X-Git-Url: https://git.madduck.net/etc/vim.git/blobdiff_plain/21ab37a5d92c866a289320cba7c4689df70b3342..703faa323391165d13ee41d3ed4c417e62cd0ca2:/black.py diff --git a/black.py b/black.py index 2850ae1..3ab4bc7 100644 --- a/black.py +++ b/black.py @@ -1,6 +1,9 @@ +import ast import asyncio -from asyncio.base_events import BaseEventLoop -from concurrent.futures import Executor, ProcessPoolExecutor +from abc import ABC, abstractmethod +from collections import defaultdict +from concurrent.futures import Executor, ThreadPoolExecutor, ProcessPoolExecutor +from contextlib import contextmanager from datetime import datetime from enum import Enum from functools import lru_cache, partial, wraps @@ -11,11 +14,12 @@ from multiprocessing import Manager, freeze_support import os from pathlib import Path import pickle -import re +import regex as re import signal import sys import tempfile import tokenize +import traceback from typing import ( Any, Callable, @@ -30,16 +34,23 @@ from typing import ( Pattern, Sequence, Set, + Sized, Tuple, + Type, TypeVar, Union, cast, + TYPE_CHECKING, ) +from typing_extensions import Final +from mypy_extensions import mypyc_attr from appdirs import user_cache_dir -from attr import dataclass, evolve, Factory +from dataclasses import dataclass, field, replace import click import toml +from typed_ast import ast3, ast27 +from pathspec import PathSpec # lib2to3 fork from blib2to3.pytree import Node, Leaf, type_repr @@ -48,15 +59,18 @@ from blib2to3.pgen2 import driver, token from blib2to3.pgen2.grammar import Grammar from blib2to3.pgen2.parse import ParseError +from _black_version import version as __version__ + +if TYPE_CHECKING: + import colorama # noqa: F401 -__version__ = "18.9b0" DEFAULT_LINE_LENGTH = 88 -DEFAULT_EXCLUDES = ( - r"/(\.eggs|\.git|\.hg|\.mypy_cache|\.nox|\.tox|\.venv|_build|buck-out|build|dist)/" -) +DEFAULT_EXCLUDES = r"/(\.eggs|\.git|\.hg|\.mypy_cache|\.nox|\.tox|\.venv|\.svn|_build|buck-out|build|dist)/" # noqa: B950 DEFAULT_INCLUDES = r"\.pyi?$" CACHE_DIR = Path(user_cache_dir("black", version=__version__)) +STRING_PREFIX_CHARS: Final = "furbFURB" # All possible string prefix characters. + # types FileContent = str @@ -64,11 +78,13 @@ Encoding = str NewLine = str Depth = int NodeType = int +ParserState = int LeafID = int +StringID = int Priority = int Index = int LN = Union[Leaf, Node] -SplitFunc = Callable[["Line", bool], Iterator["Line"]] +Transformer = Callable[["Line", Collection["Feature"]], Iterator["Line"]] Timestamp = float FileSize = int CacheInfo = Tuple[Timestamp, FileSize] @@ -84,7 +100,11 @@ class NothingChanged(UserWarning): """Raised when reformatted code is the same as source.""" -class CannotSplit(Exception): +class CannotTransform(Exception): + """Base class for errors raised by Transformers.""" + + +class CannotSplit(CannotTransform): """A readable split that fits the allotted line length is impossible.""" @@ -92,17 +112,51 @@ class InvalidInput(ValueError): """Raised when input source code fails all parse attempts.""" +T = TypeVar("T") +E = TypeVar("E", bound=Exception) + + +class Ok(Generic[T]): + def __init__(self, value: T) -> None: + self._value = value + + def ok(self) -> T: + return self._value + + +class Err(Generic[E]): + def __init__(self, e: E) -> None: + self._e = e + + def err(self) -> E: + return self._e + + +# The 'Result' return type is used to implement an error-handling model heavily +# influenced by that used by the Rust programming language +# (see https://doc.rust-lang.org/book/ch09-00-error-handling.html). +Result = Union[Ok[T], Err[E]] +TResult = Result[T, CannotTransform] # (T)ransform Result +TMatchResult = TResult[Index] + + class WriteBack(Enum): NO = 0 YES = 1 DIFF = 2 CHECK = 3 + COLOR_DIFF = 4 @classmethod - def from_configuration(cls, *, check: bool, diff: bool) -> "WriteBack": + def from_configuration( + cls, *, check: bool, diff: bool, color: bool = False + ) -> "WriteBack": if check and not diff: return cls.CHECK + if diff and color: + return cls.COLOR_DIFF + return cls.DIFF if diff else cls.YES @@ -113,20 +167,19 @@ class Changed(Enum): class TargetVersion(Enum): - PYPY35 = 1 - CPY27 = 2 - CPY33 = 3 - CPY34 = 4 - CPY35 = 5 - CPY36 = 6 - CPY37 = 7 - CPY38 = 8 + PY27 = 2 + PY33 = 3 + PY34 = 4 + PY35 = 5 + PY36 = 6 + PY37 = 7 + PY38 = 8 def is_python2(self) -> bool: - return self is TargetVersion.CPY27 + return self is TargetVersion.PY27 -PY36_VERSIONS = {TargetVersion.CPY36, TargetVersion.CPY37, TargetVersion.CPY38} +PY36_VERSIONS = {TargetVersion.PY36, TargetVersion.PY37, TargetVersion.PY38} class Feature(Enum): @@ -134,39 +187,57 @@ class Feature(Enum): UNICODE_LITERALS = 1 F_STRINGS = 2 NUMERIC_UNDERSCORES = 3 - TRAILING_COMMA = 4 + 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.CPY27: set(), - TargetVersion.PYPY35: {Feature.UNICODE_LITERALS, Feature.F_STRINGS}, - TargetVersion.CPY33: {Feature.UNICODE_LITERALS}, - TargetVersion.CPY34: {Feature.UNICODE_LITERALS}, - TargetVersion.CPY35: {Feature.UNICODE_LITERALS, Feature.TRAILING_COMMA}, - TargetVersion.CPY36: { + 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, + Feature.TRAILING_COMMA_IN_CALL, + Feature.TRAILING_COMMA_IN_DEF, + Feature.ASYNC_IDENTIFIERS, }, - TargetVersion.CPY37: { + TargetVersion.PY37: { Feature.UNICODE_LITERALS, Feature.F_STRINGS, Feature.NUMERIC_UNDERSCORES, - Feature.TRAILING_COMMA, + Feature.TRAILING_COMMA_IN_CALL, + Feature.TRAILING_COMMA_IN_DEF, + Feature.ASYNC_KEYWORDS, }, - TargetVersion.CPY38: { + TargetVersion.PY38: { Feature.UNICODE_LITERALS, Feature.F_STRINGS, Feature.NUMERIC_UNDERSCORES, - Feature.TRAILING_COMMA, + Feature.TRAILING_COMMA_IN_CALL, + Feature.TRAILING_COMMA_IN_DEF, + Feature.ASYNC_KEYWORDS, + Feature.ASSIGNMENT_EXPRESSIONS, + Feature.POS_ONLY_ARGUMENTS, }, } @dataclass -class FileMode: - target_versions: Set[TargetVersion] = Factory(set) +class Mode: + target_versions: Set[TargetVersion] = field(default_factory=set) line_length: int = DEFAULT_LINE_LENGTH string_normalization: bool = True is_pyi: bool = False @@ -188,30 +259,46 @@ class FileMode: return ".".join(parts) +# Legacy name, left for integrations. +FileMode = Mode + + def supports_feature(target_versions: Set[TargetVersion], feature: Feature) -> bool: return all(feature in VERSION_TO_FEATURES[version] for version in target_versions) +def find_pyproject_toml(path_search_start: str) -> Optional[str]: + """Find the absolute filepath to a pyproject.toml if it exists""" + path_project_root = find_project_root(path_search_start) + path_pyproject_toml = path_project_root / "pyproject.toml" + return str(path_pyproject_toml) if path_pyproject_toml.is_file() else None + + +def parse_pyproject_toml(path_config: str) -> Dict[str, Any]: + """Parse a pyproject toml file, pulling out relevant parts for Black + + If parsing fails, will raise a toml.TomlDecodeError + """ + pyproject_toml = toml.load(path_config) + config = pyproject_toml.get("tool", {}).get("black", {}) + return {k.replace("--", "").replace("-", "_"): v for k, v in config.items()} + + def read_pyproject_toml( - ctx: click.Context, param: click.Parameter, value: Union[str, int, bool, None] + ctx: click.Context, param: click.Parameter, value: Optional[str] ) -> Optional[str]: """Inject Black configuration from "pyproject.toml" into defaults in `ctx`. Returns the path to a successfully found and read configuration file, None otherwise. """ - assert not isinstance(value, (int, bool)), "Invalid parameter type passed" if not value: - root = find_project_root(ctx.params.get("src", ())) - path = root / "pyproject.toml" - if path.is_file(): - value = str(path) - else: + value = find_pyproject_toml(ctx.params.get("src", ())) + if value is None: return None try: - pyproject_toml = toml.load(value) - config = pyproject_toml.get("tool", {}).get("black", {}) + config = parse_pyproject_toml(value) except (toml.TomlDecodeError, OSError) as e: raise click.FileError( filename=value, hint=f"Error reading configuration file: {e}" @@ -220,15 +307,34 @@ def read_pyproject_toml( if not config: return None - if ctx.default_map is None: - ctx.default_map = {} - ctx.default_map.update( # type: ignore # bad types in .pyi - {k.replace("--", "").replace("-", "_"): v for k, v in config.items()} - ) + target_version = config.get("target_version") + if target_version is not None and not isinstance(target_version, list): + raise click.BadOptionUsage( + "target-version", f"Config key target-version must be a list" + ) + + default_map: Dict[str, Any] = {} + if ctx.default_map: + default_map.update(ctx.default_map) + default_map.update(config) + + ctx.default_map = default_map return value +def target_version_option_callback( + c: click.Context, p: Union[click.Option, click.Parameter], v: Tuple[str, ...] +) -> List[TargetVersion]: + """Compute the target versions from a --target-version flag. + + This is its own function because mypy couldn't infer the type correctly + when it was a lambda, causing mypyc trouble. + """ + return [TargetVersion[val.upper()] for val in v] + + @click.command(context_settings=dict(help_option_names=["-h", "--help"])) +@click.option("-c", "--code", type=str, help="Format the code passed in as a string.") @click.option( "-l", "--line-length", @@ -241,19 +347,19 @@ def read_pyproject_toml( "-t", "--target-version", type=click.Choice([v.name.lower() for v in TargetVersion]), - callback=lambda c, p, v: [TargetVersion[val.upper()] for val in v], + callback=target_version_option_callback, multiple=True, help=( - "Python versions that should be supported by Black's output. [default: " - "per-file auto-detection]" + "Python versions that should be supported by Black's output. [default: per-file" + " auto-detection]" ), ) @click.option( "--pyi", is_flag=True, help=( - "Format all input files like typing stubs regardless of file extension " - "(useful when piping source on standard input)." + "Format all input files like typing stubs regardless of file extension (useful" + " when piping source on standard input)." ), ) @click.option( @@ -266,9 +372,9 @@ def read_pyproject_toml( "--check", is_flag=True, help=( - "Don't write the files back, just return the status. Return code 0 " - "means nothing would change. Return code 1 means some files would be " - "reformatted. Return code 123 means there was an internal error." + "Don't write the files back, just return the status. Return code 0 means" + " nothing would change. Return code 1 means some files would be reformatted." + " Return code 123 means there was an internal error." ), ) @click.option( @@ -276,6 +382,11 @@ def read_pyproject_toml( is_flag=True, help="Don't write the files back, just output a diff for each file on stdout.", ) +@click.option( + "--color/--no-color", + is_flag=True, + help="Show colored diff. Only applies when `--diff` is given.", +) @click.option( "--fast/--safe", is_flag=True, @@ -286,11 +397,10 @@ def read_pyproject_toml( type=str, default=DEFAULT_INCLUDES, help=( - "A regular expression that matches files and directories that should be " - "included on recursive searches. An empty value means all files are " - "included regardless of the name. Use forward slashes for directories on " - "all platforms (Windows, too). Exclusions are calculated first, inclusions " - "later." + "A regular expression that matches files and directories that should be" + " included on recursive searches. An empty value means all files are included" + " regardless of the name. Use forward slashes for directories on all platforms" + " (Windows, too). Exclusions are calculated first, inclusions later." ), show_default=True, ) @@ -299,20 +409,28 @@ def read_pyproject_toml( type=str, default=DEFAULT_EXCLUDES, help=( - "A regular expression that matches files and directories that should be " - "excluded on recursive searches. An empty value means no paths are excluded. " - "Use forward slashes for directories on all platforms (Windows, too). " - "Exclusions are calculated first, inclusions later." + "A regular expression that matches files and directories that should be" + " excluded on recursive searches. An empty value means no paths are excluded." + " Use forward slashes for directories on all platforms (Windows, too). " + " Exclusions are calculated first, inclusions later." ), show_default=True, ) +@click.option( + "--force-exclude", + type=str, + help=( + "Like --exclude, but files and directories matching this regex will be " + "excluded even when they are passed explicitly as arguments" + ), +) @click.option( "-q", "--quiet", is_flag=True, help=( - "Don't emit non-error messages to stderr. Errors are still emitted, " - "silence those with 2>/dev/null." + "Don't emit non-error messages to stderr. Errors are still emitted; silence" + " those with 2>/dev/null." ), ) @click.option( @@ -320,8 +438,8 @@ def read_pyproject_toml( "--verbose", is_flag=True, help=( - "Also emit messages to stderr about files that were not changed or were " - "ignored due to --exclude=." + "Also emit messages to stderr about files that were not changed or were ignored" + " due to --exclude=." ), ) @click.version_option(version=__version__) @@ -336,7 +454,12 @@ def read_pyproject_toml( @click.option( "--config", type=click.Path( - exists=False, file_okay=True, dir_okay=False, readable=True, allow_dash=False + exists=True, + file_okay=True, + dir_okay=False, + readable=True, + allow_dash=False, + path_type=str, ), is_eager=True, callback=read_pyproject_toml, @@ -345,10 +468,12 @@ def read_pyproject_toml( @click.pass_context def main( ctx: click.Context, + code: Optional[str], line_length: int, target_version: List[TargetVersion], check: bool, diff: bool, + color: bool, fast: bool, pyi: bool, skip_string_normalization: bool, @@ -356,17 +481,18 @@ def main( verbose: bool, include: str, exclude: str, - src: Tuple[str], + force_exclude: Optional[str], + src: Tuple[str, ...], config: Optional[str], ) -> None: """The uncompromising code formatter.""" - write_back = WriteBack.from_configuration(check=check, diff=diff) + write_back = WriteBack.from_configuration(check=check, diff=diff, color=color) if target_version: versions = set(target_version) else: # We'll autodetect later. versions = set() - mode = FileMode( + mode = Mode( target_versions=versions, line_length=line_length, is_pyi=pyi, @@ -374,6 +500,60 @@ def main( ) 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) + report = Report(check=check, diff=diff, quiet=quiet, verbose=verbose) + sources = get_sources( + ctx=ctx, + src=src, + quiet=quiet, + verbose=verbose, + include=include, + exclude=exclude, + force_exclude=force_exclude, + report=report, + ) + + path_empty( + sources, + "No Python files are present to be formatted. Nothing to do 😴", + quiet, + verbose, + ctx, + ) + + if len(sources) == 1: + reformat_one( + src=sources.pop(), + fast=fast, + write_back=write_back, + mode=mode, + report=report, + ) + else: + reformat_many( + sources=sources, fast=fast, write_back=write_back, mode=mode, report=report + ) + + if verbose or not quiet: + out("Oh no! 💥 💔 💥" if report.return_code else "All done! ✨ 🍰 ✨") + click.secho(str(report), err=True) + ctx.exit(report.return_code) + + +def get_sources( + *, + ctx: click.Context, + src: Tuple[str, ...], + quiet: bool, + verbose: bool, + include: str, + exclude: str, + force_exclude: Optional[str], + report: "Report", +) -> Set[Path]: + """Compute the set of files to be formatted.""" try: include_regex = re_compile_maybe_verbose(include) except re.error: @@ -384,64 +564,65 @@ def main( except re.error: err(f"Invalid regular expression for exclude given: {exclude!r}") ctx.exit(2) - report = Report(check=check, quiet=quiet, verbose=verbose) + try: + force_exclude_regex = ( + re_compile_maybe_verbose(force_exclude) if force_exclude else None + ) + except re.error: + err(f"Invalid regular expression for force_exclude given: {force_exclude!r}") + ctx.exit(2) + root = find_project_root(src) sources: Set[Path] = set() + path_empty(src, "No Path provided. Nothing to do 😴", quiet, verbose, ctx) + exclude_regexes = [exclude_regex] + if force_exclude_regex is not None: + exclude_regexes.append(force_exclude_regex) + for s in src: p = Path(s) if p.is_dir(): sources.update( - gen_python_files_in_dir(p, root, include_regex, exclude_regex, report) + gen_python_files( + p.iterdir(), + root, + include_regex, + exclude_regexes, + report, + get_gitignore(root), + ) ) - elif p.is_file() or s == "-": - # if a file was explicitly given, we don't care about its extension + elif s == "-": sources.add(p) + elif p.is_file(): + sources.update( + gen_python_files( + [p], root, None, exclude_regexes, report, get_gitignore(root) + ) + ) else: err(f"invalid path: {s}") - if len(sources) == 0: - if verbose or not quiet: - out("No paths given. Nothing to do 😴") - ctx.exit(0) + return sources - if len(sources) == 1: - reformat_one( - src=sources.pop(), - fast=fast, - write_back=write_back, - mode=mode, - report=report, - ) - else: - loop = asyncio.get_event_loop() - executor = ProcessPoolExecutor(max_workers=os.cpu_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) - if verbose or not quiet: - bang = "💥 💔 💥" if report.return_code else "✨ 🍰 ✨" - out(f"All done! {bang}") - click.secho(str(report), err=True) - ctx.exit(report.return_code) + +def path_empty( + src: Sized, msg: str, quiet: bool, verbose: bool, ctx: click.Context +) -> None: + """ + Exit if there is no `src` provided for formatting + """ + if len(src) == 0: + if verbose or not quiet: + out(msg) + ctx.exit(0) def reformat_one( - src: Path, fast: bool, write_back: WriteBack, mode: FileMode, report: "Report" + src: Path, fast: bool, write_back: WriteBack, mode: Mode, report: "Report" ) -> None: """Reformat a single file under `src` without spawning child processes. - If `quiet` is True, non-error messages are not output. `line_length`, - `write_back`, `fast` and `pyi` options are passed to + `fast`, `write_back`, and `mode` options are passed to :func:`format_file_in_place` or :func:`format_stdin_to_stdout`. """ try: @@ -469,20 +650,57 @@ def reformat_one( report.failed(src, str(exc)) +def reformat_many( + sources: Set[Path], fast: bool, write_back: WriteBack, mode: Mode, report: "Report" +) -> None: + """Reformat multiple files using a ProcessPoolExecutor.""" + executor: Executor + loop = asyncio.get_event_loop() + worker_count = os.cpu_count() + if sys.platform == "win32": + # Work around https://bugs.python.org/issue26903 + worker_count = min(worker_count, 61) + try: + executor = ProcessPoolExecutor(max_workers=worker_count) + except OSError: + # we arrive here if the underlying system does not support multi-processing + # like in AWS Lambda, in which case we gracefully fallback to + # a ThreadPollExecutor with just a single worker (more workers would not do us + # any good due to the Global Interpreter Lock) + executor = ThreadPoolExecutor(max_workers=1) + + try: + loop.run_until_complete( + schedule_formatting( + sources=sources, + fast=fast, + write_back=write_back, + mode=mode, + report=report, + loop=loop, + executor=executor, + ) + ) + finally: + shutdown(loop) + if executor is not None: + executor.shutdown() + + async def schedule_formatting( sources: Set[Path], fast: bool, write_back: WriteBack, - mode: FileMode, + mode: Mode, report: "Report", - loop: BaseEventLoop, + loop: asyncio.AbstractEventLoop, executor: Executor, ) -> None: """Run formatting of `sources` in parallel using the provided `executor`. (Use ProcessPoolExecutors for actual parallelism.) - `line_length`, `write_back`, `fast`, and `pyi` options are passed to + `write_back`, `fast`, and `mode` options are passed to :func:`format_file_in_place`. """ cache: Cache = {} @@ -503,12 +721,14 @@ async def schedule_formatting( manager = Manager() lock = manager.Lock() tasks = { - loop.run_in_executor( - executor, format_file_in_place, src, fast, mode, write_back, lock + 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.Task] = tasks.keys() + pending: Iterable["asyncio.Future[bool]"] = tasks.keys() try: loop.add_signal_handler(signal.SIGINT, cancel, pending) loop.add_signal_handler(signal.SIGTERM, cancel, pending) @@ -541,7 +761,7 @@ async def schedule_formatting( def format_file_in_place( src: Path, fast: bool, - mode: FileMode, + mode: Mode, write_back: WriteBack = WriteBack.NO, lock: Any = None, # multiprocessing.Manager().Lock() is some crazy proxy ) -> bool: @@ -549,10 +769,10 @@ def format_file_in_place( If `write_back` is DIFF, write a diff to stdout. If it is YES, write reformatted code to the file. - `line_length` and `fast` options are passed to :func:`format_file_contents`. + `mode` and `fast` options are passed to :func:`format_file_contents`. """ if src.suffix == ".pyi": - mode = evolve(mode, is_pyi=True) + mode = replace(mode, is_pyi=True) then = datetime.utcfromtimestamp(src.stat().st_mtime) with open(src, "rb") as buf: @@ -562,33 +782,78 @@ def format_file_in_place( except NothingChanged: return False - if write_back == write_back.YES: + if write_back == WriteBack.YES: with open(src, "w", encoding=encoding, newline=newline) as f: f.write(dst_contents) - elif write_back == write_back.DIFF: + elif write_back in (WriteBack.DIFF, WriteBack.COLOR_DIFF): now = datetime.utcnow() src_name = f"{src}\t{then} +0000" dst_name = f"{src}\t{now} +0000" diff_contents = diff(src_contents, dst_contents, src_name, dst_name) - if lock: - lock.acquire() - try: + + if write_back == write_back.COLOR_DIFF: + diff_contents = color_diff(diff_contents) + + with lock or nullcontext(): f = io.TextIOWrapper( sys.stdout.buffer, encoding=encoding, newline=newline, write_through=True, ) + f = wrap_stream_for_windows(f) f.write(diff_contents) f.detach() - finally: - if lock: - lock.release() + return True +def color_diff(contents: str) -> str: + """Inject the ANSI color codes to the diff.""" + lines = contents.split("\n") + for i, line in enumerate(lines): + if line.startswith("+++") or line.startswith("---"): + line = "\033[1;37m" + line + "\033[0m" # bold white, reset + if line.startswith("@@"): + line = "\033[36m" + line + "\033[0m" # cyan, reset + if line.startswith("+"): + line = "\033[32m" + line + "\033[0m" # green, reset + elif line.startswith("-"): + line = "\033[31m" + line + "\033[0m" # red, reset + lines[i] = line + return "\n".join(lines) + + +def wrap_stream_for_windows( + f: io.TextIOWrapper, +) -> Union[io.TextIOWrapper, "colorama.AnsiToWin32.AnsiToWin32"]: + """ + Wrap the stream in colorama's wrap_stream so colors are shown on Windows. + + If `colorama` is not found, then no change is made. If `colorama` does + exist, then it handles the logic to determine whether or not to change + things. + """ + try: + from colorama import initialise + + # We set `strip=False` so that we can don't have to modify + # test_express_diff_with_color. + f = initialise.wrap_stream( + f, convert=None, strip=False, autoreset=False, wrap=True + ) + + # wrap_stream returns a `colorama.AnsiToWin32.AnsiToWin32` object + # which does not have a `detach()` method. So we fake one. + f.detach = lambda *args, **kwargs: None # type: ignore + except ImportError: + pass + + return f + + def format_stdin_to_stdout( - fast: bool, *, write_back: WriteBack = WriteBack.NO, mode: FileMode + fast: bool, *, write_back: WriteBack = WriteBack.NO, mode: Mode ) -> bool: """Format file on stdin. Return True if changed. @@ -612,22 +877,24 @@ def format_stdin_to_stdout( ) if write_back == WriteBack.YES: f.write(dst) - elif write_back == WriteBack.DIFF: + elif write_back in (WriteBack.DIFF, WriteBack.COLOR_DIFF): now = datetime.utcnow() src_name = f"STDIN\t{then} +0000" dst_name = f"STDOUT\t{now} +0000" - f.write(diff(src, dst, src_name, dst_name)) + d = diff(src, dst, src_name, dst_name) + if write_back == WriteBack.COLOR_DIFF: + d = color_diff(d) + f = wrap_stream_for_windows(f) + f.write(d) f.detach() -def format_file_contents( - src_contents: str, *, fast: bool, mode: FileMode -) -> FileContent: +def format_file_contents(src_contents: str, *, fast: bool, mode: Mode) -> FileContent: """Reformat contents a file and return new contents. If `fast` is False, additionally confirm that the reformatted code is valid by calling :func:`assert_equivalent` and :func:`assert_stable` on it. - `line_length` is passed to :func:`format_str`. + `mode` is passed to :func:`format_str`. """ if src_contents.strip() == "": raise NothingChanged @@ -642,13 +909,37 @@ def format_file_contents( return dst_contents -def format_str(src_contents: str, *, mode: FileMode) -> FileContent: +def format_str(src_contents: str, *, mode: Mode) -> FileContent: """Reformat a string and return new contents. - `line_length` determines how many characters per line are allowed. + `mode` determines formatting options, such as how many characters per line are + allowed. Example: + + >>> import black + >>> print(black.format_str("def f(arg:str='')->None:...", mode=Mode())) + def f(arg: str = "") -> None: + ... + + A more complex example: + >>> print( + ... black.format_str( + ... "def f(arg:str='')->None: hey", + ... mode=black.Mode( + ... target_versions={black.TargetVersion.PY36}, + ... line_length=10, + ... string_normalization=False, + ... is_pyi=False, + ... ), + ... ), + ... ) + def f( + arg: str = '', + ) -> None: + hey + """ src_node = lib2to3_parse(src_contents.lstrip(), mode.target_versions) - dst_contents = "" + dst_contents = [] future_imports = get_future_imports(src_node) if mode.target_versions: versions = mode.target_versions @@ -664,19 +955,23 @@ def format_str(src_contents: str, *, mode: FileMode) -> FileContent: 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 += str(empty_line) + dst_contents.append(str(empty_line) * after) before, after = elt.maybe_empty_lines(current_line) - for _ in range(before): - dst_contents += str(empty_line) - for line in split_line( + dst_contents.append(str(empty_line) * before) + for line in transform_line( current_line, line_length=mode.line_length, - supports_trailing_commas=supports_feature(versions, Feature.TRAILING_COMMA), + normalize_strings=mode.string_normalization, + features=split_line_features, ): - dst_contents += str(line) - return dst_contents + dst_contents.append(str(line)) + return "".join(dst_contents) def decode_bytes(src: bytes) -> Tuple[FileContent, Encoding, NewLine]: @@ -696,24 +991,43 @@ def decode_bytes(src: bytes) -> Tuple[FileContent, Encoding, NewLine]: return tiow.read(), encoding, newline -GRAMMARS = [ - pygram.python_grammar_no_print_statement_no_exec_statement, - pygram.python_grammar_no_print_statement, - pygram.python_grammar, -] - - def get_grammars(target_versions: Set[TargetVersion]) -> List[Grammar]: if not target_versions: - return GRAMMARS - elif all(not version.is_python2() for version in target_versions): - # Python 2-compatible code, so don't try Python 3 grammar. + # 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, ] - else: - return [pygram.python_grammar] + + if all(version.is_python2() for version in target_versions): + # Python 2-only code, so try Python 2 grammars. + return [ + # Python 2.7 with future print_function import + pygram.python_grammar_no_print_statement, + # Python 2.7 + pygram.python_grammar, + ] + + # Python 3-compatible code, so only try Python 3 grammar. + grammars = [] + # If we have to parse both, try to parse async as a keyword first + if not supports_feature(target_versions, Feature.ASYNC_IDENTIFIERS): + # Python 3.7+ + grammars.append( + pygram.python_grammar_no_print_statement_no_exec_statement_async_keywords + ) + if not supports_feature(target_versions, Feature.ASYNC_KEYWORDS): + # Python 3.0-3.6 + grammars.append(pygram.python_grammar_no_print_statement_no_exec_statement) + # At least one of the above branches must have been taken, because every Python + # version has exactly one of the two 'ASYNC_*' flags + return grammars def lib2to3_parse(src_txt: str, target_versions: Iterable[TargetVersion] = ()) -> Node: @@ -749,9 +1063,6 @@ def lib2to3_unparse(node: Node) -> str: return code -T = TypeVar("T") - - class Visitor(Generic[T]): """Basic lib2to3 visitor that yields things of type `T` on `visit()`.""" @@ -768,8 +1079,16 @@ class Visitor(Generic[T]): if node.type < 256: name = token.tok_name[node.type] else: - name = type_repr(node.type) - yield from getattr(self, f"visit_{name}", self.visit_default)(node) + name = str(type_repr(node.type)) + # We explicitly branch on whether a visitor exists (instead of + # using self.visit_default as the default arg to getattr) in order + # to save needing to create a bound method object and so mypyc can + # generate a native call to visit_default. + visitf = getattr(self, f"visit_{name}", None) + if visitf: + yield from visitf(node) + else: + yield from self.visit_default(node) def visit_default(self, node: LN) -> Iterator[T]: """Default `visit_*()` implementation. Recurses to children of `node`.""" @@ -814,8 +1133,8 @@ class DebugVisitor(Visitor[T]): list(v.visit(code)) -WHITESPACE = {token.DEDENT, token.INDENT, token.NEWLINE} -STATEMENT = { +WHITESPACE: Final = {token.DEDENT, token.INDENT, token.NEWLINE} +STATEMENT: Final = { syms.if_stmt, syms.while_stmt, syms.for_stmt, @@ -825,10 +1144,10 @@ STATEMENT = { syms.funcdef, syms.classdef, } -STANDALONE_COMMENT = 153 +STANDALONE_COMMENT: Final = 153 token.tok_name[STANDALONE_COMMENT] = "STANDALONE_COMMENT" -LOGIC_OPERATORS = {"and", "or"} -COMPARATORS = { +LOGIC_OPERATORS: Final = {"and", "or"} +COMPARATORS: Final = { token.LESS, token.GREATER, token.EQEQUAL, @@ -836,7 +1155,7 @@ COMPARATORS = { token.LESSEQUAL, token.GREATEREQUAL, } -MATH_OPERATORS = { +MATH_OPERATORS: Final = { token.VBAR, token.CIRCUMFLEX, token.AMPER, @@ -852,22 +1171,23 @@ MATH_OPERATORS = { token.TILDE, token.DOUBLESTAR, } -STARS = {token.STAR, token.DOUBLESTAR} -VARARGS_PARENTS = { +STARS: Final = {token.STAR, token.DOUBLESTAR} +VARARGS_SPECIALS: Final = STARS | {token.SLASH} +VARARGS_PARENTS: Final = { syms.arglist, syms.argument, # double star in arglist syms.trailer, # single argument to call syms.typedargslist, syms.varargslist, # lambdas } -UNPACKING_PARENTS = { +UNPACKING_PARENTS: Final = { syms.atom, # single element of a list or set literal syms.dictsetmaker, syms.listmaker, syms.testlist_gexp, syms.testlist_star_expr, } -TEST_DESCENDANTS = { +TEST_DESCENDANTS: Final = { syms.test, syms.lambdef, syms.or_test, @@ -884,7 +1204,7 @@ TEST_DESCENDANTS = { syms.term, syms.power, } -ASSIGNMENTS = { +ASSIGNMENTS: Final = { "=", "+=", "-=", @@ -900,13 +1220,13 @@ ASSIGNMENTS = { "**=", "//=", } -COMPREHENSION_PRIORITY = 20 -COMMA_PRIORITY = 18 -TERNARY_PRIORITY = 16 -LOGIC_PRIORITY = 14 -STRING_PRIORITY = 12 -COMPARATOR_PRIORITY = 10 -MATH_PRIORITIES = { +COMPREHENSION_PRIORITY: Final = 20 +COMMA_PRIORITY: Final = 18 +TERNARY_PRIORITY: Final = 16 +LOGIC_PRIORITY: Final = 14 +STRING_PRIORITY: Final = 12 +COMPARATOR_PRIORITY: Final = 10 +MATH_PRIORITIES: Final = { token.VBAR: 9, token.CIRCUMFLEX: 8, token.AMPER: 7, @@ -922,7 +1242,7 @@ MATH_PRIORITIES = { token.TILDE: 3, token.DOUBLESTAR: 2, } -DOT_PRIORITY = 1 +DOT_PRIORITY: Final = 1 @dataclass @@ -930,11 +1250,11 @@ 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) + bracket_match: Dict[Tuple[Depth, NodeType], Leaf] = field(default_factory=dict) + delimiters: Dict[LeafID, Priority] = field(default_factory=dict) previous: Optional[Leaf] = None - _for_loop_depths: List[int] = Factory(list) - _lambda_argument_depths: List[int] = Factory(list) + _for_loop_depths: List[int] = field(default_factory=list) + _lambda_argument_depths: List[int] = field(default_factory=list) def mark(self, leaf: Leaf) -> None: """Mark `leaf` with bracket-related metadata. Keep track of delimiters. @@ -980,7 +1300,7 @@ class BracketTracker: """Return True if there is an yet unmatched open bracket on the line.""" return bool(self.bracket_match) - def max_delimiter_priority(self, exclude: Iterable[LeafID] = ()) -> int: + 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. @@ -988,7 +1308,7 @@ class BracketTracker: """ return max(v for k, v in self.delimiters.items() if k not in exclude) - def delimiter_count_with_priority(self, priority: int = 0) -> int: + 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. @@ -1062,11 +1382,10 @@ class Line: """Holds leaves and comments. Can be printed with `str(line)`.""" depth: int = 0 - leaves: List[Leaf] = Factory(list) - # The LeafID keys of comments must remain ordered by the corresponding leaf's index - # in leaves - comments: Dict[LeafID, List[Leaf]] = Factory(dict) - bracket_tracker: BracketTracker = Factory(BracketTracker) + leaves: List[Leaf] = field(default_factory=list) + # keys ordered like `leaves` + comments: Dict[LeafID, List[Leaf]] = field(default_factory=dict) + bracket_tracker: BracketTracker = field(default_factory=BracketTracker) inside_brackets: bool = False should_explode: bool = False @@ -1146,6 +1465,69 @@ class Line: 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.)""" @@ -1193,72 +1575,117 @@ class Line: def contains_standalone_comments(self, depth_limit: int = sys.maxsize) -> bool: """If so, needs to be split before emitting.""" for leaf in self.leaves: - if leaf.type == STANDALONE_COMMENT: - if leaf.bracket_depth <= depth_limit: - return True + if leaf.type == STANDALONE_COMMENT and leaf.bracket_depth <= depth_limit: + return True return False - def contains_multiline_strings(self) -> bool: - for leaf in self.leaves: - if is_multiline_string(leaf): - return True + 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 comment_seen or ( + not is_type_comment(comment, " ignore") + and leaf_id not in ignored_ids + ): + return True + + comment_seen = True + + return False + + def contains_unsplittable_type_ignore(self) -> bool: + if not self.leaves: + return False + + # If a 'type: ignore' is attached to the end of a line, we + # can't split the line, because we can't know which of the + # subexpressions the ignore was meant to apply to. + # + # We only want this to apply to actual physical lines from the + # original source, though: we don't want the presence of a + # 'type: ignore' at the end of a multiline expression to + # justify pushing it all onto one line. Thus we + # (unfortunately) need to check the actual source lines and + # only report an unsplittable 'type: ignore' if this line was + # one line in the original code. + + # Grab the first and last line numbers, skipping generated leaves + first_line = next((l.lineno for l in self.leaves if l.lineno != 0), 0) + last_line = next((l.lineno for l in reversed(self.leaves) if l.lineno != 0), 0) + + if first_line == last_line: + # We look at the last two leaves since a comma or an + # invisible paren could have been added at the end of the + # line. + for node in self.leaves[-2:]: + for comment in self.comments.get(id(node), []): + if is_type_comment(comment, " ignore"): + return True return False + def contains_multiline_strings(self) -> bool: + return any(is_multiline_string(leaf) for leaf in self.leaves) + def maybe_remove_trailing_comma(self, closing: Leaf) -> bool: """Remove trailing comma if there is one and it's safe.""" + if not (self.leaves and self.leaves[-1].type == token.COMMA): + return False + + # We remove trailing commas only in the case of importing a + # single name from a module. if not ( self.leaves + and self.is_import + and len(self.leaves) > 4 and self.leaves[-1].type == token.COMMA and closing.type in CLOSING_BRACKETS + and self.leaves[-4].type == token.NAME + and ( + # regular `from foo import bar,` + self.leaves[-4].value == "import" + # `from foo import (bar as baz,) + or ( + len(self.leaves) > 6 + and self.leaves[-6].value == "import" + and self.leaves[-3].value == "as" + ) + # `from foo import bar as baz,` + or ( + len(self.leaves) > 5 + and self.leaves[-5].value == "import" + and self.leaves[-3].value == "as" + ) + ) + and closing.type == token.RPAR ): return False - if closing.type == token.RBRACE: - self.remove_trailing_comma() - return True - - if closing.type == token.RSQB: - comma = self.leaves[-1] - if comma.parent and comma.parent.type == syms.listmaker: - self.remove_trailing_comma() - return True - - # For parens let's check if it's safe to remove the comma. - # Imports are always safe. - if self.is_import: - self.remove_trailing_comma() - return True - - # Otherwise, if the trailing one is the only one, we might mistakenly - # change a tuple into a different type by removing the comma. - depth = closing.bracket_depth + 1 - commas = 0 - opening = closing.opening_bracket - for _opening_index, leaf in enumerate(self.leaves): - if leaf is opening: - break - - else: - return False - - for leaf in self.leaves[_opening_index + 1 :]: - if leaf is closing: - break - - bracket_depth = leaf.bracket_depth - if bracket_depth == depth and leaf.type == token.COMMA: - commas += 1 - if leaf.parent and leaf.parent.type == syms.arglist: - commas += 1 - break - - if commas > 1: - self.remove_trailing_comma() - return True - - return False + self.remove_trailing_comma() + return True def append_comment(self, comment: Leaf) -> bool: """Add an inline or standalone comment to the line.""" @@ -1277,13 +1704,25 @@ class Line: comment.prefix = "" return False - else: - leaf_id = id(self.leaves[-1]) - if leaf_id not in self.comments: - self.comments[leaf_id] = [comment] - else: - self.comments[leaf_id].append(comment) - return True + 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`.""" @@ -1291,17 +1730,11 @@ class Line: def remove_trailing_comma(self) -> None: """Remove the trailing comma and moves the comments attached to it.""" - # Remember, the LeafID keys of self.comments are ordered by the - # corresponding leaf's index in self.leaves - # If id(self.leaves[-2]) is in self.comments, the order doesn't change. - # Otherwise, we insert it into self.comments, and it becomes the last entry. - # However, since we delete id(self.leaves[-1]) from self.comments, the invariant - # is maintained - self.comments.setdefault(id(self.leaves[-2]), []).extend( - self.comments.get(id(self.leaves[-1]), []) + 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 ) - self.comments.pop(id(self.leaves[-1]), None) - self.leaves.pop() def is_complex_subscript(self, leaf: Leaf) -> bool: """Return True iff `leaf` is part of a slice with non-trivial exprs.""" @@ -1321,6 +1754,13 @@ class Line: n.type in TEST_DESCENDANTS for n in subscript_start.pre_order() ) + def clone(self) -> "Line": + return Line( + depth=self.depth, + inside_brackets=self.inside_brackets, + should_explode=self.should_explode, + ) + def __str__(self) -> str: """Render the line.""" if not self: @@ -1334,6 +1774,7 @@ class Line: res += str(leaf) for comment in itertools.chain.from_iterable(self.comments.values()): res += str(comment) + return res + "\n" def __bool__(self) -> bool: @@ -1354,7 +1795,7 @@ class EmptyLineTracker: is_pyi: bool = False previous_line: Optional[Line] = None previous_after: int = 0 - previous_defs: List[int] = Factory(list) + previous_defs: List[int] = field(default_factory=list) def maybe_empty_lines(self, current_line: Line) -> Tuple[int, int]: """Return the number of extra empty lines before and after the `current_line`. @@ -1363,7 +1804,13 @@ class EmptyLineTracker: lines (two on module-level). """ before, after = self._maybe_empty_lines(current_line) - before -= self.previous_after + before = ( + # Black should not insert empty lines at the beginning + # of the file + 0 + if self.previous_line is None + else before - self.previous_after + ) self.previous_after = after self.previous_line = current_line return before, after @@ -1462,7 +1909,7 @@ class LineGenerator(Visitor[Line]): is_pyi: bool = False normalize_strings: bool = True - current_line: Line = Factory(Line) + current_line: Line = field(default_factory=Line) remove_u_prefix: bool = False def line(self, indent: int = 0) -> Iterator[Line]: @@ -1511,13 +1958,13 @@ class LineGenerator(Visitor[Line]): self.current_line.append(node) yield from super().visit_default(node) - def visit_INDENT(self, node: Node) -> Iterator[Line]: + def visit_INDENT(self, node: Leaf) -> Iterator[Line]: """Increase indentation level, maybe yield a line.""" # In blib2to3 INDENT never holds comments. yield from self.line(+1) yield from self.visit_default(node) - def visit_DEDENT(self, node: Node) -> Iterator[Line]: + def visit_DEDENT(self, node: Leaf) -> Iterator[Line]: """Decrease indentation level, maybe yield a line.""" # The current line might still wait for trailing comments. At DEDENT time # there won't be any (they would be prefixes on the preceding NEWLINE). @@ -1610,7 +2057,36 @@ class LineGenerator(Visitor[Line]): yield from self.line() yield from self.visit_default(leaf) - def __attrs_post_init__(self) -> None: + def visit_factor(self, node: Node) -> Iterator[Line]: + """Force parentheses between a unary op and a binary power: + + -2 ** 8 -> -(2 ** 8) + """ + _operator, operand = node.children + if ( + operand.type == syms.power + and len(operand.children) == 3 + and operand.children[1].type == token.DOUBLESTAR + ): + lpar = Leaf(token.LPAR, "(") + rpar = Leaf(token.RPAR, ")") + index = operand.remove() or 0 + node.insert_child(index, Node(syms.atom, [lpar, operand, rpar])) + yield from self.visit_default(node) + + def visit_STRING(self, leaf: Leaf) -> Iterator[Line]: + # Check if it's a docstring + if prev_siblings_are( + leaf.parent, [None, token.NEWLINE, token.INDENT, syms.simple_stmt] + ) and is_multiline_string(leaf): + prefix = " " * self.current_line.depth + docstring = fix_docstring(leaf.value[3:-3], prefix) + leaf.value = leaf.value[0:3] + docstring + leaf.value[-3:] + normalize_string_quotes(leaf) + + yield from self.visit_default(leaf) + + def __post_init__(self) -> None: """You are in a twisty little maze of passages.""" v = self.visit_stmt Ø: Set[str] = set() @@ -1700,7 +2176,7 @@ def whitespace(leaf: Leaf, *, complex_subscript: bool) -> str: # noqa: C901 # that, too. return prevp.prefix - elif prevp.type in STARS: + elif prevp.type in VARARGS_SPECIALS: if is_vararg(prevp, within=VARARGS_PARENTS | UNPACKING_PARENTS): return NO @@ -1790,7 +2266,7 @@ def whitespace(leaf: Leaf, *, complex_subscript: bool) -> str: # noqa: C901 if not prevp or prevp.type == token.LPAR: return NO - elif prev.type in {token.EQUAL} | STARS: + elif prev.type in {token.EQUAL} | VARARGS_SPECIALS: return NO elif p.type == syms.decorator: @@ -1891,6 +2367,22 @@ def preceding_leaf(node: Optional[LN]) -> Optional[Leaf]: return None +def prev_siblings_are(node: Optional[LN], tokens: List[Optional[NodeType]]) -> bool: + """Return if the `node` and its previous siblings match types against the provided + list of tokens; the provided `node`has its type matched against the last element in + the list. `None` can be used as the first element to declare that the start of the + list is anchored at the start of its parent's children.""" + if not tokens: + return True + if tokens[-1] is None: + return node is None + if not node: + return False + if node.type != tokens[-1]: + return False + return prev_siblings_are(node.prev_sibling, tokens[:-1]) + + def child_towards(ancestor: Node, descendant: LN) -> Optional[LN]: """Return the child of `ancestor` that contains `descendant`.""" node: Optional[LN] = descendant @@ -1924,7 +2416,7 @@ def container_of(leaf: Leaf) -> LN: return container -def is_split_after_delimiter(leaf: Leaf, previous: Optional[Leaf] = None) -> int: +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 @@ -1938,7 +2430,7 @@ def is_split_after_delimiter(leaf: Leaf, previous: Optional[Leaf] = None) -> int return 0 -def is_split_before_delimiter(leaf: Leaf, previous: Optional[Leaf] = None) -> int: +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 @@ -2088,15 +2580,21 @@ def list_comments(prefix: str, *, is_endmarker: bool) -> List[ProtoComment]: 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 == 0 and not is_endmarker: + if index == ignored_lines and not is_endmarker: comment_type = token.COMMENT # simple trailing comment else: comment_type = STANDALONE_COMMENT @@ -2129,55 +2627,53 @@ def make_comment(content: str) -> str: return "#" + content -def split_line( +def transform_line( line: Line, line_length: int, - inner: bool = False, - supports_trailing_commas: bool = False, + normalize_strings: bool, + features: Collection[Feature] = (), ) -> Iterator[Line]: - """Split a `line` into potentially many lines. + """Transform a `line`, potentially splitting it into many lines. They should fit in the allotted `line_length` but might not be able to. - `inner` signifies that there were a pair of brackets somewhere around the - current `line`, possibly transitively. This means we can fallback to splitting - by delimiters if the LHS/RHS don't yield any results. - If `supports_trailing_commas` is True, splitting may use the TRAILING_COMMA feature. + `features` are syntactical features that may be used in the output. """ if line.is_comment: yield line return - line_str = str(line).strip("\n") + line_str = line_to_string(line) - # we don't want to split special comments like type annotations - # https://github.com/python/typing/issues/186 - has_special_comment = False - for leaf in line.leaves: - for comment in line.comments_after(leaf): - if leaf.type == token.COMMA and is_special_comment(comment): - has_special_comment = True + def init_st(ST: Type[StringTransformer]) -> StringTransformer: + """Initialize StringTransformer""" + return ST(line_length, normalize_strings) + string_merge = init_st(StringMerger) + string_paren_strip = init_st(StringParenStripper) + string_split = init_st(StringSplitter) + string_paren_wrap = init_st(StringParenWrapper) + + transformers: List[Transformer] if ( - not has_special_comment + not line.contains_uncollapsable_type_comments() and not line.should_explode - and is_line_short_enough(line, line_length=line_length, line_str=line_str) + and not line.is_collection_with_optional_trailing_comma + and ( + is_line_short_enough(line, line_length=line_length, line_str=line_str) + or line.contains_unsplittable_type_ignore() + ) + and not (line.contains_standalone_comments() and line.inside_brackets) ): - yield line - return - - split_funcs: List[SplitFunc] - if line.is_def: - split_funcs = [left_hand_split] + # Only apply basic string preprocessing, since lines shouldn't be split here. + transformers = [string_merge, string_paren_strip] + elif line.is_def: + transformers = [left_hand_split] else: - def rhs(line: Line, supports_trailing_commas: bool = False) -> Iterator[Line]: + 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, supports_trailing_commas, omit=omit - ) - ) + 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 @@ -2185,33 +2681,51 @@ def split_line( # All splits failed, best effort split with no omits. # This mostly happens to multiline strings that are by definition # reported as not fitting a single line. - yield from right_hand_split(line, supports_trailing_commas) + # line_length=1 here was historically a bug that somehow became a feature. + # See #762 and #781 for the full story. + yield from right_hand_split(line, line_length=1, features=features) if line.inside_brackets: - split_funcs = [delimiter_split, standalone_comment_split, rhs] + transformers = [ + string_merge, + string_paren_strip, + delimiter_split, + standalone_comment_split, + string_split, + string_paren_wrap, + rhs, + ] else: - split_funcs = [rhs] - for split_func in split_funcs: + transformers = [ + string_merge, + string_paren_strip, + string_split, + string_paren_wrap, + rhs, + ] + + for transform in transformers: # We are accumulating lines in `result` because we might want to abort # mission and return the original line in the end, or attempt a different # split altogether. result: List[Line] = [] try: - for l in split_func(line, supports_trailing_commas): + for l in transform(line, features): if str(l).strip("\n") == line_str: - raise CannotSplit("Split function returned an unchanged result") + raise CannotTransform( + "Line transformer returned an unchanged result" + ) result.extend( - split_line( + transform_line( l, line_length=line_length, - inner=True, - supports_trailing_commas=supports_trailing_commas, + normalize_strings=normalize_strings, + features=features, ) ) - except CannotSplit: + except CannotTransform: continue - else: yield from result break @@ -2220,20 +2734,1949 @@ def split_line( yield line -def left_hand_split( - line: Line, supports_trailing_commas: bool = False -) -> Iterator[Line]: - """Split line into many lines, starting with the first matching bracket pair. +@dataclass # type: ignore +class StringTransformer(ABC): + """ + An implementation of the Transformer protocol that relies on its + subclasses overriding the template methods `do_match(...)` and + `do_transform(...)`. - Note: this usually looks weird, only use this for function definitions. - Prefer RHS otherwise. This is why this function is not symmetrical with + This Transformer works exclusively on strings (for example, by merging + or splitting them). + + The following sections can be found among the docstrings of each concrete + StringTransformer subclass. + + Requirements: + Which requirements must be met of the given Line for this + StringTransformer to be applied? + + Transformations: + If the given Line meets all of the above requirments, which string + transformations can you expect to be applied to it by this + StringTransformer? + + Collaborations: + What contractual agreements does this StringTransformer have with other + StringTransfomers? Such collaborations should be eliminated/minimized + as much as possible. + """ + + line_length: int + normalize_strings: bool + + @abstractmethod + def do_match(self, line: Line) -> TMatchResult: + """ + Returns: + * Ok(string_idx) such that `line.leaves[string_idx]` is our target + string, if a match was able to be made. + OR + * Err(CannotTransform), if a match was not able to be made. + """ + + @abstractmethod + def do_transform(self, line: Line, string_idx: int) -> Iterator[TResult[Line]]: + """ + Yields: + * Ok(new_line) where new_line is the new transformed line. + OR + * Err(CannotTransform) if the transformation failed for some reason. The + `do_match(...)` template method should usually be used to reject + the form of the given Line, but in some cases it is difficult to + know whether or not a Line meets the StringTransformer's + requirements until the transformation is already midway. + + Side Effects: + This method should NOT mutate @line directly, but it MAY mutate the + Line's underlying Node structure. (WARNING: If the underlying Node + structure IS altered, then this method should NOT be allowed to + yield an CannotTransform after that point.) + """ + + def __call__(self, line: Line, _features: Collection[Feature]) -> Iterator[Line]: + """ + StringTransformer instances have a call signature that mirrors that of + the Transformer type. + + Raises: + CannotTransform(...) if the concrete StringTransformer class is unable + to transform @line. + """ + # Optimization to avoid calling `self.do_match(...)` when the line does + # not contain any string. + if not any(leaf.type == token.STRING for leaf in line.leaves): + raise CannotTransform("There are no strings in this line.") + + match_result = self.do_match(line) + + if isinstance(match_result, Err): + cant_transform = match_result.err() + raise CannotTransform( + f"The string transformer {self.__class__.__name__} does not recognize" + " this line as one that it can transform." + ) from cant_transform + + string_idx = match_result.ok() + + for line_result in self.do_transform(line, string_idx): + if isinstance(line_result, Err): + cant_transform = line_result.err() + raise CannotTransform( + "StringTransformer failed while attempting to transform string." + ) from cant_transform + line = line_result.ok() + yield line + + +@dataclass +class CustomSplit: + """A custom (i.e. manual) string split. + + A single CustomSplit instance represents a single substring. + + Examples: + Consider the following string: + ``` + "Hi there friend." + " This is a custom" + f" string {split}." + ``` + + This string will correspond to the following three CustomSplit instances: + ``` + CustomSplit(False, 16) + CustomSplit(False, 17) + CustomSplit(True, 16) + ``` + """ + + has_prefix: bool + break_idx: int + + +class CustomSplitMapMixin: + """ + This mixin class is used to map merged strings to a sequence of + CustomSplits, which will then be used to re-split the strings iff none of + the resultant substrings go over the configured max line length. + """ + + _Key = Tuple[StringID, str] + _CUSTOM_SPLIT_MAP: Dict[_Key, Tuple[CustomSplit, ...]] = defaultdict(tuple) + + @staticmethod + def _get_key(string: str) -> "CustomSplitMapMixin._Key": + """ + Returns: + A unique identifier that is used internally to map @string to a + group of custom splits. + """ + return (id(string), string) + + def add_custom_splits( + self, string: str, custom_splits: Iterable[CustomSplit] + ) -> None: + """Custom Split Map Setter Method + + Side Effects: + Adds a mapping from @string to the custom splits @custom_splits. + """ + key = self._get_key(string) + self._CUSTOM_SPLIT_MAP[key] = tuple(custom_splits) + + def pop_custom_splits(self, string: str) -> List[CustomSplit]: + """Custom Split Map Getter Method + + Returns: + * A list of the custom splits that are mapped to @string, if any + exist. + OR + * [], otherwise. + + Side Effects: + Deletes the mapping between @string and its associated custom + splits (which are returned to the caller). + """ + key = self._get_key(string) + + custom_splits = self._CUSTOM_SPLIT_MAP[key] + del self._CUSTOM_SPLIT_MAP[key] + + return list(custom_splits) + + def has_custom_splits(self, string: str) -> bool: + """ + Returns: + True iff @string is associated with a set of custom splits. + """ + key = self._get_key(string) + return key in self._CUSTOM_SPLIT_MAP + + +class StringMerger(CustomSplitMapMixin, StringTransformer): + """StringTransformer that merges strings together. + + Requirements: + (A) The line contains adjacent strings such that at most one substring + has inline comments AND none of those inline comments are pragmas AND + the set of all substring prefixes is either of length 1 or equal to + {"", "f"} AND none of the substrings are raw strings (i.e. are prefixed + with 'r'). + OR + (B) The line contains a string which uses line continuation backslashes. + + Transformations: + Depending on which of the two requirements above where met, either: + + (A) The string group associated with the target string is merged. + OR + (B) All line-continuation backslashes are removed from the target string. + + Collaborations: + StringMerger provides custom split information to StringSplitter. + """ + + def do_match(self, line: Line) -> TMatchResult: + LL = line.leaves + + is_valid_index = is_valid_index_factory(LL) + + for (i, leaf) in enumerate(LL): + if ( + leaf.type == token.STRING + and is_valid_index(i + 1) + and LL[i + 1].type == token.STRING + ): + return Ok(i) + + if leaf.type == token.STRING and "\\\n" in leaf.value: + return Ok(i) + + return TErr("This line has no strings that need merging.") + + def do_transform(self, line: Line, string_idx: int) -> Iterator[TResult[Line]]: + new_line = line + rblc_result = self.__remove_backslash_line_continuation_chars( + new_line, string_idx + ) + if isinstance(rblc_result, Ok): + new_line = rblc_result.ok() + + msg_result = self.__merge_string_group(new_line, string_idx) + if isinstance(msg_result, Ok): + new_line = msg_result.ok() + + if isinstance(rblc_result, Err) and isinstance(msg_result, Err): + msg_cant_transform = msg_result.err() + rblc_cant_transform = rblc_result.err() + cant_transform = CannotTransform( + "StringMerger failed to merge any strings in this line." + ) + + # Chain the errors together using `__cause__`. + msg_cant_transform.__cause__ = rblc_cant_transform + cant_transform.__cause__ = msg_cant_transform + + yield Err(cant_transform) + else: + yield Ok(new_line) + + @staticmethod + def __remove_backslash_line_continuation_chars( + line: Line, string_idx: int + ) -> TResult[Line]: + """ + Merge strings that were split across multiple lines using + line-continuation backslashes. + + Returns: + Ok(new_line), if @line contains backslash line-continuation + characters. + OR + Err(CannotTransform), otherwise. + """ + LL = line.leaves + + string_leaf = LL[string_idx] + if not ( + string_leaf.type == token.STRING + and "\\\n" in string_leaf.value + and not has_triple_quotes(string_leaf.value) + ): + return TErr( + f"String leaf {string_leaf} does not contain any backslash line" + " continuation characters." + ) + + new_line = line.clone() + new_line.comments = line.comments + append_leaves(new_line, line, LL) + + new_string_leaf = new_line.leaves[string_idx] + new_string_leaf.value = new_string_leaf.value.replace("\\\n", "") + + return Ok(new_line) + + def __merge_string_group(self, line: Line, string_idx: int) -> TResult[Line]: + """ + Merges string group (i.e. set of adjacent strings) where the first + string in the group is `line.leaves[string_idx]`. + + Returns: + Ok(new_line), if ALL of the validation checks found in + __validate_msg(...) pass. + OR + Err(CannotTransform), otherwise. + """ + LL = line.leaves + + is_valid_index = is_valid_index_factory(LL) + + vresult = self.__validate_msg(line, string_idx) + if isinstance(vresult, Err): + return vresult + + # If the string group is wrapped inside an Atom node, we must make sure + # to later replace that Atom with our new (merged) string leaf. + atom_node = LL[string_idx].parent + + # We will place BREAK_MARK in between every two substrings that we + # merge. We will then later go through our final result and use the + # various instances of BREAK_MARK we find to add the right values to + # the custom split map. + BREAK_MARK = "@@@@@ BLACK BREAKPOINT MARKER @@@@@" + + QUOTE = LL[string_idx].value[-1] + + def make_naked(string: str, string_prefix: str) -> str: + """Strip @string (i.e. make it a "naked" string) + + Pre-conditions: + * assert_is_leaf_string(@string) + + Returns: + A string that is identical to @string except that + @string_prefix has been stripped, the surrounding QUOTE + characters have been removed, and any remaining QUOTE + characters have been escaped. + """ + assert_is_leaf_string(string) + + RE_EVEN_BACKSLASHES = r"(?:(?= 0 + ), "Logic error while filling the custom string breakpoint cache." + + temp_string = temp_string[mark_idx + len(BREAK_MARK) :] + breakpoint_idx = mark_idx + (len(prefix) if has_prefix else 0) + 1 + custom_splits.append(CustomSplit(has_prefix, breakpoint_idx)) + + string_leaf = Leaf(token.STRING, S_leaf.value.replace(BREAK_MARK, "")) + + if atom_node is not None: + replace_child(atom_node, string_leaf) + + # Build the final line ('new_line') that this method will later return. + new_line = line.clone() + for (i, leaf) in enumerate(LL): + if i == string_idx: + new_line.append(string_leaf) + + if string_idx <= i < string_idx + num_of_strings: + for comment_leaf in line.comments_after(LL[i]): + new_line.append(comment_leaf, preformatted=True) + continue + + append_leaves(new_line, line, [leaf]) + + self.add_custom_splits(string_leaf.value, custom_splits) + return Ok(new_line) + + @staticmethod + def __validate_msg(line: Line, string_idx: int) -> TResult[None]: + """Validate (M)erge (S)tring (G)roup + + Transform-time string validation logic for __merge_string_group(...). + + Returns: + * Ok(None), if ALL validation checks (listed below) pass. + OR + * Err(CannotTransform), if any of the following are true: + - The target string is not in a string group (i.e. it has no + adjacent strings). + - The string group has more than one inline comment. + - The string group has an inline comment that appears to be a pragma. + - The set of all string prefixes in the string group is of + length greater than one and is not equal to {"", "f"}. + - The string group consists of raw strings. + """ + num_of_inline_string_comments = 0 + set_of_prefixes = set() + num_of_strings = 0 + for leaf in line.leaves[string_idx:]: + if leaf.type != token.STRING: + # If the string group is trailed by a comma, we count the + # comments trailing the comma to be one of the string group's + # comments. + if leaf.type == token.COMMA and id(leaf) in line.comments: + num_of_inline_string_comments += 1 + break + + if has_triple_quotes(leaf.value): + return TErr("StringMerger does NOT merge multiline strings.") + + num_of_strings += 1 + prefix = get_string_prefix(leaf.value) + if "r" in prefix: + return TErr("StringMerger does NOT merge raw strings.") + + set_of_prefixes.add(prefix) + + if id(leaf) in line.comments: + num_of_inline_string_comments += 1 + if contains_pragma_comment(line.comments[id(leaf)]): + return TErr("Cannot merge strings which have pragma comments.") + + if num_of_strings < 2: + return TErr( + f"Not enough strings to merge (num_of_strings={num_of_strings})." + ) + + if num_of_inline_string_comments > 1: + return TErr( + f"Too many inline string comments ({num_of_inline_string_comments})." + ) + + if len(set_of_prefixes) > 1 and set_of_prefixes != {"", "f"}: + return TErr(f"Too many different prefixes ({set_of_prefixes}).") + + return Ok(None) + + +class StringParenStripper(StringTransformer): + """StringTransformer that strips surrounding parentheses from strings. + + Requirements: + The line contains a string which is surrounded by parentheses and: + - The target string is NOT the only argument to a function call). + - The RPAR is NOT followed by an attribute access (i.e. a dot). + + Transformations: + The parentheses mentioned in the 'Requirements' section are stripped. + + Collaborations: + StringParenStripper has its own inherent usefulness, but it is also + relied on to clean up the parentheses created by StringParenWrapper (in + the event that they are no longer needed). + """ + + def do_match(self, line: Line) -> TMatchResult: + LL = line.leaves + + is_valid_index = is_valid_index_factory(LL) + + for (idx, leaf) in enumerate(LL): + # Should be a string... + if leaf.type != token.STRING: + continue + + # Should be preceded by a non-empty LPAR... + if ( + not is_valid_index(idx - 1) + or LL[idx - 1].type != token.LPAR + or is_empty_lpar(LL[idx - 1]) + ): + continue + + # That LPAR should NOT be preceded by a function name or a closing + # bracket (which could be a function which returns a function or a + # list/dictionary that contains a function)... + if is_valid_index(idx - 2) and ( + LL[idx - 2].type == token.NAME or LL[idx - 2].type in CLOSING_BRACKETS + ): + continue + + string_idx = idx + + # Skip the string trailer, if one exists. + string_parser = StringParser() + next_idx = string_parser.parse(LL, string_idx) + + # Should be followed by a non-empty RPAR... + if ( + is_valid_index(next_idx) + and LL[next_idx].type == token.RPAR + and not is_empty_rpar(LL[next_idx]) + ): + # That RPAR should NOT be followed by a '.' symbol. + if is_valid_index(next_idx + 1) and LL[next_idx + 1].type == token.DOT: + continue + + return Ok(string_idx) + + return TErr("This line has no strings wrapped in parens.") + + def do_transform(self, line: Line, string_idx: int) -> Iterator[TResult[Line]]: + LL = line.leaves + + string_parser = StringParser() + rpar_idx = string_parser.parse(LL, string_idx) + + for leaf in (LL[string_idx - 1], LL[rpar_idx]): + if line.comments_after(leaf): + yield TErr( + "Will not strip parentheses which have comments attached to them." + ) + + new_line = line.clone() + new_line.comments = line.comments.copy() + + append_leaves(new_line, line, LL[: string_idx - 1]) + + string_leaf = Leaf(token.STRING, LL[string_idx].value) + LL[string_idx - 1].remove() + replace_child(LL[string_idx], string_leaf) + new_line.append(string_leaf) + + append_leaves( + new_line, line, LL[string_idx + 1 : rpar_idx] + LL[rpar_idx + 1 :], + ) + + LL[rpar_idx].remove() + + yield Ok(new_line) + + +class BaseStringSplitter(StringTransformer): + """ + Abstract class for StringTransformers which transform a Line's strings by splitting + them or placing them on their own lines where necessary to avoid going over + the configured line length. + + Requirements: + * The target string value is responsible for the line going over the + line length limit. It follows that after all of black's other line + split methods have been exhausted, this line (or one of the resulting + lines after all line splits are performed) would still be over the + line_length limit unless we split this string. + AND + * The target string is NOT a "pointless" string (i.e. a string that has + no parent or siblings). + AND + * The target string is not followed by an inline comment that appears + to be a pragma. + AND + * The target string is not a multiline (i.e. triple-quote) string. + """ + + @abstractmethod + def do_splitter_match(self, line: Line) -> TMatchResult: + """ + BaseStringSplitter asks its clients to override this method instead of + `StringTransformer.do_match(...)`. + + Follows the same protocol as `StringTransformer.do_match(...)`. + + Refer to `help(StringTransformer.do_match)` for more information. + """ + + def do_match(self, line: Line) -> TMatchResult: + match_result = self.do_splitter_match(line) + if isinstance(match_result, Err): + return match_result + + string_idx = match_result.ok() + vresult = self.__validate(line, string_idx) + if isinstance(vresult, Err): + return vresult + + return match_result + + def __validate(self, line: Line, string_idx: int) -> TResult[None]: + """ + Checks that @line meets all of the requirements listed in this classes' + docstring. Refer to `help(BaseStringSplitter)` for a detailed + description of those requirements. + + Returns: + * Ok(None), if ALL of the requirements are met. + OR + * Err(CannotTransform), if ANY of the requirements are NOT met. + """ + LL = line.leaves + + string_leaf = LL[string_idx] + + max_string_length = self.__get_max_string_length(line, string_idx) + if len(string_leaf.value) <= max_string_length: + return TErr( + "The string itself is not what is causing this line to be too long." + ) + + if not string_leaf.parent or [L.type for L in string_leaf.parent.children] == [ + token.STRING, + token.NEWLINE, + ]: + return TErr( + f"This string ({string_leaf.value}) appears to be pointless (i.e. has" + " no parent)." + ) + + if id(line.leaves[string_idx]) in line.comments and contains_pragma_comment( + line.comments[id(line.leaves[string_idx])] + ): + return TErr( + "Line appears to end with an inline pragma comment. Splitting the line" + " could modify the pragma's behavior." + ) + + if has_triple_quotes(string_leaf.value): + return TErr("We cannot split multiline strings.") + + return Ok(None) + + def __get_max_string_length(self, line: Line, string_idx: int) -> int: + """ + Calculates the max string length used when attempting to determine + whether or not the target string is responsible for causing the line to + go over the line length limit. + + WARNING: This method is tightly coupled to both StringSplitter and + (especially) StringParenWrapper. There is probably a better way to + accomplish what is being done here. + + Returns: + max_string_length: such that `line.leaves[string_idx].value > + max_string_length` implies that the target string IS responsible + for causing this line to exceed the line length limit. + """ + LL = line.leaves + + is_valid_index = is_valid_index_factory(LL) + + # We use the shorthand "WMA4" in comments to abbreviate "We must + # account for". When giving examples, we use STRING to mean some/any + # valid string. + # + # Finally, we use the following convenience variables: + # + # P: The leaf that is before the target string leaf. + # N: The leaf that is after the target string leaf. + # NN: The leaf that is after N. + + # WMA4 the whitespace at the beginning of the line. + offset = line.depth * 4 + + if is_valid_index(string_idx - 1): + p_idx = string_idx - 1 + if ( + LL[string_idx - 1].type == token.LPAR + and LL[string_idx - 1].value == "" + and string_idx >= 2 + ): + # If the previous leaf is an empty LPAR placeholder, we should skip it. + p_idx -= 1 + + P = LL[p_idx] + if P.type == token.PLUS: + # WMA4 a space and a '+' character (e.g. `+ STRING`). + offset += 2 + + if P.type == token.COMMA: + # WMA4 a space, a comma, and a closing bracket [e.g. `), STRING`]. + offset += 3 + + if P.type in [token.COLON, token.EQUAL, token.NAME]: + # This conditional branch is meant to handle dictionary keys, + # variable assignments, 'return STRING' statement lines, and + # 'else STRING' ternary expression lines. + + # WMA4 a single space. + offset += 1 + + # WMA4 the lengths of any leaves that came before that space. + for leaf in LL[: p_idx + 1]: + offset += len(str(leaf)) + + if is_valid_index(string_idx + 1): + N = LL[string_idx + 1] + if N.type == token.RPAR and N.value == "" and len(LL) > string_idx + 2: + # If the next leaf is an empty RPAR placeholder, we should skip it. + N = LL[string_idx + 2] + + if N.type == token.COMMA: + # WMA4 a single comma at the end of the string (e.g `STRING,`). + offset += 1 + + if is_valid_index(string_idx + 2): + NN = LL[string_idx + 2] + + if N.type == token.DOT and NN.type == token.NAME: + # This conditional branch is meant to handle method calls invoked + # off of a string literal up to and including the LPAR character. + + # WMA4 the '.' character. + offset += 1 + + if ( + is_valid_index(string_idx + 3) + and LL[string_idx + 3].type == token.LPAR + ): + # WMA4 the left parenthesis character. + offset += 1 + + # WMA4 the length of the method's name. + offset += len(NN.value) + + has_comments = False + for comment_leaf in line.comments_after(LL[string_idx]): + if not has_comments: + has_comments = True + # WMA4 two spaces before the '#' character. + offset += 2 + + # WMA4 the length of the inline comment. + offset += len(comment_leaf.value) + + max_string_length = self.line_length - offset + return max_string_length + + +class StringSplitter(CustomSplitMapMixin, BaseStringSplitter): + """ + StringTransformer that splits "atom" strings (i.e. strings which exist on + lines by themselves). + + Requirements: + * The line consists ONLY of a single string (with the exception of a + '+' symbol which MAY exist at the start of the line), MAYBE a string + trailer, and MAYBE a trailing comma. + AND + * All of the requirements listed in BaseStringSplitter's docstring. + + Transformations: + The string mentioned in the 'Requirements' section is split into as + many substrings as necessary to adhere to the configured line length. + + In the final set of substrings, no substring should be smaller than + MIN_SUBSTR_SIZE characters. + + The string will ONLY be split on spaces (i.e. each new substring should + start with a space). + + If the string is an f-string, it will NOT be split in the middle of an + f-expression (e.g. in f"FooBar: {foo() if x else bar()}", {foo() if x + else bar()} is an f-expression). + + If the string that is being split has an associated set of custom split + records and those custom splits will NOT result in any line going over + the configured line length, those custom splits are used. Otherwise the + string is split as late as possible (from left-to-right) while still + adhering to the transformation rules listed above. + + Collaborations: + StringSplitter relies on StringMerger to construct the appropriate + CustomSplit objects and add them to the custom split map. + """ + + MIN_SUBSTR_SIZE = 6 + # Matches an "f-expression" (e.g. {var}) that might be found in an f-string. + RE_FEXPR = r""" + (? TMatchResult: + LL = line.leaves + + is_valid_index = is_valid_index_factory(LL) + + idx = 0 + + # The first leaf MAY be a '+' symbol... + if is_valid_index(idx) and LL[idx].type == token.PLUS: + idx += 1 + + # The next/first leaf MAY be an empty LPAR... + if is_valid_index(idx) and is_empty_lpar(LL[idx]): + idx += 1 + + # The next/first leaf MUST be a string... + if not is_valid_index(idx) or LL[idx].type != token.STRING: + return TErr("Line does not start with a string.") + + string_idx = idx + + # Skip the string trailer, if one exists. + string_parser = StringParser() + idx = string_parser.parse(LL, string_idx) + + # That string MAY be followed by an empty RPAR... + if is_valid_index(idx) and is_empty_rpar(LL[idx]): + idx += 1 + + # That string / empty RPAR leaf MAY be followed by a comma... + if is_valid_index(idx) and LL[idx].type == token.COMMA: + idx += 1 + + # But no more leaves are allowed... + if is_valid_index(idx): + return TErr("This line does not end with a string.") + + return Ok(string_idx) + + def do_transform(self, line: Line, string_idx: int) -> Iterator[TResult[Line]]: + LL = line.leaves + + QUOTE = LL[string_idx].value[-1] + + is_valid_index = is_valid_index_factory(LL) + insert_str_child = insert_str_child_factory(LL[string_idx]) + + prefix = get_string_prefix(LL[string_idx].value) + + # We MAY choose to drop the 'f' prefix from substrings that don't + # contain any f-expressions, but ONLY if the original f-string + # containes at least one f-expression. Otherwise, we will alter the AST + # of the program. + drop_pointless_f_prefix = ("f" in prefix) and re.search( + self.RE_FEXPR, LL[string_idx].value, re.VERBOSE + ) + + first_string_line = True + starts_with_plus = LL[0].type == token.PLUS + + def line_needs_plus() -> bool: + return first_string_line and starts_with_plus + + def maybe_append_plus(new_line: Line) -> None: + """ + Side Effects: + If @line starts with a plus and this is the first line we are + constructing, this function appends a PLUS leaf to @new_line + and replaces the old PLUS leaf in the node structure. Otherwise + this function does nothing. + """ + if line_needs_plus(): + plus_leaf = Leaf(token.PLUS, "+") + replace_child(LL[0], plus_leaf) + new_line.append(plus_leaf) + + ends_with_comma = ( + is_valid_index(string_idx + 1) and LL[string_idx + 1].type == token.COMMA + ) + + def max_last_string() -> int: + """ + Returns: + The max allowed length of the string value used for the last + line we will construct. + """ + result = self.line_length + result -= line.depth * 4 + result -= 1 if ends_with_comma else 0 + result -= 2 if line_needs_plus() else 0 + return result + + # --- Calculate Max Break Index (for string value) + # We start with the line length limit + max_break_idx = self.line_length + # The last index of a string of length N is N-1. + max_break_idx -= 1 + # Leading whitespace is not present in the string value (e.g. Leaf.value). + max_break_idx -= line.depth * 4 + if max_break_idx < 0: + yield TErr( + f"Unable to split {LL[string_idx].value} at such high of a line depth:" + f" {line.depth}" + ) + return + + # Check if StringMerger registered any custom splits. + custom_splits = self.pop_custom_splits(LL[string_idx].value) + # We use them ONLY if none of them would produce lines that exceed the + # line limit. + use_custom_breakpoints = bool( + custom_splits + and all(csplit.break_idx <= max_break_idx for csplit in custom_splits) + ) + + # Temporary storage for the remaining chunk of the string line that + # can't fit onto the line currently being constructed. + rest_value = LL[string_idx].value + + def more_splits_should_be_made() -> bool: + """ + Returns: + True iff `rest_value` (the remaining string value from the last + split), should be split again. + """ + if use_custom_breakpoints: + return len(custom_splits) > 1 + else: + return len(rest_value) > max_last_string() + + string_line_results: List[Ok[Line]] = [] + while more_splits_should_be_made(): + if use_custom_breakpoints: + # Custom User Split (manual) + csplit = custom_splits.pop(0) + break_idx = csplit.break_idx + else: + # Algorithmic Split (automatic) + max_bidx = max_break_idx - 2 if line_needs_plus() else max_break_idx + maybe_break_idx = self.__get_break_idx(rest_value, max_bidx) + if maybe_break_idx is None: + # If we are unable to algorthmically determine a good split + # and this string has custom splits registered to it, we + # fall back to using them--which means we have to start + # over from the beginning. + if custom_splits: + rest_value = LL[string_idx].value + string_line_results = [] + first_string_line = True + use_custom_breakpoints = True + continue + + # Otherwise, we stop splitting here. + break + + break_idx = maybe_break_idx + + # --- Construct `next_value` + next_value = rest_value[:break_idx] + QUOTE + if ( + # Are we allowed to try to drop a pointless 'f' prefix? + drop_pointless_f_prefix + # If we are, will we be successful? + and next_value != self.__normalize_f_string(next_value, prefix) + ): + # If the current custom split did NOT originally use a prefix, + # then `csplit.break_idx` will be off by one after removing + # the 'f' prefix. + break_idx = ( + break_idx + 1 + if use_custom_breakpoints and not csplit.has_prefix + else break_idx + ) + next_value = rest_value[:break_idx] + QUOTE + next_value = self.__normalize_f_string(next_value, prefix) + + # --- Construct `next_leaf` + next_leaf = Leaf(token.STRING, next_value) + insert_str_child(next_leaf) + self.__maybe_normalize_string_quotes(next_leaf) + + # --- Construct `next_line` + next_line = line.clone() + maybe_append_plus(next_line) + next_line.append(next_leaf) + string_line_results.append(Ok(next_line)) + + rest_value = prefix + QUOTE + rest_value[break_idx:] + first_string_line = False + + yield from string_line_results + + if drop_pointless_f_prefix: + rest_value = self.__normalize_f_string(rest_value, prefix) + + rest_leaf = Leaf(token.STRING, rest_value) + insert_str_child(rest_leaf) + + # NOTE: I could not find a test case that verifies that the following + # line is actually necessary, but it seems to be. Otherwise we risk + # not normalizing the last substring, right? + self.__maybe_normalize_string_quotes(rest_leaf) + + last_line = line.clone() + maybe_append_plus(last_line) + + # If there are any leaves to the right of the target string... + if is_valid_index(string_idx + 1): + # We use `temp_value` here to determine how long the last line + # would be if we were to append all the leaves to the right of the + # target string to the last string line. + temp_value = rest_value + for leaf in LL[string_idx + 1 :]: + temp_value += str(leaf) + if leaf.type == token.LPAR: + break + + # Try to fit them all on the same line with the last substring... + if ( + len(temp_value) <= max_last_string() + or LL[string_idx + 1].type == token.COMMA + ): + last_line.append(rest_leaf) + append_leaves(last_line, line, LL[string_idx + 1 :]) + yield Ok(last_line) + # Otherwise, place the last substring on one line and everything + # else on a line below that... + else: + last_line.append(rest_leaf) + yield Ok(last_line) + + non_string_line = line.clone() + append_leaves(non_string_line, line, LL[string_idx + 1 :]) + yield Ok(non_string_line) + # Else the target string was the last leaf... + else: + last_line.append(rest_leaf) + last_line.comments = line.comments.copy() + yield Ok(last_line) + + def __get_break_idx(self, string: str, max_break_idx: int) -> Optional[int]: + """ + This method contains the algorithm that StringSplitter uses to + determine which character to split each string at. + + Args: + @string: The substring that we are attempting to split. + @max_break_idx: The ideal break index. We will return this value if it + meets all the necessary conditions. In the likely event that it + doesn't we will try to find the closest index BELOW @max_break_idx + that does. If that fails, we will expand our search by also + considering all valid indices ABOVE @max_break_idx. + + Pre-Conditions: + * assert_is_leaf_string(@string) + * 0 <= @max_break_idx < len(@string) + + Returns: + break_idx, if an index is able to be found that meets all of the + conditions listed in the 'Transformations' section of this classes' + docstring. + OR + None, otherwise. + """ + is_valid_index = is_valid_index_factory(string) + + assert is_valid_index(max_break_idx) + assert_is_leaf_string(string) + + _fexpr_slices: Optional[List[Tuple[Index, Index]]] = None + + def fexpr_slices() -> Iterator[Tuple[Index, Index]]: + """ + Yields: + All ranges of @string which, if @string were to be split there, + would result in the splitting of an f-expression (which is NOT + allowed). + """ + nonlocal _fexpr_slices + + if _fexpr_slices is None: + _fexpr_slices = [] + for match in re.finditer(self.RE_FEXPR, string, re.VERBOSE): + _fexpr_slices.append(match.span()) + + yield from _fexpr_slices + + is_fstring = "f" in get_string_prefix(string) + + def breaks_fstring_expression(i: Index) -> bool: + """ + Returns: + True iff returning @i would result in the splitting of an + f-expression (which is NOT allowed). + """ + if not is_fstring: + return False + + for (start, end) in fexpr_slices(): + if start <= i < end: + return True + + return False + + def passes_all_checks(i: Index) -> bool: + """ + Returns: + True iff ALL of the conditions listed in the 'Transformations' + section of this classes' docstring would be be met by returning @i. + """ + is_space = string[i] == " " + is_big_enough = ( + len(string[i:]) >= self.MIN_SUBSTR_SIZE + and len(string[:i]) >= self.MIN_SUBSTR_SIZE + ) + return is_space and is_big_enough and not breaks_fstring_expression(i) + + # First, we check all indices BELOW @max_break_idx. + break_idx = max_break_idx + while is_valid_index(break_idx - 1) and not passes_all_checks(break_idx): + break_idx -= 1 + + if not passes_all_checks(break_idx): + # If that fails, we check all indices ABOVE @max_break_idx. + # + # If we are able to find a valid index here, the next line is going + # to be longer than the specified line length, but it's probably + # better than doing nothing at all. + break_idx = max_break_idx + 1 + while is_valid_index(break_idx + 1) and not passes_all_checks(break_idx): + break_idx += 1 + + if not is_valid_index(break_idx) or not passes_all_checks(break_idx): + return None + + return break_idx + + def __maybe_normalize_string_quotes(self, leaf: Leaf) -> None: + if self.normalize_strings: + normalize_string_quotes(leaf) + + def __normalize_f_string(self, string: str, prefix: str) -> str: + """ + Pre-Conditions: + * assert_is_leaf_string(@string) + + Returns: + * If @string is an f-string that contains no f-expressions, we + return a string identical to @string except that the 'f' prefix + has been stripped and all double braces (i.e. '{{' or '}}') have + been normalized (i.e. turned into '{' or '}'). + OR + * Otherwise, we return @string. + """ + assert_is_leaf_string(string) + + if "f" in prefix and not re.search(self.RE_FEXPR, string, re.VERBOSE): + new_prefix = prefix.replace("f", "") + + temp = string[len(prefix) :] + temp = re.sub(r"\{\{", "{", temp) + temp = re.sub(r"\}\}", "}", temp) + new_string = temp + + return f"{new_prefix}{new_string}" + else: + return string + + +class StringParenWrapper(CustomSplitMapMixin, BaseStringSplitter): + """ + StringTransformer that splits non-"atom" strings (i.e. strings that do not + exist on lines by themselves). + + Requirements: + All of the requirements listed in BaseStringSplitter's docstring in + addition to the requirements listed below: + + * The line is a return/yield statement, which returns/yields a string. + OR + * The line is part of a ternary expression (e.g. `x = y if cond else + z`) such that the line starts with `else `, where is + some string. + OR + * The line is an assert statement, which ends with a string. + OR + * The line is an assignment statement (e.g. `x = ` or `x += + `) such that the variable is being assigned the value of some + string. + OR + * The line is a dictionary key assignment where some valid key is being + assigned the value of some string. + + Transformations: + The chosen string is wrapped in parentheses and then split at the LPAR. + + We then have one line which ends with an LPAR and another line that + starts with the chosen string. The latter line is then split again at + the RPAR. This results in the RPAR (and possibly a trailing comma) + being placed on its own line. + + NOTE: If any leaves exist to the right of the chosen string (except + for a trailing comma, which would be placed after the RPAR), those + leaves are placed inside the parentheses. In effect, the chosen + string is not necessarily being "wrapped" by parentheses. We can, + however, count on the LPAR being placed directly before the chosen + string. + + In other words, StringParenWrapper creates "atom" strings. These + can then be split again by StringSplitter, if necessary. + + Collaborations: + In the event that a string line split by StringParenWrapper is + changed such that it no longer needs to be given its own line, + StringParenWrapper relies on StringParenStripper to clean up the + parentheses it created. + """ + + def do_splitter_match(self, line: Line) -> TMatchResult: + LL = line.leaves + + string_idx = None + string_idx = string_idx or self._return_match(LL) + string_idx = string_idx or self._else_match(LL) + string_idx = string_idx or self._assert_match(LL) + string_idx = string_idx or self._assign_match(LL) + string_idx = string_idx or self._dict_match(LL) + + if string_idx is not None: + string_value = line.leaves[string_idx].value + # If the string has no spaces... + if " " not in string_value: + # And will still violate the line length limit when split... + max_string_length = self.line_length - ((line.depth + 1) * 4) + if len(string_value) > max_string_length: + # And has no associated custom splits... + if not self.has_custom_splits(string_value): + # Then we should NOT put this string on its own line. + return TErr( + "We do not wrap long strings in parentheses when the" + " resultant line would still be over the specified line" + " length and can't be split further by StringSplitter." + ) + return Ok(string_idx) + + return TErr("This line does not contain any non-atomic strings.") + + @staticmethod + def _return_match(LL: List[Leaf]) -> Optional[int]: + """ + Returns: + string_idx such that @LL[string_idx] is equal to our target (i.e. + matched) string, if this line matches the return/yield statement + requirements listed in the 'Requirements' section of this classes' + docstring. + OR + None, otherwise. + """ + # If this line is apart of a return/yield statement and the first leaf + # contains either the "return" or "yield" keywords... + if parent_type(LL[0]) in [syms.return_stmt, syms.yield_expr] and LL[ + 0 + ].value in ["return", "yield"]: + is_valid_index = is_valid_index_factory(LL) + + idx = 2 if is_valid_index(1) and is_empty_par(LL[1]) else 1 + # The next visible leaf MUST contain a string... + if is_valid_index(idx) and LL[idx].type == token.STRING: + return idx + + return None + + @staticmethod + def _else_match(LL: List[Leaf]) -> Optional[int]: + """ + Returns: + string_idx such that @LL[string_idx] is equal to our target (i.e. + matched) string, if this line matches the ternary expression + requirements listed in the 'Requirements' section of this classes' + docstring. + OR + None, otherwise. + """ + # If this line is apart of a ternary expression and the first leaf + # contains the "else" keyword... + if ( + parent_type(LL[0]) == syms.test + and LL[0].type == token.NAME + and LL[0].value == "else" + ): + is_valid_index = is_valid_index_factory(LL) + + idx = 2 if is_valid_index(1) and is_empty_par(LL[1]) else 1 + # The next visible leaf MUST contain a string... + if is_valid_index(idx) and LL[idx].type == token.STRING: + return idx + + return None + + @staticmethod + def _assert_match(LL: List[Leaf]) -> Optional[int]: + """ + Returns: + string_idx such that @LL[string_idx] is equal to our target (i.e. + matched) string, if this line matches the assert statement + requirements listed in the 'Requirements' section of this classes' + docstring. + OR + None, otherwise. + """ + # If this line is apart of an assert statement and the first leaf + # contains the "assert" keyword... + if parent_type(LL[0]) == syms.assert_stmt and LL[0].value == "assert": + is_valid_index = is_valid_index_factory(LL) + + for (i, leaf) in enumerate(LL): + # We MUST find a comma... + if leaf.type == token.COMMA: + idx = i + 2 if is_empty_par(LL[i + 1]) else i + 1 + + # That comma MUST be followed by a string... + if is_valid_index(idx) and LL[idx].type == token.STRING: + string_idx = idx + + # Skip the string trailer, if one exists. + string_parser = StringParser() + idx = string_parser.parse(LL, string_idx) + + # But no more leaves are allowed... + if not is_valid_index(idx): + return string_idx + + return None + + @staticmethod + def _assign_match(LL: List[Leaf]) -> Optional[int]: + """ + Returns: + string_idx such that @LL[string_idx] is equal to our target (i.e. + matched) string, if this line matches the assignment statement + requirements listed in the 'Requirements' section of this classes' + docstring. + OR + None, otherwise. + """ + # If this line is apart of an expression statement or is a function + # argument AND the first leaf contains a variable name... + if ( + parent_type(LL[0]) in [syms.expr_stmt, syms.argument, syms.power] + and LL[0].type == token.NAME + ): + is_valid_index = is_valid_index_factory(LL) + + for (i, leaf) in enumerate(LL): + # We MUST find either an '=' or '+=' symbol... + if leaf.type in [token.EQUAL, token.PLUSEQUAL]: + idx = i + 2 if is_empty_par(LL[i + 1]) else i + 1 + + # That symbol MUST be followed by a string... + if is_valid_index(idx) and LL[idx].type == token.STRING: + string_idx = idx + + # Skip the string trailer, if one exists. + string_parser = StringParser() + idx = string_parser.parse(LL, string_idx) + + # The next leaf MAY be a comma iff this line is apart + # of a function argument... + if ( + parent_type(LL[0]) == syms.argument + and is_valid_index(idx) + and LL[idx].type == token.COMMA + ): + idx += 1 + + # But no more leaves are allowed... + if not is_valid_index(idx): + return string_idx + + return None + + @staticmethod + def _dict_match(LL: List[Leaf]) -> Optional[int]: + """ + Returns: + string_idx such that @LL[string_idx] is equal to our target (i.e. + matched) string, if this line matches the dictionary key assignment + statement requirements listed in the 'Requirements' section of this + classes' docstring. + OR + None, otherwise. + """ + # If this line is apart of a dictionary key assignment... + if syms.dictsetmaker in [parent_type(LL[0]), parent_type(LL[0].parent)]: + is_valid_index = is_valid_index_factory(LL) + + for (i, leaf) in enumerate(LL): + # We MUST find a colon... + if leaf.type == token.COLON: + idx = i + 2 if is_empty_par(LL[i + 1]) else i + 1 + + # That colon MUST be followed by a string... + if is_valid_index(idx) and LL[idx].type == token.STRING: + string_idx = idx + + # Skip the string trailer, if one exists. + string_parser = StringParser() + idx = string_parser.parse(LL, string_idx) + + # That string MAY be followed by a comma... + if is_valid_index(idx) and LL[idx].type == token.COMMA: + idx += 1 + + # But no more leaves are allowed... + if not is_valid_index(idx): + return string_idx + + return None + + def do_transform(self, line: Line, string_idx: int) -> Iterator[TResult[Line]]: + LL = line.leaves + + is_valid_index = is_valid_index_factory(LL) + insert_str_child = insert_str_child_factory(LL[string_idx]) + + comma_idx = len(LL) - 1 + ends_with_comma = False + if LL[comma_idx].type == token.COMMA: + ends_with_comma = True + + leaves_to_steal_comments_from = [LL[string_idx]] + if ends_with_comma: + leaves_to_steal_comments_from.append(LL[comma_idx]) + + # --- First Line + first_line = line.clone() + left_leaves = LL[:string_idx] + + # We have to remember to account for (possibly invisible) LPAR and RPAR + # leaves that already wrapped the target string. If these leaves do + # exist, we will replace them with our own LPAR and RPAR leaves. + old_parens_exist = False + if left_leaves and left_leaves[-1].type == token.LPAR: + old_parens_exist = True + leaves_to_steal_comments_from.append(left_leaves[-1]) + left_leaves.pop() + + append_leaves(first_line, line, left_leaves) + + lpar_leaf = Leaf(token.LPAR, "(") + if old_parens_exist: + replace_child(LL[string_idx - 1], lpar_leaf) + else: + insert_str_child(lpar_leaf) + first_line.append(lpar_leaf) + + # We throw inline comments that were originally to the right of the + # target string to the top line. They will now be shown to the right of + # the LPAR. + for leaf in leaves_to_steal_comments_from: + for comment_leaf in line.comments_after(leaf): + first_line.append(comment_leaf, preformatted=True) + + yield Ok(first_line) + + # --- Middle (String) Line + # We only need to yield one (possibly too long) string line, since the + # `StringSplitter` will break it down further if necessary. + string_value = LL[string_idx].value + string_line = Line( + depth=line.depth + 1, + inside_brackets=True, + should_explode=line.should_explode, + ) + string_leaf = Leaf(token.STRING, string_value) + insert_str_child(string_leaf) + string_line.append(string_leaf) + + old_rpar_leaf = None + if is_valid_index(string_idx + 1): + right_leaves = LL[string_idx + 1 :] + if ends_with_comma: + right_leaves.pop() + + if old_parens_exist: + assert ( + right_leaves and right_leaves[-1].type == token.RPAR + ), "Apparently, old parentheses do NOT exist?!" + old_rpar_leaf = right_leaves.pop() + + append_leaves(string_line, line, right_leaves) + + yield Ok(string_line) + + # --- Last Line + last_line = line.clone() + last_line.bracket_tracker = first_line.bracket_tracker + + new_rpar_leaf = Leaf(token.RPAR, ")") + if old_rpar_leaf is not None: + replace_child(old_rpar_leaf, new_rpar_leaf) + else: + insert_str_child(new_rpar_leaf) + last_line.append(new_rpar_leaf) + + # If the target string ended with a comma, we place this comma to the + # right of the RPAR on the last line. + if ends_with_comma: + comma_leaf = Leaf(token.COMMA, ",") + replace_child(LL[comma_idx], comma_leaf) + last_line.append(comma_leaf) + + yield Ok(last_line) + + +class StringParser: + """ + A state machine that aids in parsing a string's "trailer", which can be + either non-existant, an old-style formatting sequence (e.g. `% varX` or `% + (varX, varY)`), or a method-call / attribute access (e.g. `.format(varX, + varY)`). + + NOTE: A new StringParser object MUST be instantiated for each string + trailer we need to parse. + + Examples: + We shall assume that `line` equals the `Line` object that corresponds + to the following line of python code: + ``` + x = "Some {}.".format("String") + some_other_string + ``` + + Furthermore, we will assume that `string_idx` is some index such that: + ``` + assert line.leaves[string_idx].value == "Some {}." + ``` + + The following code snippet then holds: + ``` + string_parser = StringParser() + idx = string_parser.parse(line.leaves, string_idx) + assert line.leaves[idx].type == token.PLUS + ``` + """ + + DEFAULT_TOKEN = -1 + + # String Parser States + START = 1 + DOT = 2 + NAME = 3 + PERCENT = 4 + SINGLE_FMT_ARG = 5 + LPAR = 6 + RPAR = 7 + DONE = 8 + + # Lookup Table for Next State + _goto: Dict[Tuple[ParserState, NodeType], ParserState] = { + # A string trailer may start with '.' OR '%'. + (START, token.DOT): DOT, + (START, token.PERCENT): PERCENT, + (START, DEFAULT_TOKEN): DONE, + # A '.' MUST be followed by an attribute or method name. + (DOT, token.NAME): NAME, + # A method name MUST be followed by an '(', whereas an attribute name + # is the last symbol in the string trailer. + (NAME, token.LPAR): LPAR, + (NAME, DEFAULT_TOKEN): DONE, + # A '%' symbol can be followed by an '(' or a single argument (e.g. a + # string or variable name). + (PERCENT, token.LPAR): LPAR, + (PERCENT, DEFAULT_TOKEN): SINGLE_FMT_ARG, + # If a '%' symbol is followed by a single argument, that argument is + # the last leaf in the string trailer. + (SINGLE_FMT_ARG, DEFAULT_TOKEN): DONE, + # If present, a ')' symbol is the last symbol in a string trailer. + # (NOTE: LPARS and nested RPARS are not included in this lookup table, + # since they are treated as a special case by the parsing logic in this + # classes' implementation.) + (RPAR, DEFAULT_TOKEN): DONE, + } + + def __init__(self) -> None: + self._state = self.START + self._unmatched_lpars = 0 + + def parse(self, leaves: List[Leaf], string_idx: int) -> int: + """ + Pre-conditions: + * @leaves[@string_idx].type == token.STRING + + Returns: + The index directly after the last leaf which is apart of the string + trailer, if a "trailer" exists. + OR + @string_idx + 1, if no string "trailer" exists. + """ + assert leaves[string_idx].type == token.STRING + + idx = string_idx + 1 + while idx < len(leaves) and self._next_state(leaves[idx]): + idx += 1 + return idx + + def _next_state(self, leaf: Leaf) -> bool: + """ + Pre-conditions: + * On the first call to this function, @leaf MUST be the leaf that + was directly after the string leaf in question (e.g. if our target + string is `line.leaves[i]` then the first call to this method must + be `line.leaves[i + 1]`). + * On the next call to this function, the leaf paramater passed in + MUST be the leaf directly following @leaf. + + Returns: + True iff @leaf is apart of the string's trailer. + """ + # We ignore empty LPAR or RPAR leaves. + if is_empty_par(leaf): + return True + + next_token = leaf.type + if next_token == token.LPAR: + self._unmatched_lpars += 1 + + current_state = self._state + + # The LPAR parser state is a special case. We will return True until we + # find the matching RPAR token. + if current_state == self.LPAR: + if next_token == token.RPAR: + self._unmatched_lpars -= 1 + if self._unmatched_lpars == 0: + self._state = self.RPAR + # Otherwise, we use a lookup table to determine the next state. + else: + # If the lookup table matches the current state to the next + # token, we use the lookup table. + if (current_state, next_token) in self._goto: + self._state = self._goto[current_state, next_token] + else: + # Otherwise, we check if a the current state was assigned a + # default. + if (current_state, self.DEFAULT_TOKEN) in self._goto: + self._state = self._goto[current_state, self.DEFAULT_TOKEN] + # If no default has been assigned, then this parser has a logic + # error. + else: + raise RuntimeError(f"{self.__class__.__name__} LOGIC ERROR!") + + if self._state == self.DONE: + return False + + return True + + +def TErr(err_msg: str) -> Err[CannotTransform]: + """(T)ransform Err + + Convenience function used when working with the TResult type. + """ + cant_transform = CannotTransform(err_msg) + return Err(cant_transform) + + +def contains_pragma_comment(comment_list: List[Leaf]) -> bool: + """ + Returns: + True iff one of the comments in @comment_list is a pragma used by one + of the more common static analysis tools for python (e.g. mypy, flake8, + pylint). + """ + for comment in comment_list: + if comment.value.startswith(("# type:", "# noqa", "# pylint:")): + return True + + return False + + +def insert_str_child_factory(string_leaf: Leaf) -> Callable[[LN], None]: + """ + Factory for a convenience function that is used to orphan @string_leaf + and then insert multiple new leaves into the same part of the node + structure that @string_leaf had originally occupied. + + Examples: + Let `string_leaf = Leaf(token.STRING, '"foo"')` and `N = + string_leaf.parent`. Assume the node `N` has the following + original structure: + + Node( + expr_stmt, [ + Leaf(NAME, 'x'), + Leaf(EQUAL, '='), + Leaf(STRING, '"foo"'), + ] + ) + + We then run the code snippet shown below. + ``` + insert_str_child = insert_str_child_factory(string_leaf) + + lpar = Leaf(token.LPAR, '(') + insert_str_child(lpar) + + bar = Leaf(token.STRING, '"bar"') + insert_str_child(bar) + + rpar = Leaf(token.RPAR, ')') + insert_str_child(rpar) + ``` + + After which point, it follows that `string_leaf.parent is None` and + the node `N` now has the following structure: + + Node( + expr_stmt, [ + Leaf(NAME, 'x'), + Leaf(EQUAL, '='), + Leaf(LPAR, '('), + Leaf(STRING, '"bar"'), + Leaf(RPAR, ')'), + ] + ) + """ + string_parent = string_leaf.parent + string_child_idx = string_leaf.remove() + + def insert_str_child(child: LN) -> None: + nonlocal string_child_idx + + assert string_parent is not None + assert string_child_idx is not None + + string_parent.insert_child(string_child_idx, child) + string_child_idx += 1 + + return insert_str_child + + +def has_triple_quotes(string: str) -> bool: + """ + Returns: + True iff @string starts with three quotation characters. + """ + raw_string = string.lstrip(STRING_PREFIX_CHARS) + return raw_string[:3] in {'"""', "'''"} + + +def parent_type(node: Optional[LN]) -> Optional[NodeType]: + """ + Returns: + @node.parent.type, if @node is not None and has a parent. + OR + None, otherwise. + """ + if node is None or node.parent is None: + return None + + return node.parent.type + + +def is_empty_par(leaf: Leaf) -> bool: + return is_empty_lpar(leaf) or is_empty_rpar(leaf) + + +def is_empty_lpar(leaf: Leaf) -> bool: + return leaf.type == token.LPAR and leaf.value == "" + + +def is_empty_rpar(leaf: Leaf) -> bool: + return leaf.type == token.RPAR and leaf.value == "" + + +def is_valid_index_factory(seq: Sequence[Any]) -> Callable[[int], bool]: + """ + Examples: + ``` + my_list = [1, 2, 3] + + is_valid_index = is_valid_index_factory(my_list) + + assert is_valid_index(0) + assert is_valid_index(2) + + assert not is_valid_index(3) + assert not is_valid_index(-1) + ``` + """ + + def is_valid_index(idx: int) -> bool: + """ + Returns: + True iff @idx is positive AND seq[@idx] does NOT raise an + IndexError. + """ + return 0 <= idx < len(seq) + + return is_valid_index + + +def line_to_string(line: Line) -> str: + """Returns the string representation of @line. + + WARNING: This is known to be computationally expensive. + """ + return str(line).strip("\n") + + +def append_leaves(new_line: Line, old_line: Line, leaves: List[Leaf]) -> None: + """ + Append leaves (taken from @old_line) to @new_line, making sure to fix the + underlying Node structure where appropriate. + + All of the leaves in @leaves are duplicated. The duplicates are then + appended to @new_line and used to replace their originals in the underlying + Node structure. Any comments attatched to the old leaves are reattached to + the new leaves. + + Pre-conditions: + set(@leaves) is a subset of set(@old_line.leaves). + """ + for old_leaf in leaves: + assert old_leaf in old_line.leaves + + new_leaf = Leaf(old_leaf.type, old_leaf.value) + replace_child(old_leaf, new_leaf) + new_line.append(new_leaf) + + for comment_leaf in old_line.comments_after(old_leaf): + new_line.append(comment_leaf, preformatted=True) + + +def replace_child(old_child: LN, new_child: LN) -> None: + """ + Side Effects: + * If @old_child.parent is set, replace @old_child with @new_child in + @old_child's underlying Node structure. + OR + * Otherwise, this function does nothing. + """ + parent = old_child.parent + if not parent: + return + + child_idx = old_child.remove() + if child_idx is not None: + parent.insert_child(child_idx, new_child) + + +def get_string_prefix(string: str) -> str: + """ + Pre-conditions: + * assert_is_leaf_string(@string) + + Returns: + @string's prefix (e.g. '', 'r', 'f', or 'rf'). + """ + assert_is_leaf_string(string) + + prefix = "" + prefix_idx = 0 + while string[prefix_idx] in STRING_PREFIX_CHARS: + prefix += string[prefix_idx].lower() + prefix_idx += 1 + + return prefix + + +def assert_is_leaf_string(string: str) -> None: + """ + Checks the pre-condition that @string has the format that you would expect + of `leaf.value` where `leaf` is some Leaf such that `leaf.type == + token.STRING`. A more precise description of the pre-conditions that are + checked are listed below. + + Pre-conditions: + * @string starts with either ', ", ', or " where + `set()` is some subset of `set(STRING_PREFIX_CHARS)`. + * @string ends with a quote character (' or "). + + Raises: + AssertionError(...) if the pre-conditions listed above are not + satisfied. + """ + dquote_idx = string.find('"') + squote_idx = string.find("'") + if -1 in [dquote_idx, squote_idx]: + quote_idx = max(dquote_idx, squote_idx) + else: + quote_idx = min(squote_idx, dquote_idx) + + assert ( + 0 <= quote_idx < len(string) - 1 + ), f"{string!r} is missing a starting quote character (' or \")." + assert string[-1] in ( + "'", + '"', + ), f"{string!r} is missing an ending quote character (' or \")." + assert set(string[:quote_idx]).issubset( + set(STRING_PREFIX_CHARS) + ), f"{set(string[:quote_idx])} is NOT a subset of {set(STRING_PREFIX_CHARS)}." + + +def left_hand_split(line: Line, _features: Collection[Feature] = ()) -> Iterator[Line]: + """Split line into many lines, starting with the first matching bracket pair. + + Note: this usually looks weird, only use this for function definitions. + 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 + matching_bracket: Optional[Leaf] = None for leaf in line.leaves: if ( current_leaves is body_leaves @@ -2261,7 +4704,7 @@ def left_hand_split( def right_hand_split( line: Line, line_length: int, - supports_trailing_commas: bool = False, + features: Collection[Feature] = (), omit: Collection[LeafID] = (), ) -> Iterator[Line]: """Split line into many lines, starting with the last matching bracket pair. @@ -2276,8 +4719,8 @@ def right_hand_split( body_leaves: List[Leaf] = [] head_leaves: List[Leaf] = [] current_leaves = tail_leaves - opening_bracket = None - closing_bracket = None + opening_bracket: Optional[Leaf] = None + closing_bracket: Optional[Leaf] = None for leaf in reversed(line.leaves): if current_leaves is body_leaves: if leaf is opening_bracket: @@ -2320,12 +4763,7 @@ def right_hand_split( ): omit = {id(closing_bracket), *omit} try: - yield from right_hand_split( - line, - line_length, - supports_trailing_commas=supports_trailing_commas, - omit=omit, - ) + yield from right_hand_split(line, line_length, features=features, omit=omit) return except CannotSplit: @@ -2339,10 +4777,10 @@ def right_hand_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." + "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) @@ -2373,8 +4811,8 @@ def bracket_split_succeeded_or_raise(head: Line, body: Line, tail: Line) -> None elif tail_len < 3: raise CannotSplit( - f"Splitting brackets on an empty body to save " - f"{tail_len} characters is not worth it" + f"Splitting brackets on an empty body to save {tail_len} characters is" + " not worth it" ) @@ -2393,10 +4831,23 @@ def bracket_split_build_line( if leaves: # Since body is a new indent level, remove spurious leading whitespace. normalize_prefix(leaves[0], inside_brackets=True) - # Ensure a trailing comma when expected. - if original.is_import: - if leaves[-1].type != token.COMMA: - leaves.append(Leaf(token.COMMA, ",")) + # Ensure a trailing comma for imports and standalone function arguments, but + # be careful not to add one after any comments or within type annotations. + no_commas = ( + original.is_def + and opening_bracket.value == "(" + and not any(l.type == token.COMMA for l in leaves) + ) + + if original.is_import or no_commas: + for i in range(len(leaves) - 1, -1, -1): + if leaves[i].type == STANDALONE_COMMENT: + continue + + if leaves[i].type != token.COMMA: + leaves.insert(i + 1, Leaf(token.COMMA, ",")) + break + # Populate the line for leaf in leaves: result.append(leaf, preformatted=True) @@ -2407,17 +4858,15 @@ def bracket_split_build_line( return result -def dont_increase_indentation(split_func: SplitFunc) -> SplitFunc: +def dont_increase_indentation(split_func: Transformer) -> Transformer: """Normalize prefix of the first leaf in every line returned by `split_func`. This is a decorator over relevant split functions. """ @wraps(split_func) - def split_wrapper( - line: Line, supports_trailing_commas: bool = False - ) -> Iterator[Line]: - for l in split_func(line, supports_trailing_commas): + 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 @@ -2425,13 +4874,11 @@ def dont_increase_indentation(split_func: SplitFunc) -> SplitFunc: @dont_increase_indentation -def delimiter_split( - line: Line, supports_trailing_commas: bool = False -) -> Iterator[Line]: +def delimiter_split(line: Line, features: Collection[Feature] = ()) -> Iterator[Line]: """Split according to delimiters of the highest priority. - If `supports_trailing_commas` is True, the split will add trailing commas - also in function signatures that contain `*` and `**`. + 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] @@ -2470,10 +4917,16 @@ def delimiter_split( yield from append_to_line(comment_after) lowest_depth = min(lowest_depth, leaf.bracket_depth) - if leaf.bracket_depth == lowest_depth and is_vararg( - leaf, within=VARARGS_PARENTS - ): - trailing_comma_safe = trailing_comma_safe and supports_trailing_commas + 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 @@ -2492,7 +4945,7 @@ def delimiter_split( @dont_increase_indentation def standalone_comment_split( - line: Line, supports_trailing_commas: bool = False + line: Line, features: Collection[Feature] = () ) -> Iterator[Line]: """Split standalone comments from the rest of the line.""" if not line.contains_standalone_comments(0): @@ -2535,14 +4988,12 @@ def is_import(leaf: Leaf) -> bool: ) -def is_special_comment(leaf: Leaf) -> bool: +def is_type_comment(leaf: Leaf, suffix: str = "") -> bool: """Return True if the given leaf is a special comment. Only returns true for type comments for now.""" t = leaf.type v = leaf.value - return bool( - (t == token.COMMENT or t == STANDALONE_COMMENT) and (v.startswith("# type:")) - ) + return t in {token.COMMENT, STANDALONE_COMMENT} and v.startswith("# type:" + suffix) def normalize_prefix(leaf: Leaf, *, inside_brackets: bool) -> None: @@ -2570,10 +5021,10 @@ def normalize_string_prefix(leaf: Leaf, remove_u_prefix: bool = False) -> None: Note: Mutates its argument. """ - match = re.match(r"^([furbFURB]*)(.*)$", leaf.value, re.DOTALL) + match = re.match(r"^([" + STRING_PREFIX_CHARS + r"]*)(.*)$", leaf.value, re.DOTALL) assert match is not None, f"failed to match string {leaf.value!r}" orig_prefix = match.group(1) - new_prefix = orig_prefix.lower() + new_prefix = orig_prefix.replace("F", "f").replace("B", "b").replace("U", "u") if remove_u_prefix: new_prefix = new_prefix.replace("u", "") leaf.value = f"{new_prefix}{match.group(2)}" @@ -2587,7 +5038,7 @@ def normalize_string_quotes(leaf: Leaf) -> None: Note: Mutates its argument. """ - value = leaf.value.lstrip("furbFURB") + value = leaf.value.lstrip(STRING_PREFIX_CHARS) if value[:3] == '"""': return @@ -2627,11 +5078,20 @@ def normalize_string_quotes(leaf: Leaf) -> None: new_body = sub_twice(escaped_orig_quote, rf"\1\2{orig_quote}", new_body) new_body = sub_twice(unescaped_new_quote, rf"\1\\{new_quote}", new_body) if "f" in prefix.casefold(): - matches = re.findall(r"[^{]\{(.*?)\}[^}]", new_body) + matches = re.findall( + r""" + (?:[^{]|^)\{ # start of the string or a non-{ followed by a single { + ([^{].*?) # contents of the brackets except if begins with {{ + \}(?:[^}]|$) # 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] + '\\"' @@ -2694,7 +5154,7 @@ def format_float_or_int_string(text: str) -> str: 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 immeditely after which parens + `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 @@ -2704,22 +5164,30 @@ def normalize_invisible_parens(node: Node, parens_after: Set[str]) -> None: if pc.value in FMT_OFF: # This `node` has a prefix with `# fmt: off`, don't mess with parens. return - check_lpar = False for index, child in enumerate(list(node.children)): + # Fixes a bug where invisible parens are not properly stripped from + # assignment statements that contain type annotations. + if isinstance(child, Node) and child.type == syms.annassign: + normalize_invisible_parens(child, parens_after=parens_after) + + # Add parentheses around long tuple unpacking in assignments. + if ( + index == 0 + 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: - if maybe_make_parens_invisible_in_atom(child): - lpar = Leaf(token.LPAR, "") - rpar = Leaf(token.RPAR, "") - index = child.remove() or 0 - node.insert_child(index, Node(syms.atom, [lpar, child, rpar])) + if maybe_make_parens_invisible_in_atom(child, parent=node): + wrap_in_parentheses(node, child, visible=False) elif is_one_tuple(child): - # wrap child in visible parentheses - lpar = Leaf(token.LPAR, "(") - rpar = Leaf(token.RPAR, ")") - child.remove() - node.insert_child(index, Node(syms.atom, [lpar, child, rpar])) + wrap_in_parentheses(node, child, visible=True) elif node.type == syms.import_from: # "import from" nodes store parentheses directly as part of # the statement @@ -2734,11 +5202,7 @@ def normalize_invisible_parens(node: Node, parens_after: Set[str]) -> None: 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 - node.insert_child(index, Node(syms.atom, [lpar, child, rpar])) + wrap_in_parentheses(node, child, visible=False) check_lpar = isinstance(child, Leaf) and child.value in parens_after @@ -2782,7 +5246,7 @@ def convert_one_fmt_off_pair(node: Node) -> bool: # That happens when one of the `ignored_nodes` ended with a NEWLINE # leaf (possibly followed by a DEDENT). hidden_value = hidden_value[:-1] - first_idx = None + first_idx: Optional[int] = None for ignored in ignored_nodes: index = ignored.remove() if first_idx is None: @@ -2811,17 +5275,60 @@ def generate_ignored_nodes(leaf: Leaf) -> Iterator[LN]: """ container: Optional[LN] = container_of(leaf) while container is not None and container.type != token.ENDMARKER: - for comment in list_comments(container.prefix, is_endmarker=False): - if comment.value in FMT_ON: - return + if is_fmt_on(container): + return + + # fix for fmt: on in children + if contains_fmt_on_at_column(container, leaf.column): + for child in container.children: + if contains_fmt_on_at_column(child, leaf.column): + return + yield child + else: + yield container + container = container.next_sibling + + +def is_fmt_on(container: LN) -> bool: + """Determine whether formatting is switched on within a container. + Determined by whether the last `# fmt:` comment is `on` or `off`. + """ + fmt_on = False + for comment in list_comments(container.prefix, is_endmarker=False): + if comment.value in FMT_ON: + fmt_on = True + elif comment.value in FMT_OFF: + fmt_on = False + return fmt_on + + +def contains_fmt_on_at_column(container: LN, column: int) -> bool: + """Determine if children at a given column have formatting switched on.""" + for child in container.children: + if ( + isinstance(child, Node) + and first_leaf_column(child) == column + or isinstance(child, Leaf) + and child.column == column + ): + if is_fmt_on(child): + return True + + return False - yield container - container = container.next_sibling +def first_leaf_column(node: Node) -> Optional[int]: + """Returns the column of the first leaf child of a node.""" + for child in node.children: + if isinstance(child, Leaf): + return child.column + return None -def maybe_make_parens_invisible_in_atom(node: LN) -> bool: +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. @@ -2830,7 +5337,7 @@ def maybe_make_parens_invisible_in_atom(node: LN) -> bool: node.type != syms.atom or is_empty_tuple(node) or is_one_tuple(node) - or is_yield(node) + or (is_yield(node) and parent.type != syms.expr_stmt) or max_delimiter_priority_in_atom(node) >= COMMA_PRIORITY ): return False @@ -2838,16 +5345,40 @@ def maybe_make_parens_invisible_in_atom(node: LN) -> bool: first = node.children[0] last = node.children[-1] if first.type == token.LPAR and last.type == token.RPAR: + middle = node.children[1] # make parentheses invisible first.value = "" # type: ignore last.value = "" # type: ignore - if len(node.children) > 1: - maybe_make_parens_invisible_in_atom(node.children[1]) + 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 ( @@ -2858,18 +5389,43 @@ def is_empty_tuple(node: LN) -> bool: ) +def unwrap_singleton_parenthesis(node: LN) -> Optional[LN]: + """Returns `wrapped` if `node` is of the shape ( wrapped ). + + Parenthesis can be optional. Returns None otherwise""" + if len(node.children) != 3: + return None + + lpar, wrapped, rpar = node.children + if not (lpar.type == token.LPAR and rpar.type == token.RPAR): + return None + + return wrapped + + +def wrap_in_parentheses(parent: Node, child: LN, *, visible: bool = True) -> None: + """Wrap `child` in parentheses. + + This replaces `child` with an atom holding the parentheses and the old + child. That requires moving the prefix. + + If `visible` is False, the leaves will be valueless (and thus invisible). + """ + lpar = Leaf(token.LPAR, "(" if visible else "") + rpar = Leaf(token.RPAR, ")" if visible else "") + prefix = child.prefix + child.prefix = "" + index = child.remove() or 0 + new_child = Node(syms.atom, [lpar, child, rpar]) + new_child.prefix = prefix + parent.insert_child(index, new_child) + + def is_one_tuple(node: LN) -> bool: """Return True if `node` holds a tuple with one element, with or without parens.""" if node.type == syms.atom: - if len(node.children) != 3: - return False - - lpar, gexp, rpar = node.children - if not ( - lpar.type == token.LPAR - and gexp.type == syms.testlist_gexp - and rpar.type == token.RPAR - ): + gexp = unwrap_singleton_parenthesis(node) + if gexp is None or gexp.type != syms.testlist_gexp: return False return len(gexp.children) == 2 and gexp.children[1].type == token.COMMA @@ -2881,6 +5437,12 @@ def is_one_tuple(node: LN) -> bool: ) +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: @@ -2910,7 +5472,7 @@ def is_vararg(leaf: Leaf, within: Set[NodeType]) -> bool: extended iterable unpacking (PEP 3132) and additional unpacking generalizations (PEP 448). """ - if leaf.type not in STARS or not leaf.parent: + if leaf.type not in VARARGS_SPECIALS or not leaf.parent: return False p = leaf.parent @@ -2927,8 +5489,7 @@ def is_vararg(leaf: Leaf, within: Set[NodeType]) -> bool: def is_multiline_string(leaf: Leaf) -> bool: """Return True if `leaf` is a multiline string that actually spans many lines.""" - value = leaf.value.lstrip("furbFURB") - return value[:3] in {'"""', "'''"} and "\n" in value + return has_triple_quotes(leaf.value) and "\n" in leaf.value def is_stub_suite(node: Node) -> bool: @@ -2960,7 +5521,7 @@ def is_stub_body(node: LN) -> bool: ) -def max_delimiter_priority_in_atom(node: LN) -> int: +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. @@ -2992,7 +5553,7 @@ def ensure_visible(leaf: Leaf) -> None: """Make sure parentheses are visible. They could be invisible as part of some statements (see - :func:`normalize_invible_parens` and :func:`visit_import_from`). + :func:`normalize_invisible_parens` and :func:`visit_import_from`). """ if leaf.type == token.LPAR: leaf.value = "(" @@ -3025,8 +5586,9 @@ def get_features_used(node: Node) -> Set[Feature]: Currently looking for: - f-strings; - - underscores in numeric literals; and - - trailing commas after * or ** in function signatures and calls. + - underscores in numeric literals; + - trailing commas after * or ** in function signatures and calls; + - positional only arguments in function signatures and lambdas; """ features: Set[Feature] = set() for n in node.pre_order(): @@ -3039,19 +5601,31 @@ def get_features_used(node: Node) -> Set[Feature]: 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.TRAILING_COMMA) + features.add(feature) if ch.type == syms.argument: for argch in ch.children: if argch.type in STARS: - features.add(Feature.TRAILING_COMMA) + features.add(feature) return features @@ -3078,8 +5652,8 @@ def generate_trailers_to_omit(line: Line, line_length: int) -> Iterator[Set[Leaf yield omit length = 4 * line.depth - opening_bracket = None - closing_bracket = None + opening_bracket: Optional[Leaf] = None + closing_bracket: Optional[Leaf] = None inner_brackets: Set[LeafID] = set() for index, leaf, leaf_length in enumerate_with_length(line, reversed=True): length += leaf_length @@ -3123,19 +5697,23 @@ def get_future_imports(node: Node) -> Set[str]: 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: - assert False, "Invalid syntax parsing imports" + 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. @@ -3145,24 +5723,39 @@ def get_future_imports(node: Node) -> Set[str]: and child.children[1].type == token.NEWLINE ): continue - else: - break + + break + elif first_child.type == syms.import_from: module_name = first_child.children[1] if not isinstance(module_name, Leaf) or module_name.value != "__future__": break + imports |= set(get_imports_from_children(first_child.children[3:])) else: break + return imports -def gen_python_files_in_dir( - path: Path, +@lru_cache() +def get_gitignore(root: Path) -> PathSpec: + """ Return a PathSpec matching gitignore content if present.""" + gitignore = root / ".gitignore" + lines: List[str] = [] + if gitignore.is_file(): + with gitignore.open() as gf: + lines = gf.readlines() + return PathSpec.from_lines("gitwildmatch", lines) + + +def gen_python_files( + paths: Iterable[Path], root: Path, - include: Pattern[str], - exclude: Pattern[str], + include: Optional[Pattern[str]], + exclude_regexes: Iterable[Pattern[str]], report: "Report", + gitignore: PathSpec, ) -> Iterator[Path]: """Generate all files under `path` whose paths are not excluded by the `exclude` regex, but are included by the `include` regex. @@ -3172,9 +5765,13 @@ def gen_python_files_in_dir( `report` is where output about exclusions goes. """ assert root.is_absolute(), f"INTERNAL ERROR: `root` must be absolute but is {root}" - for child in path.iterdir(): + for child in paths: + # Then ignore with `exclude` option. try: - normalized_path = "/" + child.resolve().relative_to(root).as_posix() + normalized_path = child.resolve().relative_to(root).as_posix() + except OSError as e: + report.path_ignored(child, f"cannot be read because {e}") + continue except ValueError: if child.is_symlink(): report.path_ignored( @@ -3184,18 +5781,32 @@ def gen_python_files_in_dir( raise + # First ignore files matching .gitignore + if gitignore.match_file(normalized_path): + report.path_ignored(child, "matches the .gitignore file content") + continue + + normalized_path = "/" + normalized_path if child.is_dir(): normalized_path += "/" - exclude_match = exclude.search(normalized_path) - if exclude_match and exclude_match.group(0): - report.path_ignored(child, f"matches the --exclude regular expression") + + is_excluded = False + for exclude in exclude_regexes: + exclude_match = exclude.search(normalized_path) if exclude else None + if exclude_match and exclude_match.group(0): + report.path_ignored(child, "matches the --exclude regular expression") + is_excluded = True + break + if is_excluded: continue if child.is_dir(): - yield from gen_python_files_in_dir(child, root, include, exclude, report) + yield from gen_python_files( + child.iterdir(), root, include, exclude_regexes, report, gitignore + ) elif child.is_file(): - include_match = include.search(normalized_path) + include_match = include.search(normalized_path) if include else True if include_match: yield child @@ -3218,7 +5829,7 @@ def find_project_root(srcs: Iterable[str]) -> Path: # Append a fake file so `parents` below returns `common_base_dir`, too. common_base /= "fake-file" for directory in common_base.parents: - if (directory / ".git").is_dir(): + if (directory / ".git").exists(): return directory if (directory / ".hg").is_dir(): @@ -3235,6 +5846,7 @@ class Report: """Provides a reformatting counter. Can be rendered with `str(report)`.""" check: bool = False + diff: bool = False quiet: bool = False verbose: bool = False change_count: int = 0 @@ -3244,7 +5856,7 @@ class Report: def done(self, src: Path, changed: Changed) -> None: """Increment the counter for successful reformatting. Write out a message.""" if changed is Changed.YES: - reformatted = "would reformat" if self.check else "reformatted" + reformatted = "would reformat" if self.check or self.diff else "reformatted" if self.verbose or not self.quiet: out(f"{reformatted} {src}") self.change_count += 1 @@ -3290,7 +5902,7 @@ class Report: Use `click.unstyle` to remove colors. """ - if self.check: + if self.check or self.diff: reformatted = "would be reformatted" unchanged = "would be left unchanged" failed = "would fail to reformat" @@ -3315,79 +5927,131 @@ class Report: return ", ".join(report) + "." -def assert_equivalent(src: str, dst: str) -> None: - """Raise AssertionError if `src` and `dst` aren't equivalent.""" +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 - import ast - import traceback + return ast27.parse(src) - def _v(node: ast.AST, depth: int = 0) -> Iterator[str]: - """Simple visitor generating strings to compare ASTs by content.""" - yield f"{' ' * depth}{node.__class__.__name__}(" - for field in sorted(node._fields): - try: - value = getattr(node, field) - except AttributeError: - continue +def _fixup_ast_constants( + node: Union[ast.AST, ast3.AST, ast27.AST] +) -> Union[ast.AST, ast3.AST, ast27.AST]: + """Map ast nodes deprecated in 3.8 to Constant.""" + if isinstance(node, (ast.Str, ast3.Str, ast27.Str, ast.Bytes, ast3.Bytes)): + return ast.Constant(value=node.s) - yield f"{' ' * (depth+1)}{field}=" + if isinstance(node, (ast.Num, ast3.Num, ast27.Num)): + return ast.Constant(value=node.n) - 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) - and isinstance(item, ast.Tuple) - ): - for item in item.elts: - yield from _v(item, depth + 2) - elif isinstance(item, ast.AST): - yield from _v(item, depth + 2) + if isinstance(node, (ast.NameConstant, ast3.NameConstant)): + return ast.Constant(value=node.value) + + return node + + +def _stringify_ast( + node: Union[ast.AST, ast3.AST, ast27.AST], depth: int = 0 +) -> Iterator[str]: + """Simple visitor generating strings to compare ASTs by content.""" + + node = _fixup_ast_constants(node) + + yield f"{' ' * depth}{node.__class__.__name__}(" + + for field in sorted(node._fields): # noqa: F402 + # TypeIgnore has only one field 'lineno' which breaks this comparison + type_ignore_classes = (ast3.TypeIgnore, ast27.TypeIgnore) + if sys.version_info >= (3, 8): + type_ignore_classes += (ast.TypeIgnore,) + if isinstance(node, type_ignore_classes): + break + + try: + value = getattr(node, field) + except AttributeError: + continue + + yield f"{' ' * (depth+1)}{field}=" + + if isinstance(value, list): + for item in value: + # Ignore nested tuples within del statements, because we may insert + # parentheses and they change the AST. + if ( + field == "targets" + and isinstance(node, (ast.Delete, ast3.Delete, ast27.Delete)) + and isinstance(item, (ast.Tuple, ast3.Tuple, ast27.Tuple)) + ): + for item in item.elts: + yield from _stringify_ast(item, depth + 2) - elif isinstance(value, ast.AST): - yield from _v(value, depth + 2) + elif isinstance(item, (ast.AST, ast3.AST, ast27.AST)): + yield from _stringify_ast(item, depth + 2) + elif isinstance(value, (ast.AST, ast3.AST, ast27.AST)): + yield from _stringify_ast(value, depth + 2) + + else: + # Constant strings may be indented across newlines, if they are + # docstrings; fold spaces after newlines when comparing + if ( + isinstance(node, ast.Constant) + and field == "value" + and isinstance(value, str) + ): + normalized = re.sub(r"\n[ \t]+", "\n ", value) else: - yield f"{' ' * (depth+2)}{value!r}, # {value.__class__.__name__}" + normalized = value + yield f"{' ' * (depth+2)}{normalized!r}, # {value.__class__.__name__}" - yield f"{' ' * depth}) # /{node.__class__.__name__}" + yield f"{' ' * depth}) # /{node.__class__.__name__}" + +def assert_equivalent(src: str, dst: str) -> None: + """Raise AssertionError if `src` and `dst` aren't equivalent.""" try: - src_ast = ast.parse(src) + src_ast = parse_ast(src) except Exception as exc: - major, minor = sys.version_info[:2] raise AssertionError( - f"cannot use --safe with this file; failed to parse source file " - f"with Python {major}.{minor}'s builtin AST. Re-run with --fast " - f"or stop using deprecated Python 2 syntax. AST error message: {exc}" + "cannot use --safe with this file; failed to parse source file. AST" + f" error message: {exc}" ) try: - dst_ast = ast.parse(dst) + 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/ambv/black/issues. " - f"This invalid output might be helpful: {log}" + f"INTERNAL ERROR: Black produced invalid code: {exc}. Please report a bug" + " on https://github.com/psf/black/issues. This invalid output might be" + f" helpful: {log}" ) from None - src_ast_str = "\n".join(_v(src_ast)) - dst_ast_str = "\n".join(_v(dst_ast)) + src_ast_str = "\n".join(_stringify_ast(src_ast)) + dst_ast_str = "\n".join(_stringify_ast(dst_ast)) if src_ast_str != dst_ast_str: log = dump_to_file(diff(src_ast_str, dst_ast_str, "src", "dst")) raise AssertionError( - f"INTERNAL ERROR: Black produced code that is not equivalent to " - f"the source. " - f"Please report a bug on https://github.com/ambv/black/issues. " - f"This diff might be helpful: {log}" + "INTERNAL ERROR: Black produced code that is not equivalent to the" + " source. Please report a bug on https://github.com/psf/black/issues. " + f" This diff might be helpful: {log}" ) from None -def assert_stable(src: str, dst: str, mode: FileMode) -> None: +def assert_stable(src: str, dst: str, mode: Mode) -> None: """Raise AssertionError if `dst` reformats differently the second time.""" newdst = format_str(dst, mode=mode) if dst != newdst: @@ -3396,17 +6060,15 @@ def assert_stable(src: str, dst: str, mode: FileMode) -> None: diff(dst, newdst, "first pass", "second pass"), ) raise AssertionError( - f"INTERNAL ERROR: Black produced different code on the second pass " - f"of the formatter. " - f"Please report a bug on https://github.com/ambv/black/issues. " - f"This diff might be helpful: {log}" + "INTERNAL ERROR: Black produced different code on the second pass of the" + " formatter. Please report a bug on https://github.com/psf/black/issues." + f" This diff might be helpful: {log}" ) from None +@mypyc_attr(patchable=True) def dump_to_file(*output: str) -> str: """Dump `output` to a temporary file. Return path to the file.""" - import tempfile - with tempfile.NamedTemporaryFile( mode="w", prefix="blk_", suffix=".log", delete=False, encoding="utf8" ) as f: @@ -3417,29 +6079,42 @@ def dump_to_file(*output: str) -> str: return f.name +@contextmanager +def nullcontext() -> Iterator[None]: + """Return an empty context manager. + + To be used like `nullcontext` in Python 3.7. + """ + yield + + def diff(a: str, b: str, a_name: str, b_name: str) -> str: """Return a unified diff string between strings `a` and `b`.""" import difflib - a_lines = [line + "\n" for line in a.split("\n")] - b_lines = [line + "\n" for line in b.split("\n")] + a_lines = [line + "\n" for line in a.splitlines()] + b_lines = [line + "\n" for line in b.splitlines()] return "".join( difflib.unified_diff(a_lines, b_lines, fromfile=a_name, tofile=b_name, n=5) ) -def cancel(tasks: Iterable[asyncio.Task]) -> None: +def cancel(tasks: Iterable["asyncio.Task[Any]"]) -> None: """asyncio signal handler that cancels all `tasks` and reports to stderr.""" err("Aborted!") for task in tasks: task.cancel() -def shutdown(loop: BaseEventLoop) -> None: +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 asyncio.Task.all_tasks(loop) if not task.done()] + to_cancel = [task for task in all_tasks(loop) if not task.done()] if not to_cancel: return @@ -3473,7 +6148,8 @@ def re_compile_maybe_verbose(regex: str) -> Pattern[str]: """ if "\n" in regex: regex = "(?x)" + regex - return re.compile(regex) + compiled: Pattern[str] = re.compile(regex) + return compiled def enumerate_reversed(sequence: Sequence[T]) -> Iterator[Tuple[Index, T]]: @@ -3500,7 +6176,6 @@ def enumerate_with_length( if "\n" in leaf.value: return # Multiline strings, we can't continue. - comment: Optional[Leaf] for comment in line.comments_after(leaf): length += len(comment.value) @@ -3513,7 +6188,7 @@ def is_line_short_enough(line: Line, *, line_length: int, line_str: str = "") -> Uses the provided `line_str` rendering, if any, otherwise computes a new one. """ if not line_str: - line_str = str(line).strip("\n") + line_str = line_to_string(line) return ( len(line_str) <= line_length and "\n" not in line_str # multiline strings @@ -3646,11 +6321,11 @@ def can_omit_invisible_parens(line: Line, line_length: int) -> bool: return False -def get_cache_file(mode: FileMode) -> Path: +def get_cache_file(mode: Mode) -> Path: return CACHE_DIR / f"cache.{mode.get_cache_key()}.pickle" -def read_cache(mode: FileMode) -> Cache: +def read_cache(mode: Mode) -> Cache: """Read the cache if it exists and is well formed. If it is not well formed, the call to write_cache later should resolve the issue. @@ -3662,7 +6337,7 @@ def read_cache(mode: FileMode) -> Cache: with cache_file.open("rb") as fobj: try: cache: Cache = pickle.load(fobj) - except pickle.UnpicklingError: + except (pickle.UnpicklingError, ValueError): return {} return cache @@ -3690,14 +6365,14 @@ def filter_cached(cache: Cache, sources: Iterable[Path]) -> Tuple[Set[Path], Set return todo, done -def write_cache(cache: Cache, sources: Iterable[Path], mode: FileMode) -> None: +def write_cache(cache: Cache, sources: Iterable[Path], mode: Mode) -> None: """Update the cache file.""" cache_file = get_cache_file(mode) try: CACHE_DIR.mkdir(parents=True, exist_ok=True) new_cache = {**cache, **{src.resolve(): get_cache_info(src) for src in sources}} with tempfile.NamedTemporaryFile(dir=str(cache_file.parent), delete=False) as f: - pickle.dump(new_cache, f, protocol=pickle.HIGHEST_PROTOCOL) + pickle.dump(new_cache, f, protocol=4) os.replace(f.name, cache_file) except OSError: pass @@ -3731,5 +6406,32 @@ def patched_main() -> None: main() +def fix_docstring(docstring: str, prefix: str) -> str: + # https://www.python.org/dev/peps/pep-0257/#handling-docstring-indentation + if not docstring: + return "" + # Convert tabs to spaces (following the normal Python rules) + # and split into a list of lines: + lines = docstring.expandtabs().splitlines() + # Determine minimum indentation (first line doesn't count): + indent = sys.maxsize + for line in lines[1:]: + stripped = line.lstrip() + if stripped: + indent = min(indent, len(line) - len(stripped)) + # Remove indentation (first line is special): + trimmed = [lines[0].strip()] + if indent < sys.maxsize: + last_line_idx = len(lines) - 2 + for i, line in enumerate(lines[1:]): + stripped_line = line[indent:].rstrip() + if stripped_line or i == last_line_idx: + trimmed.append(prefix + stripped_line) + else: + trimmed.append("") + # Return a single string: + return "\n".join(trimmed) + + if __name__ == "__main__": patched_main()