+import ast
import asyncio
-from concurrent.futures import Executor, ProcessPoolExecutor
+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 os
from pathlib import Path
import pickle
-import re
+import regex as re
import signal
import sys
import tempfile
Pattern,
Sequence,
Set,
+ Sized,
Tuple,
+ Type,
TypeVar,
Union,
cast,
+ TYPE_CHECKING,
)
+from typing_extensions import Final
+from mypy_extensions import mypyc_attr
from appdirs import user_cache_dir
-from attr import dataclass, evolve, Factory
+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.pgen2.grammar import Grammar
from blib2to3.pgen2.parse import ParseError
+from _black_version import version as __version__
+
+if TYPE_CHECKING:
+ import colorama # noqa: F401
-__version__ = "19.3b0"
DEFAULT_LINE_LENGTH = 88
-DEFAULT_EXCLUDES = (
- r"/(\.eggs|\.git|\.hg|\.mypy_cache|\.nox|\.tox|\.venv|_build|buck-out|build|dist)/"
-)
+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
FileContent = str
NewLine = str
Depth = int
NodeType = int
+ParserState = int
LeafID = int
+StringID = int
Priority = int
Index = int
LN = Union[Leaf, Node]
-SplitFunc = Callable[["Line", Collection["Feature"]], Iterator["Line"]]
+Transformer = Callable[["Line", Collection["Feature"]], Iterator["Line"]]
Timestamp = float
FileSize = int
CacheInfo = Tuple[Timestamp, FileSize]
"""Raised when reformatted code is the same as source."""
-class CannotSplit(Exception):
+class CannotTransform(Exception):
+ """Base class for errors raised by Transformers."""
+
+
+class CannotSplit(CannotTransform):
"""A readable split that fits the allotted line length is impossible."""
"""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) -> "WriteBack":
+ 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
# 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]] = {
Feature.TRAILING_COMMA_IN_CALL,
Feature.TRAILING_COMMA_IN_DEF,
Feature.ASYNC_KEYWORDS,
+ Feature.ASSIGNMENT_EXPRESSIONS,
+ Feature.POS_ONLY_ARGUMENTS,
},
}
@dataclass
-class FileMode:
- target_versions: Set[TargetVersion] = Factory(set)
+class Mode:
+ target_versions: Set[TargetVersion] = field(default_factory=set)
line_length: int = DEFAULT_LINE_LENGTH
string_normalization: bool = True
is_pyi: bool = False
return ".".join(parts)
+# Legacy name, left for integrations.
+FileMode = Mode
+
+
def supports_feature(target_versions: Set[TargetVersion], feature: Feature) -> bool:
return all(feature in VERSION_TO_FEATURES[version] for version in target_versions)
+def find_pyproject_toml(path_search_start: 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
+
+
+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: Union[str, int, bool, None]
+ 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.
"""
- assert not isinstance(value, (int, bool)), "Invalid parameter type passed"
if not value:
- root = find_project_root(ctx.params.get("src", ()))
- path = root / "pyproject.toml"
- if path.is_file():
- value = str(path)
- else:
+ value = find_pyproject_toml(ctx.params.get("src", ()))
+ if value is None:
return None
try:
- pyproject_toml = toml.load(value)
- config = pyproject_toml.get("tool", {}).get("black", {})
+ 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
- if ctx.default_map is None:
- ctx.default_map = {}
- ctx.default_map.update( # type: ignore # bad types in .pyi
- {k.replace("--", "").replace("-", "_"): v for k, v in config.items()}
- )
+ 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(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(
"-t",
"--target-version",
type=click.Choice([v.name.lower() for v in TargetVersion]),
- callback=lambda c, p, v: [TargetVersion[val.upper()] for val in v],
+ 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]"
+ "Python versions that should be supported by Black's output. [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)."
+ "Format all input files like typing stubs regardless of file extension (useful"
+ " when piping source on standard input)."
),
)
@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."
+ "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(
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,
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."
+ "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,
)
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."
+ "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(
+ "--force-exclude",
+ type=str,
+ help=(
+ "Like --exclude, but files and directories matching this regex will be "
+ "excluded even when they are passed explicitly as arguments"
+ ),
+)
@click.option(
"-q",
"--quiet",
is_flag=True,
help=(
- "Don't emit non-error messages to stderr. Errors are still emitted; "
- "silence those with 2>/dev/null."
+ "Don't emit non-error messages to stderr. Errors are still emitted; silence"
+ " those with 2>/dev/null."
),
)
@click.option(
"--verbose",
is_flag=True,
help=(
- "Also emit messages to stderr about files that were not changed or were "
- "ignored due to --exclude=."
+ "Also emit messages to stderr about files that were not changed or were ignored"
+ " due to --exclude=."
),
)
@click.version_option(version=__version__)
@click.option(
"--config",
type=click.Path(
- exists=False, file_okay=True, dir_okay=False, readable=True, allow_dash=False
+ exists=True,
+ file_okay=True,
+ dir_okay=False,
+ readable=True,
+ allow_dash=False,
+ path_type=str,
),
is_eager=True,
callback=read_pyproject_toml,
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],
+ force_exclude: Optional[str],
+ src: Tuple[str, ...],
config: Optional[str],
) -> None:
"""The uncompromising code formatter."""
- write_back = WriteBack.from_configuration(check=check, diff=diff)
+ write_back = WriteBack.from_configuration(check=check, diff=diff, color=color)
if target_version:
- if py36:
- err(f"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
+ versions = set(target_version)
else:
# We'll autodetect later.
versions = set()
- mode = FileMode(
+ mode = Mode(
target_versions=versions,
line_length=line_length,
is_pyi=pyi,
if code is not None:
print(format_str(code, mode=mode))
ctx.exit(0)
+ report = Report(check=check, diff=diff, quiet=quiet, verbose=verbose)
+ sources = get_sources(
+ ctx=ctx,
+ src=src,
+ quiet=quiet,
+ verbose=verbose,
+ include=include,
+ exclude=exclude,
+ force_exclude=force_exclude,
+ report=report,
+ )
+
+ path_empty(
+ sources,
+ "No Python files are present to be formatted. Nothing to do 😴",
+ quiet,
+ verbose,
+ ctx,
+ )
+
+ if len(sources) == 1:
+ reformat_one(
+ src=sources.pop(),
+ fast=fast,
+ write_back=write_back,
+ mode=mode,
+ report=report,
+ )
+ else:
+ 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 get_sources(
+ *,
+ ctx: click.Context,
+ src: Tuple[str, ...],
+ quiet: bool,
+ verbose: bool,
+ include: str,
+ exclude: str,
+ force_exclude: Optional[str],
+ report: "Report",
+) -> Set[Path]:
+ """Compute the set of files to be formatted."""
try:
include_regex = re_compile_maybe_verbose(include)
except re.error:
except re.error:
err(f"Invalid regular expression for exclude given: {exclude!r}")
ctx.exit(2)
- report = Report(check=check, quiet=quiet, verbose=verbose)
+ try:
+ force_exclude_regex = (
+ re_compile_maybe_verbose(force_exclude) if force_exclude else None
+ )
+ except re.error:
+ err(f"Invalid regular expression for force_exclude given: {force_exclude!r}")
+ ctx.exit(2)
+
root = find_project_root(src)
sources: Set[Path] = set()
+ path_empty(src, "No Path provided. Nothing to do 😴", quiet, verbose, ctx)
+ exclude_regexes = [exclude_regex]
+ if force_exclude_regex is not None:
+ exclude_regexes.append(force_exclude_regex)
+
for s in src:
p = Path(s)
if p.is_dir():
sources.update(
- gen_python_files_in_dir(p, root, include_regex, exclude_regex, report)
+ gen_python_files(
+ p.iterdir(),
+ root,
+ include_regex,
+ exclude_regexes,
+ report,
+ get_gitignore(root),
+ )
)
- elif p.is_file() or s == "-":
- # if a file was explicitly given, we don't care about its extension
+ elif s == "-":
sources.add(p)
+ elif p.is_file():
+ sources.update(
+ gen_python_files(
+ [p], root, None, exclude_regexes, report, get_gitignore(root)
+ )
+ )
else:
err(f"invalid path: {s}")
- if len(sources) == 0:
- if verbose or not quiet:
- out("No paths given. Nothing to do 😴")
- ctx.exit(0)
+ return sources
- if len(sources) == 1:
- reformat_one(
- src=sources.pop(),
- fast=fast,
- write_back=write_back,
- mode=mode,
- report=report,
- )
- else:
- 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: Sized, msg: str, quiet: bool, verbose: bool, ctx: click.Context
+) -> None:
+ """
+ Exit if there is no `src` provided for formatting
+ """
+ if len(src) == 0:
+ if verbose or not quiet:
+ out(msg)
+ ctx.exit(0)
def reformat_one(
- src: Path, fast: bool, write_back: WriteBack, mode: FileMode, report: "Report"
+ src: Path, fast: bool, write_back: WriteBack, mode: Mode, report: "Report"
) -> None:
"""Reformat a single file under `src` without spawning child processes.
def reformat_many(
- sources: Set[Path],
- fast: bool,
- write_back: WriteBack,
- mode: FileMode,
- report: "Report",
+ 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)
- executor = ProcessPoolExecutor(max_workers=worker_count)
+ 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(
)
finally:
shutdown(loop)
+ if executor is not None:
+ executor.shutdown()
async def schedule_formatting(
sources: Set[Path],
fast: bool,
write_back: WriteBack,
- mode: FileMode,
+ mode: Mode,
report: "Report",
loop: asyncio.AbstractEventLoop,
executor: Executor,
): src
for src in sorted(sources)
}
- pending: Iterable[asyncio.Future] = tasks.keys()
+ pending: Iterable["asyncio.Future[bool]"] = tasks.keys()
try:
loop.add_signal_handler(signal.SIGINT, cancel, pending)
loop.add_signal_handler(signal.SIGTERM, cancel, pending)
def format_file_in_place(
src: Path,
fast: bool,
- mode: FileMode,
+ mode: Mode,
write_back: WriteBack = WriteBack.NO,
lock: Any = None, # multiprocessing.Manager().Lock() is some crazy proxy
) -> bool:
`mode` and `fast` options are passed to :func:`format_file_contents`.
"""
if src.suffix == ".pyi":
- mode = evolve(mode, is_pyi=True)
+ mode = replace(mode, is_pyi=True)
then = datetime.utcfromtimestamp(src.stat().st_mtime)
with open(src, "rb") as buf:
except NothingChanged:
return False
- if write_back == write_back.YES:
+ if write_back == WriteBack.YES:
with open(src, "w", encoding=encoding, newline=newline) as f:
f.write(dst_contents)
- elif write_back == write_back.DIFF:
+ 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 lock:
- lock.acquire()
- try:
+
+ 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()
- finally:
- if lock:
- lock.release()
+
return True
+def color_diff(contents: str) -> str:
+ """Inject the ANSI color codes to the diff."""
+ lines = contents.split("\n")
+ for i, line in enumerate(lines):
+ if line.startswith("+++") or line.startswith("---"):
+ line = "\033[1;37m" + line + "\033[0m" # bold white, reset
+ 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: FileMode
+ fast: bool, *, write_back: WriteBack = WriteBack.NO, mode: Mode
) -> bool:
"""Format file on stdin. Return True if changed.
)
if write_back == WriteBack.YES:
f.write(dst)
- elif write_back == WriteBack.DIFF:
+ 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"
- f.write(diff(src, dst, src_name, dst_name))
+ 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: FileMode
-) -> FileContent:
+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
return dst_contents
-def format_str(src_contents: str, *, mode: FileMode) -> FileContent:
+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.
+ 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
+
"""
src_node = lib2to3_parse(src_contents.lstrip(), mode.target_versions)
dst_contents = []
if supports_feature(versions, feature)
}
for current_line in lines.visit(src_node):
- for _ in range(after):
- dst_contents.append(str(empty_line))
+ dst_contents.append(str(empty_line) * after)
before, after = elt.maybe_empty_lines(current_line)
- for _ in range(before):
- dst_contents.append(str(empty_line))
- for line in split_line(
- current_line, line_length=mode.line_length, features=split_line_features
+ 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)
# Python 2.7
pygram.python_grammar,
]
- elif all(version.is_python2() for version in target_versions):
+
+ 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
# Python 2.7
pygram.python_grammar,
]
- else:
- # 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 # noqa: B950
- )
- 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
+
+ # Python 3-compatible code, so only try Python 3 grammar.
+ grammars = []
+ # If we have to parse both, try to parse async as a keyword first
+ if not supports_feature(target_versions, Feature.ASYNC_IDENTIFIERS):
+ # Python 3.7+
+ grammars.append(
+ pygram.python_grammar_no_print_statement_no_exec_statement_async_keywords
+ )
+ if not supports_feature(target_versions, Feature.ASYNC_KEYWORDS):
+ # Python 3.0-3.6
+ grammars.append(pygram.python_grammar_no_print_statement_no_exec_statement)
+ # At least one of the above branches must have been taken, because every Python
+ # version has exactly one of the two 'ASYNC_*' flags
+ return grammars
def lib2to3_parse(src_txt: str, target_versions: Iterable[TargetVersion] = ()) -> Node:
return code
-T = TypeVar("T")
-
-
class Visitor(Generic[T]):
"""Basic lib2to3 visitor that yields things of type `T` on `visit()`."""
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`."""
list(v.visit(code))
-WHITESPACE = {token.DEDENT, token.INDENT, token.NEWLINE}
-STATEMENT = {
+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
+STANDALONE_COMMENT: Final = 153
token.tok_name[STANDALONE_COMMENT] = "STANDALONE_COMMENT"
-LOGIC_OPERATORS = {"and", "or"}
-COMPARATORS = {
+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.TILDE,
token.DOUBLESTAR,
}
-STARS = {token.STAR, token.DOUBLESTAR}
-VARARGS_PARENTS = {
+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 = {
+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 = {
+TEST_DESCENDANTS: Final = {
syms.test,
syms.lambdef,
syms.or_test,
syms.term,
syms.power,
}
-ASSIGNMENTS = {
+ASSIGNMENTS: Final = {
"=",
"+=",
"-=",
"**=",
"//=",
}
-COMPREHENSION_PRIORITY = 20
-COMMA_PRIORITY = 18
-TERNARY_PRIORITY = 16
-LOGIC_PRIORITY = 14
-STRING_PRIORITY = 12
-COMPARATOR_PRIORITY = 10
-MATH_PRIORITIES = {
+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.TILDE: 3,
token.DOUBLESTAR: 2,
}
-DOT_PRIORITY = 1
+DOT_PRIORITY: Final = 1
@dataclass
"""Keeps track of brackets on a line."""
depth: int = 0
- bracket_match: Dict[Tuple[Depth, NodeType], Leaf] = Factory(dict)
- delimiters: Dict[LeafID, Priority] = Factory(dict)
+ 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] = Factory(list)
- _lambda_argument_depths: List[int] = Factory(list)
+ _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.
"""Holds leaves and comments. Can be printed with `str(line)`."""
depth: int = 0
- leaves: List[Leaf] = Factory(list)
- comments: Dict[LeafID, List[Leaf]] = Factory(dict) # keys ordered like `leaves`
- bracket_tracker: BracketTracker = Factory(BracketTracker)
+ 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
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:
"""Is this a function definition? (Also returns True for async defs.)"""
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:
- if leaf.bracket_depth <= depth_limit:
- return True
+ if leaf.type == STANDALONE_COMMENT and leaf.bracket_depth <= depth_limit:
+ return True
+
return False
- def contains_inner_type_comments(self) -> bool:
+ def contains_uncollapsable_type_comments(self) -> bool:
ignored_ids = set()
try:
last_leaf = self.leaves[-1]
except IndexError:
return False
+ # A type comment is uncollapsable if it is attached to a leaf
+ # that isn't at the end of the line (since that could cause it
+ # to get associated to a different argument) or if there are
+ # comments before it (since that could cause it to get hidden
+ # behind a comment.
+ comment_seen = False
for leaf_id, comments in self.comments.items():
- if leaf_id in ignored_ids:
- continue
-
for comment in comments:
if is_type_comment(comment):
- return True
+ if comment_seen or (
+ not is_type_comment(comment, " ignore")
+ and leaf_id not in ignored_ids
+ ):
+ return True
+
+ comment_seen = True
return False
- def contains_multiline_strings(self) -> bool:
- for leaf in self.leaves:
- if is_multiline_string(leaf):
- return True
+ def contains_unsplittable_type_ignore(self) -> bool:
+ if not self.leaves:
+ return False
+
+ # If a 'type: ignore' is attached to the end of a line, we
+ # can't split the line, because we can't know which of the
+ # subexpressions the ignore was meant to apply to.
+ #
+ # We only want this to apply to actual physical lines from the
+ # original source, though: we don't want the presence of a
+ # 'type: ignore' at the end of a multiline expression to
+ # justify pushing it all onto one line. Thus we
+ # (unfortunately) need to check the actual source lines and
+ # only report an unsplittable 'type: ignore' if this line was
+ # one line in the original code.
+
+ # Grab the first and last line numbers, skipping generated leaves
+ first_line = next((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 contains_multiline_strings(self) -> bool:
+ return any(is_multiline_string(leaf) for leaf in self.leaves)
+
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
+
+ # We remove trailing commas only in the case of importing a
+ # single name from a module.
if not (
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
- if closing.type == token.RBRACE:
- self.remove_trailing_comma()
- return True
-
- if closing.type == token.RSQB:
- comma = self.leaves[-1]
- if comma.parent and comma.parent.type == syms.listmaker:
- self.remove_trailing_comma()
- return True
-
- # For parens let's check if it's safe to remove the comma.
- # Imports are always safe.
- if self.is_import:
- self.remove_trailing_comma()
- return True
-
- # Otherwise, 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
- commas = 0
- opening = closing.opening_bracket
- for _opening_index, leaf in enumerate(self.leaves):
- if leaf is opening:
- break
-
- else:
- return False
-
- for leaf in self.leaves[_opening_index + 1 :]:
- if leaf is closing:
- break
-
- bracket_depth = leaf.bracket_depth
- if bracket_depth == depth and leaf.type == token.COMMA:
- commas += 1
- if leaf.parent and leaf.parent.type in {
- syms.arglist,
- syms.typedargslist,
- }:
- commas += 1
- break
-
- if commas > 1:
- self.remove_trailing_comma()
- return True
-
- return False
+ self.remove_trailing_comma()
+ return True
def append_comment(self, comment: Leaf) -> bool:
"""Add an inline or standalone comment to the line."""
comment.type = STANDALONE_COMMENT
comment.prefix = ""
return False
+
last_leaf = self.leaves[-2]
self.comments.setdefault(id(last_leaf), []).append(comment)
return True
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:
res += str(leaf)
for comment in itertools.chain.from_iterable(self.comments.values()):
res += str(comment)
+
return res + "\n"
def __bool__(self) -> bool:
is_pyi: bool = False
previous_line: Optional[Line] = None
previous_after: int = 0
- previous_defs: List[int] = Factory(list)
+ previous_defs: List[int] = field(default_factory=list)
def maybe_empty_lines(self, current_line: Line) -> Tuple[int, int]:
"""Return the number of extra empty lines before and after the `current_line`.
lines (two on module-level).
"""
before, after = self._maybe_empty_lines(current_line)
- before -= self.previous_after
+ 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
is_pyi: bool = False
normalize_strings: bool = True
- current_line: Line = Factory(Line)
+ current_line: Line = field(default_factory=Line)
remove_u_prefix: bool = False
def line(self, indent: int = 0) -> Iterator[Line]:
self.current_line.append(node)
yield from super().visit_default(node)
- def visit_atom(self, node: Node) -> Iterator[Line]:
- # Always make parentheses invisible around a single node, because it should
- # not be needed (except in the case of yield, where removing the parentheses
- # produces a SyntaxError).
- if (
- len(node.children) == 3
- and isinstance(node.children[0], Leaf)
- and node.children[0].type == token.LPAR
- and isinstance(node.children[2], Leaf)
- and node.children[2].type == token.RPAR
- and isinstance(node.children[1], Leaf)
- and not (
- node.children[1].type == token.NAME
- and node.children[1].value == "yield"
- )
- ):
- node.children[0].value = ""
- node.children[2].value = ""
- yield from super().visit_default(node)
-
- def visit_factor(self, node: Node) -> Iterator[Line]:
- """Force parentheses between a unary op and a binary power:
-
- -2 ** 8 -> -(2 ** 8)
- """
- child = node.children[1]
- if child.type == syms.power and len(child.children) == 3:
- lpar = Leaf(token.LPAR, "(")
- rpar = Leaf(token.RPAR, ")")
- index = child.remove() or 0
- node.insert_child(index, Node(syms.atom, [lpar, child, rpar]))
- yield from self.visit_default(node)
-
- def visit_INDENT(self, node: Node) -> Iterator[Line]:
+ def visit_INDENT(self, node: Leaf) -> Iterator[Line]:
"""Increase indentation level, maybe yield a line."""
# In blib2to3 INDENT never holds comments.
yield from self.line(+1)
yield from self.visit_default(node)
- def visit_DEDENT(self, node: Node) -> Iterator[Line]:
+ 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).
yield from self.line()
yield from self.visit_default(leaf)
- def __attrs_post_init__(self) -> None:
+ 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
Ø: Set[str] = set()
# that, too.
return prevp.prefix
- elif prevp.type in STARS:
+ elif prevp.type in VARARGS_SPECIALS:
if is_vararg(prevp, within=VARARGS_PARENTS | UNPACKING_PARENTS):
return NO
if not prevp or prevp.type == token.LPAR:
return NO
- elif prev.type in {token.EQUAL} | STARS:
+ elif prev.type in {token.EQUAL} | VARARGS_SPECIALS:
return NO
elif p.type == syms.decorator:
return None
+def prev_siblings_are(node: Optional[LN], tokens: List[Optional[NodeType]]) -> bool:
+ """Return if the `node` and its previous siblings match types against the provided
+ list of tokens; the provided `node`has its type matched against the last element in
+ the list. `None` can be used as the first element to declare that the start of the
+ list is anchored at the start of its parent's children."""
+ if not tokens:
+ return True
+ if tokens[-1] is None:
+ return node is None
+ if not node:
+ return False
+ if node.type != tokens[-1]:
+ return False
+ return prev_siblings_are(node.prev_sibling, tokens[:-1])
+
+
def child_towards(ancestor: Node, descendant: LN) -> Optional[LN]:
"""Return the child of `ancestor` that contains `descendant`."""
node: Optional[LN] = descendant
return "#" + content
-def split_line(
+def transform_line(
line: Line,
line_length: int,
- inner: bool = False,
+ normalize_strings: bool,
features: Collection[Feature] = (),
) -> Iterator[Line]:
- """Split a `line` into potentially many lines.
+ """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.
"""
yield line
return
- line_str = str(line).strip("\n")
+ 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_inner_type_comments()
+ not line.contains_uncollapsable_type_comments()
and not line.should_explode
- and is_line_short_enough(line, line_length=line_length, line_str=line_str)
+ 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)
):
- yield line
- return
-
- split_funcs: List[SplitFunc]
- if line.is_def:
- split_funcs = [left_hand_split]
+ # 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:
def rhs(line: Line, features: Collection[Feature]) -> Iterator[Line]:
# 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.
- yield from right_hand_split(line, line_length, features=features)
+ # 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:
- split_funcs = [delimiter_split, standalone_comment_split, rhs]
+ transformers = [
+ string_merge,
+ string_paren_strip,
+ delimiter_split,
+ standalone_comment_split,
+ string_split,
+ string_paren_wrap,
+ rhs,
+ ]
else:
- split_funcs = [rhs]
- for split_func in split_funcs:
+ 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, features):
+ for l in transform(line, features):
if str(l).strip("\n") == line_str:
- raise CannotSplit("Split function returned an unchanged result")
+ raise CannotTransform(
+ "Line transformer returned an unchanged result"
+ )
result.extend(
- split_line(
- l, line_length=line_length, inner=True, features=features
+ transform_line(
+ l,
+ line_length=line_length,
+ normalize_strings=normalize_strings,
+ features=features,
)
)
- except CannotSplit:
+ except CannotTransform:
continue
-
else:
yield from result
break
yield line
-def left_hand_split(line: Line, features: Collection[Feature] = ()) -> Iterator[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.
body_leaves: List[Leaf] = []
head_leaves: List[Leaf] = []
current_leaves = head_leaves
- matching_bracket = None
+ matching_bracket: Optional[Leaf] = None
for leaf in line.leaves:
if (
current_leaves is body_leaves
body_leaves: List[Leaf] = []
head_leaves: List[Leaf] = []
current_leaves = tail_leaves
- opening_bracket = None
- closing_bracket = None
+ 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:
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."
+ "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)
elif tail_len < 3:
raise CannotSplit(
- f"Splitting brackets on an empty body to save "
- f"{tail_len} characters is not worth it"
+ f"Splitting brackets on an empty body to save {tail_len} characters is"
+ " not worth it"
)
# 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.
- no_commas = original.is_def and not any(
- l.type == token.COMMA for l in leaves
+ # 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
- elif leaves[i].type == token.COMMA:
- break
- else:
+
+ if leaves[i].type != token.COMMA:
leaves.insert(i + 1, Leaf(token.COMMA, ","))
- break
+ break
+
# Populate the line
for leaf in leaves:
result.append(leaf, preformatted=True)
return result
-def dont_increase_indentation(split_func: SplitFunc) -> SplitFunc:
+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.
)
-def is_type_comment(leaf: Leaf) -> bool:
+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, t == STANDALONE_COMMENT} and v.startswith("# type:")
+ return t in {token.COMMENT, STANDALONE_COMMENT} and v.startswith("# type:" + suffix)
def normalize_prefix(leaf: Leaf, *, inside_brackets: bool) -> None:
Note: Mutates its argument.
"""
- match = re.match(r"^([furbFURB]*)(.*)$", leaf.value, re.DOTALL)
+ 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.lower()
+ 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)}"
Note: Mutates its argument.
"""
- value = leaf.value.lstrip("furbFURB")
+ value = leaf.value.lstrip(STRING_PREFIX_CHARS)
if value[:3] == '"""':
return
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] + '\\"'
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
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):
- lpar = Leaf(token.LPAR, "")
- rpar = Leaf(token.RPAR, "")
- index = child.remove() or 0
- node.insert_child(index, Node(syms.atom, [lpar, child, rpar]))
+ wrap_in_parentheses(node, child, visible=False)
elif is_one_tuple(child):
- # wrap child in visible parentheses
- lpar = Leaf(token.LPAR, "(")
- rpar = Leaf(token.RPAR, ")")
- child.remove()
- node.insert_child(index, Node(syms.atom, [lpar, child, rpar]))
+ wrap_in_parentheses(node, child, visible=True)
elif node.type == syms.import_from:
# "import from" nodes store parentheses directly as part of
# the statement
break
elif not (isinstance(child, Leaf) and is_multiline_string(child)):
- # wrap child in invisible parentheses
- lpar = Leaf(token.LPAR, "")
- rpar = Leaf(token.RPAR, "")
- index = child.remove() or 0
- prefix = child.prefix
- child.prefix = ""
- new_child = Node(syms.atom, [lpar, child, rpar])
- new_child.prefix = prefix
- node.insert_child(index, new_child)
+ wrap_in_parentheses(node, child, visible=False)
check_lpar = isinstance(child, Leaf) and child.value in parens_after
# 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 = None
+ first_idx: Optional[int] = None
for ignored in ignored_nodes:
index = ignored.remove()
if first_idx is None:
"""
container: Optional[LN] = container_of(leaf)
while container is not None and container.type != token.ENDMARKER:
- for comment in list_comments(container.prefix, is_endmarker=False):
- if comment.value in FMT_ON:
- return
+ 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
+
- yield container
+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
- container = container.next_sibling
+ 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.
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
- if len(node.children) > 1:
- maybe_make_parens_invisible_in_atom(node.children[1], parent=parent)
+ 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 (
)
+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:
- if len(node.children) != 3:
- return False
-
- lpar, gexp, rpar = node.children
- if not (
- lpar.type == token.LPAR
- and gexp.type == syms.testlist_gexp
- and rpar.type == token.RPAR
- ):
+ 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
)
+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:
extended iterable unpacking (PEP 3132) and additional unpacking
generalizations (PEP 448).
"""
- if leaf.type not in STARS or not leaf.parent:
+ if leaf.type not in VARARGS_SPECIALS or not leaf.parent:
return False
p = leaf.parent
def is_multiline_string(leaf: Leaf) -> bool:
"""Return True if `leaf` is a multiline string that actually spans many lines."""
- value = leaf.value.lstrip("furbFURB")
- return value[:3] in {'"""', "'''"} and "\n" in value
+ return has_triple_quotes(leaf.value) and "\n" in leaf.value
def is_stub_suite(node: Node) -> bool:
Currently looking for:
- f-strings;
- - underscores in numeric literals; and
- - trailing commas after * or ** in function signatures and calls.
+ - 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 "_" 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
yield omit
length = 4 * line.depth
- opening_bracket = None
- closing_bracket = None
+ 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 isinstance(child, Leaf):
if child.type == token.NAME:
yield child.value
+
elif child.type == syms.import_as_name:
orig_name = child.children[0]
assert isinstance(orig_name, Leaf), "Invalid syntax parsing imports"
assert orig_name.type == token.NAME, "Invalid syntax parsing imports"
yield orig_name.value
+
elif child.type == syms.import_as_names:
yield from get_imports_from_children(child.children)
+
else:
raise AssertionError("Invalid syntax parsing imports")
for child in node.children:
if child.type != syms.simple_stmt:
break
+
first_child = child.children[0]
if isinstance(first_child, Leaf):
# Continue looking if we see a docstring; otherwise stop.
and child.children[1].type == token.NEWLINE
):
continue
- else:
- break
+
+ break
+
elif first_child.type == syms.import_from:
module_name = first_child.children[1]
if not isinstance(module_name, Leaf) or module_name.value != "__future__":
break
+
imports |= set(get_imports_from_children(first_child.children[3:]))
else:
break
+
return imports
-def gen_python_files_in_dir(
- path: Path,
+@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(
+ paths: Iterable[Path],
root: Path,
- include: Pattern[str],
- exclude: Pattern[str],
+ include: Optional[Pattern[str]],
+ exclude_regexes: Iterable[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.
`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():
+ for child in paths:
+ # Then ignore with `exclude` option.
try:
- normalized_path = "/" + child.resolve().relative_to(root).as_posix()
+ 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(
raise
+ # First ignore files matching .gitignore
+ if gitignore.match_file(normalized_path):
+ report.path_ignored(child, "matches the .gitignore file content")
+ continue
+
+ normalized_path = "/" + normalized_path
if child.is_dir():
normalized_path += "/"
- exclude_match = exclude.search(normalized_path)
- if exclude_match and exclude_match.group(0):
- report.path_ignored(child, f"matches the --exclude regular expression")
+
+ is_excluded = False
+ for exclude in exclude_regexes:
+ exclude_match = exclude.search(normalized_path) if exclude else None
+ if exclude_match and exclude_match.group(0):
+ report.path_ignored(child, "matches the --exclude regular expression")
+ is_excluded = True
+ break
+ if is_excluded:
continue
if child.is_dir():
- yield from gen_python_files_in_dir(child, root, include, exclude, report)
+ yield from gen_python_files(
+ child.iterdir(), root, include, exclude_regexes, report, gitignore
+ )
elif child.is_file():
- include_match = include.search(normalized_path)
+ include_match = include.search(normalized_path) if include else True
if include_match:
yield child
# 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").is_dir():
+ if (directory / ".git").exists():
return directory
if (directory / ".hg").is_dir():
"""Provides a reformatting counter. Can be rendered with `str(report)`."""
check: bool = False
+ diff: bool = False
quiet: bool = False
verbose: bool = False
change_count: int = 0
def done(self, src: Path, changed: Changed) -> None:
"""Increment the counter for successful reformatting. Write out a message."""
if changed is Changed.YES:
- reformatted = "would reformat" if self.check else "reformatted"
+ 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
Use `click.unstyle` to remove colors.
"""
- if self.check:
+ if self.check or self.diff:
reformatted = "would be reformatted"
unchanged = "would be left unchanged"
failed = "would fail to reformat"
return ", ".join(report) + "."
-def parse_ast(src: str) -> Union[ast3.AST, ast27.AST]:
- for feature_version in (7, 6):
- try:
- return ast3.parse(src, feature_version=feature_version)
- except SyntaxError:
- continue
+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
return ast27.parse(src)
-def assert_equivalent(src: str, dst: str) -> None:
- """Raise AssertionError if `src` and `dst` aren't equivalent."""
+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)
- def _v(node: Union[ast3.AST, ast27.AST], depth: int = 0) -> Iterator[str]:
- """Simple visitor generating strings to compare ASTs by content."""
- yield f"{' ' * depth}{node.__class__.__name__}("
+ if isinstance(node, (ast.Num, ast3.Num, ast27.Num)):
+ return ast.Constant(value=node.n)
- for field in sorted(node._fields):
- # TypeIgnore has only one field 'lineno' which breaks this comparison
- if isinstance(node, (ast3.TypeIgnore, ast27.TypeIgnore)):
- break
+ if isinstance(node, (ast.NameConstant, ast3.NameConstant)):
+ return ast.Constant(value=node.value)
- # Ignore str kind which is case sensitive / and ignores unicode_literals
- if isinstance(node, (ast3.Str, ast27.Str, ast3.Bytes)) and field == "kind":
- continue
+ return node
- try:
- value = getattr(node, field)
- except AttributeError:
- continue
- yield f"{' ' * (depth+1)}{field}="
+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."""
- 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, (ast3.Delete, ast27.Delete))
- and isinstance(item, (ast3.Tuple, ast27.Tuple))
- ):
- for item in item.elts:
- yield from _v(item, depth + 2)
- elif isinstance(item, (ast3.AST, ast27.AST)):
- yield from _v(item, depth + 2)
+ node = _fixup_ast_constants(node)
+
+ yield f"{' ' * depth}{node.__class__.__name__}("
+
+ for field in sorted(node._fields): # noqa: F402
+ # TypeIgnore has only one field 'lineno' which breaks this comparison
+ type_ignore_classes = (ast3.TypeIgnore, ast27.TypeIgnore)
+ if sys.version_info >= (3, 8):
+ type_ignore_classes += (ast.TypeIgnore,)
+ if isinstance(node, type_ignore_classes):
+ break
+
+ try:
+ value = getattr(node, field)
+ except AttributeError:
+ continue
+
+ yield f"{' ' * (depth+1)}{field}="
- elif isinstance(value, (ast3.AST, ast27.AST)):
- yield from _v(value, depth + 2)
+ if isinstance(value, list):
+ for item in value:
+ # Ignore nested tuples within del statements, because we may insert
+ # parentheses and they change the AST.
+ if (
+ field == "targets"
+ and isinstance(node, (ast.Delete, ast3.Delete, ast27.Delete))
+ and isinstance(item, (ast.Tuple, ast3.Tuple, ast27.Tuple))
+ ):
+ for item in item.elts:
+ yield from _stringify_ast(item, depth + 2)
+
+ elif isinstance(item, (ast.AST, ast3.AST, ast27.AST)):
+ yield from _stringify_ast(item, depth + 2)
+ elif isinstance(value, (ast.AST, ast3.AST, ast27.AST)):
+ yield from _stringify_ast(value, depth + 2)
+
+ else:
+ # Constant strings may be indented across newlines, if they are
+ # docstrings; fold spaces after newlines when comparing
+ 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 = parse_ast(src)
except Exception as exc:
raise AssertionError(
- f"cannot use --safe with this file; failed to parse source file. "
- f"AST error message: {exc}"
+ "cannot use --safe with this file; failed to parse source file. AST"
+ f" error message: {exc}"
)
try:
except Exception as exc:
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/python/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"))
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/python/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, mode: FileMode) -> None:
+def assert_stable(src: str, dst: str, mode: Mode) -> None:
"""Raise AssertionError if `dst` reformats differently the second time."""
newdst = format_str(dst, mode=mode)
if dst != newdst:
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/python/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:
"""Dump `output` to a temporary file. Return path to the file."""
with tempfile.NamedTemporaryFile(
return f.name
+@contextmanager
+def nullcontext() -> Iterator[None]:
+ """Return an empty context manager.
+
+ To be used like `nullcontext` in Python 3.7.
+ """
+ yield
+
+
def diff(a: str, b: str, a_name: str, b_name: str) -> str:
"""Return a unified diff string between strings `a` and `b`."""
import difflib
- a_lines = [line + "\n" for line in a.split("\n")]
- b_lines = [line + "\n" for line in b.split("\n")]
+ 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)
)
-def cancel(tasks: Iterable[asyncio.Task]) -> None:
+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:
"""
if "\n" in regex:
regex = "(?x)" + regex
- return re.compile(regex)
+ compiled: Pattern[str] = re.compile(regex)
+ return compiled
def enumerate_reversed(sequence: Sequence[T]) -> Iterator[Tuple[Index, T]]:
Uses the provided `line_str` rendering, if any, otherwise computes a new one.
"""
if not line_str:
- line_str = str(line).strip("\n")
+ line_str = line_to_string(line)
return (
len(line_str) <= line_length
and "\n" not in line_str # multiline strings
return False
-def get_cache_file(mode: FileMode) -> Path:
+def get_cache_file(mode: Mode) -> Path:
return CACHE_DIR / f"cache.{mode.get_cache_key()}.pickle"
-def read_cache(mode: FileMode) -> Cache:
+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.
with cache_file.open("rb") as fobj:
try:
cache: Cache = pickle.load(fobj)
- except pickle.UnpicklingError:
+ except (pickle.UnpicklingError, ValueError):
return {}
return cache
return todo, done
-def write_cache(cache: Cache, sources: Iterable[Path], mode: FileMode) -> None:
+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=pickle.HIGHEST_PROTOCOL)
+ pickle.dump(new_cache, f, protocol=4)
os.replace(f.name, cache_file)
except OSError:
pass
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