exclude` and `--force-exclude` options.
- normalized_path = "/" + normalized_path
- if child.is_dir():
- normalized_path += "/"
-
- if path_is_excluded(normalized_path, exclude):
- report.path_ignored(child, "matches the --exclude regular expression")
- continue
-
- if path_is_excluded(normalized_path, extend_exclude):
- report.path_ignored(
- child, "matches the --extend-exclude regular expression"
- )
- continue
-
- if path_is_excluded(normalized_path, force_exclude):
- report.path_ignored(child, "matches the --force-exclude regular expression")
- continue
-
- if child.is_dir():
- yield from gen_python_files(
- child.iterdir(),
- root,
- include,
- exclude,
- extend_exclude,
- force_exclude,
- report,
- gitignore,
- )
-
- elif child.is_file():
- include_match = include.search(normalized_path) if include else True
- if include_match:
- yield child
-
-
-@lru_cache()
-def find_project_root(srcs: Tuple[str, ...]) -> Path:
- """Return a directory containing .git, .hg, or pyproject.toml.
-
- That directory will be a common parent of all files and directories
- passed in `srcs`.
-
- If no directory in the tree contains a marker that would specify it's the
- project root, the root of the file system is returned.
- """
- if not srcs:
- return Path("/").resolve()
-
- path_srcs = [Path(Path.cwd(), src).resolve() for src in srcs]
-
- # A list of lists of parents for each 'src'. 'src' is included as a
- # "parent" of itself if it is a directory
- src_parents = [
- list(path.parents) + ([path] if path.is_dir() else []) for path in path_srcs
- ]
-
- common_base = max(
- set.intersection(*(set(parents) for parents in src_parents)),
- key=lambda path: path.parts,
- )
-
- for directory in (common_base, *common_base.parents):
- if (directory / ".git").exists():
- return directory
-
- if (directory / ".hg").is_dir():
- return directory
-
- if (directory / "pyproject.toml").is_file():
- return directory
-
- return directory
-
-
-@lru_cache()
-def find_user_pyproject_toml() -> Path:
- r"""Return the path to the top-level user configuration for black.
-
- This looks for ~\.black on Windows and ~/.config/black on Linux and other
- Unix systems.
- """
- if sys.platform == "win32":
- # Windows
- user_config_path = Path.home() / ".black"
- else:
- config_root = os.environ.get("XDG_CONFIG_HOME", "~/.config")
- user_config_path = Path(config_root).expanduser() / "black"
- return user_config_path.resolve()
-
-
-@dataclass
-class Report:
- """Provides a reformatting counter. Can be rendered with `str(report)`."""
-
- check: bool = False
- diff: bool = False
- quiet: bool = False
- verbose: bool = False
- change_count: int = 0
- same_count: int = 0
- failure_count: int = 0
-
- def done(self, src: Path, changed: Changed) -> None:
- """Increment the counter for successful reformatting. Write out a message."""
- if changed is Changed.YES:
- reformatted = "would reformat" if self.check or self.diff else "reformatted"
- if self.verbose or not self.quiet:
- out(f"{reformatted} {src}")
- self.change_count += 1
- else:
- if self.verbose:
- if changed is Changed.NO:
- msg = f"{src} already well formatted, good job."
- else:
- msg = f"{src} wasn't modified on disk since last run."
- out(msg, bold=False)
- self.same_count += 1
-
- def failed(self, src: Path, message: str) -> None:
- """Increment the counter for failed reformatting. Write out a message."""
- err(f"error: cannot format {src}: {message}")
- self.failure_count += 1
-
- def path_ignored(self, path: Path, message: str) -> None:
- if self.verbose:
- out(f"{path} ignored: {message}", bold=False)
-
- @property
- def return_code(self) -> int:
- """Return the exit code that the app should use.
-
- This considers the current state of changed files and failures:
- - if there were any failures, return 123;
- - if any files were changed and --check is being used, return 1;
- - otherwise return 0.
- """
- # According to http://tldp.org/LDP/abs/html/exitcodes.html starting with
- # 126 we have special return codes reserved by the shell.
- if self.failure_count:
- return 123
-
- elif self.change_count and self.check:
- return 1
-
- return 0
-
- def __str__(self) -> str:
- """Render a color report of the current state.
-
- Use `click.unstyle` to remove colors.
- """
- if self.check or self.diff:
- reformatted = "would be reformatted"
- unchanged = "would be left unchanged"
- failed = "would fail to reformat"
- else:
- reformatted = "reformatted"
- unchanged = "left unchanged"
- failed = "failed to reformat"
- report = []
- if self.change_count:
- s = "s" if self.change_count > 1 else ""
- report.append(
- click.style(f"{self.change_count} file{s} {reformatted}", bold=True)
- )
- if self.same_count:
- s = "s" if self.same_count > 1 else ""
- report.append(f"{self.same_count} file{s} {unchanged}")
- if self.failure_count:
- s = "s" if self.failure_count > 1 else ""
- report.append(
- click.style(f"{self.failure_count} file{s} {failed}", fg="red")
- )
- return ", ".join(report) + "."
-
-
-def parse_ast(src: str) -> Union[ast.AST, ast3.AST, ast27.AST]:
- filename = "<unknown>"
- if sys.version_info >= (3, 8):
- # TODO: support Python 4+ ;)
- for minor_version in range(sys.version_info[1], 4, -1):
- try:
- return ast.parse(src, filename, feature_version=(3, minor_version))
- except SyntaxError:
- continue
- else:
- for feature_version in (7, 6):
- try:
- return ast3.parse(src, filename, feature_version=feature_version)
- except SyntaxError:
- continue
- if ast27.__name__ == "ast":
- raise SyntaxError(
- "The requested source code has invalid Python 3 syntax.\n"
- "If you are trying to format Python 2 files please reinstall Black"
- " with the 'python2' extra: `python3 -m pip install black[python2]`."
- )
- return ast27.parse(src)
-
-
-def _fixup_ast_constants(
- node: Union[ast.AST, ast3.AST, ast27.AST]
-) -> Union[ast.AST, ast3.AST, ast27.AST]:
- """Map ast nodes deprecated in 3.8 to Constant."""
- if isinstance(node, (ast.Str, ast3.Str, ast27.Str, ast.Bytes, ast3.Bytes)):
- return ast.Constant(value=node.s)
-
- if isinstance(node, (ast.Num, ast3.Num, ast27.Num)):
- return ast.Constant(value=node.n)
-
- if isinstance(node, (ast.NameConstant, ast3.NameConstant)):
- return ast.Constant(value=node.value)
-
- return node
-
-
-def _stringify_ast(
- node: Union[ast.AST, ast3.AST, ast27.AST], depth: int = 0
-) -> Iterator[str]:
- """Simple visitor generating strings to compare ASTs by content."""
-
- node = _fixup_ast_constants(node)
-
- yield f"{' ' * depth}{node.__class__.__name__}("
-
- for field in sorted(node._fields): # noqa: F402
- # TypeIgnore has only one field 'lineno' which breaks this comparison
- type_ignore_classes = (ast3.TypeIgnore, ast27.TypeIgnore)
- if sys.version_info >= (3, 8):
- type_ignore_classes += (ast.TypeIgnore,)
- if isinstance(node, type_ignore_classes):
- break
-
- try:
- value = getattr(node, field)
- except AttributeError:
- continue
-
- yield f"{' ' * (depth+1)}{field}="
-
- if isinstance(value, list):
- for item in value:
- # Ignore nested tuples within del statements, because we may insert
- # parentheses and they change the AST.
- if (
- field == "targets"
- and isinstance(node, (ast.Delete, ast3.Delete, ast27.Delete))
- and isinstance(item, (ast.Tuple, ast3.Tuple, ast27.Tuple))
- ):
- for item in item.elts:
- yield from _stringify_ast(item, depth + 2)
-
- elif isinstance(item, (ast.AST, ast3.AST, ast27.AST)):
- yield from _stringify_ast(item, depth + 2)
-
- elif isinstance(value, (ast.AST, ast3.AST, ast27.AST)):
- yield from _stringify_ast(value, depth + 2)
-
- else:
- # Constant strings may be indented across newlines, if they are
- # docstrings; fold spaces after newlines when comparing. Similarly,
- # trailing and leading space may be removed.
- # Note that when formatting Python 2 code, at least with Windows
- # line-endings, docstrings can end up here as bytes instead of
- # str so make sure that we handle both cases.
- if (
- isinstance(node, ast.Constant)
- and field == "value"
- and isinstance(value, (str, bytes))
- ):
- lineend = "\n" if isinstance(value, str) else b"\n"
- # To normalize, we strip any leading and trailing space from
- # each line...
- stripped = [line.strip() for line in value.splitlines()]
- normalized = lineend.join(stripped) # type: ignore[attr-defined]
- # ...and remove any blank lines at the beginning and end of
- # the whole string
- normalized = normalized.strip()
- else:
- normalized = value
- yield f"{' ' * (depth+2)}{normalized!r}, # {value.__class__.__name__}"
-
- yield f"{' ' * depth}) # /{node.__class__.__name__}"
-
-
-def assert_equivalent(src: str, dst: str, *, pass_num: int = 1) -> None:
- """Raise AssertionError if `src` and `dst` aren't equivalent."""
- try:
- src_ast = parse_ast(src)
- except Exception as exc:
- raise AssertionError(
- "cannot use --safe with this file; failed to parse source file. AST"
- f" error message: {exc}"
- )
-
- try:
- dst_ast = parse_ast(dst)
- except Exception as exc:
- log = dump_to_file("".join(traceback.format_tb(exc.__traceback__)), dst)
- raise AssertionError(
- f"INTERNAL ERROR: Black produced invalid code on pass {pass_num}: {exc}. "
- "Please report a bug on https://github.com/psf/black/issues. "
- f"This invalid output might be helpful: {log}"
- ) from None
-
- src_ast_str = "\n".join(_stringify_ast(src_ast))
- dst_ast_str = "\n".join(_stringify_ast(dst_ast))
- if src_ast_str != dst_ast_str:
- log = dump_to_file(diff(src_ast_str, dst_ast_str, "src", "dst"))
- raise AssertionError(
- "INTERNAL ERROR: Black produced code that is not equivalent to the"
- f" source on pass {pass_num}. Please report a bug on "
- f"https://github.com/psf/black/issues. This diff might be helpful: {log}"
- ) from None
-
-
-def assert_stable(src: str, dst: str, mode: Mode) -> None:
- """Raise AssertionError if `dst` reformats differently the second time."""
- newdst = format_str(dst, mode=mode)
- if dst != newdst:
- log = dump_to_file(
- str(mode),
- diff(src, dst, "source", "first pass"),
- diff(dst, newdst, "first pass", "second pass"),
- )
- raise AssertionError(
- "INTERNAL ERROR: Black produced different code on the second pass of the"
- " formatter. Please report a bug on https://github.com/psf/black/issues."
- f" This diff might be helpful: {log}"
- ) from None
-
-
-@mypyc_attr(patchable=True)
-def dump_to_file(*output: str, ensure_final_newline: bool = True) -> str:
- """Dump `output` to a temporary file. Return path to the file."""
- with tempfile.NamedTemporaryFile(
- mode="w", prefix="blk_", suffix=".log", delete=False, encoding="utf8"
- ) as f:
- for lines in output:
- f.write(lines)
- if ensure_final_newline and lines and lines[-1] != "\n":
- f.write("\n")
- return f.name
-
-
-@contextmanager
-def nullcontext() -> Iterator[None]:
- """Return an empty context manager.
-
- To be used like `nullcontext` in Python 3.7.
- """
- yield
-
-
-def diff(a: str, b: str, a_name: str, b_name: str) -> str:
- """Return a unified diff string between strings `a` and `b`."""
- import difflib
-
- a_lines = [line for line in a.splitlines(keepends=True)]
- b_lines = [line for line in b.splitlines(keepends=True)]
- diff_lines = []
- for line in difflib.unified_diff(
- a_lines, b_lines, fromfile=a_name, tofile=b_name, n=5
- ):
- # Work around https://bugs.python.org/issue2142
- # See https://www.gnu.org/software/diffutils/manual/html_node/Incomplete-Lines.html
- if line[-1] == "\n":
- diff_lines.append(line)
- else:
- diff_lines.append(line + "\n")
- diff_lines.append("\\ No newline at end of file\n")
- return "".join(diff_lines)
-
-
-def cancel(tasks: Iterable["asyncio.Task[Any]"]) -> None:
- """asyncio signal handler that cancels all `tasks` and reports to stderr."""
- err("Aborted!")
- for task in tasks:
- task.cancel()
-
-
-def shutdown(loop: asyncio.AbstractEventLoop) -> None:
- """Cancel all pending tasks on `loop`, wait for them, and close the loop."""
- try:
- if sys.version_info[:2] >= (3, 7):
- all_tasks = asyncio.all_tasks
- else:
- all_tasks = asyncio.Task.all_tasks
- # This part is borrowed from asyncio/runners.py in Python 3.7b2.
- to_cancel = [task for task in all_tasks(loop) if not task.done()]
- if not to_cancel:
- return
-
- for task in to_cancel:
- task.cancel()
- loop.run_until_complete(
- asyncio.gather(*to_cancel, loop=loop, return_exceptions=True)
- )
- finally:
- # `concurrent.futures.Future` objects cannot be cancelled once they
- # are already running. There might be some when the `shutdown()` happened.
- # Silence their logger's spew about the event loop being closed.
- cf_logger = logging.getLogger("concurrent.futures")
- cf_logger.setLevel(logging.CRITICAL)
- loop.close()
-
-
-def sub_twice(regex: Pattern[str], replacement: str, original: str) -> str:
- """Replace `regex` with `replacement` twice on `original`.
-
- This is used by string normalization to perform replaces on
- overlapping matches.
- """
- return regex.sub(replacement, regex.sub(replacement, original))
-
-
-def re_compile_maybe_verbose(regex: str) -> Pattern[str]:
- """Compile a regular expression string in `regex`.
-
- If it contains newlines, use verbose mode.
- """
- if "\n" in regex:
- regex = "(?x)" + regex
- compiled: Pattern[str] = re.compile(regex)
- return compiled
-
-
-def enumerate_reversed(sequence: Sequence[T]) -> Iterator[Tuple[Index, T]]:
- """Like `reversed(enumerate(sequence))` if that were possible."""
- index = len(sequence) - 1
- for element in reversed(sequence):
- yield (index, element)
- index -= 1
-
-
-def enumerate_with_length(
- line: Line, reversed: bool = False
-) -> Iterator[Tuple[Index, Leaf, int]]:
- """Return an enumeration of leaves with their length.
-
- Stops prematurely on multiline strings and standalone comments.
- """
- op = cast(
- Callable[[Sequence[Leaf]], Iterator[Tuple[Index, Leaf]]],
- enumerate_reversed if reversed else enumerate,
- )
- for index, leaf in op(line.leaves):
- length = len(leaf.prefix) + len(leaf.value)
- if "\n" in leaf.value:
- return # Multiline strings, we can't continue.
-
- for comment in line.comments_after(leaf):
- length += len(comment.value)
-
- yield index, leaf, length
-
-
-def is_line_short_enough(line: Line, *, line_length: int, line_str: str = "") -> bool:
- """Return True if `line` is no longer than `line_length`.
-
- Uses the provided `line_str` rendering, if any, otherwise computes a new one.
- """
- if not line_str:
- line_str = line_to_string(line)
- return (
- len(line_str) <= line_length
- and "\n" not in line_str # multiline strings
- and not line.contains_standalone_comments()
- )
-
-
-def can_be_split(line: Line) -> bool:
- """Return False if the line cannot be split *for sure*.
-
- This is not an exhaustive search but a cheap heuristic that we can use to
- avoid some unfortunate formattings (mostly around wrapping unsplittable code
- in unnecessary parentheses).
- """
- leaves = line.leaves
- if len(leaves) < 2:
- return False
-
- if leaves[0].type == token.STRING and leaves[1].type == token.DOT:
- call_count = 0
- dot_count = 0
- next = leaves[-1]
- for leaf in leaves[-2::-1]:
- if leaf.type in OPENING_BRACKETS:
- if next.type not in CLOSING_BRACKETS:
- return False
-
- call_count += 1
- elif leaf.type == token.DOT:
- dot_count += 1
- elif leaf.type == token.NAME:
- if not (next.type == token.DOT or next.type in OPENING_BRACKETS):
- return False
-
- elif leaf.type not in CLOSING_BRACKETS:
- return False
-
- if dot_count > 1 and call_count > 1:
- return False
-
- return True
-
-
-def can_omit_invisible_parens(
- line: Line,
- line_length: int,
- omit_on_explode: Collection[LeafID] = (),
-) -> bool:
- """Does `line` have a shape safe to reformat without optional parens around it?
-
- Returns True for only a subset of potentially nice looking formattings but
- the point is to not return false positives that end up producing lines that
- are too long.
- """
- bt = line.bracket_tracker
- if not bt.delimiters:
- # Without delimiters the optional parentheses are useless.
- return True
-
- max_priority = bt.max_delimiter_priority()
- if bt.delimiter_count_with_priority(max_priority) > 1:
- # With more than one delimiter of a kind the optional parentheses read better.
- return False
-
- if max_priority == DOT_PRIORITY:
- # A single stranded method call doesn't require optional parentheses.
- return True
-
- assert len(line.leaves) >= 2, "Stranded delimiter"
-
- # With a single delimiter, omit if the expression starts or ends with
- # a bracket.
- first = line.leaves[0]
- second = line.leaves[1]
- if first.type in OPENING_BRACKETS and second.type not in CLOSING_BRACKETS:
- if _can_omit_opening_paren(line, first=first, line_length=line_length):
- return True
-
- # Note: we are not returning False here because a line might have *both*
- # a leading opening bracket and a trailing closing bracket. If the
- # opening bracket doesn't match our rule, maybe the closing will.
-
- penultimate = line.leaves[-2]
- last = line.leaves[-1]
- if line.magic_trailing_comma:
- try:
- penultimate, last = last_two_except(line.leaves, omit=omit_on_explode)
- except LookupError:
- # Turns out we'd omit everything. We cannot skip the optional parentheses.
- return False
-
- if (
- last.type == token.RPAR
- or last.type == token.RBRACE
- or (
- # don't use indexing for omitting optional parentheses;
- # it looks weird
- last.type == token.RSQB
- and last.parent
- and last.parent.type != syms.trailer
- )
- ):
- if penultimate.type in OPENING_BRACKETS:
- # Empty brackets don't help.
- return False
-
- if is_multiline_string(first):
- # Additional wrapping of a multiline string in this situation is
- # unnecessary.
- return True
-
- if line.magic_trailing_comma and penultimate.type == token.COMMA:
- # The rightmost non-omitted bracket pair is the one we want to explode on.
- return True
-
- if _can_omit_closing_paren(line, last=last, line_length=line_length):
- return True
-
- return False
-
-
-def _can_omit_opening_paren(line: Line, *, first: Leaf, line_length: int) -> bool:
- """See `can_omit_invisible_parens`."""
- remainder = False
- length = 4 * line.depth
- _index = -1
- for _index, leaf, leaf_length in enumerate_with_length(line):
- if leaf.type in CLOSING_BRACKETS and leaf.opening_bracket is first:
- remainder = True
- if remainder:
- length += leaf_length
- if length > line_length:
- break
-
- if leaf.type in OPENING_BRACKETS:
- # There are brackets we can further split on.
- remainder = False
-
- else:
- # checked the entire string and line length wasn't exceeded
- if len(line.leaves) == _index + 1:
- return True
-
- return False
-
-
-def _can_omit_closing_paren(line: Line, *, last: Leaf, line_length: int) -> bool:
- """See `can_omit_invisible_parens`."""
- length = 4 * line.depth
- seen_other_brackets = False
- for _index, leaf, leaf_length in enumerate_with_length(line):
- length += leaf_length
- if leaf is last.opening_bracket:
- if seen_other_brackets or length <= line_length:
- return True
-
- elif leaf.type in OPENING_BRACKETS:
- # There are brackets we can further split on.
- seen_other_brackets = True
-
- return False
-
-
-def last_two_except(leaves: List[Leaf], omit: Collection[LeafID]) -> Tuple[Leaf, Leaf]:
- """Return (penultimate, last) leaves skipping brackets in `omit` and contents."""
- stop_after = None
- last = None
- for leaf in reversed(leaves):
- if stop_after:
- if leaf is stop_after:
- stop_after = None
- continue
-
- if last:
- return leaf, last
-
- if id(leaf) in omit:
- stop_after = leaf.opening_bracket
- else:
- last = leaf
- else:
- raise LookupError("Last two leaves were also skipped")
-
-
-def run_transformer(
- line: Line,
- transform: Transformer,
- mode: Mode,
- features: Collection[Feature],
- *,
- line_str: str = "",
-) -> List[Line]:
- if not line_str:
- line_str = line_to_string(line)
- result: List[Line] = []
- for transformed_line in transform(line, features):
- if str(transformed_line).strip("\n") == line_str:
- raise CannotTransform("Line transformer returned an unchanged result")
-
- result.extend(transform_line(transformed_line, mode=mode, features=features))
-
- if not (
- transform.__name__ == "rhs"
- and line.bracket_tracker.invisible
- and not any(bracket.value for bracket in line.bracket_tracker.invisible)
- and not line.contains_multiline_strings()
- and not result[0].contains_uncollapsable_type_comments()
- and not result[0].contains_unsplittable_type_ignore()
- and not is_line_short_enough(result[0], line_length=mode.line_length)
- ):
- return result
-
- line_copy = line.clone()
- append_leaves(line_copy, line, line.leaves)
- features_fop = set(features) | {Feature.FORCE_OPTIONAL_PARENTHESES}
- second_opinion = run_transformer(
- line_copy, transform, mode, features_fop, line_str=line_str
- )
- if all(
- is_line_short_enough(ln, line_length=mode.line_length) for ln in second_opinion
- ):
- result = second_opinion
- return result
-
-
-def get_cache_file(mode: Mode) -> Path:
- return CACHE_DIR / f"cache.{mode.get_cache_key()}.pickle"
-
-
-def read_cache(mode: Mode) -> Cache:
- """Read the cache if it exists and is well formed.
-
- If it is not well formed, the call to write_cache later should resolve the issue.
- """
- cache_file = get_cache_file(mode)
- if not cache_file.exists():
- return {}
-
- with cache_file.open("rb") as fobj:
- try:
- cache: Cache = pickle.load(fobj)
- except (pickle.UnpicklingError, ValueError):
- return {}
-
- return cache
-
-
-def get_cache_info(path: Path) -> CacheInfo:
- """Return the information used to check if a file is already formatted or not."""
- stat = path.stat()
- return stat.st_mtime, stat.st_size
-
-
-def filter_cached(cache: Cache, sources: Iterable[Path]) -> Tuple[Set[Path], Set[Path]]:
- """Split an iterable of paths in `sources` into two sets.
-
- The first contains paths of files that modified on disk or are not in the
- cache. The other contains paths to non-modified files.
- """
- todo, done = set(), set()
- for src in sources:
- res_src = src.resolve()
- if cache.get(str(res_src)) != get_cache_info(res_src):
- todo.add(src)
- else:
- done.add(src)
- return todo, done
-
-
-def write_cache(cache: Cache, sources: Iterable[Path], mode: Mode) -> None:
- """Update the cache file."""
- cache_file = get_cache_file(mode)
- try:
- CACHE_DIR.mkdir(parents=True, exist_ok=True)
- new_cache = {
- **cache,
- **{str(src.resolve()): get_cache_info(src) for src in sources},
- }
- with tempfile.NamedTemporaryFile(dir=str(cache_file.parent), delete=False) as f:
- pickle.dump(new_cache, f, protocol=4)
- os.replace(f.name, cache_file)
- except OSError:
- pass
-
-
-def patch_click() -> None:
- """Make Click not crash.
-
- On certain misconfigured environments, Python 3 selects the ASCII encoding as the
- default which restricts paths that it can access during the lifetime of the
- application. Click refuses to work in this scenario by raising a RuntimeError.
-
- In case of Black the likelihood that non-ASCII characters are going to be used in
- file paths is minimal since it's Python source code. Moreover, this crash was
- spurious on Python 3.7 thanks to PEP 538 and PEP 540.
- """
- try:
- from click import core
- from click import _unicodefun # type: ignore
- except ModuleNotFoundError:
- return
-
- for module in (core, _unicodefun):
- if hasattr(module, "_verify_python3_env"):
- module._verify_python3_env = lambda: None
+ for module in (core, _unicodefun):
+ if hasattr(module, "_verify_python3_env"):
+ module._verify_python3_env = lambda: None
def patched_main() -> None:
@@ -7025,66 +1056,5 @@ def patched_main() -> None:
main()
-def is_docstring(leaf: Leaf) -> bool:
- if prev_siblings_are(
- leaf.parent, [None, token.NEWLINE, token.INDENT, syms.simple_stmt]
- ):
- return True
-
- # Multiline docstring on the same line as the `def`.
- if prev_siblings_are(leaf.parent, [syms.parameters, token.COLON, syms.simple_stmt]):
- # `syms.parameters` is only used in funcdefs and async_funcdefs in the Python
- # grammar. We're safe to return True without further checks.
- return True
-
- return False
-
-
-def lines_with_leading_tabs_expanded(s: str) -> List[str]:
- """
- Splits string into lines and expands only leading tabs (following the normal
- Python rules)
- """
- lines = []
- for line in s.splitlines():
- # Find the index of the first non-whitespace character after a string of
- # whitespace that includes at least one tab
- match = re.match(r"\s*\t+\s*(\S)", line)
- if match:
- first_non_whitespace_idx = match.start(1)
-
- lines.append(
- line[:first_non_whitespace_idx].expandtabs()
- + line[first_non_whitespace_idx:]
- )
- else:
- lines.append(line)
- return lines
-
-
-def fix_docstring(docstring: str, prefix: str) -> str:
- # https://www.python.org/dev/peps/pep-0257/#handling-docstring-indentation
- if not docstring:
- return ""
- lines = lines_with_leading_tabs_expanded(docstring)
- # Determine minimum indentation (first line doesn't count):
- indent = sys.maxsize
- for line in lines[1:]:
- stripped = line.lstrip()
- if stripped:
- indent = min(indent, len(line) - len(stripped))
- # Remove indentation (first line is special):
- trimmed = [lines[0].strip()]
- if indent < sys.maxsize:
- last_line_idx = len(lines) - 2
- for i, line in enumerate(lines[1:]):
- stripped_line = line[indent:].rstrip()
- if stripped_line or i == last_line_idx:
- trimmed.append(prefix + stripped_line)
- else:
- trimmed.append("")
- return "\n".join(trimmed)
-
-
if __name__ == "__main__":
patched_main()
diff --git a/src/black/brackets.py b/src/black/brackets.py
new file mode 100644
index 0000000..bb865a0
--- /dev/null
+++ b/src/black/brackets.py
@@ -0,0 +1,334 @@
+"""Builds on top of nodes.py to track brackets."""
+
+from dataclasses import dataclass, field
+import sys
+from typing import Dict, Iterable, List, Optional, Tuple, Union
+
+if sys.version_info < (3, 8):
+ from typing_extensions import Final
+else:
+ from typing import Final
+
+from blib2to3.pytree import Leaf, Node
+from blib2to3.pgen2 import token
+
+from black.nodes import syms, is_vararg, VARARGS_PARENTS, UNPACKING_PARENTS
+from black.nodes import BRACKET, OPENING_BRACKETS, CLOSING_BRACKETS
+from black.nodes import MATH_OPERATORS, COMPARATORS, LOGIC_OPERATORS
+
+# types
+LN = Union[Leaf, Node]
+Depth = int
+LeafID = int
+NodeType = int
+Priority = int
+
+
+COMPREHENSION_PRIORITY: Final = 20
+COMMA_PRIORITY: Final = 18
+TERNARY_PRIORITY: Final = 16
+LOGIC_PRIORITY: Final = 14
+STRING_PRIORITY: Final = 12
+COMPARATOR_PRIORITY: Final = 10
+MATH_PRIORITIES: Final = {
+ token.VBAR: 9,
+ token.CIRCUMFLEX: 8,
+ token.AMPER: 7,
+ token.LEFTSHIFT: 6,
+ token.RIGHTSHIFT: 6,
+ token.PLUS: 5,
+ token.MINUS: 5,
+ token.STAR: 4,
+ token.SLASH: 4,
+ token.DOUBLESLASH: 4,
+ token.PERCENT: 4,
+ token.AT: 4,
+ token.TILDE: 3,
+ token.DOUBLESTAR: 2,
+}
+DOT_PRIORITY: Final = 1
+
+
+class BracketMatchError(KeyError):
+ """Raised when an opening bracket is unable to be matched to a closing bracket."""
+
+
+@dataclass
+class BracketTracker:
+ """Keeps track of brackets on a line."""
+
+ depth: int = 0
+ bracket_match: Dict[Tuple[Depth, NodeType], Leaf] = field(default_factory=dict)
+ delimiters: Dict[LeafID, Priority] = field(default_factory=dict)
+ previous: Optional[Leaf] = None
+ _for_loop_depths: List[int] = field(default_factory=list)
+ _lambda_argument_depths: List[int] = field(default_factory=list)
+ invisible: List[Leaf] = field(default_factory=list)
+
+ def mark(self, leaf: Leaf) -> None:
+ """Mark `leaf` with bracket-related metadata. Keep track of delimiters.
+
+ All leaves receive an int `bracket_depth` field that stores how deep
+ within brackets a given leaf is. 0 means there are no enclosing brackets
+ that started on this line.
+
+ If a leaf is itself a closing bracket, it receives an `opening_bracket`
+ field that it forms a pair with. This is a one-directional link to
+ avoid reference cycles.
+
+ If a leaf is a delimiter (a token on which Black can split the line if
+ needed) and it's on depth 0, its `id()` is stored in the tracker's
+ `delimiters` field.
+ """
+ if leaf.type == token.COMMENT:
+ return
+
+ self.maybe_decrement_after_for_loop_variable(leaf)
+ self.maybe_decrement_after_lambda_arguments(leaf)
+ if leaf.type in CLOSING_BRACKETS:
+ self.depth -= 1
+ try:
+ opening_bracket = self.bracket_match.pop((self.depth, leaf.type))
+ except KeyError as e:
+ raise BracketMatchError(
+ "Unable to match a closing bracket to the following opening"
+ f" bracket: {leaf}"
+ ) from e
+ leaf.opening_bracket = opening_bracket
+ if not leaf.value:
+ self.invisible.append(leaf)
+ leaf.bracket_depth = self.depth
+ if self.depth == 0:
+ delim = is_split_before_delimiter(leaf, self.previous)
+ if delim and self.previous is not None:
+ self.delimiters[id(self.previous)] = delim
+ else:
+ delim = is_split_after_delimiter(leaf, self.previous)
+ if delim:
+ self.delimiters[id(leaf)] = delim
+ if leaf.type in OPENING_BRACKETS:
+ self.bracket_match[self.depth, BRACKET[leaf.type]] = leaf
+ self.depth += 1
+ if not leaf.value:
+ self.invisible.append(leaf)
+ self.previous = leaf
+ self.maybe_increment_lambda_arguments(leaf)
+ self.maybe_increment_for_loop_variable(leaf)
+
+ def any_open_brackets(self) -> bool:
+ """Return True if there is an yet unmatched open bracket on the line."""
+ return bool(self.bracket_match)
+
+ def max_delimiter_priority(self, exclude: Iterable[LeafID] = ()) -> Priority:
+ """Return the highest priority of a delimiter found on the line.
+
+ Values are consistent with what `is_split_*_delimiter()` return.
+ Raises ValueError on no delimiters.
+ """
+ return max(v for k, v in self.delimiters.items() if k not in exclude)
+
+ def delimiter_count_with_priority(self, priority: Priority = 0) -> int:
+ """Return the number of delimiters with the given `priority`.
+
+ If no `priority` is passed, defaults to max priority on the line.
+ """
+ if not self.delimiters:
+ return 0
+
+ priority = priority or self.max_delimiter_priority()
+ return sum(1 for p in self.delimiters.values() if p == priority)
+
+ def maybe_increment_for_loop_variable(self, leaf: Leaf) -> bool:
+ """In a for loop, or comprehension, the variables are often unpacks.
+
+ To avoid splitting on the comma in this situation, increase the depth of
+ tokens between `for` and `in`.
+ """
+ if leaf.type == token.NAME and leaf.value == "for":
+ self.depth += 1
+ self._for_loop_depths.append(self.depth)
+ return True
+
+ return False
+
+ def maybe_decrement_after_for_loop_variable(self, leaf: Leaf) -> bool:
+ """See `maybe_increment_for_loop_variable` above for explanation."""
+ if (
+ self._for_loop_depths
+ and self._for_loop_depths[-1] == self.depth
+ and leaf.type == token.NAME
+ and leaf.value == "in"
+ ):
+ self.depth -= 1
+ self._for_loop_depths.pop()
+ return True
+
+ return False
+
+ def maybe_increment_lambda_arguments(self, leaf: Leaf) -> bool:
+ """In a lambda expression, there might be more than one argument.
+
+ To avoid splitting on the comma in this situation, increase the depth of
+ tokens between `lambda` and `:`.
+ """
+ if leaf.type == token.NAME and leaf.value == "lambda":
+ self.depth += 1
+ self._lambda_argument_depths.append(self.depth)
+ return True
+
+ return False
+
+ def maybe_decrement_after_lambda_arguments(self, leaf: Leaf) -> bool:
+ """See `maybe_increment_lambda_arguments` above for explanation."""
+ if (
+ self._lambda_argument_depths
+ and self._lambda_argument_depths[-1] == self.depth
+ and leaf.type == token.COLON
+ ):
+ self.depth -= 1
+ self._lambda_argument_depths.pop()
+ return True
+
+ return False
+
+ def get_open_lsqb(self) -> Optional[Leaf]:
+ """Return the most recent opening square bracket (if any)."""
+ return self.bracket_match.get((self.depth - 1, token.RSQB))
+
+
+def is_split_after_delimiter(leaf: Leaf, previous: Optional[Leaf] = None) -> Priority:
+ """Return the priority of the `leaf` delimiter, given a line break after it.
+
+ The delimiter priorities returned here are from those delimiters that would
+ cause a line break after themselves.
+
+ Higher numbers are higher priority.
+ """
+ if leaf.type == token.COMMA:
+ return COMMA_PRIORITY
+
+ return 0
+
+
+def is_split_before_delimiter(leaf: Leaf, previous: Optional[Leaf] = None) -> Priority:
+ """Return the priority of the `leaf` delimiter, given a line break before it.
+
+ The delimiter priorities returned here are from those delimiters that would
+ cause a line break before themselves.
+
+ Higher numbers are higher priority.
+ """
+ if is_vararg(leaf, within=VARARGS_PARENTS | UNPACKING_PARENTS):
+ # * and ** might also be MATH_OPERATORS but in this case they are not.
+ # Don't treat them as a delimiter.
+ return 0
+
+ if (
+ leaf.type == token.DOT
+ and leaf.parent
+ and leaf.parent.type not in {syms.import_from, syms.dotted_name}
+ and (previous is None or previous.type in CLOSING_BRACKETS)
+ ):
+ return DOT_PRIORITY
+
+ if (
+ leaf.type in MATH_OPERATORS
+ and leaf.parent
+ and leaf.parent.type not in {syms.factor, syms.star_expr}
+ ):
+ return MATH_PRIORITIES[leaf.type]
+
+ if leaf.type in COMPARATORS:
+ return COMPARATOR_PRIORITY
+
+ if (
+ leaf.type == token.STRING
+ and previous is not None
+ and previous.type == token.STRING
+ ):
+ return STRING_PRIORITY
+
+ if leaf.type not in {token.NAME, token.ASYNC}:
+ return 0
+
+ if (
+ leaf.value == "for"
+ and leaf.parent
+ and leaf.parent.type in {syms.comp_for, syms.old_comp_for}
+ or leaf.type == token.ASYNC
+ ):
+ if (
+ not isinstance(leaf.prev_sibling, Leaf)
+ or leaf.prev_sibling.value != "async"
+ ):
+ return COMPREHENSION_PRIORITY
+
+ if (
+ leaf.value == "if"
+ and leaf.parent
+ and leaf.parent.type in {syms.comp_if, syms.old_comp_if}
+ ):
+ return COMPREHENSION_PRIORITY
+
+ if leaf.value in {"if", "else"} and leaf.parent and leaf.parent.type == syms.test:
+ return TERNARY_PRIORITY
+
+ if leaf.value == "is":
+ return COMPARATOR_PRIORITY
+
+ if (
+ leaf.value == "in"
+ and leaf.parent
+ and leaf.parent.type in {syms.comp_op, syms.comparison}
+ and not (
+ previous is not None
+ and previous.type == token.NAME
+ and previous.value == "not"
+ )
+ ):
+ return COMPARATOR_PRIORITY
+
+ if (
+ leaf.value == "not"
+ and leaf.parent
+ and leaf.parent.type == syms.comp_op
+ and not (
+ previous is not None
+ and previous.type == token.NAME
+ and previous.value == "is"
+ )
+ ):
+ return COMPARATOR_PRIORITY
+
+ if leaf.value in LOGIC_OPERATORS and leaf.parent:
+ return LOGIC_PRIORITY
+
+ return 0
+
+
+def max_delimiter_priority_in_atom(node: LN) -> Priority:
+ """Return maximum delimiter priority inside `node`.
+
+ This is specific to atoms with contents contained in a pair of parentheses.
+ If `node` isn't an atom or there are no enclosing parentheses, returns 0.
+ """
+ if node.type != syms.atom:
+ return 0
+
+ first = node.children[0]
+ last = node.children[-1]
+ if not (first.type == token.LPAR and last.type == token.RPAR):
+ return 0
+
+ bt = BracketTracker()
+ for c in node.children[1:-1]:
+ if isinstance(c, Leaf):
+ bt.mark(c)
+ else:
+ for leaf in c.leaves():
+ bt.mark(leaf)
+ try:
+ return bt.max_delimiter_priority()
+
+ except ValueError:
+ return 0
diff --git a/src/black/cache.py b/src/black/cache.py
new file mode 100644
index 0000000..017a2a9
--- /dev/null
+++ b/src/black/cache.py
@@ -0,0 +1,83 @@
+"""Caching of formatted files with feature-based invalidation."""
+
+import os
+import pickle
+from pathlib import Path
+import tempfile
+from typing import Dict, Iterable, Set, Tuple
+
+from appdirs import user_cache_dir
+
+from black.mode import Mode
+
+from _black_version import version as __version__
+
+
+# types
+Timestamp = float
+FileSize = int
+CacheInfo = Tuple[Timestamp, FileSize]
+Cache = Dict[str, CacheInfo]
+
+
+CACHE_DIR = Path(user_cache_dir("black", version=__version__))
+
+
+def read_cache(mode: Mode) -> Cache:
+ """Read the cache if it exists and is well formed.
+
+ If it is not well formed, the call to write_cache later should resolve the issue.
+ """
+ cache_file = get_cache_file(mode)
+ if not cache_file.exists():
+ return {}
+
+ with cache_file.open("rb") as fobj:
+ try:
+ cache: Cache = pickle.load(fobj)
+ except (pickle.UnpicklingError, ValueError):
+ return {}
+
+ return cache
+
+
+def get_cache_file(mode: Mode) -> Path:
+ return CACHE_DIR / f"cache.{mode.get_cache_key()}.pickle"
+
+
+def get_cache_info(path: Path) -> CacheInfo:
+ """Return the information used to check if a file is already formatted or not."""
+ stat = path.stat()
+ return stat.st_mtime, stat.st_size
+
+
+def filter_cached(cache: Cache, sources: Iterable[Path]) -> Tuple[Set[Path], Set[Path]]:
+ """Split an iterable of paths in `sources` into two sets.
+
+ The first contains paths of files that modified on disk or are not in the
+ cache. The other contains paths to non-modified files.
+ """
+ todo, done = set(), set()
+ for src in sources:
+ res_src = src.resolve()
+ if cache.get(str(res_src)) != get_cache_info(res_src):
+ todo.add(src)
+ else:
+ done.add(src)
+ return todo, done
+
+
+def write_cache(cache: Cache, sources: Iterable[Path], mode: Mode) -> None:
+ """Update the cache file."""
+ cache_file = get_cache_file(mode)
+ try:
+ CACHE_DIR.mkdir(parents=True, exist_ok=True)
+ new_cache = {
+ **cache,
+ **{str(src.resolve()): get_cache_info(src) for src in sources},
+ }
+ with tempfile.NamedTemporaryFile(dir=str(cache_file.parent), delete=False) as f:
+ pickle.dump(new_cache, f, protocol=4)
+ os.replace(f.name, cache_file)
+ except OSError:
+ pass
diff --git a/src/black/comments.py b/src/black/comments.py
new file mode 100644
index 0000000..415e391
--- /dev/null
+++ b/src/black/comments.py
@@ -0,0 +1,269 @@
+from dataclasses import dataclass
+from functools import lru_cache
+import regex as re
+from typing import Iterator, List, Optional, Union
+
+from blib2to3.pytree import Node, Leaf
+from blib2to3.pgen2 import token
+
+from black.nodes import first_leaf_column, preceding_leaf, container_of
+from black.nodes import STANDALONE_COMMENT, WHITESPACE
+
+# types
+LN = Union[Leaf, Node]
+
+
+FMT_OFF = {"# fmt: off", "# fmt:off", "# yapf: disable"}
+FMT_SKIP = {"# fmt: skip", "# fmt:skip"}
+FMT_PASS = {*FMT_OFF, *FMT_SKIP}
+FMT_ON = {"# fmt: on", "# fmt:on", "# yapf: enable"}
+
+
+@dataclass
+class ProtoComment:
+ """Describes a piece of syntax that is a comment.
+
+ It's not a :class:`blib2to3.pytree.Leaf` so that:
+
+ * it can be cached (`Leaf` objects should not be reused more than once as
+ they store their lineno, column, prefix, and parent information);
+ * `newlines` and `consumed` fields are kept separate from the `value`. This
+ simplifies handling of special marker comments like ``# fmt: off/on``.
+ """
+
+ type: int # token.COMMENT or STANDALONE_COMMENT
+ value: str # content of the comment
+ newlines: int # how many newlines before the comment
+ consumed: int # how many characters of the original leaf's prefix did we consume
+
+
+def generate_comments(leaf: LN) -> Iterator[Leaf]:
+ """Clean the prefix of the `leaf` and generate comments from it, if any.
+
+ Comments in lib2to3 are shoved into the whitespace prefix. This happens
+ in `pgen2/driver.py:Driver.parse_tokens()`. This was a brilliant implementation
+ move because it does away with modifying the grammar to include all the
+ possible places in which comments can be placed.
+
+ The sad consequence for us though is that comments don't "belong" anywhere.
+ This is why this function generates simple parentless Leaf objects for
+ comments. We simply don't know what the correct parent should be.
+
+ No matter though, we can live without this. We really only need to
+ differentiate between inline and standalone comments. The latter don't
+ share the line with any code.
+
+ Inline comments are emitted as regular token.COMMENT leaves. Standalone
+ are emitted with a fake STANDALONE_COMMENT token identifier.
+ """
+ for pc in list_comments(leaf.prefix, is_endmarker=leaf.type == token.ENDMARKER):
+ yield Leaf(pc.type, pc.value, prefix="\n" * pc.newlines)
+
+
+@lru_cache(maxsize=4096)
+def list_comments(prefix: str, *, is_endmarker: bool) -> List[ProtoComment]:
+ """Return a list of :class:`ProtoComment` objects parsed from the given `prefix`."""
+ result: List[ProtoComment] = []
+ if not prefix or "#" not in prefix:
+ return result
+
+ consumed = 0
+ nlines = 0
+ ignored_lines = 0
+ for index, line in enumerate(re.split("\r?\n", prefix)):
+ consumed += len(line) + 1 # adding the length of the split '\n'
+ line = line.lstrip()
+ if not line:
+ nlines += 1
+ if not line.startswith("#"):
+ # Escaped newlines outside of a comment are not really newlines at
+ # all. We treat a single-line comment following an escaped newline
+ # as a simple trailing comment.
+ if line.endswith("\\"):
+ ignored_lines += 1
+ continue
+
+ if index == ignored_lines and not is_endmarker:
+ comment_type = token.COMMENT # simple trailing comment
+ else:
+ comment_type = STANDALONE_COMMENT
+ comment = make_comment(line)
+ result.append(
+ ProtoComment(
+ type=comment_type, value=comment, newlines=nlines, consumed=consumed
+ )
+ )
+ nlines = 0
+ return result
+
+
+def make_comment(content: str) -> str:
+ """Return a consistently formatted comment from the given `content` string.
+
+ All comments (except for "##", "#!", "#:", '#'", "#%%") should have a single
+ space between the hash sign and the content.
+
+ If `content` didn't start with a hash sign, one is provided.
+ """
+ content = content.rstrip()
+ if not content:
+ return "#"
+
+ if content[0] == "#":
+ content = content[1:]
+ NON_BREAKING_SPACE = "Â "
+ if (
+ content
+ and content[0] == NON_BREAKING_SPACE
+ and not content.lstrip().startswith("type:")
+ ):
+ content = " " + content[1:] # Replace NBSP by a simple space
+ if content and content[0] not in " !:#'%":
+ content = " " + content
+ return "#" + content
+
+
+def normalize_fmt_off(node: Node) -> None:
+ """Convert content between `# fmt: off`/`# fmt: on` into standalone comments."""
+ try_again = True
+ while try_again:
+ try_again = convert_one_fmt_off_pair(node)
+
+
+def convert_one_fmt_off_pair(node: Node) -> bool:
+ """Convert content of a single `# fmt: off`/`# fmt: on` into a standalone comment.
+
+ Returns True if a pair was converted.
+ """
+ for leaf in node.leaves():
+ previous_consumed = 0
+ for comment in list_comments(leaf.prefix, is_endmarker=False):
+ if comment.value not in FMT_PASS:
+ previous_consumed = comment.consumed
+ continue
+ # We only want standalone comments. If there's no previous leaf or
+ # the previous leaf is indentation, it's a standalone comment in
+ # disguise.
+ if comment.value in FMT_PASS and comment.type != STANDALONE_COMMENT:
+ prev = preceding_leaf(leaf)
+ if prev:
+ if comment.value in FMT_OFF and prev.type not in WHITESPACE:
+ continue
+ if comment.value in FMT_SKIP and prev.type in WHITESPACE:
+ continue
+
+ ignored_nodes = list(generate_ignored_nodes(leaf, comment))
+ if not ignored_nodes:
+ continue
+
+ first = ignored_nodes[0] # Can be a container node with the `leaf`.
+ parent = first.parent
+ prefix = first.prefix
+ first.prefix = prefix[comment.consumed :]
+ hidden_value = "".join(str(n) for n in ignored_nodes)
+ if comment.value in FMT_OFF:
+ hidden_value = comment.value + "\n" + hidden_value
+ if comment.value in FMT_SKIP:
+ hidden_value += " " + comment.value
+ if hidden_value.endswith("\n"):
+ # That happens when one of the `ignored_nodes` ended with a NEWLINE
+ # leaf (possibly followed by a DEDENT).
+ hidden_value = hidden_value[:-1]
+ first_idx: Optional[int] = None
+ for ignored in ignored_nodes:
+ index = ignored.remove()
+ if first_idx is None:
+ first_idx = index
+ assert parent is not None, "INTERNAL ERROR: fmt: on/off handling (1)"
+ assert first_idx is not None, "INTERNAL ERROR: fmt: on/off handling (2)"
+ parent.insert_child(
+ first_idx,
+ Leaf(
+ STANDALONE_COMMENT,
+ hidden_value,
+ prefix=prefix[:previous_consumed] + "\n" * comment.newlines,
+ ),
+ )
+ return True
+
+ return False
+
+
+def generate_ignored_nodes(leaf: Leaf, comment: ProtoComment) -> Iterator[LN]:
+ """Starting from the container of `leaf`, generate all leaves until `# fmt: on`.
+
+ If comment is skip, returns leaf only.
+ Stops at the end of the block.
+ """
+ container: Optional[LN] = container_of(leaf)
+ if comment.value in FMT_SKIP:
+ prev_sibling = leaf.prev_sibling
+ if comment.value in leaf.prefix and prev_sibling is not None:
+ leaf.prefix = leaf.prefix.replace(comment.value, "")
+ siblings = [prev_sibling]
+ while (
+ "\n" not in prev_sibling.prefix
+ and prev_sibling.prev_sibling is not None
+ ):
+ prev_sibling = prev_sibling.prev_sibling
+ siblings.insert(0, prev_sibling)
+ for sibling in siblings:
+ yield sibling
+ elif leaf.parent is not None:
+ yield leaf.parent
+ return
+ while container is not None and container.type != token.ENDMARKER:
+ if is_fmt_on(container):
+ return
+
+ # fix for fmt: on in children
+ if contains_fmt_on_at_column(container, leaf.column):
+ for child in container.children:
+ if contains_fmt_on_at_column(child, leaf.column):
+ return
+ yield child
+ else:
+ yield container
+ container = container.next_sibling
+
+
+def is_fmt_on(container: LN) -> bool:
+ """Determine whether formatting is switched on within a container.
+ Determined by whether the last `# fmt:` comment is `on` or `off`.
+ """
+ fmt_on = False
+ for comment in list_comments(container.prefix, is_endmarker=False):
+ if comment.value in FMT_ON:
+ fmt_on = True
+ elif comment.value in FMT_OFF:
+ fmt_on = False
+ return fmt_on
+
+
+def contains_fmt_on_at_column(container: LN, column: int) -> bool:
+ """Determine if children at a given column have formatting switched on."""
+ for child in container.children:
+ if (
+ isinstance(child, Node)
+ and first_leaf_column(child) == column
+ or isinstance(child, Leaf)
+ and child.column == column
+ ):
+ if is_fmt_on(child):
+ return True
+
+ return False
+
+
+def contains_pragma_comment(comment_list: List[Leaf]) -> bool:
+ """
+ Returns:
+ True iff one of the comments in @comment_list is a pragma used by one
+ of the more common static analysis tools for python (e.g. mypy, flake8,
+ pylint).
+ """
+ for comment in comment_list:
+ if comment.value.startswith(("# type:", "# noqa", "# pylint:")):
+ return True
+
+ return False
diff --git a/src/black/concurrency.py b/src/black/concurrency.py
new file mode 100644
index 0000000..119a9a7
--- /dev/null
+++ b/src/black/concurrency.py
@@ -0,0 +1,39 @@
+import asyncio
+import logging
+import sys
+from typing import Any, Iterable
+
+from black.output import err
+
+
+def cancel(tasks: Iterable["asyncio.Task[Any]"]) -> None:
+ """asyncio signal handler that cancels all `tasks` and reports to stderr."""
+ err("Aborted!")
+ for task in tasks:
+ task.cancel()
+
+
+def shutdown(loop: asyncio.AbstractEventLoop) -> None:
+ """Cancel all pending tasks on `loop`, wait for them, and close the loop."""
+ try:
+ if sys.version_info[:2] >= (3, 7):
+ all_tasks = asyncio.all_tasks
+ else:
+ all_tasks = asyncio.Task.all_tasks
+ # This part is borrowed from asyncio/runners.py in Python 3.7b2.
+ to_cancel = [task for task in all_tasks(loop) if not task.done()]
+ if not to_cancel:
+ return
+
+ for task in to_cancel:
+ task.cancel()
+ loop.run_until_complete(
+ asyncio.gather(*to_cancel, loop=loop, return_exceptions=True)
+ )
+ finally:
+ # `concurrent.futures.Future` objects cannot be cancelled once they
+ # are already running. There might be some when the `shutdown()` happened.
+ # Silence their logger's spew about the event loop being closed.
+ cf_logger = logging.getLogger("concurrent.futures")
+ cf_logger.setLevel(logging.CRITICAL)
+ loop.close()
diff --git a/src/black/const.py b/src/black/const.py
new file mode 100644
index 0000000..8212585
--- /dev/null
+++ b/src/black/const.py
@@ -0,0 +1,4 @@
+DEFAULT_LINE_LENGTH = 88
+DEFAULT_EXCLUDES = r"/(\.direnv|\.eggs|\.git|\.hg|\.mypy_cache|\.nox|\.tox|\.venv|venv|\.svn|_build|buck-out|build|dist)/" # noqa: B950
+DEFAULT_INCLUDES = r"\.pyi?$"
+STDIN_PLACEHOLDER = "__BLACK_STDIN_FILENAME__"
diff --git a/src/black/debug.py b/src/black/debug.py
new file mode 100644
index 0000000..5143076
--- /dev/null
+++ b/src/black/debug.py
@@ -0,0 +1,48 @@
+from dataclasses import dataclass
+from typing import Iterator, TypeVar, Union
+
+from blib2to3.pytree import Node, Leaf, type_repr
+from blib2to3.pgen2 import token
+
+from black.nodes import Visitor
+from black.output import out
+from black.parsing import lib2to3_parse
+
+LN = Union[Leaf, Node]
+T = TypeVar("T")
+
+
+@dataclass
+class DebugVisitor(Visitor[T]):
+ tree_depth: int = 0
+
+ def visit_default(self, node: LN) -> Iterator[T]:
+ indent = " " * (2 * self.tree_depth)
+ if isinstance(node, Node):
+ _type = type_repr(node.type)
+ out(f"{indent}{_type}", fg="yellow")
+ self.tree_depth += 1
+ for child in node.children:
+ yield from self.visit(child)
+
+ self.tree_depth -= 1
+ out(f"{indent}/{_type}", fg="yellow", bold=False)
+ else:
+ _type = token.tok_name.get(node.type, str(node.type))
+ out(f"{indent}{_type}", fg="blue", nl=False)
+ if node.prefix:
+ # We don't have to handle prefixes for `Node` objects since
+ # that delegates to the first child anyway.
+ out(f" {node.prefix!r}", fg="green", bold=False, nl=False)
+ out(f" {node.value!r}", fg="blue", bold=False)
+
+ @classmethod
+ def show(cls, code: Union[str, Leaf, Node]) -> None:
+ """Pretty-print the lib2to3 AST of a given string of `code`.
+
+ Convenience method for debugging.
+ """
+ v: DebugVisitor[None] = DebugVisitor()
+ if isinstance(code, str):
+ code = lib2to3_parse(code)
+ list(v.visit(code))
diff --git a/src/black/files.py b/src/black/files.py
new file mode 100644
index 0000000..1be5606
--- /dev/null
+++ b/src/black/files.py
@@ -0,0 +1,241 @@
+from functools import lru_cache
+import io
+import os
+from pathlib import Path
+import sys
+from typing import (
+ Any,
+ Dict,
+ Iterable,
+ Iterator,
+ List,
+ Optional,
+ Pattern,
+ Sequence,
+ Tuple,
+ Union,
+ TYPE_CHECKING,
+)
+
+from pathspec import PathSpec
+import toml
+
+from black.output import err
+from black.report import Report
+
+if TYPE_CHECKING:
+ import colorama # noqa: F401
+
+
+@lru_cache()
+def find_project_root(srcs: Sequence[str]) -> Path:
+ """Return a directory containing .git, .hg, or pyproject.toml.
+
+ That directory will be a common parent of all files and directories
+ passed in `srcs`.
+
+ If no directory in the tree contains a marker that would specify it's the
+ project root, the root of the file system is returned.
+ """
+ if not srcs:
+ return Path("/").resolve()
+
+ path_srcs = [Path(Path.cwd(), src).resolve() for src in srcs]
+
+ # A list of lists of parents for each 'src'. 'src' is included as a
+ # "parent" of itself if it is a directory
+ src_parents = [
+ list(path.parents) + ([path] if path.is_dir() else []) for path in path_srcs
+ ]
+
+ common_base = max(
+ set.intersection(*(set(parents) for parents in src_parents)),
+ key=lambda path: path.parts,
+ )
+
+ for directory in (common_base, *common_base.parents):
+ if (directory / ".git").exists():
+ return directory
+
+ if (directory / ".hg").is_dir():
+ return directory
+
+ if (directory / "pyproject.toml").is_file():
+ return directory
+
+ return directory
+
+
+def find_pyproject_toml(path_search_start: Tuple[str, ...]) -> Optional[str]:
+ """Find the absolute filepath to a pyproject.toml if it exists"""
+ path_project_root = find_project_root(path_search_start)
+ path_pyproject_toml = path_project_root / "pyproject.toml"
+ if path_pyproject_toml.is_file():
+ return str(path_pyproject_toml)
+
+ try:
+ path_user_pyproject_toml = find_user_pyproject_toml()
+ return (
+ str(path_user_pyproject_toml)
+ if path_user_pyproject_toml.is_file()
+ else None
+ )
+ except PermissionError as e:
+ # We do not have access to the user-level config directory, so ignore it.
+ err(f"Ignoring user configuration directory due to {e!r}")
+ return None
+
+
+def parse_pyproject_toml(path_config: str) -> Dict[str, Any]:
+ """Parse a pyproject toml file, pulling out relevant parts for Black
+
+ If parsing fails, will raise a toml.TomlDecodeError
+ """
+ pyproject_toml = toml.load(path_config)
+ config = pyproject_toml.get("tool", {}).get("black", {})
+ return {k.replace("--", "").replace("-", "_"): v for k, v in config.items()}
+
+
+@lru_cache()
+def find_user_pyproject_toml() -> Path:
+ r"""Return the path to the top-level user configuration for black.
+
+ This looks for ~\.black on Windows and ~/.config/black on Linux and other
+ Unix systems.
+ """
+ if sys.platform == "win32":
+ # Windows
+ user_config_path = Path.home() / ".black"
+ else:
+ config_root = os.environ.get("XDG_CONFIG_HOME", "~/.config")
+ user_config_path = Path(config_root).expanduser() / "black"
+ return user_config_path.resolve()
+
+
+@lru_cache()
+def get_gitignore(root: Path) -> PathSpec:
+ """Return a PathSpec matching gitignore content if present."""
+ gitignore = root / ".gitignore"
+ lines: List[str] = []
+ if gitignore.is_file():
+ with gitignore.open() as gf:
+ lines = gf.readlines()
+ return PathSpec.from_lines("gitwildmatch", lines)
+
+
+def normalize_path_maybe_ignore(
+ path: Path, root: Path, report: Report
+) -> Optional[str]:
+ """Normalize `path`. May return `None` if `path` was ignored.
+
+ `report` is where "path ignored" output goes.
+ """
+ try:
+ abspath = path if path.is_absolute() else Path.cwd() / path
+ normalized_path = abspath.resolve().relative_to(root).as_posix()
+ except OSError as e:
+ report.path_ignored(path, f"cannot be read because {e}")
+ return None
+
+ except ValueError:
+ if path.is_symlink():
+ report.path_ignored(path, f"is a symbolic link that points outside {root}")
+ return None
+
+ raise
+
+ return normalized_path
+
+
+def path_is_excluded(
+ normalized_path: str,
+ pattern: Optional[Pattern[str]],
+) -> bool:
+ match = pattern.search(normalized_path) if pattern else None
+ return bool(match and match.group(0))
+
+
+def gen_python_files(
+ paths: Iterable[Path],
+ root: Path,
+ include: Pattern[str],
+ exclude: Pattern[str],
+ extend_exclude: Optional[Pattern[str]],
+ force_exclude: Optional[Pattern[str]],
+ report: Report,
+ gitignore: Optional[PathSpec],
+) -> Iterator[Path]:
+ """Generate all files under `path` whose paths are not excluded by the
+ `exclude_regex`, `extend_exclude`, or `force_exclude` regexes,
+ but are included by the `include` regex.
+
+ Symbolic links pointing outside of the `root` directory are ignored.
+
+ `report` is where output about exclusions goes.
+ """
+ assert root.is_absolute(), f"INTERNAL ERROR: `root` must be absolute but is {root}"
+ for child in paths:
+ normalized_path = normalize_path_maybe_ignore(child, root, report)
+ if normalized_path is None:
+ continue
+
+ # First ignore files matching .gitignore, if passed
+ if gitignore is not None and gitignore.match_file(normalized_path):
+ report.path_ignored(child, "matches the .gitignore file content")
+ continue
+
+ # Then ignore with `--exclude` `--extend-exclude` and `--force-exclude` options.
+ normalized_path = "/" + normalized_path
+ if child.is_dir():
+ normalized_path += "/"
+
+ if path_is_excluded(normalized_path, exclude):
+ report.path_ignored(child, "matches the --exclude regular expression")
+ continue
+
+ if path_is_excluded(normalized_path, extend_exclude):
+ report.path_ignored(
+ child, "matches the --extend-exclude regular expression"
+ )
+ continue
+
+ if path_is_excluded(normalized_path, force_exclude):
+ report.path_ignored(child, "matches the --force-exclude regular expression")
+ continue
+
+ if child.is_dir():
+ yield from gen_python_files(
+ child.iterdir(),
+ root,
+ include,
+ exclude,
+ extend_exclude,
+ force_exclude,
+ report,
+ gitignore,
+ )
+
+ elif child.is_file():
+ include_match = include.search(normalized_path) if include else True
+ if include_match:
+ yield child
+
+
+def wrap_stream_for_windows(
+ f: io.TextIOWrapper,
+) -> Union[io.TextIOWrapper, "colorama.AnsiToWin32"]:
+ """
+ Wrap stream with colorama's wrap_stream so colors are shown on Windows.
+
+ If `colorama` is unavailable, the original stream is returned unmodified.
+ Otherwise, the `wrap_stream()` function determines whether the stream needs
+ to be wrapped for a Windows environment and will accordingly either return
+ an `AnsiToWin32` wrapper or the original stream.
+ """
+ try:
+ from colorama.initialise import wrap_stream
+ except ImportError:
+ return f
+ else:
+ # Set `strip=False` to avoid needing to modify test_express_diff_with_color.
+ return wrap_stream(f, convert=None, strip=False, autoreset=False, wrap=True)
diff --git a/src/black/linegen.py b/src/black/linegen.py
new file mode 100644
index 0000000..2e16b6f
--- /dev/null
+++ b/src/black/linegen.py
@@ -0,0 +1,984 @@
+"""
+Generating lines of code.
+"""
+from functools import partial, wraps
+import sys
+from typing import Collection, Iterator, List, Optional, Set, Union
+
+from dataclasses import dataclass, field
+
+from black.nodes import WHITESPACE, STATEMENT, STANDALONE_COMMENT
+from black.nodes import ASSIGNMENTS, OPENING_BRACKETS, CLOSING_BRACKETS
+from black.nodes import Visitor, syms, first_child_is_arith, ensure_visible
+from black.nodes import is_docstring, is_empty_tuple, is_one_tuple, is_one_tuple_between
+from black.nodes import is_walrus_assignment, is_yield, is_vararg, is_multiline_string
+from black.nodes import is_stub_suite, is_stub_body, is_atom_with_invisible_parens
+from black.nodes import wrap_in_parentheses
+from black.brackets import max_delimiter_priority_in_atom
+from black.brackets import DOT_PRIORITY, COMMA_PRIORITY
+from black.lines import Line, line_to_string, is_line_short_enough
+from black.lines import can_omit_invisible_parens, can_be_split, append_leaves
+from black.comments import generate_comments, list_comments, FMT_OFF
+from black.numerics import normalize_numeric_literal
+from black.strings import get_string_prefix, fix_docstring
+from black.strings import normalize_string_prefix, normalize_string_quotes
+from black.trans import Transformer, CannotTransform, StringMerger
+from black.trans import StringSplitter, StringParenWrapper, StringParenStripper
+from black.mode import Mode
+from black.mode import Feature
+
+from blib2to3.pytree import Node, Leaf
+from blib2to3.pgen2 import token
+
+
+# types
+LeafID = int
+LN = Union[Leaf, Node]
+
+
+class CannotSplit(CannotTransform):
+ """A readable split that fits the allotted line length is impossible."""
+
+
+@dataclass
+class LineGenerator(Visitor[Line]):
+ """Generates reformatted Line objects. Empty lines are not emitted.
+
+ Note: destroys the tree it's visiting by mutating prefixes of its leaves
+ in ways that will no longer stringify to valid Python code on the tree.
+ """
+
+ mode: Mode
+ remove_u_prefix: bool = False
+ current_line: Line = field(init=False)
+
+ def line(self, indent: int = 0) -> Iterator[Line]:
+ """Generate a line.
+
+ If the line is empty, only emit if it makes sense.
+ If the line is too long, split it first and then generate.
+
+ If any lines were generated, set up a new current_line.
+ """
+ if not self.current_line:
+ self.current_line.depth += indent
+ return # Line is empty, don't emit. Creating a new one unnecessary.
+
+ complete_line = self.current_line
+ self.current_line = Line(mode=self.mode, depth=complete_line.depth + indent)
+ yield complete_line
+
+ def visit_default(self, node: LN) -> Iterator[Line]:
+ """Default `visit_*()` implementation. Recurses to children of `node`."""
+ if isinstance(node, Leaf):
+ any_open_brackets = self.current_line.bracket_tracker.any_open_brackets()
+ for comment in generate_comments(node):
+ if any_open_brackets:
+ # any comment within brackets is subject to splitting
+ self.current_line.append(comment)
+ elif comment.type == token.COMMENT:
+ # regular trailing comment
+ self.current_line.append(comment)
+ yield from self.line()
+
+ else:
+ # regular standalone comment
+ yield from self.line()
+
+ self.current_line.append(comment)
+ yield from self.line()
+
+ normalize_prefix(node, inside_brackets=any_open_brackets)
+ if self.mode.string_normalization and node.type == token.STRING:
+ node.value = normalize_string_prefix(
+ node.value, remove_u_prefix=self.remove_u_prefix
+ )
+ node.value = normalize_string_quotes(node.value)
+ if node.type == token.NUMBER:
+ normalize_numeric_literal(node)
+ if node.type not in WHITESPACE:
+ self.current_line.append(node)
+ yield from super().visit_default(node)
+
+ def visit_INDENT(self, node: Leaf) -> Iterator[Line]:
+ """Increase indentation level, maybe yield a line."""
+ # In blib2to3 INDENT never holds comments.
+ yield from self.line(+1)
+ yield from self.visit_default(node)
+
+ def visit_DEDENT(self, node: Leaf) -> Iterator[Line]:
+ """Decrease indentation level, maybe yield a line."""
+ # The current line might still wait for trailing comments. At DEDENT time
+ # there won't be any (they would be prefixes on the preceding NEWLINE).
+ # Emit the line then.
+ yield from self.line()
+
+ # While DEDENT has no value, its prefix may contain standalone comments
+ # that belong to the current indentation level. Get 'em.
+ yield from self.visit_default(node)
+
+ # Finally, emit the dedent.
+ yield from self.line(-1)
+
+ def visit_stmt(
+ self, node: Node, keywords: Set[str], parens: Set[str]
+ ) -> Iterator[Line]:
+ """Visit a statement.
+
+ This implementation is shared for `if`, `while`, `for`, `try`, `except`,
+ `def`, `with`, `class`, `assert` and assignments.
+
+ The relevant Python language `keywords` for a given statement will be
+ NAME leaves within it. This methods puts those on a separate line.
+
+ `parens` holds a set of string leaf values immediately after which
+ invisible parens should be put.
+ """
+ normalize_invisible_parens(node, parens_after=parens)
+ for child in node.children:
+ if child.type == token.NAME and child.value in keywords: # type: ignore
+ yield from self.line()
+
+ yield from self.visit(child)
+
+ def visit_suite(self, node: Node) -> Iterator[Line]:
+ """Visit a suite."""
+ if self.mode.is_pyi and is_stub_suite(node):
+ yield from self.visit(node.children[2])
+ else:
+ yield from self.visit_default(node)
+
+ def visit_simple_stmt(self, node: Node) -> Iterator[Line]:
+ """Visit a statement without nested statements."""
+ if first_child_is_arith(node):
+ wrap_in_parentheses(node, node.children[0], visible=False)
+ is_suite_like = node.parent and node.parent.type in STATEMENT
+ if is_suite_like:
+ if self.mode.is_pyi and is_stub_body(node):
+ yield from self.visit_default(node)
+ else:
+ yield from self.line(+1)
+ yield from self.visit_default(node)
+ yield from self.line(-1)
+
+ else:
+ if (
+ not self.mode.is_pyi
+ or not node.parent
+ or not is_stub_suite(node.parent)
+ ):
+ yield from self.line()
+ yield from self.visit_default(node)
+
+ def visit_async_stmt(self, node: Node) -> Iterator[Line]:
+ """Visit `async def`, `async for`, `async with`."""
+ yield from self.line()
+
+ children = iter(node.children)
+ for child in children:
+ yield from self.visit(child)
+
+ if child.type == token.ASYNC:
+ break
+
+ internal_stmt = next(children)
+ for child in internal_stmt.children:
+ yield from self.visit(child)
+
+ def visit_decorators(self, node: Node) -> Iterator[Line]:
+ """Visit decorators."""
+ for child in node.children:
+ yield from self.line()
+ yield from self.visit(child)
+
+ def visit_SEMI(self, leaf: Leaf) -> Iterator[Line]:
+ """Remove a semicolon and put the other statement on a separate line."""
+ yield from self.line()
+
+ def visit_ENDMARKER(self, leaf: Leaf) -> Iterator[Line]:
+ """End of file. Process outstanding comments and end with a newline."""
+ yield from self.visit_default(leaf)
+ yield from self.line()
+
+ def visit_STANDALONE_COMMENT(self, leaf: Leaf) -> Iterator[Line]:
+ if not self.current_line.bracket_tracker.any_open_brackets():
+ yield from self.line()
+ yield from self.visit_default(leaf)
+
+ def visit_factor(self, node: Node) -> Iterator[Line]:
+ """Force parentheses between a unary op and a binary power:
+
+ -2 ** 8 -> -(2 ** 8)
+ """
+ _operator, operand = node.children
+ if (
+ operand.type == syms.power
+ and len(operand.children) == 3
+ and operand.children[1].type == token.DOUBLESTAR
+ ):
+ lpar = Leaf(token.LPAR, "(")
+ rpar = Leaf(token.RPAR, ")")
+ index = operand.remove() or 0
+ node.insert_child(index, Node(syms.atom, [lpar, operand, rpar]))
+ yield from self.visit_default(node)
+
+ def visit_STRING(self, leaf: Leaf) -> Iterator[Line]:
+ if is_docstring(leaf) and "\\\n" not in leaf.value:
+ # We're ignoring docstrings with backslash newline escapes because changing
+ # indentation of those changes the AST representation of the code.
+ prefix = get_string_prefix(leaf.value)
+ docstring = leaf.value[len(prefix) :] # Remove the prefix
+ quote_char = docstring[0]
+ # A natural way to remove the outer quotes is to do:
+ # docstring = docstring.strip(quote_char)
+ # but that breaks on """""x""" (which is '""x').
+ # So we actually need to remove the first character and the next two
+ # characters but only if they are the same as the first.
+ quote_len = 1 if docstring[1] != quote_char else 3
+ docstring = docstring[quote_len:-quote_len]
+
+ if is_multiline_string(leaf):
+ indent = " " * 4 * self.current_line.depth
+ docstring = fix_docstring(docstring, indent)
+ else:
+ docstring = docstring.strip()
+
+ if docstring:
+ # Add some padding if the docstring starts / ends with a quote mark.
+ if docstring[0] == quote_char:
+ docstring = " " + docstring
+ if docstring[-1] == quote_char:
+ docstring += " "
+ if docstring[-1] == "\\":
+ backslash_count = len(docstring) - len(docstring.rstrip("\\"))
+ if backslash_count % 2:
+ # Odd number of tailing backslashes, add some padding to
+ # avoid escaping the closing string quote.
+ docstring += " "
+ else:
+ # Add some padding if the docstring is empty.
+ docstring = " "
+
+ # We could enforce triple quotes at this point.
+ quote = quote_char * quote_len
+ leaf.value = prefix + quote + docstring + quote
+
+ yield from self.visit_default(leaf)
+
+ def __post_init__(self) -> None:
+ """You are in a twisty little maze of passages."""
+ self.current_line = Line(mode=self.mode)
+
+ v = self.visit_stmt
+ Ã: Set[str] = set()
+ self.visit_assert_stmt = partial(v, keywords={"assert"}, parens={"assert", ","})
+ self.visit_if_stmt = partial(
+ v, keywords={"if", "else", "elif"}, parens={"if", "elif"}
+ )
+ self.visit_while_stmt = partial(v, keywords={"while", "else"}, parens={"while"})
+ self.visit_for_stmt = partial(v, keywords={"for", "else"}, parens={"for", "in"})
+ self.visit_try_stmt = partial(
+ v, keywords={"try", "except", "else", "finally"}, parens=Ã
+ )
+ self.visit_except_clause = partial(v, keywords={"except"}, parens=Ã)
+ self.visit_with_stmt = partial(v, keywords={"with"}, parens=Ã)
+ self.visit_funcdef = partial(v, keywords={"def"}, parens=Ã)
+ self.visit_classdef = partial(v, keywords={"class"}, parens=Ã)
+ self.visit_expr_stmt = partial(v, keywords=Ã, parens=ASSIGNMENTS)
+ self.visit_return_stmt = partial(v, keywords={"return"}, parens={"return"})
+ self.visit_import_from = partial(v, keywords=Ã, parens={"import"})
+ self.visit_del_stmt = partial(v, keywords=Ã, parens={"del"})
+ self.visit_async_funcdef = self.visit_async_stmt
+ self.visit_decorated = self.visit_decorators
+
+
+def transform_line(
+ line: Line, mode: Mode, features: Collection[Feature] = ()
+) -> Iterator[Line]:
+ """Transform a `line`, potentially splitting it into many lines.
+
+ They should fit in the allotted `line_length` but might not be able to.
+
+ `features` are syntactical features that may be used in the output.
+ """
+ if line.is_comment:
+ yield line
+ return
+
+ line_str = line_to_string(line)
+
+ ll = mode.line_length
+ sn = mode.string_normalization
+ string_merge = StringMerger(ll, sn)
+ string_paren_strip = StringParenStripper(ll, sn)
+ string_split = StringSplitter(ll, sn)
+ string_paren_wrap = StringParenWrapper(ll, sn)
+
+ transformers: List[Transformer]
+ if (
+ not line.contains_uncollapsable_type_comments()
+ and not line.should_split_rhs
+ and not line.magic_trailing_comma
+ and (
+ is_line_short_enough(line, line_length=mode.line_length, line_str=line_str)
+ or line.contains_unsplittable_type_ignore()
+ )
+ and not (line.inside_brackets and line.contains_standalone_comments())
+ ):
+ # Only apply basic string preprocessing, since lines shouldn't be split here.
+ if mode.experimental_string_processing:
+ transformers = [string_merge, string_paren_strip]
+ else:
+ transformers = []
+ elif line.is_def:
+ transformers = [left_hand_split]
+ else:
+
+ def rhs(line: Line, features: Collection[Feature]) -> Iterator[Line]:
+ """Wraps calls to `right_hand_split`.
+
+ The calls increasingly `omit` right-hand trailers (bracket pairs with
+ content), meaning the trailers get glued together to split on another
+ bracket pair instead.
+ """
+ for omit in generate_trailers_to_omit(line, mode.line_length):
+ lines = list(
+ right_hand_split(line, mode.line_length, features, omit=omit)
+ )
+ # Note: this check is only able to figure out if the first line of the
+ # *current* transformation fits in the line length. This is true only
+ # for simple cases. All others require running more transforms via
+ # `transform_line()`. This check doesn't know if those would succeed.
+ if is_line_short_enough(lines[0], line_length=mode.line_length):
+ yield from lines
+ return
+
+ # All splits failed, best effort split with no omits.
+ # This mostly happens to multiline strings that are by definition
+ # reported as not fitting a single line, as well as lines that contain
+ # trailing commas (those have to be exploded).
+ yield from right_hand_split(
+ line, line_length=mode.line_length, features=features
+ )
+
+ if mode.experimental_string_processing:
+ if line.inside_brackets:
+ transformers = [
+ string_merge,
+ string_paren_strip,
+ string_split,
+ delimiter_split,
+ standalone_comment_split,
+ string_paren_wrap,
+ rhs,
+ ]
+ else:
+ transformers = [
+ string_merge,
+ string_paren_strip,
+ string_split,
+ string_paren_wrap,
+ rhs,
+ ]
+ else:
+ if line.inside_brackets:
+ transformers = [delimiter_split, standalone_comment_split, rhs]
+ else:
+ transformers = [rhs]
+
+ for transform in transformers:
+ # We are accumulating lines in `result` because we might want to abort
+ # mission and return the original line in the end, or attempt a different
+ # split altogether.
+ try:
+ result = run_transformer(line, transform, mode, features, line_str=line_str)
+ except CannotTransform:
+ continue
+ else:
+ yield from result
+ break
+
+ else:
+ yield line
+
+
+def left_hand_split(line: Line, _features: Collection[Feature] = ()) -> Iterator[Line]:
+ """Split line into many lines, starting with the first matching bracket pair.
+
+ Note: this usually looks weird, only use this for function definitions.
+ Prefer RHS otherwise. This is why this function is not symmetrical with
+ :func:`right_hand_split` which also handles optional parentheses.
+ """
+ tail_leaves: List[Leaf] = []
+ body_leaves: List[Leaf] = []
+ head_leaves: List[Leaf] = []
+ current_leaves = head_leaves
+ matching_bracket: Optional[Leaf] = None
+ for leaf in line.leaves:
+ if (
+ current_leaves is body_leaves
+ and leaf.type in CLOSING_BRACKETS
+ and leaf.opening_bracket is matching_bracket
+ ):
+ current_leaves = tail_leaves if body_leaves else head_leaves
+ current_leaves.append(leaf)
+ if current_leaves is head_leaves:
+ if leaf.type in OPENING_BRACKETS:
+ matching_bracket = leaf
+ current_leaves = body_leaves
+ if not matching_bracket:
+ raise CannotSplit("No brackets found")
+
+ head = bracket_split_build_line(head_leaves, line, matching_bracket)
+ body = bracket_split_build_line(body_leaves, line, matching_bracket, is_body=True)
+ tail = bracket_split_build_line(tail_leaves, line, matching_bracket)
+ bracket_split_succeeded_or_raise(head, body, tail)
+ for result in (head, body, tail):
+ if result:
+ yield result
+
+
+def right_hand_split(
+ line: Line,
+ line_length: int,
+ features: Collection[Feature] = (),
+ omit: Collection[LeafID] = (),
+) -> Iterator[Line]:
+ """Split line into many lines, starting with the last matching bracket pair.
+
+ If the split was by optional parentheses, attempt splitting without them, too.
+ `omit` is a collection of closing bracket IDs that shouldn't be considered for
+ this split.
+
+ Note: running this function modifies `bracket_depth` on the leaves of `line`.
+ """
+ tail_leaves: List[Leaf] = []
+ body_leaves: List[Leaf] = []
+ head_leaves: List[Leaf] = []
+ current_leaves = tail_leaves
+ opening_bracket: Optional[Leaf] = None
+ closing_bracket: Optional[Leaf] = None
+ for leaf in reversed(line.leaves):
+ if current_leaves is body_leaves:
+ if leaf is opening_bracket:
+ current_leaves = head_leaves if body_leaves else tail_leaves
+ current_leaves.append(leaf)
+ if current_leaves is tail_leaves:
+ if leaf.type in CLOSING_BRACKETS and id(leaf) not in omit:
+ opening_bracket = leaf.opening_bracket
+ closing_bracket = leaf
+ current_leaves = body_leaves
+ if not (opening_bracket and closing_bracket and head_leaves):
+ # If there is no opening or closing_bracket that means the split failed and
+ # all content is in the tail. Otherwise, if `head_leaves` are empty, it means
+ # the matching `opening_bracket` wasn't available on `line` anymore.
+ raise CannotSplit("No brackets found")
+
+ tail_leaves.reverse()
+ body_leaves.reverse()
+ head_leaves.reverse()
+ head = bracket_split_build_line(head_leaves, line, opening_bracket)
+ body = bracket_split_build_line(body_leaves, line, opening_bracket, is_body=True)
+ tail = bracket_split_build_line(tail_leaves, line, opening_bracket)
+ bracket_split_succeeded_or_raise(head, body, tail)
+ if (
+ Feature.FORCE_OPTIONAL_PARENTHESES not in features
+ # the opening bracket is an optional paren
+ and opening_bracket.type == token.LPAR
+ and not opening_bracket.value
+ # the closing bracket is an optional paren
+ and closing_bracket.type == token.RPAR
+ and not closing_bracket.value
+ # it's not an import (optional parens are the only thing we can split on
+ # in this case; attempting a split without them is a waste of time)
+ and not line.is_import
+ # there are no standalone comments in the body
+ and not body.contains_standalone_comments(0)
+ # and we can actually remove the parens
+ and can_omit_invisible_parens(body, line_length, omit_on_explode=omit)
+ ):
+ omit = {id(closing_bracket), *omit}
+ try:
+ yield from right_hand_split(line, line_length, features=features, omit=omit)
+ return
+
+ except CannotSplit:
+ if not (
+ can_be_split(body)
+ or is_line_short_enough(body, line_length=line_length)
+ ):
+ raise CannotSplit(
+ "Splitting failed, body is still too long and can't be split."
+ )
+
+ elif head.contains_multiline_strings() or tail.contains_multiline_strings():
+ raise CannotSplit(
+ "The current optional pair of parentheses is bound to fail to"
+ " satisfy the splitting algorithm because the head or the tail"
+ " contains multiline strings which by definition never fit one"
+ " line."
+ )
+
+ ensure_visible(opening_bracket)
+ ensure_visible(closing_bracket)
+ for result in (head, body, tail):
+ if result:
+ yield result
+
+
+def bracket_split_succeeded_or_raise(head: Line, body: Line, tail: Line) -> None:
+ """Raise :exc:`CannotSplit` if the last left- or right-hand split failed.
+
+ Do nothing otherwise.
+
+ A left- or right-hand split is based on a pair of brackets. Content before
+ (and including) the opening bracket is left on one line, content inside the
+ brackets is put on a separate line, and finally content starting with and
+ following the closing bracket is put on a separate line.
+
+ Those are called `head`, `body`, and `tail`, respectively. If the split
+ produced the same line (all content in `head`) or ended up with an empty `body`
+ and the `tail` is just the closing bracket, then it's considered failed.
+ """
+ tail_len = len(str(tail).strip())
+ if not body:
+ if tail_len == 0:
+ raise CannotSplit("Splitting brackets produced the same line")
+
+ elif tail_len < 3:
+ raise CannotSplit(
+ f"Splitting brackets on an empty body to save {tail_len} characters is"
+ " not worth it"
+ )
+
+
+def bracket_split_build_line(
+ leaves: List[Leaf], original: Line, opening_bracket: Leaf, *, is_body: bool = False
+) -> Line:
+ """Return a new line with given `leaves` and respective comments from `original`.
+
+ If `is_body` is True, the result line is one-indented inside brackets and as such
+ has its first leaf's prefix normalized and a trailing comma added when expected.
+ """
+ result = Line(mode=original.mode, depth=original.depth)
+ if is_body:
+ result.inside_brackets = True
+ result.depth += 1
+ if leaves:
+ # Since body is a new indent level, remove spurious leading whitespace.
+ normalize_prefix(leaves[0], inside_brackets=True)
+ # Ensure a trailing comma for imports and standalone function arguments, but
+ # be careful not to add one after any comments or within type annotations.
+ no_commas = (
+ original.is_def
+ and opening_bracket.value == "("
+ and not any(leaf.type == token.COMMA for leaf in leaves)
+ )
+
+ if original.is_import or no_commas:
+ for i in range(len(leaves) - 1, -1, -1):
+ if leaves[i].type == STANDALONE_COMMENT:
+ continue
+
+ if leaves[i].type != token.COMMA:
+ new_comma = Leaf(token.COMMA, ",")
+ leaves.insert(i + 1, new_comma)
+ break
+
+ # Populate the line
+ for leaf in leaves:
+ result.append(leaf, preformatted=True)
+ for comment_after in original.comments_after(leaf):
+ result.append(comment_after, preformatted=True)
+ if is_body and should_split_line(result, opening_bracket):
+ result.should_split_rhs = True
+ return result
+
+
+def dont_increase_indentation(split_func: Transformer) -> Transformer:
+ """Normalize prefix of the first leaf in every line returned by `split_func`.
+
+ This is a decorator over relevant split functions.
+ """
+
+ @wraps(split_func)
+ def split_wrapper(line: Line, features: Collection[Feature] = ()) -> Iterator[Line]:
+ for line in split_func(line, features):
+ normalize_prefix(line.leaves[0], inside_brackets=True)
+ yield line
+
+ return split_wrapper
+
+
+@dont_increase_indentation
+def delimiter_split(line: Line, features: Collection[Feature] = ()) -> Iterator[Line]:
+ """Split according to delimiters of the highest priority.
+
+ If the appropriate Features are given, the split will add trailing commas
+ also in function signatures and calls that contain `*` and `**`.
+ """
+ try:
+ last_leaf = line.leaves[-1]
+ except IndexError:
+ raise CannotSplit("Line empty")
+
+ bt = line.bracket_tracker
+ try:
+ delimiter_priority = bt.max_delimiter_priority(exclude={id(last_leaf)})
+ except ValueError:
+ raise CannotSplit("No delimiters found")
+
+ if delimiter_priority == DOT_PRIORITY:
+ if bt.delimiter_count_with_priority(delimiter_priority) == 1:
+ raise CannotSplit("Splitting a single attribute from its owner looks wrong")
+
+ current_line = Line(
+ mode=line.mode, depth=line.depth, inside_brackets=line.inside_brackets
+ )
+ lowest_depth = sys.maxsize
+ trailing_comma_safe = True
+
+ def append_to_line(leaf: Leaf) -> Iterator[Line]:
+ """Append `leaf` to current line or to new line if appending impossible."""
+ nonlocal current_line
+ try:
+ current_line.append_safe(leaf, preformatted=True)
+ except ValueError:
+ yield current_line
+
+ current_line = Line(
+ mode=line.mode, depth=line.depth, inside_brackets=line.inside_brackets
+ )
+ current_line.append(leaf)
+
+ for leaf in line.leaves:
+ yield from append_to_line(leaf)
+
+ for comment_after in line.comments_after(leaf):
+ yield from append_to_line(comment_after)
+
+ lowest_depth = min(lowest_depth, leaf.bracket_depth)
+ if leaf.bracket_depth == lowest_depth:
+ if is_vararg(leaf, within={syms.typedargslist}):
+ trailing_comma_safe = (
+ trailing_comma_safe and Feature.TRAILING_COMMA_IN_DEF in features
+ )
+ elif is_vararg(leaf, within={syms.arglist, syms.argument}):
+ trailing_comma_safe = (
+ trailing_comma_safe and Feature.TRAILING_COMMA_IN_CALL in features
+ )
+
+ leaf_priority = bt.delimiters.get(id(leaf))
+ if leaf_priority == delimiter_priority:
+ yield current_line
+
+ current_line = Line(
+ mode=line.mode, depth=line.depth, inside_brackets=line.inside_brackets
+ )
+ if current_line:
+ if (
+ trailing_comma_safe
+ and delimiter_priority == COMMA_PRIORITY
+ and current_line.leaves[-1].type != token.COMMA
+ and current_line.leaves[-1].type != STANDALONE_COMMENT
+ ):
+ new_comma = Leaf(token.COMMA, ",")
+ current_line.append(new_comma)
+ yield current_line
+
+
+@dont_increase_indentation
+def standalone_comment_split(
+ line: Line, features: Collection[Feature] = ()
+) -> Iterator[Line]:
+ """Split standalone comments from the rest of the line."""
+ if not line.contains_standalone_comments(0):
+ raise CannotSplit("Line does not have any standalone comments")
+
+ current_line = Line(
+ mode=line.mode, depth=line.depth, inside_brackets=line.inside_brackets
+ )
+
+ def append_to_line(leaf: Leaf) -> Iterator[Line]:
+ """Append `leaf` to current line or to new line if appending impossible."""
+ nonlocal current_line
+ try:
+ current_line.append_safe(leaf, preformatted=True)
+ except ValueError:
+ yield current_line
+
+ current_line = Line(
+ line.mode, depth=line.depth, inside_brackets=line.inside_brackets
+ )
+ current_line.append(leaf)
+
+ for leaf in line.leaves:
+ yield from append_to_line(leaf)
+
+ for comment_after in line.comments_after(leaf):
+ yield from append_to_line(comment_after)
+
+ if current_line:
+ yield current_line
+
+
+def normalize_prefix(leaf: Leaf, *, inside_brackets: bool) -> None:
+ """Leave existing extra newlines if not `inside_brackets`. Remove everything
+ else.
+
+ Note: don't use backslashes for formatting or you'll lose your voting rights.
+ """
+ if not inside_brackets:
+ spl = leaf.prefix.split("#")
+ if "\\" not in spl[0]:
+ nl_count = spl[-1].count("\n")
+ if len(spl) > 1:
+ nl_count -= 1
+ leaf.prefix = "\n" * nl_count
+ return
+
+ leaf.prefix = ""
+
+
+def normalize_invisible_parens(node: Node, parens_after: Set[str]) -> None:
+ """Make existing optional parentheses invisible or create new ones.
+
+ `parens_after` is a set of string leaf values immediately after which parens
+ should be put.
+
+ Standardizes on visible parentheses for single-element tuples, and keeps
+ existing visible parentheses for other tuples and generator expressions.
+ """
+ for pc in list_comments(node.prefix, is_endmarker=False):
+ if pc.value in FMT_OFF:
+ # This `node` has a prefix with `# fmt: off`, don't mess with parens.
+ return
+ check_lpar = False
+ for index, child in enumerate(list(node.children)):
+ # Fixes a bug where invisible parens are not properly stripped from
+ # assignment statements that contain type annotations.
+ if isinstance(child, Node) and child.type == syms.annassign:
+ normalize_invisible_parens(child, parens_after=parens_after)
+
+ # Add parentheses around long tuple unpacking in assignments.
+ if (
+ index == 0
+ and isinstance(child, Node)
+ and child.type == syms.testlist_star_expr
+ ):
+ check_lpar = True
+
+ if check_lpar:
+ if child.type == syms.atom:
+ if maybe_make_parens_invisible_in_atom(child, parent=node):
+ wrap_in_parentheses(node, child, visible=False)
+ elif is_one_tuple(child):
+ wrap_in_parentheses(node, child, visible=True)
+ elif node.type == syms.import_from:
+ # "import from" nodes store parentheses directly as part of
+ # the statement
+ if child.type == token.LPAR:
+ # make parentheses invisible
+ child.value = "" # type: ignore
+ node.children[-1].value = "" # type: ignore
+ elif child.type != token.STAR:
+ # insert invisible parentheses
+ node.insert_child(index, Leaf(token.LPAR, ""))
+ node.append_child(Leaf(token.RPAR, ""))
+ break
+
+ elif not (isinstance(child, Leaf) and is_multiline_string(child)):
+ wrap_in_parentheses(node, child, visible=False)
+
+ check_lpar = isinstance(child, Leaf) and child.value in parens_after
+
+
+def maybe_make_parens_invisible_in_atom(node: LN, parent: LN) -> bool:
+ """If it's safe, make the parens in the atom `node` invisible, recursively.
+ Additionally, remove repeated, adjacent invisible parens from the atom `node`
+ as they are redundant.
+
+ Returns whether the node should itself be wrapped in invisible parentheses.
+
+ """
+
+ if (
+ node.type != syms.atom
+ or is_empty_tuple(node)
+ or is_one_tuple(node)
+ or (is_yield(node) and parent.type != syms.expr_stmt)
+ or max_delimiter_priority_in_atom(node) >= COMMA_PRIORITY
+ ):
+ return False
+
+ if is_walrus_assignment(node):
+ if parent.type in [
+ syms.annassign,
+ syms.expr_stmt,
+ syms.assert_stmt,
+ syms.return_stmt,
+ # these ones aren't useful to end users, but they do please fuzzers
+ syms.for_stmt,
+ syms.del_stmt,
+ ]:
+ return False
+
+ first = node.children[0]
+ last = node.children[-1]
+ if first.type == token.LPAR and last.type == token.RPAR:
+ middle = node.children[1]
+ # make parentheses invisible
+ first.value = "" # type: ignore
+ last.value = "" # type: ignore
+ maybe_make_parens_invisible_in_atom(middle, parent=parent)
+
+ if is_atom_with_invisible_parens(middle):
+ # Strip the invisible parens from `middle` by replacing
+ # it with the child in-between the invisible parens
+ middle.replace(middle.children[1])
+
+ return False
+
+ return True
+
+
+def should_split_line(line: Line, opening_bracket: Leaf) -> bool:
+ """Should `line` be immediately split with `delimiter_split()` after RHS?"""
+
+ if not (opening_bracket.parent and opening_bracket.value in "[{("):
+ return False
+
+ # We're essentially checking if the body is delimited by commas and there's more
+ # than one of them (we're excluding the trailing comma and if the delimiter priority
+ # is still commas, that means there's more).
+ exclude = set()
+ trailing_comma = False
+ try:
+ last_leaf = line.leaves[-1]
+ if last_leaf.type == token.COMMA:
+ trailing_comma = True
+ exclude.add(id(last_leaf))
+ max_priority = line.bracket_tracker.max_delimiter_priority(exclude=exclude)
+ except (IndexError, ValueError):
+ return False
+
+ return max_priority == COMMA_PRIORITY and (
+ (line.mode.magic_trailing_comma and trailing_comma)
+ # always explode imports
+ or opening_bracket.parent.type in {syms.atom, syms.import_from}
+ )
+
+
+def generate_trailers_to_omit(line: Line, line_length: int) -> Iterator[Set[LeafID]]:
+ """Generate sets of closing bracket IDs that should be omitted in a RHS.
+
+ Brackets can be omitted if the entire trailer up to and including
+ a preceding closing bracket fits in one line.
+
+ Yielded sets are cumulative (contain results of previous yields, too). First
+ set is empty, unless the line should explode, in which case bracket pairs until
+ the one that needs to explode are omitted.
+ """
+
+ omit: Set[LeafID] = set()
+ if not line.magic_trailing_comma:
+ yield omit
+
+ length = 4 * line.depth
+ opening_bracket: Optional[Leaf] = None
+ closing_bracket: Optional[Leaf] = None
+ inner_brackets: Set[LeafID] = set()
+ for index, leaf, leaf_length in line.enumerate_with_length(reversed=True):
+ length += leaf_length
+ if length > line_length:
+ break
+
+ has_inline_comment = leaf_length > len(leaf.value) + len(leaf.prefix)
+ if leaf.type == STANDALONE_COMMENT or has_inline_comment:
+ break
+
+ if opening_bracket:
+ if leaf is opening_bracket:
+ opening_bracket = None
+ elif leaf.type in CLOSING_BRACKETS:
+ prev = line.leaves[index - 1] if index > 0 else None
+ if (
+ prev
+ and prev.type == token.COMMA
+ and not is_one_tuple_between(
+ leaf.opening_bracket, leaf, line.leaves
+ )
+ ):
+ # Never omit bracket pairs with trailing commas.
+ # We need to explode on those.
+ break
+
+ inner_brackets.add(id(leaf))
+ elif leaf.type in CLOSING_BRACKETS:
+ prev = line.leaves[index - 1] if index > 0 else None
+ if prev and prev.type in OPENING_BRACKETS:
+ # Empty brackets would fail a split so treat them as "inner"
+ # brackets (e.g. only add them to the `omit` set if another
+ # pair of brackets was good enough.
+ inner_brackets.add(id(leaf))
+ continue
+
+ if closing_bracket:
+ omit.add(id(closing_bracket))
+ omit.update(inner_brackets)
+ inner_brackets.clear()
+ yield omit
+
+ if (
+ prev
+ and prev.type == token.COMMA
+ and not is_one_tuple_between(leaf.opening_bracket, leaf, line.leaves)
+ ):
+ # Never omit bracket pairs with trailing commas.
+ # We need to explode on those.
+ break
+
+ if leaf.value:
+ opening_bracket = leaf.opening_bracket
+ closing_bracket = leaf
+
+
+def run_transformer(
+ line: Line,
+ transform: Transformer,
+ mode: Mode,
+ features: Collection[Feature],
+ *,
+ line_str: str = "",
+) -> List[Line]:
+ if not line_str:
+ line_str = line_to_string(line)
+ result: List[Line] = []
+ for transformed_line in transform(line, features):
+ if str(transformed_line).strip("\n") == line_str:
+ raise CannotTransform("Line transformer returned an unchanged result")
+
+ result.extend(transform_line(transformed_line, mode=mode, features=features))
+
+ if not (
+ transform.__name__ == "rhs"
+ and line.bracket_tracker.invisible
+ and not any(bracket.value for bracket in line.bracket_tracker.invisible)
+ and not line.contains_multiline_strings()
+ and not result[0].contains_uncollapsable_type_comments()
+ and not result[0].contains_unsplittable_type_ignore()
+ and not is_line_short_enough(result[0], line_length=mode.line_length)
+ ):
+ return result
+
+ line_copy = line.clone()
+ append_leaves(line_copy, line, line.leaves)
+ features_fop = set(features) | {Feature.FORCE_OPTIONAL_PARENTHESES}
+ second_opinion = run_transformer(
+ line_copy, transform, mode, features_fop, line_str=line_str
+ )
+ if all(
+ is_line_short_enough(ln, line_length=mode.line_length) for ln in second_opinion
+ ):
+ result = second_opinion
+ return result
diff --git a/src/black/lines.py b/src/black/lines.py
new file mode 100644
index 0000000..63225c0
--- /dev/null
+++ b/src/black/lines.py
@@ -0,0 +1,734 @@
+from dataclasses import dataclass, field
+import itertools
+import sys
+from typing import (
+ Callable,
+ Collection,
+ Dict,
+ Iterator,
+ List,
+ Optional,
+ Sequence,
+ Tuple,
+ TypeVar,
+ cast,
+)
+
+from blib2to3.pytree import Node, Leaf
+from blib2to3.pgen2 import token
+
+from black.brackets import BracketTracker, DOT_PRIORITY
+from black.mode import Mode
+from black.nodes import STANDALONE_COMMENT, TEST_DESCENDANTS
+from black.nodes import BRACKETS, OPENING_BRACKETS, CLOSING_BRACKETS
+from black.nodes import syms, whitespace, replace_child, child_towards
+from black.nodes import is_multiline_string, is_import, is_type_comment, last_two_except
+from black.nodes import is_one_tuple_between
+
+# types
+T = TypeVar("T")
+Index = int
+LeafID = int
+
+
+@dataclass
+class Line:
+ """Holds leaves and comments. Can be printed with `str(line)`."""
+
+ mode: Mode
+ depth: int = 0
+ leaves: List[Leaf] = field(default_factory=list)
+ # keys ordered like `leaves`
+ comments: Dict[LeafID, List[Leaf]] = field(default_factory=dict)
+ bracket_tracker: BracketTracker = field(default_factory=BracketTracker)
+ inside_brackets: bool = False
+ should_split_rhs: bool = False
+ magic_trailing_comma: Optional[Leaf] = None
+
+ def append(self, leaf: Leaf, preformatted: bool = False) -> None:
+ """Add a new `leaf` to the end of the line.
+
+ Unless `preformatted` is True, the `leaf` will receive a new consistent
+ whitespace prefix and metadata applied by :class:`BracketTracker`.
+ Trailing commas are maybe removed, unpacked for loop variables are
+ demoted from being delimiters.
+
+ Inline comments are put aside.
+ """
+ has_value = leaf.type in BRACKETS or bool(leaf.value.strip())
+ if not has_value:
+ return
+
+ if token.COLON == leaf.type and self.is_class_paren_empty:
+ del self.leaves[-2:]
+ if self.leaves and not preformatted:
+ # Note: at this point leaf.prefix should be empty except for
+ # imports, for which we only preserve newlines.
+ leaf.prefix += whitespace(
+ leaf, complex_subscript=self.is_complex_subscript(leaf)
+ )
+ if self.inside_brackets or not preformatted:
+ self.bracket_tracker.mark(leaf)
+ if self.mode.magic_trailing_comma:
+ if self.has_magic_trailing_comma(leaf):
+ self.magic_trailing_comma = leaf
+ elif self.has_magic_trailing_comma(leaf, ensure_removable=True):
+ self.remove_trailing_comma()
+ if not self.append_comment(leaf):
+ self.leaves.append(leaf)
+
+ def append_safe(self, leaf: Leaf, preformatted: bool = False) -> None:
+ """Like :func:`append()` but disallow invalid standalone comment structure.
+
+ Raises ValueError when any `leaf` is appended after a standalone comment
+ or when a standalone comment is not the first leaf on the line.
+ """
+ if self.bracket_tracker.depth == 0:
+ if self.is_comment:
+ raise ValueError("cannot append to standalone comments")
+
+ if self.leaves and leaf.type == STANDALONE_COMMENT:
+ raise ValueError(
+ "cannot append standalone comments to a populated line"
+ )
+
+ self.append(leaf, preformatted=preformatted)
+
+ @property
+ def is_comment(self) -> bool:
+ """Is this line a standalone comment?"""
+ return len(self.leaves) == 1 and self.leaves[0].type == STANDALONE_COMMENT
+
+ @property
+ def is_decorator(self) -> bool:
+ """Is this line a decorator?"""
+ return bool(self) and self.leaves[0].type == token.AT
+
+ @property
+ def is_import(self) -> bool:
+ """Is this an import line?"""
+ return bool(self) and is_import(self.leaves[0])
+
+ @property
+ def is_class(self) -> bool:
+ """Is this line a class definition?"""
+ return (
+ bool(self)
+ and self.leaves[0].type == token.NAME
+ and self.leaves[0].value == "class"
+ )
+
+ @property
+ def is_stub_class(self) -> bool:
+ """Is this line a class definition with a body consisting only of "..."?"""
+ return self.is_class and self.leaves[-3:] == [
+ Leaf(token.DOT, ".") for _ in range(3)
+ ]
+
+ @property
+ def is_def(self) -> bool:
+ """Is this a function definition? (Also returns True for async defs.)"""
+ try:
+ first_leaf = self.leaves[0]
+ except IndexError:
+ return False
+
+ try:
+ second_leaf: Optional[Leaf] = self.leaves[1]
+ except IndexError:
+ second_leaf = None
+ return (first_leaf.type == token.NAME and first_leaf.value == "def") or (
+ first_leaf.type == token.ASYNC
+ and second_leaf is not None
+ and second_leaf.type == token.NAME
+ and second_leaf.value == "def"
+ )
+
+ @property
+ def is_class_paren_empty(self) -> bool:
+ """Is this a class with no base classes but using parentheses?
+
+ Those are unnecessary and should be removed.
+ """
+ return (
+ bool(self)
+ and len(self.leaves) == 4
+ and self.is_class
+ and self.leaves[2].type == token.LPAR
+ and self.leaves[2].value == "("
+ and self.leaves[3].type == token.RPAR
+ and self.leaves[3].value == ")"
+ )
+
+ @property
+ def is_triple_quoted_string(self) -> bool:
+ """Is the line a triple quoted string?"""
+ return (
+ bool(self)
+ and self.leaves[0].type == token.STRING
+ and self.leaves[0].value.startswith(('"""', "'''"))
+ )
+
+ def contains_standalone_comments(self, depth_limit: int = sys.maxsize) -> bool:
+ """If so, needs to be split before emitting."""
+ for leaf in self.leaves:
+ if leaf.type == STANDALONE_COMMENT and leaf.bracket_depth <= depth_limit:
+ return True
+
+ return False
+
+ def contains_uncollapsable_type_comments(self) -> bool:
+ ignored_ids = set()
+ try:
+ last_leaf = self.leaves[-1]
+ ignored_ids.add(id(last_leaf))
+ if last_leaf.type == token.COMMA or (
+ last_leaf.type == token.RPAR and not last_leaf.value
+ ):
+ # When trailing commas or optional parens are inserted by Black for
+ # consistency, comments after the previous last element are not moved
+ # (they don't have to, rendering will still be correct). So we ignore
+ # trailing commas and invisible.
+ last_leaf = self.leaves[-2]
+ ignored_ids.add(id(last_leaf))
+ except IndexError:
+ return False
+
+ # A type comment is uncollapsable if it is attached to a leaf
+ # that isn't at the end of the line (since that could cause it
+ # to get associated to a different argument) or if there are
+ # comments before it (since that could cause it to get hidden
+ # behind a comment.
+ comment_seen = False
+ for leaf_id, comments in self.comments.items():
+ for comment in comments:
+ if is_type_comment(comment):
+ if comment_seen or (
+ not is_type_comment(comment, " ignore")
+ and leaf_id not in ignored_ids
+ ):
+ return True
+
+ comment_seen = True
+
+ return False
+
+ def contains_unsplittable_type_ignore(self) -> bool:
+ if not self.leaves:
+ return False
+
+ # If a 'type: ignore' is attached to the end of a line, we
+ # can't split the line, because we can't know which of the
+ # subexpressions the ignore was meant to apply to.
+ #
+ # We only want this to apply to actual physical lines from the
+ # original source, though: we don't want the presence of a
+ # 'type: ignore' at the end of a multiline expression to
+ # justify pushing it all onto one line. Thus we
+ # (unfortunately) need to check the actual source lines and
+ # only report an unsplittable 'type: ignore' if this line was
+ # one line in the original code.
+
+ # Grab the first and last line numbers, skipping generated leaves
+ first_line = next((leaf.lineno for leaf in self.leaves if leaf.lineno != 0), 0)
+ last_line = next(
+ (leaf.lineno for leaf in reversed(self.leaves) if leaf.lineno != 0), 0
+ )
+
+ if first_line == last_line:
+ # We look at the last two leaves since a comma or an
+ # invisible paren could have been added at the end of the
+ # line.
+ for node in self.leaves[-2:]:
+ for comment in self.comments.get(id(node), []):
+ if is_type_comment(comment, " ignore"):
+ return True
+
+ return False
+
+ def contains_multiline_strings(self) -> bool:
+ return any(is_multiline_string(leaf) for leaf in self.leaves)
+
+ def has_magic_trailing_comma(
+ self, closing: Leaf, ensure_removable: bool = False
+ ) -> bool:
+ """Return True if we have a magic trailing comma, that is when:
+ - there's a trailing comma here
+ - it's not a one-tuple
+ Additionally, if ensure_removable:
+ - it's not from square bracket indexing
+ """
+ if not (
+ closing.type in CLOSING_BRACKETS
+ and self.leaves
+ and self.leaves[-1].type == token.COMMA
+ ):
+ return False
+
+ if closing.type == token.RBRACE:
+ return True
+
+ if closing.type == token.RSQB:
+ if not ensure_removable:
+ return True
+ comma = self.leaves[-1]
+ return bool(comma.parent and comma.parent.type == syms.listmaker)
+
+ if self.is_import:
+ return True
+
+ if not is_one_tuple_between(closing.opening_bracket, closing, self.leaves):
+ return True
+
+ return False
+
+ def append_comment(self, comment: Leaf) -> bool:
+ """Add an inline or standalone comment to the line."""
+ if (
+ comment.type == STANDALONE_COMMENT
+ and self.bracket_tracker.any_open_brackets()
+ ):
+ comment.prefix = ""
+ return False
+
+ if comment.type != token.COMMENT:
+ return False
+
+ if not self.leaves:
+ comment.type = STANDALONE_COMMENT
+ comment.prefix = ""
+ return False
+
+ last_leaf = self.leaves[-1]
+ if (
+ last_leaf.type == token.RPAR
+ and not last_leaf.value
+ and last_leaf.parent
+ and len(list(last_leaf.parent.leaves())) <= 3
+ and not is_type_comment(comment)
+ ):
+ # Comments on an optional parens wrapping a single leaf should belong to
+ # the wrapped node except if it's a type comment. Pinning the comment like
+ # this avoids unstable formatting caused by comment migration.
+ if len(self.leaves) < 2:
+ comment.type = STANDALONE_COMMENT
+ comment.prefix = ""
+ return False
+
+ last_leaf = self.leaves[-2]
+ self.comments.setdefault(id(last_leaf), []).append(comment)
+ return True
+
+ def comments_after(self, leaf: Leaf) -> List[Leaf]:
+ """Generate comments that should appear directly after `leaf`."""
+ return self.comments.get(id(leaf), [])
+
+ def remove_trailing_comma(self) -> None:
+ """Remove the trailing comma and moves the comments attached to it."""
+ trailing_comma = self.leaves.pop()
+ trailing_comma_comments = self.comments.pop(id(trailing_comma), [])
+ self.comments.setdefault(id(self.leaves[-1]), []).extend(
+ trailing_comma_comments
+ )
+
+ def is_complex_subscript(self, leaf: Leaf) -> bool:
+ """Return True iff `leaf` is part of a slice with non-trivial exprs."""
+ open_lsqb = self.bracket_tracker.get_open_lsqb()
+ if open_lsqb is None:
+ return False
+
+ subscript_start = open_lsqb.next_sibling
+
+ if isinstance(subscript_start, Node):
+ if subscript_start.type == syms.listmaker:
+ return False
+
+ if subscript_start.type == syms.subscriptlist:
+ subscript_start = child_towards(subscript_start, leaf)
+ return subscript_start is not None and any(
+ n.type in TEST_DESCENDANTS for n in subscript_start.pre_order()
+ )
+
+ def enumerate_with_length(
+ self, reversed: bool = False
+ ) -> Iterator[Tuple[Index, Leaf, int]]:
+ """Return an enumeration of leaves with their length.
+
+ Stops prematurely on multiline strings and standalone comments.
+ """
+ op = cast(
+ Callable[[Sequence[Leaf]], Iterator[Tuple[Index, Leaf]]],
+ enumerate_reversed if reversed else enumerate,
+ )
+ for index, leaf in op(self.leaves):
+ length = len(leaf.prefix) + len(leaf.value)
+ if "\n" in leaf.value:
+ return # Multiline strings, we can't continue.
+
+ for comment in self.comments_after(leaf):
+ length += len(comment.value)
+
+ yield index, leaf, length
+
+ def clone(self) -> "Line":
+ return Line(
+ mode=self.mode,
+ depth=self.depth,
+ inside_brackets=self.inside_brackets,
+ should_split_rhs=self.should_split_rhs,
+ magic_trailing_comma=self.magic_trailing_comma,
+ )
+
+ def __str__(self) -> str:
+ """Render the line."""
+ if not self:
+ return "\n"
+
+ indent = " " * self.depth
+ leaves = iter(self.leaves)
+ first = next(leaves)
+ res = f"{first.prefix}{indent}{first.value}"
+ for leaf in leaves:
+ res += str(leaf)
+ for comment in itertools.chain.from_iterable(self.comments.values()):
+ res += str(comment)
+
+ return res + "\n"
+
+ def __bool__(self) -> bool:
+ """Return True if the line has leaves or comments."""
+ return bool(self.leaves or self.comments)
+
+
+@dataclass
+class EmptyLineTracker:
+ """Provides a stateful method that returns the number of potential extra
+ empty lines needed before and after the currently processed line.
+
+ Note: this tracker works on lines that haven't been split yet. It assumes
+ the prefix of the first leaf consists of optional newlines. Those newlines
+ are consumed by `maybe_empty_lines()` and included in the computation.
+ """
+
+ is_pyi: bool = False
+ previous_line: Optional[Line] = None
+ previous_after: int = 0
+ previous_defs: List[int] = field(default_factory=list)
+
+ def maybe_empty_lines(self, current_line: Line) -> Tuple[int, int]:
+ """Return the number of extra empty lines before and after the `current_line`.
+
+ This is for separating `def`, `async def` and `class` with extra empty
+ lines (two on module-level).
+ """
+ before, after = self._maybe_empty_lines(current_line)
+ before = (
+ # Black should not insert empty lines at the beginning
+ # of the file
+ 0
+ if self.previous_line is None
+ else before - self.previous_after
+ )
+ self.previous_after = after
+ self.previous_line = current_line
+ return before, after
+
+ def _maybe_empty_lines(self, current_line: Line) -> Tuple[int, int]:
+ max_allowed = 1
+ if current_line.depth == 0:
+ max_allowed = 1 if self.is_pyi else 2
+ if current_line.leaves:
+ # Consume the first leaf's extra newlines.
+ first_leaf = current_line.leaves[0]
+ before = first_leaf.prefix.count("\n")
+ before = min(before, max_allowed)
+ first_leaf.prefix = ""
+ else:
+ before = 0
+ depth = current_line.depth
+ while self.previous_defs and self.previous_defs[-1] >= depth:
+ self.previous_defs.pop()
+ if self.is_pyi:
+ before = 0 if depth else 1
+ else:
+ before = 1 if depth else 2
+ if current_line.is_decorator or current_line.is_def or current_line.is_class:
+ return self._maybe_empty_lines_for_class_or_def(current_line, before)
+
+ if (
+ self.previous_line
+ and self.previous_line.is_import
+ and not current_line.is_import
+ and depth == self.previous_line.depth
+ ):
+ return (before or 1), 0
+
+ if (
+ self.previous_line
+ and self.previous_line.is_class
+ and current_line.is_triple_quoted_string
+ ):
+ return before, 1
+
+ return before, 0
+
+ def _maybe_empty_lines_for_class_or_def(
+ self, current_line: Line, before: int
+ ) -> Tuple[int, int]:
+ if not current_line.is_decorator:
+ self.previous_defs.append(current_line.depth)
+ if self.previous_line is None:
+ # Don't insert empty lines before the first line in the file.
+ return 0, 0
+
+ if self.previous_line.is_decorator:
+ if self.is_pyi and current_line.is_stub_class:
+ # Insert an empty line after a decorated stub class
+ return 0, 1
+
+ return 0, 0
+
+ if self.previous_line.depth < current_line.depth and (
+ self.previous_line.is_class or self.previous_line.is_def
+ ):
+ return 0, 0
+
+ if (
+ self.previous_line.is_comment
+ and self.previous_line.depth == current_line.depth
+ and before == 0
+ ):
+ return 0, 0
+
+ if self.is_pyi:
+ if self.previous_line.depth > current_line.depth:
+ newlines = 1
+ elif current_line.is_class or self.previous_line.is_class:
+ if current_line.is_stub_class and self.previous_line.is_stub_class:
+ # No blank line between classes with an empty body
+ newlines = 0
+ else:
+ newlines = 1
+ elif (
+ current_line.is_def or current_line.is_decorator
+ ) and not self.previous_line.is_def:
+ # Blank line between a block of functions (maybe with preceding
+ # decorators) and a block of non-functions
+ newlines = 1
+ else:
+ newlines = 0
+ else:
+ newlines = 2
+ if current_line.depth and newlines:
+ newlines -= 1
+ return newlines, 0
+
+
+def enumerate_reversed(sequence: Sequence[T]) -> Iterator[Tuple[Index, T]]:
+ """Like `reversed(enumerate(sequence))` if that were possible."""
+ index = len(sequence) - 1
+ for element in reversed(sequence):
+ yield (index, element)
+ index -= 1
+
+
+def append_leaves(
+ new_line: Line, old_line: Line, leaves: List[Leaf], preformatted: bool = False
+) -> None:
+ """
+ Append leaves (taken from @old_line) to @new_line, making sure to fix the
+ underlying Node structure where appropriate.
+
+ All of the leaves in @leaves are duplicated. The duplicates are then
+ appended to @new_line and used to replace their originals in the underlying
+ Node structure. Any comments attached to the old leaves are reattached to
+ the new leaves.
+
+ Pre-conditions:
+ set(@leaves) is a subset of set(@old_line.leaves).
+ """
+ for old_leaf in leaves:
+ new_leaf = Leaf(old_leaf.type, old_leaf.value)
+ replace_child(old_leaf, new_leaf)
+ new_line.append(new_leaf, preformatted=preformatted)
+
+ for comment_leaf in old_line.comments_after(old_leaf):
+ new_line.append(comment_leaf, preformatted=True)
+
+
+def is_line_short_enough(line: Line, *, line_length: int, line_str: str = "") -> bool:
+ """Return True if `line` is no longer than `line_length`.
+
+ Uses the provided `line_str` rendering, if any, otherwise computes a new one.
+ """
+ if not line_str:
+ line_str = line_to_string(line)
+ return (
+ len(line_str) <= line_length
+ and "\n" not in line_str # multiline strings
+ and not line.contains_standalone_comments()
+ )
+
+
+def can_be_split(line: Line) -> bool:
+ """Return False if the line cannot be split *for sure*.
+
+ This is not an exhaustive search but a cheap heuristic that we can use to
+ avoid some unfortunate formattings (mostly around wrapping unsplittable code
+ in unnecessary parentheses).
+ """
+ leaves = line.leaves
+ if len(leaves) < 2:
+ return False
+
+ if leaves[0].type == token.STRING and leaves[1].type == token.DOT:
+ call_count = 0
+ dot_count = 0
+ next = leaves[-1]
+ for leaf in leaves[-2::-1]:
+ if leaf.type in OPENING_BRACKETS:
+ if next.type not in CLOSING_BRACKETS:
+ return False
+
+ call_count += 1
+ elif leaf.type == token.DOT:
+ dot_count += 1
+ elif leaf.type == token.NAME:
+ if not (next.type == token.DOT or next.type in OPENING_BRACKETS):
+ return False
+
+ elif leaf.type not in CLOSING_BRACKETS:
+ return False
+
+ if dot_count > 1 and call_count > 1:
+ return False
+
+ return True
+
+
+def can_omit_invisible_parens(
+ line: Line,
+ line_length: int,
+ omit_on_explode: Collection[LeafID] = (),
+) -> bool:
+ """Does `line` have a shape safe to reformat without optional parens around it?
+
+ Returns True for only a subset of potentially nice looking formattings but
+ the point is to not return false positives that end up producing lines that
+ are too long.
+ """
+ bt = line.bracket_tracker
+ if not bt.delimiters:
+ # Without delimiters the optional parentheses are useless.
+ return True
+
+ max_priority = bt.max_delimiter_priority()
+ if bt.delimiter_count_with_priority(max_priority) > 1:
+ # With more than one delimiter of a kind the optional parentheses read better.
+ return False
+
+ if max_priority == DOT_PRIORITY:
+ # A single stranded method call doesn't require optional parentheses.
+ return True
+
+ assert len(line.leaves) >= 2, "Stranded delimiter"
+
+ # With a single delimiter, omit if the expression starts or ends with
+ # a bracket.
+ first = line.leaves[0]
+ second = line.leaves[1]
+ if first.type in OPENING_BRACKETS and second.type not in CLOSING_BRACKETS:
+ if _can_omit_opening_paren(line, first=first, line_length=line_length):
+ return True
+
+ # Note: we are not returning False here because a line might have *both*
+ # a leading opening bracket and a trailing closing bracket. If the
+ # opening bracket doesn't match our rule, maybe the closing will.
+
+ penultimate = line.leaves[-2]
+ last = line.leaves[-1]
+ if line.magic_trailing_comma:
+ try:
+ penultimate, last = last_two_except(line.leaves, omit=omit_on_explode)
+ except LookupError:
+ # Turns out we'd omit everything. We cannot skip the optional parentheses.
+ return False
+
+ if (
+ last.type == token.RPAR
+ or last.type == token.RBRACE
+ or (
+ # don't use indexing for omitting optional parentheses;
+ # it looks weird
+ last.type == token.RSQB
+ and last.parent
+ and last.parent.type != syms.trailer
+ )
+ ):
+ if penultimate.type in OPENING_BRACKETS:
+ # Empty brackets don't help.
+ return False
+
+ if is_multiline_string(first):
+ # Additional wrapping of a multiline string in this situation is
+ # unnecessary.
+ return True
+
+ if line.magic_trailing_comma and penultimate.type == token.COMMA:
+ # The rightmost non-omitted bracket pair is the one we want to explode on.
+ return True
+
+ if _can_omit_closing_paren(line, last=last, line_length=line_length):
+ return True
+
+ return False
+
+
+def _can_omit_opening_paren(line: Line, *, first: Leaf, line_length: int) -> bool:
+ """See `can_omit_invisible_parens`."""
+ remainder = False
+ length = 4 * line.depth
+ _index = -1
+ for _index, leaf, leaf_length in line.enumerate_with_length():
+ if leaf.type in CLOSING_BRACKETS and leaf.opening_bracket is first:
+ remainder = True
+ if remainder:
+ length += leaf_length
+ if length > line_length:
+ break
+
+ if leaf.type in OPENING_BRACKETS:
+ # There are brackets we can further split on.
+ remainder = False
+
+ else:
+ # checked the entire string and line length wasn't exceeded
+ if len(line.leaves) == _index + 1:
+ return True
+
+ return False
+
+
+def _can_omit_closing_paren(line: Line, *, last: Leaf, line_length: int) -> bool:
+ """See `can_omit_invisible_parens`."""
+ length = 4 * line.depth
+ seen_other_brackets = False
+ for _index, leaf, leaf_length in line.enumerate_with_length():
+ length += leaf_length
+ if leaf is last.opening_bracket:
+ if seen_other_brackets or length <= line_length:
+ return True
+
+ elif leaf.type in OPENING_BRACKETS:
+ # There are brackets we can further split on.
+ seen_other_brackets = True
+
+ return False
+
+
+def line_to_string(line: Line) -> str:
+ """Returns the string representation of @line.
+
+ WARNING: This is known to be computationally expensive.
+ """
+ return str(line).strip("\n")
diff --git a/src/black/mode.py b/src/black/mode.py
new file mode 100644
index 0000000..e2ce322
--- /dev/null
+++ b/src/black/mode.py
@@ -0,0 +1,123 @@
+"""Data structures configuring Black behavior.
+
+Mostly around Python language feature support per version and Black configuration
+chosen by the user.
+"""
+
+from dataclasses import dataclass, field
+from enum import Enum
+from typing import Dict, Set
+
+from black.const import DEFAULT_LINE_LENGTH
+
+
+class TargetVersion(Enum):
+ PY27 = 2
+ PY33 = 3
+ PY34 = 4
+ PY35 = 5
+ PY36 = 6
+ PY37 = 7
+ PY38 = 8
+ PY39 = 9
+
+ def is_python2(self) -> bool:
+ return self is TargetVersion.PY27
+
+
+class Feature(Enum):
+ # All string literals are unicode
+ UNICODE_LITERALS = 1
+ F_STRINGS = 2
+ NUMERIC_UNDERSCORES = 3
+ TRAILING_COMMA_IN_CALL = 4
+ TRAILING_COMMA_IN_DEF = 5
+ # The following two feature-flags are mutually exclusive, and exactly one should be
+ # set for every version of python.
+ ASYNC_IDENTIFIERS = 6
+ ASYNC_KEYWORDS = 7
+ ASSIGNMENT_EXPRESSIONS = 8
+ POS_ONLY_ARGUMENTS = 9
+ RELAXED_DECORATORS = 10
+ FORCE_OPTIONAL_PARENTHESES = 50
+
+
+VERSION_TO_FEATURES: Dict[TargetVersion, Set[Feature]] = {
+ TargetVersion.PY27: {Feature.ASYNC_IDENTIFIERS},
+ TargetVersion.PY33: {Feature.UNICODE_LITERALS, Feature.ASYNC_IDENTIFIERS},
+ TargetVersion.PY34: {Feature.UNICODE_LITERALS, Feature.ASYNC_IDENTIFIERS},
+ TargetVersion.PY35: {
+ Feature.UNICODE_LITERALS,
+ Feature.TRAILING_COMMA_IN_CALL,
+ Feature.ASYNC_IDENTIFIERS,
+ },
+ TargetVersion.PY36: {
+ Feature.UNICODE_LITERALS,
+ Feature.F_STRINGS,
+ Feature.NUMERIC_UNDERSCORES,
+ Feature.TRAILING_COMMA_IN_CALL,
+ Feature.TRAILING_COMMA_IN_DEF,
+ Feature.ASYNC_IDENTIFIERS,
+ },
+ TargetVersion.PY37: {
+ Feature.UNICODE_LITERALS,
+ Feature.F_STRINGS,
+ Feature.NUMERIC_UNDERSCORES,
+ Feature.TRAILING_COMMA_IN_CALL,
+ Feature.TRAILING_COMMA_IN_DEF,
+ Feature.ASYNC_KEYWORDS,
+ },
+ TargetVersion.PY38: {
+ Feature.UNICODE_LITERALS,
+ Feature.F_STRINGS,
+ Feature.NUMERIC_UNDERSCORES,
+ Feature.TRAILING_COMMA_IN_CALL,
+ Feature.TRAILING_COMMA_IN_DEF,
+ Feature.ASYNC_KEYWORDS,
+ Feature.ASSIGNMENT_EXPRESSIONS,
+ Feature.POS_ONLY_ARGUMENTS,
+ },
+ TargetVersion.PY39: {
+ Feature.UNICODE_LITERALS,
+ Feature.F_STRINGS,
+ Feature.NUMERIC_UNDERSCORES,
+ Feature.TRAILING_COMMA_IN_CALL,
+ Feature.TRAILING_COMMA_IN_DEF,
+ Feature.ASYNC_KEYWORDS,
+ Feature.ASSIGNMENT_EXPRESSIONS,
+ Feature.RELAXED_DECORATORS,
+ Feature.POS_ONLY_ARGUMENTS,
+ },
+}
+
+
+def supports_feature(target_versions: Set[TargetVersion], feature: Feature) -> bool:
+ return all(feature in VERSION_TO_FEATURES[version] for version in target_versions)
+
+
+@dataclass
+class Mode:
+ target_versions: Set[TargetVersion] = field(default_factory=set)
+ line_length: int = DEFAULT_LINE_LENGTH
+ string_normalization: bool = True
+ is_pyi: bool = False
+ magic_trailing_comma: bool = True
+ experimental_string_processing: bool = False
+
+ def get_cache_key(self) -> str:
+ if self.target_versions:
+ version_str = ",".join(
+ str(version.value)
+ for version in sorted(self.target_versions, key=lambda v: v.value)
+ )
+ else:
+ version_str = "-"
+ parts = [
+ version_str,
+ str(self.line_length),
+ str(int(self.string_normalization)),
+ str(int(self.is_pyi)),
+ str(int(self.magic_trailing_comma)),
+ str(int(self.experimental_string_processing)),
+ ]
+ return ".".join(parts)
diff --git a/src/black/nodes.py b/src/black/nodes.py
new file mode 100644
index 0000000..e0db9a4
--- /dev/null
+++ b/src/black/nodes.py
@@ -0,0 +1,843 @@
+"""
+blib2to3 Node/Leaf transformation-related utility functions.
+"""
+
+import sys
+from typing import (
+ Collection,
+ Generic,
+ Iterator,
+ List,
+ Optional,
+ Set,
+ Tuple,
+ TypeVar,
+ Union,
+)
+
+if sys.version_info < (3, 8):
+ from typing_extensions import Final
+else:
+ from typing import Final
+
+# lib2to3 fork
+from blib2to3.pytree import Node, Leaf, type_repr
+from blib2to3 import pygram
+from blib2to3.pgen2 import token
+
+from black.cache import CACHE_DIR
+from black.strings import has_triple_quotes
+
+
+pygram.initialize(CACHE_DIR)
+syms = pygram.python_symbols
+
+
+# types
+T = TypeVar("T")
+LN = Union[Leaf, Node]
+LeafID = int
+NodeType = int
+
+
+WHITESPACE: Final = {token.DEDENT, token.INDENT, token.NEWLINE}
+STATEMENT: Final = {
+ syms.if_stmt,
+ syms.while_stmt,
+ syms.for_stmt,
+ syms.try_stmt,
+ syms.except_clause,
+ syms.with_stmt,
+ syms.funcdef,
+ syms.classdef,
+}
+STANDALONE_COMMENT: Final = 153
+token.tok_name[STANDALONE_COMMENT] = "STANDALONE_COMMENT"
+LOGIC_OPERATORS: Final = {"and", "or"}
+COMPARATORS: Final = {
+ token.LESS,
+ token.GREATER,
+ token.EQEQUAL,
+ token.NOTEQUAL,
+ token.LESSEQUAL,
+ token.GREATEREQUAL,
+}
+MATH_OPERATORS: Final = {
+ token.VBAR,
+ token.CIRCUMFLEX,
+ token.AMPER,
+ token.LEFTSHIFT,
+ token.RIGHTSHIFT,
+ token.PLUS,
+ token.MINUS,
+ token.STAR,
+ token.SLASH,
+ token.DOUBLESLASH,
+ token.PERCENT,
+ token.AT,
+ token.TILDE,
+ token.DOUBLESTAR,
+}
+STARS: Final = {token.STAR, token.DOUBLESTAR}
+VARARGS_SPECIALS: Final = STARS | {token.SLASH}
+VARARGS_PARENTS: Final = {
+ syms.arglist,
+ syms.argument, # double star in arglist
+ syms.trailer, # single argument to call
+ syms.typedargslist,
+ syms.varargslist, # lambdas
+}
+UNPACKING_PARENTS: Final = {
+ syms.atom, # single element of a list or set literal
+ syms.dictsetmaker,
+ syms.listmaker,
+ syms.testlist_gexp,
+ syms.testlist_star_expr,
+}
+TEST_DESCENDANTS: Final = {
+ syms.test,
+ syms.lambdef,
+ syms.or_test,
+ syms.and_test,
+ syms.not_test,
+ syms.comparison,
+ syms.star_expr,
+ syms.expr,
+ syms.xor_expr,
+ syms.and_expr,
+ syms.shift_expr,
+ syms.arith_expr,
+ syms.trailer,
+ syms.term,
+ syms.power,
+}
+ASSIGNMENTS: Final = {
+ "=",
+ "+=",
+ "-=",
+ "*=",
+ "@=",
+ "/=",
+ "%=",
+ "&=",
+ "|=",
+ "^=",
+ "<<=",
+ ">>=",
+ "**=",
+ "//=",
+}
+
+IMPLICIT_TUPLE = {syms.testlist, syms.testlist_star_expr, syms.exprlist}
+BRACKET = {token.LPAR: token.RPAR, token.LSQB: token.RSQB, token.LBRACE: token.RBRACE}
+OPENING_BRACKETS = set(BRACKET.keys())
+CLOSING_BRACKETS = set(BRACKET.values())
+BRACKETS = OPENING_BRACKETS | CLOSING_BRACKETS
+ALWAYS_NO_SPACE = CLOSING_BRACKETS | {token.COMMA, STANDALONE_COMMENT}
+
+
+class Visitor(Generic[T]):
+ """Basic lib2to3 visitor that yields things of type `T` on `visit()`."""
+
+ def visit(self, node: LN) -> Iterator[T]:
+ """Main method to visit `node` and its children.
+
+ It tries to find a `visit_*()` method for the given `node.type`, like
+ `visit_simple_stmt` for Node objects or `visit_INDENT` for Leaf objects.
+ If no dedicated `visit_*()` method is found, chooses `visit_default()`
+ instead.
+
+ Then yields objects of type `T` from the selected visitor.
+ """
+ if node.type < 256:
+ name = token.tok_name[node.type]
+ else:
+ name = str(type_repr(node.type))
+ # We explicitly branch on whether a visitor exists (instead of
+ # using self.visit_default as the default arg to getattr) in order
+ # to save needing to create a bound method object and so mypyc can
+ # generate a native call to visit_default.
+ visitf = getattr(self, f"visit_{name}", None)
+ if visitf:
+ yield from visitf(node)
+ else:
+ yield from self.visit_default(node)
+
+ def visit_default(self, node: LN) -> Iterator[T]:
+ """Default `visit_*()` implementation. Recurses to children of `node`."""
+ if isinstance(node, Node):
+ for child in node.children:
+ yield from self.visit(child)
+
+
+def whitespace(leaf: Leaf, *, complex_subscript: bool) -> str: # noqa: C901
+ """Return whitespace prefix if needed for the given `leaf`.
+
+ `complex_subscript` signals whether the given leaf is part of a subscription
+ which has non-trivial arguments, like arithmetic expressions or function calls.
+ """
+ NO = ""
+ SPACE = " "
+ DOUBLESPACE = " "
+ t = leaf.type
+ p = leaf.parent
+ v = leaf.value
+ if t in ALWAYS_NO_SPACE:
+ return NO
+
+ if t == token.COMMENT:
+ return DOUBLESPACE
+
+ assert p is not None, f"INTERNAL ERROR: hand-made leaf without parent: {leaf!r}"
+ if t == token.COLON and p.type not in {
+ syms.subscript,
+ syms.subscriptlist,
+ syms.sliceop,
+ }:
+ return NO
+
+ prev = leaf.prev_sibling
+ if not prev:
+ prevp = preceding_leaf(p)
+ if not prevp or prevp.type in OPENING_BRACKETS:
+ return NO
+
+ if t == token.COLON:
+ if prevp.type == token.COLON:
+ return NO
+
+ elif prevp.type != token.COMMA and not complex_subscript:
+ return NO
+
+ return SPACE
+
+ if prevp.type == token.EQUAL:
+ if prevp.parent:
+ if prevp.parent.type in {
+ syms.arglist,
+ syms.argument,
+ syms.parameters,
+ syms.varargslist,
+ }:
+ return NO
+
+ elif prevp.parent.type == syms.typedargslist:
+ # A bit hacky: if the equal sign has whitespace, it means we
+ # previously found it's a typed argument. So, we're using
+ # that, too.
+ return prevp.prefix
+
+ elif prevp.type in VARARGS_SPECIALS:
+ if is_vararg(prevp, within=VARARGS_PARENTS | UNPACKING_PARENTS):
+ return NO
+
+ elif prevp.type == token.COLON:
+ if prevp.parent and prevp.parent.type in {syms.subscript, syms.sliceop}:
+ return SPACE if complex_subscript else NO
+
+ elif (
+ prevp.parent
+ and prevp.parent.type == syms.factor
+ and prevp.type in MATH_OPERATORS
+ ):
+ return NO
+
+ elif (
+ prevp.type == token.RIGHTSHIFT
+ and prevp.parent
+ and prevp.parent.type == syms.shift_expr
+ and prevp.prev_sibling
+ and prevp.prev_sibling.type == token.NAME
+ and prevp.prev_sibling.value == "print" # type: ignore
+ ):
+ # Python 2 print chevron
+ return NO
+ elif prevp.type == token.AT and p.parent and p.parent.type == syms.decorator:
+ # no space in decorators
+ return NO
+
+ elif prev.type in OPENING_BRACKETS:
+ return NO
+
+ if p.type in {syms.parameters, syms.arglist}:
+ # untyped function signatures or calls
+ if not prev or prev.type != token.COMMA:
+ return NO
+
+ elif p.type == syms.varargslist:
+ # lambdas
+ if prev and prev.type != token.COMMA:
+ return NO
+
+ elif p.type == syms.typedargslist:
+ # typed function signatures
+ if not prev:
+ return NO
+
+ if t == token.EQUAL:
+ if prev.type != syms.tname:
+ return NO
+
+ elif prev.type == token.EQUAL:
+ # A bit hacky: if the equal sign has whitespace, it means we
+ # previously found it's a typed argument. So, we're using that, too.
+ return prev.prefix
+
+ elif prev.type != token.COMMA:
+ return NO
+
+ elif p.type == syms.tname:
+ # type names
+ if not prev:
+ prevp = preceding_leaf(p)
+ if not prevp or prevp.type != token.COMMA:
+ return NO
+
+ elif p.type == syms.trailer:
+ # attributes and calls
+ if t == token.LPAR or t == token.RPAR:
+ return NO
+
+ if not prev:
+ if t == token.DOT:
+ prevp = preceding_leaf(p)
+ if not prevp or prevp.type != token.NUMBER:
+ return NO
+
+ elif t == token.LSQB:
+ return NO
+
+ elif prev.type != token.COMMA:
+ return NO
+
+ elif p.type == syms.argument:
+ # single argument
+ if t == token.EQUAL:
+ return NO
+
+ if not prev:
+ prevp = preceding_leaf(p)
+ if not prevp or prevp.type == token.LPAR:
+ return NO
+
+ elif prev.type in {token.EQUAL} | VARARGS_SPECIALS:
+ return NO
+
+ elif p.type == syms.decorator:
+ # decorators
+ return NO
+
+ elif p.type == syms.dotted_name:
+ if prev:
+ return NO
+
+ prevp = preceding_leaf(p)
+ if not prevp or prevp.type == token.AT or prevp.type == token.DOT:
+ return NO
+
+ elif p.type == syms.classdef:
+ if t == token.LPAR:
+ return NO
+
+ if prev and prev.type == token.LPAR:
+ return NO
+
+ elif p.type in {syms.subscript, syms.sliceop}:
+ # indexing
+ if not prev:
+ assert p.parent is not None, "subscripts are always parented"
+ if p.parent.type == syms.subscriptlist:
+ return SPACE
+
+ return NO
+
+ elif not complex_subscript:
+ return NO
+
+ elif p.type == syms.atom:
+ if prev and t == token.DOT:
+ # dots, but not the first one.
+ return NO
+
+ elif p.type == syms.dictsetmaker:
+ # dict unpacking
+ if prev and prev.type == token.DOUBLESTAR:
+ return NO
+
+ elif p.type in {syms.factor, syms.star_expr}:
+ # unary ops
+ if not prev:
+ prevp = preceding_leaf(p)
+ if not prevp or prevp.type in OPENING_BRACKETS:
+ return NO
+
+ prevp_parent = prevp.parent
+ assert prevp_parent is not None
+ if prevp.type == token.COLON and prevp_parent.type in {
+ syms.subscript,
+ syms.sliceop,
+ }:
+ return NO
+
+ elif prevp.type == token.EQUAL and prevp_parent.type == syms.argument:
+ return NO
+
+ elif t in {token.NAME, token.NUMBER, token.STRING}:
+ return NO
+
+ elif p.type == syms.import_from:
+ if t == token.DOT:
+ if prev and prev.type == token.DOT:
+ return NO
+
+ elif t == token.NAME:
+ if v == "import":
+ return SPACE
+
+ if prev and prev.type == token.DOT:
+ return NO
+
+ elif p.type == syms.sliceop:
+ return NO
+
+ return SPACE
+
+
+def preceding_leaf(node: Optional[LN]) -> Optional[Leaf]:
+ """Return the first leaf that precedes `node`, if any."""
+ while node:
+ res = node.prev_sibling
+ if res:
+ if isinstance(res, Leaf):
+ return res
+
+ try:
+ return list(res.leaves())[-1]
+
+ except IndexError:
+ return None
+
+ node = node.parent
+ return None
+
+
+def prev_siblings_are(node: Optional[LN], tokens: List[Optional[NodeType]]) -> bool:
+ """Return if the `node` and its previous siblings match types against the provided
+ list of tokens; the provided `node`has its type matched against the last element in
+ the list. `None` can be used as the first element to declare that the start of the
+ list is anchored at the start of its parent's children."""
+ if not tokens:
+ return True
+ if tokens[-1] is None:
+ return node is None
+ if not node:
+ return False
+ if node.type != tokens[-1]:
+ return False
+ return prev_siblings_are(node.prev_sibling, tokens[:-1])
+
+
+def last_two_except(leaves: List[Leaf], omit: Collection[LeafID]) -> Tuple[Leaf, Leaf]:
+ """Return (penultimate, last) leaves skipping brackets in `omit` and contents."""
+ stop_after = None
+ last = None
+ for leaf in reversed(leaves):
+ if stop_after:
+ if leaf is stop_after:
+ stop_after = None
+ continue
+
+ if last:
+ return leaf, last
+
+ if id(leaf) in omit:
+ stop_after = leaf.opening_bracket
+ else:
+ last = leaf
+ else:
+ raise LookupError("Last two leaves were also skipped")
+
+
+def parent_type(node: Optional[LN]) -> Optional[NodeType]:
+ """
+ Returns:
+ @node.parent.type, if @node is not None and has a parent.
+ OR
+ None, otherwise.
+ """
+ if node is None or node.parent is None:
+ return None
+
+ return node.parent.type
+
+
+def child_towards(ancestor: Node, descendant: LN) -> Optional[LN]:
+ """Return the child of `ancestor` that contains `descendant`."""
+ node: Optional[LN] = descendant
+ while node and node.parent != ancestor:
+ node = node.parent
+ return node
+
+
+def replace_child(old_child: LN, new_child: LN) -> None:
+ """
+ Side Effects:
+ * If @old_child.parent is set, replace @old_child with @new_child in
+ @old_child's underlying Node structure.
+ OR
+ * Otherwise, this function does nothing.
+ """
+ parent = old_child.parent
+ if not parent:
+ return
+
+ child_idx = old_child.remove()
+ if child_idx is not None:
+ parent.insert_child(child_idx, new_child)
+
+
+def container_of(leaf: Leaf) -> LN:
+ """Return `leaf` or one of its ancestors that is the topmost container of it.
+
+ By "container" we mean a node where `leaf` is the very first child.
+ """
+ same_prefix = leaf.prefix
+ container: LN = leaf
+ while container:
+ parent = container.parent
+ if parent is None:
+ break
+
+ if parent.children[0].prefix != same_prefix:
+ break
+
+ if parent.type == syms.file_input:
+ break
+
+ if parent.prev_sibling is not None and parent.prev_sibling.type in BRACKETS:
+ break
+
+ container = parent
+ return container
+
+
+def first_leaf_column(node: Node) -> Optional[int]:
+ """Returns the column of the first leaf child of a node."""
+ for child in node.children:
+ if isinstance(child, Leaf):
+ return child.column
+ return None
+
+
+def first_child_is_arith(node: Node) -> bool:
+ """Whether first child is an arithmetic or a binary arithmetic expression"""
+ expr_types = {
+ syms.arith_expr,
+ syms.shift_expr,
+ syms.xor_expr,
+ syms.and_expr,
+ }
+ return bool(node.children and node.children[0].type in expr_types)
+
+
+def is_docstring(leaf: Leaf) -> bool:
+ if prev_siblings_are(
+ leaf.parent, [None, token.NEWLINE, token.INDENT, syms.simple_stmt]
+ ):
+ return True
+
+ # Multiline docstring on the same line as the `def`.
+ if prev_siblings_are(leaf.parent, [syms.parameters, token.COLON, syms.simple_stmt]):
+ # `syms.parameters` is only used in funcdefs and async_funcdefs in the Python
+ # grammar. We're safe to return True without further checks.
+ return True
+
+ return False
+
+
+def is_empty_tuple(node: LN) -> bool:
+ """Return True if `node` holds an empty tuple."""
+ return (
+ node.type == syms.atom
+ and len(node.children) == 2
+ and node.children[0].type == token.LPAR
+ and node.children[1].type == token.RPAR
+ )
+
+
+def is_one_tuple(node: LN) -> bool:
+ """Return True if `node` holds a tuple with one element, with or without parens."""
+ if node.type == syms.atom:
+ gexp = unwrap_singleton_parenthesis(node)
+ if gexp is None or gexp.type != syms.testlist_gexp:
+ return False
+
+ return len(gexp.children) == 2 and gexp.children[1].type == token.COMMA
+
+ return (
+ node.type in IMPLICIT_TUPLE
+ and len(node.children) == 2
+ and node.children[1].type == token.COMMA
+ )
+
+
+def is_one_tuple_between(opening: Leaf, closing: Leaf, leaves: List[Leaf]) -> bool:
+ """Return True if content between `opening` and `closing` looks like a one-tuple."""
+ if opening.type != token.LPAR and closing.type != token.RPAR:
+ return False
+
+ depth = closing.bracket_depth + 1
+ for _opening_index, leaf in enumerate(leaves):
+ if leaf is opening:
+ break
+
+ else:
+ raise LookupError("Opening paren not found in `leaves`")
+
+ commas = 0
+ _opening_index += 1
+ for leaf in leaves[_opening_index:]:
+ if leaf is closing:
+ break
+
+ bracket_depth = leaf.bracket_depth
+ if bracket_depth == depth and leaf.type == token.COMMA:
+ commas += 1
+ if leaf.parent and leaf.parent.type in {
+ syms.arglist,
+ syms.typedargslist,
+ }:
+ commas += 1
+ break
+
+ return commas < 2
+
+
+def is_walrus_assignment(node: LN) -> bool:
+ """Return True iff `node` is of the shape ( test := test )"""
+ inner = unwrap_singleton_parenthesis(node)
+ return inner is not None and inner.type == syms.namedexpr_test
+
+
+def is_simple_decorator_trailer(node: LN, last: bool = False) -> bool:
+ """Return True iff `node` is a trailer valid in a simple decorator"""
+ return node.type == syms.trailer and (
+ (
+ len(node.children) == 2
+ and node.children[0].type == token.DOT
+ and node.children[1].type == token.NAME
+ )
+ # last trailer can be an argument-less parentheses pair
+ or (
+ last
+ and len(node.children) == 2
+ and node.children[0].type == token.LPAR
+ and node.children[1].type == token.RPAR
+ )
+ # last trailer can be arguments
+ or (
+ last
+ and len(node.children) == 3
+ and node.children[0].type == token.LPAR
+ # and node.children[1].type == syms.argument
+ and node.children[2].type == token.RPAR
+ )
+ )
+
+
+def is_simple_decorator_expression(node: LN) -> bool:
+ """Return True iff `node` could be a 'dotted name' decorator
+
+ This function takes the node of the 'namedexpr_test' of the new decorator
+ grammar and test if it would be valid under the old decorator grammar.
+
+ The old grammar was: decorator: @ dotted_name [arguments] NEWLINE
+ The new grammar is : decorator: @ namedexpr_test NEWLINE
+ """
+ if node.type == token.NAME:
+ return True
+ if node.type == syms.power:
+ if node.children:
+ return (
+ node.children[0].type == token.NAME
+ and all(map(is_simple_decorator_trailer, node.children[1:-1]))
+ and (
+ len(node.children) < 2
+ or is_simple_decorator_trailer(node.children[-1], last=True)
+ )
+ )
+ return False
+
+
+def is_yield(node: LN) -> bool:
+ """Return True if `node` holds a `yield` or `yield from` expression."""
+ if node.type == syms.yield_expr:
+ return True
+
+ if node.type == token.NAME and node.value == "yield": # type: ignore
+ return True
+
+ if node.type != syms.atom:
+ return False
+
+ if len(node.children) != 3:
+ return False
+
+ lpar, expr, rpar = node.children
+ if lpar.type == token.LPAR and rpar.type == token.RPAR:
+ return is_yield(expr)
+
+ return False
+
+
+def is_vararg(leaf: Leaf, within: Set[NodeType]) -> bool:
+ """Return True if `leaf` is a star or double star in a vararg or kwarg.
+
+ If `within` includes VARARGS_PARENTS, this applies to function signatures.
+ If `within` includes UNPACKING_PARENTS, it applies to right hand-side
+ extended iterable unpacking (PEP 3132) and additional unpacking
+ generalizations (PEP 448).
+ """
+ if leaf.type not in VARARGS_SPECIALS or not leaf.parent:
+ return False
+
+ p = leaf.parent
+ if p.type == syms.star_expr:
+ # Star expressions are also used as assignment targets in extended
+ # iterable unpacking (PEP 3132). See what its parent is instead.
+ if not p.parent:
+ return False
+
+ p = p.parent
+
+ return p.type in within
+
+
+def is_multiline_string(leaf: Leaf) -> bool:
+ """Return True if `leaf` is a multiline string that actually spans many lines."""
+ return has_triple_quotes(leaf.value) and "\n" in leaf.value
+
+
+def is_stub_suite(node: Node) -> bool:
+ """Return True if `node` is a suite with a stub body."""
+ if (
+ len(node.children) != 4
+ or node.children[0].type != token.NEWLINE
+ or node.children[1].type != token.INDENT
+ or node.children[3].type != token.DEDENT
+ ):
+ return False
+
+ return is_stub_body(node.children[2])
+
+
+def is_stub_body(node: LN) -> bool:
+ """Return True if `node` is a simple statement containing an ellipsis."""
+ if not isinstance(node, Node) or node.type != syms.simple_stmt:
+ return False
+
+ if len(node.children) != 2:
+ return False
+
+ child = node.children[0]
+ return (
+ child.type == syms.atom
+ and len(child.children) == 3
+ and all(leaf == Leaf(token.DOT, ".") for leaf in child.children)
+ )
+
+
+def is_atom_with_invisible_parens(node: LN) -> bool:
+ """Given a `LN`, determines whether it's an atom `node` with invisible
+ parens. Useful in dedupe-ing and normalizing parens.
+ """
+ if isinstance(node, Leaf) or node.type != syms.atom:
+ return False
+
+ first, last = node.children[0], node.children[-1]
+ return (
+ isinstance(first, Leaf)
+ and first.type == token.LPAR
+ and first.value == ""
+ and isinstance(last, Leaf)
+ and last.type == token.RPAR
+ and last.value == ""
+ )
+
+
+def is_empty_par(leaf: Leaf) -> bool:
+ return is_empty_lpar(leaf) or is_empty_rpar(leaf)
+
+
+def is_empty_lpar(leaf: Leaf) -> bool:
+ return leaf.type == token.LPAR and leaf.value == ""
+
+
+def is_empty_rpar(leaf: Leaf) -> bool:
+ return leaf.type == token.RPAR and leaf.value == ""
+
+
+def is_import(leaf: Leaf) -> bool:
+ """Return True if the given leaf starts an import statement."""
+ p = leaf.parent
+ t = leaf.type
+ v = leaf.value
+ return bool(
+ t == token.NAME
+ and (
+ (v == "import" and p and p.type == syms.import_name)
+ or (v == "from" and p and p.type == syms.import_from)
+ )
+ )
+
+
+def is_type_comment(leaf: Leaf, suffix: str = "") -> bool:
+ """Return True if the given leaf is a special comment.
+ Only returns true for type comments for now."""
+ t = leaf.type
+ v = leaf.value
+ return t in {token.COMMENT, STANDALONE_COMMENT} and v.startswith("# type:" + suffix)
+
+
+def wrap_in_parentheses(parent: Node, child: LN, *, visible: bool = True) -> None:
+ """Wrap `child` in parentheses.
+
+ This replaces `child` with an atom holding the parentheses and the old
+ child. That requires moving the prefix.
+
+ If `visible` is False, the leaves will be valueless (and thus invisible).
+ """
+ lpar = Leaf(token.LPAR, "(" if visible else "")
+ rpar = Leaf(token.RPAR, ")" if visible else "")
+ prefix = child.prefix
+ child.prefix = ""
+ index = child.remove() or 0
+ new_child = Node(syms.atom, [lpar, child, rpar])
+ new_child.prefix = prefix
+ parent.insert_child(index, new_child)
+
+
+def unwrap_singleton_parenthesis(node: LN) -> Optional[LN]:
+ """Returns `wrapped` if `node` is of the shape ( wrapped ).
+
+ Parenthesis can be optional. Returns None otherwise"""
+ if len(node.children) != 3:
+ return None
+
+ lpar, wrapped, rpar = node.children
+ if not (lpar.type == token.LPAR and rpar.type == token.RPAR):
+ return None
+
+ return wrapped
+
+
+def ensure_visible(leaf: Leaf) -> None:
+ """Make sure parentheses are visible.
+
+ They could be invisible as part of some statements (see
+ :func:`normalize_invisible_parens` and :func:`visit_import_from`).
+ """
+ if leaf.type == token.LPAR:
+ leaf.value = "("
+ elif leaf.type == token.RPAR:
+ leaf.value = ")"
diff --git a/src/black/numerics.py b/src/black/numerics.py
new file mode 100644
index 0000000..cb1c83e
--- /dev/null
+++ b/src/black/numerics.py
@@ -0,0 +1,65 @@
+"""
+Formatting numeric literals.
+"""
+from blib2to3.pytree import Leaf
+
+
+def format_hex(text: str) -> str:
+ """
+ Formats a hexadecimal string like "0x12B3"
+ """
+ before, after = text[:2], text[2:]
+ return f"{before}{after.upper()}"
+
+
+def format_scientific_notation(text: str) -> str:
+ """Formats a numeric string utilizing scentific notation"""
+ before, after = text.split("e")
+ sign = ""
+ if after.startswith("-"):
+ after = after[1:]
+ sign = "-"
+ elif after.startswith("+"):
+ after = after[1:]
+ before = format_float_or_int_string(before)
+ return f"{before}e{sign}{after}"
+
+
+def format_long_or_complex_number(text: str) -> str:
+ """Formats a long or complex string like `10L` or `10j`"""
+ number = text[:-1]
+ suffix = text[-1]
+ # Capitalize in "2L" because "l" looks too similar to "1".
+ if suffix == "l":
+ suffix = "L"
+ return f"{format_float_or_int_string(number)}{suffix}"
+
+
+def format_float_or_int_string(text: str) -> str:
+ """Formats a float string like "1.0"."""
+ if "." not in text:
+ return text
+
+ before, after = text.split(".")
+ return f"{before or 0}.{after or 0}"
+
+
+def normalize_numeric_literal(leaf: Leaf) -> None:
+ """Normalizes numeric (float, int, and complex) literals.
+
+ All letters used in the representation are normalized to lowercase (except
+ in Python 2 long literals).
+ """
+ text = leaf.value.lower()
+ if text.startswith(("0o", "0b")):
+ # Leave octal and binary literals alone.
+ pass
+ elif text.startswith("0x"):
+ text = format_hex(text)
+ elif "e" in text:
+ text = format_scientific_notation(text)
+ elif text.endswith(("j", "l")):
+ text = format_long_or_complex_number(text)
+ else:
+ text = format_float_or_int_string(text)
+ leaf.value = text
diff --git a/src/black/output.py b/src/black/output.py
new file mode 100644
index 0000000..6831524
--- /dev/null
+++ b/src/black/output.py
@@ -0,0 +1,83 @@
+"""Nice output for Black.
+
+The double calls are for patching purposes in tests.
+"""
+
+from typing import Any, Optional
+from mypy_extensions import mypyc_attr
+import tempfile
+
+from click import echo, style
+
+
+def _out(message: Optional[str] = None, nl: bool = True, **styles: Any) -> None:
+ if message is not None:
+ if "bold" not in styles:
+ styles["bold"] = True
+ message = style(message, **styles)
+ echo(message, nl=nl, err=True)
+
+
+def _err(message: Optional[str] = None, nl: bool = True, **styles: Any) -> None:
+ if message is not None:
+ if "fg" not in styles:
+ styles["fg"] = "red"
+ message = style(message, **styles)
+ echo(message, nl=nl, err=True)
+
+
+def out(message: Optional[str] = None, nl: bool = True, **styles: Any) -> None:
+ _out(message, nl=nl, **styles)
+
+
+def err(message: Optional[str] = None, nl: bool = True, **styles: Any) -> None:
+ _err(message, nl=nl, **styles)
+
+
+def diff(a: str, b: str, a_name: str, b_name: str) -> str:
+ """Return a unified diff string between strings `a` and `b`."""
+ import difflib
+
+ a_lines = [line for line in a.splitlines(keepends=True)]
+ b_lines = [line for line in b.splitlines(keepends=True)]
+ diff_lines = []
+ for line in difflib.unified_diff(
+ a_lines, b_lines, fromfile=a_name, tofile=b_name, n=5
+ ):
+ # Work around https://bugs.python.org/issue2142
+ # See https://www.gnu.org/software/diffutils/manual/html_node/Incomplete-Lines.html
+ if line[-1] == "\n":
+ diff_lines.append(line)
+ else:
+ diff_lines.append(line + "\n")
+ diff_lines.append("\\ No newline at end of file\n")
+ return "".join(diff_lines)
+
+
+def color_diff(contents: str) -> str:
+ """Inject the ANSI color codes to the diff."""
+ lines = contents.split("\n")
+ for i, line in enumerate(lines):
+ if line.startswith("+++") or line.startswith("---"):
+ line = "\033[1;37m" + line + "\033[0m" # bold white, reset
+ elif line.startswith("@@"):
+ line = "\033[36m" + line + "\033[0m" # cyan, reset
+ elif line.startswith("+"):
+ line = "\033[32m" + line + "\033[0m" # green, reset
+ elif line.startswith("-"):
+ line = "\033[31m" + line + "\033[0m" # red, reset
+ lines[i] = line
+ return "\n".join(lines)
+
+
+@mypyc_attr(patchable=True)
+def dump_to_file(*output: str, ensure_final_newline: bool = True) -> str:
+ """Dump `output` to a temporary file. Return path to the file."""
+ with tempfile.NamedTemporaryFile(
+ mode="w", prefix="blk_", suffix=".log", delete=False, encoding="utf8"
+ ) as f:
+ for lines in output:
+ f.write(lines)
+ if ensure_final_newline and lines and lines[-1] != "\n":
+ f.write("\n")
+ return f.name
diff --git a/src/black/parsing.py b/src/black/parsing.py
new file mode 100644
index 0000000..8e9feea
--- /dev/null
+++ b/src/black/parsing.py
@@ -0,0 +1,215 @@
+"""
+Parse Python code and perform AST validation.
+"""
+import ast
+import sys
+from typing import Iterable, Iterator, List, Set, Union
+
+# lib2to3 fork
+from blib2to3.pytree import Node, Leaf
+from blib2to3 import pygram, pytree
+from blib2to3.pgen2 import driver
+from blib2to3.pgen2.grammar import Grammar
+from blib2to3.pgen2.parse import ParseError
+
+from black.mode import TargetVersion, Feature, supports_feature
+from black.nodes import syms
+
+try:
+ from typed_ast import ast3, ast27
+except ImportError:
+ if sys.version_info < (3, 8):
+ print(
+ "The typed_ast package is required but not installed.\n"
+ "You can upgrade to Python 3.8+ or install typed_ast with\n"
+ "`python3 -m pip install typed-ast`.",
+ file=sys.stderr,
+ )
+ sys.exit(1)
+ else:
+ ast3 = ast27 = ast
+
+
+class InvalidInput(ValueError):
+ """Raised when input source code fails all parse attempts."""
+
+
+def get_grammars(target_versions: Set[TargetVersion]) -> List[Grammar]:
+ if not target_versions:
+ # No target_version specified, so try all grammars.
+ return [
+ # Python 3.7+
+ pygram.python_grammar_no_print_statement_no_exec_statement_async_keywords,
+ # Python 3.0-3.6
+ pygram.python_grammar_no_print_statement_no_exec_statement,
+ # Python 2.7 with future print_function import
+ pygram.python_grammar_no_print_statement,
+ # Python 2.7
+ pygram.python_grammar,
+ ]
+
+ if all(version.is_python2() for version in target_versions):
+ # Python 2-only code, so try Python 2 grammars.
+ return [
+ # Python 2.7 with future print_function import
+ pygram.python_grammar_no_print_statement,
+ # Python 2.7
+ pygram.python_grammar,
+ ]
+
+ # Python 3-compatible code, so only try Python 3 grammar.
+ grammars = []
+ # If we have to parse both, try to parse async as a keyword first
+ if not supports_feature(target_versions, Feature.ASYNC_IDENTIFIERS):
+ # Python 3.7+
+ grammars.append(
+ pygram.python_grammar_no_print_statement_no_exec_statement_async_keywords
+ )
+ if not supports_feature(target_versions, Feature.ASYNC_KEYWORDS):
+ # Python 3.0-3.6
+ grammars.append(pygram.python_grammar_no_print_statement_no_exec_statement)
+ # At least one of the above branches must have been taken, because every Python
+ # version has exactly one of the two 'ASYNC_*' flags
+ return grammars
+
+
+def lib2to3_parse(src_txt: str, target_versions: Iterable[TargetVersion] = ()) -> Node:
+ """Given a string with source, return the lib2to3 Node."""
+ if not src_txt.endswith("\n"):
+ src_txt += "\n"
+
+ for grammar in get_grammars(set(target_versions)):
+ drv = driver.Driver(grammar, pytree.convert)
+ try:
+ result = drv.parse_string(src_txt, True)
+ break
+
+ except ParseError as pe:
+ lineno, column = pe.context[1]
+ lines = src_txt.splitlines()
+ try:
+ faulty_line = lines[lineno - 1]
+ except IndexError:
+ faulty_line = "<line number missing in source>"
+ exc = InvalidInput(f"Cannot parse: {lineno}:{column}: {faulty_line}")
+ else:
+ raise exc from None
+
+ if isinstance(result, Leaf):
+ result = Node(syms.file_input, [result])
+ return result
+
+
+def lib2to3_unparse(node: Node) -> str:
+ """Given a lib2to3 node, return its string representation."""
+ code = str(node)
+ return code
+
+
+def parse_ast(src: str) -> Union[ast.AST, ast3.AST, ast27.AST]:
+ filename = "<unknown>"
+ if sys.version_info >= (3, 8):
+ # TODO: support Python 4+ ;)
+ for minor_version in range(sys.version_info[1], 4, -1):
+ try:
+ return ast.parse(src, filename, feature_version=(3, minor_version))
+ except SyntaxError:
+ continue
+ else:
+ for feature_version in (7, 6):
+ try:
+ return ast3.parse(src, filename, feature_version=feature_version)
+ except SyntaxError:
+ continue
+ if ast27.__name__ == "ast":
+ raise SyntaxError(
+ "The requested source code has invalid Python 3 syntax.\n"
+ "If you are trying to format Python 2 files please reinstall Black"
+ " with the 'python2' extra: `python3 -m pip install black[python2]`."
+ )
+ return ast27.parse(src)
+
+
+def stringify_ast(
+ node: Union[ast.AST, ast3.AST, ast27.AST], depth: int = 0
+) -> Iterator[str]:
+ """Simple visitor generating strings to compare ASTs by content."""
+
+ node = fixup_ast_constants(node)
+
+ yield f"{' ' * depth}{node.__class__.__name__}("
+
+ for field in sorted(node._fields): # noqa: F402
+ # TypeIgnore has only one field 'lineno' which breaks this comparison
+ type_ignore_classes = (ast3.TypeIgnore, ast27.TypeIgnore)
+ if sys.version_info >= (3, 8):
+ type_ignore_classes += (ast.TypeIgnore,)
+ if isinstance(node, type_ignore_classes):
+ break
+
+ try:
+ value = getattr(node, field)
+ except AttributeError:
+ continue
+
+ yield f"{' ' * (depth+1)}{field}="
+
+ if isinstance(value, list):
+ for item in value:
+ # Ignore nested tuples within del statements, because we may insert
+ # parentheses and they change the AST.
+ if (
+ field == "targets"
+ and isinstance(node, (ast.Delete, ast3.Delete, ast27.Delete))
+ and isinstance(item, (ast.Tuple, ast3.Tuple, ast27.Tuple))
+ ):
+ for item in item.elts:
+ yield from stringify_ast(item, depth + 2)
+
+ elif isinstance(item, (ast.AST, ast3.AST, ast27.AST)):
+ yield from stringify_ast(item, depth + 2)
+
+ elif isinstance(value, (ast.AST, ast3.AST, ast27.AST)):
+ yield from stringify_ast(value, depth + 2)
+
+ else:
+ # Constant strings may be indented across newlines, if they are
+ # docstrings; fold spaces after newlines when comparing. Similarly,
+ # trailing and leading space may be removed.
+ # Note that when formatting Python 2 code, at least with Windows
+ # line-endings, docstrings can end up here as bytes instead of
+ # str so make sure that we handle both cases.
+ if (
+ isinstance(node, ast.Constant)
+ and field == "value"
+ and isinstance(value, (str, bytes))
+ ):
+ lineend = "\n" if isinstance(value, str) else b"\n"
+ # To normalize, we strip any leading and trailing space from
+ # each line...
+ stripped = [line.strip() for line in value.splitlines()]
+ normalized = lineend.join(stripped) # type: ignore[attr-defined]
+ # ...and remove any blank lines at the beginning and end of
+ # the whole string
+ normalized = normalized.strip()
+ else:
+ normalized = value
+ yield f"{' ' * (depth+2)}{normalized!r}, # {value.__class__.__name__}"
+
+ yield f"{' ' * depth}) # /{node.__class__.__name__}"
+
+
+def fixup_ast_constants(
+ node: Union[ast.AST, ast3.AST, ast27.AST]
+) -> Union[ast.AST, ast3.AST, ast27.AST]:
+ """Map ast nodes deprecated in 3.8 to Constant."""
+ if isinstance(node, (ast.Str, ast3.Str, ast27.Str, ast.Bytes, ast3.Bytes)):
+ return ast.Constant(value=node.s)
+
+ if isinstance(node, (ast.Num, ast3.Num, ast27.Num)):
+ return ast.Constant(value=node.n)
+
+ if isinstance(node, (ast.NameConstant, ast3.NameConstant)):
+ return ast.Constant(value=node.value)
+
+ return node
diff --git a/src/black/report.py b/src/black/report.py
new file mode 100644
index 0000000..8fc5da2
--- /dev/null
+++ b/src/black/report.py
@@ -0,0 +1,100 @@
+"""
+Summarize Black runs to users.
+"""
+from dataclasses import dataclass
+from enum import Enum
+from pathlib import Path
+
+from click import style
+
+from black.output import out, err
+
+
+class Changed(Enum):
+ NO = 0
+ CACHED = 1
+ YES = 2
+
+
+@dataclass
+class Report:
+ """Provides a reformatting counter. Can be rendered with `str(report)`."""
+
+ check: bool = False
+ diff: bool = False
+ quiet: bool = False
+ verbose: bool = False
+ change_count: int = 0
+ same_count: int = 0
+ failure_count: int = 0
+
+ def done(self, src: Path, changed: Changed) -> None:
+ """Increment the counter for successful reformatting. Write out a message."""
+ if changed is Changed.YES:
+ reformatted = "would reformat" if self.check or self.diff else "reformatted"
+ if self.verbose or not self.quiet:
+ out(f"{reformatted} {src}")
+ self.change_count += 1
+ else:
+ if self.verbose:
+ if changed is Changed.NO:
+ msg = f"{src} already well formatted, good job."
+ else:
+ msg = f"{src} wasn't modified on disk since last run."
+ out(msg, bold=False)
+ self.same_count += 1
+
+ def failed(self, src: Path, message: str) -> None:
+ """Increment the counter for failed reformatting. Write out a message."""
+ err(f"error: cannot format {src}: {message}")
+ self.failure_count += 1
+
+ def path_ignored(self, path: Path, message: str) -> None:
+ if self.verbose:
+ out(f"{path} ignored: {message}", bold=False)
+
+ @property
+ def return_code(self) -> int:
+ """Return the exit code that the app should use.
+
+ This considers the current state of changed files and failures:
+ - if there were any failures, return 123;
+ - if any files were changed and --check is being used, return 1;
+ - otherwise return 0.
+ """
+ # According to http://tldp.org/LDP/abs/html/exitcodes.html starting with
+ # 126 we have special return codes reserved by the shell.
+ if self.failure_count:
+ return 123
+
+ elif self.change_count and self.check:
+ return 1
+
+ return 0
+
+ def __str__(self) -> str:
+ """Render a color report of the current state.
+
+ Use `click.unstyle` to remove colors.
+ """
+ if self.check or self.diff:
+ reformatted = "would be reformatted"
+ unchanged = "would be left unchanged"
+ failed = "would fail to reformat"
+ else:
+ reformatted = "reformatted"
+ unchanged = "left unchanged"
+ failed = "failed to reformat"
+ report = []
+ if self.change_count:
+ s = "s" if self.change_count > 1 else ""
+ report.append(
+ style(f"{self.change_count} file{s} {reformatted}", bold=True)
+ )
+ if self.same_count:
+ s = "s" if self.same_count > 1 else ""
+ report.append(f"{self.same_count} file{s} {unchanged}")
+ if self.failure_count:
+ s = "s" if self.failure_count > 1 else ""
+ report.append(style(f"{self.failure_count} file{s} {failed}", fg="red"))
+ return ", ".join(report) + "."
diff --git a/src/black/rusty.py b/src/black/rusty.py
new file mode 100644
index 0000000..822e3d7
--- /dev/null
+++ b/src/black/rusty.py
@@ -0,0 +1,28 @@
+"""An error-handling model influenced by that used by the Rust programming language
+
+See https://doc.rust-lang.org/book/ch09-00-error-handling.html.
+"""
+from typing import Generic, TypeVar, Union
+
+
+T = TypeVar("T")
+E = TypeVar("E", bound=Exception)
+
+
+class Ok(Generic[T]):
+ def __init__(self, value: T) -> None:
+ self._value = value
+
+ def ok(self) -> T:
+ return self._value
+
+
+class Err(Generic[E]):
+ def __init__(self, e: E) -> None:
+ self._e = e
+
+ def err(self) -> E:
+ return self._e
+
+
+Result = Union[Ok[T], Err[E]]
diff --git a/src/black/strings.py b/src/black/strings.py
new file mode 100644
index 0000000..5b443dd
--- /dev/null
+++ b/src/black/strings.py
@@ -0,0 +1,216 @@
+"""
+Simple formatting on strings. Further string formatting code is in trans.py.
+"""
+
+import regex as re
+import sys
+from typing import List, Pattern
+
+
+STRING_PREFIX_CHARS = "furbFURB" # All possible string prefix characters.
+
+
+def sub_twice(regex: Pattern[str], replacement: str, original: str) -> str:
+ """Replace `regex` with `replacement` twice on `original`.
+
+ This is used by string normalization to perform replaces on
+ overlapping matches.
+ """
+ return regex.sub(replacement, regex.sub(replacement, original))
+
+
+def has_triple_quotes(string: str) -> bool:
+ """
+ Returns:
+ True iff @string starts with three quotation characters.
+ """
+ raw_string = string.lstrip(STRING_PREFIX_CHARS)
+ return raw_string[:3] in {'"""', "'''"}
+
+
+def lines_with_leading_tabs_expanded(s: str) -> List[str]:
+ """
+ Splits string into lines and expands only leading tabs (following the normal
+ Python rules)
+ """
+ lines = []
+ for line in s.splitlines():
+ # Find the index of the first non-whitespace character after a string of
+ # whitespace that includes at least one tab
+ match = re.match(r"\s*\t+\s*(\S)", line)
+ if match:
+ first_non_whitespace_idx = match.start(1)
+
+ lines.append(
+ line[:first_non_whitespace_idx].expandtabs()
+ + line[first_non_whitespace_idx:]
+ )
+ else:
+ lines.append(line)
+ return lines
+
+
+def fix_docstring(docstring: str, prefix: str) -> str:
+ # https://www.python.org/dev/peps/pep-0257/#handling-docstring-indentation
+ if not docstring:
+ return ""
+ lines = lines_with_leading_tabs_expanded(docstring)
+ # Determine minimum indentation (first line doesn't count):
+ indent = sys.maxsize
+ for line in lines[1:]:
+ stripped = line.lstrip()
+ if stripped:
+ indent = min(indent, len(line) - len(stripped))
+ # Remove indentation (first line is special):
+ trimmed = [lines[0].strip()]
+ if indent < sys.maxsize:
+ last_line_idx = len(lines) - 2
+ for i, line in enumerate(lines[1:]):
+ stripped_line = line[indent:].rstrip()
+ if stripped_line or i == last_line_idx:
+ trimmed.append(prefix + stripped_line)
+ else:
+ trimmed.append("")
+ return "\n".join(trimmed)
+
+
+def get_string_prefix(string: str) -> str:
+ """
+ Pre-conditions:
+ * assert_is_leaf_string(@string)
+
+ Returns:
+ @string's prefix (e.g. '', 'r', 'f', or 'rf').
+ """
+ assert_is_leaf_string(string)
+
+ prefix = ""
+ prefix_idx = 0
+ while string[prefix_idx] in STRING_PREFIX_CHARS:
+ prefix += string[prefix_idx].lower()
+ prefix_idx += 1
+
+ return prefix
+
+
+def assert_is_leaf_string(string: str) -> None:
+ """
+ Checks the pre-condition that @string has the format that you would expect
+ of `leaf.value` where `leaf` is some Leaf such that `leaf.type ==
+ token.STRING`. A more precise description of the pre-conditions that are
+ checked are listed below.
+
+ Pre-conditions:
+ * @string starts with either ', ", <prefix>', or <prefix>" where
+ `set(<prefix>)` is some subset of `set(STRING_PREFIX_CHARS)`.
+ * @string ends with a quote character (' or ").
+
+ Raises:
+ AssertionError(...) if the pre-conditions listed above are not
+ satisfied.
+ """
+ dquote_idx = string.find('"')
+ squote_idx = string.find("'")
+ if -1 in [dquote_idx, squote_idx]:
+ quote_idx = max(dquote_idx, squote_idx)
+ else:
+ quote_idx = min(squote_idx, dquote_idx)
+
+ assert (
+ 0 <= quote_idx < len(string) - 1
+ ), f"{string!r} is missing a starting quote character (' or \")."
+ assert string[-1] in (
+ "'",
+ '"',
+ ), f"{string!r} is missing an ending quote character (' or \")."
+ assert set(string[:quote_idx]).issubset(
+ set(STRING_PREFIX_CHARS)
+ ), f"{set(string[:quote_idx])} is NOT a subset of {set(STRING_PREFIX_CHARS)}."
+
+
+def normalize_string_prefix(s: str, remove_u_prefix: bool = False) -> str:
+ """Make all string prefixes lowercase.
+
+ If remove_u_prefix is given, also removes any u prefix from the string.
+ """
+ match = re.match(r"^([" + STRING_PREFIX_CHARS + r"]*)(.*)$", s, re.DOTALL)
+ assert match is not None, f"failed to match string {s!r}"
+ orig_prefix = match.group(1)
+ new_prefix = orig_prefix.replace("F", "f").replace("B", "b").replace("U", "u")
+ if remove_u_prefix:
+ new_prefix = new_prefix.replace("u", "")
+ return f"{new_prefix}{match.group(2)}"
+
+
+def normalize_string_quotes(s: str) -> str:
+ """Prefer double quotes but only if it doesn't cause more escaping.
+
+ Adds or removes backslashes as appropriate. Doesn't parse and fix
+ strings nested in f-strings.
+ """
+ value = s.lstrip(STRING_PREFIX_CHARS)
+ if value[:3] == '"""':
+ return s
+
+ elif value[:3] == "'''":
+ orig_quote = "'''"
+ new_quote = '"""'
+ elif value[0] == '"':
+ orig_quote = '"'
+ new_quote = "'"
+ else:
+ orig_quote = "'"
+ new_quote = '"'
+ first_quote_pos = s.find(orig_quote)
+ if first_quote_pos == -1:
+ return s # There's an internal error
+
+ prefix = s[:first_quote_pos]
+ unescaped_new_quote = re.compile(rf"(([^\\]|^)(\\\\)*){new_quote}")
+ escaped_new_quote = re.compile(rf"([^\\]|^)\\((?:\\\\)*){new_quote}")
+ escaped_orig_quote = re.compile(rf"([^\\]|^)\\((?:\\\\)*){orig_quote}")
+ body = s[first_quote_pos + len(orig_quote) : -len(orig_quote)]
+ if "r" in prefix.casefold():
+ if unescaped_new_quote.search(body):
+ # There's at least one unescaped new_quote in this raw string
+ # so converting is impossible
+ return s
+
+ # Do not introduce or remove backslashes in raw strings
+ new_body = body
+ else:
+ # remove unnecessary escapes
+ new_body = sub_twice(escaped_new_quote, rf"\1\2{new_quote}", body)
+ if body != new_body:
+ # Consider the string without unnecessary escapes as the original
+ body = new_body
+ s = f"{prefix}{orig_quote}{body}{orig_quote}"
+ new_body = sub_twice(escaped_orig_quote, rf"\1\2{orig_quote}", new_body)
+ new_body = sub_twice(unescaped_new_quote, rf"\1\\{new_quote}", new_body)
+ if "f" in prefix.casefold():
+ matches = re.findall(
+ r"""
+ (?:[^{]|^)\{ # start of the string or a non-{ followed by a single {
+ ([^{].*?) # contents of the brackets except if begins with {{
+ \}(?:[^}]|$) # A } followed by end of the string or a non-}
+ """,
+ new_body,
+ re.VERBOSE,
+ )
+ for m in matches:
+ if "\\" in str(m):
+ # Do not introduce backslashes in interpolated expressions
+ return s
+
+ if new_quote == '"""' and new_body[-1:] == '"':
+ # edge case:
+ new_body = new_body[:-1] + '\\"'
+ orig_escape_count = body.count("\\")
+ new_escape_count = new_body.count("\\")
+ if new_escape_count > orig_escape_count:
+ return s # Do not introduce more escaping
+
+ if new_escape_count == orig_escape_count and orig_quote == '"':
+ return s # Prefer double quotes
+
+ return f"{prefix}{new_quote}{new_body}{new_quote}"
diff --git a/src/black/trans.py b/src/black/trans.py
new file mode 100644
index 0000000..055f33c
--- /dev/null
+++ b/src/black/trans.py
@@ -0,0 +1,1925 @@
+"""
+String transformers that can split and merge strings.
+"""
+from abc import ABC, abstractmethod
+from collections import defaultdict
+from dataclasses import dataclass
+import regex as re
+from typing import (
+ Any,
+ Callable,
+ Collection,
+ Dict,
+ Iterable,
+ Iterator,
+ List,
+ Optional,
+ Sequence,
+ Tuple,
+ TypeVar,
+ Union,
+)
+
+from black.rusty import Result, Ok, Err
+
+from black.mode import Feature
+from black.nodes import syms, replace_child, parent_type
+from black.nodes import is_empty_par, is_empty_lpar, is_empty_rpar
+from black.nodes import CLOSING_BRACKETS, STANDALONE_COMMENT
+from black.lines import Line, append_leaves
+from black.brackets import BracketMatchError
+from black.comments import contains_pragma_comment
+from black.strings import has_triple_quotes, get_string_prefix, assert_is_leaf_string
+from black.strings import normalize_string_quotes
+
+from blib2to3.pytree import Leaf, Node
+from blib2to3.pgen2 import token
+
+
+class CannotTransform(Exception):
+ """Base class for errors raised by Transformers."""
+
+
+# types
+T = TypeVar("T")
+LN = Union[Leaf, Node]
+Transformer = Callable[[Line, Collection[Feature]], Iterator[Line]]
+Index = int
+NodeType = int
+ParserState = int
+StringID = int
+TResult = Result[T, CannotTransform] # (T)ransform Result
+TMatchResult = TResult[Index]
+
+
+def TErr(err_msg: str) -> Err[CannotTransform]:
+ """(T)ransform Err
+
+ Convenience function used when working with the TResult type.
+ """
+ cant_transform = CannotTransform(err_msg)
+ return Err(cant_transform)
+
+
+@dataclass # type: ignore
+class StringTransformer(ABC):
+ """
+ An implementation of the Transformer protocol that relies on its
+ subclasses overriding the template methods `do_match(...)` and
+ `do_transform(...)`.
+
+ This Transformer works exclusively on strings (for example, by merging
+ or splitting them).
+
+ The following sections can be found among the docstrings of each concrete
+ StringTransformer subclass.
+
+ Requirements:
+ Which requirements must be met of the given Line for this
+ StringTransformer to be applied?
+
+ Transformations:
+ If the given Line meets all of the above requirements, which string
+ transformations can you expect to be applied to it by this
+ StringTransformer?
+
+ Collaborations:
+ What contractual agreements does this StringTransformer have with other
+ StringTransfomers? Such collaborations should be eliminated/minimized
+ as much as possible.
+ """
+
+ line_length: int
+ normalize_strings: bool
+ __name__ = "StringTransformer"
+
+ @abstractmethod
+ def do_match(self, line: Line) -> TMatchResult:
+ """
+ Returns:
+ * Ok(string_idx) such that `line.leaves[string_idx]` is our target
+ string, if a match was able to be made.
+ OR
+ * Err(CannotTransform), if a match was not able to be made.
+ """
+
+ @abstractmethod
+ def do_transform(self, line: Line, string_idx: int) -> Iterator[TResult[Line]]:
+ """
+ Yields:
+ * Ok(new_line) where new_line is the new transformed line.
+ OR
+ * Err(CannotTransform) if the transformation failed for some reason. The
+ `do_match(...)` template method should usually be used to reject
+ the form of the given Line, but in some cases it is difficult to
+ know whether or not a Line meets the StringTransformer's
+ requirements until the transformation is already midway.
+
+ Side Effects:
+ This method should NOT mutate @line directly, but it MAY mutate the
+ Line's underlying Node structure. (WARNING: If the underlying Node
+ structure IS altered, then this method should NOT be allowed to
+ yield an CannotTransform after that point.)
+ """
+
+ def __call__(self, line: Line, _features: Collection[Feature]) -> Iterator[Line]:
+ """
+ StringTransformer instances have a call signature that mirrors that of
+ the Transformer type.
+
+ Raises:
+ CannotTransform(...) if the concrete StringTransformer class is unable
+ to transform @line.
+ """
+ # Optimization to avoid calling `self.do_match(...)` when the line does
+ # not contain any string.
+ if not any(leaf.type == token.STRING for leaf in line.leaves):
+ raise CannotTransform("There are no strings in this line.")
+
+ match_result = self.do_match(line)
+
+ if isinstance(match_result, Err):
+ cant_transform = match_result.err()
+ raise CannotTransform(
+ f"The string transformer {self.__class__.__name__} does not recognize"
+ " this line as one that it can transform."
+ ) from cant_transform
+
+ string_idx = match_result.ok()
+
+ for line_result in self.do_transform(line, string_idx):
+ if isinstance(line_result, Err):
+ cant_transform = line_result.err()
+ raise CannotTransform(
+ "StringTransformer failed while attempting to transform string."
+ ) from cant_transform
+ line = line_result.ok()
+ yield line
+
+
+@dataclass
+class CustomSplit:
+ """A custom (i.e. manual) string split.
+
+ A single CustomSplit instance represents a single substring.
+
+ Examples:
+ Consider the following string:
+ ```
+ "Hi there friend."
+ " This is a custom"
+ f" string {split}."
+ ```
+
+ This string will correspond to the following three CustomSplit instances:
+ ```
+ CustomSplit(False, 16)
+ CustomSplit(False, 17)
+ CustomSplit(True, 16)
+ ```
+ """
+
+ has_prefix: bool
+ break_idx: int
+
+
+class CustomSplitMapMixin:
+ """
+ This mixin class is used to map merged strings to a sequence of
+ CustomSplits, which will then be used to re-split the strings iff none of
+ the resultant substrings go over the configured max line length.
+ """
+
+ _Key = Tuple[StringID, str]
+ _CUSTOM_SPLIT_MAP: Dict[_Key, Tuple[CustomSplit, ...]] = defaultdict(tuple)
+
+ @staticmethod
+ def _get_key(string: str) -> "CustomSplitMapMixin._Key":
+ """
+ Returns:
+ A unique identifier that is used internally to map @string to a
+ group of custom splits.
+ """
+ return (id(string), string)
+
+ def add_custom_splits(
+ self, string: str, custom_splits: Iterable[CustomSplit]
+ ) -> None:
+ """Custom Split Map Setter Method
+
+ Side Effects:
+ Adds a mapping from @string to the custom splits @custom_splits.
+ """
+ key = self._get_key(string)
+ self._CUSTOM_SPLIT_MAP[key] = tuple(custom_splits)
+
+ def pop_custom_splits(self, string: str) -> List[CustomSplit]:
+ """Custom Split Map Getter Method
+
+ Returns:
+ * A list of the custom splits that are mapped to @string, if any
+ exist.
+ OR
+ * [], otherwise.
+
+ Side Effects:
+ Deletes the mapping between @string and its associated custom
+ splits (which are returned to the caller).
+ """
+ key = self._get_key(string)
+
+ custom_splits = self._CUSTOM_SPLIT_MAP[key]
+ del self._CUSTOM_SPLIT_MAP[key]
+
+ return list(custom_splits)
+
+ def has_custom_splits(self, string: str) -> bool:
+ """
+ Returns:
+ True iff @string is associated with a set of custom splits.
+ """
+ key = self._get_key(string)
+ return key in self._CUSTOM_SPLIT_MAP
+
+
+class StringMerger(CustomSplitMapMixin, StringTransformer):
+ """StringTransformer that merges strings together.
+
+ Requirements:
+ (A) The line contains adjacent strings such that ALL of the validation checks
+ listed in StringMerger.__validate_msg(...)'s docstring pass.
+ OR
+ (B) The line contains a string which uses line continuation backslashes.
+
+ Transformations:
+ Depending on which of the two requirements above where met, either:
+
+ (A) The string group associated with the target string is merged.
+ OR
+ (B) All line-continuation backslashes are removed from the target string.
+
+ Collaborations:
+ StringMerger provides custom split information to StringSplitter.
+ """
+
+ def do_match(self, line: Line) -> TMatchResult:
+ LL = line.leaves
+
+ is_valid_index = is_valid_index_factory(LL)
+
+ for (i, leaf) in enumerate(LL):
+ if (
+ leaf.type == token.STRING
+ and is_valid_index(i + 1)
+ and LL[i + 1].type == token.STRING
+ ):
+ return Ok(i)
+
+ if leaf.type == token.STRING and "\\\n" in leaf.value:
+ return Ok(i)
+
+ return TErr("This line has no strings that need merging.")
+
+ def do_transform(self, line: Line, string_idx: int) -> Iterator[TResult[Line]]:
+ new_line = line
+ rblc_result = self._remove_backslash_line_continuation_chars(
+ new_line, string_idx
+ )
+ if isinstance(rblc_result, Ok):
+ new_line = rblc_result.ok()
+
+ msg_result = self._merge_string_group(new_line, string_idx)
+ if isinstance(msg_result, Ok):
+ new_line = msg_result.ok()
+
+ if isinstance(rblc_result, Err) and isinstance(msg_result, Err):
+ msg_cant_transform = msg_result.err()
+ rblc_cant_transform = rblc_result.err()
+ cant_transform = CannotTransform(
+ "StringMerger failed to merge any strings in this line."
+ )
+
+ # Chain the errors together using `__cause__`.
+ msg_cant_transform.__cause__ = rblc_cant_transform
+ cant_transform.__cause__ = msg_cant_transform
+
+ yield Err(cant_transform)
+ else:
+ yield Ok(new_line)
+
+ @staticmethod
+ def _remove_backslash_line_continuation_chars(
+ line: Line, string_idx: int
+ ) -> TResult[Line]:
+ """
+ Merge strings that were split across multiple lines using
+ line-continuation backslashes.
+
+ Returns:
+ Ok(new_line), if @line contains backslash line-continuation
+ characters.
+ OR
+ Err(CannotTransform), otherwise.
+ """
+ LL = line.leaves
+
+ string_leaf = LL[string_idx]
+ if not (
+ string_leaf.type == token.STRING
+ and "\\\n" in string_leaf.value
+ and not has_triple_quotes(string_leaf.value)
+ ):
+ return TErr(
+ f"String leaf {string_leaf} does not contain any backslash line"
+ " continuation characters."
+ )
+
+ new_line = line.clone()
+ new_line.comments = line.comments.copy()
+ append_leaves(new_line, line, LL)
+
+ new_string_leaf = new_line.leaves[string_idx]
+ new_string_leaf.value = new_string_leaf.value.replace("\\\n", "")
+
+ return Ok(new_line)
+
+ def _merge_string_group(self, line: Line, string_idx: int) -> TResult[Line]:
+ """
+ Merges string group (i.e. set of adjacent strings) where the first
+ string in the group is `line.leaves[string_idx]`.
+
+ Returns:
+ Ok(new_line), if ALL of the validation checks found in
+ __validate_msg(...) pass.
+ OR
+ Err(CannotTransform), otherwise.
+ """
+ LL = line.leaves
+
+ is_valid_index = is_valid_index_factory(LL)
+
+ vresult = self._validate_msg(line, string_idx)
+ if isinstance(vresult, Err):
+ return vresult
+
+ # If the string group is wrapped inside an Atom node, we must make sure
+ # to later replace that Atom with our new (merged) string leaf.
+ atom_node = LL[string_idx].parent
+
+ # We will place BREAK_MARK in between every two substrings that we
+ # merge. We will then later go through our final result and use the
+ # various instances of BREAK_MARK we find to add the right values to
+ # the custom split map.
+ BREAK_MARK = "@@@@@ BLACK BREAKPOINT MARKER @@@@@"
+
+ QUOTE = LL[string_idx].value[-1]
+
+ def make_naked(string: str, string_prefix: str) -> str:
+ """Strip @string (i.e. make it a "naked" string)
+
+ Pre-conditions:
+ * assert_is_leaf_string(@string)
+
+ Returns:
+ A string that is identical to @string except that
+ @string_prefix has been stripped, the surrounding QUOTE
+ characters have been removed, and any remaining QUOTE
+ characters have been escaped.
+ """
+ assert_is_leaf_string(string)
+
+ RE_EVEN_BACKSLASHES = r"(?:(?<!\\)(?:\\\\)*)"
+ naked_string = string[len(string_prefix) + 1 : -1]
+ naked_string = re.sub(
+ "(" + RE_EVEN_BACKSLASHES + ")" + QUOTE, r"\1\\" + QUOTE, naked_string
+ )
+ return naked_string
+
+ # Holds the CustomSplit objects that will later be added to the custom
+ # split map.
+ custom_splits = []
+
+ # Temporary storage for the 'has_prefix' part of the CustomSplit objects.
+ prefix_tracker = []
+
+ # Sets the 'prefix' variable. This is the prefix that the final merged
+ # string will have.
+ next_str_idx = string_idx
+ prefix = ""
+ while (
+ not prefix
+ and is_valid_index(next_str_idx)
+ and LL[next_str_idx].type == token.STRING
+ ):
+ prefix = get_string_prefix(LL[next_str_idx].value)
+ next_str_idx += 1
+
+ # The next loop merges the string group. The final string will be
+ # contained in 'S'.
+ #
+ # The following convenience variables are used:
+ #
+ # S: string
+ # NS: naked string
+ # SS: next string
+ # NSS: naked next string
+ S = ""
+ NS = ""
+ num_of_strings = 0
+ next_str_idx = string_idx
+ while is_valid_index(next_str_idx) and LL[next_str_idx].type == token.STRING:
+ num_of_strings += 1
+
+ SS = LL[next_str_idx].value
+ next_prefix = get_string_prefix(SS)
+
+ # If this is an f-string group but this substring is not prefixed
+ # with 'f'...
+ if "f" in prefix and "f" not in next_prefix:
+ # Then we must escape any braces contained in this substring.
+ SS = re.subf(r"(\{|\})", "{1}{1}", SS)
+
+ NSS = make_naked(SS, next_prefix)
+
+ has_prefix = bool(next_prefix)
+ prefix_tracker.append(has_prefix)
+
+ S = prefix + QUOTE + NS + NSS + BREAK_MARK + QUOTE
+ NS = make_naked(S, prefix)
+
+ next_str_idx += 1
+
+ S_leaf = Leaf(token.STRING, S)
+ if self.normalize_strings:
+ S_leaf.value = normalize_string_quotes(S_leaf.value)
+
+ # Fill the 'custom_splits' list with the appropriate CustomSplit objects.
+ temp_string = S_leaf.value[len(prefix) + 1 : -1]
+ for has_prefix in prefix_tracker:
+ mark_idx = temp_string.find(BREAK_MARK)
+ assert (
+ mark_idx >= 0
+ ), "Logic error while filling the custom string breakpoint cache."
+
+ temp_string = temp_string[mark_idx + len(BREAK_MARK) :]
+ breakpoint_idx = mark_idx + (len(prefix) if has_prefix else 0) + 1
+ custom_splits.append(CustomSplit(has_prefix, breakpoint_idx))
+
+ string_leaf = Leaf(token.STRING, S_leaf.value.replace(BREAK_MARK, ""))
+
+ if atom_node is not None:
+ replace_child(atom_node, string_leaf)
+
+ # Build the final line ('new_line') that this method will later return.
+ new_line = line.clone()
+ for (i, leaf) in enumerate(LL):
+ if i == string_idx:
+ new_line.append(string_leaf)
+
+ if string_idx <= i < string_idx + num_of_strings:
+ for comment_leaf in line.comments_after(LL[i]):
+ new_line.append(comment_leaf, preformatted=True)
+ continue
+
+ append_leaves(new_line, line, [leaf])
+
+ self.add_custom_splits(string_leaf.value, custom_splits)
+ return Ok(new_line)
+
+ @staticmethod
+ def _validate_msg(line: Line, string_idx: int) -> TResult[None]:
+ """Validate (M)erge (S)tring (G)roup
+
+ Transform-time string validation logic for __merge_string_group(...).
+
+ Returns:
+ * Ok(None), if ALL validation checks (listed below) pass.
+ OR
+ * Err(CannotTransform), if any of the following are true:
+ - The target string group does not contain ANY stand-alone comments.
+ - The target string is not in a string group (i.e. it has no
+ adjacent strings).
+ - The string group has more than one inline comment.
+ - The string group has an inline comment that appears to be a pragma.
+ - The set of all string prefixes in the string group is of
+ length greater than one and is not equal to {"", "f"}.
+ - The string group consists of raw strings.
+ """
+ # We first check for "inner" stand-alone comments (i.e. stand-alone
+ # comments that have a string leaf before them AND after them).
+ for inc in [1, -1]:
+ i = string_idx
+ found_sa_comment = False
+ is_valid_index = is_valid_index_factory(line.leaves)
+ while is_valid_index(i) and line.leaves[i].type in [
+ token.STRING,
+ STANDALONE_COMMENT,
+ ]:
+ if line.leaves[i].type == STANDALONE_COMMENT:
+ found_sa_comment = True
+ elif found_sa_comment:
+ return TErr(
+ "StringMerger does NOT merge string groups which contain "
+ "stand-alone comments."
+ )
+
+ i += inc
+
+ num_of_inline_string_comments = 0
+ set_of_prefixes = set()
+ num_of_strings = 0
+ for leaf in line.leaves[string_idx:]:
+ if leaf.type != token.STRING:
+ # If the string group is trailed by a comma, we count the
+ # comments trailing the comma to be one of the string group's
+ # comments.
+ if leaf.type == token.COMMA and id(leaf) in line.comments:
+ num_of_inline_string_comments += 1
+ break
+
+ if has_triple_quotes(leaf.value):
+ return TErr("StringMerger does NOT merge multiline strings.")
+
+ num_of_strings += 1
+ prefix = get_string_prefix(leaf.value)
+ if "r" in prefix:
+ return TErr("StringMerger does NOT merge raw strings.")
+
+ set_of_prefixes.add(prefix)
+
+ if id(leaf) in line.comments:
+ num_of_inline_string_comments += 1
+ if contains_pragma_comment(line.comments[id(leaf)]):
+ return TErr("Cannot merge strings which have pragma comments.")
+
+ if num_of_strings < 2:
+ return TErr(
+ f"Not enough strings to merge (num_of_strings={num_of_strings})."
+ )
+
+ if num_of_inline_string_comments > 1:
+ return TErr(
+ f"Too many inline string comments ({num_of_inline_string_comments})."
+ )
+
+ if len(set_of_prefixes) > 1 and set_of_prefixes != {"", "f"}:
+ return TErr(f"Too many different prefixes ({set_of_prefixes}).")
+
+ return Ok(None)
+
+
+class StringParenStripper(StringTransformer):
+ """StringTransformer that strips surrounding parentheses from strings.
+
+ Requirements:
+ The line contains a string which is surrounded by parentheses and:
+ - The target string is NOT the only argument to a function call.
+ - The target string is NOT a "pointless" string.
+ - If the target string contains a PERCENT, the brackets are not
+ preceeded or followed by an operator with higher precedence than
+ PERCENT.
+
+ Transformations:
+ The parentheses mentioned in the 'Requirements' section are stripped.
+
+ Collaborations:
+ StringParenStripper has its own inherent usefulness, but it is also
+ relied on to clean up the parentheses created by StringParenWrapper (in
+ the event that they are no longer needed).
+ """
+
+ def do_match(self, line: Line) -> TMatchResult:
+ LL = line.leaves
+
+ is_valid_index = is_valid_index_factory(LL)
+
+ for (idx, leaf) in enumerate(LL):
+ # Should be a string...
+ if leaf.type != token.STRING:
+ continue
+
+ # If this is a "pointless" string...
+ if (
+ leaf.parent
+ and leaf.parent.parent
+ and leaf.parent.parent.type == syms.simple_stmt
+ ):
+ continue
+
+ # Should be preceded by a non-empty LPAR...
+ if (
+ not is_valid_index(idx - 1)
+ or LL[idx - 1].type != token.LPAR
+ or is_empty_lpar(LL[idx - 1])
+ ):
+ continue
+
+ # That LPAR should NOT be preceded by a function name or a closing
+ # bracket (which could be a function which returns a function or a
+ # list/dictionary that contains a function)...
+ if is_valid_index(idx - 2) and (
+ LL[idx - 2].type == token.NAME or LL[idx - 2].type in CLOSING_BRACKETS
+ ):
+ continue
+
+ string_idx = idx
+
+ # Skip the string trailer, if one exists.
+ string_parser = StringParser()
+ next_idx = string_parser.parse(LL, string_idx)
+
+ # if the leaves in the parsed string include a PERCENT, we need to
+ # make sure the initial LPAR is NOT preceded by an operator with
+ # higher or equal precedence to PERCENT
+ if is_valid_index(idx - 2):
+ # mypy can't quite follow unless we name this
+ before_lpar = LL[idx - 2]
+ if token.PERCENT in {leaf.type for leaf in LL[idx - 1 : next_idx]} and (
+ (
+ before_lpar.type
+ in {
+ token.STAR,
+ token.AT,
+ token.SLASH,
+ token.DOUBLESLASH,
+ token.PERCENT,
+ token.TILDE,
+ token.DOUBLESTAR,
+ token.AWAIT,
+ token.LSQB,
+ token.LPAR,
+ }
+ )
+ or (
+ # only unary PLUS/MINUS
+ before_lpar.parent
+ and before_lpar.parent.type == syms.factor
+ and (before_lpar.type in {token.PLUS, token.MINUS})
+ )
+ ):
+ continue
+
+ # Should be followed by a non-empty RPAR...
+ if (
+ is_valid_index(next_idx)
+ and LL[next_idx].type == token.RPAR
+ and not is_empty_rpar(LL[next_idx])
+ ):
+ # That RPAR should NOT be followed by anything with higher
+ # precedence than PERCENT
+ if is_valid_index(next_idx + 1) and LL[next_idx + 1].type in {
+ token.DOUBLESTAR,
+ token.LSQB,
+ token.LPAR,
+ token.DOT,
+ }:
+ continue
+
+ return Ok(string_idx)
+
+ return TErr("This line has no strings wrapped in parens.")
+
+ def do_transform(self, line: Line, string_idx: int) -> Iterator[TResult[Line]]:
+ LL = line.leaves
+
+ string_parser = StringParser()
+ rpar_idx = string_parser.parse(LL, string_idx)
+
+ for leaf in (LL[string_idx - 1], LL[rpar_idx]):
+ if line.comments_after(leaf):
+ yield TErr(
+ "Will not strip parentheses which have comments attached to them."
+ )
+ return
+
+ new_line = line.clone()
+ new_line.comments = line.comments.copy()
+ try:
+ append_leaves(new_line, line, LL[: string_idx - 1])
+ except BracketMatchError:
+ # HACK: I believe there is currently a bug somewhere in
+ # right_hand_split() that is causing brackets to not be tracked
+ # properly by a shared BracketTracker.
+ append_leaves(new_line, line, LL[: string_idx - 1], preformatted=True)
+
+ string_leaf = Leaf(token.STRING, LL[string_idx].value)
+ LL[string_idx - 1].remove()
+ replace_child(LL[string_idx], string_leaf)
+ new_line.append(string_leaf)
+
+ append_leaves(
+ new_line, line, LL[string_idx + 1 : rpar_idx] + LL[rpar_idx + 1 :]
+ )
+
+ LL[rpar_idx].remove()
+
+ yield Ok(new_line)
+
+
+class BaseStringSplitter(StringTransformer):
+ """
+ Abstract class for StringTransformers which transform a Line's strings by splitting
+ them or placing them on their own lines where necessary to avoid going over
+ the configured line length.
+
+ Requirements:
+ * The target string value is responsible for the line going over the
+ line length limit. It follows that after all of black's other line
+ split methods have been exhausted, this line (or one of the resulting
+ lines after all line splits are performed) would still be over the
+ line_length limit unless we split this string.
+ AND
+ * The target string is NOT a "pointless" string (i.e. a string that has
+ no parent or siblings).
+ AND
+ * The target string is not followed by an inline comment that appears
+ to be a pragma.
+ AND
+ * The target string is not a multiline (i.e. triple-quote) string.
+ """
+
+ @abstractmethod
+ def do_splitter_match(self, line: Line) -> TMatchResult:
+ """
+ BaseStringSplitter asks its clients to override this method instead of
+ `StringTransformer.do_match(...)`.
+
+ Follows the same protocol as `StringTransformer.do_match(...)`.
+
+ Refer to `help(StringTransformer.do_match)` for more information.
+ """
+
+ def do_match(self, line: Line) -> TMatchResult:
+ match_result = self.do_splitter_match(line)
+ if isinstance(match_result, Err):
+ return match_result
+
+ string_idx = match_result.ok()
+ vresult = self._validate(line, string_idx)
+ if isinstance(vresult, Err):
+ return vresult
+
+ return match_result
+
+ def _validate(self, line: Line, string_idx: int) -> TResult[None]:
+ """
+ Checks that @line meets all of the requirements listed in this classes'
+ docstring. Refer to `help(BaseStringSplitter)` for a detailed
+ description of those requirements.
+
+ Returns:
+ * Ok(None), if ALL of the requirements are met.
+ OR
+ * Err(CannotTransform), if ANY of the requirements are NOT met.
+ """
+ LL = line.leaves
+
+ string_leaf = LL[string_idx]
+
+ max_string_length = self._get_max_string_length(line, string_idx)
+ if len(string_leaf.value) <= max_string_length:
+ return TErr(
+ "The string itself is not what is causing this line to be too long."
+ )
+
+ if not string_leaf.parent or [L.type for L in string_leaf.parent.children] == [
+ token.STRING,
+ token.NEWLINE,
+ ]:
+ return TErr(
+ f"This string ({string_leaf.value}) appears to be pointless (i.e. has"
+ " no parent)."
+ )
+
+ if id(line.leaves[string_idx]) in line.comments and contains_pragma_comment(
+ line.comments[id(line.leaves[string_idx])]
+ ):
+ return TErr(
+ "Line appears to end with an inline pragma comment. Splitting the line"
+ " could modify the pragma's behavior."
+ )
+
+ if has_triple_quotes(string_leaf.value):
+ return TErr("We cannot split multiline strings.")
+
+ return Ok(None)
+
+ def _get_max_string_length(self, line: Line, string_idx: int) -> int:
+ """
+ Calculates the max string length used when attempting to determine
+ whether or not the target string is responsible for causing the line to
+ go over the line length limit.
+
+ WARNING: This method is tightly coupled to both StringSplitter and
+ (especially) StringParenWrapper. There is probably a better way to
+ accomplish what is being done here.
+
+ Returns:
+ max_string_length: such that `line.leaves[string_idx].value >
+ max_string_length` implies that the target string IS responsible
+ for causing this line to exceed the line length limit.
+ """
+ LL = line.leaves
+
+ is_valid_index = is_valid_index_factory(LL)
+
+ # We use the shorthand "WMA4" in comments to abbreviate "We must
+ # account for". When giving examples, we use STRING to mean some/any
+ # valid string.
+ #
+ # Finally, we use the following convenience variables:
+ #
+ # P: The leaf that is before the target string leaf.
+ # N: The leaf that is after the target string leaf.
+ # NN: The leaf that is after N.
+
+ # WMA4 the whitespace at the beginning of the line.
+ offset = line.depth * 4
+
+ if is_valid_index(string_idx - 1):
+ p_idx = string_idx - 1
+ if (
+ LL[string_idx - 1].type == token.LPAR
+ and LL[string_idx - 1].value == ""
+ and string_idx >= 2
+ ):
+ # If the previous leaf is an empty LPAR placeholder, we should skip it.
+ p_idx -= 1
+
+ P = LL[p_idx]
+ if P.type == token.PLUS:
+ # WMA4 a space and a '+' character (e.g. `+ STRING`).
+ offset += 2
+
+ if P.type == token.COMMA:
+ # WMA4 a space, a comma, and a closing bracket [e.g. `), STRING`].
+ offset += 3
+
+ if P.type in [token.COLON, token.EQUAL, token.NAME]:
+ # This conditional branch is meant to handle dictionary keys,
+ # variable assignments, 'return STRING' statement lines, and
+ # 'else STRING' ternary expression lines.
+
+ # WMA4 a single space.
+ offset += 1
+
+ # WMA4 the lengths of any leaves that came before that space,
+ # but after any closing bracket before that space.
+ for leaf in reversed(LL[: p_idx + 1]):
+ offset += len(str(leaf))
+ if leaf.type in CLOSING_BRACKETS:
+ break
+
+ if is_valid_index(string_idx + 1):
+ N = LL[string_idx + 1]
+ if N.type == token.RPAR and N.value == "" and len(LL) > string_idx + 2:
+ # If the next leaf is an empty RPAR placeholder, we should skip it.
+ N = LL[string_idx + 2]
+
+ if N.type == token.COMMA:
+ # WMA4 a single comma at the end of the string (e.g `STRING,`).
+ offset += 1
+
+ if is_valid_index(string_idx + 2):
+ NN = LL[string_idx + 2]
+
+ if N.type == token.DOT and NN.type == token.NAME:
+ # This conditional branch is meant to handle method calls invoked
+ # off of a string literal up to and including the LPAR character.
+
+ # WMA4 the '.' character.
+ offset += 1
+
+ if (
+ is_valid_index(string_idx + 3)
+ and LL[string_idx + 3].type == token.LPAR
+ ):
+ # WMA4 the left parenthesis character.
+ offset += 1
+
+ # WMA4 the length of the method's name.
+ offset += len(NN.value)
+
+ has_comments = False
+ for comment_leaf in line.comments_after(LL[string_idx]):
+ if not has_comments:
+ has_comments = True
+ # WMA4 two spaces before the '#' character.
+ offset += 2
+
+ # WMA4 the length of the inline comment.
+ offset += len(comment_leaf.value)
+
+ max_string_length = self.line_length - offset
+ return max_string_length
+
+
+class StringSplitter(CustomSplitMapMixin, BaseStringSplitter):
+ """
+ StringTransformer that splits "atom" strings (i.e. strings which exist on
+ lines by themselves).
+
+ Requirements:
+ * The line consists ONLY of a single string (with the exception of a
+ '+' symbol which MAY exist at the start of the line), MAYBE a string
+ trailer, and MAYBE a trailing comma.
+ AND
+ * All of the requirements listed in BaseStringSplitter's docstring.
+
+ Transformations:
+ The string mentioned in the 'Requirements' section is split into as
+ many substrings as necessary to adhere to the configured line length.
+
+ In the final set of substrings, no substring should be smaller than
+ MIN_SUBSTR_SIZE characters.
+
+ The string will ONLY be split on spaces (i.e. each new substring should
+ start with a space). Note that the string will NOT be split on a space
+ which is escaped with a backslash.
+
+ If the string is an f-string, it will NOT be split in the middle of an
+ f-expression (e.g. in f"FooBar: {foo() if x else bar()}", {foo() if x
+ else bar()} is an f-expression).
+
+ If the string that is being split has an associated set of custom split
+ records and those custom splits will NOT result in any line going over
+ the configured line length, those custom splits are used. Otherwise the
+ string is split as late as possible (from left-to-right) while still
+ adhering to the transformation rules listed above.
+
+ Collaborations:
+ StringSplitter relies on StringMerger to construct the appropriate
+ CustomSplit objects and add them to the custom split map.
+ """
+
+ MIN_SUBSTR_SIZE = 6
+ # Matches an "f-expression" (e.g. {var}) that might be found in an f-string.
+ RE_FEXPR = r"""
+ (?<!\{) (?:\{\{)* \{ (?!\{)
+ (?:
+ [^\{\}]
+ | \{\{
+ | \}\}
+ | (?R)
+ )+?
+ (?<!\}) \} (?:\}\})* (?!\})
+ """
+
+ def do_splitter_match(self, line: Line) -> TMatchResult:
+ LL = line.leaves
+
+ is_valid_index = is_valid_index_factory(LL)
+
+ idx = 0
+
+ # The first leaf MAY be a '+' symbol...
+ if is_valid_index(idx) and LL[idx].type == token.PLUS:
+ idx += 1
+
+ # The next/first leaf MAY be an empty LPAR...
+ if is_valid_index(idx) and is_empty_lpar(LL[idx]):
+ idx += 1
+
+ # The next/first leaf MUST be a string...
+ if not is_valid_index(idx) or LL[idx].type != token.STRING:
+ return TErr("Line does not start with a string.")
+
+ string_idx = idx
+
+ # Skip the string trailer, if one exists.
+ string_parser = StringParser()
+ idx = string_parser.parse(LL, string_idx)
+
+ # That string MAY be followed by an empty RPAR...
+ if is_valid_index(idx) and is_empty_rpar(LL[idx]):
+ idx += 1
+
+ # That string / empty RPAR leaf MAY be followed by a comma...
+ if is_valid_index(idx) and LL[idx].type == token.COMMA:
+ idx += 1
+
+ # But no more leaves are allowed...
+ if is_valid_index(idx):
+ return TErr("This line does not end with a string.")
+
+ return Ok(string_idx)
+
+ def do_transform(self, line: Line, string_idx: int) -> Iterator[TResult[Line]]:
+ LL = line.leaves
+
+ QUOTE = LL[string_idx].value[-1]
+
+ is_valid_index = is_valid_index_factory(LL)
+ insert_str_child = insert_str_child_factory(LL[string_idx])
+
+ prefix = get_string_prefix(LL[string_idx].value)
+
+ # We MAY choose to drop the 'f' prefix from substrings that don't
+ # contain any f-expressions, but ONLY if the original f-string
+ # contains at least one f-expression. Otherwise, we will alter the AST
+ # of the program.
+ drop_pointless_f_prefix = ("f" in prefix) and re.search(
+ self.RE_FEXPR, LL[string_idx].value, re.VERBOSE
+ )
+
+ first_string_line = True
+ starts_with_plus = LL[0].type == token.PLUS
+
+ def line_needs_plus() -> bool:
+ return first_string_line and starts_with_plus
+
+ def maybe_append_plus(new_line: Line) -> None:
+ """
+ Side Effects:
+ If @line starts with a plus and this is the first line we are
+ constructing, this function appends a PLUS leaf to @new_line
+ and replaces the old PLUS leaf in the node structure. Otherwise
+ this function does nothing.
+ """
+ if line_needs_plus():
+ plus_leaf = Leaf(token.PLUS, "+")
+ replace_child(LL[0], plus_leaf)
+ new_line.append(plus_leaf)
+
+ ends_with_comma = (
+ is_valid_index(string_idx + 1) and LL[string_idx + 1].type == token.COMMA
+ )
+
+ def max_last_string() -> int:
+ """
+ Returns:
+ The max allowed length of the string value used for the last
+ line we will construct.
+ """
+ result = self.line_length
+ result -= line.depth * 4
+ result -= 1 if ends_with_comma else 0
+ result -= 2 if line_needs_plus() else 0
+ return result
+
+ # --- Calculate Max Break Index (for string value)
+ # We start with the line length limit
+ max_break_idx = self.line_length
+ # The last index of a string of length N is N-1.
+ max_break_idx -= 1
+ # Leading whitespace is not present in the string value (e.g. Leaf.value).
+ max_break_idx -= line.depth * 4
+ if max_break_idx < 0:
+ yield TErr(
+ f"Unable to split {LL[string_idx].value} at such high of a line depth:"
+ f" {line.depth}"
+ )
+ return
+
+ # Check if StringMerger registered any custom splits.
+ custom_splits = self.pop_custom_splits(LL[string_idx].value)
+ # We use them ONLY if none of them would produce lines that exceed the
+ # line limit.
+ use_custom_breakpoints = bool(
+ custom_splits
+ and all(csplit.break_idx <= max_break_idx for csplit in custom_splits)
+ )
+
+ # Temporary storage for the remaining chunk of the string line that
+ # can't fit onto the line currently being constructed.
+ rest_value = LL[string_idx].value
+
+ def more_splits_should_be_made() -> bool:
+ """
+ Returns:
+ True iff `rest_value` (the remaining string value from the last
+ split), should be split again.
+ """
+ if use_custom_breakpoints:
+ return len(custom_splits) > 1
+ else:
+ return len(rest_value) > max_last_string()
+
+ string_line_results: List[Ok[Line]] = []
+ while more_splits_should_be_made():
+ if use_custom_breakpoints:
+ # Custom User Split (manual)
+ csplit = custom_splits.pop(0)
+ break_idx = csplit.break_idx
+ else:
+ # Algorithmic Split (automatic)
+ max_bidx = max_break_idx - 2 if line_needs_plus() else max_break_idx
+ maybe_break_idx = self._get_break_idx(rest_value, max_bidx)
+ if maybe_break_idx is None:
+ # If we are unable to algorithmically determine a good split
+ # and this string has custom splits registered to it, we
+ # fall back to using them--which means we have to start
+ # over from the beginning.
+ if custom_splits:
+ rest_value = LL[string_idx].value
+ string_line_results = []
+ first_string_line = True
+ use_custom_breakpoints = True
+ continue
+
+ # Otherwise, we stop splitting here.
+ break
+
+ break_idx = maybe_break_idx
+
+ # --- Construct `next_value`
+ next_value = rest_value[:break_idx] + QUOTE
+ if (
+ # Are we allowed to try to drop a pointless 'f' prefix?
+ drop_pointless_f_prefix
+ # If we are, will we be successful?
+ and next_value != self._normalize_f_string(next_value, prefix)
+ ):
+ # If the current custom split did NOT originally use a prefix,
+ # then `csplit.break_idx` will be off by one after removing
+ # the 'f' prefix.
+ break_idx = (
+ break_idx + 1
+ if use_custom_breakpoints and not csplit.has_prefix
+ else break_idx
+ )
+ next_value = rest_value[:break_idx] + QUOTE
+ next_value = self._normalize_f_string(next_value, prefix)
+
+ # --- Construct `next_leaf`
+ next_leaf = Leaf(token.STRING, next_value)
+ insert_str_child(next_leaf)
+ self._maybe_normalize_string_quotes(next_leaf)
+
+ # --- Construct `next_line`
+ next_line = line.clone()
+ maybe_append_plus(next_line)
+ next_line.append(next_leaf)
+ string_line_results.append(Ok(next_line))
+
+ rest_value = prefix + QUOTE + rest_value[break_idx:]
+ first_string_line = False
+
+ yield from string_line_results
+
+ if drop_pointless_f_prefix:
+ rest_value = self._normalize_f_string(rest_value, prefix)
+
+ rest_leaf = Leaf(token.STRING, rest_value)
+ insert_str_child(rest_leaf)
+
+ # NOTE: I could not find a test case that verifies that the following
+ # line is actually necessary, but it seems to be. Otherwise we risk
+ # not normalizing the last substring, right?
+ self._maybe_normalize_string_quotes(rest_leaf)
+
+ last_line = line.clone()
+ maybe_append_plus(last_line)
+
+ # If there are any leaves to the right of the target string...
+ if is_valid_index(string_idx + 1):
+ # We use `temp_value` here to determine how long the last line
+ # would be if we were to append all the leaves to the right of the
+ # target string to the last string line.
+ temp_value = rest_value
+ for leaf in LL[string_idx + 1 :]:
+ temp_value += str(leaf)
+ if leaf.type == token.LPAR:
+ break
+
+ # Try to fit them all on the same line with the last substring...
+ if (
+ len(temp_value) <= max_last_string()
+ or LL[string_idx + 1].type == token.COMMA
+ ):
+ last_line.append(rest_leaf)
+ append_leaves(last_line, line, LL[string_idx + 1 :])
+ yield Ok(last_line)
+ # Otherwise, place the last substring on one line and everything
+ # else on a line below that...
+ else:
+ last_line.append(rest_leaf)
+ yield Ok(last_line)
+
+ non_string_line = line.clone()
+ append_leaves(non_string_line, line, LL[string_idx + 1 :])
+ yield Ok(non_string_line)
+ # Else the target string was the last leaf...
+ else:
+ last_line.append(rest_leaf)
+ last_line.comments = line.comments.copy()
+ yield Ok(last_line)
+
+ def _get_break_idx(self, string: str, max_break_idx: int) -> Optional[int]:
+ """
+ This method contains the algorithm that StringSplitter uses to
+ determine which character to split each string at.
+
+ Args:
+ @string: The substring that we are attempting to split.
+ @max_break_idx: The ideal break index. We will return this value if it
+ meets all the necessary conditions. In the likely event that it
+ doesn't we will try to find the closest index BELOW @max_break_idx
+ that does. If that fails, we will expand our search by also
+ considering all valid indices ABOVE @max_break_idx.
+
+ Pre-Conditions:
+ * assert_is_leaf_string(@string)
+ * 0 <= @max_break_idx < len(@string)
+
+ Returns:
+ break_idx, if an index is able to be found that meets all of the
+ conditions listed in the 'Transformations' section of this classes'
+ docstring.
+ OR
+ None, otherwise.
+ """
+ is_valid_index = is_valid_index_factory(string)
+
+ assert is_valid_index(max_break_idx)
+ assert_is_leaf_string(string)
+
+ _fexpr_slices: Optional[List[Tuple[Index, Index]]] = None
+
+ def fexpr_slices() -> Iterator[Tuple[Index, Index]]:
+ """
+ Yields:
+ All ranges of @string which, if @string were to be split there,
+ would result in the splitting of an f-expression (which is NOT
+ allowed).
+ """
+ nonlocal _fexpr_slices
+
+ if _fexpr_slices is None:
+ _fexpr_slices = []
+ for match in re.finditer(self.RE_FEXPR, string, re.VERBOSE):
+ _fexpr_slices.append(match.span())
+
+ yield from _fexpr_slices
+
+ is_fstring = "f" in get_string_prefix(string)
+
+ def breaks_fstring_expression(i: Index) -> bool:
+ """
+ Returns:
+ True iff returning @i would result in the splitting of an
+ f-expression (which is NOT allowed).
+ """
+ if not is_fstring:
+ return False
+
+ for (start, end) in fexpr_slices():
+ if start <= i < end:
+ return True
+
+ return False
+
+ def passes_all_checks(i: Index) -> bool:
+ """
+ Returns:
+ True iff ALL of the conditions listed in the 'Transformations'
+ section of this classes' docstring would be be met by returning @i.
+ """
+ is_space = string[i] == " "
+
+ is_not_escaped = True
+ j = i - 1
+ while is_valid_index(j) and string[j] == "\\":
+ is_not_escaped = not is_not_escaped
+ j -= 1
+
+ is_big_enough = (
+ len(string[i:]) >= self.MIN_SUBSTR_SIZE
+ and len(string[:i]) >= self.MIN_SUBSTR_SIZE
+ )
+ return (
+ is_space
+ and is_not_escaped
+ and is_big_enough
+ and not breaks_fstring_expression(i)
+ )
+
+ # First, we check all indices BELOW @max_break_idx.
+ break_idx = max_break_idx
+ while is_valid_index(break_idx - 1) and not passes_all_checks(break_idx):
+ break_idx -= 1
+
+ if not passes_all_checks(break_idx):
+ # If that fails, we check all indices ABOVE @max_break_idx.
+ #
+ # If we are able to find a valid index here, the next line is going
+ # to be longer than the specified line length, but it's probably
+ # better than doing nothing at all.
+ break_idx = max_break_idx + 1
+ while is_valid_index(break_idx + 1) and not passes_all_checks(break_idx):
+ break_idx += 1
+
+ if not is_valid_index(break_idx) or not passes_all_checks(break_idx):
+ return None
+
+ return break_idx
+
+ def _maybe_normalize_string_quotes(self, leaf: Leaf) -> None:
+ if self.normalize_strings:
+ leaf.value = normalize_string_quotes(leaf.value)
+
+ def _normalize_f_string(self, string: str, prefix: str) -> str:
+ """
+ Pre-Conditions:
+ * assert_is_leaf_string(@string)
+
+ Returns:
+ * If @string is an f-string that contains no f-expressions, we
+ return a string identical to @string except that the 'f' prefix
+ has been stripped and all double braces (i.e. '{{' or '}}') have
+ been normalized (i.e. turned into '{' or '}').
+ OR
+ * Otherwise, we return @string.
+ """
+ assert_is_leaf_string(string)
+
+ if "f" in prefix and not re.search(self.RE_FEXPR, string, re.VERBOSE):
+ new_prefix = prefix.replace("f", "")
+
+ temp = string[len(prefix) :]
+ temp = re.sub(r"\{\{", "{", temp)
+ temp = re.sub(r"\}\}", "}", temp)
+ new_string = temp
+
+ return f"{new_prefix}{new_string}"
+ else:
+ return string
+
+
+class StringParenWrapper(CustomSplitMapMixin, BaseStringSplitter):
+ """
+ StringTransformer that splits non-"atom" strings (i.e. strings that do not
+ exist on lines by themselves).
+
+ Requirements:
+ All of the requirements listed in BaseStringSplitter's docstring in
+ addition to the requirements listed below:
+
+ * The line is a return/yield statement, which returns/yields a string.
+ OR
+ * The line is part of a ternary expression (e.g. `x = y if cond else
+ z`) such that the line starts with `else <string>`, where <string> is
+ some string.
+ OR
+ * The line is an assert statement, which ends with a string.
+ OR
+ * The line is an assignment statement (e.g. `x = <string>` or `x +=
+ <string>`) such that the variable is being assigned the value of some
+ string.
+ OR
+ * The line is a dictionary key assignment where some valid key is being
+ assigned the value of some string.
+
+ Transformations:
+ The chosen string is wrapped in parentheses and then split at the LPAR.
+
+ We then have one line which ends with an LPAR and another line that
+ starts with the chosen string. The latter line is then split again at
+ the RPAR. This results in the RPAR (and possibly a trailing comma)
+ being placed on its own line.
+
+ NOTE: If any leaves exist to the right of the chosen string (except
+ for a trailing comma, which would be placed after the RPAR), those
+ leaves are placed inside the parentheses. In effect, the chosen
+ string is not necessarily being "wrapped" by parentheses. We can,
+ however, count on the LPAR being placed directly before the chosen
+ string.
+
+ In other words, StringParenWrapper creates "atom" strings. These
+ can then be split again by StringSplitter, if necessary.
+
+ Collaborations:
+ In the event that a string line split by StringParenWrapper is
+ changed such that it no longer needs to be given its own line,
+ StringParenWrapper relies on StringParenStripper to clean up the
+ parentheses it created.
+ """
+
+ def do_splitter_match(self, line: Line) -> TMatchResult:
+ LL = line.leaves
+
+ string_idx = (
+ self._return_match(LL)
+ or self._else_match(LL)
+ or self._assert_match(LL)
+ or self._assign_match(LL)
+ or self._dict_match(LL)
+ )
+
+ if string_idx is not None:
+ string_value = line.leaves[string_idx].value
+ # If the string has no spaces...
+ if " " not in string_value:
+ # And will still violate the line length limit when split...
+ max_string_length = self.line_length - ((line.depth + 1) * 4)
+ if len(string_value) > max_string_length:
+ # And has no associated custom splits...
+ if not self.has_custom_splits(string_value):
+ # Then we should NOT put this string on its own line.
+ return TErr(
+ "We do not wrap long strings in parentheses when the"
+ " resultant line would still be over the specified line"
+ " length and can't be split further by StringSplitter."
+ )
+ return Ok(string_idx)
+
+ return TErr("This line does not contain any non-atomic strings.")
+
+ @staticmethod
+ def _return_match(LL: List[Leaf]) -> Optional[int]:
+ """
+ Returns:
+ string_idx such that @LL[string_idx] is equal to our target (i.e.
+ matched) string, if this line matches the return/yield statement
+ requirements listed in the 'Requirements' section of this classes'
+ docstring.
+ OR
+ None, otherwise.
+ """
+ # If this line is apart of a return/yield statement and the first leaf
+ # contains either the "return" or "yield" keywords...
+ if parent_type(LL[0]) in [syms.return_stmt, syms.yield_expr] and LL[
+ 0
+ ].value in ["return", "yield"]:
+ is_valid_index = is_valid_index_factory(LL)
+
+ idx = 2 if is_valid_index(1) and is_empty_par(LL[1]) else 1
+ # The next visible leaf MUST contain a string...
+ if is_valid_index(idx) and LL[idx].type == token.STRING:
+ return idx
+
+ return None
+
+ @staticmethod
+ def _else_match(LL: List[Leaf]) -> Optional[int]:
+ """
+ Returns:
+ string_idx such that @LL[string_idx] is equal to our target (i.e.
+ matched) string, if this line matches the ternary expression
+ requirements listed in the 'Requirements' section of this classes'
+ docstring.
+ OR
+ None, otherwise.
+ """
+ # If this line is apart of a ternary expression and the first leaf
+ # contains the "else" keyword...
+ if (
+ parent_type(LL[0]) == syms.test
+ and LL[0].type == token.NAME
+ and LL[0].value == "else"
+ ):
+ is_valid_index = is_valid_index_factory(LL)
+
+ idx = 2 if is_valid_index(1) and is_empty_par(LL[1]) else 1
+ # The next visible leaf MUST contain a string...
+ if is_valid_index(idx) and LL[idx].type == token.STRING:
+ return idx
+
+ return None
+
+ @staticmethod
+ def _assert_match(LL: List[Leaf]) -> Optional[int]:
+ """
+ Returns:
+ string_idx such that @LL[string_idx] is equal to our target (i.e.
+ matched) string, if this line matches the assert statement
+ requirements listed in the 'Requirements' section of this classes'
+ docstring.
+ OR
+ None, otherwise.
+ """
+ # If this line is apart of an assert statement and the first leaf
+ # contains the "assert" keyword...
+ if parent_type(LL[0]) == syms.assert_stmt and LL[0].value == "assert":
+ is_valid_index = is_valid_index_factory(LL)
+
+ for (i, leaf) in enumerate(LL):
+ # We MUST find a comma...
+ if leaf.type == token.COMMA:
+ idx = i + 2 if is_empty_par(LL[i + 1]) else i + 1
+
+ # That comma MUST be followed by a string...
+ if is_valid_index(idx) and LL[idx].type == token.STRING:
+ string_idx = idx
+
+ # Skip the string trailer, if one exists.
+ string_parser = StringParser()
+ idx = string_parser.parse(LL, string_idx)
+
+ # But no more leaves are allowed...
+ if not is_valid_index(idx):
+ return string_idx
+
+ return None
+
+ @staticmethod
+ def _assign_match(LL: List[Leaf]) -> Optional[int]:
+ """
+ Returns:
+ string_idx such that @LL[string_idx] is equal to our target (i.e.
+ matched) string, if this line matches the assignment statement
+ requirements listed in the 'Requirements' section of this classes'
+ docstring.
+ OR
+ None, otherwise.
+ """
+ # If this line is apart of an expression statement or is a function
+ # argument AND the first leaf contains a variable name...
+ if (
+ parent_type(LL[0]) in [syms.expr_stmt, syms.argument, syms.power]
+ and LL[0].type == token.NAME
+ ):
+ is_valid_index = is_valid_index_factory(LL)
+
+ for (i, leaf) in enumerate(LL):
+ # We MUST find either an '=' or '+=' symbol...
+ if leaf.type in [token.EQUAL, token.PLUSEQUAL]:
+ idx = i + 2 if is_empty_par(LL[i + 1]) else i + 1
+
+ # That symbol MUST be followed by a string...
+ if is_valid_index(idx) and LL[idx].type == token.STRING:
+ string_idx = idx
+
+ # Skip the string trailer, if one exists.
+ string_parser = StringParser()
+ idx = string_parser.parse(LL, string_idx)
+
+ # The next leaf MAY be a comma iff this line is apart
+ # of a function argument...
+ if (
+ parent_type(LL[0]) == syms.argument
+ and is_valid_index(idx)
+ and LL[idx].type == token.COMMA
+ ):
+ idx += 1
+
+ # But no more leaves are allowed...
+ if not is_valid_index(idx):
+ return string_idx
+
+ return None
+
+ @staticmethod
+ def _dict_match(LL: List[Leaf]) -> Optional[int]:
+ """
+ Returns:
+ string_idx such that @LL[string_idx] is equal to our target (i.e.
+ matched) string, if this line matches the dictionary key assignment
+ statement requirements listed in the 'Requirements' section of this
+ classes' docstring.
+ OR
+ None, otherwise.
+ """
+ # If this line is apart of a dictionary key assignment...
+ if syms.dictsetmaker in [parent_type(LL[0]), parent_type(LL[0].parent)]:
+ is_valid_index = is_valid_index_factory(LL)
+
+ for (i, leaf) in enumerate(LL):
+ # We MUST find a colon...
+ if leaf.type == token.COLON:
+ idx = i + 2 if is_empty_par(LL[i + 1]) else i + 1
+
+ # That colon MUST be followed by a string...
+ if is_valid_index(idx) and LL[idx].type == token.STRING:
+ string_idx = idx
+
+ # Skip the string trailer, if one exists.
+ string_parser = StringParser()
+ idx = string_parser.parse(LL, string_idx)
+
+ # That string MAY be followed by a comma...
+ if is_valid_index(idx) and LL[idx].type == token.COMMA:
+ idx += 1
+
+ # But no more leaves are allowed...
+ if not is_valid_index(idx):
+ return string_idx
+
+ return None
+
+ def do_transform(self, line: Line, string_idx: int) -> Iterator[TResult[Line]]:
+ LL = line.leaves
+
+ is_valid_index = is_valid_index_factory(LL)
+ insert_str_child = insert_str_child_factory(LL[string_idx])
+
+ comma_idx = -1
+ ends_with_comma = False
+ if LL[comma_idx].type == token.COMMA:
+ ends_with_comma = True
+
+ leaves_to_steal_comments_from = [LL[string_idx]]
+ if ends_with_comma:
+ leaves_to_steal_comments_from.append(LL[comma_idx])
+
+ # --- First Line
+ first_line = line.clone()
+ left_leaves = LL[:string_idx]
+
+ # We have to remember to account for (possibly invisible) LPAR and RPAR
+ # leaves that already wrapped the target string. If these leaves do
+ # exist, we will replace them with our own LPAR and RPAR leaves.
+ old_parens_exist = False
+ if left_leaves and left_leaves[-1].type == token.LPAR:
+ old_parens_exist = True
+ leaves_to_steal_comments_from.append(left_leaves[-1])
+ left_leaves.pop()
+
+ append_leaves(first_line, line, left_leaves)
+
+ lpar_leaf = Leaf(token.LPAR, "(")
+ if old_parens_exist:
+ replace_child(LL[string_idx - 1], lpar_leaf)
+ else:
+ insert_str_child(lpar_leaf)
+ first_line.append(lpar_leaf)
+
+ # We throw inline comments that were originally to the right of the
+ # target string to the top line. They will now be shown to the right of
+ # the LPAR.
+ for leaf in leaves_to_steal_comments_from:
+ for comment_leaf in line.comments_after(leaf):
+ first_line.append(comment_leaf, preformatted=True)
+
+ yield Ok(first_line)
+
+ # --- Middle (String) Line
+ # We only need to yield one (possibly too long) string line, since the
+ # `StringSplitter` will break it down further if necessary.
+ string_value = LL[string_idx].value
+ string_line = Line(
+ mode=line.mode,
+ depth=line.depth + 1,
+ inside_brackets=True,
+ should_split_rhs=line.should_split_rhs,
+ magic_trailing_comma=line.magic_trailing_comma,
+ )
+ string_leaf = Leaf(token.STRING, string_value)
+ insert_str_child(string_leaf)
+ string_line.append(string_leaf)
+
+ old_rpar_leaf = None
+ if is_valid_index(string_idx + 1):
+ right_leaves = LL[string_idx + 1 :]
+ if ends_with_comma:
+ right_leaves.pop()
+
+ if old_parens_exist:
+ assert (
+ right_leaves and right_leaves[-1].type == token.RPAR
+ ), "Apparently, old parentheses do NOT exist?!"
+ old_rpar_leaf = right_leaves.pop()
+
+ append_leaves(string_line, line, right_leaves)
+
+ yield Ok(string_line)
+
+ # --- Last Line
+ last_line = line.clone()
+ last_line.bracket_tracker = first_line.bracket_tracker
+
+ new_rpar_leaf = Leaf(token.RPAR, ")")
+ if old_rpar_leaf is not None:
+ replace_child(old_rpar_leaf, new_rpar_leaf)
+ else:
+ insert_str_child(new_rpar_leaf)
+ last_line.append(new_rpar_leaf)
+
+ # If the target string ended with a comma, we place this comma to the
+ # right of the RPAR on the last line.
+ if ends_with_comma:
+ comma_leaf = Leaf(token.COMMA, ",")
+ replace_child(LL[comma_idx], comma_leaf)
+ last_line.append(comma_leaf)
+
+ yield Ok(last_line)
+
+
+class StringParser:
+ """
+ A state machine that aids in parsing a string's "trailer", which can be
+ either non-existent, an old-style formatting sequence (e.g. `% varX` or `%
+ (varX, varY)`), or a method-call / attribute access (e.g. `.format(varX,
+ varY)`).
+
+ NOTE: A new StringParser object MUST be instantiated for each string
+ trailer we need to parse.
+
+ Examples:
+ We shall assume that `line` equals the `Line` object that corresponds
+ to the following line of python code:
+ ```
+ x = "Some {}.".format("String") + some_other_string
+ ```
+
+ Furthermore, we will assume that `string_idx` is some index such that:
+ ```
+ assert line.leaves[string_idx].value == "Some {}."
+ ```
+
+ The following code snippet then holds:
+ ```
+ string_parser = StringParser()
+ idx = string_parser.parse(line.leaves, string_idx)
+ assert line.leaves[idx].type == token.PLUS
+ ```
+ """
+
+ DEFAULT_TOKEN = -1
+
+ # String Parser States
+ START = 1
+ DOT = 2
+ NAME = 3
+ PERCENT = 4
+ SINGLE_FMT_ARG = 5
+ LPAR = 6
+ RPAR = 7
+ DONE = 8
+
+ # Lookup Table for Next State
+ _goto: Dict[Tuple[ParserState, NodeType], ParserState] = {
+ # A string trailer may start with '.' OR '%'.
+ (START, token.DOT): DOT,
+ (START, token.PERCENT): PERCENT,
+ (START, DEFAULT_TOKEN): DONE,
+ # A '.' MUST be followed by an attribute or method name.
+ (DOT, token.NAME): NAME,
+ # A method name MUST be followed by an '(', whereas an attribute name
+ # is the last symbol in the string trailer.
+ (NAME, token.LPAR): LPAR,
+ (NAME, DEFAULT_TOKEN): DONE,
+ # A '%' symbol can be followed by an '(' or a single argument (e.g. a
+ # string or variable name).
+ (PERCENT, token.LPAR): LPAR,
+ (PERCENT, DEFAULT_TOKEN): SINGLE_FMT_ARG,
+ # If a '%' symbol is followed by a single argument, that argument is
+ # the last leaf in the string trailer.
+ (SINGLE_FMT_ARG, DEFAULT_TOKEN): DONE,
+ # If present, a ')' symbol is the last symbol in a string trailer.
+ # (NOTE: LPARS and nested RPARS are not included in this lookup table,
+ # since they are treated as a special case by the parsing logic in this
+ # classes' implementation.)
+ (RPAR, DEFAULT_TOKEN): DONE,
+ }
+
+ def __init__(self) -> None:
+ self._state = self.START
+ self._unmatched_lpars = 0
+
+ def parse(self, leaves: List[Leaf], string_idx: int) -> int:
+ """
+ Pre-conditions:
+ * @leaves[@string_idx].type == token.STRING
+
+ Returns:
+ The index directly after the last leaf which is apart of the string
+ trailer, if a "trailer" exists.
+ OR
+ @string_idx + 1, if no string "trailer" exists.
+ """
+ assert leaves[string_idx].type == token.STRING
+
+ idx = string_idx + 1
+ while idx < len(leaves) and self._next_state(leaves[idx]):
+ idx += 1
+ return idx
+
+ def _next_state(self, leaf: Leaf) -> bool:
+ """
+ Pre-conditions:
+ * On the first call to this function, @leaf MUST be the leaf that
+ was directly after the string leaf in question (e.g. if our target
+ string is `line.leaves[i]` then the first call to this method must
+ be `line.leaves[i + 1]`).
+ * On the next call to this function, the leaf parameter passed in
+ MUST be the leaf directly following @leaf.
+
+ Returns:
+ True iff @leaf is apart of the string's trailer.
+ """
+ # We ignore empty LPAR or RPAR leaves.
+ if is_empty_par(leaf):
+ return True
+
+ next_token = leaf.type
+ if next_token == token.LPAR:
+ self._unmatched_lpars += 1
+
+ current_state = self._state
+
+ # The LPAR parser state is a special case. We will return True until we
+ # find the matching RPAR token.
+ if current_state == self.LPAR:
+ if next_token == token.RPAR:
+ self._unmatched_lpars -= 1
+ if self._unmatched_lpars == 0:
+ self._state = self.RPAR
+ # Otherwise, we use a lookup table to determine the next state.
+ else:
+ # If the lookup table matches the current state to the next
+ # token, we use the lookup table.
+ if (current_state, next_token) in self._goto:
+ self._state = self._goto[current_state, next_token]
+ else:
+ # Otherwise, we check if a the current state was assigned a
+ # default.
+ if (current_state, self.DEFAULT_TOKEN) in self._goto:
+ self._state = self._goto[current_state, self.DEFAULT_TOKEN]
+ # If no default has been assigned, then this parser has a logic
+ # error.
+ else:
+ raise RuntimeError(f"{self.__class__.__name__} LOGIC ERROR!")
+
+ if self._state == self.DONE:
+ return False
+
+ return True
+
+
+def insert_str_child_factory(string_leaf: Leaf) -> Callable[[LN], None]:
+ """
+ Factory for a convenience function that is used to orphan @string_leaf
+ and then insert multiple new leaves into the same part of the node
+ structure that @string_leaf had originally occupied.
+
+ Examples:
+ Let `string_leaf = Leaf(token.STRING, '"foo"')` and `N =
+ string_leaf.parent`. Assume the node `N` has the following
+ original structure:
+
+ Node(
+ expr_stmt, [
+ Leaf(NAME, 'x'),
+ Leaf(EQUAL, '='),
+ Leaf(STRING, '"foo"'),
+ ]
+ )
+
+ We then run the code snippet shown below.
+ ```
+ insert_str_child = insert_str_child_factory(string_leaf)
+
+ lpar = Leaf(token.LPAR, '(')
+ insert_str_child(lpar)
+
+ bar = Leaf(token.STRING, '"bar"')
+ insert_str_child(bar)
+
+ rpar = Leaf(token.RPAR, ')')
+ insert_str_child(rpar)
+ ```
+
+ After which point, it follows that `string_leaf.parent is None` and
+ the node `N` now has the following structure:
+
+ Node(
+ expr_stmt, [
+ Leaf(NAME, 'x'),
+ Leaf(EQUAL, '='),
+ Leaf(LPAR, '('),
+ Leaf(STRING, '"bar"'),
+ Leaf(RPAR, ')'),
+ ]
+ )
+ """
+ string_parent = string_leaf.parent
+ string_child_idx = string_leaf.remove()
+
+ def insert_str_child(child: LN) -> None:
+ nonlocal string_child_idx
+
+ assert string_parent is not None
+ assert string_child_idx is not None
+
+ string_parent.insert_child(string_child_idx, child)
+ string_child_idx += 1
+
+ return insert_str_child
+
+
+def is_valid_index_factory(seq: Sequence[Any]) -> Callable[[int], bool]:
+ """
+ Examples:
+ ```
+ my_list = [1, 2, 3]
+
+ is_valid_index = is_valid_index_factory(my_list)
+
+ assert is_valid_index(0)
+ assert is_valid_index(2)
+
+ assert not is_valid_index(3)
+ assert not is_valid_index(-1)
+ ```
+ """
+
+ def is_valid_index(idx: int) -> bool:
+ """
+ Returns:
+ True iff @idx is positive AND seq[@idx] does NOT raise an
+ IndexError.
+ """
+ return 0 <= idx < len(seq)
+
+ return is_valid_index
diff --git a/tests/test_black.py b/tests/test_black.py
index b8e526a..29a0731 100644
--- a/tests/test_black.py
+++ b/tests/test_black.py
@@ -34,6 +34,10 @@ from click.testing import CliRunner
import black
from black import Feature, TargetVersion
+from black.cache import get_cache_file
+from black.debug import DebugVisitor
+from black.report import Report
+import black.files
from pathspec import PathSpec
@@ -69,7 +73,7 @@ def cache_dir(exists: bool = True) -> Iterator[Path]:
cache_dir = Path(workspace)
if not exists:
cache_dir = cache_dir / "new"
- with patch("black.CACHE_DIR", cache_dir):
+ with patch("black.cache.CACHE_DIR", cache_dir):
yield cache_dir
@@ -582,7 +586,7 @@ class BlackTestCase(BlackBaseTestCase):
self.assertFormatEqual(contents_spc, fs(contents_tab))
def test_report_verbose(self) -> None:
- report = black.Report(verbose=True)
+ report = Report(verbose=True)
out_lines = []
err_lines = []
@@ -592,7 +596,7 @@ class BlackTestCase(BlackBaseTestCase):
def err(msg: str, **kwargs: Any) -> None:
err_lines.append(msg)
- with patch("black.out", out), patch("black.err", err):
+ with patch("black.output._out", out), patch("black.output._err", err):
report.done(Path("f1"), black.Changed.NO)
self.assertEqual(len(out_lines), 1)
self.assertEqual(len(err_lines), 0)
@@ -684,7 +688,7 @@ class BlackTestCase(BlackBaseTestCase):
)
def test_report_quiet(self) -> None:
- report = black.Report(quiet=True)
+ report = Report(quiet=True)
out_lines = []
err_lines = []
@@ -694,7 +698,7 @@ class BlackTestCase(BlackBaseTestCase):
def err(msg: str, **kwargs: Any) -> None:
err_lines.append(msg)
- with patch("black.out", out), patch("black.err", err):
+ with patch("black.output._out", out), patch("black.output._err", err):
report.done(Path("f1"), black.Changed.NO)
self.assertEqual(len(out_lines), 0)
self.assertEqual(len(err_lines), 0)
@@ -788,7 +792,7 @@ class BlackTestCase(BlackBaseTestCase):
def err(msg: str, **kwargs: Any) -> None:
err_lines.append(msg)
- with patch("black.out", out), patch("black.err", err):
+ with patch("black.output._out", out), patch("black.output._err", err):
report.done(Path("f1"), black.Changed.NO)
self.assertEqual(len(out_lines), 0)
self.assertEqual(len(err_lines), 0)
@@ -1005,8 +1009,8 @@ class BlackTestCase(BlackBaseTestCase):
def err(msg: str, **kwargs: Any) -> None:
err_lines.append(msg)
- with patch("black.out", out), patch("black.err", err):
- black.DebugVisitor.show(source)
+ with patch("black.debug.out", out):
+ DebugVisitor.show(source)
actual = "\n".join(out_lines) + "\n"
log_name = ""
if expected != actual:
@@ -1054,7 +1058,7 @@ class BlackTestCase(BlackBaseTestCase):
def err(msg: str, **kwargs: Any) -> None:
err_lines.append(msg)
- with patch("black.out", out), patch("black.err", err):
+ with patch("black.output._out", out), patch("black.output._err", err):
with self.assertRaises(AssertionError):
self.assertFormatEqual("j = [1, 2, 3]", "j = [1, 2, 3,]")
@@ -1066,7 +1070,7 @@ class BlackTestCase(BlackBaseTestCase):
def test_cache_broken_file(self) -> None:
mode = DEFAULT_MODE
with cache_dir() as workspace:
- cache_file = black.get_cache_file(mode)
+ cache_file = get_cache_file(mode)
with cache_file.open("w") as fobj:
fobj.write("this is not a pickle")
self.assertEqual(black.read_cache(mode), {})
@@ -1120,7 +1124,7 @@ class BlackTestCase(BlackBaseTestCase):
"black.write_cache"
) as write_cache:
self.invokeBlack([str(src), "--diff"])
- cache_file = black.get_cache_file(mode)
+ cache_file = get_cache_file(mode)
self.assertFalse(cache_file.exists())
write_cache.assert_not_called()
read_cache.assert_not_called()
@@ -1135,7 +1139,7 @@ class BlackTestCase(BlackBaseTestCase):
"black.write_cache"
) as write_cache:
self.invokeBlack([str(src), "--diff", "--color"])
- cache_file = black.get_cache_file(mode)
+ cache_file = get_cache_file(mode)
self.assertFalse(cache_file.exists())
write_cache.assert_not_called()
read_cache.assert_not_called()
@@ -1173,7 +1177,7 @@ class BlackTestCase(BlackBaseTestCase):
black.main, ["-"], input=BytesIO(b"print('hello')")
)
self.assertEqual(result.exit_code, 0)
- cache_file = black.get_cache_file(mode)
+ cache_file = get_cache_file(mode)
self.assertFalse(cache_file.exists())
def test_read_cache_no_cachefile(self) -> None:
@@ -1960,7 +1964,10 @@ class BlackTestCase(BlackBaseTestCase):
self.assertEqual(black.find_project_root((src_dir,)), src_dir.resolve())
self.assertEqual(black.find_project_root((src_python,)), src_dir.resolve())
- @patch("black.find_user_pyproject_toml", black.find_user_pyproject_toml.__wrapped__)
+ @patch(
+ "black.files.find_user_pyproject_toml",
+ black.files.find_user_pyproject_toml.__wrapped__,
+ )
def test_find_user_pyproject_toml_linux(self) -> None:
if system() == "Windows":
return
@@ -1970,7 +1977,7 @@ class BlackTestCase(BlackBaseTestCase):
tmp_user_config = Path(workspace) / "black"
with patch.dict("os.environ", {"XDG_CONFIG_HOME": workspace}):
self.assertEqual(
- black.find_user_pyproject_toml(), tmp_user_config.resolve()
+ black.files.find_user_pyproject_toml(), tmp_user_config.resolve()
)
# Test fallback for XDG_CONFIG_HOME
@@ -1978,7 +1985,7 @@ class BlackTestCase(BlackBaseTestCase):
os.environ.pop("XDG_CONFIG_HOME", None)
fallback_user_config = Path("~/.config").expanduser() / "black"
self.assertEqual(
- black.find_user_pyproject_toml(), fallback_user_config.resolve()
+ black.files.find_user_pyproject_toml(), fallback_user_config.resolve()
)
def test_find_user_pyproject_toml_windows(self) -> None:
@@ -1986,7 +1993,9 @@ class BlackTestCase(BlackBaseTestCase):
return
user_config_path = Path.home() / ".black"
- self.assertEqual(black.find_user_pyproject_toml(), user_config_path.resolve())
+ self.assertEqual(
+ black.files.find_user_pyproject_toml(), user_config_path.resolve()
+ )
def test_bpo_33660_workaround(self) -> None:
if system() == "Windows":
diff --git a/tests/test_format.py b/tests/test_format.py
index 78f2b55..e59d521 100644
--- a/tests/test_format.py
+++ b/tests/test_format.py
@@ -71,10 +71,27 @@ EXPERIMENTAL_STRING_PROCESSING_CASES = [
SOURCES = [
- "tests/test_black.py",
- "tests/test_format.py",
- "tests/test_blackd.py",
"src/black/__init__.py",
+ "src/black/__main__.py",
+ "src/black/brackets.py",
+ "src/black/cache.py",
+ "src/black/comments.py",
+ "src/black/concurrency.py",
+ "src/black/const.py",
+ "src/black/debug.py",
+ "src/black/files.py",
+ "src/black/linegen.py",
+ "src/black/lines.py",
+ "src/black/mode.py",
+ "src/black/nodes.py",
+ "src/black/numerics.py",
+ "src/black/output.py",
+ "src/black/parsing.py",
+ "src/black/report.py",
+ "src/black/rusty.py",
+ "src/black/strings.py",
+ "src/black/trans.py",
+ "src/blackd/__init__.py",
"src/blib2to3/pygram.py",
"src/blib2to3/pytree.py",
"src/blib2to3/pgen2/conv.py",
@@ -86,6 +103,13 @@ SOURCES = [
"src/blib2to3/pgen2/tokenize.py",
"src/blib2to3/pgen2/token.py",
"setup.py",
+ "tests/test_black.py",
+ "tests/test_blackd.py",
+ "tests/test_format.py",
+ "tests/test_primer.py",
+ "tests/optional.py",
+ "tests/util.py",
+ "tests/conftest.py",
]
diff --git a/tests/util.py b/tests/util.py
index 3670952..1e86a3f 100644
--- a/tests/util.py
+++ b/tests/util.py
@@ -2,9 +2,12 @@ import os
import unittest
from pathlib import Path
from typing import List, Tuple, Any
-import black
from functools import partial
+import black
+from black.output import out, err
+from black.debug import DebugVisitor
+
THIS_DIR = Path(__file__).parent
PROJECT_ROOT = THIS_DIR.parent
EMPTY_LINE = "# EMPTY LINE WITH WHITESPACE" + " (this comment will be removed)"
@@ -26,21 +29,21 @@ class BlackBaseTestCase(unittest.TestCase):
def assertFormatEqual(self, expected: str, actual: str) -> None:
if actual != expected and not os.environ.get("SKIP_AST_PRINT"):
- bdv: black.DebugVisitor[Any]
- black.out("Expected tree:", fg="green")
+ bdv: DebugVisitor[Any]
+ out("Expected tree:", fg="green")
try:
exp_node = black.lib2to3_parse(expected)
- bdv = black.DebugVisitor()
+ bdv = DebugVisitor()
list(bdv.visit(exp_node))
except Exception as ve:
- black.err(str(ve))
- black.out("Actual tree:", fg="red")
+ err(str(ve))
+ out("Actual tree:", fg="red")
try:
exp_node = black.lib2to3_parse(actual)
- bdv = black.DebugVisitor()
+ bdv = DebugVisitor()
list(bdv.visit(exp_node))
except Exception as ve:
- black.err(str(ve))
+ err(str(ve))
self.assertMultiLineEqual(expected, actual)
--
2.39.5