Class FindModuleCache

mypy/modulefinder.py:172–674

Module finder with integrated cache. Module locations and some intermediate results are cached internally and can be cleared with the clear() method. All file system accesses are performed through a FileSystemCache, which is not ever cleared by this class. If necessary it must be

class FindModuleCache:
    """Module finder with integrated cache.

    Module locations and some intermediate results are cached internally
    and can be cleared with the clear() method.

    All file system accesses are performed through a FileSystemCache,
    which is not ever cleared by this class. If necessary it must be
    cleared by client code.
    """

    def __init__(
        self,
        search_paths: SearchPaths,
        fscache: FileSystemCache | None,
        options: Options | None,
        stdlib_py_versions: StdlibVersions | None = None,
        source_set: BuildSourceSet | None = None,
    ) -> None:
        self.search_paths = search_paths
        self.source_set = source_set
        self.fscache = fscache or FileSystemCache()
        # Cache for get_toplevel_possibilities:
        # search_paths -> (toplevel_id -> list(package_dirs))
        self.initial_components: dict[tuple[str, ...], dict[str, list[str]]] = {}
        # Cache find_module: id -> result
        self.results: dict[str, ModuleSearchResult] = {}
        self.ns_ancestors: dict[str, str] = {}
        self.options = options
        custom_typeshed_dir = None
        if options:
            custom_typeshed_dir = options.custom_typeshed_dir
        self.stdlib_py_versions = stdlib_py_versions or load_stdlib_py_versions(
            custom_typeshed_dir
        )

    def clear(self) -> None:
        self.results.clear()
        self.initial_components.clear()
        self.ns_ancestors.clear()

    def find_module_via_source_set(self, id: str) -> ModuleSearchResult | None:
        """Fast path to find modules by looking through the input sources

        This is only used when --fast-module-lookup is passed on the command line."""
        if not self.source_set:
            return None

        p = self.source_set.source_modules.get(id, None)
        if p and self.fscache.isfile(p):
            # We need to make sure we still have __init__.py all the way up
            # otherwise we might have false positives compared to slow path
            # in case of deletion of init files, which is covered by some tests.
            # TODO: are there some combination of flags in which this check should be skipped?
            d = os.path.dirname(p)
            for _ in range(id.count(".")):
                if not any(
                    self.fscache.isfile(os_path_join(d, "__init__" + x)) for x in PYTHON_EXTENSIONS