Method get_toplevel_possibilities

mypy/modulefinder.py:278–307

Find which elements of lib_path could contain a particular top-level module. In practice, almost all modules can be routed to the correct entry in lib_path by looking at just the first component of the module name. We take advantage of this by enumerating the contents of al

(self, lib_path: tuple[str, ...], id: str)

        return dirs

    def get_toplevel_possibilities(self, lib_path: tuple[str, ...], id: str) -> list[str]:
        """Find which elements of lib_path could contain a particular top-level module.

        In practice, almost all modules can be routed to the correct entry in
        lib_path by looking at just the first component of the module name.

        We take advantage of this by enumerating the contents of all of the
        directories on the lib_path and building a map of which entries in
        the lib_path could contain each potential top-level module that appears.
        """

        if lib_path in self.initial_components:
            return self.initial_components[lib_path].get(id, [])

        # Enumerate all the files in the directories on lib_path and produce the map
        components: dict[str, list[str]] = {}
        for dir in lib_path:
            try:
                contents = self.fscache.listdir(dir)
            except OSError:
                contents = []
            # False positives are fine for correctness here, since we will check
            # precisely later, so we only look at the root of every filename without
            # any concern for the exact details.
            for name in contents:
                name = os.path.splitext(name)[0]
                components.setdefault(name, []).append(dir)

        self.initial_components[lib_path] = components
        return components.get(id, [])

    def find_module(self, id: str, *, fast_path: bool = False) -> ModuleSearchResult:
        """Return the path of the module source file or why it wasn't found.