init

.venv/lib/python3.8/site-packages/black/cache.py

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+"""Caching of formatted files with feature-based invalidation."""
+
+import os
+import pickle
+from pathlib import Path
+import tempfile
+from typing import Dict, Iterable, Set, Tuple
+
+from platformdirs import user_cache_dir
+
+from black.mode import Mode
+
+from _black_version import version as __version__
+
+
+# types
+Timestamp = float
+FileSize = int
+CacheInfo = Tuple[Timestamp, FileSize]
+Cache = Dict[str, CacheInfo]
+
+
+def get_cache_dir() -> Path:
+    """Get the cache directory used by black.
+
+    Users can customize this directory on all systems using `BLACK_CACHE_DIR`
+    environment variable. By default, the cache directory is the user cache directory
+    under the black application.
+
+    This result is immediately set to a constant `black.cache.CACHE_DIR` as to avoid
+    repeated calls.
+    """
+    # NOTE: Function mostly exists as a clean way to test getting the cache directory.
+    default_cache_dir = user_cache_dir("black", version=__version__)
+    cache_dir = Path(os.environ.get("BLACK_CACHE_DIR", default_cache_dir))
+    return cache_dir
+
+
+CACHE_DIR = get_cache_dir()
+
+
+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.
+    """
+    cache_file = get_cache_file(mode)
+    if not cache_file.exists():
+        return {}
+
+    with cache_file.open("rb") as fobj:
+        try:
+            cache: Cache = pickle.load(fobj)
+        except (pickle.UnpicklingError, ValueError, IndexError):
+            return {}
+
+    return cache
+
+
+def get_cache_file(mode: Mode) -> Path:
+    return CACHE_DIR / f"cache.{mode.get_cache_key()}.pickle"
+
+
+def get_cache_info(path: Path) -> CacheInfo:
+    """Return the information used to check if a file is already formatted or not."""
+    stat = path.stat()
+    return stat.st_mtime, stat.st_size
+
+
+def filter_cached(cache: Cache, sources: Iterable[Path]) -> Tuple[Set[Path], Set[Path]]:
+    """Split an iterable of paths in `sources` into two sets.
+
+    The first contains paths of files that modified on disk or are not in the
+    cache. The other contains paths to non-modified files.
+    """
+    todo, done = set(), set()
+    for src in sources:
+        res_src = src.resolve()
+        if cache.get(str(res_src)) != get_cache_info(res_src):
+            todo.add(src)
+        else:
+            done.add(src)
+    return todo, done
+
+
+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,
+            **{str(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=4)
+        os.replace(f.name, cache_file)
+    except OSError:
+        pass