diff --git a/contrib/examples/fix.hgrc b/contrib/examples/fix.hgrc --- a/contrib/examples/fix.hgrc +++ b/contrib/examples/fix.hgrc @@ -5,6 +5,11 @@ rustfmt:command = rustfmt {rootpath} rustfmt:pattern = set:**.rs -# We use black, but currently with https://github.com/psf/black/pull/826 applied. -# black:command = black --skip-string-normalization +# We use black, but currently with +# https://github.com/psf/black/pull/826 applied. For now +# contrib/grey.py is our fork of black. You need to pip install +# git+https://github.com/python/black/@d9e71a75ccfefa3d9156a64c03313a0d4ad981e5 +# to have the dependencies for grey. +# +# black:command = python3.7 contrib/grey.py --skip-string-normalization # black:pattern = set:**.py - hgext/fsmonitor/pywatchman/** - mercurial/thirdparty/** - "contrib/python-zstandard/**" diff --git a/contrib/grey.py b/contrib/grey.py new file mode 100644 --- /dev/null +++ b/contrib/grey.py @@ -0,0 +1,4093 @@ +import ast +import asyncio +from concurrent.futures import Executor, ProcessPoolExecutor +from contextlib import contextmanager +from datetime import datetime +from enum import Enum +from functools import lru_cache, partial, wraps +import io +import itertools +import logging +from multiprocessing import Manager, freeze_support +import os +from pathlib import Path +import pickle +import re +import signal +import sys +import tempfile +import tokenize +import traceback +from typing import ( + Any, + Callable, + Collection, + Dict, + Generator, + Generic, + Iterable, + Iterator, + List, + Optional, + Pattern, + Sequence, + Set, + Tuple, + TypeVar, + Union, + cast, +) + +from appdirs import user_cache_dir +from attr import dataclass, evolve, Factory +import click +import toml +from typed_ast import ast3, ast27 + +# lib2to3 fork +from blib2to3.pytree import Node, Leaf, type_repr +from blib2to3 import pygram, pytree +from blib2to3.pgen2 import driver, token +from blib2to3.pgen2.grammar import Grammar +from blib2to3.pgen2.parse import ParseError + +__version__ = '19.3b1.dev95+gdc1add6.d20191005' + +DEFAULT_LINE_LENGTH = 88 +DEFAULT_EXCLUDES = ( + r"/(\.eggs|\.git|\.hg|\.mypy_cache|\.nox|\.tox|\.venv|_build|buck-out|build|dist)/" +) +DEFAULT_INCLUDES = r"\.pyi?$" +CACHE_DIR = Path(user_cache_dir("black", version=__version__)) + + +# types +FileContent = str +Encoding = str +NewLine = str +Depth = int +NodeType = int +LeafID = int +Priority = int +Index = int +LN = Union[Leaf, Node] +SplitFunc = Callable[["Line", Collection["Feature"]], Iterator["Line"]] +Timestamp = float +FileSize = int +CacheInfo = Tuple[Timestamp, FileSize] +Cache = Dict[Path, CacheInfo] +out = partial(click.secho, bold=True, err=True) +err = partial(click.secho, fg="red", err=True) + +pygram.initialize(CACHE_DIR) +syms = pygram.python_symbols + + +class NothingChanged(UserWarning): + """Raised when reformatted code is the same as source.""" + + +class CannotSplit(Exception): + """A readable split that fits the allotted line length is impossible.""" + + +class InvalidInput(ValueError): + """Raised when input source code fails all parse attempts.""" + + +class WriteBack(Enum): + NO = 0 + YES = 1 + DIFF = 2 + CHECK = 3 + + @classmethod + def from_configuration(cls, *, check: bool, diff: bool) -> "WriteBack": + if check and not diff: + return cls.CHECK + + return cls.DIFF if diff else cls.YES + + +class Changed(Enum): + NO = 0 + CACHED = 1 + YES = 2 + + +class TargetVersion(Enum): + PY27 = 2 + PY33 = 3 + PY34 = 4 + PY35 = 5 + PY36 = 6 + PY37 = 7 + PY38 = 8 + + def is_python2(self) -> bool: + return self is TargetVersion.PY27 + + +PY36_VERSIONS = {TargetVersion.PY36, TargetVersion.PY37, TargetVersion.PY38} + + +class Feature(Enum): + # All string literals are unicode + UNICODE_LITERALS = 1 + F_STRINGS = 2 + NUMERIC_UNDERSCORES = 3 + TRAILING_COMMA_IN_CALL = 4 + TRAILING_COMMA_IN_DEF = 5 + # The following two feature-flags are mutually exclusive, and exactly one should be + # set for every version of python. + ASYNC_IDENTIFIERS = 6 + ASYNC_KEYWORDS = 7 + ASSIGNMENT_EXPRESSIONS = 8 + POS_ONLY_ARGUMENTS = 9 + + +VERSION_TO_FEATURES: Dict[TargetVersion, Set[Feature]] = { + TargetVersion.PY27: {Feature.ASYNC_IDENTIFIERS}, + TargetVersion.PY33: {Feature.UNICODE_LITERALS, Feature.ASYNC_IDENTIFIERS}, + TargetVersion.PY34: {Feature.UNICODE_LITERALS, Feature.ASYNC_IDENTIFIERS}, + TargetVersion.PY35: { + Feature.UNICODE_LITERALS, + Feature.TRAILING_COMMA_IN_CALL, + Feature.ASYNC_IDENTIFIERS, + }, + TargetVersion.PY36: { + Feature.UNICODE_LITERALS, + Feature.F_STRINGS, + Feature.NUMERIC_UNDERSCORES, + Feature.TRAILING_COMMA_IN_CALL, + Feature.TRAILING_COMMA_IN_DEF, + Feature.ASYNC_IDENTIFIERS, + }, + TargetVersion.PY37: { + Feature.UNICODE_LITERALS, + Feature.F_STRINGS, + Feature.NUMERIC_UNDERSCORES, + Feature.TRAILING_COMMA_IN_CALL, + Feature.TRAILING_COMMA_IN_DEF, + Feature.ASYNC_KEYWORDS, + }, + TargetVersion.PY38: { + Feature.UNICODE_LITERALS, + Feature.F_STRINGS, + Feature.NUMERIC_UNDERSCORES, + Feature.TRAILING_COMMA_IN_CALL, + Feature.TRAILING_COMMA_IN_DEF, + Feature.ASYNC_KEYWORDS, + Feature.ASSIGNMENT_EXPRESSIONS, + Feature.POS_ONLY_ARGUMENTS, + }, +} + + +@dataclass +class FileMode: + target_versions: Set[TargetVersion] = Factory(set) + line_length: int = DEFAULT_LINE_LENGTH + string_normalization: bool = True + is_pyi: bool = False + + def get_cache_key(self) -> str: + if self.target_versions: + version_str = ",".join( + str(version.value) + for version in sorted(self.target_versions, key=lambda v: v.value) + ) + else: + version_str = "-" + parts = [ + version_str, + str(self.line_length), + str(int(self.string_normalization)), + str(int(self.is_pyi)), + ] + return ".".join(parts) + + +def supports_feature(target_versions: Set[TargetVersion], feature: Feature) -> bool: + return all(feature in VERSION_TO_FEATURES[version] for version in target_versions) + + +def read_pyproject_toml( + ctx: click.Context, param: click.Parameter, value: Union[str, int, bool, None] +) -> Optional[str]: + """Inject Black configuration from "pyproject.toml" into defaults in `ctx`. + + Returns the path to a successfully found and read configuration file, None + otherwise. + """ + assert not isinstance(value, (int, bool)), "Invalid parameter type passed" + if not value: + root = find_project_root(ctx.params.get("src", ())) + path = root / "pyproject.toml" + if path.is_file(): + value = str(path) + else: + return None + + try: + pyproject_toml = toml.load(value) + config = pyproject_toml.get("tool", {}).get("black", {}) + except (toml.TomlDecodeError, OSError) as e: + raise click.FileError( + filename=value, hint=f"Error reading configuration file: {e}" + ) + + if not config: + return None + + if ctx.default_map is None: + ctx.default_map = {} + ctx.default_map.update( # type: ignore # bad types in .pyi + {k.replace("--", "").replace("-", "_"): v for k, v in config.items()} + ) + return value + + +@click.command(context_settings=dict(help_option_names=["-h", "--help"])) +@click.option("-c", "--code", type=str, help="Format the code passed in as a string.") +@click.option( + "-l", + "--line-length", + type=int, + default=DEFAULT_LINE_LENGTH, + help="How many characters per line to allow.", + show_default=True, +) +@click.option( + "-t", + "--target-version", + type=click.Choice([v.name.lower() for v in TargetVersion]), + callback=lambda c, p, v: [TargetVersion[val.upper()] for val in v], + multiple=True, + help=( + "Python versions that should be supported by Black's output. [default: " + "per-file auto-detection]" + ), +) +@click.option( + "--py36", + is_flag=True, + help=( + "Allow using Python 3.6-only syntax on all input files. This will put " + "trailing commas in function signatures and calls also after *args and " + "**kwargs. Deprecated; use --target-version instead. " + "[default: per-file auto-detection]" + ), +) +@click.option( + "--pyi", + is_flag=True, + help=( + "Format all input files like typing stubs regardless of file extension " + "(useful when piping source on standard input)." + ), +) +@click.option( + "-S", + "--skip-string-normalization", + is_flag=True, + help="Don't normalize string quotes or prefixes.", +) +@click.option( + "--check", + is_flag=True, + help=( + "Don't write the files back, just return the status. Return code 0 " + "means nothing would change. Return code 1 means some files would be " + "reformatted. Return code 123 means there was an internal error." + ), +) +@click.option( + "--diff", + is_flag=True, + help="Don't write the files back, just output a diff for each file on stdout.", +) +@click.option( + "--fast/--safe", + is_flag=True, + help="If --fast given, skip temporary sanity checks. [default: --safe]", +) +@click.option( + "--include", + type=str, + default=DEFAULT_INCLUDES, + help=( + "A regular expression that matches files and directories that should be " + "included on recursive searches. An empty value means all files are " + "included regardless of the name. Use forward slashes for directories on " + "all platforms (Windows, too). Exclusions are calculated first, inclusions " + "later." + ), + show_default=True, +) +@click.option( + "--exclude", + type=str, + default=DEFAULT_EXCLUDES, + help=( + "A regular expression that matches files and directories that should be " + "excluded on recursive searches. An empty value means no paths are excluded. " + "Use forward slashes for directories on all platforms (Windows, too). " + "Exclusions are calculated first, inclusions later." + ), + show_default=True, +) +@click.option( + "-q", + "--quiet", + is_flag=True, + help=( + "Don't emit non-error messages to stderr. Errors are still emitted; " + "silence those with 2>/dev/null." + ), +) +@click.option( + "-v", + "--verbose", + is_flag=True, + help=( + "Also emit messages to stderr about files that were not changed or were " + "ignored due to --exclude=." + ), +) +@click.version_option(version=__version__) +@click.argument( + "src", + nargs=-1, + type=click.Path( + exists=True, file_okay=True, dir_okay=True, readable=True, allow_dash=True + ), + is_eager=True, +) +@click.option( + "--config", + type=click.Path( + exists=False, file_okay=True, dir_okay=False, readable=True, allow_dash=False + ), + is_eager=True, + callback=read_pyproject_toml, + help="Read configuration from PATH.", +) +@click.pass_context +def main( + ctx: click.Context, + code: Optional[str], + line_length: int, + target_version: List[TargetVersion], + check: bool, + diff: bool, + fast: bool, + pyi: bool, + py36: bool, + skip_string_normalization: bool, + quiet: bool, + verbose: bool, + include: str, + exclude: str, + src: Tuple[str], + config: Optional[str], +) -> None: + """The uncompromising code formatter.""" + write_back = WriteBack.from_configuration(check=check, diff=diff) + if target_version: + if py36: + err(f"Cannot use both --target-version and --py36") + ctx.exit(2) + else: + versions = set(target_version) + elif py36: + err( + "--py36 is deprecated and will be removed in a future version. " + "Use --target-version py36 instead." + ) + versions = PY36_VERSIONS + else: + # We'll autodetect later. + versions = set() + mode = FileMode( + target_versions=versions, + line_length=line_length, + is_pyi=pyi, + string_normalization=not skip_string_normalization, + ) + if config and verbose: + out(f"Using configuration from {config}.", bold=False, fg="blue") + if code is not None: + print(format_str(code, mode=mode)) + ctx.exit(0) + try: + include_regex = re_compile_maybe_verbose(include) + except re.error: + err(f"Invalid regular expression for include given: {include!r}") + ctx.exit(2) + try: + exclude_regex = re_compile_maybe_verbose(exclude) + except re.error: + err(f"Invalid regular expression for exclude given: {exclude!r}") + ctx.exit(2) + report = Report(check=check, quiet=quiet, verbose=verbose) + root = find_project_root(src) + sources: Set[Path] = set() + path_empty(src, quiet, verbose, ctx) + for s in src: + p = Path(s) + if p.is_dir(): + sources.update( + gen_python_files_in_dir(p, root, include_regex, exclude_regex, report) + ) + elif p.is_file() or s == "-": + # if a file was explicitly given, we don't care about its extension + sources.add(p) + else: + err(f"invalid path: {s}") + if len(sources) == 0: + if verbose or not quiet: + out("No Python files are present to be formatted. Nothing to do 😴") + ctx.exit(0) + + if len(sources) == 1: + reformat_one( + src=sources.pop(), + fast=fast, + write_back=write_back, + mode=mode, + report=report, + ) + else: + reformat_many( + sources=sources, fast=fast, write_back=write_back, mode=mode, report=report + ) + + if verbose or not quiet: + out("Oh no! 💥 💔 💥" if report.return_code else "All done! ✨ 🍰 ✨") + click.secho(str(report), err=True) + ctx.exit(report.return_code) + + +def path_empty(src: Tuple[str], quiet: bool, verbose: bool, ctx: click.Context) -> None: + """ + Exit if there is no `src` provided for formatting + """ + if not src: + if verbose or not quiet: + out("No Path provided. Nothing to do 😴") + ctx.exit(0) + + +def reformat_one( + src: Path, fast: bool, write_back: WriteBack, mode: FileMode, report: "Report" +) -> None: + """Reformat a single file under `src` without spawning child processes. + + `fast`, `write_back`, and `mode` options are passed to + :func:`format_file_in_place` or :func:`format_stdin_to_stdout`. + """ + try: + changed = Changed.NO + if not src.is_file() and str(src) == "-": + if format_stdin_to_stdout(fast=fast, write_back=write_back, mode=mode): + changed = Changed.YES + else: + cache: Cache = {} + if write_back != WriteBack.DIFF: + cache = read_cache(mode) + res_src = src.resolve() + if res_src in cache and cache[res_src] == get_cache_info(res_src): + changed = Changed.CACHED + if changed is not Changed.CACHED and format_file_in_place( + src, fast=fast, write_back=write_back, mode=mode + ): + changed = Changed.YES + if (write_back is WriteBack.YES and changed is not Changed.CACHED) or ( + write_back is WriteBack.CHECK and changed is Changed.NO + ): + write_cache(cache, [src], mode) + report.done(src, changed) + except Exception as exc: + report.failed(src, str(exc)) + + +def reformat_many( + sources: Set[Path], + fast: bool, + write_back: WriteBack, + mode: FileMode, + report: "Report", +) -> None: + """Reformat multiple files using a ProcessPoolExecutor.""" + loop = asyncio.get_event_loop() + worker_count = os.cpu_count() + if sys.platform == "win32": + # Work around https://bugs.python.org/issue26903 + worker_count = min(worker_count, 61) + executor = ProcessPoolExecutor(max_workers=worker_count) + try: + loop.run_until_complete( + schedule_formatting( + sources=sources, + fast=fast, + write_back=write_back, + mode=mode, + report=report, + loop=loop, + executor=executor, + ) + ) + finally: + shutdown(loop) + executor.shutdown() + + +async def schedule_formatting( + sources: Set[Path], + fast: bool, + write_back: WriteBack, + mode: FileMode, + report: "Report", + loop: asyncio.AbstractEventLoop, + executor: Executor, +) -> None: + """Run formatting of `sources` in parallel using the provided `executor`. + + (Use ProcessPoolExecutors for actual parallelism.) + + `write_back`, `fast`, and `mode` options are passed to + :func:`format_file_in_place`. + """ + cache: Cache = {} + if write_back != WriteBack.DIFF: + cache = read_cache(mode) + sources, cached = filter_cached(cache, sources) + for src in sorted(cached): + report.done(src, Changed.CACHED) + if not sources: + return + + cancelled = [] + sources_to_cache = [] + lock = None + if write_back == WriteBack.DIFF: + # For diff output, we need locks to ensure we don't interleave output + # from different processes. + manager = Manager() + lock = manager.Lock() + tasks = { + asyncio.ensure_future( + loop.run_in_executor( + executor, format_file_in_place, src, fast, mode, write_back, lock + ) + ): src + for src in sorted(sources) + } + pending: Iterable[asyncio.Future] = tasks.keys() + try: + loop.add_signal_handler(signal.SIGINT, cancel, pending) + loop.add_signal_handler(signal.SIGTERM, cancel, pending) + except NotImplementedError: + # There are no good alternatives for these on Windows. + pass + while pending: + done, _ = await asyncio.wait(pending, return_when=asyncio.FIRST_COMPLETED) + for task in done: + src = tasks.pop(task) + if task.cancelled(): + cancelled.append(task) + elif task.exception(): + report.failed(src, str(task.exception())) + else: + changed = Changed.YES if task.result() else Changed.NO + # If the file was written back or was successfully checked as + # well-formatted, store this information in the cache. + if write_back is WriteBack.YES or ( + write_back is WriteBack.CHECK and changed is Changed.NO + ): + sources_to_cache.append(src) + report.done(src, changed) + if cancelled: + await asyncio.gather(*cancelled, loop=loop, return_exceptions=True) + if sources_to_cache: + write_cache(cache, sources_to_cache, mode) + + +def format_file_in_place( + src: Path, + fast: bool, + mode: FileMode, + write_back: WriteBack = WriteBack.NO, + lock: Any = None, # multiprocessing.Manager().Lock() is some crazy proxy +) -> bool: + """Format file under `src` path. Return True if changed. + + If `write_back` is DIFF, write a diff to stdout. If it is YES, write reformatted + code to the file. + `mode` and `fast` options are passed to :func:`format_file_contents`. + """ + if src.suffix == ".pyi": + mode = evolve(mode, is_pyi=True) + + then = datetime.utcfromtimestamp(src.stat().st_mtime) + with open(src, "rb") as buf: + src_contents, encoding, newline = decode_bytes(buf.read()) + try: + dst_contents = format_file_contents(src_contents, fast=fast, mode=mode) + except NothingChanged: + return False + + if write_back == write_back.YES: + with open(src, "w", encoding=encoding, newline=newline) as f: + f.write(dst_contents) + elif write_back == write_back.DIFF: + now = datetime.utcnow() + src_name = f"{src}\t{then} +0000" + dst_name = f"{src}\t{now} +0000" + diff_contents = diff(src_contents, dst_contents, src_name, dst_name) + + with lock or nullcontext(): + f = io.TextIOWrapper( + sys.stdout.buffer, + encoding=encoding, + newline=newline, + write_through=True, + ) + f.write(diff_contents) + f.detach() + + return True + + +def format_stdin_to_stdout( + fast: bool, *, write_back: WriteBack = WriteBack.NO, mode: FileMode +) -> bool: + """Format file on stdin. Return True if changed. + + If `write_back` is YES, write reformatted code back to stdout. If it is DIFF, + write a diff to stdout. The `mode` argument is passed to + :func:`format_file_contents`. + """ + then = datetime.utcnow() + src, encoding, newline = decode_bytes(sys.stdin.buffer.read()) + dst = src + try: + dst = format_file_contents(src, fast=fast, mode=mode) + return True + + except NothingChanged: + return False + + finally: + f = io.TextIOWrapper( + sys.stdout.buffer, encoding=encoding, newline=newline, write_through=True + ) + if write_back == WriteBack.YES: + f.write(dst) + elif write_back == WriteBack.DIFF: + now = datetime.utcnow() + src_name = f"STDIN\t{then} +0000" + dst_name = f"STDOUT\t{now} +0000" + f.write(diff(src, dst, src_name, dst_name)) + f.detach() + + +def format_file_contents( + src_contents: str, *, fast: bool, mode: FileMode +) -> FileContent: + """Reformat contents a file and return new contents. + + If `fast` is False, additionally confirm that the reformatted code is + valid by calling :func:`assert_equivalent` and :func:`assert_stable` on it. + `mode` is passed to :func:`format_str`. + """ + if src_contents.strip() == "": + raise NothingChanged + + dst_contents = format_str(src_contents, mode=mode) + if src_contents == dst_contents: + raise NothingChanged + + if not fast: + assert_equivalent(src_contents, dst_contents) + assert_stable(src_contents, dst_contents, mode=mode) + return dst_contents + + +def format_str(src_contents: str, *, mode: FileMode) -> FileContent: + """Reformat a string and return new contents. + + `mode` determines formatting options, such as how many characters per line are + allowed. + """ + src_node = lib2to3_parse(src_contents.lstrip(), mode.target_versions) + dst_contents = [] + future_imports = get_future_imports(src_node) + if mode.target_versions: + versions = mode.target_versions + else: + versions = detect_target_versions(src_node) + normalize_fmt_off(src_node) + lines = LineGenerator( + remove_u_prefix="unicode_literals" in future_imports + or supports_feature(versions, Feature.UNICODE_LITERALS), + is_pyi=mode.is_pyi, + normalize_strings=mode.string_normalization, + ) + elt = EmptyLineTracker(is_pyi=mode.is_pyi) + empty_line = Line() + after = 0 + split_line_features = { + feature + for feature in {Feature.TRAILING_COMMA_IN_CALL, Feature.TRAILING_COMMA_IN_DEF} + if supports_feature(versions, feature) + } + for current_line in lines.visit(src_node): + for _ in range(after): + dst_contents.append(str(empty_line)) + before, after = elt.maybe_empty_lines(current_line) + for _ in range(before): + dst_contents.append(str(empty_line)) + for line in split_line( + current_line, line_length=mode.line_length, features=split_line_features + ): + dst_contents.append(str(line)) + return "".join(dst_contents) + + +def decode_bytes(src: bytes) -> Tuple[FileContent, Encoding, NewLine]: + """Return a tuple of (decoded_contents, encoding, newline). + + `newline` is either CRLF or LF but `decoded_contents` is decoded with + universal newlines (i.e. only contains LF). + """ + srcbuf = io.BytesIO(src) + encoding, lines = tokenize.detect_encoding(srcbuf.readline) + if not lines: + return "", encoding, "\n" + + newline = "\r\n" if b"\r\n" == lines[0][-2:] else "\n" + srcbuf.seek(0) + with io.TextIOWrapper(srcbuf, encoding) as tiow: + return tiow.read(), encoding, newline + + +def get_grammars(target_versions: Set[TargetVersion]) -> List[Grammar]: + if not target_versions: + # No target_version specified, so try all grammars. + return [ + # Python 3.7+ + pygram.python_grammar_no_print_statement_no_exec_statement_async_keywords, + # Python 3.0-3.6 + pygram.python_grammar_no_print_statement_no_exec_statement, + # Python 2.7 with future print_function import + pygram.python_grammar_no_print_statement, + # Python 2.7 + pygram.python_grammar, + ] + elif all(version.is_python2() for version in target_versions): + # Python 2-only code, so try Python 2 grammars. + return [ + # Python 2.7 with future print_function import + pygram.python_grammar_no_print_statement, + # Python 2.7 + pygram.python_grammar, + ] + else: + # Python 3-compatible code, so only try Python 3 grammar. + grammars = [] + # If we have to parse both, try to parse async as a keyword first + if not supports_feature(target_versions, Feature.ASYNC_IDENTIFIERS): + # Python 3.7+ + grammars.append( + pygram.python_grammar_no_print_statement_no_exec_statement_async_keywords # noqa: B950 + ) + if not supports_feature(target_versions, Feature.ASYNC_KEYWORDS): + # Python 3.0-3.6 + grammars.append(pygram.python_grammar_no_print_statement_no_exec_statement) + # At least one of the above branches must have been taken, because every Python + # version has exactly one of the two 'ASYNC_*' flags + return grammars + + +def lib2to3_parse(src_txt: str, target_versions: Iterable[TargetVersion] = ()) -> Node: + """Given a string with source, return the lib2to3 Node.""" + if src_txt[-1:] != "\n": + src_txt += "\n" + + for grammar in get_grammars(set(target_versions)): + drv = driver.Driver(grammar, pytree.convert) + try: + result = drv.parse_string(src_txt, True) + break + + except ParseError as pe: + lineno, column = pe.context[1] + lines = src_txt.splitlines() + try: + faulty_line = lines[lineno - 1] + except IndexError: + faulty_line = "" + exc = InvalidInput(f"Cannot parse: {lineno}:{column}: {faulty_line}") + else: + raise exc from None + + if isinstance(result, Leaf): + result = Node(syms.file_input, [result]) + return result + + +def lib2to3_unparse(node: Node) -> str: + """Given a lib2to3 node, return its string representation.""" + code = str(node) + return code + + +T = TypeVar("T") + + +class Visitor(Generic[T]): + """Basic lib2to3 visitor that yields things of type `T` on `visit()`.""" + + def visit(self, node: LN) -> Iterator[T]: + """Main method to visit `node` and its children. + + It tries to find a `visit_*()` method for the given `node.type`, like + `visit_simple_stmt` for Node objects or `visit_INDENT` for Leaf objects. + If no dedicated `visit_*()` method is found, chooses `visit_default()` + instead. + + Then yields objects of type `T` from the selected visitor. + """ + if node.type < 256: + name = token.tok_name[node.type] + else: + name = type_repr(node.type) + yield from getattr(self, f"visit_{name}", self.visit_default)(node) + + def visit_default(self, node: LN) -> Iterator[T]: + """Default `visit_*()` implementation. Recurses to children of `node`.""" + if isinstance(node, Node): + for child in node.children: + yield from self.visit(child) + + +@dataclass +class DebugVisitor(Visitor[T]): + tree_depth: int = 0 + + def visit_default(self, node: LN) -> Iterator[T]: + indent = " " * (2 * self.tree_depth) + if isinstance(node, Node): + _type = type_repr(node.type) + out(f"{indent}{_type}", fg="yellow") + self.tree_depth += 1 + for child in node.children: + yield from self.visit(child) + + self.tree_depth -= 1 + out(f"{indent}/{_type}", fg="yellow", bold=False) + else: + _type = token.tok_name.get(node.type, str(node.type)) + out(f"{indent}{_type}", fg="blue", nl=False) + if node.prefix: + # We don't have to handle prefixes for `Node` objects since + # that delegates to the first child anyway. + out(f" {node.prefix!r}", fg="green", bold=False, nl=False) + out(f" {node.value!r}", fg="blue", bold=False) + + @classmethod + def show(cls, code: Union[str, Leaf, Node]) -> None: + """Pretty-print the lib2to3 AST of a given string of `code`. + + Convenience method for debugging. + """ + v: DebugVisitor[None] = DebugVisitor() + if isinstance(code, str): + code = lib2to3_parse(code) + list(v.visit(code)) + + +WHITESPACE = {token.DEDENT, token.INDENT, token.NEWLINE} +STATEMENT = { + syms.if_stmt, + syms.while_stmt, + syms.for_stmt, + syms.try_stmt, + syms.except_clause, + syms.with_stmt, + syms.funcdef, + syms.classdef, +} +STANDALONE_COMMENT = 153 +token.tok_name[STANDALONE_COMMENT] = "STANDALONE_COMMENT" +LOGIC_OPERATORS = {"and", "or"} +COMPARATORS = { + token.LESS, + token.GREATER, + token.EQEQUAL, + token.NOTEQUAL, + token.LESSEQUAL, + token.GREATEREQUAL, +} +MATH_OPERATORS = { + token.VBAR, + token.CIRCUMFLEX, + token.AMPER, + token.LEFTSHIFT, + token.RIGHTSHIFT, + token.PLUS, + token.MINUS, + token.STAR, + token.SLASH, + token.DOUBLESLASH, + token.PERCENT, + token.AT, + token.TILDE, + token.DOUBLESTAR, +} +STARS = {token.STAR, token.DOUBLESTAR} +VARARGS_SPECIALS = STARS | {token.SLASH} +VARARGS_PARENTS = { + syms.arglist, + syms.argument, # double star in arglist + syms.trailer, # single argument to call + syms.typedargslist, + syms.varargslist, # lambdas +} +UNPACKING_PARENTS = { + syms.atom, # single element of a list or set literal + syms.dictsetmaker, + syms.listmaker, + syms.testlist_gexp, + syms.testlist_star_expr, +} +TEST_DESCENDANTS = { + syms.test, + syms.lambdef, + syms.or_test, + syms.and_test, + syms.not_test, + syms.comparison, + syms.star_expr, + syms.expr, + syms.xor_expr, + syms.and_expr, + syms.shift_expr, + syms.arith_expr, + syms.trailer, + syms.term, + syms.power, +} +ASSIGNMENTS = { + "=", + "+=", + "-=", + "*=", + "@=", + "/=", + "%=", + "&=", + "|=", + "^=", + "<<=", + ">>=", + "**=", + "//=", +} +COMPREHENSION_PRIORITY = 20 +COMMA_PRIORITY = 18 +TERNARY_PRIORITY = 16 +LOGIC_PRIORITY = 14 +STRING_PRIORITY = 12 +COMPARATOR_PRIORITY = 10 +MATH_PRIORITIES = { + token.VBAR: 9, + token.CIRCUMFLEX: 8, + token.AMPER: 7, + token.LEFTSHIFT: 6, + token.RIGHTSHIFT: 6, + token.PLUS: 5, + token.MINUS: 5, + token.STAR: 4, + token.SLASH: 4, + token.DOUBLESLASH: 4, + token.PERCENT: 4, + token.AT: 4, + token.TILDE: 3, + token.DOUBLESTAR: 2, +} +DOT_PRIORITY = 1 + + +@dataclass +class BracketTracker: + """Keeps track of brackets on a line.""" + + depth: int = 0 + bracket_match: Dict[Tuple[Depth, NodeType], Leaf] = Factory(dict) + delimiters: Dict[LeafID, Priority] = Factory(dict) + previous: Optional[Leaf] = None + _for_loop_depths: List[int] = Factory(list) + _lambda_argument_depths: List[int] = Factory(list) + + def mark(self, leaf: Leaf) -> None: + """Mark `leaf` with bracket-related metadata. Keep track of delimiters. + + All leaves receive an int `bracket_depth` field that stores how deep + within brackets a given leaf is. 0 means there are no enclosing brackets + that started on this line. + + If a leaf is itself a closing bracket, it receives an `opening_bracket` + field that it forms a pair with. This is a one-directional link to + avoid reference cycles. + + If a leaf is a delimiter (a token on which Black can split the line if + needed) and it's on depth 0, its `id()` is stored in the tracker's + `delimiters` field. + """ + if leaf.type == token.COMMENT: + return + + self.maybe_decrement_after_for_loop_variable(leaf) + self.maybe_decrement_after_lambda_arguments(leaf) + if leaf.type in CLOSING_BRACKETS: + self.depth -= 1 + opening_bracket = self.bracket_match.pop((self.depth, leaf.type)) + leaf.opening_bracket = opening_bracket + leaf.bracket_depth = self.depth + if self.depth == 0: + delim = is_split_before_delimiter(leaf, self.previous) + if delim and self.previous is not None: + self.delimiters[id(self.previous)] = delim + else: + delim = is_split_after_delimiter(leaf, self.previous) + if delim: + self.delimiters[id(leaf)] = delim + if leaf.type in OPENING_BRACKETS: + self.bracket_match[self.depth, BRACKET[leaf.type]] = leaf + self.depth += 1 + self.previous = leaf + self.maybe_increment_lambda_arguments(leaf) + self.maybe_increment_for_loop_variable(leaf) + + def any_open_brackets(self) -> bool: + """Return True if there is an yet unmatched open bracket on the line.""" + return bool(self.bracket_match) + + def max_delimiter_priority(self, exclude: Iterable[LeafID] = ()) -> Priority: + """Return the highest priority of a delimiter found on the line. + + Values are consistent with what `is_split_*_delimiter()` return. + Raises ValueError on no delimiters. + """ + return max(v for k, v in self.delimiters.items() if k not in exclude) + + def delimiter_count_with_priority(self, priority: Priority = 0) -> int: + """Return the number of delimiters with the given `priority`. + + If no `priority` is passed, defaults to max priority on the line. + """ + if not self.delimiters: + return 0 + + priority = priority or self.max_delimiter_priority() + return sum(1 for p in self.delimiters.values() if p == priority) + + def maybe_increment_for_loop_variable(self, leaf: Leaf) -> bool: + """In a for loop, or comprehension, the variables are often unpacks. + + To avoid splitting on the comma in this situation, increase the depth of + tokens between `for` and `in`. + """ + if leaf.type == token.NAME and leaf.value == "for": + self.depth += 1 + self._for_loop_depths.append(self.depth) + return True + + return False + + def maybe_decrement_after_for_loop_variable(self, leaf: Leaf) -> bool: + """See `maybe_increment_for_loop_variable` above for explanation.""" + if ( + self._for_loop_depths + and self._for_loop_depths[-1] == self.depth + and leaf.type == token.NAME + and leaf.value == "in" + ): + self.depth -= 1 + self._for_loop_depths.pop() + return True + + return False + + def maybe_increment_lambda_arguments(self, leaf: Leaf) -> bool: + """In a lambda expression, there might be more than one argument. + + To avoid splitting on the comma in this situation, increase the depth of + tokens between `lambda` and `:`. + """ + if leaf.type == token.NAME and leaf.value == "lambda": + self.depth += 1 + self._lambda_argument_depths.append(self.depth) + return True + + return False + + def maybe_decrement_after_lambda_arguments(self, leaf: Leaf) -> bool: + """See `maybe_increment_lambda_arguments` above for explanation.""" + if ( + self._lambda_argument_depths + and self._lambda_argument_depths[-1] == self.depth + and leaf.type == token.COLON + ): + self.depth -= 1 + self._lambda_argument_depths.pop() + return True + + return False + + def get_open_lsqb(self) -> Optional[Leaf]: + """Return the most recent opening square bracket (if any).""" + return self.bracket_match.get((self.depth - 1, token.RSQB)) + + +@dataclass +class Line: + """Holds leaves and comments. Can be printed with `str(line)`.""" + + depth: int = 0 + leaves: List[Leaf] = Factory(list) + comments: Dict[LeafID, List[Leaf]] = Factory(dict) # keys ordered like `leaves` + bracket_tracker: BracketTracker = Factory(BracketTracker) + inside_brackets: bool = False + should_explode: bool = False + + def append(self, leaf: Leaf, preformatted: bool = False) -> None: + """Add a new `leaf` to the end of the line. + + Unless `preformatted` is True, the `leaf` will receive a new consistent + whitespace prefix and metadata applied by :class:`BracketTracker`. + Trailing commas are maybe removed, unpacked for loop variables are + demoted from being delimiters. + + Inline comments are put aside. + """ + has_value = leaf.type in BRACKETS or bool(leaf.value.strip()) + if not has_value: + return + + if token.COLON == leaf.type and self.is_class_paren_empty: + del self.leaves[-2:] + if self.leaves and not preformatted: + # Note: at this point leaf.prefix should be empty except for + # imports, for which we only preserve newlines. + leaf.prefix += whitespace( + leaf, complex_subscript=self.is_complex_subscript(leaf) + ) + if self.inside_brackets or not preformatted: + self.bracket_tracker.mark(leaf) + self.maybe_remove_trailing_comma(leaf) + if not self.append_comment(leaf): + self.leaves.append(leaf) + + def append_safe(self, leaf: Leaf, preformatted: bool = False) -> None: + """Like :func:`append()` but disallow invalid standalone comment structure. + + Raises ValueError when any `leaf` is appended after a standalone comment + or when a standalone comment is not the first leaf on the line. + """ + if self.bracket_tracker.depth == 0: + if self.is_comment: + raise ValueError("cannot append to standalone comments") + + if self.leaves and leaf.type == STANDALONE_COMMENT: + raise ValueError( + "cannot append standalone comments to a populated line" + ) + + self.append(leaf, preformatted=preformatted) + + @property + def is_comment(self) -> bool: + """Is this line a standalone comment?""" + return len(self.leaves) == 1 and self.leaves[0].type == STANDALONE_COMMENT + + @property + def is_decorator(self) -> bool: + """Is this line a decorator?""" + return bool(self) and self.leaves[0].type == token.AT + + @property + def is_import(self) -> bool: + """Is this an import line?""" + return bool(self) and is_import(self.leaves[0]) + + @property + def is_class(self) -> bool: + """Is this line a class definition?""" + return ( + bool(self) + and self.leaves[0].type == token.NAME + and self.leaves[0].value == "class" + ) + + @property + def is_stub_class(self) -> bool: + """Is this line a class definition with a body consisting only of "..."?""" + return self.is_class and self.leaves[-3:] == [ + Leaf(token.DOT, ".") for _ in range(3) + ] + + @property + def is_collection_with_optional_trailing_comma(self) -> bool: + """Is this line a collection literal with a trailing comma that's optional? + + Note that the trailing comma in a 1-tuple is not optional. + """ + if not self.leaves or len(self.leaves) < 4: + return False + # Look for and address a trailing colon. + if self.leaves[-1].type == token.COLON: + closer = self.leaves[-2] + close_index = -2 + else: + closer = self.leaves[-1] + close_index = -1 + if closer.type not in CLOSING_BRACKETS or self.inside_brackets: + return False + if closer.type == token.RPAR: + # Tuples require an extra check, because if there's only + # one element in the tuple removing the comma unmakes the + # tuple. + # + # We also check for parens before looking for the trailing + # comma because in some cases (eg assigning a dict + # literal) the literal gets wrapped in temporary parens + # during parsing. This case is covered by the + # collections.py test data. + opener = closer.opening_bracket + for _open_index, leaf in enumerate(self.leaves): + if leaf is opener: + break + else: + # Couldn't find the matching opening paren, play it safe. + return False + commas = 0 + comma_depth = self.leaves[close_index - 1].bracket_depth + for leaf in self.leaves[_open_index + 1 : close_index]: + if leaf.bracket_depth == comma_depth and leaf.type == token.COMMA: + commas += 1 + if commas > 1: + # We haven't looked yet for the trailing comma because + # we might also have caught noop parens. + return self.leaves[close_index - 1].type == token.COMMA + elif commas == 1: + return False # it's either a one-tuple or didn't have a trailing comma + if self.leaves[close_index - 1].type in CLOSING_BRACKETS: + close_index -= 1 + closer = self.leaves[close_index] + if closer.type == token.RPAR: + # TODO: this is a gut feeling. Will we ever see this? + return False + if self.leaves[close_index - 1].type != token.COMMA: + return False + return True + + @property + def is_def(self) -> bool: + """Is this a function definition? (Also returns True for async defs.)""" + try: + first_leaf = self.leaves[0] + except IndexError: + return False + + try: + second_leaf: Optional[Leaf] = self.leaves[1] + except IndexError: + second_leaf = None + return (first_leaf.type == token.NAME and first_leaf.value == "def") or ( + first_leaf.type == token.ASYNC + and second_leaf is not None + and second_leaf.type == token.NAME + and second_leaf.value == "def" + ) + + @property + def is_class_paren_empty(self) -> bool: + """Is this a class with no base classes but using parentheses? + + Those are unnecessary and should be removed. + """ + return ( + bool(self) + and len(self.leaves) == 4 + and self.is_class + and self.leaves[2].type == token.LPAR + and self.leaves[2].value == "(" + and self.leaves[3].type == token.RPAR + and self.leaves[3].value == ")" + ) + + @property + def is_triple_quoted_string(self) -> bool: + """Is the line a triple quoted string?""" + return ( + bool(self) + and self.leaves[0].type == token.STRING + and self.leaves[0].value.startswith(('"""', "'''")) + ) + + def contains_standalone_comments(self, depth_limit: int = sys.maxsize) -> bool: + """If so, needs to be split before emitting.""" + for leaf in self.leaves: + if leaf.type == STANDALONE_COMMENT: + if leaf.bracket_depth <= depth_limit: + return True + return False + + def contains_uncollapsable_type_comments(self) -> bool: + ignored_ids = set() + try: + last_leaf = self.leaves[-1] + ignored_ids.add(id(last_leaf)) + if last_leaf.type == token.COMMA or ( + last_leaf.type == token.RPAR and not last_leaf.value + ): + # When trailing commas or optional parens are inserted by Black for + # consistency, comments after the previous last element are not moved + # (they don't have to, rendering will still be correct). So we ignore + # trailing commas and invisible. + last_leaf = self.leaves[-2] + ignored_ids.add(id(last_leaf)) + except IndexError: + return False + + # A type comment is uncollapsable if it is attached to a leaf + # that isn't at the end of the line (since that could cause it + # to get associated to a different argument) or if there are + # comments before it (since that could cause it to get hidden + # behind a comment. + comment_seen = False + for leaf_id, comments in self.comments.items(): + for comment in comments: + if is_type_comment(comment): + if leaf_id not in ignored_ids or comment_seen: + return True + + comment_seen = True + + return False + + def contains_unsplittable_type_ignore(self) -> bool: + if not self.leaves: + return False + + # If a 'type: ignore' is attached to the end of a line, we + # can't split the line, because we can't know which of the + # subexpressions the ignore was meant to apply to. + # + # We only want this to apply to actual physical lines from the + # original source, though: we don't want the presence of a + # 'type: ignore' at the end of a multiline expression to + # justify pushing it all onto one line. Thus we + # (unfortunately) need to check the actual source lines and + # only report an unsplittable 'type: ignore' if this line was + # one line in the original code. + if self.leaves[0].lineno == self.leaves[-1].lineno: + for comment in self.comments.get(id(self.leaves[-1]), []): + if is_type_comment(comment, " ignore"): + return True + + return False + + def contains_multiline_strings(self) -> bool: + for leaf in self.leaves: + if is_multiline_string(leaf): + return True + + return False + + def maybe_remove_trailing_comma(self, closing: Leaf) -> bool: + """Remove trailing comma if there is one and it's safe.""" + if not (self.leaves and self.leaves[-1].type == token.COMMA): + return False + # We remove trailing commas only in the case of importing a + # single name from a module. + if not ( + self.leaves + and self.is_import + and len(self.leaves) > 4 + and self.leaves[-1].type == token.COMMA + and closing.type in CLOSING_BRACKETS + and self.leaves[-4].type == token.NAME + and ( + # regular `from foo import bar,` + self.leaves[-4].value == "import" + # `from foo import (bar as baz,) + or ( + len(self.leaves) > 6 + and self.leaves[-6].value == "import" + and self.leaves[-3].value == "as" + ) + # `from foo import bar as baz,` + or ( + len(self.leaves) > 5 + and self.leaves[-5].value == "import" + and self.leaves[-3].value == "as" + ) + ) + and closing.type == token.RPAR + ): + return False + + self.remove_trailing_comma() + return True + + def append_comment(self, comment: Leaf) -> bool: + """Add an inline or standalone comment to the line.""" + if ( + comment.type == STANDALONE_COMMENT + and self.bracket_tracker.any_open_brackets() + ): + comment.prefix = "" + return False + + if comment.type != token.COMMENT: + return False + + if not self.leaves: + comment.type = STANDALONE_COMMENT + comment.prefix = "" + return False + + last_leaf = self.leaves[-1] + if ( + last_leaf.type == token.RPAR + and not last_leaf.value + and last_leaf.parent + and len(list(last_leaf.parent.leaves())) <= 3 + and not is_type_comment(comment) + ): + # Comments on an optional parens wrapping a single leaf should belong to + # the wrapped node except if it's a type comment. Pinning the comment like + # this avoids unstable formatting caused by comment migration. + if len(self.leaves) < 2: + comment.type = STANDALONE_COMMENT + comment.prefix = "" + return False + last_leaf = self.leaves[-2] + self.comments.setdefault(id(last_leaf), []).append(comment) + return True + + def comments_after(self, leaf: Leaf) -> List[Leaf]: + """Generate comments that should appear directly after `leaf`.""" + return self.comments.get(id(leaf), []) + + def remove_trailing_comma(self) -> None: + """Remove the trailing comma and moves the comments attached to it.""" + trailing_comma = self.leaves.pop() + trailing_comma_comments = self.comments.pop(id(trailing_comma), []) + self.comments.setdefault(id(self.leaves[-1]), []).extend( + trailing_comma_comments + ) + + def is_complex_subscript(self, leaf: Leaf) -> bool: + """Return True iff `leaf` is part of a slice with non-trivial exprs.""" + open_lsqb = self.bracket_tracker.get_open_lsqb() + if open_lsqb is None: + return False + + subscript_start = open_lsqb.next_sibling + + if isinstance(subscript_start, Node): + if subscript_start.type == syms.listmaker: + return False + + if subscript_start.type == syms.subscriptlist: + subscript_start = child_towards(subscript_start, leaf) + return subscript_start is not None and any( + n.type in TEST_DESCENDANTS for n in subscript_start.pre_order() + ) + + def __str__(self) -> str: + """Render the line.""" + if not self: + return "\n" + + indent = " " * self.depth + leaves = iter(self.leaves) + first = next(leaves) + res = f"{first.prefix}{indent}{first.value}" + for leaf in leaves: + res += str(leaf) + for comment in itertools.chain.from_iterable(self.comments.values()): + res += str(comment) + return res + "\n" + + def __bool__(self) -> bool: + """Return True if the line has leaves or comments.""" + return bool(self.leaves or self.comments) + + +@dataclass +class EmptyLineTracker: + """Provides a stateful method that returns the number of potential extra + empty lines needed before and after the currently processed line. + + Note: this tracker works on lines that haven't been split yet. It assumes + the prefix of the first leaf consists of optional newlines. Those newlines + are consumed by `maybe_empty_lines()` and included in the computation. + """ + + is_pyi: bool = False + previous_line: Optional[Line] = None + previous_after: int = 0 + previous_defs: List[int] = Factory(list) + + def maybe_empty_lines(self, current_line: Line) -> Tuple[int, int]: + """Return the number of extra empty lines before and after the `current_line`. + + This is for separating `def`, `async def` and `class` with extra empty + lines (two on module-level). + """ + before, after = self._maybe_empty_lines(current_line) + before = ( + # Black should not insert empty lines at the beginning + # of the file + 0 + if self.previous_line is None + else before - self.previous_after + ) + self.previous_after = after + self.previous_line = current_line + return before, after + + def _maybe_empty_lines(self, current_line: Line) -> Tuple[int, int]: + max_allowed = 1 + if current_line.depth == 0: + max_allowed = 1 if self.is_pyi else 2 + if current_line.leaves: + # Consume the first leaf's extra newlines. + first_leaf = current_line.leaves[0] + before = first_leaf.prefix.count("\n") + before = min(before, max_allowed) + first_leaf.prefix = "" + else: + before = 0 + depth = current_line.depth + while self.previous_defs and self.previous_defs[-1] >= depth: + self.previous_defs.pop() + if self.is_pyi: + before = 0 if depth else 1 + else: + before = 1 if depth else 2 + if current_line.is_decorator or current_line.is_def or current_line.is_class: + return self._maybe_empty_lines_for_class_or_def(current_line, before) + + if ( + self.previous_line + and self.previous_line.is_import + and not current_line.is_import + and depth == self.previous_line.depth + ): + return (before or 1), 0 + + if ( + self.previous_line + and self.previous_line.is_class + and current_line.is_triple_quoted_string + ): + return before, 1 + + return before, 0 + + def _maybe_empty_lines_for_class_or_def( + self, current_line: Line, before: int + ) -> Tuple[int, int]: + if not current_line.is_decorator: + self.previous_defs.append(current_line.depth) + if self.previous_line is None: + # Don't insert empty lines before the first line in the file. + return 0, 0 + + if self.previous_line.is_decorator: + return 0, 0 + + if self.previous_line.depth < current_line.depth and ( + self.previous_line.is_class or self.previous_line.is_def + ): + return 0, 0 + + if ( + self.previous_line.is_comment + and self.previous_line.depth == current_line.depth + and before == 0 + ): + return 0, 0 + + if self.is_pyi: + if self.previous_line.depth > current_line.depth: + newlines = 1 + elif current_line.is_class or self.previous_line.is_class: + if current_line.is_stub_class and self.previous_line.is_stub_class: + # No blank line between classes with an empty body + newlines = 0 + else: + newlines = 1 + elif current_line.is_def and not self.previous_line.is_def: + # Blank line between a block of functions and a block of non-functions + newlines = 1 + else: + newlines = 0 + else: + newlines = 2 + if current_line.depth and newlines: + newlines -= 1 + return newlines, 0 + + +@dataclass +class LineGenerator(Visitor[Line]): + """Generates reformatted Line objects. Empty lines are not emitted. + + Note: destroys the tree it's visiting by mutating prefixes of its leaves + in ways that will no longer stringify to valid Python code on the tree. + """ + + is_pyi: bool = False + normalize_strings: bool = True + current_line: Line = Factory(Line) + remove_u_prefix: bool = False + + def line(self, indent: int = 0) -> Iterator[Line]: + """Generate a line. + + If the line is empty, only emit if it makes sense. + If the line is too long, split it first and then generate. + + If any lines were generated, set up a new current_line. + """ + if not self.current_line: + self.current_line.depth += indent + return # Line is empty, don't emit. Creating a new one unnecessary. + + complete_line = self.current_line + self.current_line = Line(depth=complete_line.depth + indent) + yield complete_line + + def visit_default(self, node: LN) -> Iterator[Line]: + """Default `visit_*()` implementation. Recurses to children of `node`.""" + if isinstance(node, Leaf): + any_open_brackets = self.current_line.bracket_tracker.any_open_brackets() + for comment in generate_comments(node): + if any_open_brackets: + # any comment within brackets is subject to splitting + self.current_line.append(comment) + elif comment.type == token.COMMENT: + # regular trailing comment + self.current_line.append(comment) + yield from self.line() + + else: + # regular standalone comment + yield from self.line() + + self.current_line.append(comment) + yield from self.line() + + normalize_prefix(node, inside_brackets=any_open_brackets) + if self.normalize_strings and node.type == token.STRING: + normalize_string_prefix(node, remove_u_prefix=self.remove_u_prefix) + normalize_string_quotes(node) + if node.type == token.NUMBER: + normalize_numeric_literal(node) + if node.type not in WHITESPACE: + self.current_line.append(node) + yield from super().visit_default(node) + + def visit_atom(self, node: Node) -> Iterator[Line]: + # Always make parentheses invisible around a single node, because it should + # not be needed (except in the case of yield, where removing the parentheses + # produces a SyntaxError). + if ( + len(node.children) == 3 + and isinstance(node.children[0], Leaf) + and node.children[0].type == token.LPAR + and isinstance(node.children[2], Leaf) + and node.children[2].type == token.RPAR + and isinstance(node.children[1], Leaf) + and not ( + node.children[1].type == token.NAME + and node.children[1].value == "yield" + ) + ): + node.children[0].value = "" + node.children[2].value = "" + yield from super().visit_default(node) + + def visit_factor(self, node: Node) -> Iterator[Line]: + """Force parentheses between a unary op and a binary power: + + -2 ** 8 -> -(2 ** 8) + """ + child = node.children[1] + if child.type == syms.power and len(child.children) == 3: + lpar = Leaf(token.LPAR, "(") + rpar = Leaf(token.RPAR, ")") + index = child.remove() or 0 + node.insert_child(index, Node(syms.atom, [lpar, child, rpar])) + yield from self.visit_default(node) + + def visit_INDENT(self, node: Node) -> Iterator[Line]: + """Increase indentation level, maybe yield a line.""" + # In blib2to3 INDENT never holds comments. + yield from self.line(+1) + yield from self.visit_default(node) + + def visit_DEDENT(self, node: Node) -> Iterator[Line]: + """Decrease indentation level, maybe yield a line.""" + # The current line might still wait for trailing comments. At DEDENT time + # there won't be any (they would be prefixes on the preceding NEWLINE). + # Emit the line then. + yield from self.line() + + # While DEDENT has no value, its prefix may contain standalone comments + # that belong to the current indentation level. Get 'em. + yield from self.visit_default(node) + + # Finally, emit the dedent. + yield from self.line(-1) + + def visit_stmt( + self, node: Node, keywords: Set[str], parens: Set[str] + ) -> Iterator[Line]: + """Visit a statement. + + This implementation is shared for `if`, `while`, `for`, `try`, `except`, + `def`, `with`, `class`, `assert` and assignments. + + The relevant Python language `keywords` for a given statement will be + NAME leaves within it. This methods puts those on a separate line. + + `parens` holds a set of string leaf values immediately after which + invisible parens should be put. + """ + normalize_invisible_parens(node, parens_after=parens) + for child in node.children: + if child.type == token.NAME and child.value in keywords: # type: ignore + yield from self.line() + + yield from self.visit(child) + + def visit_suite(self, node: Node) -> Iterator[Line]: + """Visit a suite.""" + if self.is_pyi and is_stub_suite(node): + yield from self.visit(node.children[2]) + else: + yield from self.visit_default(node) + + def visit_simple_stmt(self, node: Node) -> Iterator[Line]: + """Visit a statement without nested statements.""" + is_suite_like = node.parent and node.parent.type in STATEMENT + if is_suite_like: + if self.is_pyi and is_stub_body(node): + yield from self.visit_default(node) + else: + yield from self.line(+1) + yield from self.visit_default(node) + yield from self.line(-1) + + else: + if not self.is_pyi or not node.parent or not is_stub_suite(node.parent): + yield from self.line() + yield from self.visit_default(node) + + def visit_async_stmt(self, node: Node) -> Iterator[Line]: + """Visit `async def`, `async for`, `async with`.""" + yield from self.line() + + children = iter(node.children) + for child in children: + yield from self.visit(child) + + if child.type == token.ASYNC: + break + + internal_stmt = next(children) + for child in internal_stmt.children: + yield from self.visit(child) + + def visit_decorators(self, node: Node) -> Iterator[Line]: + """Visit decorators.""" + for child in node.children: + yield from self.line() + yield from self.visit(child) + + def visit_SEMI(self, leaf: Leaf) -> Iterator[Line]: + """Remove a semicolon and put the other statement on a separate line.""" + yield from self.line() + + def visit_ENDMARKER(self, leaf: Leaf) -> Iterator[Line]: + """End of file. Process outstanding comments and end with a newline.""" + yield from self.visit_default(leaf) + yield from self.line() + + def visit_STANDALONE_COMMENT(self, leaf: Leaf) -> Iterator[Line]: + if not self.current_line.bracket_tracker.any_open_brackets(): + yield from self.line() + yield from self.visit_default(leaf) + + def __attrs_post_init__(self) -> None: + """You are in a twisty little maze of passages.""" + v = self.visit_stmt + Ø: Set[str] = set() + self.visit_assert_stmt = partial(v, keywords={"assert"}, parens={"assert", ","}) + self.visit_if_stmt = partial( + v, keywords={"if", "else", "elif"}, parens={"if", "elif"} + ) + self.visit_while_stmt = partial(v, keywords={"while", "else"}, parens={"while"}) + self.visit_for_stmt = partial(v, keywords={"for", "else"}, parens={"for", "in"}) + self.visit_try_stmt = partial( + v, keywords={"try", "except", "else", "finally"}, parens=Ø + ) + self.visit_except_clause = partial(v, keywords={"except"}, parens=Ø) + self.visit_with_stmt = partial(v, keywords={"with"}, parens=Ø) + self.visit_funcdef = partial(v, keywords={"def"}, parens=Ø) + self.visit_classdef = partial(v, keywords={"class"}, parens=Ø) + self.visit_expr_stmt = partial(v, keywords=Ø, parens=ASSIGNMENTS) + self.visit_return_stmt = partial(v, keywords={"return"}, parens={"return"}) + self.visit_import_from = partial(v, keywords=Ø, parens={"import"}) + self.visit_del_stmt = partial(v, keywords=Ø, parens={"del"}) + self.visit_async_funcdef = self.visit_async_stmt + self.visit_decorated = self.visit_decorators + + +IMPLICIT_TUPLE = {syms.testlist, syms.testlist_star_expr, syms.exprlist} +BRACKET = {token.LPAR: token.RPAR, token.LSQB: token.RSQB, token.LBRACE: token.RBRACE} +OPENING_BRACKETS = set(BRACKET.keys()) +CLOSING_BRACKETS = set(BRACKET.values()) +BRACKETS = OPENING_BRACKETS | CLOSING_BRACKETS +ALWAYS_NO_SPACE = CLOSING_BRACKETS | {token.COMMA, STANDALONE_COMMENT} + + +def whitespace(leaf: Leaf, *, complex_subscript: bool) -> str: # noqa: C901 + """Return whitespace prefix if needed for the given `leaf`. + + `complex_subscript` signals whether the given leaf is part of a subscription + which has non-trivial arguments, like arithmetic expressions or function calls. + """ + NO = "" + SPACE = " " + DOUBLESPACE = " " + t = leaf.type + p = leaf.parent + v = leaf.value + if t in ALWAYS_NO_SPACE: + return NO + + if t == token.COMMENT: + return DOUBLESPACE + + assert p is not None, f"INTERNAL ERROR: hand-made leaf without parent: {leaf!r}" + if t == token.COLON and p.type not in { + syms.subscript, + syms.subscriptlist, + syms.sliceop, + }: + return NO + + prev = leaf.prev_sibling + if not prev: + prevp = preceding_leaf(p) + if not prevp or prevp.type in OPENING_BRACKETS: + return NO + + if t == token.COLON: + if prevp.type == token.COLON: + return NO + + elif prevp.type != token.COMMA and not complex_subscript: + return NO + + return SPACE + + if prevp.type == token.EQUAL: + if prevp.parent: + if prevp.parent.type in { + syms.arglist, + syms.argument, + syms.parameters, + syms.varargslist, + }: + return NO + + elif prevp.parent.type == syms.typedargslist: + # A bit hacky: if the equal sign has whitespace, it means we + # previously found it's a typed argument. So, we're using + # that, too. + return prevp.prefix + + elif prevp.type in VARARGS_SPECIALS: + if is_vararg(prevp, within=VARARGS_PARENTS | UNPACKING_PARENTS): + return NO + + elif prevp.type == token.COLON: + if prevp.parent and prevp.parent.type in {syms.subscript, syms.sliceop}: + return SPACE if complex_subscript else NO + + elif ( + prevp.parent + and prevp.parent.type == syms.factor + and prevp.type in MATH_OPERATORS + ): + return NO + + elif ( + prevp.type == token.RIGHTSHIFT + and prevp.parent + and prevp.parent.type == syms.shift_expr + and prevp.prev_sibling + and prevp.prev_sibling.type == token.NAME + and prevp.prev_sibling.value == "print" # type: ignore + ): + # Python 2 print chevron + return NO + + elif prev.type in OPENING_BRACKETS: + return NO + + if p.type in {syms.parameters, syms.arglist}: + # untyped function signatures or calls + if not prev or prev.type != token.COMMA: + return NO + + elif p.type == syms.varargslist: + # lambdas + if prev and prev.type != token.COMMA: + return NO + + elif p.type == syms.typedargslist: + # typed function signatures + if not prev: + return NO + + if t == token.EQUAL: + if prev.type != syms.tname: + return NO + + elif prev.type == token.EQUAL: + # A bit hacky: if the equal sign has whitespace, it means we + # previously found it's a typed argument. So, we're using that, too. + return prev.prefix + + elif prev.type != token.COMMA: + return NO + + elif p.type == syms.tname: + # type names + if not prev: + prevp = preceding_leaf(p) + if not prevp or prevp.type != token.COMMA: + return NO + + elif p.type == syms.trailer: + # attributes and calls + if t == token.LPAR or t == token.RPAR: + return NO + + if not prev: + if t == token.DOT: + prevp = preceding_leaf(p) + if not prevp or prevp.type != token.NUMBER: + return NO + + elif t == token.LSQB: + return NO + + elif prev.type != token.COMMA: + return NO + + elif p.type == syms.argument: + # single argument + if t == token.EQUAL: + return NO + + if not prev: + prevp = preceding_leaf(p) + if not prevp or prevp.type == token.LPAR: + return NO + + elif prev.type in {token.EQUAL} | VARARGS_SPECIALS: + return NO + + elif p.type == syms.decorator: + # decorators + return NO + + elif p.type == syms.dotted_name: + if prev: + return NO + + prevp = preceding_leaf(p) + if not prevp or prevp.type == token.AT or prevp.type == token.DOT: + return NO + + elif p.type == syms.classdef: + if t == token.LPAR: + return NO + + if prev and prev.type == token.LPAR: + return NO + + elif p.type in {syms.subscript, syms.sliceop}: + # indexing + if not prev: + assert p.parent is not None, "subscripts are always parented" + if p.parent.type == syms.subscriptlist: + return SPACE + + return NO + + elif not complex_subscript: + return NO + + elif p.type == syms.atom: + if prev and t == token.DOT: + # dots, but not the first one. + return NO + + elif p.type == syms.dictsetmaker: + # dict unpacking + if prev and prev.type == token.DOUBLESTAR: + return NO + + elif p.type in {syms.factor, syms.star_expr}: + # unary ops + if not prev: + prevp = preceding_leaf(p) + if not prevp or prevp.type in OPENING_BRACKETS: + return NO + + prevp_parent = prevp.parent + assert prevp_parent is not None + if prevp.type == token.COLON and prevp_parent.type in { + syms.subscript, + syms.sliceop, + }: + return NO + + elif prevp.type == token.EQUAL and prevp_parent.type == syms.argument: + return NO + + elif t in {token.NAME, token.NUMBER, token.STRING}: + return NO + + elif p.type == syms.import_from: + if t == token.DOT: + if prev and prev.type == token.DOT: + return NO + + elif t == token.NAME: + if v == "import": + return SPACE + + if prev and prev.type == token.DOT: + return NO + + elif p.type == syms.sliceop: + return NO + + return SPACE + + +def preceding_leaf(node: Optional[LN]) -> Optional[Leaf]: + """Return the first leaf that precedes `node`, if any.""" + while node: + res = node.prev_sibling + if res: + if isinstance(res, Leaf): + return res + + try: + return list(res.leaves())[-1] + + except IndexError: + return None + + node = node.parent + return None + + +def child_towards(ancestor: Node, descendant: LN) -> Optional[LN]: + """Return the child of `ancestor` that contains `descendant`.""" + node: Optional[LN] = descendant + while node and node.parent != ancestor: + node = node.parent + return node + + +def container_of(leaf: Leaf) -> LN: + """Return `leaf` or one of its ancestors that is the topmost container of it. + + By "container" we mean a node where `leaf` is the very first child. + """ + same_prefix = leaf.prefix + container: LN = leaf + while container: + parent = container.parent + if parent is None: + break + + if parent.children[0].prefix != same_prefix: + break + + if parent.type == syms.file_input: + break + + if parent.prev_sibling is not None and parent.prev_sibling.type in BRACKETS: + break + + container = parent + return container + + +def is_split_after_delimiter(leaf: Leaf, previous: Optional[Leaf] = None) -> Priority: + """Return the priority of the `leaf` delimiter, given a line break after it. + + The delimiter priorities returned here are from those delimiters that would + cause a line break after themselves. + + Higher numbers are higher priority. + """ + if leaf.type == token.COMMA: + return COMMA_PRIORITY + + return 0 + + +def is_split_before_delimiter(leaf: Leaf, previous: Optional[Leaf] = None) -> Priority: + """Return the priority of the `leaf` delimiter, given a line break before it. + + The delimiter priorities returned here are from those delimiters that would + cause a line break before themselves. + + Higher numbers are higher priority. + """ + if is_vararg(leaf, within=VARARGS_PARENTS | UNPACKING_PARENTS): + # * and ** might also be MATH_OPERATORS but in this case they are not. + # Don't treat them as a delimiter. + return 0 + + if ( + leaf.type == token.DOT + and leaf.parent + and leaf.parent.type not in {syms.import_from, syms.dotted_name} + and (previous is None or previous.type in CLOSING_BRACKETS) + ): + return DOT_PRIORITY + + if ( + leaf.type in MATH_OPERATORS + and leaf.parent + and leaf.parent.type not in {syms.factor, syms.star_expr} + ): + return MATH_PRIORITIES[leaf.type] + + if leaf.type in COMPARATORS: + return COMPARATOR_PRIORITY + + if ( + leaf.type == token.STRING + and previous is not None + and previous.type == token.STRING + ): + return STRING_PRIORITY + + if leaf.type not in {token.NAME, token.ASYNC}: + return 0 + + if ( + leaf.value == "for" + and leaf.parent + and leaf.parent.type in {syms.comp_for, syms.old_comp_for} + or leaf.type == token.ASYNC + ): + if ( + not isinstance(leaf.prev_sibling, Leaf) + or leaf.prev_sibling.value != "async" + ): + return COMPREHENSION_PRIORITY + + if ( + leaf.value == "if" + and leaf.parent + and leaf.parent.type in {syms.comp_if, syms.old_comp_if} + ): + return COMPREHENSION_PRIORITY + + if leaf.value in {"if", "else"} and leaf.parent and leaf.parent.type == syms.test: + return TERNARY_PRIORITY + + if leaf.value == "is": + return COMPARATOR_PRIORITY + + if ( + leaf.value == "in" + and leaf.parent + and leaf.parent.type in {syms.comp_op, syms.comparison} + and not ( + previous is not None + and previous.type == token.NAME + and previous.value == "not" + ) + ): + return COMPARATOR_PRIORITY + + if ( + leaf.value == "not" + and leaf.parent + and leaf.parent.type == syms.comp_op + and not ( + previous is not None + and previous.type == token.NAME + and previous.value == "is" + ) + ): + return COMPARATOR_PRIORITY + + if leaf.value in LOGIC_OPERATORS and leaf.parent: + return LOGIC_PRIORITY + + return 0 + + +FMT_OFF = {"# fmt: off", "# fmt:off", "# yapf: disable"} +FMT_ON = {"# fmt: on", "# fmt:on", "# yapf: enable"} + + +def generate_comments(leaf: LN) -> Iterator[Leaf]: + """Clean the prefix of the `leaf` and generate comments from it, if any. + + Comments in lib2to3 are shoved into the whitespace prefix. This happens + in `pgen2/driver.py:Driver.parse_tokens()`. This was a brilliant implementation + move because it does away with modifying the grammar to include all the + possible places in which comments can be placed. + + The sad consequence for us though is that comments don't "belong" anywhere. + This is why this function generates simple parentless Leaf objects for + comments. We simply don't know what the correct parent should be. + + No matter though, we can live without this. We really only need to + differentiate between inline and standalone comments. The latter don't + share the line with any code. + + Inline comments are emitted as regular token.COMMENT leaves. Standalone + are emitted with a fake STANDALONE_COMMENT token identifier. + """ + for pc in list_comments(leaf.prefix, is_endmarker=leaf.type == token.ENDMARKER): + yield Leaf(pc.type, pc.value, prefix="\n" * pc.newlines) + + +@dataclass +class ProtoComment: + """Describes a piece of syntax that is a comment. + + It's not a :class:`blib2to3.pytree.Leaf` so that: + + * it can be cached (`Leaf` objects should not be reused more than once as + they store their lineno, column, prefix, and parent information); + * `newlines` and `consumed` fields are kept separate from the `value`. This + simplifies handling of special marker comments like ``# fmt: off/on``. + """ + + type: int # token.COMMENT or STANDALONE_COMMENT + value: str # content of the comment + newlines: int # how many newlines before the comment + consumed: int # how many characters of the original leaf's prefix did we consume + + +@lru_cache(maxsize=4096) +def list_comments(prefix: str, *, is_endmarker: bool) -> List[ProtoComment]: + """Return a list of :class:`ProtoComment` objects parsed from the given `prefix`.""" + result: List[ProtoComment] = [] + if not prefix or "#" not in prefix: + return result + + consumed = 0 + nlines = 0 + ignored_lines = 0 + for index, line in enumerate(prefix.split("\n")): + consumed += len(line) + 1 # adding the length of the split '\n' + line = line.lstrip() + if not line: + nlines += 1 + if not line.startswith("#"): + # Escaped newlines outside of a comment are not really newlines at + # all. We treat a single-line comment following an escaped newline + # as a simple trailing comment. + if line.endswith("\\"): + ignored_lines += 1 + continue + + if index == ignored_lines and not is_endmarker: + comment_type = token.COMMENT # simple trailing comment + else: + comment_type = STANDALONE_COMMENT + comment = make_comment(line) + result.append( + ProtoComment( + type=comment_type, value=comment, newlines=nlines, consumed=consumed + ) + ) + nlines = 0 + return result + + +def make_comment(content: str) -> str: + """Return a consistently formatted comment from the given `content` string. + + All comments (except for "##", "#!", "#:", '#'", "#%%") should have a single + space between the hash sign and the content. + + If `content` didn't start with a hash sign, one is provided. + """ + content = content.rstrip() + if not content: + return "#" + + if content[0] == "#": + content = content[1:] + if content and content[0] not in " !:#'%": + content = " " + content + return "#" + content + + +def split_line( + line: Line, + line_length: int, + inner: bool = False, + features: Collection[Feature] = (), +) -> Iterator[Line]: + """Split a `line` into potentially many lines. + + They should fit in the allotted `line_length` but might not be able to. + `inner` signifies that there were a pair of brackets somewhere around the + current `line`, possibly transitively. This means we can fallback to splitting + by delimiters if the LHS/RHS don't yield any results. + + `features` are syntactical features that may be used in the output. + """ + if line.is_comment: + yield line + return + + line_str = str(line).strip("\n") + + if ( + not line.contains_uncollapsable_type_comments() + and not line.should_explode + and not line.is_collection_with_optional_trailing_comma + and ( + is_line_short_enough(line, line_length=line_length, line_str=line_str) + or line.contains_unsplittable_type_ignore() + ) + ): + yield line + return + + split_funcs: List[SplitFunc] + if line.is_def: + split_funcs = [left_hand_split] + else: + + def rhs(line: Line, features: Collection[Feature]) -> Iterator[Line]: + for omit in generate_trailers_to_omit(line, line_length): + lines = list(right_hand_split(line, line_length, features, omit=omit)) + if is_line_short_enough(lines[0], line_length=line_length): + yield from lines + return + + # All splits failed, best effort split with no omits. + # This mostly happens to multiline strings that are by definition + # reported as not fitting a single line. + yield from right_hand_split(line, line_length, features=features) + + if line.inside_brackets: + split_funcs = [delimiter_split, standalone_comment_split, rhs] + else: + split_funcs = [rhs] + for split_func in split_funcs: + # We are accumulating lines in `result` because we might want to abort + # mission and return the original line in the end, or attempt a different + # split altogether. + result: List[Line] = [] + try: + for l in split_func(line, features): + if str(l).strip("\n") == line_str: + raise CannotSplit("Split function returned an unchanged result") + + result.extend( + split_line( + l, line_length=line_length, inner=True, features=features + ) + ) + except CannotSplit: + continue + + else: + yield from result + break + + else: + yield line + + +def left_hand_split(line: Line, features: Collection[Feature] = ()) -> Iterator[Line]: + """Split line into many lines, starting with the first matching bracket pair. + + Note: this usually looks weird, only use this for function definitions. + Prefer RHS otherwise. This is why this function is not symmetrical with + :func:`right_hand_split` which also handles optional parentheses. + """ + tail_leaves: List[Leaf] = [] + body_leaves: List[Leaf] = [] + head_leaves: List[Leaf] = [] + current_leaves = head_leaves + matching_bracket = None + for leaf in line.leaves: + if ( + current_leaves is body_leaves + and leaf.type in CLOSING_BRACKETS + and leaf.opening_bracket is matching_bracket + ): + current_leaves = tail_leaves if body_leaves else head_leaves + current_leaves.append(leaf) + if current_leaves is head_leaves: + if leaf.type in OPENING_BRACKETS: + matching_bracket = leaf + current_leaves = body_leaves + if not matching_bracket: + raise CannotSplit("No brackets found") + + head = bracket_split_build_line(head_leaves, line, matching_bracket) + body = bracket_split_build_line(body_leaves, line, matching_bracket, is_body=True) + tail = bracket_split_build_line(tail_leaves, line, matching_bracket) + bracket_split_succeeded_or_raise(head, body, tail) + for result in (head, body, tail): + if result: + yield result + + +def right_hand_split( + line: Line, + line_length: int, + features: Collection[Feature] = (), + omit: Collection[LeafID] = (), +) -> Iterator[Line]: + """Split line into many lines, starting with the last matching bracket pair. + + If the split was by optional parentheses, attempt splitting without them, too. + `omit` is a collection of closing bracket IDs that shouldn't be considered for + this split. + + Note: running this function modifies `bracket_depth` on the leaves of `line`. + """ + tail_leaves: List[Leaf] = [] + body_leaves: List[Leaf] = [] + head_leaves: List[Leaf] = [] + current_leaves = tail_leaves + opening_bracket = None + closing_bracket = None + for leaf in reversed(line.leaves): + if current_leaves is body_leaves: + if leaf is opening_bracket: + current_leaves = head_leaves if body_leaves else tail_leaves + current_leaves.append(leaf) + if current_leaves is tail_leaves: + if leaf.type in CLOSING_BRACKETS and id(leaf) not in omit: + opening_bracket = leaf.opening_bracket + closing_bracket = leaf + current_leaves = body_leaves + if not (opening_bracket and closing_bracket and head_leaves): + # If there is no opening or closing_bracket that means the split failed and + # all content is in the tail. Otherwise, if `head_leaves` are empty, it means + # the matching `opening_bracket` wasn't available on `line` anymore. + raise CannotSplit("No brackets found") + + tail_leaves.reverse() + body_leaves.reverse() + head_leaves.reverse() + head = bracket_split_build_line(head_leaves, line, opening_bracket) + body = bracket_split_build_line(body_leaves, line, opening_bracket, is_body=True) + tail = bracket_split_build_line(tail_leaves, line, opening_bracket) + bracket_split_succeeded_or_raise(head, body, tail) + if ( + # the body shouldn't be exploded + not body.should_explode + # the opening bracket is an optional paren + and opening_bracket.type == token.LPAR + and not opening_bracket.value + # the closing bracket is an optional paren + and closing_bracket.type == token.RPAR + and not closing_bracket.value + # it's not an import (optional parens are the only thing we can split on + # in this case; attempting a split without them is a waste of time) + and not line.is_import + # there are no standalone comments in the body + and not body.contains_standalone_comments(0) + # and we can actually remove the parens + and can_omit_invisible_parens(body, line_length) + ): + omit = {id(closing_bracket), *omit} + try: + yield from right_hand_split(line, line_length, features=features, omit=omit) + return + + except CannotSplit: + if not ( + can_be_split(body) + or is_line_short_enough(body, line_length=line_length) + ): + raise CannotSplit( + "Splitting failed, body is still too long and can't be split." + ) + + elif head.contains_multiline_strings() or tail.contains_multiline_strings(): + raise CannotSplit( + "The current optional pair of parentheses is bound to fail to " + "satisfy the splitting algorithm because the head or the tail " + "contains multiline strings which by definition never fit one " + "line." + ) + + ensure_visible(opening_bracket) + ensure_visible(closing_bracket) + for result in (head, body, tail): + if result: + yield result + + +def bracket_split_succeeded_or_raise(head: Line, body: Line, tail: Line) -> None: + """Raise :exc:`CannotSplit` if the last left- or right-hand split failed. + + Do nothing otherwise. + + A left- or right-hand split is based on a pair of brackets. Content before + (and including) the opening bracket is left on one line, content inside the + brackets is put on a separate line, and finally content starting with and + following the closing bracket is put on a separate line. + + Those are called `head`, `body`, and `tail`, respectively. If the split + produced the same line (all content in `head`) or ended up with an empty `body` + and the `tail` is just the closing bracket, then it's considered failed. + """ + tail_len = len(str(tail).strip()) + if not body: + if tail_len == 0: + raise CannotSplit("Splitting brackets produced the same line") + + elif tail_len < 3: + raise CannotSplit( + f"Splitting brackets on an empty body to save " + f"{tail_len} characters is not worth it" + ) + + +def bracket_split_build_line( + leaves: List[Leaf], original: Line, opening_bracket: Leaf, *, is_body: bool = False +) -> Line: + """Return a new line with given `leaves` and respective comments from `original`. + + If `is_body` is True, the result line is one-indented inside brackets and as such + has its first leaf's prefix normalized and a trailing comma added when expected. + """ + result = Line(depth=original.depth) + if is_body: + result.inside_brackets = True + result.depth += 1 + if leaves: + # Since body is a new indent level, remove spurious leading whitespace. + normalize_prefix(leaves[0], inside_brackets=True) + # Ensure a trailing comma for imports and standalone function arguments, but + # be careful not to add one after any comments. + no_commas = original.is_def and not any( + l.type == token.COMMA for l in leaves + ) + + if original.is_import or no_commas: + for i in range(len(leaves) - 1, -1, -1): + if leaves[i].type == STANDALONE_COMMENT: + continue + elif leaves[i].type == token.COMMA: + break + else: + leaves.insert(i + 1, Leaf(token.COMMA, ",")) + break + # Populate the line + for leaf in leaves: + result.append(leaf, preformatted=True) + for comment_after in original.comments_after(leaf): + result.append(comment_after, preformatted=True) + if is_body: + result.should_explode = should_explode(result, opening_bracket) + return result + + +def dont_increase_indentation(split_func: SplitFunc) -> SplitFunc: + """Normalize prefix of the first leaf in every line returned by `split_func`. + + This is a decorator over relevant split functions. + """ + + @wraps(split_func) + def split_wrapper(line: Line, features: Collection[Feature] = ()) -> Iterator[Line]: + for l in split_func(line, features): + normalize_prefix(l.leaves[0], inside_brackets=True) + yield l + + return split_wrapper + + +@dont_increase_indentation +def delimiter_split(line: Line, features: Collection[Feature] = ()) -> Iterator[Line]: + """Split according to delimiters of the highest priority. + + If the appropriate Features are given, the split will add trailing commas + also in function signatures and calls that contain `*` and `**`. + """ + try: + last_leaf = line.leaves[-1] + except IndexError: + raise CannotSplit("Line empty") + + bt = line.bracket_tracker + try: + delimiter_priority = bt.max_delimiter_priority(exclude={id(last_leaf)}) + except ValueError: + raise CannotSplit("No delimiters found") + + if delimiter_priority == DOT_PRIORITY: + if bt.delimiter_count_with_priority(delimiter_priority) == 1: + raise CannotSplit("Splitting a single attribute from its owner looks wrong") + + current_line = Line(depth=line.depth, inside_brackets=line.inside_brackets) + lowest_depth = sys.maxsize + trailing_comma_safe = True + + def append_to_line(leaf: Leaf) -> Iterator[Line]: + """Append `leaf` to current line or to new line if appending impossible.""" + nonlocal current_line + try: + current_line.append_safe(leaf, preformatted=True) + except ValueError: + yield current_line + + current_line = Line(depth=line.depth, inside_brackets=line.inside_brackets) + current_line.append(leaf) + + for leaf in line.leaves: + yield from append_to_line(leaf) + + for comment_after in line.comments_after(leaf): + yield from append_to_line(comment_after) + + lowest_depth = min(lowest_depth, leaf.bracket_depth) + if leaf.bracket_depth == lowest_depth: + if is_vararg(leaf, within={syms.typedargslist}): + trailing_comma_safe = ( + trailing_comma_safe and Feature.TRAILING_COMMA_IN_DEF in features + ) + elif is_vararg(leaf, within={syms.arglist, syms.argument}): + trailing_comma_safe = ( + trailing_comma_safe and Feature.TRAILING_COMMA_IN_CALL in features + ) + + leaf_priority = bt.delimiters.get(id(leaf)) + if leaf_priority == delimiter_priority: + yield current_line + + current_line = Line(depth=line.depth, inside_brackets=line.inside_brackets) + if current_line: + if ( + trailing_comma_safe + and delimiter_priority == COMMA_PRIORITY + and current_line.leaves[-1].type != token.COMMA + and current_line.leaves[-1].type != STANDALONE_COMMENT + ): + current_line.append(Leaf(token.COMMA, ",")) + yield current_line + + +@dont_increase_indentation +def standalone_comment_split( + line: Line, features: Collection[Feature] = () +) -> Iterator[Line]: + """Split standalone comments from the rest of the line.""" + if not line.contains_standalone_comments(0): + raise CannotSplit("Line does not have any standalone comments") + + current_line = Line(depth=line.depth, inside_brackets=line.inside_brackets) + + def append_to_line(leaf: Leaf) -> Iterator[Line]: + """Append `leaf` to current line or to new line if appending impossible.""" + nonlocal current_line + try: + current_line.append_safe(leaf, preformatted=True) + except ValueError: + yield current_line + + current_line = Line(depth=line.depth, inside_brackets=line.inside_brackets) + current_line.append(leaf) + + for leaf in line.leaves: + yield from append_to_line(leaf) + + for comment_after in line.comments_after(leaf): + yield from append_to_line(comment_after) + + if current_line: + yield current_line + + +def is_import(leaf: Leaf) -> bool: + """Return True if the given leaf starts an import statement.""" + p = leaf.parent + t = leaf.type + v = leaf.value + return bool( + t == token.NAME + and ( + (v == "import" and p and p.type == syms.import_name) + or (v == "from" and p and p.type == syms.import_from) + ) + ) + + +def is_type_comment(leaf: Leaf, suffix: str = "") -> bool: + """Return True if the given leaf is a special comment. + Only returns true for type comments for now.""" + t = leaf.type + v = leaf.value + return t in {token.COMMENT, t == STANDALONE_COMMENT} and v.startswith( + "# type:" + suffix + ) + + +def normalize_prefix(leaf: Leaf, *, inside_brackets: bool) -> None: + """Leave existing extra newlines if not `inside_brackets`. Remove everything + else. + + Note: don't use backslashes for formatting or you'll lose your voting rights. + """ + if not inside_brackets: + spl = leaf.prefix.split("#") + if "\\" not in spl[0]: + nl_count = spl[-1].count("\n") + if len(spl) > 1: + nl_count -= 1 + leaf.prefix = "\n" * nl_count + return + + leaf.prefix = "" + + +def normalize_string_prefix(leaf: Leaf, remove_u_prefix: bool = False) -> None: + """Make all string prefixes lowercase. + + If remove_u_prefix is given, also removes any u prefix from the string. + + Note: Mutates its argument. + """ + match = re.match(r"^([furbFURB]*)(.*)$", leaf.value, re.DOTALL) + assert match is not None, f"failed to match string {leaf.value!r}" + orig_prefix = match.group(1) + new_prefix = orig_prefix.lower() + if remove_u_prefix: + new_prefix = new_prefix.replace("u", "") + leaf.value = f"{new_prefix}{match.group(2)}" + + +def normalize_string_quotes(leaf: Leaf) -> None: + """Prefer double quotes but only if it doesn't cause more escaping. + + Adds or removes backslashes as appropriate. Doesn't parse and fix + strings nested in f-strings (yet). + + Note: Mutates its argument. + """ + value = leaf.value.lstrip("furbFURB") + if value[:3] == '"""': + return + + elif value[:3] == "'''": + orig_quote = "'''" + new_quote = '"""' + elif value[0] == '"': + orig_quote = '"' + new_quote = "'" + else: + orig_quote = "'" + new_quote = '"' + first_quote_pos = leaf.value.find(orig_quote) + if first_quote_pos == -1: + return # There's an internal error + + prefix = leaf.value[:first_quote_pos] + unescaped_new_quote = re.compile(rf"(([^\\]|^)(\\\\)*){new_quote}") + escaped_new_quote = re.compile(rf"([^\\]|^)\\((?:\\\\)*){new_quote}") + escaped_orig_quote = re.compile(rf"([^\\]|^)\\((?:\\\\)*){orig_quote}") + body = leaf.value[first_quote_pos + len(orig_quote) : -len(orig_quote)] + if "r" in prefix.casefold(): + if unescaped_new_quote.search(body): + # There's at least one unescaped new_quote in this raw string + # so converting is impossible + return + + # Do not introduce or remove backslashes in raw strings + new_body = body + else: + # remove unnecessary escapes + new_body = sub_twice(escaped_new_quote, rf"\1\2{new_quote}", body) + if body != new_body: + # Consider the string without unnecessary escapes as the original + body = new_body + leaf.value = f"{prefix}{orig_quote}{body}{orig_quote}" + new_body = sub_twice(escaped_orig_quote, rf"\1\2{orig_quote}", new_body) + new_body = sub_twice(unescaped_new_quote, rf"\1\\{new_quote}", new_body) + if "f" in prefix.casefold(): + matches = re.findall( + r""" + (?:[^{]|^)\{ # start of the string or a non-{ followed by a single { + ([^{].*?) # contents of the brackets except if begins with {{ + \}(?:[^}]|$) # A } followed by end of the string or a non-} + """, + new_body, + re.VERBOSE, + ) + for m in matches: + if "\\" in str(m): + # Do not introduce backslashes in interpolated expressions + return + if new_quote == '"""' and new_body[-1:] == '"': + # edge case: + new_body = new_body[:-1] + '\\"' + orig_escape_count = body.count("\\") + new_escape_count = new_body.count("\\") + if new_escape_count > orig_escape_count: + return # Do not introduce more escaping + + if new_escape_count == orig_escape_count and orig_quote == '"': + return # Prefer double quotes + + leaf.value = f"{prefix}{new_quote}{new_body}{new_quote}" + + +def normalize_numeric_literal(leaf: Leaf) -> None: + """Normalizes numeric (float, int, and complex) literals. + + All letters used in the representation are normalized to lowercase (except + in Python 2 long literals). + """ + text = leaf.value.lower() + if text.startswith(("0o", "0b")): + # Leave octal and binary literals alone. + pass + elif text.startswith("0x"): + # Change hex literals to upper case. + before, after = text[:2], text[2:] + text = f"{before}{after.upper()}" + elif "e" in text: + before, after = text.split("e") + sign = "" + if after.startswith("-"): + after = after[1:] + sign = "-" + elif after.startswith("+"): + after = after[1:] + before = format_float_or_int_string(before) + text = f"{before}e{sign}{after}" + elif text.endswith(("j", "l")): + number = text[:-1] + suffix = text[-1] + # Capitalize in "2L" because "l" looks too similar to "1". + if suffix == "l": + suffix = "L" + text = f"{format_float_or_int_string(number)}{suffix}" + else: + text = format_float_or_int_string(text) + leaf.value = text + + +def format_float_or_int_string(text: str) -> str: + """Formats a float string like "1.0".""" + if "." not in text: + return text + + before, after = text.split(".") + return f"{before or 0}.{after or 0}" + + +def normalize_invisible_parens(node: Node, parens_after: Set[str]) -> None: + """Make existing optional parentheses invisible or create new ones. + + `parens_after` is a set of string leaf values immediately after which parens + should be put. + + Standardizes on visible parentheses for single-element tuples, and keeps + existing visible parentheses for other tuples and generator expressions. + """ + for pc in list_comments(node.prefix, is_endmarker=False): + if pc.value in FMT_OFF: + # This `node` has a prefix with `# fmt: off`, don't mess with parens. + return + + check_lpar = False + for index, child in enumerate(list(node.children)): + # Add parentheses around long tuple unpacking in assignments. + if ( + index == 0 + and isinstance(child, Node) + and child.type == syms.testlist_star_expr + ): + check_lpar = True + + if check_lpar: + if is_walrus_assignment(child): + continue + if child.type == syms.atom: + # Determines if the underlying atom should be surrounded with + # invisible params - also makes parens invisible recursively + # within the atom and removes repeated invisible parens within + # the atom + should_surround_with_parens = maybe_make_parens_invisible_in_atom( + child, parent=node + ) + + if should_surround_with_parens: + lpar = Leaf(token.LPAR, "") + rpar = Leaf(token.RPAR, "") + index = child.remove() or 0 + node.insert_child(index, Node(syms.atom, [lpar, child, rpar])) + elif is_one_tuple(child): + # wrap child in visible parentheses + lpar = Leaf(token.LPAR, "(") + rpar = Leaf(token.RPAR, ")") + child.remove() + node.insert_child(index, Node(syms.atom, [lpar, child, rpar])) + elif node.type == syms.import_from: + # "import from" nodes store parentheses directly as part of + # the statement + if child.type == token.LPAR: + # make parentheses invisible + child.value = "" # type: ignore + node.children[-1].value = "" # type: ignore + elif child.type != token.STAR: + # insert invisible parentheses + node.insert_child(index, Leaf(token.LPAR, "")) + node.append_child(Leaf(token.RPAR, "")) + break + + elif not (isinstance(child, Leaf) and is_multiline_string(child)): + # wrap child in invisible parentheses + lpar = Leaf(token.LPAR, "") + rpar = Leaf(token.RPAR, "") + index = child.remove() or 0 + prefix = child.prefix + child.prefix = "" + new_child = Node(syms.atom, [lpar, child, rpar]) + new_child.prefix = prefix + node.insert_child(index, new_child) + + check_lpar = isinstance(child, Leaf) and child.value in parens_after + + +def normalize_fmt_off(node: Node) -> None: + """Convert content between `# fmt: off`/`# fmt: on` into standalone comments.""" + try_again = True + while try_again: + try_again = convert_one_fmt_off_pair(node) + + +def convert_one_fmt_off_pair(node: Node) -> bool: + """Convert content of a single `# fmt: off`/`# fmt: on` into a standalone comment. + + Returns True if a pair was converted. + """ + for leaf in node.leaves(): + previous_consumed = 0 + for comment in list_comments(leaf.prefix, is_endmarker=False): + if comment.value in FMT_OFF: + # We only want standalone comments. If there's no previous leaf or + # the previous leaf is indentation, it's a standalone comment in + # disguise. + if comment.type != STANDALONE_COMMENT: + prev = preceding_leaf(leaf) + if prev and prev.type not in WHITESPACE: + continue + + ignored_nodes = list(generate_ignored_nodes(leaf)) + if not ignored_nodes: + continue + + first = ignored_nodes[0] # Can be a container node with the `leaf`. + parent = first.parent + prefix = first.prefix + first.prefix = prefix[comment.consumed :] + hidden_value = ( + comment.value + "\n" + "".join(str(n) for n in ignored_nodes) + ) + if hidden_value.endswith("\n"): + # That happens when one of the `ignored_nodes` ended with a NEWLINE + # leaf (possibly followed by a DEDENT). + hidden_value = hidden_value[:-1] + first_idx = None + for ignored in ignored_nodes: + index = ignored.remove() + if first_idx is None: + first_idx = index + assert parent is not None, "INTERNAL ERROR: fmt: on/off handling (1)" + assert first_idx is not None, "INTERNAL ERROR: fmt: on/off handling (2)" + parent.insert_child( + first_idx, + Leaf( + STANDALONE_COMMENT, + hidden_value, + prefix=prefix[:previous_consumed] + "\n" * comment.newlines, + ), + ) + return True + + previous_consumed = comment.consumed + + return False + + +def generate_ignored_nodes(leaf: Leaf) -> Iterator[LN]: + """Starting from the container of `leaf`, generate all leaves until `# fmt: on`. + + Stops at the end of the block. + """ + container: Optional[LN] = container_of(leaf) + while container is not None and container.type != token.ENDMARKER: + for comment in list_comments(container.prefix, is_endmarker=False): + if comment.value in FMT_ON: + return + + yield container + + container = container.next_sibling + + +def maybe_make_parens_invisible_in_atom(node: LN, parent: LN) -> bool: + """If it's safe, make the parens in the atom `node` invisible, recursively. + Additionally, remove repeated, adjacent invisible parens from the atom `node` + as they are redundant. + + Returns whether the node should itself be wrapped in invisible parentheses. + + """ + if ( + node.type != syms.atom + or is_empty_tuple(node) + or is_one_tuple(node) + or (is_yield(node) and parent.type != syms.expr_stmt) + or max_delimiter_priority_in_atom(node) >= COMMA_PRIORITY + ): + return False + + first = node.children[0] + last = node.children[-1] + if first.type == token.LPAR and last.type == token.RPAR: + middle = node.children[1] + # make parentheses invisible + first.value = "" # type: ignore + last.value = "" # type: ignore + maybe_make_parens_invisible_in_atom(middle, parent=parent) + + if is_atom_with_invisible_parens(middle): + # Strip the invisible parens from `middle` by replacing + # it with the child in-between the invisible parens + middle.replace(middle.children[1]) + + return False + + return True + + +def is_atom_with_invisible_parens(node: LN) -> bool: + """Given a `LN`, determines whether it's an atom `node` with invisible + parens. Useful in dedupe-ing and normalizing parens. + """ + if isinstance(node, Leaf) or node.type != syms.atom: + return False + + first, last = node.children[0], node.children[-1] + return ( + isinstance(first, Leaf) + and first.type == token.LPAR + and first.value == "" + and isinstance(last, Leaf) + and last.type == token.RPAR + and last.value == "" + ) + + +def is_empty_tuple(node: LN) -> bool: + """Return True if `node` holds an empty tuple.""" + return ( + node.type == syms.atom + and len(node.children) == 2 + and node.children[0].type == token.LPAR + and node.children[1].type == token.RPAR + ) + + +def unwrap_singleton_parenthesis(node: LN) -> Optional[LN]: + """Returns `wrapped` if `node` is of the shape ( wrapped ). + + Parenthesis can be optional. Returns None otherwise""" + if len(node.children) != 3: + return None + lpar, wrapped, rpar = node.children + if not (lpar.type == token.LPAR and rpar.type == token.RPAR): + return None + + return wrapped + + +def is_one_tuple(node: LN) -> bool: + """Return True if `node` holds a tuple with one element, with or without parens.""" + if node.type == syms.atom: + gexp = unwrap_singleton_parenthesis(node) + if gexp is None or gexp.type != syms.testlist_gexp: + return False + + return len(gexp.children) == 2 and gexp.children[1].type == token.COMMA + + return ( + node.type in IMPLICIT_TUPLE + and len(node.children) == 2 + and node.children[1].type == token.COMMA + ) + + +def is_walrus_assignment(node: LN) -> bool: + """Return True iff `node` is of the shape ( test := test )""" + inner = unwrap_singleton_parenthesis(node) + return inner is not None and inner.type == syms.namedexpr_test + + +def is_yield(node: LN) -> bool: + """Return True if `node` holds a `yield` or `yield from` expression.""" + if node.type == syms.yield_expr: + return True + + if node.type == token.NAME and node.value == "yield": # type: ignore + return True + + if node.type != syms.atom: + return False + + if len(node.children) != 3: + return False + + lpar, expr, rpar = node.children + if lpar.type == token.LPAR and rpar.type == token.RPAR: + return is_yield(expr) + + return False + + +def is_vararg(leaf: Leaf, within: Set[NodeType]) -> bool: + """Return True if `leaf` is a star or double star in a vararg or kwarg. + + If `within` includes VARARGS_PARENTS, this applies to function signatures. + If `within` includes UNPACKING_PARENTS, it applies to right hand-side + extended iterable unpacking (PEP 3132) and additional unpacking + generalizations (PEP 448). + """ + if leaf.type not in VARARGS_SPECIALS or not leaf.parent: + return False + + p = leaf.parent + if p.type == syms.star_expr: + # Star expressions are also used as assignment targets in extended + # iterable unpacking (PEP 3132). See what its parent is instead. + if not p.parent: + return False + + p = p.parent + + return p.type in within + + +def is_multiline_string(leaf: Leaf) -> bool: + """Return True if `leaf` is a multiline string that actually spans many lines.""" + value = leaf.value.lstrip("furbFURB") + return value[:3] in {'"""', "'''"} and "\n" in value + + +def is_stub_suite(node: Node) -> bool: + """Return True if `node` is a suite with a stub body.""" + if ( + len(node.children) != 4 + or node.children[0].type != token.NEWLINE + or node.children[1].type != token.INDENT + or node.children[3].type != token.DEDENT + ): + return False + + return is_stub_body(node.children[2]) + + +def is_stub_body(node: LN) -> bool: + """Return True if `node` is a simple statement containing an ellipsis.""" + if not isinstance(node, Node) or node.type != syms.simple_stmt: + return False + + if len(node.children) != 2: + return False + + child = node.children[0] + return ( + child.type == syms.atom + and len(child.children) == 3 + and all(leaf == Leaf(token.DOT, ".") for leaf in child.children) + ) + + +def max_delimiter_priority_in_atom(node: LN) -> Priority: + """Return maximum delimiter priority inside `node`. + + This is specific to atoms with contents contained in a pair of parentheses. + If `node` isn't an atom or there are no enclosing parentheses, returns 0. + """ + if node.type != syms.atom: + return 0 + + first = node.children[0] + last = node.children[-1] + if not (first.type == token.LPAR and last.type == token.RPAR): + return 0 + + bt = BracketTracker() + for c in node.children[1:-1]: + if isinstance(c, Leaf): + bt.mark(c) + else: + for leaf in c.leaves(): + bt.mark(leaf) + try: + return bt.max_delimiter_priority() + + except ValueError: + return 0 + + +def ensure_visible(leaf: Leaf) -> None: + """Make sure parentheses are visible. + + They could be invisible as part of some statements (see + :func:`normalize_invisible_parens` and :func:`visit_import_from`). + """ + if leaf.type == token.LPAR: + leaf.value = "(" + elif leaf.type == token.RPAR: + leaf.value = ")" + + +def should_explode(line: Line, opening_bracket: Leaf) -> bool: + """Should `line` immediately be split with `delimiter_split()` after RHS?""" + + if not ( + opening_bracket.parent + and opening_bracket.parent.type in {syms.atom, syms.import_from} + and opening_bracket.value in "[{(" + ): + return False + + try: + last_leaf = line.leaves[-1] + exclude = {id(last_leaf)} if last_leaf.type == token.COMMA else set() + max_priority = line.bracket_tracker.max_delimiter_priority(exclude=exclude) + except (IndexError, ValueError): + return False + + return max_priority == COMMA_PRIORITY + + +def get_features_used(node: Node) -> Set[Feature]: + """Return a set of (relatively) new Python features used in this file. + + Currently looking for: + - f-strings; + - underscores in numeric literals; + - trailing commas after * or ** in function signatures and calls; + - positional only arguments in function signatures and lambdas; + """ + features: Set[Feature] = set() + for n in node.pre_order(): + if n.type == token.STRING: + value_head = n.value[:2] # type: ignore + if value_head in {'f"', 'F"', "f'", "F'", "rf", "fr", "RF", "FR"}: + features.add(Feature.F_STRINGS) + + elif n.type == token.NUMBER: + if "_" in n.value: # type: ignore + features.add(Feature.NUMERIC_UNDERSCORES) + + elif n.type == token.SLASH: + if n.parent and n.parent.type in {syms.typedargslist, syms.arglist}: + features.add(Feature.POS_ONLY_ARGUMENTS) + + elif n.type == token.COLONEQUAL: + features.add(Feature.ASSIGNMENT_EXPRESSIONS) + + elif ( + n.type in {syms.typedargslist, syms.arglist} + and n.children + and n.children[-1].type == token.COMMA + ): + if n.type == syms.typedargslist: + feature = Feature.TRAILING_COMMA_IN_DEF + else: + feature = Feature.TRAILING_COMMA_IN_CALL + + for ch in n.children: + if ch.type in STARS: + features.add(feature) + + if ch.type == syms.argument: + for argch in ch.children: + if argch.type in STARS: + features.add(feature) + + return features + + +def detect_target_versions(node: Node) -> Set[TargetVersion]: + """Detect the version to target based on the nodes used.""" + features = get_features_used(node) + return { + version for version in TargetVersion if features <= VERSION_TO_FEATURES[version] + } + + +def generate_trailers_to_omit(line: Line, line_length: int) -> Iterator[Set[LeafID]]: + """Generate sets of closing bracket IDs that should be omitted in a RHS. + + Brackets can be omitted if the entire trailer up to and including + a preceding closing bracket fits in one line. + + Yielded sets are cumulative (contain results of previous yields, too). First + set is empty. + """ + + omit: Set[LeafID] = set() + yield omit + + length = 4 * line.depth + opening_bracket = None + closing_bracket = None + inner_brackets: Set[LeafID] = set() + for index, leaf, leaf_length in enumerate_with_length(line, reversed=True): + length += leaf_length + if length > line_length: + break + + has_inline_comment = leaf_length > len(leaf.value) + len(leaf.prefix) + if leaf.type == STANDALONE_COMMENT or has_inline_comment: + break + + if opening_bracket: + if leaf is opening_bracket: + opening_bracket = None + elif leaf.type in CLOSING_BRACKETS: + inner_brackets.add(id(leaf)) + elif leaf.type in CLOSING_BRACKETS: + if index > 0 and line.leaves[index - 1].type in OPENING_BRACKETS: + # Empty brackets would fail a split so treat them as "inner" + # brackets (e.g. only add them to the `omit` set if another + # pair of brackets was good enough. + inner_brackets.add(id(leaf)) + continue + + if closing_bracket: + omit.add(id(closing_bracket)) + omit.update(inner_brackets) + inner_brackets.clear() + yield omit + + if leaf.value: + opening_bracket = leaf.opening_bracket + closing_bracket = leaf + + +def get_future_imports(node: Node) -> Set[str]: + """Return a set of __future__ imports in the file.""" + imports: Set[str] = set() + + def get_imports_from_children(children: List[LN]) -> Generator[str, None, None]: + for child in children: + if isinstance(child, Leaf): + if child.type == token.NAME: + yield child.value + elif child.type == syms.import_as_name: + orig_name = child.children[0] + assert isinstance(orig_name, Leaf), "Invalid syntax parsing imports" + assert orig_name.type == token.NAME, "Invalid syntax parsing imports" + yield orig_name.value + elif child.type == syms.import_as_names: + yield from get_imports_from_children(child.children) + else: + raise AssertionError("Invalid syntax parsing imports") + + for child in node.children: + if child.type != syms.simple_stmt: + break + first_child = child.children[0] + if isinstance(first_child, Leaf): + # Continue looking if we see a docstring; otherwise stop. + if ( + len(child.children) == 2 + and first_child.type == token.STRING + and child.children[1].type == token.NEWLINE + ): + continue + else: + break + elif first_child.type == syms.import_from: + module_name = first_child.children[1] + if not isinstance(module_name, Leaf) or module_name.value != "__future__": + break + imports |= set(get_imports_from_children(first_child.children[3:])) + else: + break + return imports + + +def gen_python_files_in_dir( + path: Path, + root: Path, + include: Pattern[str], + exclude: Pattern[str], + report: "Report", +) -> Iterator[Path]: + """Generate all files under `path` whose paths are not excluded by the + `exclude` regex, but are included by the `include` regex. + + Symbolic links pointing outside of the `root` directory are ignored. + + `report` is where output about exclusions goes. + """ + assert root.is_absolute(), f"INTERNAL ERROR: `root` must be absolute but is {root}" + for child in path.iterdir(): + try: + normalized_path = "/" + child.resolve().relative_to(root).as_posix() + except ValueError: + if child.is_symlink(): + report.path_ignored( + child, f"is a symbolic link that points outside {root}" + ) + continue + + raise + + if child.is_dir(): + normalized_path += "/" + exclude_match = exclude.search(normalized_path) + if exclude_match and exclude_match.group(0): + report.path_ignored(child, f"matches the --exclude regular expression") + continue + + if child.is_dir(): + yield from gen_python_files_in_dir(child, root, include, exclude, report) + + elif child.is_file(): + include_match = include.search(normalized_path) + if include_match: + yield child + + +@lru_cache() +def find_project_root(srcs: Iterable[str]) -> Path: + """Return a directory containing .git, .hg, or pyproject.toml. + + That directory can be one of the directories passed in `srcs` or their + common parent. + + If no directory in the tree contains a marker that would specify it's the + project root, the root of the file system is returned. + """ + if not srcs: + return Path("/").resolve() + + common_base = min(Path(src).resolve() for src in srcs) + if common_base.is_dir(): + # Append a fake file so `parents` below returns `common_base_dir`, too. + common_base /= "fake-file" + for directory in common_base.parents: + if (directory / ".git").is_dir(): + return directory + + if (directory / ".hg").is_dir(): + return directory + + if (directory / "pyproject.toml").is_file(): + return directory + + return directory + + +@dataclass +class Report: + """Provides a reformatting counter. Can be rendered with `str(report)`.""" + + check: bool = False + quiet: bool = False + verbose: bool = False + change_count: int = 0 + same_count: int = 0 + failure_count: int = 0 + + def done(self, src: Path, changed: Changed) -> None: + """Increment the counter for successful reformatting. Write out a message.""" + if changed is Changed.YES: + reformatted = "would reformat" if self.check else "reformatted" + if self.verbose or not self.quiet: + out(f"{reformatted} {src}") + self.change_count += 1 + else: + if self.verbose: + if changed is Changed.NO: + msg = f"{src} already well formatted, good job." + else: + msg = f"{src} wasn't modified on disk since last run." + out(msg, bold=False) + self.same_count += 1 + + def failed(self, src: Path, message: str) -> None: + """Increment the counter for failed reformatting. Write out a message.""" + err(f"error: cannot format {src}: {message}") + self.failure_count += 1 + + def path_ignored(self, path: Path, message: str) -> None: + if self.verbose: + out(f"{path} ignored: {message}", bold=False) + + @property + def return_code(self) -> int: + """Return the exit code that the app should use. + + This considers the current state of changed files and failures: + - if there were any failures, return 123; + - if any files were changed and --check is being used, return 1; + - otherwise return 0. + """ + # According to http://tldp.org/LDP/abs/html/exitcodes.html starting with + # 126 we have special return codes reserved by the shell. + if self.failure_count: + return 123 + + elif self.change_count and self.check: + return 1 + + return 0 + + def __str__(self) -> str: + """Render a color report of the current state. + + Use `click.unstyle` to remove colors. + """ + if self.check: + reformatted = "would be reformatted" + unchanged = "would be left unchanged" + failed = "would fail to reformat" + else: + reformatted = "reformatted" + unchanged = "left unchanged" + failed = "failed to reformat" + report = [] + if self.change_count: + s = "s" if self.change_count > 1 else "" + report.append( + click.style(f"{self.change_count} file{s} {reformatted}", bold=True) + ) + if self.same_count: + s = "s" if self.same_count > 1 else "" + report.append(f"{self.same_count} file{s} {unchanged}") + if self.failure_count: + s = "s" if self.failure_count > 1 else "" + report.append( + click.style(f"{self.failure_count} file{s} {failed}", fg="red") + ) + return ", ".join(report) + "." + + +def parse_ast(src: str) -> Union[ast.AST, ast3.AST, ast27.AST]: + filename = "" + if sys.version_info >= (3, 8): + # TODO: support Python 4+ ;) + for minor_version in range(sys.version_info[1], 4, -1): + try: + return ast.parse(src, filename, feature_version=(3, minor_version)) + except SyntaxError: + continue + else: + for feature_version in (7, 6): + try: + return ast3.parse(src, filename, feature_version=feature_version) + except SyntaxError: + continue + + return ast27.parse(src) + + +def _fixup_ast_constants( + node: Union[ast.AST, ast3.AST, ast27.AST] +) -> Union[ast.AST, ast3.AST, ast27.AST]: + """Map ast nodes deprecated in 3.8 to Constant.""" + # casts are required until this is released: + # https://github.com/python/typeshed/pull/3142 + if isinstance(node, (ast.Str, ast3.Str, ast27.Str, ast.Bytes, ast3.Bytes)): + return cast(ast.AST, ast.Constant(value=node.s)) + elif isinstance(node, (ast.Num, ast3.Num, ast27.Num)): + return cast(ast.AST, ast.Constant(value=node.n)) + elif isinstance(node, (ast.NameConstant, ast3.NameConstant)): + return cast(ast.AST, ast.Constant(value=node.value)) + return node + + +def assert_equivalent(src: str, dst: str) -> None: + """Raise AssertionError if `src` and `dst` aren't equivalent.""" + + def _v(node: Union[ast.AST, ast3.AST, ast27.AST], depth: int = 0) -> Iterator[str]: + """Simple visitor generating strings to compare ASTs by content.""" + + node = _fixup_ast_constants(node) + + yield f"{' ' * depth}{node.__class__.__name__}(" + + for field in sorted(node._fields): + # TypeIgnore has only one field 'lineno' which breaks this comparison + type_ignore_classes = (ast3.TypeIgnore, ast27.TypeIgnore) + if sys.version_info >= (3, 8): + type_ignore_classes += (ast.TypeIgnore,) + if isinstance(node, type_ignore_classes): + break + + try: + value = getattr(node, field) + except AttributeError: + continue + + yield f"{' ' * (depth+1)}{field}=" + + if isinstance(value, list): + for item in value: + # Ignore nested tuples within del statements, because we may insert + # parentheses and they change the AST. + if ( + field == "targets" + and isinstance(node, (ast.Delete, ast3.Delete, ast27.Delete)) + and isinstance(item, (ast.Tuple, ast3.Tuple, ast27.Tuple)) + ): + for item in item.elts: + yield from _v(item, depth + 2) + elif isinstance(item, (ast.AST, ast3.AST, ast27.AST)): + yield from _v(item, depth + 2) + + elif isinstance(value, (ast.AST, ast3.AST, ast27.AST)): + yield from _v(value, depth + 2) + + else: + yield f"{' ' * (depth+2)}{value!r}, # {value.__class__.__name__}" + + yield f"{' ' * depth}) # /{node.__class__.__name__}" + + try: + src_ast = parse_ast(src) + except Exception as exc: + raise AssertionError( + f"cannot use --safe with this file; failed to parse source file. " + f"AST error message: {exc}" + ) + + try: + dst_ast = parse_ast(dst) + except Exception as exc: + log = dump_to_file("".join(traceback.format_tb(exc.__traceback__)), dst) + raise AssertionError( + f"INTERNAL ERROR: Black produced invalid code: {exc}. " + f"Please report a bug on https://github.com/psf/black/issues. " + f"This invalid output might be helpful: {log}" + ) from None + + src_ast_str = "\n".join(_v(src_ast)) + dst_ast_str = "\n".join(_v(dst_ast)) + if src_ast_str != dst_ast_str: + log = dump_to_file(diff(src_ast_str, dst_ast_str, "src", "dst")) + raise AssertionError( + f"INTERNAL ERROR: Black produced code that is not equivalent to " + f"the source. " + f"Please report a bug on https://github.com/psf/black/issues. " + f"This diff might be helpful: {log}" + ) from None + + +def assert_stable(src: str, dst: str, mode: FileMode) -> None: + """Raise AssertionError if `dst` reformats differently the second time.""" + newdst = format_str(dst, mode=mode) + if dst != newdst: + log = dump_to_file( + diff(src, dst, "source", "first pass"), + diff(dst, newdst, "first pass", "second pass"), + ) + raise AssertionError( + f"INTERNAL ERROR: Black produced different code on the second pass " + f"of the formatter. " + f"Please report a bug on https://github.com/psf/black/issues. " + f"This diff might be helpful: {log}" + ) from None + + +def dump_to_file(*output: str) -> str: + """Dump `output` to a temporary file. Return path to the file.""" + with tempfile.NamedTemporaryFile( + mode="w", prefix="blk_", suffix=".log", delete=False, encoding="utf8" + ) as f: + for lines in output: + f.write(lines) + if lines and lines[-1] != "\n": + f.write("\n") + return f.name + + +@contextmanager +def nullcontext() -> Iterator[None]: + """Return context manager that does nothing. + Similar to `nullcontext` from python 3.7""" + yield + + +def diff(a: str, b: str, a_name: str, b_name: str) -> str: + """Return a unified diff string between strings `a` and `b`.""" + import difflib + + a_lines = [line + "\n" for line in a.split("\n")] + b_lines = [line + "\n" for line in b.split("\n")] + return "".join( + difflib.unified_diff(a_lines, b_lines, fromfile=a_name, tofile=b_name, n=5) + ) + + +def cancel(tasks: Iterable[asyncio.Task]) -> None: + """asyncio signal handler that cancels all `tasks` and reports to stderr.""" + err("Aborted!") + for task in tasks: + task.cancel() + + +def shutdown(loop: asyncio.AbstractEventLoop) -> None: + """Cancel all pending tasks on `loop`, wait for them, and close the loop.""" + try: + if sys.version_info[:2] >= (3, 7): + all_tasks = asyncio.all_tasks + else: + all_tasks = asyncio.Task.all_tasks + # This part is borrowed from asyncio/runners.py in Python 3.7b2. + to_cancel = [task for task in all_tasks(loop) if not task.done()] + if not to_cancel: + return + + for task in to_cancel: + task.cancel() + loop.run_until_complete( + asyncio.gather(*to_cancel, loop=loop, return_exceptions=True) + ) + finally: + # `concurrent.futures.Future` objects cannot be cancelled once they + # are already running. There might be some when the `shutdown()` happened. + # Silence their logger's spew about the event loop being closed. + cf_logger = logging.getLogger("concurrent.futures") + cf_logger.setLevel(logging.CRITICAL) + loop.close() + + +def sub_twice(regex: Pattern[str], replacement: str, original: str) -> str: + """Replace `regex` with `replacement` twice on `original`. + + This is used by string normalization to perform replaces on + overlapping matches. + """ + return regex.sub(replacement, regex.sub(replacement, original)) + + +def re_compile_maybe_verbose(regex: str) -> Pattern[str]: + """Compile a regular expression string in `regex`. + + If it contains newlines, use verbose mode. + """ + if "\n" in regex: + regex = "(?x)" + regex + return re.compile(regex) + + +def enumerate_reversed(sequence: Sequence[T]) -> Iterator[Tuple[Index, T]]: + """Like `reversed(enumerate(sequence))` if that were possible.""" + index = len(sequence) - 1 + for element in reversed(sequence): + yield (index, element) + index -= 1 + + +def enumerate_with_length( + line: Line, reversed: bool = False +) -> Iterator[Tuple[Index, Leaf, int]]: + """Return an enumeration of leaves with their length. + + Stops prematurely on multiline strings and standalone comments. + """ + op = cast( + Callable[[Sequence[Leaf]], Iterator[Tuple[Index, Leaf]]], + enumerate_reversed if reversed else enumerate, + ) + for index, leaf in op(line.leaves): + length = len(leaf.prefix) + len(leaf.value) + if "\n" in leaf.value: + return # Multiline strings, we can't continue. + + for comment in line.comments_after(leaf): + length += len(comment.value) + + yield index, leaf, length + + +def is_line_short_enough(line: Line, *, line_length: int, line_str: str = "") -> bool: + """Return True if `line` is no longer than `line_length`. + + Uses the provided `line_str` rendering, if any, otherwise computes a new one. + """ + if not line_str: + line_str = str(line).strip("\n") + return ( + len(line_str) <= line_length + and "\n" not in line_str # multiline strings + and not line.contains_standalone_comments() + ) + + +def can_be_split(line: Line) -> bool: + """Return False if the line cannot be split *for sure*. + + This is not an exhaustive search but a cheap heuristic that we can use to + avoid some unfortunate formattings (mostly around wrapping unsplittable code + in unnecessary parentheses). + """ + leaves = line.leaves + if len(leaves) < 2: + return False + + if leaves[0].type == token.STRING and leaves[1].type == token.DOT: + call_count = 0 + dot_count = 0 + next = leaves[-1] + for leaf in leaves[-2::-1]: + if leaf.type in OPENING_BRACKETS: + if next.type not in CLOSING_BRACKETS: + return False + + call_count += 1 + elif leaf.type == token.DOT: + dot_count += 1 + elif leaf.type == token.NAME: + if not (next.type == token.DOT or next.type in OPENING_BRACKETS): + return False + + elif leaf.type not in CLOSING_BRACKETS: + return False + + if dot_count > 1 and call_count > 1: + return False + + return True + + +def can_omit_invisible_parens(line: Line, line_length: int) -> bool: + """Does `line` have a shape safe to reformat without optional parens around it? + + Returns True for only a subset of potentially nice looking formattings but + the point is to not return false positives that end up producing lines that + are too long. + """ + bt = line.bracket_tracker + if not bt.delimiters: + # Without delimiters the optional parentheses are useless. + return True + + max_priority = bt.max_delimiter_priority() + if bt.delimiter_count_with_priority(max_priority) > 1: + # With more than one delimiter of a kind the optional parentheses read better. + return False + + if max_priority == DOT_PRIORITY: + # A single stranded method call doesn't require optional parentheses. + return True + + assert len(line.leaves) >= 2, "Stranded delimiter" + + first = line.leaves[0] + second = line.leaves[1] + penultimate = line.leaves[-2] + last = line.leaves[-1] + + # With a single delimiter, omit if the expression starts or ends with + # a bracket. + if first.type in OPENING_BRACKETS and second.type not in CLOSING_BRACKETS: + remainder = False + length = 4 * line.depth + for _index, leaf, leaf_length in enumerate_with_length(line): + if leaf.type in CLOSING_BRACKETS and leaf.opening_bracket is first: + remainder = True + if remainder: + length += leaf_length + if length > line_length: + break + + if leaf.type in OPENING_BRACKETS: + # There are brackets we can further split on. + remainder = False + + else: + # checked the entire string and line length wasn't exceeded + if len(line.leaves) == _index + 1: + return True + + # Note: we are not returning False here because a line might have *both* + # a leading opening bracket and a trailing closing bracket. If the + # opening bracket doesn't match our rule, maybe the closing will. + + if ( + last.type == token.RPAR + or last.type == token.RBRACE + or ( + # don't use indexing for omitting optional parentheses; + # it looks weird + last.type == token.RSQB + and last.parent + and last.parent.type != syms.trailer + ) + ): + if penultimate.type in OPENING_BRACKETS: + # Empty brackets don't help. + return False + + if is_multiline_string(first): + # Additional wrapping of a multiline string in this situation is + # unnecessary. + return True + + length = 4 * line.depth + seen_other_brackets = False + for _index, leaf, leaf_length in enumerate_with_length(line): + length += leaf_length + if leaf is last.opening_bracket: + if seen_other_brackets or length <= line_length: + return True + + elif leaf.type in OPENING_BRACKETS: + # There are brackets we can further split on. + seen_other_brackets = True + + return False + + +def get_cache_file(mode: FileMode) -> Path: + return CACHE_DIR / f"cache.{mode.get_cache_key()}.pickle" + + +def read_cache(mode: FileMode) -> Cache: + """Read the cache if it exists and is well formed. + + If it is not well formed, the call to write_cache later should resolve the issue. + """ + cache_file = get_cache_file(mode) + if not cache_file.exists(): + return {} + + with cache_file.open("rb") as fobj: + try: + cache: Cache = pickle.load(fobj) + except pickle.UnpicklingError: + return {} + + return cache + + +def get_cache_info(path: Path) -> CacheInfo: + """Return the information used to check if a file is already formatted or not.""" + stat = path.stat() + return stat.st_mtime, stat.st_size + + +def filter_cached(cache: Cache, sources: Iterable[Path]) -> Tuple[Set[Path], Set[Path]]: + """Split an iterable of paths in `sources` into two sets. + + The first contains paths of files that modified on disk or are not in the + cache. The other contains paths to non-modified files. + """ + todo, done = set(), set() + for src in sources: + src = src.resolve() + if cache.get(src) != get_cache_info(src): + todo.add(src) + else: + done.add(src) + return todo, done + + +def write_cache(cache: Cache, sources: Iterable[Path], mode: FileMode) -> None: + """Update the cache file.""" + cache_file = get_cache_file(mode) + try: + CACHE_DIR.mkdir(parents=True, exist_ok=True) + new_cache = {**cache, **{src.resolve(): get_cache_info(src) for src in sources}} + with tempfile.NamedTemporaryFile(dir=str(cache_file.parent), delete=False) as f: + pickle.dump(new_cache, f, protocol=pickle.HIGHEST_PROTOCOL) + os.replace(f.name, cache_file) + except OSError: + pass + + +def patch_click() -> None: + """Make Click not crash. + + On certain misconfigured environments, Python 3 selects the ASCII encoding as the + default which restricts paths that it can access during the lifetime of the + application. Click refuses to work in this scenario by raising a RuntimeError. + + In case of Black the likelihood that non-ASCII characters are going to be used in + file paths is minimal since it's Python source code. Moreover, this crash was + spurious on Python 3.7 thanks to PEP 538 and PEP 540. + """ + try: + from click import core + from click import _unicodefun # type: ignore + except ModuleNotFoundError: + return + + for module in (core, _unicodefun): + if hasattr(module, "_verify_python3_env"): + module._verify_python3_env = lambda: None + + +def patched_main() -> None: + freeze_support() + patch_click() + main() + + +if __name__ == "__main__": + patched_main()