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Fix long trivial assignments being wrapped in unnecessary parentheses
[etc/vim.git] / black.py
index 488f5811f04230f682638e32f3483ab030a81c23..35af598e59032c62397bff766d06b006df41174c 100644 (file)
--- a/black.py
+++ b/black.py
@@ -1,18 +1,20 @@
 import asyncio
-import pickle
 from asyncio.base_events import BaseEventLoop
 from concurrent.futures import Executor, ProcessPoolExecutor
+from datetime import datetime
 from enum import Enum, Flag
 from functools import partial, wraps
+import io
 import keyword
 import logging
 from multiprocessing import Manager
 import os
 from pathlib import Path
+import pickle
 import re
-import tokenize
 import signal
 import sys
+import tokenize
 from typing import (
     Any,
     Callable,
@@ -46,12 +48,17 @@ from blib2to3.pgen2.parse import ParseError
 
 __version__ = "18.5b1"
 DEFAULT_LINE_LENGTH = 88
+DEFAULT_EXCLUDES = (
+    r"/(\.git|\.hg|\.mypy_cache|\.tox|\.venv|_build|buck-out|build|dist)/"
+)
+DEFAULT_INCLUDES = r"\.pyi?$"
 CACHE_DIR = Path(user_cache_dir("black", version=__version__))
 
 
 # types
 FileContent = str
 Encoding = str
+NewLine = str
 Depth = int
 NodeType = int
 LeafID = int
@@ -115,6 +122,13 @@ class WriteBack(Enum):
     YES = 1
     DIFF = 2
 
+    @classmethod
+    def from_configuration(cls, *, check: bool, diff: bool) -> "WriteBack":
+        if check and not diff:
+            return cls.NO
+
+        return cls.DIFF if diff else cls.YES
+
 
 class Changed(Enum):
     NO = 0
@@ -126,6 +140,20 @@ class FileMode(Flag):
     AUTO_DETECT = 0
     PYTHON36 = 1
     PYI = 2
+    NO_STRING_NORMALIZATION = 4
+
+    @classmethod
+    def from_configuration(
+        cls, *, py36: bool, pyi: bool, skip_string_normalization: bool
+    ) -> "FileMode":
+        mode = cls.AUTO_DETECT
+        if py36:
+            mode |= cls.PYTHON36
+        if pyi:
+            mode |= cls.PYI
+        if skip_string_normalization:
+            mode |= cls.NO_STRING_NORMALIZATION
+        return mode
 
 
 @click.command()
@@ -137,6 +165,29 @@ class FileMode(Flag):
     help="How many character per line to allow.",
     show_default=True,
 )
+@click.option(
+    "--py36",
+    is_flag=True,
+    help=(
+        "Allow using Python 3.6-only syntax on all input files.  This will put "
+        "trailing commas in function signatures and calls also after *args and "
+        "**kwargs.  [default: per-file auto-detection]"
+    ),
+)
+@click.option(
+    "--pyi",
+    is_flag=True,
+    help=(
+        "Format all input files like typing stubs regardless of file extension "
+        "(useful when piping source on standard input)."
+    ),
+)
+@click.option(
+    "-S",
+    "--skip-string-normalization",
+    is_flag=True,
+    help="Don't normalize string quotes or prefixes.",
+)
 @click.option(
     "--check",
     is_flag=True,
@@ -157,29 +208,46 @@ class FileMode(Flag):
     help="If --fast given, skip temporary sanity checks. [default: --safe]",
 )
 @click.option(
-    "-q",
-    "--quiet",
-    is_flag=True,
+    "--include",
+    type=str,
+    default=DEFAULT_INCLUDES,
     help=(
-        "Don't emit non-error messages to stderr. Errors are still emitted, "
-        "silence those with 2>/dev/null."
+        "A regular expression that matches files and directories that should be "
+        "included on recursive searches.  An empty value means all files are "
+        "included regardless of the name.  Use forward slashes for directories on "
+        "all platforms (Windows, too).  Exclusions are calculated first, inclusions "
+        "later."
     ),
+    show_default=True,
 )
 @click.option(
-    "--pyi",
+    "--exclude",
+    type=str,
+    default=DEFAULT_EXCLUDES,
+    help=(
+        "A regular expression that matches files and directories that should be "
+        "excluded on recursive searches.  An empty value means no paths are excluded. "
+        "Use forward slashes for directories on all platforms (Windows, too).  "
+        "Exclusions are calculated first, inclusions later."
+    ),
+    show_default=True,
+)
+@click.option(
+    "-q",
+    "--quiet",
     is_flag=True,
     help=(
-        "Consider all input files typing stubs regardless of file extension "
-        "(useful when piping source on standard input)."
+        "Don't emit non-error messages to stderr. Errors are still emitted, "
+        "silence those with 2>/dev/null."
     ),
 )
 @click.option(
-    "--py36",
+    "-v",
+    "--verbose",
     is_flag=True,
     help=(
-        "Allow using Python 3.6-only syntax on all input files.  This will put "
-        "trailing commas in function signatures and calls also after *args and "
-        "**kwargs.  [default: per-file auto-detection]"
+        "Also emit messages to stderr about files that were not changed or were "
+        "ignored due to --exclude=."
     ),
 )
 @click.version_option(version=__version__)
@@ -199,43 +267,51 @@ def main(
     fast: bool,
     pyi: bool,
     py36: bool,
+    skip_string_normalization: bool,
     quiet: bool,
+    verbose: bool,
+    include: str,
+    exclude: str,
     src: List[str],
 ) -> None:
     """The uncompromising code formatter."""
-    sources: List[Path] = []
+    write_back = WriteBack.from_configuration(check=check, diff=diff)
+    mode = FileMode.from_configuration(
+        py36=py36, pyi=pyi, skip_string_normalization=skip_string_normalization
+    )
+    report = Report(check=check, quiet=quiet, verbose=verbose)
+    sources: Set[Path] = set()
+    try:
+        include_regex = re.compile(include)
+    except re.error:
+        err(f"Invalid regular expression for include given: {include!r}")
+        ctx.exit(2)
+    try:
+        exclude_regex = re.compile(exclude)
+    except re.error:
+        err(f"Invalid regular expression for exclude given: {exclude!r}")
+        ctx.exit(2)
+    root = find_project_root(src)
     for s in src:
         p = Path(s)
         if p.is_dir():
-            sources.extend(gen_python_files_in_dir(p))
-        elif p.is_file():
+            sources.update(
+                gen_python_files_in_dir(p, root, include_regex, exclude_regex, report)
+            )
+        elif p.is_file() or s == "-":
             # if a file was explicitly given, we don't care about its extension
-            sources.append(p)
-        elif s == "-":
-            sources.append(Path("-"))
+            sources.add(p)
         else:
             err(f"invalid path: {s}")
-
-    if check and not diff:
-        write_back = WriteBack.NO
-    elif diff:
-        write_back = WriteBack.DIFF
-    else:
-        write_back = WriteBack.YES
-    mode = FileMode.AUTO_DETECT
-    if py36:
-        mode |= FileMode.PYTHON36
-    if pyi:
-        mode |= FileMode.PYI
-    report = Report(check=check, quiet=quiet)
     if len(sources) == 0:
-        out("No paths given. Nothing to do 😴")
+        if verbose or not quiet:
+            out("No paths given. Nothing to do 😴")
         ctx.exit(0)
         return
 
     elif len(sources) == 1:
         reformat_one(
-            src=sources[0],
+            src=sources.pop(),
             line_length=line_length,
             fast=fast,
             write_back=write_back,
@@ -260,9 +336,9 @@ def main(
             )
         finally:
             shutdown(loop)
-        if not quiet:
-            out("All done! ✨ 🍰 ✨")
-            click.echo(str(report))
+    if verbose or not quiet:
+        out("All done! ✨ 🍰 ✨")
+        click.echo(str(report))
     ctx.exit(report.return_code)
 
 
@@ -291,8 +367,8 @@ def reformat_one(
             cache: Cache = {}
             if write_back != WriteBack.DIFF:
                 cache = read_cache(line_length, mode)
-                src = src.resolve()
-                if src in cache and cache[src] == get_cache_info(src):
+                res_src = src.resolve()
+                if res_src in cache and cache[res_src] == get_cache_info(res_src):
                     changed = Changed.CACHED
             if changed is not Changed.CACHED and format_file_in_place(
                 src,
@@ -310,7 +386,7 @@ def reformat_one(
 
 
 async def schedule_formatting(
-    sources: List[Path],
+    sources: Set[Path],
     line_length: int,
     fast: bool,
     write_back: WriteBack,
@@ -330,7 +406,7 @@ async def schedule_formatting(
     if write_back != WriteBack.DIFF:
         cache = read_cache(line_length, mode)
         sources, cached = filter_cached(cache, sources)
-        for src in cached:
+        for src in sorted(cached):
             report.done(src, Changed.CACHED)
     cancelled = []
     formatted = []
@@ -393,8 +469,10 @@ def format_file_in_place(
     """
     if src.suffix == ".pyi":
         mode |= FileMode.PYI
-    with tokenize.open(src) as src_buffer:
-        src_contents = src_buffer.read()
+
+    then = datetime.utcfromtimestamp(src.stat().st_mtime)
+    with open(src, "rb") as buf:
+        src_contents, encoding, newline = decode_bytes(buf.read())
     try:
         dst_contents = format_file_contents(
             src_contents, line_length=line_length, fast=fast, mode=mode
@@ -403,16 +481,24 @@ def format_file_in_place(
         return False
 
     if write_back == write_back.YES:
-        with open(src, "w", encoding=src_buffer.encoding) as f:
+        with open(src, "w", encoding=encoding, newline=newline) as f:
             f.write(dst_contents)
     elif write_back == write_back.DIFF:
-        src_name = f"{src}  (original)"
-        dst_name = f"{src}  (formatted)"
+        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:
-            sys.stdout.write(diff_contents)
+            f = io.TextIOWrapper(
+                sys.stdout.buffer,
+                encoding=encoding,
+                newline=newline,
+                write_through=True,
+            )
+            f.write(diff_contents)
+            f.detach()
         finally:
             if lock:
                 lock.release()
@@ -431,7 +517,8 @@ def format_stdin_to_stdout(
     `line_length`, `fast`, `is_pyi`, and `force_py36` arguments are passed to
     :func:`format_file_contents`.
     """
-    src = sys.stdin.read()
+    then = datetime.utcnow()
+    src, encoding, newline = decode_bytes(sys.stdin.buffer.read())
     dst = src
     try:
         dst = format_file_contents(src, line_length=line_length, fast=fast, mode=mode)
@@ -441,12 +528,17 @@ def format_stdin_to_stdout(
         return False
 
     finally:
+        f = io.TextIOWrapper(
+            sys.stdout.buffer, encoding=encoding, newline=newline, write_through=True
+        )
         if write_back == WriteBack.YES:
-            sys.stdout.write(dst)
+            f.write(dst)
         elif write_back == WriteBack.DIFF:
-            src_name = "<stdin>  (original)"
-            dst_name = "<stdin>  (formatted)"
-            sys.stdout.write(diff(src, dst, src_name, dst_name))
+            now = datetime.utcnow()
+            src_name = f"STDIN\t{then} +0000"
+            dst_name = f"STDOUT\t{now} +0000"
+            f.write(diff(src, dst, src_name, dst_name))
+        f.detach()
 
 
 def format_file_contents(
@@ -487,8 +579,11 @@ def format_str(
     future_imports = get_future_imports(src_node)
     is_pyi = bool(mode & FileMode.PYI)
     py36 = bool(mode & FileMode.PYTHON36) or is_python36(src_node)
+    normalize_strings = not bool(mode & FileMode.NO_STRING_NORMALIZATION)
     lines = LineGenerator(
-        remove_u_prefix=py36 or "unicode_literals" in future_imports, is_pyi=is_pyi
+        remove_u_prefix=py36 or "unicode_literals" in future_imports,
+        is_pyi=is_pyi,
+        normalize_strings=normalize_strings,
     )
     elt = EmptyLineTracker(is_pyi=is_pyi)
     empty_line = Line()
@@ -504,6 +599,23 @@ def format_str(
     return dst_contents
 
 
+def decode_bytes(src: bytes) -> Tuple[FileContent, Encoding, NewLine]:
+    """Return a tuple of (decoded_contents, encoding, newline).
+
+    `newline` is either CRLF or LF but `decoded_contents` is decoded with
+    universal newlines (i.e. only contains LF).
+    """
+    srcbuf = io.BytesIO(src)
+    encoding, lines = tokenize.detect_encoding(srcbuf.readline)
+    if not lines:
+        return "", encoding, "\n"
+
+    newline = "\r\n" if b"\r\n" == lines[0][-2:] else "\n"
+    srcbuf.seek(0)
+    with io.TextIOWrapper(srcbuf, encoding) as tiow:
+        return tiow.read(), encoding, newline
+
+
 GRAMMARS = [
     pygram.python_grammar_no_print_statement_no_exec_statement,
     pygram.python_grammar_no_print_statement,
@@ -514,9 +626,8 @@ GRAMMARS = [
 def lib2to3_parse(src_txt: str) -> Node:
     """Given a string with source, return the lib2to3 Node."""
     grammar = pygram.python_grammar_no_print_statement
-    if src_txt[-1] != "\n":
-        nl = "\r\n" if "\r\n" in src_txt[:1024] else "\n"
-        src_txt += nl
+    if src_txt[-1:] != "\n":
+        src_txt += "\n"
     for grammar in GRAMMARS:
         drv = driver.Driver(grammar, pytree.convert)
         try:
@@ -660,6 +771,7 @@ UNPACKING_PARENTS = {
     syms.dictsetmaker,
     syms.listmaker,
     syms.testlist_gexp,
+    syms.testlist_star_expr,
 }
 TEST_DESCENDANTS = {
     syms.test,
@@ -1286,6 +1398,7 @@ class LineGenerator(Visitor[Line]):
     """
 
     is_pyi: bool = False
+    normalize_strings: bool = True
     current_line: Line = Factory(Line)
     remove_u_prefix: bool = False
 
@@ -1354,7 +1467,7 @@ class LineGenerator(Visitor[Line]):
 
             else:
                 normalize_prefix(node, inside_brackets=any_open_brackets)
-                if node.type == token.STRING:
+                if self.normalize_strings and node.type == token.STRING:
                     normalize_string_prefix(node, remove_u_prefix=self.remove_u_prefix)
                     normalize_string_quotes(node)
                 if node.type not in WHITESPACE:
@@ -2100,11 +2213,14 @@ def right_hand_split(
             result.append(leaf, preformatted=True)
             for comment_after in line.comments_after(leaf):
                 result.append(comment_after, preformatted=True)
-    bracket_split_succeeded_or_raise(head, body, tail)
     assert opening_bracket and closing_bracket
+    body.should_explode = should_explode(body, opening_bracket)
+    bracket_split_succeeded_or_raise(head, body, tail)
     if (
+        # the body shouldn't be exploded
+        not body.should_explode
         # the opening bracket is an optional paren
-        opening_bracket.type == token.LPAR
+        and opening_bracket.type == token.LPAR
         and not opening_bracket.value
         # the closing bracket is an optional paren
         and closing_bracket.type == token.RPAR
@@ -2121,11 +2237,15 @@ def right_hand_split(
                 yield from right_hand_split(line, line_length, py36=py36, omit=omit)
                 return
             except CannotSplit:
-                pass
+                if len(body.leaves) == 1 and not is_line_short_enough(
+                    body, line_length=line_length
+                ):
+                    raise CannotSplit(
+                        "Splitting failed, body is still too long and can't be split."
+                    )
 
     ensure_visible(opening_bracket)
     ensure_visible(closing_bracket)
-    body.should_explode = should_explode(body, opening_bracket)
     for result in (head, body, tail):
         if result:
             yield result
@@ -2736,33 +2856,64 @@ def get_future_imports(node: Node) -> Set[str]:
     return imports
 
 
-PYTHON_EXTENSIONS = {".py", ".pyi"}
-BLACKLISTED_DIRECTORIES = {
-    "build",
-    "buck-out",
-    "dist",
-    "_build",
-    ".git",
-    ".hg",
-    ".mypy_cache",
-    ".tox",
-    ".venv",
-}
-
+def gen_python_files_in_dir(
+    path: Path,
+    root: Path,
+    include: Pattern[str],
+    exclude: Pattern[str],
+    report: "Report",
+) -> Iterator[Path]:
+    """Generate all files under `path` whose paths are not excluded by the
+    `exclude` regex, but are included by the `include` regex.
 
-def gen_python_files_in_dir(path: Path) -> Iterator[Path]:
-    """Generate all files under `path` which aren't under BLACKLISTED_DIRECTORIES
-    and have one of the PYTHON_EXTENSIONS.
+    `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():
+        normalized_path = "/" + child.resolve().relative_to(root).as_posix()
         if child.is_dir():
-            if child.name in BLACKLISTED_DIRECTORIES:
-                continue
+            normalized_path += "/"
+        exclude_match = exclude.search(normalized_path)
+        if exclude_match and exclude_match.group(0):
+            report.path_ignored(child, f"matches --exclude={exclude.pattern}")
+            continue
 
-            yield from gen_python_files_in_dir(child)
+        if child.is_dir():
+            yield from gen_python_files_in_dir(child, root, include, exclude, report)
 
-        elif child.is_file() and child.suffix in PYTHON_EXTENSIONS:
-            yield child
+        elif child.is_file():
+            include_match = include.search(normalized_path)
+            if include_match:
+                yield child
+
+
+def find_project_root(srcs: List[str]) -> Path:
+    """Return a directory containing .git, .hg, or pyproject.toml.
+
+    That directory can be one of the directories passed in `srcs` or their
+    common parent.
+
+    If no directory in the tree contains a marker that would specify it's the
+    project root, the root of the file system is returned.
+    """
+    if not srcs:
+        return Path("/").resolve()
+
+    common_base = min(Path(src).resolve() for src in srcs)
+    if common_base.is_dir():
+        # Append a fake file so `parents` below returns `common_base_dir`, too.
+        common_base /= "fake-file"
+    for directory in common_base.parents:
+        if (directory / ".git").is_dir():
+            return directory
+
+        if (directory / ".hg").is_dir():
+            return directory
+
+        if (directory / "pyproject.toml").is_file():
+            return directory
+
+    return directory
 
 
 @dataclass
@@ -2771,6 +2922,7 @@ class Report:
 
     check: bool = False
     quiet: bool = False
+    verbose: bool = False
     change_count: int = 0
     same_count: int = 0
     failure_count: int = 0
@@ -2779,11 +2931,11 @@ class Report:
         """Increment the counter for successful reformatting. Write out a message."""
         if changed is Changed.YES:
             reformatted = "would reformat" if self.check else "reformatted"
-            if not self.quiet:
+            if self.verbose or not self.quiet:
                 out(f"{reformatted} {src}")
             self.change_count += 1
         else:
-            if not self.quiet:
+            if self.verbose:
                 if changed is Changed.NO:
                     msg = f"{src} already well formatted, good job."
                 else:
@@ -2796,6 +2948,10 @@ class Report:
         err(f"error: cannot format {src}: {message}")
         self.failure_count += 1
 
+    def path_ignored(self, path: Path, message: str) -> None:
+        if self.verbose:
+            out(f"{path} ignored: {message}", bold=False)
+
     @property
     def return_code(self) -> int:
         """Return the exit code that the app should use.
@@ -3156,26 +3312,24 @@ def get_cache_info(path: Path) -> CacheInfo:
     return stat.st_mtime, stat.st_size
 
 
-def filter_cached(
-    cache: Cache, sources: Iterable[Path]
-) -> Tuple[List[Path], List[Path]]:
-    """Split a list of paths into two.
+def filter_cached(cache: Cache, sources: Iterable[Path]) -> Tuple[Set[Path], Set[Path]]:
+    """Split an iterable of paths in `sources` into two sets.
 
-    The first list contains paths of files that modified on disk or are not in the
-    cache. The other list contains paths to non-modified files.
+    The first contains paths of files that modified on disk or are not in the
+    cache. The other contains paths to non-modified files.
     """
-    todo, done = [], []
+    todo, done = set(), set()
     for src in sources:
         src = src.resolve()
         if cache.get(src) != get_cache_info(src):
-            todo.append(src)
+            todo.add(src)
         else:
-            done.append(src)
+            done.add(src)
     return todo, done
 
 
 def write_cache(
-    cache: Cache, sources: List[Path], line_length: int, mode: FileMode
+    cache: Cache, sources: Iterable[Path], line_length: int, mode: FileMode
 ) -> None:
     """Update the cache file."""
     cache_file = get_cache_file(line_length, mode)