#!/usr/bin/env python3
+
import asyncio
from asyncio.base_events import BaseEventLoop
from concurrent.futures import Executor, ProcessPoolExecutor
import tokenize
import sys
from typing import (
- Dict, Generic, Iterable, Iterator, List, Optional, Set, Tuple, TypeVar, Union
+ Dict, Generic, Iterable, Iterator, List, Optional, Set, Tuple, Type, TypeVar, Union
)
-from attr import attrib, dataclass, Factory
+from attr import dataclass, Factory
import click
# lib2to3 fork
from blib2to3.pgen2 import driver, token
from blib2to3.pgen2.parse import ParseError
-__version__ = "18.3a2"
+__version__ = "18.3a4"
DEFAULT_LINE_LENGTH = 88
# types
syms = pygram.python_symbols
class NothingChanged(UserWarning):
- """Raised by `format_file` when the reformatted code is the same as source."""
+ """Raised by :func:`format_file` when reformatted code is the same as source."""
class CannotSplit(Exception):
"""A readable split that fits the allotted line length is impossible.
- Raised by `left_hand_split()` and `right_hand_split()`.
+ Raised by :func:`left_hand_split`, :func:`right_hand_split`, and
+ :func:`delimiter_split`.
"""
+class FormatError(Exception):
+ """Base exception for `# fmt: on` and `# fmt: off` handling.
+
+ It holds the number of bytes of the prefix consumed before the format
+ control comment appeared.
+ """
+
+ def __init__(self, consumed: int) -> None:
+ super().__init__(consumed)
+ self.consumed = consumed
+
+ def trim_prefix(self, leaf: Leaf) -> None:
+ leaf.prefix = leaf.prefix[self.consumed:]
+
+ def leaf_from_consumed(self, leaf: Leaf) -> Leaf:
+ """Returns a new Leaf from the consumed part of the prefix."""
+ unformatted_prefix = leaf.prefix[:self.consumed]
+ return Leaf(token.NEWLINE, unformatted_prefix)
+
+
+class FormatOn(FormatError):
+ """Found a comment like `# fmt: on` in the file."""
+
+
+class FormatOff(FormatError):
+ """Found a comment like `# fmt: off` in the file."""
+
+
@click.command()
@click.option(
'-l',
is_flag=True,
help=(
"Don't write back the files, just return the status. Return code 0 "
- "means nothing changed. Return code 1 means some files were "
+ "means nothing would change. Return code 1 means some files would be "
"reformatted. Return code 123 means there was an internal error."
),
)
@click.argument(
'src',
nargs=-1,
- type=click.Path(exists=True, file_okay=True, dir_okay=True, readable=True),
+ type=click.Path(
+ exists=True, file_okay=True, dir_okay=True, readable=True, allow_dash=True
+ ),
)
@click.pass_context
def main(
elif p.is_file():
# if a file was explicitly given, we don't care about its extension
sources.append(p)
+ elif s == '-':
+ sources.append(Path('-'))
else:
err(f'invalid path: {s}')
if len(sources) == 0:
ctx.exit(0)
elif len(sources) == 1:
p = sources[0]
- report = Report()
+ report = Report(check=check)
try:
- changed = format_file_in_place(
- p, line_length=line_length, fast=fast, write_back=not check
- )
+ if not p.is_file() and str(p) == '-':
+ changed = format_stdin_to_stdout(
+ line_length=line_length, fast=fast, write_back=not check
+ )
+ else:
+ changed = format_file_in_place(
+ p, line_length=line_length, fast=fast, write_back=not check
+ )
report.done(p, changed)
except Exception as exc:
report.failed(p, str(exc))
loop: BaseEventLoop,
executor: Executor,
) -> int:
+ """Run formatting of `sources` in parallel using the provided `executor`.
+
+ (Use ProcessPoolExecutors for actual parallelism.)
+
+ `line_length`, `write_back`, and `fast` options are passed to
+ :func:`format_file_in_place`.
+ """
tasks = {
src: loop.run_in_executor(
executor, format_file_in_place, src, line_length, fast, write_back
}
await asyncio.wait(tasks.values())
cancelled = []
- report = Report()
+ report = Report(check=not write_back)
for src, task in tasks.items():
if not task.done():
report.failed(src, 'timed out, cancelling')
def format_file_in_place(
src: Path, line_length: int, fast: bool, write_back: bool = False
) -> bool:
- """Format the file and rewrite if changed. Return True if changed."""
+ """Format file under `src` path. Return True if changed.
+
+ If `write_back` is True, write reformatted code back to stdout.
+ `line_length` and `fast` options are passed to :func:`format_file_contents`.
+ """
+ with tokenize.open(src) as src_buffer:
+ src_contents = src_buffer.read()
try:
- contents, encoding = format_file(src, line_length=line_length, fast=fast)
+ contents = format_file_contents(
+ src_contents, line_length=line_length, fast=fast
+ )
except NothingChanged:
return False
if write_back:
- with open(src, "w", encoding=encoding) as f:
+ with open(src, "w", encoding=src_buffer.encoding) as f:
f.write(contents)
return True
-def format_file(
- src: Path, line_length: int, fast: bool
-) -> Tuple[FileContent, Encoding]:
- """Reformats a file and returns its contents and encoding."""
- with tokenize.open(src) as src_buffer:
- src_contents = src_buffer.read()
+def format_stdin_to_stdout(
+ line_length: int, fast: bool, write_back: bool = False
+) -> bool:
+ """Format file on stdin. Return True if changed.
+
+ If `write_back` is True, write reformatted code back to stdout.
+ `line_length` and `fast` arguments are passed to :func:`format_file_contents`.
+ """
+ contents = sys.stdin.read()
+ try:
+ contents = format_file_contents(contents, line_length=line_length, fast=fast)
+ return True
+
+ except NothingChanged:
+ return False
+
+ finally:
+ if write_back:
+ sys.stdout.write(contents)
+
+
+def format_file_contents(
+ src_contents: str, line_length: int, fast: bool
+) -> 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.
+ `line_length` is passed to :func:`format_str`.
+ """
if src_contents.strip() == '':
- raise NothingChanged(src)
+ raise NothingChanged
dst_contents = format_str(src_contents, line_length=line_length)
if src_contents == dst_contents:
- raise NothingChanged(src)
+ raise NothingChanged
if not fast:
assert_equivalent(src_contents, dst_contents)
assert_stable(src_contents, dst_contents, line_length=line_length)
- return dst_contents, src_buffer.encoding
+ return dst_contents
def format_str(src_contents: str, line_length: int) -> FileContent:
- """Reformats a string and returns new contents."""
+ """Reformat a string and return new contents.
+
+ `line_length` determines how many characters per line are allowed.
+ """
src_node = lib2to3_parse(src_contents)
dst_contents = ""
- comments: List[Line] = []
lines = LineGenerator()
elt = EmptyLineTracker()
py36 = is_python36(src_node)
before, after = elt.maybe_empty_lines(current_line)
for _ in range(before):
dst_contents += str(empty_line)
- if not current_line.is_comment:
- for comment in comments:
- dst_contents += str(comment)
- comments = []
- for line in split_line(current_line, line_length=line_length, py36=py36):
- dst_contents += str(line)
- else:
- comments.append(current_line)
- for comment in comments:
- dst_contents += str(comment)
+ for line in split_line(current_line, line_length=line_length, py36=py36):
+ dst_contents += str(line)
return dst_contents
+GRAMMARS = [
+ pygram.python_grammar_no_print_statement_no_exec_statement,
+ pygram.python_grammar_no_print_statement,
+ pygram.python_grammar_no_exec_statement,
+ pygram.python_grammar,
+]
+
+
def lib2to3_parse(src_txt: str) -> Node:
"""Given a string with source, return the lib2to3 Node."""
grammar = pygram.python_grammar_no_print_statement
- drv = driver.Driver(grammar, pytree.convert)
if src_txt[-1] != '\n':
nl = '\r\n' if '\r\n' in src_txt[:1024] else '\n'
src_txt += nl
- try:
- result = drv.parse_string(src_txt, True)
- except ParseError as pe:
- lineno, column = pe.context[1]
- lines = src_txt.splitlines()
+ for grammar in GRAMMARS:
+ drv = driver.Driver(grammar, pytree.convert)
try:
- faulty_line = lines[lineno - 1]
- except IndexError:
- faulty_line = "<line number missing in source>"
- raise ValueError(f"Cannot parse: {lineno}:{column}: {faulty_line}") from None
+ result = drv.parse_string(src_txt, True)
+ break
+
+ except ParseError as pe:
+ lineno, column = pe.context[1]
+ lines = src_txt.splitlines()
+ try:
+ faulty_line = lines[lineno - 1]
+ except IndexError:
+ faulty_line = "<line number missing in source>"
+ exc = ValueError(f"Cannot parse: {lineno}:{column}: {faulty_line}")
+ else:
+ raise exc from None
if isinstance(result, Leaf):
result = Node(syms.file_input, [result])
class Visitor(Generic[T]):
- """Basic lib2to3 visitor that yields things on visiting."""
+ """Basic lib2to3 visitor that yields things of type `T` on `visit()`."""
def visit(self, node: LN) -> Iterator[T]:
+ """Main method to visit `node` and its children.
+
+ It tries to find a `visit_*()` method for the given `node.type`, like
+ `visit_simple_stmt` for Node objects or `visit_INDENT` for Leaf objects.
+ If no dedicated `visit_*()` method is found, chooses `visit_default()`
+ instead.
+
+ Then yields objects of type `T` from the selected visitor.
+ """
if node.type < 256:
name = token.tok_name[node.type]
else:
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 = attrib(default=0)
+ tree_depth: int = 0
def visit_default(self, node: LN) -> Iterator[T]:
indent = ' ' * (2 * self.tree_depth)
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: str) -> None:
+ """Pretty-print the lib2to3 AST of a given string of `code`.
+
+ Convenience method for debugging.
+ """
+ v: DebugVisitor[None] = DebugVisitor()
+ list(v.visit(lib2to3_parse(code)))
+
KEYWORDS = set(keyword.kwlist)
WHITESPACE = {token.DEDENT, token.INDENT, token.NEWLINE}
token.AMPER,
token.PERCENT,
token.CIRCUMFLEX,
+ token.TILDE,
token.LEFTSHIFT,
token.RIGHTSHIFT,
token.DOUBLESTAR,
@dataclass
class BracketTracker:
- depth: int = attrib(default=0)
- bracket_match: Dict[Tuple[Depth, NodeType], Leaf] = attrib(default=Factory(dict))
- delimiters: Dict[LeafID, Priority] = attrib(default=Factory(dict))
- previous: Optional[Leaf] = attrib(default=None)
+ """Keeps track of brackets on a line."""
+
+ depth: int = 0
+ bracket_match: Dict[Tuple[Depth, NodeType], Leaf] = Factory(dict)
+ delimiters: Dict[LeafID, Priority] = Factory(dict)
+ previous: Optional[Leaf] = None
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
if leaf.type == token.STRING and self.previous.type == token.STRING:
self.delimiters[id(self.previous)] = STRING_PRIORITY
elif (
- leaf.type == token.NAME and
- leaf.value == 'for' and
- leaf.parent and
- leaf.parent.type in {syms.comp_for, syms.old_comp_for}
+ leaf.type == token.NAME
+ and leaf.value == 'for'
+ and leaf.parent
+ and leaf.parent.type in {syms.comp_for, syms.old_comp_for}
):
self.delimiters[id(self.previous)] = COMPREHENSION_PRIORITY
elif (
- leaf.type == token.NAME and
- leaf.value == 'if' and
- leaf.parent and
- leaf.parent.type in {syms.comp_if, syms.old_comp_if}
+ leaf.type == token.NAME
+ and leaf.value == 'if'
+ and leaf.parent
+ and leaf.parent.type in {syms.comp_if, syms.old_comp_if}
):
self.delimiters[id(self.previous)] = COMPREHENSION_PRIORITY
+ elif (
+ leaf.type == token.NAME
+ and leaf.value in LOGIC_OPERATORS
+ and leaf.parent
+ ):
+ self.delimiters[id(self.previous)] = LOGIC_PRIORITY
if leaf.type in OPENING_BRACKETS:
self.bracket_match[self.depth, BRACKET[leaf.type]] = leaf
self.depth += 1
self.previous = leaf
def any_open_brackets(self) -> bool:
- """Returns True if there is an yet unmatched open bracket on the line."""
+ """Return True if there is an yet unmatched open bracket on the line."""
return bool(self.bracket_match)
- def max_priority(self, exclude: Iterable[LeafID] =()) -> int:
- """Returns the highest priority of a delimiter found on the line.
+ def max_delimiter_priority(self, exclude: Iterable[LeafID] = ()) -> int:
+ """Return the highest priority of a delimiter found on the line.
Values are consistent with what `is_delimiter()` returns.
"""
@dataclass
class Line:
- depth: int = attrib(default=0)
- leaves: List[Leaf] = attrib(default=Factory(list))
- comments: Dict[LeafID, Leaf] = attrib(default=Factory(dict))
- bracket_tracker: BracketTracker = attrib(default=Factory(BracketTracker))
- inside_brackets: bool = attrib(default=False)
- has_for: bool = attrib(default=False)
- _for_loop_variable: bool = attrib(default=False, init=False)
+ """Holds leaves and comments. Can be printed with `str(line)`."""
+
+ depth: int = 0
+ leaves: List[Leaf] = Factory(list)
+ comments: Dict[LeafID, Leaf] = Factory(dict)
+ bracket_tracker: BracketTracker = Factory(BracketTracker)
+ inside_brackets: bool = False
+ has_for: bool = False
+ _for_loop_variable: 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.value.strip()
if not has_value:
return
@property
def is_comment(self) -> bool:
+ """Is this line a standalone comment?"""
return bool(self) and self.leaves[0].type == STANDALONE_COMMENT
@property
def is_decorator(self) -> bool:
+ """Is this line a decorator?"""
return bool(self) and self.leaves[0].type == token.AT
@property
def is_import(self) -> bool:
+ """Is this an import line?"""
return bool(self) and is_import(self.leaves[0])
@property
def is_class(self) -> bool:
+ """Is this line a class definition?"""
return (
- bool(self) and
- self.leaves[0].type == token.NAME and
- self.leaves[0].value == 'class'
+ bool(self)
+ and self.leaves[0].type == token.NAME
+ and self.leaves[0].value == 'class'
)
@property
def is_def(self) -> bool:
- """Also returns True for async defs."""
+ """Is this a function definition? (Also returns True for async defs.)"""
try:
first_leaf = self.leaves[0]
except IndexError:
except IndexError:
second_leaf = None
return (
- (first_leaf.type == token.NAME and first_leaf.value == 'def') or
- (
- first_leaf.type == token.NAME and
- first_leaf.value == 'async' and
- second_leaf is not None and
- second_leaf.type == token.NAME and
- second_leaf.value == 'def'
+ (first_leaf.type == token.NAME and first_leaf.value == 'def')
+ or (
+ first_leaf.type == token.ASYNC
+ and second_leaf is not None
+ and second_leaf.type == token.NAME
+ and second_leaf.value == 'def'
)
)
@property
def is_flow_control(self) -> bool:
+ """Is this line a flow control statement?
+
+ Those are `return`, `raise`, `break`, and `continue`.
+ """
return (
- bool(self) and
- self.leaves[0].type == token.NAME and
- self.leaves[0].value in FLOW_CONTROL
+ bool(self)
+ and self.leaves[0].type == token.NAME
+ and self.leaves[0].value in FLOW_CONTROL
)
@property
def is_yield(self) -> bool:
+ """Is this line a yield statement?"""
return (
- bool(self) and
- self.leaves[0].type == token.NAME and
- self.leaves[0].value == 'yield'
+ bool(self)
+ and self.leaves[0].type == token.NAME
+ and self.leaves[0].value == 'yield'
)
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 and
- closing.type in CLOSING_BRACKETS
+ self.leaves
+ and self.leaves[-1].type == token.COMMA
+ and closing.type in CLOSING_BRACKETS
):
return False
- if closing.type == token.RSQB or closing.type == token.RBRACE:
+ if closing.type == token.RBRACE:
self.leaves.pop()
return True
+ if closing.type == token.RSQB:
+ comma = self.leaves[-1]
+ if comma.parent and comma.parent.type == syms.listmaker:
+ self.leaves.pop()
+ return True
+
# For parens let's check if it's safe to remove the comma. If the
# trailing one is the only one, we might mistakenly change a tuple
# into a different type by removing the comma.
bracket_depth = leaf.bracket_depth
if bracket_depth == depth and leaf.type == token.COMMA:
commas += 1
+ if leaf.parent and leaf.parent.type == syms.arglist:
+ commas += 1
+ break
+
if commas > 1:
self.leaves.pop()
return True
def maybe_increment_for_loop_variable(self, leaf: Leaf) -> bool:
"""In a for loop, or comprehension, the variables are often unpacks.
- To avoid splitting on the comma in this situation, we will increase
- the depth of tokens between `for` and `in`.
+ 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.has_for = True
return False
def maybe_decrement_after_for_loop_variable(self, leaf: Leaf) -> bool:
- # See `maybe_increment_for_loop_variable` above for explanation.
+ """See `maybe_increment_for_loop_variable` above for explanation."""
if self._for_loop_variable and leaf.type == token.NAME and leaf.value == 'in':
self.bracket_tracker.depth -= 1
self._for_loop_variable = False
appended will appear "too long" when splitting.
"""
if not (
- comment.type == STANDALONE_COMMENT and
- self.bracket_tracker.any_open_brackets()
+ comment.type == STANDALONE_COMMENT
+ and self.bracket_tracker.any_open_brackets()
):
return False
return self.append_comment(comment)
def append_comment(self, comment: Leaf) -> bool:
+ """Add an inline comment to the line."""
if comment.type != token.COMMENT:
return False
return True
def last_non_delimiter(self) -> Leaf:
+ """Return the last non-delimiter on the line. Raise LookupError otherwise."""
for i in range(len(self.leaves)):
last = self.leaves[-i - 1]
if not is_delimiter(last):
raise LookupError("No non-delimiters found")
def __str__(self) -> str:
+ """Render the line."""
if not self:
return '\n'
return res + '\n'
def __bool__(self) -> bool:
+ """Return True if the line has leaves or comments."""
return bool(self.leaves or self.comments)
+class UnformattedLines(Line):
+ """Just like :class:`Line` but stores lines which aren't reformatted."""
+
+ def append(self, leaf: Leaf, preformatted: bool = True) -> None:
+ """Just add a new `leaf` to the end of the lines.
+
+ The `preformatted` argument is ignored.
+
+ Keeps track of indentation `depth`, which is useful when the user
+ says `# fmt: on`. Otherwise, doesn't do anything with the `leaf`.
+ """
+ try:
+ list(generate_comments(leaf))
+ except FormatOn as f_on:
+ self.leaves.append(f_on.leaf_from_consumed(leaf))
+ raise
+
+ self.leaves.append(leaf)
+ if leaf.type == token.INDENT:
+ self.depth += 1
+ elif leaf.type == token.DEDENT:
+ self.depth -= 1
+
+ def __str__(self) -> str:
+ """Render unformatted lines from leaves which were added with `append()`.
+
+ `depth` is not used for indentation in this case.
+ """
+ if not self:
+ return '\n'
+
+ res = ''
+ for leaf in self.leaves:
+ res += str(leaf)
+ return res
+
+ def append_comment(self, comment: Leaf) -> bool:
+ """Not implemented in this class. Raises `NotImplementedError`."""
+ raise NotImplementedError("Unformatted lines don't store comments separately.")
+
+ def maybe_remove_trailing_comma(self, closing: Leaf) -> bool:
+ """Does nothing and returns False."""
+ return False
+
+ def maybe_increment_for_loop_variable(self, leaf: Leaf) -> bool:
+ """Does nothing and returns False."""
+ return False
+
+ def maybe_adapt_standalone_comment(self, comment: Leaf) -> bool:
+ """Does nothing and returns False."""
+ return False
+
+
@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.
+ Note: this tracker works on lines that haven't been split yet. It assumes
+ the prefix of the first leaf consists of optional newlines. Those newlines
+ are consumed by `maybe_empty_lines()` and included in the computation.
"""
- previous_line: Optional[Line] = attrib(default=None)
- previous_after: int = attrib(default=0)
- previous_defs: List[int] = attrib(default=Factory(list))
+ 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]:
- """Returns the number of extra empty lines before and after the `current_line`.
+ """Return the number of extra empty lines before and after the `current_line`.
- This is for separating `def`, `async def` and `class` with extra empty lines
- (two on module-level), as well as providing an extra empty line after flow
- control keywords to make them more prominent.
+ This is for separating `def`, `async def` and `class` with extra empty
+ lines (two on module-level), as well as providing an extra empty line
+ after flow control keywords to make them more prominent.
"""
+ if isinstance(current_line, UnformattedLines):
+ return 0, 0
+
before, after = self._maybe_empty_lines(current_line)
+ before -= self.previous_after
self.previous_after = after
self.previous_line = current_line
return before, after
def _maybe_empty_lines(self, current_line: Line) -> Tuple[int, int]:
- before = 0
+ max_allowed = 1
+ if current_line.depth == 0:
+ max_allowed = 2
+ if current_line.leaves:
+ # Consume the first leaf's extra newlines.
+ first_leaf = current_line.leaves[0]
+ before = first_leaf.prefix.count('\n')
+ before = min(before, max_allowed)
+ first_leaf.prefix = ''
+ else:
+ before = 0
depth = current_line.depth
while self.previous_defs and self.previous_defs[-1] >= depth:
self.previous_defs.pop()
- before = (1 if depth else 2) - self.previous_after
+ before = 1 if depth else 2
is_decorator = current_line.is_decorator
if is_decorator or current_line.is_def or current_line.is_class:
if not is_decorator:
newlines = 2
if current_line.depth:
newlines -= 1
- newlines -= self.previous_after
return newlines, 0
if current_line.is_flow_control:
return before, 1
if (
- self.previous_line and
- self.previous_line.is_import and
- not current_line.is_import and
- depth == self.previous_line.depth
+ self.previous_line
+ and self.previous_line.is_import
+ and not current_line.is_import
+ and depth == self.previous_line.depth
):
return (before or 1), 0
if (
- self.previous_line and
- self.previous_line.is_yield and
- (not current_line.is_yield or depth != self.previous_line.depth)
+ self.previous_line
+ and self.previous_line.is_yield
+ and (not current_line.is_yield or depth != self.previous_line.depth)
):
return (before or 1), 0
Note: destroys the tree it's visiting by mutating prefixes of its leaves
in ways that will no longer stringify to valid Python code on the tree.
"""
- current_line: Line = attrib(default=Factory(Line))
- standalone_comments: List[Leaf] = attrib(default=Factory(list))
+ current_line: Line = Factory(Line)
- def line(self, indent: int = 0) -> Iterator[Line]:
+ def line(self, indent: int = 0, type: Type[Line] = Line) -> Iterator[Line]:
"""Generate a line.
If the line is empty, only emit if it makes sense.
If any lines were generated, set up a new current_line.
"""
if not self.current_line:
- self.current_line.depth += indent
+ if self.current_line.__class__ == type:
+ self.current_line.depth += indent
+ else:
+ self.current_line = type(depth=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)
+ self.current_line = type(depth=complete_line.depth + indent)
yield complete_line
+ def visit(self, node: LN) -> Iterator[Line]:
+ """Main method to visit `node` and its children.
+
+ Yields :class:`Line` objects.
+ """
+ if isinstance(self.current_line, UnformattedLines):
+ # File contained `# fmt: off`
+ yield from self.visit_unformatted(node)
+
+ else:
+ yield from super().visit(node)
+
def visit_default(self, node: LN) -> Iterator[Line]:
+ """Default `visit_*()` implementation. Recurses to children of `node`."""
if isinstance(node, Leaf):
- for comment in generate_comments(node):
- if self.current_line.bracket_tracker.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, to be processed later (see
- # docstring in `generate_comments()`
- self.standalone_comments.append(comment)
- normalize_prefix(node)
- if node.type not in WHITESPACE:
- for comment in self.standalone_comments:
- yield from self.line()
-
- self.current_line.append(comment)
- yield from self.line()
-
- self.standalone_comments = []
- self.current_line.append(node)
+ any_open_brackets = self.current_line.bracket_tracker.any_open_brackets()
+ try:
+ 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()
+
+ except FormatOff as f_off:
+ f_off.trim_prefix(node)
+ yield from self.line(type=UnformattedLines)
+ yield from self.visit(node)
+
+ except FormatOn as f_on:
+ # This only happens here if somebody says "fmt: on" multiple
+ # times in a row.
+ f_on.trim_prefix(node)
+ yield from self.visit_default(node)
+
+ else:
+ normalize_prefix(node, inside_brackets=any_open_brackets)
+ if node.type not in WHITESPACE:
+ self.current_line.append(node)
yield from super().visit_default(node)
- def visit_suite(self, node: Node) -> Iterator[Line]:
- """Body of a statement after a colon."""
- children = iter(node.children)
- # Process newline before indenting. It might contain an inline
- # comment that should go right after the colon.
- newline = next(children)
- yield from self.visit(newline)
+ def visit_INDENT(self, node: 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)
- for child in children:
- yield from self.visit(child)
-
+ def visit_DEDENT(self, node: Node) -> Iterator[Line]:
+ """Decrease indentation level, maybe yield a line."""
+ # DEDENT has no value. Additionally, in blib2to3 it never holds comments.
yield from self.line(-1)
def visit_stmt(self, node: Node, keywords: Set[str]) -> Iterator[Line]:
"""Visit a statement.
- The relevant Python language keywords for this statement are NAME leaves
- within it.
+ This implementation is shared for `if`, `while`, `for`, `try`, `except`,
+ `def`, `with`, and `class`.
+
+ The relevant Python language `keywords` for a given statement will be NAME
+ leaves within it. This methods puts those on a separate line.
"""
for child in node.children:
if child.type == token.NAME and child.value in keywords: # type: ignore
yield from self.visit(child)
def visit_simple_stmt(self, node: Node) -> Iterator[Line]:
- """A statement without nested statements."""
+ """Visit a statement without nested statements."""
is_suite_like = node.parent and node.parent.type in STATEMENT
if is_suite_like:
yield from self.line(+1)
yield from self.visit_default(node)
def visit_async_stmt(self, node: Node) -> Iterator[Line]:
+ """Visit `async def`, `async for`, `async with`."""
yield from self.line()
children = iter(node.children)
for child in children:
yield from self.visit(child)
- if child.type == token.NAME and child.value == 'async': # type: ignore
+ if child.type == token.ASYNC:
break
internal_stmt = next(children)
yield from self.visit(child)
def visit_decorators(self, node: Node) -> Iterator[Line]:
+ """Visit decorators."""
for child in node.children:
yield from self.line()
yield from self.visit(child)
def visit_SEMI(self, leaf: Leaf) -> Iterator[Line]:
+ """Remove a semicolon and put the other statement on a separate line."""
yield from self.line()
def visit_ENDMARKER(self, leaf: Leaf) -> Iterator[Line]:
+ """End of file. Process outstanding comments and end with a newline."""
yield from self.visit_default(leaf)
yield from self.line()
+ def visit_unformatted(self, node: LN) -> Iterator[Line]:
+ """Used when file contained a `# fmt: off`."""
+ if isinstance(node, Node):
+ for child in node.children:
+ yield from self.visit(child)
+
+ else:
+ try:
+ self.current_line.append(node)
+ except FormatOn as f_on:
+ f_on.trim_prefix(node)
+ yield from self.line()
+ yield from self.visit(node)
+
def __attrs_post_init__(self) -> None:
"""You are in a twisty little maze of passages."""
v = self.visit_stmt
OPENING_BRACKETS = set(BRACKET.keys())
CLOSING_BRACKETS = set(BRACKET.values())
BRACKETS = OPENING_BRACKETS | CLOSING_BRACKETS
-ALWAYS_NO_SPACE = CLOSING_BRACKETS | {token.COMMA, token.COLON, STANDALONE_COMMENT}
+ALWAYS_NO_SPACE = CLOSING_BRACKETS | {token.COMMA, STANDALONE_COMMENT}
def whitespace(leaf: Leaf) -> str: # noqa C901
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}:
+ 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:
+ return SPACE if prevp.type == token.COMMA else NO
+
if prevp.type == token.EQUAL:
- if prevp.parent and prevp.parent.type in {
- syms.typedargslist,
- syms.varargslist,
- syms.parameters,
- syms.arglist,
- syms.argument,
- }:
- return NO
+ 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 == token.DOUBLESTAR:
if prevp.parent and prevp.parent.type in {
- syms.typedargslist,
- syms.varargslist,
- syms.parameters,
syms.arglist,
+ syms.argument,
syms.dictsetmaker,
+ syms.parameters,
+ syms.typedargslist,
+ syms.varargslist,
}:
return NO
elif prevp.type == token.COLON:
- if prevp.parent and prevp.parent.type == syms.subscript:
+ if prevp.parent and prevp.parent.type in {syms.subscript, syms.sliceop}:
return NO
- elif prevp.parent and prevp.parent.type in {syms.factor, syms.star_expr}:
+ elif (
+ prevp.parent
+ and prevp.parent.type in {syms.factor, syms.star_expr}
+ and prevp.type in MATH_OPERATORS
+ ):
+ return NO
+
+ elif (
+ prevp.type == token.RIGHTSHIFT
+ and prevp.parent
+ and prevp.parent.type == syms.shift_expr
+ and prevp.prev_sibling
+ and prevp.prev_sibling.type == token.NAME
+ and prevp.prev_sibling.value == 'print' # type: ignore
+ ):
+ # Python 2 print chevron
return NO
elif prev.type in OPENING_BRACKETS:
if not prev or prev.type != token.COMMA:
return NO
- if p.type == syms.varargslist:
+ elif p.type == syms.varargslist:
# lambdas
if t == token.RPAR:
return NO
return NO
- elif prev.type == token.COLON:
+ else:
return NO
elif p.type == syms.atom:
return NO
elif (
- p.type == syms.listmaker or
- p.type == syms.testlist_gexp or
- p.type == syms.subscriptlist
+ p.type == syms.listmaker
+ or p.type == syms.testlist_gexp
+ or p.type == syms.subscriptlist
):
# list interior, including unpacking
if not prev:
def preceding_leaf(node: Optional[LN]) -> Optional[Leaf]:
- """Returns the first leaf that precedes `node`, if any."""
+ """Return the first leaf that precedes `node`, if any."""
while node:
res = node.prev_sibling
if res:
def is_delimiter(leaf: Leaf) -> int:
- """Returns the priority of the `leaf` delimiter. Returns 0 if not delimiter.
+ """Return the priority of the `leaf` delimiter. Return 0 if not delimiter.
Higher numbers are higher priority.
"""
if leaf.type == token.COMMA:
return COMMA_PRIORITY
- if leaf.type == token.NAME and leaf.value in LOGIC_OPERATORS:
- return LOGIC_PRIORITY
-
if leaf.type in COMPARATORS:
return COMPARATOR_PRIORITY
if (
- leaf.type in MATH_OPERATORS and
- leaf.parent and
- leaf.parent.type not in {syms.factor, syms.star_expr}
+ leaf.type in MATH_OPERATORS
+ and leaf.parent
+ and leaf.parent.type not in {syms.factor, syms.star_expr}
):
return MATH_PRIORITY
def generate_comments(leaf: Leaf) -> Iterator[Leaf]:
- """Cleans the prefix of the `leaf` and generates comments from it, if any.
+ """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
Inline comments are emitted as regular token.COMMENT leaves. Standalone
are emitted with a fake STANDALONE_COMMENT token identifier.
"""
- if not leaf.prefix:
+ p = leaf.prefix
+ if not p:
return
- if '#' not in leaf.prefix:
+ if '#' not in p:
return
- before_comment, content = leaf.prefix.split('#', 1)
- content = content.rstrip()
- if content and (content[0] not in {' ', '!', '#'}):
- content = ' ' + content
- is_standalone_comment = (
- '\n' in before_comment or '\n' in content or leaf.type == token.DEDENT
- )
- if not is_standalone_comment:
- # simple trailing comment
- yield Leaf(token.COMMENT, value='#' + content)
- return
-
- for line in ('#' + content).split('\n'):
+ consumed = 0
+ nlines = 0
+ for index, line in enumerate(p.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('#'):
continue
- yield Leaf(STANDALONE_COMMENT, line)
+ if index == 0 and leaf.type != token.ENDMARKER:
+ comment_type = token.COMMENT # simple trailing comment
+ else:
+ comment_type = STANDALONE_COMMENT
+ comment = make_comment(line)
+ yield Leaf(comment_type, comment, prefix='\n' * nlines)
+
+ if comment in {'# fmt: on', '# yapf: enable'}:
+ raise FormatOn(consumed)
+
+ if comment in {'# fmt: off', '# yapf: disable'}:
+ raise FormatOff(consumed)
+
+ nlines = 0
+
+
+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, py36: bool = False
) -> Iterator[Line]:
- """Splits a `line` into potentially many lines.
+ """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
If `py36` is True, splitting may generate syntax that is only compatible
with Python 3.6 and later.
"""
+ if isinstance(line, UnformattedLines):
+ yield line
+ return
+
line_str = str(line).strip('\n')
if len(line_str) <= line_length and '\n' not in line_str:
yield line
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 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)
current_leaves = body_leaves
# Since body is a new indent level, remove spurious leading whitespace.
if body_leaves:
- normalize_prefix(body_leaves[0])
+ normalize_prefix(body_leaves[0], inside_brackets=True)
# Build the new lines.
for result, leaves in (
(head, head_leaves), (body, body_leaves), (tail, tail_leaves)
comment_after = line.comments.get(id(leaf))
if comment_after:
result.append(comment_after, preformatted=True)
- split_succeeded_or_raise(head, body, tail)
+ bracket_split_succeeded_or_raise(head, body, tail)
for result in (head, body, tail):
if result:
yield result
head_leaves.reverse()
# Since body is a new indent level, remove spurious leading whitespace.
if body_leaves:
- normalize_prefix(body_leaves[0])
+ normalize_prefix(body_leaves[0], inside_brackets=True)
# Build the new lines.
for result, leaves in (
(head, head_leaves), (body, body_leaves), (tail, tail_leaves)
comment_after = line.comments.get(id(leaf))
if comment_after:
result.append(comment_after, preformatted=True)
- split_succeeded_or_raise(head, body, tail)
+ bracket_split_succeeded_or_raise(head, body, tail)
for result in (head, body, tail):
if result:
yield result
-def split_succeeded_or_raise(head: Line, body: Line, tail: Line) -> None:
+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:
This kind of split doesn't increase indentation.
If `py36` is True, the split will add trailing commas also in function
- signatures that contain * and **.
+ signatures that contain `*` and `**`.
"""
try:
last_leaf = line.leaves[-1]
delimiters = line.bracket_tracker.delimiters
try:
- delimiter_priority = line.bracket_tracker.max_priority(exclude={id(last_leaf)})
+ delimiter_priority = line.bracket_tracker.max_delimiter_priority(
+ exclude={id(last_leaf)}
+ )
except ValueError:
raise CannotSplit("No delimiters found")
current_line.append(comment_after, preformatted=True)
lowest_depth = min(lowest_depth, leaf.bracket_depth)
if (
- leaf.bracket_depth == lowest_depth and
- leaf.type == token.STAR or
- leaf.type == token.DOUBLESTAR
+ leaf.bracket_depth == lowest_depth
+ and leaf.type == token.STAR
+ or leaf.type == token.DOUBLESTAR
):
trailing_comma_safe = trailing_comma_safe and py36
leaf_priority = delimiters.get(id(leaf))
if leaf_priority == delimiter_priority:
- normalize_prefix(current_line.leaves[0])
+ normalize_prefix(current_line.leaves[0], inside_brackets=True)
yield current_line
current_line = Line(depth=line.depth, inside_brackets=line.inside_brackets)
if current_line:
if (
- delimiter_priority == COMMA_PRIORITY and
- current_line.leaves[-1].type != token.COMMA and
- trailing_comma_safe
+ delimiter_priority == COMMA_PRIORITY
+ and current_line.leaves[-1].type != token.COMMA
+ and trailing_comma_safe
):
current_line.append(Leaf(token.COMMA, ','))
- normalize_prefix(current_line.leaves[0])
+ normalize_prefix(current_line.leaves[0], inside_brackets=True)
yield current_line
def is_import(leaf: Leaf) -> bool:
- """Returns True if the given leaf starts an import statement."""
+ """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)
+ 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 normalize_prefix(leaf: Leaf) -> None:
- """Leave existing extra newlines for imports. Remove everything else."""
- if is_import(leaf):
- spl = leaf.prefix.split('#', 1)
- nl_count = spl[0].count('\n')
- if len(spl) > 1:
- # Skip one newline since it was for a standalone comment.
- nl_count -= 1
- leaf.prefix = '\n' * nl_count
- return
+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 is_python36(node: Node) -> bool:
- """Returns True if the current file is using Python 3.6+ features.
+ """Return True if the current file is using Python 3.6+ features.
Currently looking for:
- f-strings; and
return True
elif (
- n.type == syms.typedargslist and
- n.children and
- n.children[-1].type == token.COMMA
+ n.type == syms.typedargslist
+ and n.children
+ and n.children[-1].type == token.COMMA
):
for ch in n.children:
if ch.type == token.STAR or ch.type == token.DOUBLESTAR:
def gen_python_files_in_dir(path: Path) -> Iterator[Path]:
+ """Generate all files under `path` which aren't under BLACKLISTED_DIRECTORIES
+ and have one of the PYTHON_EXTENSIONS.
+ """
for child in path.iterdir():
if child.is_dir():
if child.name in BLACKLISTED_DIRECTORIES:
@dataclass
class Report:
- """Provides a reformatting counter."""
- change_count: int = attrib(default=0)
- same_count: int = attrib(default=0)
- failure_count: int = attrib(default=0)
+ """Provides a reformatting counter. Can be rendered with `str(report)`."""
+ check: bool = False
+ change_count: int = 0
+ same_count: int = 0
+ failure_count: int = 0
def done(self, src: Path, changed: bool) -> None:
"""Increment the counter for successful reformatting. Write out a message."""
if changed:
- out(f'reformatted {src}')
+ reformatted = 'would reformat' if self.check else 'reformatted'
+ out(f'{reformatted} {src}')
self.change_count += 1
else:
out(f'{src} already well formatted, good job.', bold=False)
@property
def return_code(self) -> int:
- """Which return code should the app use considering the current state."""
+ """Return the exit code that the app should use.
+
+ This considers the current state of changed files and failures:
+ - if there were any failures, return 123;
+ - if any files were changed and --check is being used, return 1;
+ - otherwise return 0.
+ """
# According to http://tldp.org/LDP/abs/html/exitcodes.html starting with
# 126 we have special returncodes reserved by the shell.
if self.failure_count:
return 123
- elif self.change_count:
+ elif self.change_count and self.check:
return 1
return 0
def __str__(self) -> str:
- """A color report of the current state.
+ """Render a color report of the current state.
Use `click.unstyle` to remove colors.
"""
+ if self.check:
+ 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)
+ click.style(f'{self.change_count} file{s} {reformatted}', bold=True)
)
if self.same_count:
s = 's' if self.same_count > 1 else ''
- report.append(f'{self.same_count} file{s} left unchanged')
+ 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 to reformat', fg='red'
- )
+ click.style(f'{self.failure_count} file{s} {failed}', fg='red')
)
return ', '.join(report) + '.'
def assert_equivalent(src: str, dst: str) -> None:
- """Raises AssertionError if `src` and `dst` aren't equivalent.
-
- This is a temporary sanity check until Black becomes stable.
- """
+ """Raise AssertionError if `src` and `dst` aren't equivalent."""
import ast
import traceback
try:
src_ast = ast.parse(src)
except Exception as exc:
- raise AssertionError(f"cannot parse source: {exc}") from None
+ major, minor = sys.version_info[:2]
+ raise AssertionError(
+ f"cannot use --safe with this file; failed to parse source file "
+ f"with Python {major}.{minor}'s builtin AST. Re-run with --fast "
+ f"or stop using deprecated Python 2 syntax. AST error message: {exc}"
+ )
try:
dst_ast = ast.parse(dst)
raise AssertionError(
f"INTERNAL ERROR: Black produced invalid code: {exc}. "
f"Please report a bug on https://github.com/ambv/black/issues. "
- f"This invalid output might be helpful: {log}",
+ f"This invalid output might be helpful: {log}"
) from None
src_ast_str = '\n'.join(_v(src_ast))
f"INTERNAL ERROR: Black produced code that is not equivalent to "
f"the source. "
f"Please report a bug on https://github.com/ambv/black/issues. "
- f"This diff might be helpful: {log}",
+ f"This diff might be helpful: {log}"
) from None
def assert_stable(src: str, dst: str, line_length: int) -> None:
- """Raises AssertionError if `dst` reformats differently the second time.
-
- This is a temporary sanity check until Black becomes stable.
- """
+ """Raise AssertionError if `dst` reformats differently the second time."""
newdst = format_str(dst, line_length=line_length)
if dst != newdst:
log = dump_to_file(
f"INTERNAL ERROR: Black produced different code on the second pass "
f"of the formatter. "
f"Please report a bug on https://github.com/ambv/black/issues. "
- f"This diff might be helpful: {log}",
+ f"This diff might be helpful: {log}"
) from None
def dump_to_file(*output: str) -> str:
- """Dumps `output` to a temporary file. Returns path to the file."""
+ """Dump `output` to a temporary file. Return path to the file."""
import tempfile
with tempfile.NamedTemporaryFile(
def diff(a: str, b: str, a_name: str, b_name: str) -> str:
- """Returns a udiff string between strings `a` and `b`."""
+ """Return a unified diff string between strings `a` and `b`."""
import difflib
a_lines = [line + '\n' for line in a.split('\n')]
projects / etc / vim.git / blobdiff