changelog: make copies related function return None or a valid value
With the previous code, existing but empty value were not "decoded", leading to
the method returning one of `None`, some valid value (`list` or `dict`) or
`b''`.
On a general basis, not explicitly checking for None is a source of bugs.
Having a clean return types will help the side-data copies code in future
changesets.
Differential Revision: https://phab.mercurial-scm.org/D7037
# no-check-code because 3rd party
import ast
import asyncio
from concurrent.futures import Executor, ProcessPoolExecutor
from contextlib import contextmanager
from datetime import datetime
from enum import Enum
from functools import lru_cache, partial, wraps
import io
import itertools
import logging
from multiprocessing import Manager, freeze_support
import os
from pathlib import Path
import pickle
import re
import signal
import sys
import tempfile
import tokenize
import traceback
from typing import (
Any,
Callable,
Collection,
Dict,
Generator,
Generic,
Iterable,
Iterator,
List,
Optional,
Pattern,
Sequence,
Set,
Tuple,
TypeVar,
Union,
cast,
)
from appdirs import user_cache_dir
from attr import dataclass, evolve, Factory
import click
import toml
from typed_ast import ast3, ast27
# lib2to3 fork
from blib2to3.pytree import Node, Leaf, type_repr
from blib2to3 import pygram, pytree
from blib2to3.pgen2 import driver, token
from blib2to3.pgen2.grammar import Grammar
from blib2to3.pgen2.parse import ParseError
__version__ = '19.3b1.dev95+gdc1add6.d20191005'
DEFAULT_LINE_LENGTH = 88
DEFAULT_EXCLUDES = (
r"/(\.eggs|\.git|\.hg|\.mypy_cache|\.nox|\.tox|\.venv|_build|buck-out|build|dist)/"
)
DEFAULT_INCLUDES = r"\.pyi?$"
CACHE_DIR = Path(user_cache_dir("black", version=__version__))
# types
FileContent = str
Encoding = str
NewLine = str
Depth = int
NodeType = int
LeafID = int
Priority = int
Index = int
LN = Union[Leaf, Node]
SplitFunc = Callable[["Line", Collection["Feature"]], Iterator["Line"]]
Timestamp = float
FileSize = int
CacheInfo = Tuple[Timestamp, FileSize]
Cache = Dict[Path, CacheInfo]
out = partial(click.secho, bold=True, err=True)
err = partial(click.secho, fg="red", err=True)
pygram.initialize(CACHE_DIR)
syms = pygram.python_symbols
class NothingChanged(UserWarning):
"""Raised when reformatted code is the same as source."""
class CannotSplit(Exception):
"""A readable split that fits the allotted line length is impossible."""
class InvalidInput(ValueError):
"""Raised when input source code fails all parse attempts."""
class WriteBack(Enum):
NO = 0
YES = 1
DIFF = 2
CHECK = 3
@classmethod
def from_configuration(cls, *, check: bool, diff: bool) -> "WriteBack":
if check and not diff:
return cls.CHECK
return cls.DIFF if diff else cls.YES
class Changed(Enum):
NO = 0
CACHED = 1
YES = 2
class TargetVersion(Enum):
PY27 = 2
PY33 = 3
PY34 = 4
PY35 = 5
PY36 = 6
PY37 = 7
PY38 = 8
def is_python2(self) -> bool:
return self is TargetVersion.PY27
PY36_VERSIONS = {TargetVersion.PY36, TargetVersion.PY37, TargetVersion.PY38}
class Feature(Enum):
# All string literals are unicode
UNICODE_LITERALS = 1
F_STRINGS = 2
NUMERIC_UNDERSCORES = 3
TRAILING_COMMA_IN_CALL = 4
TRAILING_COMMA_IN_DEF = 5
# The following two feature-flags are mutually exclusive, and exactly one should be
# set for every version of python.
ASYNC_IDENTIFIERS = 6
ASYNC_KEYWORDS = 7
ASSIGNMENT_EXPRESSIONS = 8
POS_ONLY_ARGUMENTS = 9
VERSION_TO_FEATURES: Dict[TargetVersion, Set[Feature]] = {
TargetVersion.PY27: {Feature.ASYNC_IDENTIFIERS},
TargetVersion.PY33: {Feature.UNICODE_LITERALS, Feature.ASYNC_IDENTIFIERS},
TargetVersion.PY34: {Feature.UNICODE_LITERALS, Feature.ASYNC_IDENTIFIERS},
TargetVersion.PY35: {
Feature.UNICODE_LITERALS,
Feature.TRAILING_COMMA_IN_CALL,
Feature.ASYNC_IDENTIFIERS,
},
TargetVersion.PY36: {
Feature.UNICODE_LITERALS,
Feature.F_STRINGS,
Feature.NUMERIC_UNDERSCORES,
Feature.TRAILING_COMMA_IN_CALL,
Feature.TRAILING_COMMA_IN_DEF,
Feature.ASYNC_IDENTIFIERS,
},
TargetVersion.PY37: {
Feature.UNICODE_LITERALS,
Feature.F_STRINGS,
Feature.NUMERIC_UNDERSCORES,
Feature.TRAILING_COMMA_IN_CALL,
Feature.TRAILING_COMMA_IN_DEF,
Feature.ASYNC_KEYWORDS,
},
TargetVersion.PY38: {
Feature.UNICODE_LITERALS,
Feature.F_STRINGS,
Feature.NUMERIC_UNDERSCORES,
Feature.TRAILING_COMMA_IN_CALL,
Feature.TRAILING_COMMA_IN_DEF,
Feature.ASYNC_KEYWORDS,
Feature.ASSIGNMENT_EXPRESSIONS,
Feature.POS_ONLY_ARGUMENTS,
},
}
@dataclass
class FileMode:
target_versions: Set[TargetVersion] = Factory(set)
line_length: int = DEFAULT_LINE_LENGTH
string_normalization: bool = True
is_pyi: bool = False
def get_cache_key(self) -> str:
if self.target_versions:
version_str = ",".join(
str(version.value)
for version in sorted(self.target_versions, key=lambda v: v.value)
)
else:
version_str = "-"
parts = [
version_str,
str(self.line_length),
str(int(self.string_normalization)),
str(int(self.is_pyi)),
]
return ".".join(parts)
def supports_feature(target_versions: Set[TargetVersion], feature: Feature) -> bool:
return all(feature in VERSION_TO_FEATURES[version] for version in target_versions)
def read_pyproject_toml(
ctx: click.Context, param: click.Parameter, value: Union[str, int, bool, None]
) -> 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:
return None
try:
pyproject_toml = toml.load(value)
config = pyproject_toml.get("tool", {}).get("black", {})
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()}
)
return value
@click.command(context_settings=dict(help_option_names=["-h", "--help"]))
@click.option("-c", "--code", type=str, help="Format the code passed in as a string.")
@click.option(
"-l",
"--line-length",
type=int,
default=DEFAULT_LINE_LENGTH,
help="How many characters per line to allow.",
show_default=True,
)
@click.option(
"-t",
"--target-version",
type=click.Choice([v.name.lower() for v in TargetVersion]),
callback=lambda c, p, v: [TargetVersion[val.upper()] for val in v],
multiple=True,
help=(
"Python versions that should be supported by Black's output. [default: "
"per-file auto-detection]"
),
)
@click.option(
"--py36",
is_flag=True,
help=(
"Allow using Python 3.6-only syntax on all input files. This will put "
"trailing commas in function signatures and calls also after *args and "
"**kwargs. Deprecated; use --target-version instead. "
"[default: per-file auto-detection]"
),
)
@click.option(
"--pyi",
is_flag=True,
help=(
"Format all input files like typing stubs regardless of file extension "
"(useful when piping source on standard input)."
),
)
@click.option(
"-S",
"--skip-string-normalization",
is_flag=True,
help="Don't normalize string quotes or prefixes.",
)
@click.option(
"--check",
is_flag=True,
help=(
"Don't write the files back, just return the status. Return code 0 "
"means nothing would change. Return code 1 means some files would be "
"reformatted. Return code 123 means there was an internal error."
),
)
@click.option(
"--diff",
is_flag=True,
help="Don't write the files back, just output a diff for each file on stdout.",
)
@click.option(
"--fast/--safe",
is_flag=True,
help="If --fast given, skip temporary sanity checks. [default: --safe]",
)
@click.option(
"--include",
type=str,
default=DEFAULT_INCLUDES,
help=(
"A regular expression that matches files and directories that should be "
"included on recursive searches. An empty value means all files are "
"included regardless of the name. Use forward slashes for directories on "
"all platforms (Windows, too). Exclusions are calculated first, inclusions "
"later."
),
show_default=True,
)
@click.option(
"--exclude",
type=str,
default=DEFAULT_EXCLUDES,
help=(
"A regular expression that matches files and directories that should be "
"excluded on recursive searches. An empty value means no paths are excluded. "
"Use forward slashes for directories on all platforms (Windows, too). "
"Exclusions are calculated first, inclusions later."
),
show_default=True,
)
@click.option(
"-q",
"--quiet",
is_flag=True,
help=(
"Don't emit non-error messages to stderr. Errors are still emitted; "
"silence those with 2>/dev/null."
),
)
@click.option(
"-v",
"--verbose",
is_flag=True,
help=(
"Also emit messages to stderr about files that were not changed or were "
"ignored due to --exclude=."
),
)
@click.version_option(version=__version__)
@click.argument(
"src",
nargs=-1,
type=click.Path(
exists=True, file_okay=True, dir_okay=True, readable=True, allow_dash=True
),
is_eager=True,
)
@click.option(
"--config",
type=click.Path(
exists=False, file_okay=True, dir_okay=False, readable=True, allow_dash=False
),
is_eager=True,
callback=read_pyproject_toml,
help="Read configuration from PATH.",
)
@click.pass_context
def main(
ctx: click.Context,
code: Optional[str],
line_length: int,
target_version: List[TargetVersion],
check: bool,
diff: bool,
fast: bool,
pyi: bool,
py36: bool,
skip_string_normalization: bool,
quiet: bool,
verbose: bool,
include: str,
exclude: str,
src: Tuple[str],
config: Optional[str],
) -> None:
"""The uncompromising code formatter."""
write_back = WriteBack.from_configuration(check=check, diff=diff)
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
else:
# We'll autodetect later.
versions = set()
mode = FileMode(
target_versions=versions,
line_length=line_length,
is_pyi=pyi,
string_normalization=not skip_string_normalization,
)
if config and verbose:
out(f"Using configuration from {config}.", bold=False, fg="blue")
if code is not None:
print(format_str(code, mode=mode))
ctx.exit(0)
try:
include_regex = re_compile_maybe_verbose(include)
except re.error:
err(f"Invalid regular expression for include given: {include!r}")
ctx.exit(2)
try:
exclude_regex = re_compile_maybe_verbose(exclude)
except re.error:
err(f"Invalid regular expression for exclude given: {exclude!r}")
ctx.exit(2)
report = Report(check=check, quiet=quiet, verbose=verbose)
root = find_project_root(src)
sources: Set[Path] = set()
path_empty(src, quiet, verbose, ctx)
for s in src:
p = Path(s)
if p.is_dir():
sources.update(
gen_python_files_in_dir(p, root, include_regex, exclude_regex, report)
)
elif p.is_file() or s == "-":
# if a file was explicitly given, we don't care about its extension
sources.add(p)
else:
err(f"invalid path: {s}")
if len(sources) == 0:
if verbose or not quiet:
out("No Python files are present to be formatted. Nothing to do 😴")
ctx.exit(0)
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: Tuple[str], quiet: bool, verbose: bool, ctx: click.Context) -> None:
"""
Exit if there is no `src` provided for formatting
"""
if not src:
if verbose or not quiet:
out("No Path provided. Nothing to do 😴")
ctx.exit(0)
def reformat_one(
src: Path, fast: bool, write_back: WriteBack, mode: FileMode, report: "Report"
) -> None:
"""Reformat a single file under `src` without spawning child processes.
`fast`, `write_back`, and `mode` options are passed to
:func:`format_file_in_place` or :func:`format_stdin_to_stdout`.
"""
try:
changed = Changed.NO
if not src.is_file() and str(src) == "-":
if format_stdin_to_stdout(fast=fast, write_back=write_back, mode=mode):
changed = Changed.YES
else:
cache: Cache = {}
if write_back != WriteBack.DIFF:
cache = read_cache(mode)
res_src = src.resolve()
if res_src in cache and cache[res_src] == get_cache_info(res_src):
changed = Changed.CACHED
if changed is not Changed.CACHED and format_file_in_place(
src, fast=fast, write_back=write_back, mode=mode
):
changed = Changed.YES
if (write_back is WriteBack.YES and changed is not Changed.CACHED) or (
write_back is WriteBack.CHECK and changed is Changed.NO
):
write_cache(cache, [src], mode)
report.done(src, changed)
except Exception as exc:
report.failed(src, str(exc))
def reformat_many(
sources: Set[Path],
fast: bool,
write_back: WriteBack,
mode: FileMode,
report: "Report",
) -> None:
"""Reformat multiple files using a ProcessPoolExecutor."""
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:
loop.run_until_complete(
schedule_formatting(
sources=sources,
fast=fast,
write_back=write_back,
mode=mode,
report=report,
loop=loop,
executor=executor,
)
)
finally:
shutdown(loop)
executor.shutdown()
async def schedule_formatting(
sources: Set[Path],
fast: bool,
write_back: WriteBack,
mode: FileMode,
report: "Report",
loop: asyncio.AbstractEventLoop,
executor: Executor,
) -> None:
"""Run formatting of `sources` in parallel using the provided `executor`.
(Use ProcessPoolExecutors for actual parallelism.)
`write_back`, `fast`, and `mode` options are passed to
:func:`format_file_in_place`.
"""
cache: Cache = {}
if write_back != WriteBack.DIFF:
cache = read_cache(mode)
sources, cached = filter_cached(cache, sources)
for src in sorted(cached):
report.done(src, Changed.CACHED)
if not sources:
return
cancelled = []
sources_to_cache = []
lock = None
if write_back == WriteBack.DIFF:
# For diff output, we need locks to ensure we don't interleave output
# from different processes.
manager = Manager()
lock = manager.Lock()
tasks = {
asyncio.ensure_future(
loop.run_in_executor(
executor, format_file_in_place, src, fast, mode, write_back, lock
)
): src
for src in sorted(sources)
}
pending: Iterable[asyncio.Future] = tasks.keys()
try:
loop.add_signal_handler(signal.SIGINT, cancel, pending)
loop.add_signal_handler(signal.SIGTERM, cancel, pending)
except NotImplementedError:
# There are no good alternatives for these on Windows.
pass
while pending:
done, _ = await asyncio.wait(pending, return_when=asyncio.FIRST_COMPLETED)
for task in done:
src = tasks.pop(task)
if task.cancelled():
cancelled.append(task)
elif task.exception():
report.failed(src, str(task.exception()))
else:
changed = Changed.YES if task.result() else Changed.NO
# If the file was written back or was successfully checked as
# well-formatted, store this information in the cache.
if write_back is WriteBack.YES or (
write_back is WriteBack.CHECK and changed is Changed.NO
):
sources_to_cache.append(src)
report.done(src, changed)
if cancelled:
await asyncio.gather(*cancelled, loop=loop, return_exceptions=True)
if sources_to_cache:
write_cache(cache, sources_to_cache, mode)
def format_file_in_place(
src: Path,
fast: bool,
mode: FileMode,
write_back: WriteBack = WriteBack.NO,
lock: Any = None, # multiprocessing.Manager().Lock() is some crazy proxy
) -> bool:
"""Format file under `src` path. Return True if changed.
If `write_back` is DIFF, write a diff to stdout. If it is YES, write reformatted
code to the file.
`mode` and `fast` options are passed to :func:`format_file_contents`.
"""
if src.suffix == ".pyi":
mode = evolve(mode, is_pyi=True)
then = datetime.utcfromtimestamp(src.stat().st_mtime)
with open(src, "rb") as buf:
src_contents, encoding, newline = decode_bytes(buf.read())
try:
dst_contents = format_file_contents(src_contents, fast=fast, mode=mode)
except NothingChanged:
return False
if write_back == write_back.YES:
with open(src, "w", encoding=encoding, newline=newline) as f:
f.write(dst_contents)
elif write_back == write_back.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)
with lock or nullcontext():
f = io.TextIOWrapper(
sys.stdout.buffer,
encoding=encoding,
newline=newline,
write_through=True,
)
f.write(diff_contents)
f.detach()
return True
def format_stdin_to_stdout(
fast: bool, *, write_back: WriteBack = WriteBack.NO, mode: FileMode
) -> bool:
"""Format file on stdin. Return True if changed.
If `write_back` is YES, write reformatted code back to stdout. If it is DIFF,
write a diff to stdout. The `mode` argument is passed to
:func:`format_file_contents`.
"""
then = datetime.utcnow()
src, encoding, newline = decode_bytes(sys.stdin.buffer.read())
dst = src
try:
dst = format_file_contents(src, fast=fast, mode=mode)
return True
except NothingChanged:
return False
finally:
f = io.TextIOWrapper(
sys.stdout.buffer, encoding=encoding, newline=newline, write_through=True
)
if write_back == WriteBack.YES:
f.write(dst)
elif write_back == WriteBack.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))
f.detach()
def format_file_contents(
src_contents: str, *, fast: bool, mode: FileMode
) -> FileContent:
"""Reformat contents a file and return new contents.
If `fast` is False, additionally confirm that the reformatted code is
valid by calling :func:`assert_equivalent` and :func:`assert_stable` on it.
`mode` is passed to :func:`format_str`.
"""
if src_contents.strip() == "":
raise NothingChanged
dst_contents = format_str(src_contents, mode=mode)
if src_contents == dst_contents:
raise NothingChanged
if not fast:
assert_equivalent(src_contents, dst_contents)
assert_stable(src_contents, dst_contents, mode=mode)
return dst_contents
def format_str(src_contents: str, *, mode: FileMode) -> FileContent:
"""Reformat a string and return new contents.
`mode` determines formatting options, such as how many characters per line are
allowed.
"""
src_node = lib2to3_parse(src_contents.lstrip(), mode.target_versions)
dst_contents = []
future_imports = get_future_imports(src_node)
if mode.target_versions:
versions = mode.target_versions
else:
versions = detect_target_versions(src_node)
normalize_fmt_off(src_node)
lines = LineGenerator(
remove_u_prefix="unicode_literals" in future_imports
or supports_feature(versions, Feature.UNICODE_LITERALS),
is_pyi=mode.is_pyi,
normalize_strings=mode.string_normalization,
)
elt = EmptyLineTracker(is_pyi=mode.is_pyi)
empty_line = Line()
after = 0
split_line_features = {
feature
for feature in {Feature.TRAILING_COMMA_IN_CALL, Feature.TRAILING_COMMA_IN_DEF}
if supports_feature(versions, feature)
}
for current_line in lines.visit(src_node):
for _ in range(after):
dst_contents.append(str(empty_line))
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(line))
return "".join(dst_contents)
def decode_bytes(src: bytes) -> Tuple[FileContent, Encoding, NewLine]:
"""Return a tuple of (decoded_contents, encoding, newline).
`newline` is either CRLF or LF but `decoded_contents` is decoded with
universal newlines (i.e. only contains LF).
"""
srcbuf = io.BytesIO(src)
encoding, lines = tokenize.detect_encoding(srcbuf.readline)
if not lines:
return "", encoding, "\n"
newline = "\r\n" if b"\r\n" == lines[0][-2:] else "\n"
srcbuf.seek(0)
with io.TextIOWrapper(srcbuf, encoding) as tiow:
return tiow.read(), encoding, newline
def get_grammars(target_versions: Set[TargetVersion]) -> List[Grammar]:
if not target_versions:
# No target_version specified, so try all grammars.
return [
# Python 3.7+
pygram.python_grammar_no_print_statement_no_exec_statement_async_keywords,
# Python 3.0-3.6
pygram.python_grammar_no_print_statement_no_exec_statement,
# Python 2.7 with future print_function import
pygram.python_grammar_no_print_statement,
# Python 2.7
pygram.python_grammar,
]
elif all(version.is_python2() for version in target_versions):
# Python 2-only code, so try Python 2 grammars.
return [
# Python 2.7 with future print_function import
pygram.python_grammar_no_print_statement,
# Python 2.7
pygram.python_grammar,
]
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
def lib2to3_parse(src_txt: str, target_versions: Iterable[TargetVersion] = ()) -> Node:
"""Given a string with source, return the lib2to3 Node."""
if src_txt[-1:] != "\n":
src_txt += "\n"
for grammar in get_grammars(set(target_versions)):
drv = driver.Driver(grammar, pytree.convert)
try:
result = drv.parse_string(src_txt, True)
break
except ParseError as pe:
lineno, column = pe.context[1]
lines = src_txt.splitlines()
try:
faulty_line = lines[lineno - 1]
except IndexError:
faulty_line = "<line number missing in source>"
exc = InvalidInput(f"Cannot parse: {lineno}:{column}: {faulty_line}")
else:
raise exc from None
if isinstance(result, Leaf):
result = Node(syms.file_input, [result])
return result
def lib2to3_unparse(node: Node) -> str:
"""Given a lib2to3 node, return its string representation."""
code = str(node)
return code
T = TypeVar("T")
class Visitor(Generic[T]):
"""Basic lib2to3 visitor that yields things of type `T` on `visit()`."""
def visit(self, node: LN) -> Iterator[T]:
"""Main method to visit `node` and its children.
It tries to find a `visit_*()` method for the given `node.type`, like
`visit_simple_stmt` for Node objects or `visit_INDENT` for Leaf objects.
If no dedicated `visit_*()` method is found, chooses `visit_default()`
instead.
Then yields objects of type `T` from the selected visitor.
"""
if node.type < 256:
name = token.tok_name[node.type]
else:
name = type_repr(node.type)
yield from getattr(self, f"visit_{name}", self.visit_default)(node)
def visit_default(self, node: LN) -> Iterator[T]:
"""Default `visit_*()` implementation. Recurses to children of `node`."""
if isinstance(node, Node):
for child in node.children:
yield from self.visit(child)
@dataclass
class DebugVisitor(Visitor[T]):
tree_depth: int = 0
def visit_default(self, node: LN) -> Iterator[T]:
indent = " " * (2 * self.tree_depth)
if isinstance(node, Node):
_type = type_repr(node.type)
out(f"{indent}{_type}", fg="yellow")
self.tree_depth += 1
for child in node.children:
yield from self.visit(child)
self.tree_depth -= 1
out(f"{indent}/{_type}", fg="yellow", bold=False)
else:
_type = token.tok_name.get(node.type, str(node.type))
out(f"{indent}{_type}", fg="blue", nl=False)
if node.prefix:
# We don't have to handle prefixes for `Node` objects since
# that delegates to the first child anyway.
out(f" {node.prefix!r}", fg="green", bold=False, nl=False)
out(f" {node.value!r}", fg="blue", bold=False)
@classmethod
def show(cls, code: Union[str, Leaf, Node]) -> None:
"""Pretty-print the lib2to3 AST of a given string of `code`.
Convenience method for debugging.
"""
v: DebugVisitor[None] = DebugVisitor()
if isinstance(code, str):
code = lib2to3_parse(code)
list(v.visit(code))
WHITESPACE = {token.DEDENT, token.INDENT, token.NEWLINE}
STATEMENT = {
syms.if_stmt,
syms.while_stmt,
syms.for_stmt,
syms.try_stmt,
syms.except_clause,
syms.with_stmt,
syms.funcdef,
syms.classdef,
}
STANDALONE_COMMENT = 153
token.tok_name[STANDALONE_COMMENT] = "STANDALONE_COMMENT"
LOGIC_OPERATORS = {"and", "or"}
COMPARATORS = {
token.LESS,
token.GREATER,
token.EQEQUAL,
token.NOTEQUAL,
token.LESSEQUAL,
token.GREATEREQUAL,
}
MATH_OPERATORS = {
token.VBAR,
token.CIRCUMFLEX,
token.AMPER,
token.LEFTSHIFT,
token.RIGHTSHIFT,
token.PLUS,
token.MINUS,
token.STAR,
token.SLASH,
token.DOUBLESLASH,
token.PERCENT,
token.AT,
token.TILDE,
token.DOUBLESTAR,
}
STARS = {token.STAR, token.DOUBLESTAR}
VARARGS_SPECIALS = STARS | {token.SLASH}
VARARGS_PARENTS = {
syms.arglist,
syms.argument, # double star in arglist
syms.trailer, # single argument to call
syms.typedargslist,
syms.varargslist, # lambdas
}
UNPACKING_PARENTS = {
syms.atom, # single element of a list or set literal
syms.dictsetmaker,
syms.listmaker,
syms.testlist_gexp,
syms.testlist_star_expr,
}
TEST_DESCENDANTS = {
syms.test,
syms.lambdef,
syms.or_test,
syms.and_test,
syms.not_test,
syms.comparison,
syms.star_expr,
syms.expr,
syms.xor_expr,
syms.and_expr,
syms.shift_expr,
syms.arith_expr,
syms.trailer,
syms.term,
syms.power,
}
ASSIGNMENTS = {
"=",
"+=",
"-=",
"*=",
"@=",
"/=",
"%=",
"&=",
"|=",
"^=",
"<<=",
">>=",
"**=",
"//=",
}
COMPREHENSION_PRIORITY = 20
COMMA_PRIORITY = 18
TERNARY_PRIORITY = 16
LOGIC_PRIORITY = 14
STRING_PRIORITY = 12
COMPARATOR_PRIORITY = 10
MATH_PRIORITIES = {
token.VBAR: 9,
token.CIRCUMFLEX: 8,
token.AMPER: 7,
token.LEFTSHIFT: 6,
token.RIGHTSHIFT: 6,
token.PLUS: 5,
token.MINUS: 5,
token.STAR: 4,
token.SLASH: 4,
token.DOUBLESLASH: 4,
token.PERCENT: 4,
token.AT: 4,
token.TILDE: 3,
token.DOUBLESTAR: 2,
}
DOT_PRIORITY = 1
@dataclass
class BracketTracker:
"""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)
previous: Optional[Leaf] = None
_for_loop_depths: List[int] = Factory(list)
_lambda_argument_depths: List[int] = Factory(list)
def mark(self, leaf: Leaf) -> None:
"""Mark `leaf` with bracket-related metadata. Keep track of delimiters.
All leaves receive an int `bracket_depth` field that stores how deep
within brackets a given leaf is. 0 means there are no enclosing brackets
that started on this line.
If a leaf is itself a closing bracket, it receives an `opening_bracket`
field that it forms a pair with. This is a one-directional link to
avoid reference cycles.
If a leaf is a delimiter (a token on which Black can split the line if
needed) and it's on depth 0, its `id()` is stored in the tracker's
`delimiters` field.
"""
if leaf.type == token.COMMENT:
return
self.maybe_decrement_after_for_loop_variable(leaf)
self.maybe_decrement_after_lambda_arguments(leaf)
if leaf.type in CLOSING_BRACKETS:
self.depth -= 1
opening_bracket = self.bracket_match.pop((self.depth, leaf.type))
leaf.opening_bracket = opening_bracket
leaf.bracket_depth = self.depth
if self.depth == 0:
delim = is_split_before_delimiter(leaf, self.previous)
if delim and self.previous is not None:
self.delimiters[id(self.previous)] = delim
else:
delim = is_split_after_delimiter(leaf, self.previous)
if delim:
self.delimiters[id(leaf)] = delim
if leaf.type in OPENING_BRACKETS:
self.bracket_match[self.depth, BRACKET[leaf.type]] = leaf
self.depth += 1
self.previous = leaf
self.maybe_increment_lambda_arguments(leaf)
self.maybe_increment_for_loop_variable(leaf)
def any_open_brackets(self) -> bool:
"""Return True if there is an yet unmatched open bracket on the line."""
return bool(self.bracket_match)
def max_delimiter_priority(self, exclude: Iterable[LeafID] = ()) -> Priority:
"""Return the highest priority of a delimiter found on the line.
Values are consistent with what `is_split_*_delimiter()` return.
Raises ValueError on no delimiters.
"""
return max(v for k, v in self.delimiters.items() if k not in exclude)
def delimiter_count_with_priority(self, priority: Priority = 0) -> int:
"""Return the number of delimiters with the given `priority`.
If no `priority` is passed, defaults to max priority on the line.
"""
if not self.delimiters:
return 0
priority = priority or self.max_delimiter_priority()
return sum(1 for p in self.delimiters.values() if p == priority)
def maybe_increment_for_loop_variable(self, leaf: Leaf) -> bool:
"""In a for loop, or comprehension, the variables are often unpacks.
To avoid splitting on the comma in this situation, increase the depth of
tokens between `for` and `in`.
"""
if leaf.type == token.NAME and leaf.value == "for":
self.depth += 1
self._for_loop_depths.append(self.depth)
return True
return False
def maybe_decrement_after_for_loop_variable(self, leaf: Leaf) -> bool:
"""See `maybe_increment_for_loop_variable` above for explanation."""
if (
self._for_loop_depths
and self._for_loop_depths[-1] == self.depth
and leaf.type == token.NAME
and leaf.value == "in"
):
self.depth -= 1
self._for_loop_depths.pop()
return True
return False
def maybe_increment_lambda_arguments(self, leaf: Leaf) -> bool:
"""In a lambda expression, there might be more than one argument.
To avoid splitting on the comma in this situation, increase the depth of
tokens between `lambda` and `:`.
"""
if leaf.type == token.NAME and leaf.value == "lambda":
self.depth += 1
self._lambda_argument_depths.append(self.depth)
return True
return False
def maybe_decrement_after_lambda_arguments(self, leaf: Leaf) -> bool:
"""See `maybe_increment_lambda_arguments` above for explanation."""
if (
self._lambda_argument_depths
and self._lambda_argument_depths[-1] == self.depth
and leaf.type == token.COLON
):
self.depth -= 1
self._lambda_argument_depths.pop()
return True
return False
def get_open_lsqb(self) -> Optional[Leaf]:
"""Return the most recent opening square bracket (if any)."""
return self.bracket_match.get((self.depth - 1, token.RSQB))
@dataclass
class Line:
"""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)
inside_brackets: bool = False
should_explode: bool = False
def append(self, leaf: Leaf, preformatted: bool = False) -> None:
"""Add a new `leaf` to the end of the line.
Unless `preformatted` is True, the `leaf` will receive a new consistent
whitespace prefix and metadata applied by :class:`BracketTracker`.
Trailing commas are maybe removed, unpacked for loop variables are
demoted from being delimiters.
Inline comments are put aside.
"""
has_value = leaf.type in BRACKETS or bool(leaf.value.strip())
if not has_value:
return
if token.COLON == leaf.type and self.is_class_paren_empty:
del self.leaves[-2:]
if self.leaves and not preformatted:
# Note: at this point leaf.prefix should be empty except for
# imports, for which we only preserve newlines.
leaf.prefix += whitespace(
leaf, complex_subscript=self.is_complex_subscript(leaf)
)
if self.inside_brackets or not preformatted:
self.bracket_tracker.mark(leaf)
self.maybe_remove_trailing_comma(leaf)
if not self.append_comment(leaf):
self.leaves.append(leaf)
def append_safe(self, leaf: Leaf, preformatted: bool = False) -> None:
"""Like :func:`append()` but disallow invalid standalone comment structure.
Raises ValueError when any `leaf` is appended after a standalone comment
or when a standalone comment is not the first leaf on the line.
"""
if self.bracket_tracker.depth == 0:
if self.is_comment:
raise ValueError("cannot append to standalone comments")
if self.leaves and leaf.type == STANDALONE_COMMENT:
raise ValueError(
"cannot append standalone comments to a populated line"
)
self.append(leaf, preformatted=preformatted)
@property
def is_comment(self) -> bool:
"""Is this line a standalone comment?"""
return len(self.leaves) == 1 and self.leaves[0].type == STANDALONE_COMMENT
@property
def is_decorator(self) -> bool:
"""Is this line a decorator?"""
return bool(self) and self.leaves[0].type == token.AT
@property
def is_import(self) -> bool:
"""Is this an import line?"""
return bool(self) and is_import(self.leaves[0])
@property
def is_class(self) -> bool:
"""Is this line a class definition?"""
return (
bool(self)
and self.leaves[0].type == token.NAME
and self.leaves[0].value == "class"
)
@property
def is_stub_class(self) -> bool:
"""Is this line a class definition with a body consisting only of "..."?"""
return self.is_class and self.leaves[-3:] == [
Leaf(token.DOT, ".") for _ in range(3)
]
@property
def is_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.)"""
try:
first_leaf = self.leaves[0]
except IndexError:
return False
try:
second_leaf: Optional[Leaf] = self.leaves[1]
except IndexError:
second_leaf = None
return (first_leaf.type == token.NAME and first_leaf.value == "def") or (
first_leaf.type == token.ASYNC
and second_leaf is not None
and second_leaf.type == token.NAME
and second_leaf.value == "def"
)
@property
def is_class_paren_empty(self) -> bool:
"""Is this a class with no base classes but using parentheses?
Those are unnecessary and should be removed.
"""
return (
bool(self)
and len(self.leaves) == 4
and self.is_class
and self.leaves[2].type == token.LPAR
and self.leaves[2].value == "("
and self.leaves[3].type == token.RPAR
and self.leaves[3].value == ")"
)
@property
def is_triple_quoted_string(self) -> bool:
"""Is the line a triple quoted string?"""
return (
bool(self)
and self.leaves[0].type == token.STRING
and self.leaves[0].value.startswith(('"""', "'''"))
)
def contains_standalone_comments(self, depth_limit: int = sys.maxsize) -> bool:
"""If so, needs to be split before emitting."""
for leaf in self.leaves:
if leaf.type == STANDALONE_COMMENT:
if leaf.bracket_depth <= depth_limit:
return True
return False
def contains_uncollapsable_type_comments(self) -> bool:
ignored_ids = set()
try:
last_leaf = self.leaves[-1]
ignored_ids.add(id(last_leaf))
if last_leaf.type == token.COMMA or (
last_leaf.type == token.RPAR and not last_leaf.value
):
# When trailing commas or optional parens are inserted by Black for
# consistency, comments after the previous last element are not moved
# (they don't have to, rendering will still be correct). So we ignore
# trailing commas and invisible.
last_leaf = self.leaves[-2]
ignored_ids.add(id(last_leaf))
except IndexError:
return False
# A type comment is uncollapsable if it is attached to a leaf
# that isn't at the end of the line (since that could cause it
# to get associated to a different argument) or if there are
# comments before it (since that could cause it to get hidden
# behind a comment.
comment_seen = False
for leaf_id, comments in self.comments.items():
for comment in comments:
if is_type_comment(comment):
if leaf_id not in ignored_ids or comment_seen:
return True
comment_seen = True
return False
def contains_unsplittable_type_ignore(self) -> bool:
if not self.leaves:
return False
# If a 'type: ignore' is attached to the end of a line, we
# can't split the line, because we can't know which of the
# subexpressions the ignore was meant to apply to.
#
# We only want this to apply to actual physical lines from the
# original source, though: we don't want the presence of a
# 'type: ignore' at the end of a multiline expression to
# justify pushing it all onto one line. Thus we
# (unfortunately) need to check the actual source lines and
# only report an unsplittable 'type: ignore' if this line was
# one line in the original code.
if self.leaves[0].lineno == self.leaves[-1].lineno:
for comment in self.comments.get(id(self.leaves[-1]), []):
if is_type_comment(comment, " ignore"):
return True
return False
def contains_multiline_strings(self) -> bool:
for leaf in self.leaves:
if is_multiline_string(leaf):
return True
return False
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
self.remove_trailing_comma()
return True
def append_comment(self, comment: Leaf) -> bool:
"""Add an inline or standalone comment to the line."""
if (
comment.type == STANDALONE_COMMENT
and self.bracket_tracker.any_open_brackets()
):
comment.prefix = ""
return False
if comment.type != token.COMMENT:
return False
if not self.leaves:
comment.type = STANDALONE_COMMENT
comment.prefix = ""
return False
last_leaf = self.leaves[-1]
if (
last_leaf.type == token.RPAR
and not last_leaf.value
and last_leaf.parent
and len(list(last_leaf.parent.leaves())) <= 3
and not is_type_comment(comment)
):
# Comments on an optional parens wrapping a single leaf should belong to
# the wrapped node except if it's a type comment. Pinning the comment like
# this avoids unstable formatting caused by comment migration.
if len(self.leaves) < 2:
comment.type = STANDALONE_COMMENT
comment.prefix = ""
return False
last_leaf = self.leaves[-2]
self.comments.setdefault(id(last_leaf), []).append(comment)
return True
def comments_after(self, leaf: Leaf) -> List[Leaf]:
"""Generate comments that should appear directly after `leaf`."""
return self.comments.get(id(leaf), [])
def remove_trailing_comma(self) -> None:
"""Remove the trailing comma and moves the comments attached to it."""
trailing_comma = self.leaves.pop()
trailing_comma_comments = self.comments.pop(id(trailing_comma), [])
self.comments.setdefault(id(self.leaves[-1]), []).extend(
trailing_comma_comments
)
def is_complex_subscript(self, leaf: Leaf) -> bool:
"""Return True iff `leaf` is part of a slice with non-trivial exprs."""
open_lsqb = self.bracket_tracker.get_open_lsqb()
if open_lsqb is None:
return False
subscript_start = open_lsqb.next_sibling
if isinstance(subscript_start, Node):
if subscript_start.type == syms.listmaker:
return False
if subscript_start.type == syms.subscriptlist:
subscript_start = child_towards(subscript_start, leaf)
return subscript_start is not None and any(
n.type in TEST_DESCENDANTS for n in subscript_start.pre_order()
)
def __str__(self) -> str:
"""Render the line."""
if not self:
return "\n"
indent = " " * self.depth
leaves = iter(self.leaves)
first = next(leaves)
res = f"{first.prefix}{indent}{first.value}"
for leaf in leaves:
res += str(leaf)
for comment in itertools.chain.from_iterable(self.comments.values()):
res += str(comment)
return res + "\n"
def __bool__(self) -> bool:
"""Return True if the line has leaves or comments."""
return bool(self.leaves or self.comments)
@dataclass
class EmptyLineTracker:
"""Provides a stateful method that returns the number of potential extra
empty lines needed before and after the currently processed line.
Note: this tracker works on lines that haven't been split yet. It assumes
the prefix of the first leaf consists of optional newlines. Those newlines
are consumed by `maybe_empty_lines()` and included in the computation.
"""
is_pyi: bool = False
previous_line: Optional[Line] = None
previous_after: int = 0
previous_defs: List[int] = Factory(list)
def maybe_empty_lines(self, current_line: Line) -> Tuple[int, int]:
"""Return the number of extra empty lines before and after the `current_line`.
This is for separating `def`, `async def` and `class` with extra empty
lines (two on module-level).
"""
before, after = self._maybe_empty_lines(current_line)
before = (
# Black should not insert empty lines at the beginning
# of the file
0
if self.previous_line is None
else before - self.previous_after
)
self.previous_after = after
self.previous_line = current_line
return before, after
def _maybe_empty_lines(self, current_line: Line) -> Tuple[int, int]:
max_allowed = 1
if current_line.depth == 0:
max_allowed = 1 if self.is_pyi else 2
if current_line.leaves:
# Consume the first leaf's extra newlines.
first_leaf = current_line.leaves[0]
before = first_leaf.prefix.count("\n")
before = min(before, max_allowed)
first_leaf.prefix = ""
else:
before = 0
depth = current_line.depth
while self.previous_defs and self.previous_defs[-1] >= depth:
self.previous_defs.pop()
if self.is_pyi:
before = 0 if depth else 1
else:
before = 1 if depth else 2
if current_line.is_decorator or current_line.is_def or current_line.is_class:
return self._maybe_empty_lines_for_class_or_def(current_line, before)
if (
self.previous_line
and self.previous_line.is_import
and not current_line.is_import
and depth == self.previous_line.depth
):
return (before or 1), 0
if (
self.previous_line
and self.previous_line.is_class
and current_line.is_triple_quoted_string
):
return before, 1
return before, 0
def _maybe_empty_lines_for_class_or_def(
self, current_line: Line, before: int
) -> Tuple[int, int]:
if not current_line.is_decorator:
self.previous_defs.append(current_line.depth)
if self.previous_line is None:
# Don't insert empty lines before the first line in the file.
return 0, 0
if self.previous_line.is_decorator:
return 0, 0
if self.previous_line.depth < current_line.depth and (
self.previous_line.is_class or self.previous_line.is_def
):
return 0, 0
if (
self.previous_line.is_comment
and self.previous_line.depth == current_line.depth
and before == 0
):
return 0, 0
if self.is_pyi:
if self.previous_line.depth > current_line.depth:
newlines = 1
elif current_line.is_class or self.previous_line.is_class:
if current_line.is_stub_class and self.previous_line.is_stub_class:
# No blank line between classes with an empty body
newlines = 0
else:
newlines = 1
elif current_line.is_def and not self.previous_line.is_def:
# Blank line between a block of functions and a block of non-functions
newlines = 1
else:
newlines = 0
else:
newlines = 2
if current_line.depth and newlines:
newlines -= 1
return newlines, 0
@dataclass
class LineGenerator(Visitor[Line]):
"""Generates reformatted Line objects. Empty lines are not emitted.
Note: destroys the tree it's visiting by mutating prefixes of its leaves
in ways that will no longer stringify to valid Python code on the tree.
"""
is_pyi: bool = False
normalize_strings: bool = True
current_line: Line = Factory(Line)
remove_u_prefix: bool = False
def line(self, indent: int = 0) -> Iterator[Line]:
"""Generate a line.
If the line is empty, only emit if it makes sense.
If the line is too long, split it first and then generate.
If any lines were generated, set up a new current_line.
"""
if not self.current_line:
self.current_line.depth += indent
return # Line is empty, don't emit. Creating a new one unnecessary.
complete_line = self.current_line
self.current_line = Line(depth=complete_line.depth + indent)
yield complete_line
def visit_default(self, node: LN) -> Iterator[Line]:
"""Default `visit_*()` implementation. Recurses to children of `node`."""
if isinstance(node, Leaf):
any_open_brackets = self.current_line.bracket_tracker.any_open_brackets()
for comment in generate_comments(node):
if any_open_brackets:
# any comment within brackets is subject to splitting
self.current_line.append(comment)
elif comment.type == token.COMMENT:
# regular trailing comment
self.current_line.append(comment)
yield from self.line()
else:
# regular standalone comment
yield from self.line()
self.current_line.append(comment)
yield from self.line()
normalize_prefix(node, inside_brackets=any_open_brackets)
if self.normalize_strings and node.type == token.STRING:
normalize_string_prefix(node, remove_u_prefix=self.remove_u_prefix)
normalize_string_quotes(node)
if node.type == token.NUMBER:
normalize_numeric_literal(node)
if node.type not in WHITESPACE:
self.current_line.append(node)
yield from super().visit_default(node)
def visit_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]:
"""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]:
"""Decrease indentation level, maybe yield a line."""
# The current line might still wait for trailing comments. At DEDENT time
# there won't be any (they would be prefixes on the preceding NEWLINE).
# Emit the line then.
yield from self.line()
# While DEDENT has no value, its prefix may contain standalone comments
# that belong to the current indentation level. Get 'em.
yield from self.visit_default(node)
# Finally, emit the dedent.
yield from self.line(-1)
def visit_stmt(
self, node: Node, keywords: Set[str], parens: Set[str]
) -> Iterator[Line]:
"""Visit a statement.
This implementation is shared for `if`, `while`, `for`, `try`, `except`,
`def`, `with`, `class`, `assert` and assignments.
The relevant Python language `keywords` for a given statement will be
NAME leaves within it. This methods puts those on a separate line.
`parens` holds a set of string leaf values immediately after which
invisible parens should be put.
"""
normalize_invisible_parens(node, parens_after=parens)
for child in node.children:
if child.type == token.NAME and child.value in keywords: # type: ignore
yield from self.line()
yield from self.visit(child)
def visit_suite(self, node: Node) -> Iterator[Line]:
"""Visit a suite."""
if self.is_pyi and is_stub_suite(node):
yield from self.visit(node.children[2])
else:
yield from self.visit_default(node)
def visit_simple_stmt(self, node: Node) -> Iterator[Line]:
"""Visit a statement without nested statements."""
is_suite_like = node.parent and node.parent.type in STATEMENT
if is_suite_like:
if self.is_pyi and is_stub_body(node):
yield from self.visit_default(node)
else:
yield from self.line(+1)
yield from self.visit_default(node)
yield from self.line(-1)
else:
if not self.is_pyi or not node.parent or not is_stub_suite(node.parent):
yield from self.line()
yield from self.visit_default(node)
def visit_async_stmt(self, node: Node) -> Iterator[Line]:
"""Visit `async def`, `async for`, `async with`."""
yield from self.line()
children = iter(node.children)
for child in children:
yield from self.visit(child)
if child.type == token.ASYNC:
break
internal_stmt = next(children)
for child in internal_stmt.children:
yield from self.visit(child)
def visit_decorators(self, node: Node) -> Iterator[Line]:
"""Visit decorators."""
for child in node.children:
yield from self.line()
yield from self.visit(child)
def visit_SEMI(self, leaf: Leaf) -> Iterator[Line]:
"""Remove a semicolon and put the other statement on a separate line."""
yield from self.line()
def visit_ENDMARKER(self, leaf: Leaf) -> Iterator[Line]:
"""End of file. Process outstanding comments and end with a newline."""
yield from self.visit_default(leaf)
yield from self.line()
def visit_STANDALONE_COMMENT(self, leaf: Leaf) -> Iterator[Line]:
if not self.current_line.bracket_tracker.any_open_brackets():
yield from self.line()
yield from self.visit_default(leaf)
def __attrs_post_init__(self) -> None:
"""You are in a twisty little maze of passages."""
v = self.visit_stmt
Ø: Set[str] = set()
self.visit_assert_stmt = partial(v, keywords={"assert"}, parens={"assert", ","})
self.visit_if_stmt = partial(
v, keywords={"if", "else", "elif"}, parens={"if", "elif"}
)
self.visit_while_stmt = partial(v, keywords={"while", "else"}, parens={"while"})
self.visit_for_stmt = partial(v, keywords={"for", "else"}, parens={"for", "in"})
self.visit_try_stmt = partial(
v, keywords={"try", "except", "else", "finally"}, parens=Ø
)
self.visit_except_clause = partial(v, keywords={"except"}, parens=Ø)
self.visit_with_stmt = partial(v, keywords={"with"}, parens=Ø)
self.visit_funcdef = partial(v, keywords={"def"}, parens=Ø)
self.visit_classdef = partial(v, keywords={"class"}, parens=Ø)
self.visit_expr_stmt = partial(v, keywords=Ø, parens=ASSIGNMENTS)
self.visit_return_stmt = partial(v, keywords={"return"}, parens={"return"})
self.visit_import_from = partial(v, keywords=Ø, parens={"import"})
self.visit_del_stmt = partial(v, keywords=Ø, parens={"del"})
self.visit_async_funcdef = self.visit_async_stmt
self.visit_decorated = self.visit_decorators
IMPLICIT_TUPLE = {syms.testlist, syms.testlist_star_expr, syms.exprlist}
BRACKET = {token.LPAR: token.RPAR, token.LSQB: token.RSQB, token.LBRACE: token.RBRACE}
OPENING_BRACKETS = set(BRACKET.keys())
CLOSING_BRACKETS = set(BRACKET.values())
BRACKETS = OPENING_BRACKETS | CLOSING_BRACKETS
ALWAYS_NO_SPACE = CLOSING_BRACKETS | {token.COMMA, STANDALONE_COMMENT}
def whitespace(leaf: Leaf, *, complex_subscript: bool) -> str: # noqa: C901
"""Return whitespace prefix if needed for the given `leaf`.
`complex_subscript` signals whether the given leaf is part of a subscription
which has non-trivial arguments, like arithmetic expressions or function calls.
"""
NO = ""
SPACE = " "
DOUBLESPACE = " "
t = leaf.type
p = leaf.parent
v = leaf.value
if t in ALWAYS_NO_SPACE:
return NO
if t == token.COMMENT:
return DOUBLESPACE
assert p is not None, f"INTERNAL ERROR: hand-made leaf without parent: {leaf!r}"
if t == token.COLON and p.type not in {
syms.subscript,
syms.subscriptlist,
syms.sliceop,
}:
return NO
prev = leaf.prev_sibling
if not prev:
prevp = preceding_leaf(p)
if not prevp or prevp.type in OPENING_BRACKETS:
return NO
if t == token.COLON:
if prevp.type == token.COLON:
return NO
elif prevp.type != token.COMMA and not complex_subscript:
return NO
return SPACE
if prevp.type == token.EQUAL:
if prevp.parent:
if prevp.parent.type in {
syms.arglist,
syms.argument,
syms.parameters,
syms.varargslist,
}:
return NO
elif prevp.parent.type == syms.typedargslist:
# A bit hacky: if the equal sign has whitespace, it means we
# previously found it's a typed argument. So, we're using
# that, too.
return prevp.prefix
elif prevp.type in VARARGS_SPECIALS:
if is_vararg(prevp, within=VARARGS_PARENTS | UNPACKING_PARENTS):
return NO
elif prevp.type == token.COLON:
if prevp.parent and prevp.parent.type in {syms.subscript, syms.sliceop}:
return SPACE if complex_subscript else NO
elif (
prevp.parent
and prevp.parent.type == syms.factor
and prevp.type in MATH_OPERATORS
):
return NO
elif (
prevp.type == token.RIGHTSHIFT
and prevp.parent
and prevp.parent.type == syms.shift_expr
and prevp.prev_sibling
and prevp.prev_sibling.type == token.NAME
and prevp.prev_sibling.value == "print" # type: ignore
):
# Python 2 print chevron
return NO
elif prev.type in OPENING_BRACKETS:
return NO
if p.type in {syms.parameters, syms.arglist}:
# untyped function signatures or calls
if not prev or prev.type != token.COMMA:
return NO
elif p.type == syms.varargslist:
# lambdas
if prev and prev.type != token.COMMA:
return NO
elif p.type == syms.typedargslist:
# typed function signatures
if not prev:
return NO
if t == token.EQUAL:
if prev.type != syms.tname:
return NO
elif prev.type == token.EQUAL:
# A bit hacky: if the equal sign has whitespace, it means we
# previously found it's a typed argument. So, we're using that, too.
return prev.prefix
elif prev.type != token.COMMA:
return NO
elif p.type == syms.tname:
# type names
if not prev:
prevp = preceding_leaf(p)
if not prevp or prevp.type != token.COMMA:
return NO
elif p.type == syms.trailer:
# attributes and calls
if t == token.LPAR or t == token.RPAR:
return NO
if not prev:
if t == token.DOT:
prevp = preceding_leaf(p)
if not prevp or prevp.type != token.NUMBER:
return NO
elif t == token.LSQB:
return NO
elif prev.type != token.COMMA:
return NO
elif p.type == syms.argument:
# single argument
if t == token.EQUAL:
return NO
if not prev:
prevp = preceding_leaf(p)
if not prevp or prevp.type == token.LPAR:
return NO
elif prev.type in {token.EQUAL} | VARARGS_SPECIALS:
return NO
elif p.type == syms.decorator:
# decorators
return NO
elif p.type == syms.dotted_name:
if prev:
return NO
prevp = preceding_leaf(p)
if not prevp or prevp.type == token.AT or prevp.type == token.DOT:
return NO
elif p.type == syms.classdef:
if t == token.LPAR:
return NO
if prev and prev.type == token.LPAR:
return NO
elif p.type in {syms.subscript, syms.sliceop}:
# indexing
if not prev:
assert p.parent is not None, "subscripts are always parented"
if p.parent.type == syms.subscriptlist:
return SPACE
return NO
elif not complex_subscript:
return NO
elif p.type == syms.atom:
if prev and t == token.DOT:
# dots, but not the first one.
return NO
elif p.type == syms.dictsetmaker:
# dict unpacking
if prev and prev.type == token.DOUBLESTAR:
return NO
elif p.type in {syms.factor, syms.star_expr}:
# unary ops
if not prev:
prevp = preceding_leaf(p)
if not prevp or prevp.type in OPENING_BRACKETS:
return NO
prevp_parent = prevp.parent
assert prevp_parent is not None
if prevp.type == token.COLON and prevp_parent.type in {
syms.subscript,
syms.sliceop,
}:
return NO
elif prevp.type == token.EQUAL and prevp_parent.type == syms.argument:
return NO
elif t in {token.NAME, token.NUMBER, token.STRING}:
return NO
elif p.type == syms.import_from:
if t == token.DOT:
if prev and prev.type == token.DOT:
return NO
elif t == token.NAME:
if v == "import":
return SPACE
if prev and prev.type == token.DOT:
return NO
elif p.type == syms.sliceop:
return NO
return SPACE
def preceding_leaf(node: Optional[LN]) -> Optional[Leaf]:
"""Return the first leaf that precedes `node`, if any."""
while node:
res = node.prev_sibling
if res:
if isinstance(res, Leaf):
return res
try:
return list(res.leaves())[-1]
except IndexError:
return None
node = node.parent
return None
def child_towards(ancestor: Node, descendant: LN) -> Optional[LN]:
"""Return the child of `ancestor` that contains `descendant`."""
node: Optional[LN] = descendant
while node and node.parent != ancestor:
node = node.parent
return node
def container_of(leaf: Leaf) -> LN:
"""Return `leaf` or one of its ancestors that is the topmost container of it.
By "container" we mean a node where `leaf` is the very first child.
"""
same_prefix = leaf.prefix
container: LN = leaf
while container:
parent = container.parent
if parent is None:
break
if parent.children[0].prefix != same_prefix:
break
if parent.type == syms.file_input:
break
if parent.prev_sibling is not None and parent.prev_sibling.type in BRACKETS:
break
container = parent
return container
def is_split_after_delimiter(leaf: Leaf, previous: Optional[Leaf] = None) -> Priority:
"""Return the priority of the `leaf` delimiter, given a line break after it.
The delimiter priorities returned here are from those delimiters that would
cause a line break after themselves.
Higher numbers are higher priority.
"""
if leaf.type == token.COMMA:
return COMMA_PRIORITY
return 0
def is_split_before_delimiter(leaf: Leaf, previous: Optional[Leaf] = None) -> Priority:
"""Return the priority of the `leaf` delimiter, given a line break before it.
The delimiter priorities returned here are from those delimiters that would
cause a line break before themselves.
Higher numbers are higher priority.
"""
if is_vararg(leaf, within=VARARGS_PARENTS | UNPACKING_PARENTS):
# * and ** might also be MATH_OPERATORS but in this case they are not.
# Don't treat them as a delimiter.
return 0
if (
leaf.type == token.DOT
and leaf.parent
and leaf.parent.type not in {syms.import_from, syms.dotted_name}
and (previous is None or previous.type in CLOSING_BRACKETS)
):
return DOT_PRIORITY
if (
leaf.type in MATH_OPERATORS
and leaf.parent
and leaf.parent.type not in {syms.factor, syms.star_expr}
):
return MATH_PRIORITIES[leaf.type]
if leaf.type in COMPARATORS:
return COMPARATOR_PRIORITY
if (
leaf.type == token.STRING
and previous is not None
and previous.type == token.STRING
):
return STRING_PRIORITY
if leaf.type not in {token.NAME, token.ASYNC}:
return 0
if (
leaf.value == "for"
and leaf.parent
and leaf.parent.type in {syms.comp_for, syms.old_comp_for}
or leaf.type == token.ASYNC
):
if (
not isinstance(leaf.prev_sibling, Leaf)
or leaf.prev_sibling.value != "async"
):
return COMPREHENSION_PRIORITY
if (
leaf.value == "if"
and leaf.parent
and leaf.parent.type in {syms.comp_if, syms.old_comp_if}
):
return COMPREHENSION_PRIORITY
if leaf.value in {"if", "else"} and leaf.parent and leaf.parent.type == syms.test:
return TERNARY_PRIORITY
if leaf.value == "is":
return COMPARATOR_PRIORITY
if (
leaf.value == "in"
and leaf.parent
and leaf.parent.type in {syms.comp_op, syms.comparison}
and not (
previous is not None
and previous.type == token.NAME
and previous.value == "not"
)
):
return COMPARATOR_PRIORITY
if (
leaf.value == "not"
and leaf.parent
and leaf.parent.type == syms.comp_op
and not (
previous is not None
and previous.type == token.NAME
and previous.value == "is"
)
):
return COMPARATOR_PRIORITY
if leaf.value in LOGIC_OPERATORS and leaf.parent:
return LOGIC_PRIORITY
return 0
FMT_OFF = {"# fmt: off", "# fmt:off", "# yapf: disable"}
FMT_ON = {"# fmt: on", "# fmt:on", "# yapf: enable"}
def generate_comments(leaf: LN) -> Iterator[Leaf]:
"""Clean the prefix of the `leaf` and generate comments from it, if any.
Comments in lib2to3 are shoved into the whitespace prefix. This happens
in `pgen2/driver.py:Driver.parse_tokens()`. This was a brilliant implementation
move because it does away with modifying the grammar to include all the
possible places in which comments can be placed.
The sad consequence for us though is that comments don't "belong" anywhere.
This is why this function generates simple parentless Leaf objects for
comments. We simply don't know what the correct parent should be.
No matter though, we can live without this. We really only need to
differentiate between inline and standalone comments. The latter don't
share the line with any code.
Inline comments are emitted as regular token.COMMENT leaves. Standalone
are emitted with a fake STANDALONE_COMMENT token identifier.
"""
for pc in list_comments(leaf.prefix, is_endmarker=leaf.type == token.ENDMARKER):
yield Leaf(pc.type, pc.value, prefix="\n" * pc.newlines)
@dataclass
class ProtoComment:
"""Describes a piece of syntax that is a comment.
It's not a :class:`blib2to3.pytree.Leaf` so that:
* it can be cached (`Leaf` objects should not be reused more than once as
they store their lineno, column, prefix, and parent information);
* `newlines` and `consumed` fields are kept separate from the `value`. This
simplifies handling of special marker comments like ``# fmt: off/on``.
"""
type: int # token.COMMENT or STANDALONE_COMMENT
value: str # content of the comment
newlines: int # how many newlines before the comment
consumed: int # how many characters of the original leaf's prefix did we consume
@lru_cache(maxsize=4096)
def list_comments(prefix: str, *, is_endmarker: bool) -> List[ProtoComment]:
"""Return a list of :class:`ProtoComment` objects parsed from the given `prefix`."""
result: List[ProtoComment] = []
if not prefix or "#" not in prefix:
return result
consumed = 0
nlines = 0
ignored_lines = 0
for index, line in enumerate(prefix.split("\n")):
consumed += len(line) + 1 # adding the length of the split '\n'
line = line.lstrip()
if not line:
nlines += 1
if not line.startswith("#"):
# Escaped newlines outside of a comment are not really newlines at
# all. We treat a single-line comment following an escaped newline
# as a simple trailing comment.
if line.endswith("\\"):
ignored_lines += 1
continue
if index == ignored_lines and not is_endmarker:
comment_type = token.COMMENT # simple trailing comment
else:
comment_type = STANDALONE_COMMENT
comment = make_comment(line)
result.append(
ProtoComment(
type=comment_type, value=comment, newlines=nlines, consumed=consumed
)
)
nlines = 0
return result
def make_comment(content: str) -> str:
"""Return a consistently formatted comment from the given `content` string.
All comments (except for "##", "#!", "#:", '#'", "#%%") should have a single
space between the hash sign and the content.
If `content` didn't start with a hash sign, one is provided.
"""
content = content.rstrip()
if not content:
return "#"
if content[0] == "#":
content = content[1:]
if content and content[0] not in " !:#'%":
content = " " + content
return "#" + content
def split_line(
line: Line,
line_length: int,
inner: bool = False,
features: Collection[Feature] = (),
) -> Iterator[Line]:
"""Split a `line` into potentially 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.
"""
if line.is_comment:
yield line
return
line_str = str(line).strip("\n")
if (
not line.contains_uncollapsable_type_comments()
and not line.should_explode
and not line.is_collection_with_optional_trailing_comma
and (
is_line_short_enough(line, line_length=line_length, line_str=line_str)
or line.contains_unsplittable_type_ignore()
)
):
yield line
return
split_funcs: List[SplitFunc]
if line.is_def:
split_funcs = [left_hand_split]
else:
def rhs(line: Line, features: Collection[Feature]) -> Iterator[Line]:
for omit in generate_trailers_to_omit(line, line_length):
lines = list(right_hand_split(line, line_length, features, omit=omit))
if is_line_short_enough(lines[0], line_length=line_length):
yield from lines
return
# All splits failed, best effort split with no omits.
# This mostly happens to multiline strings that are by definition
# reported as not fitting a single line.
yield from right_hand_split(line, line_length, features=features)
if line.inside_brackets:
split_funcs = [delimiter_split, standalone_comment_split, rhs]
else:
split_funcs = [rhs]
for split_func in split_funcs:
# 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):
if str(l).strip("\n") == line_str:
raise CannotSplit("Split function returned an unchanged result")
result.extend(
split_line(
l, line_length=line_length, inner=True, features=features
)
)
except CannotSplit:
continue
else:
yield from result
break
else:
yield line
def left_hand_split(line: Line, features: Collection[Feature] = ()) -> Iterator[Line]:
"""Split line into many lines, starting with the first matching bracket pair.
Note: this usually looks weird, only use this for function definitions.
Prefer RHS otherwise. This is why this function is not symmetrical with
:func:`right_hand_split` which also handles optional parentheses.
"""
tail_leaves: List[Leaf] = []
body_leaves: List[Leaf] = []
head_leaves: List[Leaf] = []
current_leaves = head_leaves
matching_bracket = None
for leaf in line.leaves:
if (
current_leaves is body_leaves
and leaf.type in CLOSING_BRACKETS
and leaf.opening_bracket is matching_bracket
):
current_leaves = tail_leaves if body_leaves else head_leaves
current_leaves.append(leaf)
if current_leaves is head_leaves:
if leaf.type in OPENING_BRACKETS:
matching_bracket = leaf
current_leaves = body_leaves
if not matching_bracket:
raise CannotSplit("No brackets found")
head = bracket_split_build_line(head_leaves, line, matching_bracket)
body = bracket_split_build_line(body_leaves, line, matching_bracket, is_body=True)
tail = bracket_split_build_line(tail_leaves, line, matching_bracket)
bracket_split_succeeded_or_raise(head, body, tail)
for result in (head, body, tail):
if result:
yield result
def right_hand_split(
line: Line,
line_length: int,
features: Collection[Feature] = (),
omit: Collection[LeafID] = (),
) -> Iterator[Line]:
"""Split line into many lines, starting with the last matching bracket pair.
If the split was by optional parentheses, attempt splitting without them, too.
`omit` is a collection of closing bracket IDs that shouldn't be considered for
this split.
Note: running this function modifies `bracket_depth` on the leaves of `line`.
"""
tail_leaves: List[Leaf] = []
body_leaves: List[Leaf] = []
head_leaves: List[Leaf] = []
current_leaves = tail_leaves
opening_bracket = None
closing_bracket = None
for leaf in reversed(line.leaves):
if current_leaves is body_leaves:
if leaf is opening_bracket:
current_leaves = head_leaves if body_leaves else tail_leaves
current_leaves.append(leaf)
if current_leaves is tail_leaves:
if leaf.type in CLOSING_BRACKETS and id(leaf) not in omit:
opening_bracket = leaf.opening_bracket
closing_bracket = leaf
current_leaves = body_leaves
if not (opening_bracket and closing_bracket and head_leaves):
# If there is no opening or closing_bracket that means the split failed and
# all content is in the tail. Otherwise, if `head_leaves` are empty, it means
# the matching `opening_bracket` wasn't available on `line` anymore.
raise CannotSplit("No brackets found")
tail_leaves.reverse()
body_leaves.reverse()
head_leaves.reverse()
head = bracket_split_build_line(head_leaves, line, opening_bracket)
body = bracket_split_build_line(body_leaves, line, opening_bracket, is_body=True)
tail = bracket_split_build_line(tail_leaves, line, opening_bracket)
bracket_split_succeeded_or_raise(head, body, tail)
if (
# the body shouldn't be exploded
not body.should_explode
# the opening bracket is an optional paren
and opening_bracket.type == token.LPAR
and not opening_bracket.value
# the closing bracket is an optional paren
and closing_bracket.type == token.RPAR
and not closing_bracket.value
# it's not an import (optional parens are the only thing we can split on
# in this case; attempting a split without them is a waste of time)
and not line.is_import
# there are no standalone comments in the body
and not body.contains_standalone_comments(0)
# and we can actually remove the parens
and can_omit_invisible_parens(body, line_length)
):
omit = {id(closing_bracket), *omit}
try:
yield from right_hand_split(line, line_length, features=features, omit=omit)
return
except CannotSplit:
if not (
can_be_split(body)
or is_line_short_enough(body, line_length=line_length)
):
raise CannotSplit(
"Splitting failed, body is still too long and can't be split."
)
elif head.contains_multiline_strings() or tail.contains_multiline_strings():
raise CannotSplit(
"The current optional pair of parentheses is bound to fail to "
"satisfy the splitting algorithm because the head or the tail "
"contains multiline strings which by definition never fit one "
"line."
)
ensure_visible(opening_bracket)
ensure_visible(closing_bracket)
for result in (head, body, tail):
if result:
yield result
def bracket_split_succeeded_or_raise(head: Line, body: Line, tail: Line) -> None:
"""Raise :exc:`CannotSplit` if the last left- or right-hand split failed.
Do nothing otherwise.
A left- or right-hand split is based on a pair of brackets. Content before
(and including) the opening bracket is left on one line, content inside the
brackets is put on a separate line, and finally content starting with and
following the closing bracket is put on a separate line.
Those are called `head`, `body`, and `tail`, respectively. If the split
produced the same line (all content in `head`) or ended up with an empty `body`
and the `tail` is just the closing bracket, then it's considered failed.
"""
tail_len = len(str(tail).strip())
if not body:
if tail_len == 0:
raise CannotSplit("Splitting brackets produced the same line")
elif tail_len < 3:
raise CannotSplit(
f"Splitting brackets on an empty body to save "
f"{tail_len} characters is not worth it"
)
def bracket_split_build_line(
leaves: List[Leaf], original: Line, opening_bracket: Leaf, *, is_body: bool = False
) -> Line:
"""Return a new line with given `leaves` and respective comments from `original`.
If `is_body` is True, the result line is one-indented inside brackets and as such
has its first leaf's prefix normalized and a trailing comma added when expected.
"""
result = Line(depth=original.depth)
if is_body:
result.inside_brackets = True
result.depth += 1
if leaves:
# Since body is a new indent level, remove spurious leading whitespace.
normalize_prefix(leaves[0], inside_brackets=True)
# Ensure a trailing comma for imports and standalone function arguments, but
# be careful not to add one after any comments.
no_commas = original.is_def 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:
leaves.insert(i + 1, Leaf(token.COMMA, ","))
break
# Populate the line
for leaf in leaves:
result.append(leaf, preformatted=True)
for comment_after in original.comments_after(leaf):
result.append(comment_after, preformatted=True)
if is_body:
result.should_explode = should_explode(result, opening_bracket)
return result
def dont_increase_indentation(split_func: SplitFunc) -> SplitFunc:
"""Normalize prefix of the first leaf in every line returned by `split_func`.
This is a decorator over relevant split functions.
"""
@wraps(split_func)
def split_wrapper(line: Line, features: Collection[Feature] = ()) -> Iterator[Line]:
for l in split_func(line, features):
normalize_prefix(l.leaves[0], inside_brackets=True)
yield l
return split_wrapper
@dont_increase_indentation
def delimiter_split(line: Line, features: Collection[Feature] = ()) -> Iterator[Line]:
"""Split according to delimiters of the highest priority.
If the appropriate Features are given, the split will add trailing commas
also in function signatures and calls that contain `*` and `**`.
"""
try:
last_leaf = line.leaves[-1]
except IndexError:
raise CannotSplit("Line empty")
bt = line.bracket_tracker
try:
delimiter_priority = bt.max_delimiter_priority(exclude={id(last_leaf)})
except ValueError:
raise CannotSplit("No delimiters found")
if delimiter_priority == DOT_PRIORITY:
if bt.delimiter_count_with_priority(delimiter_priority) == 1:
raise CannotSplit("Splitting a single attribute from its owner looks wrong")
current_line = Line(depth=line.depth, inside_brackets=line.inside_brackets)
lowest_depth = sys.maxsize
trailing_comma_safe = True
def append_to_line(leaf: Leaf) -> Iterator[Line]:
"""Append `leaf` to current line or to new line if appending impossible."""
nonlocal current_line
try:
current_line.append_safe(leaf, preformatted=True)
except ValueError:
yield current_line
current_line = Line(depth=line.depth, inside_brackets=line.inside_brackets)
current_line.append(leaf)
for leaf in line.leaves:
yield from append_to_line(leaf)
for comment_after in line.comments_after(leaf):
yield from append_to_line(comment_after)
lowest_depth = min(lowest_depth, leaf.bracket_depth)
if leaf.bracket_depth == lowest_depth:
if is_vararg(leaf, within={syms.typedargslist}):
trailing_comma_safe = (
trailing_comma_safe and Feature.TRAILING_COMMA_IN_DEF in features
)
elif is_vararg(leaf, within={syms.arglist, syms.argument}):
trailing_comma_safe = (
trailing_comma_safe and Feature.TRAILING_COMMA_IN_CALL in features
)
leaf_priority = bt.delimiters.get(id(leaf))
if leaf_priority == delimiter_priority:
yield current_line
current_line = Line(depth=line.depth, inside_brackets=line.inside_brackets)
if current_line:
if (
trailing_comma_safe
and delimiter_priority == COMMA_PRIORITY
and current_line.leaves[-1].type != token.COMMA
and current_line.leaves[-1].type != STANDALONE_COMMENT
):
current_line.append(Leaf(token.COMMA, ","))
yield current_line
@dont_increase_indentation
def standalone_comment_split(
line: Line, features: Collection[Feature] = ()
) -> Iterator[Line]:
"""Split standalone comments from the rest of the line."""
if not line.contains_standalone_comments(0):
raise CannotSplit("Line does not have any standalone comments")
current_line = Line(depth=line.depth, inside_brackets=line.inside_brackets)
def append_to_line(leaf: Leaf) -> Iterator[Line]:
"""Append `leaf` to current line or to new line if appending impossible."""
nonlocal current_line
try:
current_line.append_safe(leaf, preformatted=True)
except ValueError:
yield current_line
current_line = Line(depth=line.depth, inside_brackets=line.inside_brackets)
current_line.append(leaf)
for leaf in line.leaves:
yield from append_to_line(leaf)
for comment_after in line.comments_after(leaf):
yield from append_to_line(comment_after)
if current_line:
yield current_line
def is_import(leaf: Leaf) -> bool:
"""Return True if the given leaf starts an import statement."""
p = leaf.parent
t = leaf.type
v = leaf.value
return bool(
t == token.NAME
and (
(v == "import" and p and p.type == syms.import_name)
or (v == "from" and p and p.type == syms.import_from)
)
)
def is_type_comment(leaf: Leaf, suffix: str = "") -> bool:
"""Return True if the given leaf is a special comment.
Only returns true for type comments for now."""
t = leaf.type
v = leaf.value
return t in {token.COMMENT, t == STANDALONE_COMMENT} and v.startswith(
"# type:" + suffix
)
def normalize_prefix(leaf: Leaf, *, inside_brackets: bool) -> None:
"""Leave existing extra newlines if not `inside_brackets`. Remove everything
else.
Note: don't use backslashes for formatting or you'll lose your voting rights.
"""
if not inside_brackets:
spl = leaf.prefix.split("#")
if "\\" not in spl[0]:
nl_count = spl[-1].count("\n")
if len(spl) > 1:
nl_count -= 1
leaf.prefix = "\n" * nl_count
return
leaf.prefix = ""
def normalize_string_prefix(leaf: Leaf, remove_u_prefix: bool = False) -> None:
"""Make all string prefixes lowercase.
If remove_u_prefix is given, also removes any u prefix from the string.
Note: Mutates its argument.
"""
match = re.match(r"^([furbFURB]*)(.*)$", 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()
if remove_u_prefix:
new_prefix = new_prefix.replace("u", "")
leaf.value = f"{new_prefix}{match.group(2)}"
def normalize_string_quotes(leaf: Leaf) -> None:
"""Prefer double quotes but only if it doesn't cause more escaping.
Adds or removes backslashes as appropriate. Doesn't parse and fix
strings nested in f-strings (yet).
Note: Mutates its argument.
"""
value = leaf.value.lstrip("furbFURB")
if value[:3] == '"""':
return
elif value[:3] == "'''":
orig_quote = "'''"
new_quote = '"""'
elif value[0] == '"':
orig_quote = '"'
new_quote = "'"
else:
orig_quote = "'"
new_quote = '"'
first_quote_pos = leaf.value.find(orig_quote)
if first_quote_pos == -1:
return # There's an internal error
prefix = leaf.value[:first_quote_pos]
unescaped_new_quote = re.compile(rf"(([^\\]|^)(\\\\)*){new_quote}")
escaped_new_quote = re.compile(rf"([^\\]|^)\\((?:\\\\)*){new_quote}")
escaped_orig_quote = re.compile(rf"([^\\]|^)\\((?:\\\\)*){orig_quote}")
body = leaf.value[first_quote_pos + len(orig_quote) : -len(orig_quote)]
if "r" in prefix.casefold():
if unescaped_new_quote.search(body):
# There's at least one unescaped new_quote in this raw string
# so converting is impossible
return
# Do not introduce or remove backslashes in raw strings
new_body = body
else:
# remove unnecessary escapes
new_body = sub_twice(escaped_new_quote, rf"\1\2{new_quote}", body)
if body != new_body:
# Consider the string without unnecessary escapes as the original
body = new_body
leaf.value = f"{prefix}{orig_quote}{body}{orig_quote}"
new_body = sub_twice(escaped_orig_quote, rf"\1\2{orig_quote}", new_body)
new_body = sub_twice(unescaped_new_quote, rf"\1\\{new_quote}", new_body)
if "f" in prefix.casefold():
matches = re.findall(
r"""
(?:[^{]|^)\{ # start of the string or a non-{ followed by a single {
([^{].*?) # contents of the brackets except if begins with {{
\}(?:[^}]|$) # A } followed by end of the string or a non-}
""",
new_body,
re.VERBOSE,
)
for m in matches:
if "\\" in str(m):
# Do not introduce backslashes in interpolated expressions
return
if new_quote == '"""' and new_body[-1:] == '"':
# edge case:
new_body = new_body[:-1] + '\\"'
orig_escape_count = body.count("\\")
new_escape_count = new_body.count("\\")
if new_escape_count > orig_escape_count:
return # Do not introduce more escaping
if new_escape_count == orig_escape_count and orig_quote == '"':
return # Prefer double quotes
leaf.value = f"{prefix}{new_quote}{new_body}{new_quote}"
def normalize_numeric_literal(leaf: Leaf) -> None:
"""Normalizes numeric (float, int, and complex) literals.
All letters used in the representation are normalized to lowercase (except
in Python 2 long literals).
"""
text = leaf.value.lower()
if text.startswith(("0o", "0b")):
# Leave octal and binary literals alone.
pass
elif text.startswith("0x"):
# Change hex literals to upper case.
before, after = text[:2], text[2:]
text = f"{before}{after.upper()}"
elif "e" in text:
before, after = text.split("e")
sign = ""
if after.startswith("-"):
after = after[1:]
sign = "-"
elif after.startswith("+"):
after = after[1:]
before = format_float_or_int_string(before)
text = f"{before}e{sign}{after}"
elif text.endswith(("j", "l")):
number = text[:-1]
suffix = text[-1]
# Capitalize in "2L" because "l" looks too similar to "1".
if suffix == "l":
suffix = "L"
text = f"{format_float_or_int_string(number)}{suffix}"
else:
text = format_float_or_int_string(text)
leaf.value = text
def format_float_or_int_string(text: str) -> str:
"""Formats a float string like "1.0"."""
if "." not in text:
return text
before, after = text.split(".")
return f"{before or 0}.{after or 0}"
def normalize_invisible_parens(node: Node, parens_after: Set[str]) -> None:
"""Make existing optional parentheses invisible or create new ones.
`parens_after` is a set of string leaf values immediately after which parens
should be put.
Standardizes on visible parentheses for single-element tuples, and keeps
existing visible parentheses for other tuples and generator expressions.
"""
for pc in list_comments(node.prefix, is_endmarker=False):
if pc.value in FMT_OFF:
# This `node` has a prefix with `# fmt: off`, don't mess with parens.
return
check_lpar = False
for index, child in enumerate(list(node.children)):
# Add parentheses around long tuple unpacking in assignments.
if (
index == 0
and isinstance(child, Node)
and child.type == syms.testlist_star_expr
):
check_lpar = True
if check_lpar:
if is_walrus_assignment(child):
continue
if child.type == syms.atom:
# Determines if the underlying atom should be surrounded with
# invisible params - also makes parens invisible recursively
# within the atom and removes repeated invisible parens within
# the atom
should_surround_with_parens = maybe_make_parens_invisible_in_atom(
child, parent=node
)
if should_surround_with_parens:
lpar = Leaf(token.LPAR, "")
rpar = Leaf(token.RPAR, "")
index = child.remove() or 0
node.insert_child(index, Node(syms.atom, [lpar, child, rpar]))
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]))
elif node.type == syms.import_from:
# "import from" nodes store parentheses directly as part of
# the statement
if child.type == token.LPAR:
# make parentheses invisible
child.value = "" # type: ignore
node.children[-1].value = "" # type: ignore
elif child.type != token.STAR:
# insert invisible parentheses
node.insert_child(index, Leaf(token.LPAR, ""))
node.append_child(Leaf(token.RPAR, ""))
break
elif not (isinstance(child, Leaf) and is_multiline_string(child)):
# wrap 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)
check_lpar = isinstance(child, Leaf) and child.value in parens_after
def normalize_fmt_off(node: Node) -> None:
"""Convert content between `# fmt: off`/`# fmt: on` into standalone comments."""
try_again = True
while try_again:
try_again = convert_one_fmt_off_pair(node)
def convert_one_fmt_off_pair(node: Node) -> bool:
"""Convert content of a single `# fmt: off`/`# fmt: on` into a standalone comment.
Returns True if a pair was converted.
"""
for leaf in node.leaves():
previous_consumed = 0
for comment in list_comments(leaf.prefix, is_endmarker=False):
if comment.value in FMT_OFF:
# We only want standalone comments. If there's no previous leaf or
# the previous leaf is indentation, it's a standalone comment in
# disguise.
if comment.type != STANDALONE_COMMENT:
prev = preceding_leaf(leaf)
if prev and prev.type not in WHITESPACE:
continue
ignored_nodes = list(generate_ignored_nodes(leaf))
if not ignored_nodes:
continue
first = ignored_nodes[0] # Can be a container node with the `leaf`.
parent = first.parent
prefix = first.prefix
first.prefix = prefix[comment.consumed :]
hidden_value = (
comment.value + "\n" + "".join(str(n) for n in ignored_nodes)
)
if hidden_value.endswith("\n"):
# That happens when one of the `ignored_nodes` ended with a NEWLINE
# leaf (possibly followed by a DEDENT).
hidden_value = hidden_value[:-1]
first_idx = None
for ignored in ignored_nodes:
index = ignored.remove()
if first_idx is None:
first_idx = index
assert parent is not None, "INTERNAL ERROR: fmt: on/off handling (1)"
assert first_idx is not None, "INTERNAL ERROR: fmt: on/off handling (2)"
parent.insert_child(
first_idx,
Leaf(
STANDALONE_COMMENT,
hidden_value,
prefix=prefix[:previous_consumed] + "\n" * comment.newlines,
),
)
return True
previous_consumed = comment.consumed
return False
def generate_ignored_nodes(leaf: Leaf) -> Iterator[LN]:
"""Starting from the container of `leaf`, generate all leaves until `# fmt: on`.
Stops at the end of the block.
"""
container: Optional[LN] = container_of(leaf)
while container is not None and container.type != token.ENDMARKER:
for comment in list_comments(container.prefix, is_endmarker=False):
if comment.value in FMT_ON:
return
yield container
container = container.next_sibling
def maybe_make_parens_invisible_in_atom(node: LN, parent: LN) -> bool:
"""If it's safe, make the parens in the atom `node` invisible, recursively.
Additionally, remove repeated, adjacent invisible parens from the atom `node`
as they are redundant.
Returns whether the node should itself be wrapped in invisible parentheses.
"""
if (
node.type != syms.atom
or is_empty_tuple(node)
or is_one_tuple(node)
or (is_yield(node) and parent.type != syms.expr_stmt)
or max_delimiter_priority_in_atom(node) >= COMMA_PRIORITY
):
return False
first = node.children[0]
last = node.children[-1]
if first.type == token.LPAR and last.type == token.RPAR:
middle = node.children[1]
# make parentheses invisible
first.value = "" # type: ignore
last.value = "" # type: ignore
maybe_make_parens_invisible_in_atom(middle, parent=parent)
if is_atom_with_invisible_parens(middle):
# Strip the invisible parens from `middle` by replacing
# it with the child in-between the invisible parens
middle.replace(middle.children[1])
return False
return True
def is_atom_with_invisible_parens(node: LN) -> bool:
"""Given a `LN`, determines whether it's an atom `node` with invisible
parens. Useful in dedupe-ing and normalizing parens.
"""
if isinstance(node, Leaf) or node.type != syms.atom:
return False
first, last = node.children[0], node.children[-1]
return (
isinstance(first, Leaf)
and first.type == token.LPAR
and first.value == ""
and isinstance(last, Leaf)
and last.type == token.RPAR
and last.value == ""
)
def is_empty_tuple(node: LN) -> bool:
"""Return True if `node` holds an empty tuple."""
return (
node.type == syms.atom
and len(node.children) == 2
and node.children[0].type == token.LPAR
and node.children[1].type == token.RPAR
)
def unwrap_singleton_parenthesis(node: LN) -> Optional[LN]:
"""Returns `wrapped` if `node` is of the shape ( wrapped ).
Parenthesis can be optional. Returns None otherwise"""
if len(node.children) != 3:
return None
lpar, wrapped, rpar = node.children
if not (lpar.type == token.LPAR and rpar.type == token.RPAR):
return None
return wrapped
def is_one_tuple(node: LN) -> bool:
"""Return True if `node` holds a tuple with one element, with or without parens."""
if node.type == syms.atom:
gexp = unwrap_singleton_parenthesis(node)
if gexp is None or gexp.type != syms.testlist_gexp:
return False
return len(gexp.children) == 2 and gexp.children[1].type == token.COMMA
return (
node.type in IMPLICIT_TUPLE
and len(node.children) == 2
and node.children[1].type == token.COMMA
)
def is_walrus_assignment(node: LN) -> bool:
"""Return True iff `node` is of the shape ( test := test )"""
inner = unwrap_singleton_parenthesis(node)
return inner is not None and inner.type == syms.namedexpr_test
def is_yield(node: LN) -> bool:
"""Return True if `node` holds a `yield` or `yield from` expression."""
if node.type == syms.yield_expr:
return True
if node.type == token.NAME and node.value == "yield": # type: ignore
return True
if node.type != syms.atom:
return False
if len(node.children) != 3:
return False
lpar, expr, rpar = node.children
if lpar.type == token.LPAR and rpar.type == token.RPAR:
return is_yield(expr)
return False
def is_vararg(leaf: Leaf, within: Set[NodeType]) -> bool:
"""Return True if `leaf` is a star or double star in a vararg or kwarg.
If `within` includes VARARGS_PARENTS, this applies to function signatures.
If `within` includes UNPACKING_PARENTS, it applies to right hand-side
extended iterable unpacking (PEP 3132) and additional unpacking
generalizations (PEP 448).
"""
if leaf.type not in VARARGS_SPECIALS or not leaf.parent:
return False
p = leaf.parent
if p.type == syms.star_expr:
# Star expressions are also used as assignment targets in extended
# iterable unpacking (PEP 3132). See what its parent is instead.
if not p.parent:
return False
p = p.parent
return p.type in within
def is_multiline_string(leaf: Leaf) -> bool:
"""Return True if `leaf` is a multiline string that actually spans many lines."""
value = leaf.value.lstrip("furbFURB")
return value[:3] in {'"""', "'''"} and "\n" in value
def is_stub_suite(node: Node) -> bool:
"""Return True if `node` is a suite with a stub body."""
if (
len(node.children) != 4
or node.children[0].type != token.NEWLINE
or node.children[1].type != token.INDENT
or node.children[3].type != token.DEDENT
):
return False
return is_stub_body(node.children[2])
def is_stub_body(node: LN) -> bool:
"""Return True if `node` is a simple statement containing an ellipsis."""
if not isinstance(node, Node) or node.type != syms.simple_stmt:
return False
if len(node.children) != 2:
return False
child = node.children[0]
return (
child.type == syms.atom
and len(child.children) == 3
and all(leaf == Leaf(token.DOT, ".") for leaf in child.children)
)
def max_delimiter_priority_in_atom(node: LN) -> Priority:
"""Return maximum delimiter priority inside `node`.
This is specific to atoms with contents contained in a pair of parentheses.
If `node` isn't an atom or there are no enclosing parentheses, returns 0.
"""
if node.type != syms.atom:
return 0
first = node.children[0]
last = node.children[-1]
if not (first.type == token.LPAR and last.type == token.RPAR):
return 0
bt = BracketTracker()
for c in node.children[1:-1]:
if isinstance(c, Leaf):
bt.mark(c)
else:
for leaf in c.leaves():
bt.mark(leaf)
try:
return bt.max_delimiter_priority()
except ValueError:
return 0
def ensure_visible(leaf: Leaf) -> None:
"""Make sure parentheses are visible.
They could be invisible as part of some statements (see
:func:`normalize_invisible_parens` and :func:`visit_import_from`).
"""
if leaf.type == token.LPAR:
leaf.value = "("
elif leaf.type == token.RPAR:
leaf.value = ")"
def should_explode(line: Line, opening_bracket: Leaf) -> bool:
"""Should `line` immediately be split with `delimiter_split()` after RHS?"""
if not (
opening_bracket.parent
and opening_bracket.parent.type in {syms.atom, syms.import_from}
and opening_bracket.value in "[{("
):
return False
try:
last_leaf = line.leaves[-1]
exclude = {id(last_leaf)} if last_leaf.type == token.COMMA else set()
max_priority = line.bracket_tracker.max_delimiter_priority(exclude=exclude)
except (IndexError, ValueError):
return False
return max_priority == COMMA_PRIORITY
def get_features_used(node: Node) -> Set[Feature]:
"""Return a set of (relatively) new Python features used in this file.
Currently looking for:
- f-strings;
- underscores in numeric literals;
- trailing commas after * or ** in function signatures and calls;
- positional only arguments in function signatures and lambdas;
"""
features: Set[Feature] = set()
for n in node.pre_order():
if n.type == token.STRING:
value_head = n.value[:2] # type: ignore
if value_head in {'f"', 'F"', "f'", "F'", "rf", "fr", "RF", "FR"}:
features.add(Feature.F_STRINGS)
elif n.type == token.NUMBER:
if "_" in n.value: # type: ignore
features.add(Feature.NUMERIC_UNDERSCORES)
elif n.type == token.SLASH:
if n.parent and n.parent.type in {syms.typedargslist, syms.arglist}:
features.add(Feature.POS_ONLY_ARGUMENTS)
elif n.type == token.COLONEQUAL:
features.add(Feature.ASSIGNMENT_EXPRESSIONS)
elif (
n.type in {syms.typedargslist, syms.arglist}
and n.children
and n.children[-1].type == token.COMMA
):
if n.type == syms.typedargslist:
feature = Feature.TRAILING_COMMA_IN_DEF
else:
feature = Feature.TRAILING_COMMA_IN_CALL
for ch in n.children:
if ch.type in STARS:
features.add(feature)
if ch.type == syms.argument:
for argch in ch.children:
if argch.type in STARS:
features.add(feature)
return features
def detect_target_versions(node: Node) -> Set[TargetVersion]:
"""Detect the version to target based on the nodes used."""
features = get_features_used(node)
return {
version for version in TargetVersion if features <= VERSION_TO_FEATURES[version]
}
def generate_trailers_to_omit(line: Line, line_length: int) -> Iterator[Set[LeafID]]:
"""Generate sets of closing bracket IDs that should be omitted in a RHS.
Brackets can be omitted if the entire trailer up to and including
a preceding closing bracket fits in one line.
Yielded sets are cumulative (contain results of previous yields, too). First
set is empty.
"""
omit: Set[LeafID] = set()
yield omit
length = 4 * line.depth
opening_bracket = None
closing_bracket = None
inner_brackets: Set[LeafID] = set()
for index, leaf, leaf_length in enumerate_with_length(line, reversed=True):
length += leaf_length
if length > line_length:
break
has_inline_comment = leaf_length > len(leaf.value) + len(leaf.prefix)
if leaf.type == STANDALONE_COMMENT or has_inline_comment:
break
if opening_bracket:
if leaf is opening_bracket:
opening_bracket = None
elif leaf.type in CLOSING_BRACKETS:
inner_brackets.add(id(leaf))
elif leaf.type in CLOSING_BRACKETS:
if index > 0 and line.leaves[index - 1].type in OPENING_BRACKETS:
# Empty brackets would fail a split so treat them as "inner"
# brackets (e.g. only add them to the `omit` set if another
# pair of brackets was good enough.
inner_brackets.add(id(leaf))
continue
if closing_bracket:
omit.add(id(closing_bracket))
omit.update(inner_brackets)
inner_brackets.clear()
yield omit
if leaf.value:
opening_bracket = leaf.opening_bracket
closing_bracket = leaf
def get_future_imports(node: Node) -> Set[str]:
"""Return a set of __future__ imports in the file."""
imports: Set[str] = set()
def get_imports_from_children(children: List[LN]) -> Generator[str, None, None]:
for child in children:
if isinstance(child, Leaf):
if child.type == token.NAME:
yield child.value
elif child.type == syms.import_as_name:
orig_name = child.children[0]
assert isinstance(orig_name, Leaf), "Invalid syntax parsing imports"
assert orig_name.type == token.NAME, "Invalid syntax parsing imports"
yield orig_name.value
elif child.type == syms.import_as_names:
yield from get_imports_from_children(child.children)
else:
raise AssertionError("Invalid syntax parsing imports")
for child in node.children:
if child.type != syms.simple_stmt:
break
first_child = child.children[0]
if isinstance(first_child, Leaf):
# Continue looking if we see a docstring; otherwise stop.
if (
len(child.children) == 2
and first_child.type == token.STRING
and child.children[1].type == token.NEWLINE
):
continue
else:
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,
root: Path,
include: Pattern[str],
exclude: Pattern[str],
report: "Report",
) -> Iterator[Path]:
"""Generate all files under `path` whose paths are not excluded by the
`exclude` regex, but are included by the `include` regex.
Symbolic links pointing outside of the `root` directory are ignored.
`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():
try:
normalized_path = "/" + child.resolve().relative_to(root).as_posix()
except ValueError:
if child.is_symlink():
report.path_ignored(
child, f"is a symbolic link that points outside {root}"
)
continue
raise
if child.is_dir():
normalized_path += "/"
exclude_match = exclude.search(normalized_path)
if exclude_match and exclude_match.group(0):
report.path_ignored(child, f"matches the --exclude regular expression")
continue
if child.is_dir():
yield from gen_python_files_in_dir(child, root, include, exclude, report)
elif child.is_file():
include_match = include.search(normalized_path)
if include_match:
yield child
@lru_cache()
def find_project_root(srcs: Iterable[str]) -> Path:
"""Return a directory containing .git, .hg, or pyproject.toml.
That directory can be one of the directories passed in `srcs` or their
common parent.
If no directory in the tree contains a marker that would specify it's the
project root, the root of the file system is returned.
"""
if not srcs:
return Path("/").resolve()
common_base = min(Path(src).resolve() for src in srcs)
if common_base.is_dir():
# Append a fake file so `parents` below returns `common_base_dir`, too.
common_base /= "fake-file"
for directory in common_base.parents:
if (directory / ".git").is_dir():
return directory
if (directory / ".hg").is_dir():
return directory
if (directory / "pyproject.toml").is_file():
return directory
return directory
@dataclass
class Report:
"""Provides a reformatting counter. Can be rendered with `str(report)`."""
check: bool = False
quiet: bool = False
verbose: bool = False
change_count: int = 0
same_count: int = 0
failure_count: int = 0
def done(self, src: Path, changed: Changed) -> None:
"""Increment the counter for successful reformatting. Write out a message."""
if changed is Changed.YES:
reformatted = "would reformat" if self.check else "reformatted"
if self.verbose or not self.quiet:
out(f"{reformatted} {src}")
self.change_count += 1
else:
if self.verbose:
if changed is Changed.NO:
msg = f"{src} already well formatted, good job."
else:
msg = f"{src} wasn't modified on disk since last run."
out(msg, bold=False)
self.same_count += 1
def failed(self, src: Path, message: str) -> None:
"""Increment the counter for failed reformatting. Write out a message."""
err(f"error: cannot format {src}: {message}")
self.failure_count += 1
def path_ignored(self, path: Path, message: str) -> None:
if self.verbose:
out(f"{path} ignored: {message}", bold=False)
@property
def return_code(self) -> int:
"""Return the exit code that the app should use.
This considers the current state of changed files and failures:
- if there were any failures, return 123;
- if any files were changed and --check is being used, return 1;
- otherwise return 0.
"""
# According to http://tldp.org/LDP/abs/html/exitcodes.html starting with
# 126 we have special return codes reserved by the shell.
if self.failure_count:
return 123
elif self.change_count and self.check:
return 1
return 0
def __str__(self) -> str:
"""Render a color report of the current state.
Use `click.unstyle` to remove colors.
"""
if self.check:
reformatted = "would be reformatted"
unchanged = "would be left unchanged"
failed = "would fail to reformat"
else:
reformatted = "reformatted"
unchanged = "left unchanged"
failed = "failed to reformat"
report = []
if self.change_count:
s = "s" if self.change_count > 1 else ""
report.append(
click.style(f"{self.change_count} file{s} {reformatted}", bold=True)
)
if self.same_count:
s = "s" if self.same_count > 1 else ""
report.append(f"{self.same_count} file{s} {unchanged}")
if self.failure_count:
s = "s" if self.failure_count > 1 else ""
report.append(
click.style(f"{self.failure_count} file{s} {failed}", fg="red")
)
return ", ".join(report) + "."
def parse_ast(src: str) -> Union[ast.AST, ast3.AST, ast27.AST]:
filename = "<unknown>"
if sys.version_info >= (3, 8):
# TODO: support Python 4+ ;)
for minor_version in range(sys.version_info[1], 4, -1):
try:
return ast.parse(src, filename, feature_version=(3, minor_version))
except SyntaxError:
continue
else:
for feature_version in (7, 6):
try:
return ast3.parse(src, filename, feature_version=feature_version)
except SyntaxError:
continue
return ast27.parse(src)
def _fixup_ast_constants(
node: Union[ast.AST, ast3.AST, ast27.AST]
) -> Union[ast.AST, ast3.AST, ast27.AST]:
"""Map ast nodes deprecated in 3.8 to Constant."""
# casts are required until this is released:
# https://github.com/python/typeshed/pull/3142
if isinstance(node, (ast.Str, ast3.Str, ast27.Str, ast.Bytes, ast3.Bytes)):
return cast(ast.AST, ast.Constant(value=node.s))
elif isinstance(node, (ast.Num, ast3.Num, ast27.Num)):
return cast(ast.AST, ast.Constant(value=node.n))
elif isinstance(node, (ast.NameConstant, ast3.NameConstant)):
return cast(ast.AST, ast.Constant(value=node.value))
return node
def assert_equivalent(src: str, dst: str) -> None:
"""Raise AssertionError if `src` and `dst` aren't equivalent."""
def _v(node: Union[ast.AST, ast3.AST, ast27.AST], depth: int = 0) -> Iterator[str]:
"""Simple visitor generating strings to compare ASTs by content."""
node = _fixup_ast_constants(node)
yield f"{' ' * depth}{node.__class__.__name__}("
for field in sorted(node._fields):
# TypeIgnore has only one field 'lineno' which breaks this comparison
type_ignore_classes = (ast3.TypeIgnore, ast27.TypeIgnore)
if sys.version_info >= (3, 8):
type_ignore_classes += (ast.TypeIgnore,)
if isinstance(node, type_ignore_classes):
break
try:
value = getattr(node, field)
except AttributeError:
continue
yield f"{' ' * (depth+1)}{field}="
if isinstance(value, list):
for item in value:
# Ignore nested tuples within del statements, because we may insert
# parentheses and they change the AST.
if (
field == "targets"
and isinstance(node, (ast.Delete, ast3.Delete, ast27.Delete))
and isinstance(item, (ast.Tuple, ast3.Tuple, ast27.Tuple))
):
for item in item.elts:
yield from _v(item, depth + 2)
elif isinstance(item, (ast.AST, ast3.AST, ast27.AST)):
yield from _v(item, depth + 2)
elif isinstance(value, (ast.AST, ast3.AST, ast27.AST)):
yield from _v(value, depth + 2)
else:
yield f"{' ' * (depth+2)}{value!r}, # {value.__class__.__name__}"
yield f"{' ' * depth}) # /{node.__class__.__name__}"
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}"
)
try:
dst_ast = parse_ast(dst)
except Exception as exc:
log = dump_to_file("".join(traceback.format_tb(exc.__traceback__)), dst)
raise AssertionError(
f"INTERNAL ERROR: Black produced invalid code: {exc}. "
f"Please report a bug on https://github.com/psf/black/issues. "
f"This invalid output might be helpful: {log}"
) from None
src_ast_str = "\n".join(_v(src_ast))
dst_ast_str = "\n".join(_v(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/psf/black/issues. "
f"This diff might be helpful: {log}"
) from None
def assert_stable(src: str, dst: str, mode: FileMode) -> None:
"""Raise AssertionError if `dst` reformats differently the second time."""
newdst = format_str(dst, mode=mode)
if dst != newdst:
log = dump_to_file(
diff(src, dst, "source", "first pass"),
diff(dst, newdst, "first pass", "second pass"),
)
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/psf/black/issues. "
f"This diff might be helpful: {log}"
) from None
def dump_to_file(*output: str) -> str:
"""Dump `output` to a temporary file. Return path to the file."""
with tempfile.NamedTemporaryFile(
mode="w", prefix="blk_", suffix=".log", delete=False, encoding="utf8"
) as f:
for lines in output:
f.write(lines)
if lines and lines[-1] != "\n":
f.write("\n")
return f.name
@contextmanager
def nullcontext() -> Iterator[None]:
"""Return context manager that does nothing.
Similar to `nullcontext` from 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")]
return "".join(
difflib.unified_diff(a_lines, b_lines, fromfile=a_name, tofile=b_name, n=5)
)
def cancel(tasks: Iterable[asyncio.Task]) -> None:
"""asyncio signal handler that cancels all `tasks` and reports to stderr."""
err("Aborted!")
for task in tasks:
task.cancel()
def shutdown(loop: asyncio.AbstractEventLoop) -> None:
"""Cancel all pending tasks on `loop`, wait for them, and close the loop."""
try:
if sys.version_info[:2] >= (3, 7):
all_tasks = asyncio.all_tasks
else:
all_tasks = asyncio.Task.all_tasks
# This part is borrowed from asyncio/runners.py in Python 3.7b2.
to_cancel = [task for task in all_tasks(loop) if not task.done()]
if not to_cancel:
return
for task in to_cancel:
task.cancel()
loop.run_until_complete(
asyncio.gather(*to_cancel, loop=loop, return_exceptions=True)
)
finally:
# `concurrent.futures.Future` objects cannot be cancelled once they
# are already running. There might be some when the `shutdown()` happened.
# Silence their logger's spew about the event loop being closed.
cf_logger = logging.getLogger("concurrent.futures")
cf_logger.setLevel(logging.CRITICAL)
loop.close()
def sub_twice(regex: Pattern[str], replacement: str, original: str) -> str:
"""Replace `regex` with `replacement` twice on `original`.
This is used by string normalization to perform replaces on
overlapping matches.
"""
return regex.sub(replacement, regex.sub(replacement, original))
def re_compile_maybe_verbose(regex: str) -> Pattern[str]:
"""Compile a regular expression string in `regex`.
If it contains newlines, use verbose mode.
"""
if "\n" in regex:
regex = "(?x)" + regex
return re.compile(regex)
def enumerate_reversed(sequence: Sequence[T]) -> Iterator[Tuple[Index, T]]:
"""Like `reversed(enumerate(sequence))` if that were possible."""
index = len(sequence) - 1
for element in reversed(sequence):
yield (index, element)
index -= 1
def enumerate_with_length(
line: Line, reversed: bool = False
) -> Iterator[Tuple[Index, Leaf, int]]:
"""Return an enumeration of leaves with their length.
Stops prematurely on multiline strings and standalone comments.
"""
op = cast(
Callable[[Sequence[Leaf]], Iterator[Tuple[Index, Leaf]]],
enumerate_reversed if reversed else enumerate,
)
for index, leaf in op(line.leaves):
length = len(leaf.prefix) + len(leaf.value)
if "\n" in leaf.value:
return # Multiline strings, we can't continue.
for comment in line.comments_after(leaf):
length += len(comment.value)
yield index, leaf, length
def is_line_short_enough(line: Line, *, line_length: int, line_str: str = "") -> bool:
"""Return True if `line` is no longer than `line_length`.
Uses the provided `line_str` rendering, if any, otherwise computes a new one.
"""
if not line_str:
line_str = str(line).strip("\n")
return (
len(line_str) <= line_length
and "\n" not in line_str # multiline strings
and not line.contains_standalone_comments()
)
def can_be_split(line: Line) -> bool:
"""Return False if the line cannot be split *for sure*.
This is not an exhaustive search but a cheap heuristic that we can use to
avoid some unfortunate formattings (mostly around wrapping unsplittable code
in unnecessary parentheses).
"""
leaves = line.leaves
if len(leaves) < 2:
return False
if leaves[0].type == token.STRING and leaves[1].type == token.DOT:
call_count = 0
dot_count = 0
next = leaves[-1]
for leaf in leaves[-2::-1]:
if leaf.type in OPENING_BRACKETS:
if next.type not in CLOSING_BRACKETS:
return False
call_count += 1
elif leaf.type == token.DOT:
dot_count += 1
elif leaf.type == token.NAME:
if not (next.type == token.DOT or next.type in OPENING_BRACKETS):
return False
elif leaf.type not in CLOSING_BRACKETS:
return False
if dot_count > 1 and call_count > 1:
return False
return True
def can_omit_invisible_parens(line: Line, line_length: int) -> bool:
"""Does `line` have a shape safe to reformat without optional parens around it?
Returns True for only a subset of potentially nice looking formattings but
the point is to not return false positives that end up producing lines that
are too long.
"""
bt = line.bracket_tracker
if not bt.delimiters:
# Without delimiters the optional parentheses are useless.
return True
max_priority = bt.max_delimiter_priority()
if bt.delimiter_count_with_priority(max_priority) > 1:
# With more than one delimiter of a kind the optional parentheses read better.
return False
if max_priority == DOT_PRIORITY:
# A single stranded method call doesn't require optional parentheses.
return True
assert len(line.leaves) >= 2, "Stranded delimiter"
first = line.leaves[0]
second = line.leaves[1]
penultimate = line.leaves[-2]
last = line.leaves[-1]
# With a single delimiter, omit if the expression starts or ends with
# a bracket.
if first.type in OPENING_BRACKETS and second.type not in CLOSING_BRACKETS:
remainder = False
length = 4 * line.depth
for _index, leaf, leaf_length in enumerate_with_length(line):
if leaf.type in CLOSING_BRACKETS and leaf.opening_bracket is first:
remainder = True
if remainder:
length += leaf_length
if length > line_length:
break
if leaf.type in OPENING_BRACKETS:
# There are brackets we can further split on.
remainder = False
else:
# checked the entire string and line length wasn't exceeded
if len(line.leaves) == _index + 1:
return True
# Note: we are not returning False here because a line might have *both*
# a leading opening bracket and a trailing closing bracket. If the
# opening bracket doesn't match our rule, maybe the closing will.
if (
last.type == token.RPAR
or last.type == token.RBRACE
or (
# don't use indexing for omitting optional parentheses;
# it looks weird
last.type == token.RSQB
and last.parent
and last.parent.type != syms.trailer
)
):
if penultimate.type in OPENING_BRACKETS:
# Empty brackets don't help.
return False
if is_multiline_string(first):
# Additional wrapping of a multiline string in this situation is
# unnecessary.
return True
length = 4 * line.depth
seen_other_brackets = False
for _index, leaf, leaf_length in enumerate_with_length(line):
length += leaf_length
if leaf is last.opening_bracket:
if seen_other_brackets or length <= line_length:
return True
elif leaf.type in OPENING_BRACKETS:
# There are brackets we can further split on.
seen_other_brackets = True
return False
def get_cache_file(mode: FileMode) -> Path:
return CACHE_DIR / f"cache.{mode.get_cache_key()}.pickle"
def read_cache(mode: FileMode) -> Cache:
"""Read the cache if it exists and is well formed.
If it is not well formed, the call to write_cache later should resolve the issue.
"""
cache_file = get_cache_file(mode)
if not cache_file.exists():
return {}
with cache_file.open("rb") as fobj:
try:
cache: Cache = pickle.load(fobj)
except pickle.UnpicklingError:
return {}
return cache
def get_cache_info(path: Path) -> CacheInfo:
"""Return the information used to check if a file is already formatted or not."""
stat = path.stat()
return stat.st_mtime, stat.st_size
def filter_cached(cache: Cache, sources: Iterable[Path]) -> Tuple[Set[Path], Set[Path]]:
"""Split an iterable of paths in `sources` into two sets.
The first contains paths of files that modified on disk or are not in the
cache. The other contains paths to non-modified files.
"""
todo, done = set(), set()
for src in sources:
src = src.resolve()
if cache.get(src) != get_cache_info(src):
todo.add(src)
else:
done.add(src)
return todo, done
def write_cache(cache: Cache, sources: Iterable[Path], mode: FileMode) -> 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)
os.replace(f.name, cache_file)
except OSError:
pass
def patch_click() -> None:
"""Make Click not crash.
On certain misconfigured environments, Python 3 selects the ASCII encoding as the
default which restricts paths that it can access during the lifetime of the
application. Click refuses to work in this scenario by raising a RuntimeError.
In case of Black the likelihood that non-ASCII characters are going to be used in
file paths is minimal since it's Python source code. Moreover, this crash was
spurious on Python 3.7 thanks to PEP 538 and PEP 540.
"""
try:
from click import core
from click import _unicodefun # type: ignore
except ModuleNotFoundError:
return
for module in (core, _unicodefun):
if hasattr(module, "_verify_python3_env"):
module._verify_python3_env = lambda: None
def patched_main() -> None:
freeze_support()
patch_click()
main()
if __name__ == "__main__":
patched_main()