import asyncio import pickle from asyncio.base_events import BaseEventLoop from concurrent.futures import Executor, ProcessPoolExecutor from enum import Enum from functools import partial, wraps import keyword import logging from multiprocessing import Manager import os from pathlib import Path import re import tokenize import signal import sys from typing import ( Any, Callable, Collection, Dict, Generic, Iterable, Iterator, List, Optional, Pattern, Set, Tuple, Type, TypeVar, Union, ) from appdirs import user_cache_dir from attr import dataclass, Factory import click # lib2to3 fork from blib2to3.pytree import Node, Leaf, type_repr from blib2to3 import pygram, pytree from blib2to3.pgen2 import driver, token from blib2to3.pgen2.parse import ParseError __version__ = "18.4a6" DEFAULT_LINE_LENGTH = 88 # types syms = pygram.python_symbols FileContent = str Encoding = str Depth = int NodeType = int LeafID = int Priority = int Index = int LN = Union[Leaf, Node] SplitFunc = Callable[["Line", bool], 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) class NothingChanged(UserWarning): """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 :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.""" class WriteBack(Enum): NO = 0 YES = 1 DIFF = 2 class Changed(Enum): NO = 0 CACHED = 1 YES = 2 @click.command() @click.option( "-l", "--line-length", type=int, default=DEFAULT_LINE_LENGTH, help="How many character per line to allow.", show_default=True, ) @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( "-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.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 ), ) @click.pass_context def main( ctx: click.Context, line_length: int, check: bool, diff: bool, fast: bool, quiet: bool, src: List[str], ) -> None: """The uncompromising code formatter.""" sources: List[Path] = [] for s in src: p = Path(s) if p.is_dir(): sources.extend(gen_python_files_in_dir(p)) 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 check and not diff: write_back = WriteBack.NO elif diff: write_back = WriteBack.DIFF else: write_back = WriteBack.YES report = Report(check=check, quiet=quiet) if len(sources) == 0: out("No paths given. Nothing to do 😴") ctx.exit(0) return elif len(sources) == 1: reformat_one(sources[0], line_length, fast, write_back, report) else: loop = asyncio.get_event_loop() executor = ProcessPoolExecutor(max_workers=os.cpu_count()) try: loop.run_until_complete( schedule_formatting( sources, line_length, fast, write_back, report, loop, executor ) ) finally: shutdown(loop) if not quiet: out("All done! ✨ 🍰 ✨") click.echo(str(report)) ctx.exit(report.return_code) def reformat_one( src: Path, line_length: int, fast: bool, write_back: WriteBack, report: "Report" ) -> None: """Reformat a single file under `src` without spawning child processes. If `quiet` is True, non-error messages are not output. `line_length`, `write_back`, and `fast` options are passed to :func:`format_file_in_place`. """ try: changed = Changed.NO if not src.is_file() and str(src) == "-": if format_stdin_to_stdout( line_length=line_length, fast=fast, write_back=write_back ): changed = Changed.YES else: cache: Cache = {} if write_back != WriteBack.DIFF: cache = read_cache(line_length) src = src.resolve() if src in cache and cache[src] == get_cache_info(src): changed = Changed.CACHED if ( changed is not Changed.CACHED and format_file_in_place( src, line_length=line_length, fast=fast, write_back=write_back ) ): changed = Changed.YES if write_back == WriteBack.YES and changed is not Changed.NO: write_cache(cache, [src], line_length) report.done(src, changed) except Exception as exc: report.failed(src, str(exc)) async def schedule_formatting( sources: List[Path], line_length: int, fast: bool, write_back: WriteBack, report: "Report", loop: BaseEventLoop, executor: Executor, ) -> None: """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`. """ cache: Cache = {} if write_back != WriteBack.DIFF: cache = read_cache(line_length) sources, cached = filter_cached(cache, sources) for src in cached: report.done(src, Changed.CACHED) cancelled = [] formatted = [] if sources: lock = None if write_back == WriteBack.DIFF: # For diff output, we need locks to ensure we don't interleave output # from different processes. manager = Manager() lock = manager.Lock() tasks = { src: loop.run_in_executor( executor, format_file_in_place, src, line_length, fast, write_back, lock ) for src in sources } _task_values = list(tasks.values()) try: loop.add_signal_handler(signal.SIGINT, cancel, _task_values) loop.add_signal_handler(signal.SIGTERM, cancel, _task_values) except NotImplementedError: # There are no good alternatives for these on Windows pass await asyncio.wait(_task_values) for src, task in tasks.items(): if not task.done(): report.failed(src, "timed out, cancelling") task.cancel() cancelled.append(task) elif task.cancelled(): cancelled.append(task) elif task.exception(): report.failed(src, str(task.exception())) else: formatted.append(src) report.done(src, Changed.YES if task.result() else Changed.NO) if cancelled: await asyncio.gather(*cancelled, loop=loop, return_exceptions=True) if write_back == WriteBack.YES and formatted: write_cache(cache, formatted, line_length) def format_file_in_place( src: Path, line_length: int, fast: bool, 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 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: dst_contents = format_file_contents( src_contents, line_length=line_length, fast=fast ) except NothingChanged: return False if write_back == write_back.YES: with open(src, "w", encoding=src_buffer.encoding) as f: f.write(dst_contents) elif write_back == write_back.DIFF: src_name = f"{src} (original)" dst_name = f"{src} (formatted)" diff_contents = diff(src_contents, dst_contents, src_name, dst_name) if lock: lock.acquire() try: sys.stdout.write(diff_contents) finally: if lock: lock.release() return True def format_stdin_to_stdout( line_length: int, fast: bool, write_back: WriteBack = WriteBack.NO ) -> 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`. """ src = sys.stdin.read() dst = src try: dst = format_file_contents(src, line_length=line_length, fast=fast) return True except NothingChanged: return False finally: if write_back == WriteBack.YES: sys.stdout.write(dst) elif write_back == WriteBack.DIFF: src_name = " (original)" dst_name = " (formatted)" sys.stdout.write(diff(src, dst, src_name, dst_name)) 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 dst_contents = format_str(src_contents, line_length=line_length) if src_contents == dst_contents: raise NothingChanged if not fast: assert_equivalent(src_contents, dst_contents) assert_stable(src_contents, dst_contents, line_length=line_length) return dst_contents def format_str(src_contents: str, line_length: int) -> FileContent: """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 = "" lines = LineGenerator() elt = EmptyLineTracker() py36 = is_python36(src_node) empty_line = Line() after = 0 for current_line in lines.visit(src_node): for _ in range(after): dst_contents += str(empty_line) before, after = elt.maybe_empty_lines(current_line) for _ in range(before): dst_contents += str(empty_line) 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, ] def lib2to3_parse(src_txt: str) -> Node: """Given a string with source, return the lib2to3 Node.""" grammar = pygram.python_grammar_no_print_statement if src_txt[-1] != "\n": nl = "\r\n" if "\r\n" in src_txt[:1024] else "\n" src_txt += nl for grammar in GRAMMARS: 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 = "" exc = ValueError(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: 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} FLOW_CONTROL = {"return", "raise", "break", "continue"} 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 LOGIC_OPERATORS = {"and", "or"} COMPARATORS = { token.LESS, token.GREATER, token.EQEQUAL, token.NOTEQUAL, token.LESSEQUAL, token.GREATEREQUAL, } MATH_OPERATORS = { token.PLUS, token.MINUS, token.STAR, token.SLASH, token.VBAR, token.AMPER, token.PERCENT, token.CIRCUMFLEX, token.TILDE, token.LEFTSHIFT, token.RIGHTSHIFT, token.DOUBLESTAR, token.DOUBLESLASH, } STARS = {token.STAR, token.DOUBLESTAR} 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, } 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, } COMPREHENSION_PRIORITY = 20 COMMA_PRIORITY = 10 TERNARY_PRIORITY = 7 LOGIC_PRIORITY = 5 STRING_PRIORITY = 4 COMPARATOR_PRIORITY = 3 MATH_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_variable: bool = False _lambda_arguments: bool = False 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] = ()) -> int: """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 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_variable = True 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_variable and leaf.type == token.NAME and leaf.value == "in": self.depth -= 1 self._for_loop_variable = False 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_arguments = True 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_arguments and leaf.type == token.COLON: self.depth -= 1 self._lambda_arguments = False 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: List[Tuple[Index, Leaf]] = Factory(list) bracket_tracker: BracketTracker = Factory(BracketTracker) inside_brackets: 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_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_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 ) @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" ) @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 == ")" ) 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 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 ): return False if closing.type == token.RBRACE: self.remove_trailing_comma() return True if closing.type == token.RSQB: comma = self.leaves[-1] if comma.parent and comma.parent.type == syms.listmaker: self.remove_trailing_comma() return True # For parens let's check if it's safe to remove the comma. # Imports are always safe. if self.is_import: self.remove_trailing_comma() return True # Otheriwsse, if the trailing one is the only one, we might mistakenly # change a tuple into a different type by removing the comma. depth = closing.bracket_depth + 1 commas = 0 opening = closing.opening_bracket for _opening_index, leaf in enumerate(self.leaves): if leaf is opening: break else: return False for leaf in self.leaves[_opening_index + 1 :]: if leaf is closing: break bracket_depth = leaf.bracket_depth if bracket_depth == depth and leaf.type == token.COMMA: commas += 1 if leaf.parent and leaf.parent.type == syms.arglist: commas += 1 break if commas > 1: self.remove_trailing_comma() return True return False def append_comment(self, comment: Leaf) -> bool: """Add an inline or standalone comment to the line.""" if ( comment.type == STANDALONE_COMMENT and self.bracket_tracker.any_open_brackets() ): comment.prefix = "" return False if comment.type != token.COMMENT: return False after = len(self.leaves) - 1 if after == -1: comment.type = STANDALONE_COMMENT comment.prefix = "" return False else: self.comments.append((after, comment)) return True def comments_after(self, leaf: Leaf) -> Iterator[Leaf]: """Generate comments that should appear directly after `leaf`.""" for _leaf_index, _leaf in enumerate(self.leaves): if leaf is _leaf: break else: return for index, comment_after in self.comments: if _leaf_index == index: yield comment_after def remove_trailing_comma(self) -> None: """Remove the trailing comma and moves the comments attached to it.""" comma_index = len(self.leaves) - 1 for i in range(len(self.comments)): comment_index, comment = self.comments[i] if comment_index == comma_index: self.comments[i] = (comma_index - 1, comment) self.leaves.pop() def is_complex_subscript(self, leaf: Leaf) -> bool: """Return True iff `leaf` is part of a slice with non-trivial exprs.""" open_lsqb = ( leaf if leaf.type == token.LSQB else self.bracket_tracker.get_open_lsqb() ) if open_lsqb is None: return False subscript_start = open_lsqb.next_sibling if ( isinstance(subscript_start, Node) and 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 self.comments: 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) 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 @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. """ 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), 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]: 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 is_decorator = current_line.is_decorator if is_decorator or current_line.is_def or current_line.is_class: if not is_decorator: self.previous_defs.append(depth) if self.previous_line is None: # Don't insert empty lines before the first line in the file. return 0, 0 if self.previous_line.is_decorator: return 0, 0 if ( self.previous_line.is_comment and self.previous_line.depth == current_line.depth and before == 0 ): return 0, 0 newlines = 2 if current_line.depth: newlines -= 1 return newlines, 0 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 return before, 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. """ current_line: Line = Factory(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 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: 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 = 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): 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 == token.STRING: normalize_string_quotes(node) if node.type not in WHITESPACE: self.current_line.append(node) yield from super().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`, and `assert`. 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 pairs of nodes where invisible parentheses should be put. Keys hold nodes after which opening parentheses should be put, values hold nodes before which closing parentheses 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_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: yield from self.line(+1) yield from self.visit_default(node) yield from self.line(-1) else: 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_import_from(self, node: Node) -> Iterator[Line]: """Visit import_from and maybe put invisible parentheses. This is separate from `visit_stmt` because import statements don't support arbitrary atoms and thus handling of parentheses is custom. """ check_lpar = False for index, child in enumerate(node.children): if check_lpar: if child.type == token.LPAR: # make parentheses invisible child.value = "" # type: ignore node.children[-1].value = "" # type: ignore else: # insert invisible parentheses node.insert_child(index, Leaf(token.LPAR, "")) node.append_child(Leaf(token.RPAR, "")) break check_lpar = ( child.type == token.NAME and child.value == "import" # type: ignore ) for child in node.children: 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) if node.type == token.ENDMARKER: # somebody decided not to put a final `# fmt: on` yield from self.line() 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"}) 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_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 STARS: 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} | STARS: 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 == token.NAME or t == token.NUMBER: 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 is_split_after_delimiter(leaf: Leaf, previous: Leaf = None) -> int: """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: Leaf = None) -> int: """Return the priority of the `leaf` delimiter, given a line before after 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 in MATH_OPERATORS and leaf.parent and leaf.parent.type not in {syms.factor, syms.star_expr} ): return MATH_PRIORITY 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 == token.NAME and leaf.value == "for" and leaf.parent and leaf.parent.type in {syms.comp_for, syms.old_comp_for} ): return COMPREHENSION_PRIORITY if ( leaf.type == token.NAME and leaf.value == "if" and leaf.parent and leaf.parent.type in {syms.comp_if, syms.old_comp_if} ): return COMPREHENSION_PRIORITY if ( leaf.type == token.NAME and leaf.value in {"if", "else"} and leaf.parent and leaf.parent.type == syms.test ): return TERNARY_PRIORITY if leaf.type == token.NAME and leaf.value in LOGIC_OPERATORS and leaf.parent: return LOGIC_PRIORITY return 0 def generate_comments(leaf: Leaf) -> 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. """ p = leaf.prefix if not p: return if "#" not in p: return 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 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"}: if comment_type == STANDALONE_COMMENT: raise FormatOff(consumed) prev = preceding_leaf(leaf) if not prev or prev.type in WHITESPACE: # standalone comment in disguise 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]: """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. If `py36` is True, splitting may generate syntax that is only compatible with Python 3.6 and later. """ if isinstance(line, UnformattedLines) or line.is_comment: yield line return line_str = str(line).strip("\n") if ( len(line_str) <= line_length and "\n" not in line_str # multiline strings and not line.contains_standalone_comments() ): yield line return split_funcs: List[SplitFunc] if line.is_def: split_funcs = [left_hand_split] elif line.is_import: split_funcs = [explode_split] elif line.inside_brackets: split_funcs = [delimiter_split, standalone_comment_split, right_hand_split] else: split_funcs = [right_hand_split] 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, py36): 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, py36=py36) ) except CannotSplit as cs: continue else: yield from result break else: yield line def left_hand_split(line: Line, py36: bool = False) -> 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. """ head = Line(depth=line.depth) body = Line(depth=line.depth + 1, inside_brackets=True) tail = Line(depth=line.depth) tail_leaves: List[Leaf] = [] body_leaves: List[Leaf] = [] head_leaves: List[Leaf] = [] current_leaves = head_leaves matching_bracket = None for leaf in line.leaves: if ( current_leaves is body_leaves and leaf.type in CLOSING_BRACKETS and leaf.opening_bracket is matching_bracket ): 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 # Since body is a new indent level, remove spurious leading whitespace. if body_leaves: 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): for leaf in leaves: result.append(leaf, preformatted=True) for comment_after in line.comments_after(leaf): result.append(comment_after, preformatted=True) bracket_split_succeeded_or_raise(head, body, tail) for result in (head, body, tail): if result: yield result def right_hand_split( line: Line, py36: bool = False, 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. """ head = Line(depth=line.depth) body = Line(depth=line.depth + 1, inside_brackets=True) tail = Line(depth=line.depth) tail_leaves: List[Leaf] = [] body_leaves: List[Leaf] = [] head_leaves: List[Leaf] = [] current_leaves = tail_leaves opening_bracket = None 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 tail_leaves.reverse() body_leaves.reverse() head_leaves.reverse() # Since body is a new indent level, remove spurious leading whitespace. if body_leaves: normalize_prefix(body_leaves[0], inside_brackets=True) elif not head_leaves: # No `head` and no `body` means the split failed. `tail` has all content. raise CannotSplit("No brackets found") # Build the new lines. for result, leaves in (head, head_leaves), (body, body_leaves), (tail, tail_leaves): for leaf in leaves: result.append(leaf, preformatted=True) for comment_after in line.comments_after(leaf): result.append(comment_after, preformatted=True) bracket_split_succeeded_or_raise(head, body, tail) assert opening_bracket and closing_bracket if ( # the opening bracket is an optional paren 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 # there are no delimiters or standalone comments in the body and not body.bracket_tracker.delimiters and not line.contains_standalone_comments(0) # and 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 ): omit = {id(closing_bracket), *omit} try: yield from right_hand_split(line, py36=py36, omit=omit) return except CannotSplit: pass 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 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, py36: bool = False) -> Iterator[Line]: for l in split_func(line, py36): normalize_prefix(l.leaves[0], inside_brackets=True) yield l return split_wrapper @dont_increase_indentation def delimiter_split(line: Line, py36: bool = False) -> Iterator[Line]: """Split according to delimiters of the highest priority. If `py36` is True, the split will add trailing commas also in function signatures that contain `*` and `**`. """ try: last_leaf = line.leaves[-1] except IndexError: raise CannotSplit("Line empty") delimiters = line.bracket_tracker.delimiters try: delimiter_priority = line.bracket_tracker.max_delimiter_priority( exclude={id(last_leaf)} ) except ValueError: raise CannotSplit("No delimiters found") 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 as ve: 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 and is_vararg(leaf, within=VARARGS_PARENTS) ): trailing_comma_safe = trailing_comma_safe and py36 leaf_priority = 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, py36: bool = False) -> 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 as ve: 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 explode_split( line: Line, py36: bool = False, omit: Collection[LeafID] = () ) -> Iterator[Line]: """Split by rightmost bracket and immediately split contents by a delimiter.""" new_lines = list(right_hand_split(line, py36, omit)) if len(new_lines) != 3: yield from new_lines return yield new_lines[0] try: yield from delimiter_split(new_lines[1], py36) except CannotSplit: yield new_lines[1] yield new_lines[2] 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 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_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 quotes new_body = sub_twice(escaped_new_quote, rf"\1\2{new_quote}", body) if body != new_body: # Consider the string without unnecessary quotes 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 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_invisible_parens(node: Node, parens_after: Set[str]) -> None: """Make existing optional parentheses invisible or create new ones. Standardizes on visible parentheses for single-element tuples, and keeps existing visible parentheses for other tuples and generator expressions. """ check_lpar = False for child in list(node.children): if check_lpar: if child.type == syms.atom: maybe_make_parens_invisible_in_atom(child) elif is_one_tuple(child): # wrap child in visible parentheses lpar = Leaf(token.LPAR, "(") rpar = Leaf(token.RPAR, ")") index = child.remove() or 0 node.insert_child(index, Node(syms.atom, [lpar, child, rpar])) else: # wrap child in invisible parentheses lpar = Leaf(token.LPAR, "") rpar = Leaf(token.RPAR, "") index = child.remove() or 0 node.insert_child(index, Node(syms.atom, [lpar, child, rpar])) check_lpar = isinstance(child, Leaf) and child.value in parens_after def maybe_make_parens_invisible_in_atom(node: LN) -> bool: """If it's safe, make the parens in the atom `node` invisible, recusively.""" if ( node.type != syms.atom or is_empty_tuple(node) or is_one_tuple(node) 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: # make parentheses invisible first.value = "" # type: ignore last.value = "" # type: ignore if len(node.children) > 1: maybe_make_parens_invisible_in_atom(node.children[1]) return True return False def is_empty_tuple(node: LN) -> bool: """Return True if `node` holds an empty tuple.""" return ( node.type == syms.atom and len(node.children) == 2 and node.children[0].type == token.LPAR and node.children[1].type == token.RPAR ) def is_one_tuple(node: LN) -> bool: """Return True if `node` holds a tuple with one element, with or without parens.""" if node.type == syms.atom: if len(node.children) != 3: return False lpar, gexp, rpar = node.children if not ( lpar.type == token.LPAR and gexp.type == syms.testlist_gexp and rpar.type == token.RPAR ): 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_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 COLLECTION_LIBERALS_PARENTS, it applies to right hand-side extended iterable unpacking (PEP 3132) and additional unpacking generalizations (PEP 448). """ if leaf.type not in STARS 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 max_delimiter_priority_in_atom(node: LN) -> int: """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_invible_parens` and :func:`visit_import_from`). """ if leaf.type == token.LPAR: leaf.value = "(" elif leaf.type == token.RPAR: leaf.value = ")" def is_python36(node: Node) -> bool: """Return True if the current file is using Python 3.6+ features. Currently looking for: - f-strings; and - trailing commas after * or ** in function signatures. """ 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"}: return True elif ( n.type == syms.typedargslist and n.children and n.children[-1].type == token.COMMA ): for ch in n.children: if ch.type in STARS: return True return False PYTHON_EXTENSIONS = {".py"} BLACKLISTED_DIRECTORIES = { "build", "buck-out", "dist", "_build", ".git", ".hg", ".mypy_cache", ".tox", ".venv" } 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: continue yield from gen_python_files_in_dir(child) elif child.suffix in PYTHON_EXTENSIONS: yield child @dataclass class Report: """Provides a reformatting counter. Can be rendered with `str(report)`.""" check: bool = False quiet: 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 not self.quiet: out(f"{reformatted} {src}") self.change_count += 1 else: if not self.quiet: 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 @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 returncodes 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 assert_equivalent(src: str, dst: str) -> None: """Raise AssertionError if `src` and `dst` aren't equivalent.""" import ast import traceback def _v(node: ast.AST, depth: int = 0) -> Iterator[str]: """Simple visitor generating strings to compare ASTs by content.""" yield f"{' ' * depth}{node.__class__.__name__}(" for field in sorted(node._fields): try: value = getattr(node, field) except AttributeError: continue yield f"{' ' * (depth+1)}{field}=" if isinstance(value, list): for item in value: if isinstance(item, ast.AST): yield from _v(item, depth + 2) elif isinstance(value, ast.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 = ast.parse(src) except Exception as exc: 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) 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/ambv/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/ambv/black/issues. " f"This diff might be helpful: {log}" ) from None def assert_stable(src: str, dst: str, line_length: int) -> None: """Raise AssertionError if `dst` reformats differently the second time.""" newdst = format_str(dst, line_length=line_length) 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/ambv/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.""" import tempfile 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 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: List[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: BaseEventLoop) -> None: """Cancel all pending tasks on `loop`, wait for them, and close the loop.""" try: # This part is borrowed from asyncio/runners.py in Python 3.7b2. to_cancel = [task for task in asyncio.Task.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)) CACHE_DIR = Path(user_cache_dir("black", version=__version__)) def get_cache_file(line_length: int) -> Path: return CACHE_DIR / f"cache.{line_length}.pickle" def read_cache(line_length: int) -> 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(line_length) 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[List[Path], List[Path]]: """Split a list of paths into two. The first list contains paths of files that modified on disk or are not in the cache. The other list contains paths to non-modified files. """ todo, done = [], [] for src in sources: src = src.resolve() if cache.get(src) != get_cache_info(src): todo.append(src) else: done.append(src) return todo, done def write_cache(cache: Cache, sources: List[Path], line_length: int) -> None: """Update the cache file.""" cache_file = get_cache_file(line_length) try: if not CACHE_DIR.exists(): CACHE_DIR.mkdir(parents=True) new_cache = {**cache, **{src.resolve(): get_cache_info(src) for src in sources}} with cache_file.open("wb") as fobj: pickle.dump(new_cache, fobj, protocol=pickle.HIGHEST_PROTOCOL) except OSError: pass if __name__ == "__main__": main()