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README: Add instructions for PyCharm (#81)
[etc/vim.git] / black.py
index 3bb83daef28c396cd7670503d7ad21c7d20336c2..9b144edb579d923d7479bdae8565f5df7507fd81 100644 (file)
--- a/black.py
+++ b/black.py
@@ -3,15 +3,19 @@
 import asyncio
 from asyncio.base_events import BaseEventLoop
 from concurrent.futures import Executor, ProcessPoolExecutor
+from enum import Enum
 from functools import partial, wraps
 import keyword
 import logging
+from multiprocessing import Manager
 import os
 from pathlib import Path
+import re
 import tokenize
 import signal
 import sys
 from typing import (
+    Any,
     Callable,
     Dict,
     Generic,
@@ -35,7 +39,7 @@ from blib2to3 import pygram, pytree
 from blib2to3.pgen2 import driver, token
 from blib2to3.pgen2.parse import ParseError
 
-__version__ = "18.3a4"
+__version__ = "18.4a0"
 DEFAULT_LINE_LENGTH = 88
 # types
 syms = pygram.python_symbols
@@ -92,6 +96,12 @@ class FormatOff(FormatError):
     """Found a comment like `# fmt: off` in the file."""
 
 
+class WriteBack(Enum):
+    NO = 0
+    YES = 1
+    DIFF = 2
+
+
 @click.command()
 @click.option(
     "-l",
@@ -105,16 +115,30 @@ class FormatOff(FormatError):
     "--check",
     is_flag=True,
     help=(
-        "Don't write back the files, just return the status.  Return code 0 "
+        "Don't write the files back, just return the status.  Return code 0 "
         "means nothing would change.  Return code 1 means some files would be "
         "reformatted.  Return code 123 means there was an internal error."
     ),
 )
+@click.option(
+    "--diff",
+    is_flag=True,
+    help="Don't write the files back, just output a diff for each file on stdout.",
+)
 @click.option(
     "--fast/--safe",
     is_flag=True,
     help="If --fast given, skip temporary sanity checks. [default: --safe]",
 )
+@click.option(
+    "-q",
+    "--quiet",
+    is_flag=True,
+    help=(
+        "Don't emit non-error messages to stderr. Errors are still emitted, "
+        "silence those with 2>/dev/null."
+    ),
+)
 @click.version_option(version=__version__)
 @click.argument(
     "src",
@@ -125,7 +149,13 @@ class FormatOff(FormatError):
 )
 @click.pass_context
 def main(
-    ctx: click.Context, line_length: int, check: bool, fast: bool, src: List[str]
+    ctx: click.Context,
+    line_length: int,
+    check: bool,
+    diff: bool,
+    fast: bool,
+    quiet: bool,
+    src: List[str],
 ) -> None:
     """The uncompromising code formatter."""
     sources: List[Path] = []
@@ -140,19 +170,30 @@ def main(
             sources.append(Path("-"))
         else:
             err(f"invalid path: {s}")
+    if check and diff:
+        exc = click.ClickException("Options --check and --diff are mutually exclusive")
+        exc.exit_code = 2
+        raise exc
+
+    if check:
+        write_back = WriteBack.NO
+    elif diff:
+        write_back = WriteBack.DIFF
+    else:
+        write_back = WriteBack.YES
     if len(sources) == 0:
         ctx.exit(0)
     elif len(sources) == 1:
         p = sources[0]
-        report = Report(check=check)
+        report = Report(check=check, quiet=quiet)
         try:
             if not p.is_file() and str(p) == "-":
                 changed = format_stdin_to_stdout(
-                    line_length=line_length, fast=fast, write_back=not check
+                    line_length=line_length, fast=fast, write_back=write_back
                 )
             else:
                 changed = format_file_in_place(
-                    p, line_length=line_length, fast=fast, write_back=not check
+                    p, line_length=line_length, fast=fast, write_back=write_back
                 )
             report.done(p, changed)
         except Exception as exc:
@@ -165,7 +206,7 @@ def main(
         try:
             return_code = loop.run_until_complete(
                 schedule_formatting(
-                    sources, line_length, not check, fast, loop, executor
+                    sources, line_length, write_back, fast, quiet, loop, executor
                 )
             )
         finally:
@@ -176,8 +217,9 @@ def main(
 async def schedule_formatting(
     sources: List[Path],
     line_length: int,
-    write_back: bool,
+    write_back: WriteBack,
     fast: bool,
+    quiet: bool,
     loop: BaseEventLoop,
     executor: Executor,
 ) -> int:
@@ -188,9 +230,15 @@ async def schedule_formatting(
     `line_length`, `write_back`, and `fast` options are passed to
     :func:`format_file_in_place`.
     """
+    lock = None
+    if write_back == WriteBack.DIFF:
+        # For diff output, we need locks to ensure we don't interleave output
+        # from different processes.
+        manager = Manager()
+        lock = manager.Lock()
     tasks = {
         src: loop.run_in_executor(
-            executor, format_file_in_place, src, line_length, fast, write_back
+            executor, format_file_in_place, src, line_length, fast, write_back, lock
         )
         for src in sources
     }
@@ -199,7 +247,7 @@ async def schedule_formatting(
     loop.add_signal_handler(signal.SIGTERM, cancel, _task_values)
     await asyncio.wait(tasks.values())
     cancelled = []
-    report = Report(check=not write_back)
+    report = Report(check=write_back is WriteBack.NO, quiet=quiet)
     for src, task in tasks.items():
         if not task.done():
             report.failed(src, "timed out, cancelling")
@@ -213,14 +261,19 @@ async def schedule_formatting(
             report.done(src, task.result())
     if cancelled:
         await asyncio.gather(*cancelled, loop=loop, return_exceptions=True)
-    else:
+    elif not quiet:
         out("All done! ✨ 🍰 ✨")
-    click.echo(str(report))
+    if not quiet:
+        click.echo(str(report))
     return report.return_code
 
 
 def format_file_in_place(
-    src: Path, line_length: int, fast: bool, write_back: bool = False
+    src: Path,
+    line_length: int,
+    fast: bool,
+    write_back: WriteBack = WriteBack.NO,
+    lock: Any = None,  # multiprocessing.Manager().Lock() is some crazy proxy
 ) -> bool:
     """Format file under `src` path. Return True if changed.
 
@@ -230,37 +283,53 @@ def format_file_in_place(
     with tokenize.open(src) as src_buffer:
         src_contents = src_buffer.read()
     try:
-        contents = format_file_contents(
+        dst_contents = format_file_contents(
             src_contents, line_length=line_length, fast=fast
         )
     except NothingChanged:
         return False
 
-    if write_back:
+    if write_back == write_back.YES:
         with open(src, "w", encoding=src_buffer.encoding) as f:
-            f.write(contents)
+            f.write(dst_contents)
+    elif write_back == write_back.DIFF:
+        src_name = f"{src.name}  (original)"
+        dst_name = f"{src.name}  (formatted)"
+        diff_contents = diff(src_contents, dst_contents, src_name, dst_name)
+        if lock:
+            lock.acquire()
+        try:
+            sys.stdout.write(diff_contents)
+        finally:
+            if lock:
+                lock.release()
     return True
 
 
 def format_stdin_to_stdout(
-    line_length: int, fast: bool, write_back: bool = False
+    line_length: int, fast: bool, write_back: WriteBack = WriteBack.NO
 ) -> bool:
     """Format file on stdin. Return True if changed.
 
     If `write_back` is True, write reformatted code back to stdout.
     `line_length` and `fast` arguments are passed to :func:`format_file_contents`.
     """
-    contents = sys.stdin.read()
+    src = sys.stdin.read()
     try:
-        contents = format_file_contents(contents, line_length=line_length, fast=fast)
+        dst = format_file_contents(src, line_length=line_length, fast=fast)
         return True
 
     except NothingChanged:
+        dst = src
         return False
 
     finally:
-        if write_back:
-            sys.stdout.write(contents)
+        if write_back == WriteBack.YES:
+            sys.stdout.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))
 
 
 def format_file_contents(
@@ -493,12 +562,13 @@ class BracketTracker:
             leaf.opening_bracket = opening_bracket
         leaf.bracket_depth = self.depth
         if self.depth == 0:
-            after_delim = is_split_after_delimiter(leaf, self.previous)
-            before_delim = is_split_before_delimiter(leaf, self.previous)
-            if after_delim > before_delim:
-                self.delimiters[id(leaf)] = after_delim
-            elif before_delim > after_delim and self.previous is not None:
-                self.delimiters[id(self.previous)] = before_delim
+            delim = is_split_before_delimiter(leaf, self.previous)
+            if delim and self.previous is not None:
+                self.delimiters[id(self.previous)] = delim
+            else:
+                delim = is_split_after_delimiter(leaf, self.previous)
+                if delim:
+                    self.delimiters[id(leaf)] = delim
         if leaf.type in OPENING_BRACKETS:
             self.bracket_match[self.depth, BRACKET[leaf.type]] = leaf
             self.depth += 1
@@ -1078,6 +1148,10 @@ class LineGenerator(Visitor[Line]):
                 yield from self.line()
                 yield from self.visit(node)
 
+            if node.type == token.ENDMARKER:
+                # somebody decided not to put a final `# fmt: on`
+                yield from self.line()
+
     def __attrs_post_init__(self) -> None:
         """You are in a twisty little maze of passages."""
         v = self.visit_stmt
@@ -1366,13 +1440,6 @@ def is_split_after_delimiter(leaf: Leaf, previous: Leaf = None) -> int:
     if leaf.type == token.COMMA:
         return COMMA_PRIORITY
 
-    if (
-        leaf.type in VARARGS
-        and leaf.parent
-        and leaf.parent.type in {syms.argument, syms.typedargslist}
-    ):
-        return MATH_PRIORITY
-
     return 0
 
 
@@ -1384,6 +1451,15 @@ def is_split_before_delimiter(leaf: Leaf, previous: Leaf = None) -> int:
 
     Higher numbers are higher priority.
     """
+    if (
+        leaf.type in VARARGS
+        and leaf.parent
+        and leaf.parent.type in {syms.argument, syms.typedargslist}
+    ):
+        # * and ** might also be MATH_OPERATORS but in this case they are not.
+        # Don't treat them as a delimiter.
+        return 0
+
     if (
         leaf.type in MATH_OPERATORS
         and leaf.parent
@@ -1481,7 +1557,12 @@ def generate_comments(leaf: Leaf) -> Iterator[Leaf]:
             raise FormatOn(consumed)
 
         if comment in {"# fmt: off", "# yapf: disable"}:
-            raise FormatOff(consumed)
+            if comment_type == STANDALONE_COMMENT:
+                raise FormatOff(consumed)
+
+            prev = preceding_leaf(leaf)
+            if not prev or prev.type in WHITESPACE:  # standalone comment in disguise
+                raise FormatOff(consumed)
 
         nlines = 0
 
@@ -1740,9 +1821,10 @@ def delimiter_split(line: Line, py36: bool = False) -> Iterator[Line]:
             current_line = Line(depth=line.depth, inside_brackets=line.inside_brackets)
     if current_line:
         if (
-            delimiter_priority == COMMA_PRIORITY
+            trailing_comma_safe
+            and delimiter_priority == COMMA_PRIORITY
             and current_line.leaves[-1].type != token.COMMA
-            and trailing_comma_safe
+            and current_line.leaves[-1].type != STANDALONE_COMMENT
         ):
             current_line.append(Leaf(token.COMMA, ","))
         yield current_line
@@ -1839,10 +1921,21 @@ def normalize_string_quotes(leaf: Leaf) -> None:
     if first_quote_pos == -1:
         return  # There's an internal error
 
+    prefix = leaf.value[:first_quote_pos]
     body = leaf.value[first_quote_pos + len(orig_quote):-len(orig_quote)]
-    new_body = body.replace(f"\\{orig_quote}", orig_quote).replace(
-        new_quote, f"\\{new_quote}"
-    )
+    unescaped_new_quote = re.compile(r"(([^\\]|^)(\\\\)*)" + new_quote)
+    escaped_orig_quote = re.compile(r"\\(\\\\)*" + orig_quote)
+    if "r" in prefix.casefold():
+        if unescaped_new_quote.search(body):
+            # There's at least one unescaped new_quote in this raw string
+            # so converting is impossible
+            return
+
+        # Do not introduce or remove backslashes in raw strings
+        new_body = body
+    else:
+        new_body = escaped_orig_quote.sub(f"\\1{orig_quote}", body)
+        new_body = unescaped_new_quote.sub(f"\\1\\\\{new_quote}", new_body)
     if new_quote == '"""' and new_body[-1] == '"':
         # edge case:
         new_body = new_body[:-1] + '\\"'
@@ -1854,7 +1947,6 @@ def normalize_string_quotes(leaf: Leaf) -> None:
     if new_escape_count == orig_escape_count and orig_quote == '"':
         return  # Prefer double quotes
 
-    prefix = leaf.value[:first_quote_pos]
     leaf.value = f"{prefix}{new_quote}{new_body}{new_quote}"
 
 
@@ -1908,6 +2000,7 @@ def gen_python_files_in_dir(path: Path) -> Iterator[Path]:
 class Report:
     """Provides a reformatting counter. Can be rendered with `str(report)`."""
     check: bool = False
+    quiet: bool = False
     change_count: int = 0
     same_count: int = 0
     failure_count: int = 0
@@ -1916,10 +2009,12 @@ class Report:
         """Increment the counter for successful reformatting. Write out a message."""
         if changed:
             reformatted = "would reformat" if self.check else "reformatted"
-            out(f"{reformatted} {src}")
+            if not self.quiet:
+                out(f"{reformatted} {src}")
             self.change_count += 1
         else:
-            out(f"{src} already well formatted, good job.", bold=False)
+            if not self.quiet:
+                out(f"{src} already well formatted, good job.", bold=False)
             self.same_count += 1
 
     def failed(self, src: Path, message: str) -> None:
@@ -2064,7 +2159,8 @@ def dump_to_file(*output: str) -> str:
     ) as f:
         for lines in output:
             f.write(lines)
-            f.write("\n")
+            if lines and lines[-1] != "\n":
+                f.write("\n")
     return f.name