-#!/usr/bin/env python3
+import ast
import asyncio
-from asyncio.base_events import BaseEventLoop
-from concurrent.futures import Executor, ProcessPoolExecutor
-from functools import partial
-import keyword
+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 (
- Dict, Generic, Iterable, Iterator, List, Optional, Set, Tuple, TypeVar, Union
+ Any,
+ Callable,
+ Collection,
+ Dict,
+ Generator,
+ Generic,
+ Iterable,
+ Iterator,
+ List,
+ Optional,
+ Pattern,
+ Sequence,
+ Set,
+ Tuple,
+ Type,
+ TypeVar,
+ Union,
+ cast,
+ TYPE_CHECKING,
)
+from typing_extensions import Final
+from mypy_extensions import mypyc_attr
-from attr import attrib, dataclass, Factory
+from appdirs import user_cache_dir
+from dataclasses import dataclass, field, replace
import click
+import toml
+from typed_ast import ast3, ast27
+from pathspec import PathSpec
# 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
-__version__ = "18.3a1"
+from _black_version import version as __version__
+
+if TYPE_CHECKING:
+ import colorama # noqa: F401
+
DEFAULT_LINE_LENGTH = 88
+DEFAULT_EXCLUDES = r"/(\.eggs|\.git|\.hg|\.mypy_cache|\.nox|\.tox|\.venv|\.svn|_build|buck-out|build|dist)/" # noqa: B950
+DEFAULT_INCLUDES = r"\.pyi?$"
+CACHE_DIR = Path(user_cache_dir("black", version=__version__))
+
+STRING_PREFIX_CHARS: Final = "furbFURB" # All possible string prefix characters.
+
+
# types
-syms = pygram.python_symbols
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[Path, CacheInfo]
out = partial(click.secho, bold=True, err=True)
-err = partial(click.secho, fg='red', err=True)
+err = partial(click.secho, fg="red", err=True)
+
+pygram.initialize(CACHE_DIR)
+syms = pygram.python_symbols
class NothingChanged(UserWarning):
- """Raised by `format_file` when the reformatted code is the same as source."""
+ """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."""
+
+
+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
+ DIFF = 2
+ CHECK = 3
+ COLOR_DIFF = 4
+
+ @classmethod
+ def from_configuration(
+ cls, *, check: bool, diff: bool, color: bool = False
+ ) -> "WriteBack":
+ if check and not diff:
+ return cls.CHECK
+
+ if diff and color:
+ return cls.COLOR_DIFF
+
+ 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
+
+ def is_python2(self) -> bool:
+ return self is TargetVersion.PY27
+
+
+PY36_VERSIONS = {TargetVersion.PY36, TargetVersion.PY37, TargetVersion.PY38}
+
+
+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
+
+
+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,
+ },
+}
+
+
+@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
+
+ 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)),
+ ]
+ 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)
-class CannotSplit(Exception):
- """A readable split that fits the allotted line length is impossible.
+def find_pyproject_toml(path_search_start: 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"
+ return str(path_pyproject_toml) if path_pyproject_toml.is_file() else None
- Raised by `left_hand_split()` and `right_hand_split()`.
+
+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]:
+ """Inject Black configuration from "pyproject.toml" into defaults in `ctx`.
+
+ Returns the path to a successfully found and read configuration file, None
+ otherwise.
+ """
+ if not value:
+ value = find_pyproject_toml(ctx.params.get("src", ()))
+ if value is None:
+ return None
+
+ try:
+ config = parse_pyproject_toml(value)
+ except (toml.TomlDecodeError, OSError) as e:
+ raise click.FileError(
+ filename=value, hint=f"Error reading configuration file: {e}"
+ )
+
+ if not config:
+ return None
+
+ target_version = config.get("target_version")
+ if target_version is not None and not isinstance(target_version, list):
+ raise click.BadOptionUsage(
+ "target-version", f"Config key target-version must be a list"
+ )
+
+ default_map: Dict[str, Any] = {}
+ if ctx.default_map:
+ default_map.update(ctx.default_map)
+ default_map.update(config)
+
+ ctx.default_map = default_map
+ return value
+
+
+def target_version_option_callback(
+ c: click.Context, p: Union[click.Option, click.Parameter], v: Tuple[str, ...]
+) -> List[TargetVersion]:
+ """Compute the target versions from a --target-version flag.
+
+ This is its own function because mypy couldn't infer the type correctly
+ when it was a lambda, causing mypyc trouble.
"""
+ return [TargetVersion[val.upper()] for val in v]
-@click.command()
+@click.command(context_settings=dict(help_option_names=["-h", "--help"]))
+@click.option("-c", "--code", type=str, help="Format the code passed in as a string.")
@click.option(
- '-l',
- '--line-length',
+ "-l",
+ "--line-length",
type=int,
default=DEFAULT_LINE_LENGTH,
- help='How many character per line to allow.',
+ help="How many characters per line to allow.",
+ show_default=True,
+)
+@click.option(
+ "-t",
+ "--target-version",
+ type=click.Choice([v.name.lower() for v in TargetVersion]),
+ callback=target_version_option_callback,
+ multiple=True,
+ help=(
+ "Python versions that should be supported by Black's output. [default: per-file"
+ " auto-detection]"
+ ),
+)
+@click.option(
+ "--py36",
+ is_flag=True,
+ help=(
+ "Allow using Python 3.6-only syntax on all input files. This will put trailing"
+ " commas in function signatures and calls also after *args and **kwargs."
+ " Deprecated; use --target-version instead. [default: per-file auto-detection]"
+ ),
+)
+@click.option(
+ "--pyi",
+ is_flag=True,
+ help=(
+ "Format all input files like typing stubs regardless of file extension (useful"
+ " when piping source on standard input)."
+ ),
+)
+@click.option(
+ "-S",
+ "--skip-string-normalization",
+ is_flag=True,
+ help="Don't normalize string quotes or prefixes.",
+)
+@click.option(
+ "--check",
+ is_flag=True,
+ help=(
+ "Don't write the files back, just return the status. Return code 0 means"
+ " nothing would change. Return code 1 means some files would be reformatted."
+ " Return code 123 means there was an internal error."
+ ),
+)
+@click.option(
+ "--diff",
+ is_flag=True,
+ help="Don't write the files back, just output a diff for each file on stdout.",
+)
+@click.option(
+ "--color/--no-color",
+ is_flag=True,
+ help="Show colored diff. Only applies when `--diff` is given.",
+)
+@click.option(
+ "--fast/--safe",
+ is_flag=True,
+ help="If --fast given, skip temporary sanity checks. [default: --safe]",
+)
+@click.option(
+ "--include",
+ type=str,
+ default=DEFAULT_INCLUDES,
+ help=(
+ "A regular expression that matches files and directories that should be"
+ " included on recursive searches. An empty value means all files are included"
+ " regardless of the name. Use forward slashes for directories on all platforms"
+ " (Windows, too). Exclusions are calculated first, inclusions later."
+ ),
+ show_default=True,
+)
+@click.option(
+ "--exclude",
+ type=str,
+ default=DEFAULT_EXCLUDES,
+ help=(
+ "A regular expression that matches files and directories that should be"
+ " excluded on recursive searches. An empty value means no paths are excluded."
+ " Use forward slashes for directories on all platforms (Windows, too). "
+ " Exclusions are calculated first, inclusions later."
+ ),
show_default=True,
)
@click.option(
- '--check',
+ "-q",
+ "--quiet",
is_flag=True,
help=(
- "Don't write back the files, just return the status. Return code 0 "
- "means nothing changed. Return code 1 means some files were "
- "reformatted. Return code 123 means there was an internal error."
+ "Don't emit non-error messages to stderr. Errors are still emitted; silence"
+ " those with 2>/dev/null."
),
)
@click.option(
- '--fast/--safe',
+ "-v",
+ "--verbose",
is_flag=True,
- help='If --fast given, skip temporary sanity checks. [default: --safe]',
+ help=(
+ "Also emit messages to stderr about files that were not changed or were ignored"
+ " due to --exclude=."
+ ),
)
@click.version_option(version=__version__)
@click.argument(
- 'src',
+ "src",
nargs=-1,
- type=click.Path(exists=True, file_okay=True, dir_okay=True, readable=True),
+ type=click.Path(
+ exists=True, file_okay=True, dir_okay=True, readable=True, allow_dash=True
+ ),
+ is_eager=True,
+)
+@click.option(
+ "--config",
+ type=click.Path(
+ exists=True,
+ file_okay=True,
+ dir_okay=False,
+ readable=True,
+ allow_dash=False,
+ path_type=str,
+ ),
+ is_eager=True,
+ callback=read_pyproject_toml,
+ help="Read configuration from PATH.",
)
@click.pass_context
def main(
- ctx: click.Context, line_length: int, check: bool, fast: bool, src: List[str]
+ ctx: click.Context,
+ code: Optional[str],
+ line_length: int,
+ target_version: List[TargetVersion],
+ check: bool,
+ diff: bool,
+ color: bool,
+ fast: bool,
+ pyi: bool,
+ py36: bool,
+ skip_string_normalization: bool,
+ quiet: bool,
+ verbose: bool,
+ include: str,
+ exclude: str,
+ src: Tuple[str, ...],
+ config: Optional[str],
) -> None:
"""The uncompromising code formatter."""
- sources: List[Path] = []
+ write_back = WriteBack.from_configuration(check=check, diff=diff, color=color)
+ if target_version:
+ if py36:
+ err("Cannot use both --target-version and --py36")
+ ctx.exit(2)
+ else:
+ versions = set(target_version)
+ elif py36:
+ err(
+ "--py36 is deprecated and will be removed in a future version. Use"
+ " --target-version py36 instead."
+ )
+ versions = PY36_VERSIONS
+ else:
+ # We'll autodetect later.
+ versions = set()
+ mode = Mode(
+ target_versions=versions,
+ line_length=line_length,
+ is_pyi=pyi,
+ string_normalization=not skip_string_normalization,
+ )
+ if config and verbose:
+ out(f"Using configuration from {config}.", bold=False, fg="blue")
+ if code is not None:
+ print(format_str(code, mode=mode))
+ ctx.exit(0)
+ try:
+ include_regex = re_compile_maybe_verbose(include)
+ except re.error:
+ err(f"Invalid regular expression for include given: {include!r}")
+ ctx.exit(2)
+ try:
+ exclude_regex = re_compile_maybe_verbose(exclude)
+ except re.error:
+ err(f"Invalid regular expression for exclude given: {exclude!r}")
+ ctx.exit(2)
+ report = Report(check=check, diff=diff, quiet=quiet, verbose=verbose)
+ root = find_project_root(src)
+ sources: Set[Path] = set()
+ path_empty(src, quiet, verbose, ctx)
for s in src:
p = Path(s)
if p.is_dir():
- sources.extend(gen_python_files_in_dir(p))
- elif p.is_file():
+ sources.update(
+ gen_python_files_in_dir(
+ p, root, include_regex, exclude_regex, report, get_gitignore(root)
+ )
+ )
+ elif p.is_file() or s == "-":
# if a file was explicitly given, we don't care about its extension
- sources.append(p)
+ sources.add(p)
else:
- err(f'invalid path: {s}')
+ err(f"invalid path: {s}")
if len(sources) == 0:
+ if verbose or not quiet:
+ out("No Python files are present to be formatted. Nothing to do 😴")
ctx.exit(0)
- elif len(sources) == 1:
- p = sources[0]
- report = Report()
- try:
- changed = format_file_in_place(
- p, line_length=line_length, fast=fast, write_back=not check
- )
- report.done(p, changed)
- except Exception as exc:
- report.failed(p, str(exc))
- ctx.exit(report.return_code)
+
+ if len(sources) == 1:
+ reformat_one(
+ src=sources.pop(),
+ fast=fast,
+ write_back=write_back,
+ mode=mode,
+ report=report,
+ )
else:
- loop = asyncio.get_event_loop()
- executor = ProcessPoolExecutor(max_workers=os.cpu_count())
- return_code = 1
- try:
- return_code = loop.run_until_complete(
- schedule_formatting(
- sources, line_length, not check, fast, loop, executor
- )
+ reformat_many(
+ sources=sources, fast=fast, write_back=write_back, mode=mode, report=report
+ )
+
+ if verbose or not quiet:
+ out("Oh no! 💥 💔 💥" if report.return_code else "All done! ✨ 🍰 ✨")
+ click.secho(str(report), err=True)
+ ctx.exit(report.return_code)
+
+
+def path_empty(
+ src: Tuple[str, ...], quiet: bool, verbose: bool, ctx: click.Context
+) -> None:
+ """
+ Exit if there is no `src` provided for formatting
+ """
+ if not src:
+ if verbose or not quiet:
+ out("No Path provided. Nothing to do 😴")
+ ctx.exit(0)
+
+
+def reformat_one(
+ src: Path, fast: bool, write_back: WriteBack, mode: Mode, report: "Report"
+) -> None:
+ """Reformat a single file under `src` without spawning child processes.
+
+ `fast`, `write_back`, and `mode` options are passed to
+ :func:`format_file_in_place` or :func:`format_stdin_to_stdout`.
+ """
+ try:
+ changed = Changed.NO
+ if not src.is_file() and str(src) == "-":
+ if format_stdin_to_stdout(fast=fast, write_back=write_back, mode=mode):
+ changed = Changed.YES
+ else:
+ cache: Cache = {}
+ if write_back != WriteBack.DIFF:
+ cache = read_cache(mode)
+ res_src = src.resolve()
+ if res_src in cache and cache[res_src] == get_cache_info(res_src):
+ changed = Changed.CACHED
+ if changed is not Changed.CACHED and format_file_in_place(
+ src, fast=fast, write_back=write_back, mode=mode
+ ):
+ changed = Changed.YES
+ if (write_back is WriteBack.YES and changed is not Changed.CACHED) or (
+ write_back is WriteBack.CHECK and changed is Changed.NO
+ ):
+ write_cache(cache, [src], mode)
+ report.done(src, changed)
+ except Exception as exc:
+ report.failed(src, str(exc))
+
+
+def reformat_many(
+ sources: Set[Path], fast: bool, write_back: WriteBack, mode: Mode, report: "Report"
+) -> None:
+ """Reformat multiple files using a ProcessPoolExecutor."""
+ executor: Executor
+ loop = asyncio.get_event_loop()
+ worker_count = os.cpu_count()
+ if sys.platform == "win32":
+ # Work around https://bugs.python.org/issue26903
+ worker_count = min(worker_count, 61)
+ try:
+ executor = ProcessPoolExecutor(max_workers=worker_count)
+ except OSError:
+ # we arrive here if the underlying system does not support multi-processing
+ # like in AWS Lambda, in which case we gracefully fallback to
+ # a ThreadPollExecutor with just a single worker (more workers would not do us
+ # any good due to the Global Interpreter Lock)
+ executor = ThreadPoolExecutor(max_workers=1)
+
+ try:
+ loop.run_until_complete(
+ schedule_formatting(
+ sources=sources,
+ fast=fast,
+ write_back=write_back,
+ mode=mode,
+ report=report,
+ loop=loop,
+ executor=executor,
)
- finally:
- loop.close()
- ctx.exit(return_code)
+ )
+ finally:
+ shutdown(loop)
+ if executor is not None:
+ executor.shutdown()
async def schedule_formatting(
- sources: List[Path],
- line_length: int,
- write_back: bool,
+ sources: Set[Path],
fast: bool,
- loop: BaseEventLoop,
+ write_back: WriteBack,
+ mode: Mode,
+ report: "Report",
+ loop: asyncio.AbstractEventLoop,
executor: Executor,
-) -> int:
+) -> None:
+ """Run formatting of `sources` in parallel using the provided `executor`.
+
+ (Use ProcessPoolExecutors for actual parallelism.)
+
+ `write_back`, `fast`, and `mode` options are passed to
+ :func:`format_file_in_place`.
+ """
+ cache: Cache = {}
+ if write_back != WriteBack.DIFF:
+ cache = read_cache(mode)
+ sources, cached = filter_cached(cache, sources)
+ for src in sorted(cached):
+ report.done(src, Changed.CACHED)
+ if not sources:
+ return
+
+ cancelled = []
+ sources_to_cache = []
+ lock = None
+ if write_back == WriteBack.DIFF:
+ # For diff output, we need locks to ensure we don't interleave output
+ # from different processes.
+ manager = Manager()
+ lock = manager.Lock()
tasks = {
- src: loop.run_in_executor(
- executor, format_file_in_place, src, line_length, fast, write_back
- )
- for src in sources
+ asyncio.ensure_future(
+ loop.run_in_executor(
+ executor, format_file_in_place, src, fast, mode, write_back, lock
+ )
+ ): src
+ for src in sorted(sources)
}
- await asyncio.wait(tasks.values())
- cancelled = []
- report = Report()
- for src, task in tasks.items():
- if not task.done():
- report.failed(src, 'timed out, cancelling')
- task.cancel()
- cancelled.append(task)
- elif task.exception():
- report.failed(src, str(task.exception()))
- else:
- report.done(src, task.result())
+ pending: Iterable["asyncio.Future[bool]"] = tasks.keys()
+ try:
+ loop.add_signal_handler(signal.SIGINT, cancel, pending)
+ loop.add_signal_handler(signal.SIGTERM, cancel, pending)
+ except NotImplementedError:
+ # There are no good alternatives for these on Windows.
+ pass
+ while pending:
+ done, _ = await asyncio.wait(pending, return_when=asyncio.FIRST_COMPLETED)
+ for task in done:
+ src = tasks.pop(task)
+ if task.cancelled():
+ cancelled.append(task)
+ elif task.exception():
+ report.failed(src, str(task.exception()))
+ else:
+ changed = Changed.YES if task.result() else Changed.NO
+ # If the file was written back or was successfully checked as
+ # well-formatted, store this information in the cache.
+ if write_back is WriteBack.YES or (
+ write_back is WriteBack.CHECK and changed is Changed.NO
+ ):
+ sources_to_cache.append(src)
+ report.done(src, changed)
if cancelled:
- await asyncio.wait(cancelled, timeout=2)
- out('All done! ✨ 🍰 ✨')
- click.echo(str(report))
- return report.return_code
+ await asyncio.gather(*cancelled, loop=loop, return_exceptions=True)
+ if sources_to_cache:
+ write_cache(cache, sources_to_cache, mode)
def format_file_in_place(
- src: Path, line_length: int, fast: bool, write_back: bool = False
+ src: Path,
+ fast: bool,
+ mode: Mode,
+ write_back: WriteBack = WriteBack.NO,
+ lock: Any = None, # multiprocessing.Manager().Lock() is some crazy proxy
) -> bool:
- """Format the file and rewrite if changed. Return True if changed."""
+ """Format file under `src` path. Return True if changed.
+
+ If `write_back` is DIFF, write a diff to stdout. If it is YES, write reformatted
+ code to the file.
+ `mode` and `fast` options are passed to :func:`format_file_contents`.
+ """
+ if src.suffix == ".pyi":
+ mode = replace(mode, is_pyi=True)
+
+ then = datetime.utcfromtimestamp(src.stat().st_mtime)
+ with open(src, "rb") as buf:
+ src_contents, encoding, newline = decode_bytes(buf.read())
try:
- contents, encoding = format_file(src, line_length=line_length, fast=fast)
+ dst_contents = format_file_contents(src_contents, fast=fast, mode=mode)
except NothingChanged:
return False
- if write_back:
- with open(src, "w", encoding=encoding) as f:
- f.write(contents)
+ if write_back == WriteBack.YES:
+ with open(src, "w", encoding=encoding, newline=newline) as f:
+ f.write(dst_contents)
+ elif write_back in (WriteBack.DIFF, WriteBack.COLOR_DIFF):
+ now = datetime.utcnow()
+ src_name = f"{src}\t{then} +0000"
+ dst_name = f"{src}\t{now} +0000"
+ diff_contents = diff(src_contents, dst_contents, src_name, dst_name)
+
+ if write_back == write_back.COLOR_DIFF:
+ diff_contents = color_diff(diff_contents)
+
+ with lock or nullcontext():
+ f = io.TextIOWrapper(
+ sys.stdout.buffer,
+ encoding=encoding,
+ newline=newline,
+ write_through=True,
+ )
+ f = wrap_stream_for_windows(f)
+ f.write(diff_contents)
+ f.detach()
+
return True
-def format_file(
- src: Path, line_length: int, fast: bool
-) -> Tuple[FileContent, Encoding]:
- """Reformats a file and returns its contents and encoding."""
- with tokenize.open(src) as src_buffer:
- src_contents = src_buffer.read()
- if src_contents.strip() == '':
- raise NothingChanged(src)
+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
+ if line.startswith("@@"):
+ line = "\033[36m" + line + "\033[0m" # cyan, reset
+ if 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.AnsiToWin32"]:
+ """
+ Wrap the stream in colorama's wrap_stream so colors are shown on Windows.
+
+ If `colorama` is not found, then no change is made. If `colorama` does
+ exist, then it handles the logic to determine whether or not to change
+ things.
+ """
+ try:
+ from colorama import initialise
+
+ # We set `strip=False` so that we can don't have to modify
+ # test_express_diff_with_color.
+ f = initialise.wrap_stream(
+ f, convert=None, strip=False, autoreset=False, wrap=True
+ )
+
+ # wrap_stream returns a `colorama.AnsiToWin32.AnsiToWin32` object
+ # which does not have a `detach()` method. So we fake one.
+ f.detach = lambda *args, **kwargs: None # type: ignore
+ except ImportError:
+ pass
+
+ return f
+
+
+def format_stdin_to_stdout(
+ fast: bool, *, write_back: WriteBack = WriteBack.NO, mode: Mode
+) -> bool:
+ """Format file on stdin. Return True if changed.
+
+ If `write_back` is YES, write reformatted code back to stdout. If it is DIFF,
+ write a diff to stdout. The `mode` argument is passed to
+ :func:`format_file_contents`.
+ """
+ then = datetime.utcnow()
+ src, encoding, newline = decode_bytes(sys.stdin.buffer.read())
+ dst = src
+ try:
+ dst = format_file_contents(src, fast=fast, mode=mode)
+ return True
+
+ except NothingChanged:
+ return False
+
+ finally:
+ f = io.TextIOWrapper(
+ sys.stdout.buffer, encoding=encoding, newline=newline, write_through=True
+ )
+ if write_back == WriteBack.YES:
+ f.write(dst)
+ elif write_back in (WriteBack.DIFF, WriteBack.COLOR_DIFF):
+ now = datetime.utcnow()
+ src_name = f"STDIN\t{then} +0000"
+ dst_name = f"STDOUT\t{now} +0000"
+ d = diff(src, dst, src_name, dst_name)
+ if write_back == WriteBack.COLOR_DIFF:
+ d = color_diff(d)
+ f = wrap_stream_for_windows(f)
+ f.write(d)
+ f.detach()
+
+
+def format_file_contents(src_contents: str, *, fast: bool, mode: Mode) -> FileContent:
+ """Reformat contents a file and return new contents.
+
+ If `fast` is False, additionally confirm that the reformatted code is
+ valid by calling :func:`assert_equivalent` and :func:`assert_stable` on it.
+ `mode` is passed to :func:`format_str`.
+ """
+ if src_contents.strip() == "":
+ raise NothingChanged
- dst_contents = format_str(src_contents, line_length=line_length)
+ dst_contents = format_str(src_contents, mode=mode)
if src_contents == dst_contents:
- raise NothingChanged(src)
+ raise NothingChanged
if not fast:
assert_equivalent(src_contents, dst_contents)
- assert_stable(src_contents, dst_contents, line_length=line_length)
- return dst_contents, src_buffer.encoding
+ assert_stable(src_contents, dst_contents, mode=mode)
+ return dst_contents
+
+def format_str(src_contents: str, *, mode: Mode) -> FileContent:
+ """Reformat a string and return new contents.
+
+ `mode` determines formatting options, such as how many characters per line are
+ allowed. Example:
+
+ >>> import black
+ >>> print(black.format_str("def f(arg:str='')->None:...", mode=Mode()))
+ def f(arg: str = "") -> None:
+ ...
+
+ A more complex example:
+ >>> print(
+ ... black.format_str(
+ ... "def f(arg:str='')->None: hey",
+ ... mode=black.Mode(
+ ... target_versions={black.TargetVersion.PY36},
+ ... line_length=10,
+ ... string_normalization=False,
+ ... is_pyi=False,
+ ... ),
+ ... ),
+ ... )
+ def f(
+ arg: str = '',
+ ) -> None:
+ hey
-def format_str(src_contents: str, line_length: int) -> FileContent:
- """Reformats a string and returns new contents."""
- src_node = lib2to3_parse(src_contents)
- dst_contents = ""
- comments: List[Line] = []
- lines = LineGenerator()
- elt = EmptyLineTracker()
+ """
+ src_node = lib2to3_parse(src_contents.lstrip(), mode.target_versions)
+ dst_contents = []
+ future_imports = get_future_imports(src_node)
+ if mode.target_versions:
+ versions = mode.target_versions
+ else:
+ versions = detect_target_versions(src_node)
+ normalize_fmt_off(src_node)
+ lines = LineGenerator(
+ remove_u_prefix="unicode_literals" in future_imports
+ or supports_feature(versions, Feature.UNICODE_LITERALS),
+ is_pyi=mode.is_pyi,
+ normalize_strings=mode.string_normalization,
+ )
+ elt = EmptyLineTracker(is_pyi=mode.is_pyi)
empty_line = Line()
after = 0
+ split_line_features = {
+ feature
+ for feature in {Feature.TRAILING_COMMA_IN_CALL, Feature.TRAILING_COMMA_IN_DEF}
+ if supports_feature(versions, feature)
+ }
for current_line in lines.visit(src_node):
- for _ in range(after):
- dst_contents += str(empty_line)
+ dst_contents.append(str(empty_line) * after)
before, after = elt.maybe_empty_lines(current_line)
- for _ in range(before):
- dst_contents += str(empty_line)
- if not current_line.is_comment:
- for comment in comments:
- dst_contents += str(comment)
- comments = []
- for line in split_line(current_line, line_length=line_length):
- dst_contents += str(line)
- else:
- comments.append(current_line)
- for comment in comments:
- dst_contents += str(comment)
- return dst_contents
+ dst_contents.append(str(empty_line) * before)
+ for line in transform_line(
+ current_line,
+ line_length=mode.line_length,
+ normalize_strings=mode.string_normalization,
+ features=split_line_features,
+ ):
+ dst_contents.append(str(line))
+ return "".join(dst_contents)
+
+
+def decode_bytes(src: bytes) -> Tuple[FileContent, Encoding, NewLine]:
+ """Return a tuple of (decoded_contents, encoding, newline).
+
+ `newline` is either CRLF or LF but `decoded_contents` is decoded with
+ universal newlines (i.e. only contains LF).
+ """
+ srcbuf = io.BytesIO(src)
+ encoding, lines = tokenize.detect_encoding(srcbuf.readline)
+ if not lines:
+ return "", encoding, "\n"
+
+ newline = "\r\n" if b"\r\n" == lines[0][-2:] else "\n"
+ srcbuf.seek(0)
+ with io.TextIOWrapper(srcbuf, encoding) as tiow:
+ 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) -> Node:
+def lib2to3_parse(src_txt: str, target_versions: Iterable[TargetVersion] = ()) -> Node:
"""Given a string with source, return the lib2to3 Node."""
- grammar = pygram.python_grammar_no_print_statement
- drv = driver.Driver(grammar, pytree.convert)
- if src_txt[-1] != '\n':
- nl = '\r\n' if '\r\n' in src_txt[:1024] else '\n'
- src_txt += nl
- try:
- result = drv.parse_string(src_txt, True)
- except ParseError as pe:
- lineno, column = pe.context[1]
- lines = src_txt.splitlines()
+ if src_txt[-1:] != "\n":
+ src_txt += "\n"
+
+ for grammar in get_grammars(set(target_versions)):
+ drv = driver.Driver(grammar, pytree.convert)
try:
- faulty_line = lines[lineno - 1]
- except IndexError:
- faulty_line = "<line number missing in source>"
- raise ValueError(f"Cannot parse: {lineno}:{column}: {faulty_line}") from None
+ 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 code
-T = TypeVar('T')
-
-
class Visitor(Generic[T]):
- """Basic lib2to3 visitor that yields things on visiting."""
+ """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 = type_repr(node.type)
- yield from getattr(self, f'visit_{name}', self.visit_default)(node)
+ 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 = attrib(default=0)
+ tree_depth: int = 0
def visit_default(self, node: LN) -> Iterator[T]:
- indent = ' ' * (2 * self.tree_depth)
+ indent = " " * (2 * self.tree_depth)
if isinstance(node, Node):
_type = type_repr(node.type)
- out(f'{indent}{_type}', fg='yellow')
+ 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)
+ 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)
+ 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)
+ 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`.
-KEYWORDS = set(keyword.kwlist)
-WHITESPACE = {token.DEDENT, token.INDENT, token.NEWLINE}
-FLOW_CONTROL = {'return', 'raise', 'break', 'continue'}
-STATEMENT = {
+ 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.funcdef,
syms.classdef,
}
-STANDALONE_COMMENT = 153
-LOGIC_OPERATORS = {'and', 'or'}
-COMPARATORS = {
+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.LESSEQUAL,
token.GREATEREQUAL,
}
-MATH_OPERATORS = {
+MATH_OPERATORS: Final = {
+ token.VBAR,
+ token.CIRCUMFLEX,
+ token.AMPER,
+ token.LEFTSHIFT,
+ token.RIGHTSHIFT,
token.PLUS,
token.MINUS,
token.STAR,
token.SLASH,
- token.VBAR,
- token.AMPER,
+ token.DOUBLESLASH,
token.PERCENT,
- token.CIRCUMFLEX,
- token.LEFTSHIFT,
- token.RIGHTSHIFT,
+ token.AT,
+ token.TILDE,
token.DOUBLESTAR,
- token.DOUBLESLASH,
}
-COMPREHENSION_PRIORITY = 20
-COMMA_PRIORITY = 10
-LOGIC_PRIORITY = 5
-STRING_PRIORITY = 4
-COMPARATOR_PRIORITY = 3
-MATH_PRIORITY = 1
+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:
- depth: int = attrib(default=0)
- bracket_match: Dict[Tuple[Depth, NodeType], Leaf] = attrib(default=Factory(dict))
- delimiters: Dict[LeafID, Priority] = attrib(default=Factory(dict))
- previous: Optional[Leaf] = attrib(default=None)
+ """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)
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
opening_bracket = self.bracket_match.pop((self.depth, leaf.type))
- leaf.opening_bracket = opening_bracket # type: ignore
- leaf.bracket_depth = self.depth # type: ignore
+ leaf.opening_bracket = opening_bracket
+ leaf.bracket_depth = self.depth
if self.depth == 0:
- delim = is_delimiter(leaf)
- if delim:
- self.delimiters[id(leaf)] = delim
- elif self.previous is not None:
- if leaf.type == token.STRING and self.previous.type == token.STRING:
- self.delimiters[id(self.previous)] = STRING_PRIORITY
- elif (
- leaf.type == token.NAME and
- leaf.value == 'for' and
- leaf.parent and
- leaf.parent.type in {syms.comp_for, syms.old_comp_for}
- ):
- self.delimiters[id(self.previous)] = COMPREHENSION_PRIORITY
- elif (
- leaf.type == token.NAME and
- leaf.value == 'if' and
- leaf.parent and
- leaf.parent.type in {syms.comp_if, syms.old_comp_if}
- ):
- self.delimiters[id(self.previous)] = COMPREHENSION_PRIORITY
+ 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
self.previous = leaf
+ self.maybe_increment_lambda_arguments(leaf)
+ self.maybe_increment_for_loop_variable(leaf)
def any_open_brackets(self) -> bool:
- """Returns True if there is an yet unmatched open bracket on the line."""
+ """Return True if there is an yet unmatched open bracket on the line."""
return bool(self.bracket_match)
- def max_priority(self, exclude: Iterable[LeafID] =()) -> int:
- """Returns the highest priority of a delimiter found on the line.
+ 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_delimiter()` returns.
+ 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`.
-@dataclass
-class Line:
- depth: int = attrib(default=0)
- leaves: List[Leaf] = attrib(default=Factory(list))
- comments: Dict[LeafID, Leaf] = attrib(default=Factory(dict))
- bracket_tracker: BracketTracker = attrib(default=Factory(BracketTracker))
- inside_brackets: bool = attrib(default=False)
- has_for: bool = attrib(default=False)
- _for_loop_variable: bool = attrib(default=False, init=False)
+ If no `priority` is passed, defaults to max priority on the line.
+ """
+ if not self.delimiters:
+ return 0
- def append(self, leaf: Leaf, preformatted: bool = False) -> None:
- has_value = leaf.value.strip()
- if not has_value:
- return
+ priority = priority or self.max_delimiter_priority()
+ return sum(1 for p in self.delimiters.values() if p == priority)
- 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)
- if self.inside_brackets or not preformatted:
- self.maybe_decrement_after_for_loop_variable(leaf)
- self.bracket_tracker.mark(leaf)
- self.maybe_remove_trailing_comma(leaf)
- self.maybe_increment_for_loop_variable(leaf)
- if self.maybe_adapt_standalone_comment(leaf):
- return
+ def maybe_increment_for_loop_variable(self, leaf: Leaf) -> bool:
+ """In a for loop, or comprehension, the variables are often unpacks.
- if not self.append_comment(leaf):
- self.leaves.append(leaf)
+ 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))
+
+
+@dataclass
+class Line:
+ """Holds leaves and comments. Can be printed with `str(line)`."""
+
+ 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_explode: bool = False
+
+ 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)
+ self.maybe_remove_trailing_comma(leaf)
+ 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:
- return bool(self) and self.leaves[0].type == STANDALONE_COMMENT
+ """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'
+ 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_collection_with_optional_trailing_comma(self) -> bool:
+ """Is this line a collection literal with a trailing comma that's optional?
+
+ Note that the trailing comma in a 1-tuple is not optional.
+ """
+ if not self.leaves or len(self.leaves) < 4:
+ return False
+
+ # Look for and address a trailing colon.
+ if self.leaves[-1].type == token.COLON:
+ closer = self.leaves[-2]
+ close_index = -2
+ else:
+ closer = self.leaves[-1]
+ close_index = -1
+ if closer.type not in CLOSING_BRACKETS or self.inside_brackets:
+ return False
+
+ if closer.type == token.RPAR:
+ # Tuples require an extra check, because if there's only
+ # one element in the tuple removing the comma unmakes the
+ # tuple.
+ #
+ # We also check for parens before looking for the trailing
+ # comma because in some cases (eg assigning a dict
+ # literal) the literal gets wrapped in temporary parens
+ # during parsing. This case is covered by the
+ # collections.py test data.
+ opener = closer.opening_bracket
+ for _open_index, leaf in enumerate(self.leaves):
+ if leaf is opener:
+ break
+
+ else:
+ # Couldn't find the matching opening paren, play it safe.
+ return False
+
+ commas = 0
+ comma_depth = self.leaves[close_index - 1].bracket_depth
+ for leaf in self.leaves[_open_index + 1 : close_index]:
+ if leaf.bracket_depth == comma_depth and leaf.type == token.COMMA:
+ commas += 1
+ if commas > 1:
+ # We haven't looked yet for the trailing comma because
+ # we might also have caught noop parens.
+ return self.leaves[close_index - 1].type == token.COMMA
+
+ elif commas == 1:
+ return False # it's either a one-tuple or didn't have a trailing comma
+
+ if self.leaves[close_index - 1].type in CLOSING_BRACKETS:
+ close_index -= 1
+ closer = self.leaves[close_index]
+ if closer.type == token.RPAR:
+ # TODO: this is a gut feeling. Will we ever see this?
+ return False
+
+ if self.leaves[close_index - 1].type != token.COMMA:
+ return False
+
+ return True
+
@property
def is_def(self) -> bool:
- """Also returns True for async defs."""
+ """Is this a function definition? (Also returns True for async defs.)"""
try:
first_leaf = self.leaves[0]
except IndexError:
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.NAME and
- first_leaf.value == 'async' and
- second_leaf is not None and
- second_leaf.type == token.NAME and
- second_leaf.value == 'def'
- )
+ 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_flow_control(self) -> bool:
+ 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
- self.leaves[0].type == token.NAME and
- self.leaves[0].value in FLOW_CONTROL
+ 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_yield(self) -> bool:
+ def is_triple_quoted_string(self) -> bool:
+ """Is the line a triple quoted string?"""
return (
- bool(self) and
- self.leaves[0].type == token.NAME and
- self.leaves[0].value == 'yield'
+ bool(self)
+ and self.leaves[0].type == token.STRING
+ and self.leaves[0].value.startswith(('"""', "'''"))
)
- def maybe_remove_trailing_comma(self, closing: Leaf) -> bool:
- if not (
- self.leaves and
- self.leaves[-1].type == token.COMMA and
- closing.type in CLOSING_BRACKETS
- ):
- return False
+ 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
- if closing.type == token.RSQB or closing.type == token.RBRACE:
- self.leaves.pop()
- return True
-
- # For parens let's check if it's safe to remove the comma. If the
- # trailing one is the only one, we might mistakenly change a tuple
- # into a different type by removing the comma.
- depth = closing.bracket_depth + 1 # type: ignore
- commas = 0
- opening = closing.opening_bracket # type: ignore
- for _opening_index, leaf in enumerate(self.leaves):
- if leaf is opening:
- break
+ return False
- else:
+ 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
- for leaf in self.leaves[_opening_index + 1:]:
- if leaf is closing:
- break
+ # 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
- bracket_depth = leaf.bracket_depth # type: ignore
- if bracket_depth == depth and leaf.type == token.COMMA:
- commas += 1
- if commas > 1:
- self.leaves.pop()
- return True
+ comment_seen = True
return False
- 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, we will increase
- the depth of tokens between `for` and `in`.
- """
- if leaf.type == token.NAME and leaf.value == 'for':
- self.has_for = True
- self.bracket_tracker.depth += 1
- self._for_loop_variable = True
- return True
-
- return False
+ def contains_unsplittable_type_ignore(self) -> bool:
+ if not self.leaves:
+ 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_variable and leaf.type == token.NAME and leaf.value == 'in':
- self.bracket_tracker.depth -= 1
- self._for_loop_variable = False
- return True
+ # 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((l.lineno for l in self.leaves if l.lineno != 0), 0)
+ last_line = next((l.lineno for l in reversed(self.leaves) if l.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 maybe_adapt_standalone_comment(self, comment: Leaf) -> bool:
- """Hack a standalone comment to act as a trailing comment for line splitting.
+ def contains_multiline_strings(self) -> bool:
+ return any(is_multiline_string(leaf) for leaf in self.leaves)
- If this line has brackets and a standalone `comment`, we need to adapt
- it to be able to still reformat the line.
+ def maybe_remove_trailing_comma(self, closing: Leaf) -> bool:
+ """Remove trailing comma if there is one and it's safe."""
+ if not (self.leaves and self.leaves[-1].type == token.COMMA):
+ return False
- This is not perfect, the line to which the standalone comment gets
- appended will appear "too long" when splitting.
- """
+ # We remove trailing commas only in the case of importing a
+ # single name from a module.
if not (
- comment.type == STANDALONE_COMMENT and
- self.bracket_tracker.any_open_brackets()
+ self.leaves
+ and self.is_import
+ and len(self.leaves) > 4
+ and self.leaves[-1].type == token.COMMA
+ and closing.type in CLOSING_BRACKETS
+ and self.leaves[-4].type == token.NAME
+ and (
+ # regular `from foo import bar,`
+ self.leaves[-4].value == "import"
+ # `from foo import (bar as baz,)
+ or (
+ len(self.leaves) > 6
+ and self.leaves[-6].value == "import"
+ and self.leaves[-3].value == "as"
+ )
+ # `from foo import bar as baz,`
+ or (
+ len(self.leaves) > 5
+ and self.leaves[-5].value == "import"
+ and self.leaves[-3].value == "as"
+ )
+ )
+ and closing.type == token.RPAR
):
return False
- comment.type = token.COMMENT
- comment.prefix = '\n' + ' ' * (self.depth + 1)
- return self.append_comment(comment)
+ self.remove_trailing_comma()
+ return True
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
- try:
- after = id(self.last_non_delimiter())
- except LookupError:
+ if not self.leaves:
comment.type = STANDALONE_COMMENT
- comment.prefix = ''
+ comment.prefix = ""
return False
- else:
- if after in self.comments:
- self.comments[after].value += str(comment)
- else:
- self.comments[after] = comment
- return True
+ 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
- def last_non_delimiter(self) -> Leaf:
- for i in range(len(self.leaves)):
- last = self.leaves[-i - 1]
- if not is_delimiter(last):
- return last
+ if isinstance(subscript_start, Node):
+ if subscript_start.type == syms.listmaker:
+ return False
- raise LookupError("No non-delimiters found")
+ 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(
+ depth=self.depth,
+ inside_brackets=self.inside_brackets,
+ should_explode=self.should_explode,
+ )
def __str__(self) -> str:
+ """Render the line."""
if not self:
- return '\n'
+ return "\n"
- indent = ' ' * self.depth
+ indent = " " * self.depth
leaves = iter(self.leaves)
first = next(leaves)
- res = f'{first.prefix}{indent}{first.value}'
+ res = f"{first.prefix}{indent}{first.value}"
for leaf in leaves:
res += str(leaf)
- for comment in self.comments.values():
+ for comment in itertools.chain.from_iterable(self.comments.values()):
res += str(comment)
- return res + '\n'
+
+ return res + "\n"
def __bool__(self) -> bool:
+ """Return True if the line has leaves or comments."""
return bool(self.leaves or self.comments)
"""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.
+ 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.
"""
- previous_line: Optional[Line] = attrib(default=None)
- previous_after: int = attrib(default=0)
- previous_defs: List[int] = attrib(default=Factory(list))
+
+ 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]:
- """Returns the number of extra empty lines before and after the `current_line`.
+ """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), as well as providing an extra empty line after flow
- control keywords to make them more prominent.
+ 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]:
- before = 0
+ 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()
- before = (1 if depth else 2) - self.previous_after
- is_decorator = current_line.is_decorator
- if is_decorator or current_line.is_def or current_line.is_class:
- if not is_decorator:
- self.previous_defs.append(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 and self.previous_line.is_decorator:
- # Don't insert empty lines between decorators.
- return 0, 0
-
- newlines = 2
- if current_line.depth:
- newlines -= 1
- newlines -= self.previous_after
- return newlines, 0
-
- if current_line.is_flow_control:
- return before, 1
+ 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
+ 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_yield and
- (not current_line.is_yield or depth != self.previous_line.depth)
+ self.previous_line
+ and self.previous_line.is_class
+ and current_line.is_triple_quoted_string
):
- return (before or 1), 0
+ 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:
+ 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 and not self.previous_line.is_def:
+ # Blank line between a block of functions 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]):
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.
"""
- current_line: Line = attrib(default=Factory(Line))
- standalone_comments: List[Leaf] = attrib(default=Factory(list))
+
+ is_pyi: bool = False
+ normalize_strings: bool = True
+ current_line: Line = field(default_factory=Line)
+ remove_u_prefix: bool = False
def line(self, indent: int = 0) -> Iterator[Line]:
"""Generate a line.
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 self.current_line.bracket_tracker.any_open_brackets():
+ if any_open_brackets:
# any comment within brackets is subject to splitting
self.current_line.append(comment)
elif comment.type == token.COMMENT:
yield from self.line()
else:
- # regular standalone comment, to be processed later (see
- # docstring in `generate_comments()`
- self.standalone_comments.append(comment)
- normalize_prefix(node)
- if node.type not in WHITESPACE:
- for comment in self.standalone_comments:
+ # regular standalone comment
yield from self.line()
self.current_line.append(comment)
yield from self.line()
- self.standalone_comments = []
+ normalize_prefix(node, inside_brackets=any_open_brackets)
+ if self.normalize_strings 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_suite(self, node: Node) -> Iterator[Line]:
- """Body of a statement after a colon."""
- children = iter(node.children)
- # Process newline before indenting. It might contain an inline
- # comment that should go right after the colon.
- newline = next(children)
- yield from self.visit(newline)
+ 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)
- for child in children:
- yield from self.visit(child)
+ 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]) -> Iterator[Line]:
+ def visit_stmt(
+ self, node: Node, keywords: Set[str], parens: Set[str]
+ ) -> Iterator[Line]:
"""Visit a statement.
- The relevant Python language keywords for this statement are NAME leaves
- within it.
+ 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.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]:
- """A statement without nested statements."""
+ """Visit a statement without nested statements."""
is_suite_like = node.parent and node.parent.type in STATEMENT
if is_suite_like:
- yield from self.line(+1)
- yield from self.visit_default(node)
- yield from self.line(-1)
+ if self.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:
- yield from self.line()
+ if not self.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.NAME and child.value == 'async': # type: ignore
+ if child.type == token.ASYNC:
break
internal_stmt = next(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 __attrs_post_init__(self) -> None:
+ 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]:
+ # Check if it's a docstring
+ if prev_siblings_are(
+ leaf.parent, [None, token.NEWLINE, token.INDENT, syms.simple_stmt]
+ ) and is_multiline_string(leaf):
+ prefix = " " * self.current_line.depth
+ docstring = fix_docstring(leaf.value[3:-3], prefix)
+ leaf.value = leaf.value[0:3] + docstring + leaf.value[-3:]
+ normalize_string_quotes(leaf)
+
+ yield from self.visit_default(leaf)
+
+ def __post_init__(self) -> None:
"""You are in a twisty little maze of passages."""
v = self.visit_stmt
- self.visit_if_stmt = partial(v, keywords={'if', 'else', 'elif'})
- self.visit_while_stmt = partial(v, keywords={'while', 'else'})
- self.visit_for_stmt = partial(v, keywords={'for', 'else'})
- self.visit_try_stmt = partial(v, keywords={'try', 'except', 'else', 'finally'})
- self.visit_except_clause = partial(v, keywords={'except'})
- self.visit_funcdef = partial(v, keywords={'def'})
- self.visit_with_stmt = partial(v, keywords={'with'})
- self.visit_classdef = partial(v, keywords={'class'})
+ Ø: 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=Ø
+ )
+ self.visit_except_clause = partial(v, keywords={"except"}, parens=Ø)
+ self.visit_with_stmt = partial(v, keywords={"with"}, parens=Ø)
+ self.visit_funcdef = partial(v, keywords={"def"}, parens=Ø)
+ self.visit_classdef = partial(v, keywords={"class"}, parens=Ø)
+ self.visit_expr_stmt = partial(v, keywords=Ø, parens=ASSIGNMENTS)
+ self.visit_return_stmt = partial(v, keywords={"return"}, parens={"return"})
+ self.visit_import_from = partial(v, keywords=Ø, parens={"import"})
+ self.visit_del_stmt = partial(v, keywords=Ø, 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) -> str:
- """Return whitespace prefix if needed for the given `leaf`."""
- NO = ''
- SPACE = ' '
- DOUBLESPACE = ' '
+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 == token.COLON:
- return NO
-
- if t == token.COMMA:
- return NO
-
- if t == token.RPAR:
+ if t in ALWAYS_NO_SPACE:
return NO
if t == token.COMMENT:
return DOUBLESPACE
- if t == STANDALONE_COMMENT:
- return NO
-
- if t in CLOSING_BRACKETS:
+ 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
- assert p is not None, f"INTERNAL ERROR: hand-made leaf without parent: {leaf!r}"
prev = leaf.prev_sibling
if not prev:
prevp = preceding_leaf(p)
if not prevp or prevp.type in OPENING_BRACKETS:
return NO
- if prevp.type == token.EQUAL:
- if prevp.parent and prevp.parent.type in {
- syms.typedargslist,
- syms.varargslist,
- syms.parameters,
- syms.arglist,
- syms.argument,
- }:
+ if t == token.COLON:
+ if prevp.type == token.COLON:
return NO
- elif prevp.type == token.DOUBLESTAR:
- if prevp.parent and prevp.parent.type in {
- syms.typedargslist,
- syms.varargslist,
- syms.parameters,
- syms.arglist,
- syms.dictsetmaker,
- }:
+ elif prevp.type != token.COMMA and not complex_subscript:
return NO
- elif prevp.type == token.COLON:
- if prevp.parent and prevp.parent.type == syms.subscript:
+ 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.parent and prevp.parent.type == syms.factor:
+ 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 prev.type in OPENING_BRACKETS:
if p.type in {syms.parameters, syms.arglist}:
# untyped function signatures or calls
- if t == token.RPAR:
- return NO
-
if not prev or prev.type != token.COMMA:
return NO
- if p.type == syms.varargslist:
+ elif p.type == syms.varargslist:
# lambdas
- if t == token.RPAR:
- return NO
-
if prev and prev.type != token.COMMA:
return NO
if not prevp or prevp.type == token.LPAR:
return NO
- elif prev.type == token.EQUAL or prev.type == token.DOUBLESTAR:
+ elif prev.type in {token.EQUAL} | VARARGS_SPECIALS:
return NO
elif p.type == syms.decorator:
if prev and prev.type == token.LPAR:
return NO
- elif p.type == syms.subscript:
+ elif p.type in {syms.subscript, syms.sliceop}:
# indexing
- if not prev or prev.type == token.COLON:
+ 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:
# dots, but not the first one.
return NO
- elif (
- p.type == syms.listmaker or
- p.type == syms.testlist_gexp or
- p.type == syms.subscriptlist
- ):
- # list interior, including unpacking
- if not prev:
- return NO
-
elif p.type == syms.dictsetmaker:
- # dict and set interior, including unpacking
- if not prev:
- return NO
-
- if prev.type == token.DOUBLESTAR:
+ # dict unpacking
+ if prev and prev.type == token.DOUBLESTAR:
return NO
- elif p.type == syms.factor or p.type == syms.star_expr:
+ elif p.type in {syms.factor, syms.star_expr}:
# unary ops
if not prev:
prevp = preceding_leaf(p)
prevp_parent = prevp.parent
assert prevp_parent is not None
if prevp.type == token.COLON and prevp_parent.type in {
- syms.subscript, syms.sliceop
+ syms.subscript,
+ syms.sliceop,
}:
return NO
elif prevp.type == token.EQUAL and prevp_parent.type == syms.argument:
return NO
- elif t == token.NAME or t == token.NUMBER:
+ elif t in {token.NAME, token.NUMBER, token.STRING}:
return NO
elif p.type == syms.import_from:
return NO
elif t == token.NAME:
- if v == 'import':
+ if v == "import":
return SPACE
if prev and prev.type == token.DOT:
def preceding_leaf(node: Optional[LN]) -> Optional[Leaf]:
- """Returns the first leaf that precedes `node`, if any."""
+ """Return the first leaf that precedes `node`, if any."""
while node:
res = node.prev_sibling
if res:
return None
-def is_delimiter(leaf: Leaf) -> int:
- """Returns the priority of the `leaf` delimiter. Returns 0 if not delimiter.
+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])
- Higher numbers are higher priority.
- """
- if leaf.type == token.COMMA:
- return COMMA_PRIORITY
- if leaf.type == token.NAME and leaf.value in LOGIC_OPERATORS:
- return LOGIC_PRIORITY
+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
- if leaf.type in COMPARATORS:
- return COMPARATOR_PRIORITY
- if (
- leaf.type in MATH_OPERATORS and
- leaf.parent and
- leaf.parent.type not in {syms.factor, syms.star_expr}
- ):
- return MATH_PRIORITY
+def container_of(leaf: Leaf) -> LN:
+ """Return `leaf` or one of its ancestors that is the topmost container of it.
- return 0
+ 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
-def generate_comments(leaf: Leaf) -> Iterator[Leaf]:
- """Cleans the prefix of the `leaf` and generates comments from it, if any.
+ if parent.type == syms.file_input:
+ break
- 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.
+ if parent.prev_sibling is not None and parent.prev_sibling.type in BRACKETS:
+ break
- 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.
+ container = parent
+ return container
- 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.
- """
- if not leaf.prefix:
- return
+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.
- if '#' not in leaf.prefix:
- return
+ The delimiter priorities returned here are from those delimiters that would
+ cause a line break after themselves.
- before_comment, content = leaf.prefix.split('#', 1)
- content = content.rstrip()
- if content and (content[0] not in {' ', '!', '#'}):
- content = ' ' + content
- is_standalone_comment = (
- '\n' in before_comment or '\n' in content or leaf.type == token.DEDENT
- )
- if not is_standalone_comment:
- # simple trailing comment
- yield Leaf(token.COMMENT, value='#' + content)
- return
+ Higher numbers are higher priority.
+ """
+ if leaf.type == token.COMMA:
+ return COMMA_PRIORITY
- for line in ('#' + content).split('\n'):
- line = line.lstrip()
- if not line.startswith('#'):
- continue
+ return 0
- yield Leaf(STANDALONE_COMMENT, line)
+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.
-def split_line(line: Line, line_length: int, inner: bool = False) -> Iterator[Line]:
- """Splits a `line` into potentially many lines.
+ 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_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(prefix.split("\n")):
+ 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:]
+ if content and content[0] not in " !:#'%":
+ content = " " + content
+ return "#" + content
+
+
+def transform_line(
+ line: Line,
+ line_length: int,
+ normalize_strings: bool,
+ 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.
- `inner` signifies that there were a pair of brackets somewhere around the
- current `line`, possibly transitively. This means we can fallback to splitting
- by delimiters if the LHS/RHS don't yield any results.
+
+ `features` are syntactical features that may be used in the output.
"""
- line_str = str(line).strip('\n')
- if len(line_str) <= line_length and '\n' not in line_str:
+ if line.is_comment:
yield line
return
- if line.is_def:
- split_funcs = [left_hand_split]
- elif line.inside_brackets:
- split_funcs = [delimiter_split]
- if '\n' not in line_str:
- # Only attempt RHS if we don't have multiline strings or comments
- # on this line.
- split_funcs.append(right_hand_split)
+ line_str = line_to_string(line)
+
+ def init_st(ST: Type[StringTransformer]) -> StringTransformer:
+ """Initialize StringTransformer"""
+ return ST(line_length, normalize_strings)
+
+ 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_explode
+ and not line.is_collection_with_optional_trailing_comma
+ and (
+ is_line_short_enough(line, line_length=line_length, line_str=line_str)
+ or line.contains_unsplittable_type_ignore()
+ )
+ and not (line.contains_standalone_comments() and line.inside_brackets)
+ ):
+ # Only apply basic string preprocessing, since lines shouldn't be split here.
+ transformers = [string_merge, string_paren_strip]
+ elif line.is_def:
+ transformers = [left_hand_split]
else:
- split_funcs = [right_hand_split]
- for split_func in split_funcs:
+
+ def rhs(line: Line, features: Collection[Feature]) -> Iterator[Line]:
+ for omit in generate_trailers_to_omit(line, line_length):
+ lines = list(right_hand_split(line, line_length, features, omit=omit))
+ if is_line_short_enough(lines[0], line_length=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.
+ # line_length=1 here was historically a bug that somehow became a feature.
+ # See #762 and #781 for the full story.
+ yield from right_hand_split(line, line_length=1, features=features)
+
+ if line.inside_brackets:
+ transformers = [
+ string_merge,
+ string_paren_strip,
+ delimiter_split,
+ standalone_comment_split,
+ string_split,
+ string_paren_wrap,
+ rhs,
+ ]
+ else:
+ transformers = [
+ string_merge,
+ string_paren_strip,
+ string_split,
+ string_paren_wrap,
+ 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.
result: List[Line] = []
try:
- for l in split_func(line):
- if str(l).strip('\n') == line_str:
- raise CannotSplit("Split function returned an unchanged result")
+ for l in transform(line, features):
+ if str(l).strip("\n") == line_str:
+ raise CannotTransform(
+ "Line transformer returned an unchanged result"
+ )
+
+ result.extend(
+ transform_line(
+ l,
+ line_length=line_length,
+ normalize_strings=normalize_strings,
+ features=features,
+ )
+ )
+ 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 requirments, 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
+
+ @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 at most one substring
+ has inline comments AND none of those inline comments are pragmas AND
+ the set of all substring prefixes is either of length 1 or equal to
+ {"", "f"} AND none of the substrings are raw strings (i.e. are prefixed
+ with 'r').
+ 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
+ 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 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.
+ """
+ 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 RPAR is NOT followed by an attribute access (i.e. a dot).
+
+ 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
+
+ # 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)
+
+ # 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 a '.' symbol.
+ if is_valid_index(next_idx + 1) and LL[next_idx + 1].type == 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."
+ )
+
+ new_line = line.clone()
+ new_line.comments = line.comments.copy()
+
+ append_leaves(new_line, line, LL[: string_idx - 1])
+
+ 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.
+ for leaf in LL[: p_idx + 1]:
+ offset += len(str(leaf))
+
+ 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).
+
+ 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"""
+ (?<!\{)\{
+ (?:
+ [^\{\}]
+ | \{\{
+ | \}\}
+ )+?
+ (?<!\})(?:\}\})*\}(?!\})
+ """
+
+ 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
+ # containes 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 algorthmically 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_big_enough = (
+ len(string[i:]) >= self.MIN_SUBSTR_SIZE
+ and len(string[:i]) >= self.MIN_SUBSTR_SIZE
+ )
+ return is_space 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 = None
+ string_idx = string_idx or self._return_match(LL)
+ string_idx = string_idx or self._else_match(LL)
+ string_idx = string_idx or self._assert_match(LL)
+ string_idx = string_idx or self._assign_match(LL)
+ string_idx = string_idx 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 = len(LL) - 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(
+ depth=line.depth + 1,
+ inside_brackets=True,
+ should_explode=line.should_explode,
+ )
+ 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-existant, 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 paramater 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]) -> 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 attatched 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:
+ assert old_leaf in old_line.leaves
+
+ new_leaf = Leaf(old_leaf.type, old_leaf.value)
+ replace_child(old_leaf, new_leaf)
+ new_line.append(new_leaf)
+
+ 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 (
+ # the body shouldn't be exploded
+ not body.should_explode
+ # 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 = {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(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(l.type == token.COMMA for l 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:
+ leaves.insert(i + 1, Leaf(token.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:
+ result.should_explode = should_explode(result, opening_bracket)
+ 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 l in split_func(line, features):
+ normalize_prefix(l.leaves[0], inside_brackets=True)
+ yield l
+
+ 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(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(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(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
+ ):
+ current_line.append(Leaf(token.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(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(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"):
+ # Change hex literals to upper case.
+ before, after = text[:2], text[2:]
+ text = f"{before}{after.upper()}"
+ elif "e" in text:
+ 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)
+ text = f"{before}e{sign}{after}"
+ elif text.endswith(("j", "l")):
+ number = text[:-1]
+ suffix = text[-1]
+ # Capitalize in "2L" because "l" looks too similar to "1".
+ if suffix == "l":
+ suffix = "L"
+ text = f"{format_float_or_int_string(number)}{suffix}"
+ else:
+ text = format_float_or_int_string(text)
+ leaf.value = text
+
+
+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 is_walrus_assignment(child):
+ continue
+
+ 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 in FMT_OFF:
+ # 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.type != STANDALONE_COMMENT:
+ prev = preceding_leaf(leaf)
+ if prev and prev.type not in WHITESPACE:
+ continue
+
+ ignored_nodes = list(generate_ignored_nodes(leaf))
+ 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 = (
+ comment.value + "\n" + "".join(str(n) for n in ignored_nodes)
+ )
+ 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
+
+ previous_consumed = comment.consumed
+
+ return False
+
+
+def generate_ignored_nodes(leaf: Leaf) -> Iterator[LN]:
+ """Starting from the container of `leaf`, generate all leaves until `# fmt: on`.
+
+ Stops at the end of the block.
+ """
+ container: Optional[LN] = container_of(leaf)
+ 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
+
+ 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 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_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_explode(line: Line, opening_bracket: Leaf) -> bool:
+ """Should `line` immediately be split with `delimiter_split()` after RHS?"""
+
+ if not (
+ opening_bracket.parent
+ and opening_bracket.parent.type in {syms.atom, syms.import_from}
+ and opening_bracket.value in "[{("
+ ):
+ return False
+
+ try:
+ last_leaf = line.leaves[-1]
+ exclude = {id(last_leaf)} if last_leaf.type == token.COMMA else set()
+ max_priority = line.bracket_tracker.max_delimiter_priority(exclude=exclude)
+ except (IndexError, ValueError):
+ return False
+
+ return max_priority == COMMA_PRIORITY
+
+
+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;
+ """
+ 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 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
- result.extend(split_line(l, line_length=line_length, inner=True))
- except CannotSplit as cs:
- continue
- else:
- yield from result
- break
+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]
+ }
- else:
- yield line
+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.
-def left_hand_split(line: Line) -> Iterator[Line]:
- """Split line into many lines, starting with the first matching bracket pair.
+ Brackets can be omitted if the entire trailer up to and including
+ a preceding closing bracket fits in one line.
- Note: this usually looks weird, only use this for function definitions.
- Prefer RHS otherwise.
+ Yielded sets are cumulative (contain results of previous yields, too). First
+ set is empty.
"""
- head = Line(depth=line.depth)
- body = Line(depth=line.depth + 1, inside_brackets=True)
- tail = Line(depth=line.depth)
- tail_leaves: List[Leaf] = []
- body_leaves: List[Leaf] = []
- head_leaves: List[Leaf] = []
- current_leaves = head_leaves
- matching_bracket = 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 # type: ignore
- ):
- current_leaves = tail_leaves
- current_leaves.append(leaf)
- if current_leaves is head_leaves:
- if leaf.type in OPENING_BRACKETS:
- matching_bracket = leaf
- current_leaves = body_leaves
- # Since body is a new indent level, remove spurious leading whitespace.
- if body_leaves:
- normalize_prefix(body_leaves[0])
- # Build the new lines.
- for result, leaves in (
- (head, head_leaves), (body, body_leaves), (tail, tail_leaves)
- ):
- for leaf in leaves:
- result.append(leaf, preformatted=True)
- comment_after = line.comments.get(id(leaf))
- if comment_after:
- result.append(comment_after, preformatted=True)
- # Check if the split succeeded.
- tail_len = len(str(tail))
- 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 "
- f"{tail_len} characters is not worth it"
- )
+ omit: Set[LeafID] = set()
+ yield omit
- for result in (head, body, tail):
- if result:
- yield result
+ 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
-def right_hand_split(line: Line) -> Iterator[Line]:
- """Split line into many lines, starting with the last matching bracket pair."""
- head = Line(depth=line.depth)
- body = Line(depth=line.depth + 1, inside_brackets=True)
- tail = Line(depth=line.depth)
- tail_leaves: List[Leaf] = []
- body_leaves: List[Leaf] = []
- head_leaves: List[Leaf] = []
- current_leaves = tail_leaves
- opening_bracket = None
- for leaf in reversed(line.leaves):
- if current_leaves is body_leaves:
+ if opening_bracket:
if leaf is opening_bracket:
- current_leaves = head_leaves
- current_leaves.append(leaf)
- if current_leaves is tail_leaves:
- if leaf.type in CLOSING_BRACKETS:
- opening_bracket = leaf.opening_bracket # type: ignore
- current_leaves = body_leaves
- tail_leaves.reverse()
- body_leaves.reverse()
- head_leaves.reverse()
- # Since body is a new indent level, remove spurious leading whitespace.
- if body_leaves:
- normalize_prefix(body_leaves[0])
- # Build the new lines.
- for result, leaves in (
- (head, head_leaves), (body, body_leaves), (tail, tail_leaves)
- ):
- for leaf in leaves:
- result.append(leaf, preformatted=True)
- comment_after = line.comments.get(id(leaf))
- if comment_after:
- result.append(comment_after, preformatted=True)
- # Check if the split succeeded.
- tail_len = len(str(tail).strip('\n'))
- if not body:
- if tail_len == 0:
- raise CannotSplit("Splitting brackets produced the same line")
+ opening_bracket = None
+ elif leaf.type in CLOSING_BRACKETS:
+ inner_brackets.add(id(leaf))
+ elif leaf.type in CLOSING_BRACKETS:
+ if index > 0 and line.leaves[index - 1].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
- elif tail_len < 3:
- raise CannotSplit(
- f"Splitting brackets on an empty body to save "
- f"{tail_len} characters is not worth it"
- )
+ if closing_bracket:
+ omit.add(id(closing_bracket))
+ omit.update(inner_brackets)
+ inner_brackets.clear()
+ yield omit
- for result in (head, body, tail):
- if result:
- yield result
+ if leaf.value:
+ opening_bracket = leaf.opening_bracket
+ closing_bracket = leaf
-def delimiter_split(line: Line) -> Iterator[Line]:
- """Split according to delimiters of the highest priority.
+def get_future_imports(node: Node) -> Set[str]:
+ """Return a set of __future__ imports in the file."""
+ imports: Set[str] = set()
- This kind of split doesn't increase indentation.
- """
- try:
- last_leaf = line.leaves[-1]
- except IndexError:
- raise CannotSplit("Line empty")
+ 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
- delimiters = line.bracket_tracker.delimiters
- try:
- delimiter_priority = line.bracket_tracker.max_priority(exclude={id(last_leaf)})
- except ValueError:
- raise CannotSplit("No delimiters found")
+ 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
- current_line = Line(depth=line.depth, inside_brackets=line.inside_brackets)
- for leaf in line.leaves:
- current_line.append(leaf, preformatted=True)
- comment_after = line.comments.get(id(leaf))
- if comment_after:
- current_line.append(comment_after, preformatted=True)
- leaf_priority = delimiters.get(id(leaf))
- if leaf_priority == delimiter_priority:
- normalize_prefix(current_line.leaves[0])
- yield current_line
+ elif child.type == syms.import_as_names:
+ yield from get_imports_from_children(child.children)
- current_line = Line(depth=line.depth, inside_brackets=line.inside_brackets)
- if current_line:
- if (
- delimiter_priority == COMMA_PRIORITY and
- current_line.leaves[-1].type != token.COMMA
- ):
- current_line.append(Leaf(token.COMMA, ','))
- normalize_prefix(current_line.leaves[0])
- yield current_line
+ else:
+ raise AssertionError("Invalid syntax parsing imports")
+ for child in node.children:
+ if child.type != syms.simple_stmt:
+ break
-def is_import(leaf: Leaf) -> bool:
- """Returns 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)
- )
- )
+ 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
-def normalize_prefix(leaf: Leaf) -> None:
- """Leave existing extra newlines for imports. Remove everything else."""
- if is_import(leaf):
- spl = leaf.prefix.split('#', 1)
- nl_count = spl[0].count('\n')
- if len(spl) > 1:
- # Skip one newline since it was for a standalone comment.
- nl_count -= 1
- leaf.prefix = '\n' * nl_count
- return
+ imports |= set(get_imports_from_children(first_child.children[3:]))
+ else:
+ break
- leaf.prefix = ''
+ return imports
-PYTHON_EXTENSIONS = {'.py'}
-BLACKLISTED_DIRECTORIES = {
- 'build', 'buck-out', 'dist', '_build', '.git', '.hg', '.mypy_cache', '.tox', '.venv'
-}
+@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 gen_python_files_in_dir(
+ path: Path,
+ root: Path,
+ include: Pattern[str],
+ exclude: Pattern[str],
+ report: "Report",
+ gitignore: PathSpec,
+) -> Iterator[Path]:
+ """Generate all files under `path` whose paths are not excluded by the
+ `exclude` regex, but are included by the `include` regex.
+ Symbolic links pointing outside of the `root` directory are ignored.
-def gen_python_files_in_dir(path: Path) -> Iterator[Path]:
+ `report` is where output about exclusions goes.
+ """
+ assert root.is_absolute(), f"INTERNAL ERROR: `root` must be absolute but is {root}"
for child in path.iterdir():
- if child.is_dir():
- if child.name in BLACKLISTED_DIRECTORIES:
+ # First ignore files matching .gitignore
+ if gitignore.match_file(child.as_posix()):
+ report.path_ignored(child, "matches the .gitignore file content")
+ continue
+
+ # Then ignore with `exclude` option.
+ try:
+ normalized_path = "/" + child.resolve().relative_to(root).as_posix()
+ except OSError as e:
+ report.path_ignored(child, f"cannot be read because {e}")
+ continue
+
+ except ValueError:
+ if child.is_symlink():
+ report.path_ignored(
+ child, f"is a symbolic link that points outside {root}"
+ )
continue
- yield from gen_python_files_in_dir(child)
+ raise
+
+ if child.is_dir():
+ normalized_path += "/"
+
+ exclude_match = exclude.search(normalized_path)
+ if exclude_match and exclude_match.group(0):
+ report.path_ignored(child, "matches the --exclude regular expression")
+ continue
+
+ if child.is_dir():
+ yield from gen_python_files_in_dir(
+ child, root, include, exclude, report, gitignore
+ )
+
+ elif child.is_file():
+ include_match = include.search(normalized_path)
+ if include_match:
+ yield child
- elif child.suffix in PYTHON_EXTENSIONS:
- yield child
+
+@lru_cache()
+def find_project_root(srcs: Iterable[str]) -> Path:
+ """Return a directory containing .git, .hg, or pyproject.toml.
+
+ That directory can be one of the directories passed in `srcs` or their
+ common parent.
+
+ 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()
+
+ common_base = min(Path(src).resolve() for src in srcs)
+ if common_base.is_dir():
+ # Append a fake file so `parents` below returns `common_base_dir`, too.
+ common_base /= "fake-file"
+ for directory in 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
@dataclass
class Report:
- """Provides a reformatting counter."""
- change_count: int = attrib(default=0)
- same_count: int = attrib(default=0)
- failure_count: int = attrib(default=0)
+ """Provides a reformatting counter. Can be rendered with `str(report)`."""
- def done(self, src: Path, changed: bool) -> None:
+ 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:
- out(f'reformatted {src}')
+ 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:
- out(f'{src} already well formatted, good job.', bold=False)
+ 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}')
+ 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:
- """Which return code should the app use considering the current state."""
+ """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 returncodes reserved by the shell.
+ # 126 we have special return codes reserved by the shell.
if self.failure_count:
return 123
- elif self.change_count:
+ elif self.change_count and self.check:
return 1
return 0
def __str__(self) -> str:
- """A color report of the current state.
+ """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 ''
+ s = "s" if self.change_count > 1 else ""
report.append(
- click.style(f'{self.change_count} file{s} reformatted', bold=True)
+ 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} left unchanged')
+ 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 ''
+ s = "s" if self.failure_count > 1 else ""
report.append(
- click.style(
- f'{self.failure_count} file{s} failed to reformat', fg='red'
- )
+ click.style(f"{self.failure_count} file{s} {failed}", fg="red")
)
- return ', '.join(report) + '.'
+ return ", ".join(report) + "."
-def assert_equivalent(src: str, dst: str) -> None:
- """Raises AssertionError if `src` and `dst` aren't equivalent.
+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
- This is a temporary sanity check until Black becomes stable.
- """
+ return ast27.parse(src)
- import ast
- import traceback
- def _v(node: ast.AST, depth: int = 0) -> Iterator[str]:
- """Simple visitor generating strings to compare ASTs by content."""
- 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)
- for field in sorted(node._fields):
- try:
- value = getattr(node, field)
- except AttributeError:
- continue
+ 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
- yield f"{' ' * (depth+1)}{field}="
+ 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)
- if isinstance(value, list):
- for item in value:
- if isinstance(item, ast.AST):
- yield from _v(item, depth + 2)
+ elif isinstance(item, (ast.AST, ast3.AST, ast27.AST)):
+ yield from _stringify_ast(item, depth + 2)
- elif isinstance(value, ast.AST):
- yield from _v(value, 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
+ if (
+ isinstance(node, ast.Constant)
+ and field == "value"
+ and isinstance(value, str)
+ ):
+ normalized = re.sub(r"\n[ \t]+", "\n ", value)
else:
- yield f"{' ' * (depth+2)}{value!r}, # {value.__class__.__name__}"
+ normalized = value
+ yield f"{' ' * (depth+2)}{normalized!r}, # {value.__class__.__name__}"
- yield f"{' ' * depth}) # /{node.__class__.__name__}"
+ yield f"{' ' * depth}) # /{node.__class__.__name__}"
+
+def assert_equivalent(src: str, dst: str) -> None:
+ """Raise AssertionError if `src` and `dst` aren't equivalent."""
try:
- src_ast = ast.parse(src)
+ src_ast = parse_ast(src)
except Exception as exc:
- raise AssertionError(f"cannot parse source: {exc}") from None
+ raise AssertionError(
+ "cannot use --safe with this file; failed to parse source file. AST"
+ f" error message: {exc}"
+ )
try:
- dst_ast = ast.parse(dst)
+ dst_ast = parse_ast(dst)
except Exception as exc:
- log = dump_to_file(''.join(traceback.format_tb(exc.__traceback__)), dst)
+ log = dump_to_file("".join(traceback.format_tb(exc.__traceback__)), dst)
raise AssertionError(
- f"INTERNAL ERROR: Black produced invalid code: {exc}. "
- f"Please report a bug on https://github.com/ambv/black/issues. "
- f"This invalid output might be helpful: {log}",
+ f"INTERNAL ERROR: Black produced invalid code: {exc}. Please report a bug"
+ " on https://github.com/psf/black/issues. This invalid output might be"
+ f" helpful: {log}"
) from None
- src_ast_str = '\n'.join(_v(src_ast))
- dst_ast_str = '\n'.join(_v(dst_ast))
+ 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'))
+ log = dump_to_file(diff(src_ast_str, dst_ast_str, "src", "dst"))
raise AssertionError(
- f"INTERNAL ERROR: Black produced code that is not equivalent to "
- f"the source. "
- f"Please report a bug on https://github.com/ambv/black/issues. "
- f"This diff might be helpful: {log}",
+ "INTERNAL ERROR: Black produced code that is not equivalent to the"
+ " source. Please report a bug on https://github.com/psf/black/issues. "
+ f" This diff might be helpful: {log}"
) from None
-def assert_stable(src: str, dst: str, line_length: int) -> None:
- """Raises AssertionError if `dst` reformats differently the second time.
-
- This is a temporary sanity check until Black becomes stable.
- """
- newdst = format_str(dst, line_length=line_length)
+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(
- diff(src, dst, 'source', 'first pass'),
- diff(dst, newdst, 'first pass', 'second pass'),
+ diff(src, dst, "source", "first pass"),
+ diff(dst, newdst, "first pass", "second pass"),
)
raise AssertionError(
- f"INTERNAL ERROR: Black produced different code on the second pass "
- f"of the formatter. "
- f"Please report a bug on https://github.com/ambv/black/issues. "
- f"This diff might be helpful: {log}",
+ "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) -> str:
- """Dumps `output` to a temporary file. Returns path to the file."""
- import tempfile
-
+ """Dump `output` to a temporary file. Return path to the file."""
with tempfile.NamedTemporaryFile(
- mode='w', prefix='blk_', suffix='.log', delete=False
+ mode="w", prefix="blk_", suffix=".log", delete=False, encoding="utf8"
) as f:
for lines in output:
f.write(lines)
- f.write('\n')
+ if 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:
- """Returns a udiff string between strings `a` and `b`."""
+ """Return a unified diff string between strings `a` and `b`."""
import difflib
- a_lines = [line + '\n' for line in a.split('\n')]
- b_lines = [line + '\n' for line in b.split('\n')]
- return ''.join(
+ a_lines = [line + "\n" for line in a.splitlines()]
+ b_lines = [line + "\n" for line in b.splitlines()]
+ return "".join(
difflib.unified_diff(a_lines, b_lines, fromfile=a_name, tofile=b_name, n=5)
)
-if __name__ == '__main__':
+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) -> 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"
+
+ first = line.leaves[0]
+ second = line.leaves[1]
+ penultimate = line.leaves[-2]
+ last = line.leaves[-1]
+
+ # With a single delimiter, omit if the expression starts or ends with
+ # a bracket.
+ if first.type in OPENING_BRACKETS and second.type not in CLOSING_BRACKETS:
+ remainder = False
+ length = 4 * line.depth
+ 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
+
+ # 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.
+
+ 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
+
+ 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 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:
+ src = src.resolve()
+ if cache.get(src) != get_cache_info(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, **{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
+
+
+def patched_main() -> None:
+ freeze_support()
+ patch_click()
main()
+
+
+def fix_docstring(docstring: str, prefix: str) -> str:
+ # https://www.python.org/dev/peps/pep-0257/#handling-docstring-indentation
+ if not docstring:
+ return ""
+ # Convert tabs to spaces (following the normal Python rules)
+ # and split into a list of lines:
+ lines = docstring.expandtabs().splitlines()
+ # 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 a single string:
+ return "\n".join(trimmed)
+
+
+if __name__ == "__main__":
+ patched_main()
projects / etc / vim.git / blobdiff