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Preserve line endings when formatting a file in place (#288)
[etc/vim.git] / black.py
index 8ac6d87e7c25d35ed4ecde193bf47f6b3a81006b..36e49b026a53492ba635621353c2e37ffa2b9520 100644 (file)
--- a/black.py
+++ b/black.py
@@ -4,6 +4,7 @@ from asyncio.base_events import BaseEventLoop
 from concurrent.futures import Executor, ProcessPoolExecutor
 from enum import Enum, Flag
 from functools import partial, wraps
+import io
 import keyword
 import logging
 from multiprocessing import Manager
@@ -119,6 +120,13 @@ 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
@@ -132,6 +140,19 @@ class FileMode(Flag):
     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()
 @click.option(
@@ -218,6 +239,15 @@ class FileMode(Flag):
         "silence those with 2>/dev/null."
     ),
 )
+@click.option(
+    "-v",
+    "--verbose",
+    is_flag=True,
+    help=(
+        "Also emit messages to stderr about files that were not changed or were "
+        "ignored due to --exclude=."
+    ),
+)
 @click.version_option(version=__version__)
 @click.argument(
     "src",
@@ -237,11 +267,17 @@ def main(
     py36: bool,
     skip_string_normalization: bool,
     quiet: bool,
+    verbose: bool,
     include: str,
     exclude: str,
     src: List[str],
 ) -> None:
     """The uncompromising code formatter."""
+    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: List[Path] = []
     try:
         include_regex = re.compile(include)
@@ -253,32 +289,18 @@ def main(
     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, include_regex, exclude_regex))
-        elif p.is_file():
+            sources.extend(
+                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("-"))
         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
-    if skip_string_normalization:
-        mode |= FileMode.NO_STRING_NORMALIZATION
-    report = Report(check=check, quiet=quiet)
     if len(sources) == 0:
         out("No paths given. Nothing to do 😴")
         ctx.exit(0)
@@ -342,8 +364,8 @@ 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,
@@ -444,8 +466,9 @@ def format_file_in_place(
     """
     if src.suffix == ".pyi":
         mode |= FileMode.PYI
-    with tokenize.open(src) as src_buffer:
-        src_contents = src_buffer.read()
+
+    with open(src, "rb") as buf:
+        newline, encoding, src_contents = prepare_input(buf.read())
     try:
         dst_contents = format_file_contents(
             src_contents, line_length=line_length, fast=fast, mode=mode
@@ -454,7 +477,7 @@ 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)"
@@ -463,7 +486,14 @@ def format_file_in_place(
         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()
@@ -482,7 +512,7 @@ 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()
+    newline, encoding, src = prepare_input(sys.stdin.buffer.read())
     dst = src
     try:
         dst = format_file_contents(src, line_length=line_length, fast=fast, mode=mode)
@@ -493,11 +523,25 @@ def format_stdin_to_stdout(
 
     finally:
         if write_back == WriteBack.YES:
-            sys.stdout.write(dst)
+            f = io.TextIOWrapper(
+                sys.stdout.buffer,
+                encoding=encoding,
+                newline=newline,
+                write_through=True,
+            )
+            f.write(dst)
+            f.detach()
         elif write_back == WriteBack.DIFF:
             src_name = "<stdin>  (original)"
             dst_name = "<stdin>  (formatted)"
-            sys.stdout.write(diff(src, dst, src_name, dst_name))
+            f = io.TextIOWrapper(
+                sys.stdout.buffer,
+                encoding=encoding,
+                newline=newline,
+                write_through=True,
+            )
+            f.write(diff(src, dst, src_name, dst_name))
+            f.detach()
 
 
 def format_file_contents(
@@ -558,6 +602,19 @@ def format_str(
     return dst_contents
 
 
+def prepare_input(src: bytes) -> Tuple[str, str, str]:
+    """Analyze `src` and return a tuple of (newline, encoding, decoded_contents)
+
+    Where `newline` is either CRLF or LF, and `decoded_contents` is decoded with
+    universal newlines (i.e. only LF).
+    """
+    srcbuf = io.BytesIO(src)
+    encoding, lines = tokenize.detect_encoding(srcbuf.readline)
+    newline = "\r\n" if b"\r\n" == lines[0][-2:] else "\n"
+    srcbuf.seek(0)
+    return newline, encoding, io.TextIOWrapper(srcbuf, encoding).read()
+
+
 GRAMMARS = [
     pygram.python_grammar_no_print_statement_no_exec_statement,
     pygram.python_grammar_no_print_statement,
@@ -569,8 +626,7 @@ 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
+        src_txt += "\n"
     for grammar in GRAMMARS:
         drv = driver.Driver(grammar, pytree.convert)
         try:
@@ -2792,21 +2848,29 @@ def get_future_imports(node: Node) -> Set[str]:
 
 
 def gen_python_files_in_dir(
-    path: Path, include: Pattern[str], exclude: Pattern[str]
+    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.
+
+    `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().as_posix()
+        normalized_path = "/" + child.resolve().relative_to(root).as_posix()
         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 --exclude={exclude.pattern}")
             continue
 
         if child.is_dir():
-            yield from gen_python_files_in_dir(child, include, exclude)
+            yield from gen_python_files_in_dir(child, root, include, exclude, report)
 
         elif child.is_file():
             include_match = include.search(normalized_path)
@@ -2814,12 +2878,42 @@ def gen_python_files_in_dir(
                 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
 class Report:
     """Provides a reformatting counter. Can be rendered with `str(report)`."""
 
     check: bool = False
     quiet: bool = False
+    verbose: bool = False
     change_count: int = 0
     same_count: int = 0
     failure_count: int = 0
@@ -2828,11 +2922,11 @@ 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:
@@ -2845,6 +2939,10 @@ 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.