modulegraph.py 文件源码

def _find_module(self, name, path, parent=None):
        """
        Get a 3-tuple detailing the physical location of the Python module with
        the passed name if that module is found *or* raise `ImportError`
        otherwise.

        This high-level method wraps the low-level `modulegraph.find_module()`
        function with additional support for graph-based module caching.

        Parameters
        ----------
        name : str
            Fully-qualified name of the Python module to be found.
        path : list
            List of the absolute paths of all directories to search for this
            module *or* `None` if the default path list `self.path` is to be
            searched.
        parent : Node
            Optional parent module of this module if this module is a submodule
            of another module *or* `None` if this module is a top-level module.

        Returns
        ----------
        (file_handle, filename, metadata)
            See `modulegraph._find_module()` for details.
        """
        if parent is not None:
            # assert path is not None
            fullname = parent.identifier + '.' + name
        else:
            fullname = name

        node = self.findNode(fullname)
        if node is not None:
            self.msg(3, "find_module: already included?", node)
            raise ImportError(name)

        if path is None:
            if name in sys.builtin_module_names:
                return (None, None, ("", "", imp.C_BUILTIN))

            path = self.path

        return self._find_module_path(fullname, name, path)