import imp

import os

import sys

def module_has_submodule(package, module_name):

    """See if 'module' is in 'package'."""

    name = ".".join([package.__name__, module_name])

    if name in sys.modules:

        return True

    for finder in sys.meta_path:

        if finder.find_module(name):

            return True

    for entry in package.__path__:  # No __path__, then not a package.

        try:

            # Try the cached finder.

            finder = sys.path_importer_cache[entry]

            if finder is None:

                # Implicit import machinery should be used.

                try:

                    file_, _, _ = imp.find_module(module_name, [entry])

                    if file_:

                        file_.close()

                    return True

                except ImportError:

                    continue

            # Else see if the finder knows of a loader.

            elif finder.find_module(name):

                return True

            else:

                continue

        except KeyError:

            # No cached finder, so try and make one.

            for hook in sys.path_hooks:

                try:

                    finder = hook(entry)

                    # XXX Could cache in sys.path_importer_cache

                    if finder.find_module(name):

                        return True

                    else:

                        # Once a finder is found, stop the search.

                        break

                except ImportError:

                    # Continue the search for a finder.

                    continue

            else:

                # No finder found.

                # Try the implicit import machinery if searching a directory.

                if os.path.isdir(entry):

                    try:

                        file_, _, _ = imp.find_module(module_name, [entry])

                        if file_:

                            file_.close()

                        return True

                    except ImportError:

                        pass

                # XXX Could insert None or NullImporter

    else:

        # Exhausted the search, so the module cannot be found.

        return False