codekingpro/portable-devtools

1import importlib.util2import sys3 4 5class VendorImporter:6    """7    A PEP 302 meta path importer for finding optionally-vendored8    or otherwise naturally-installed packages from root_name.9    """10 11    def __init__(self, root_name, vendored_names=(), vendor_pkg=None):12        self.root_name = root_name13        self.vendored_names = set(vendored_names)14        self.vendor_pkg = vendor_pkg or root_name.replace('extern', '_vendor')15 16    @property17    def search_path(self):18        """19        Search first the vendor package then as a natural package.20        """21        yield self.vendor_pkg + '.'22        yield ''23 24    def _module_matches_namespace(self, fullname):25        """Figure out if the target module is vendored."""26        root, base, target = fullname.partition(self.root_name + '.')27        return not root and any(map(target.startswith, self.vendored_names))28 29    def load_module(self, fullname):30        """31        Iterate over the search path to locate and load fullname.32        """33        root, base, target = fullname.partition(self.root_name + '.')34        for prefix in self.search_path:35            try:36                extant = prefix + target37                __import__(extant)38                mod = sys.modules[extant]39                sys.modules[fullname] = mod40                return mod41            except ImportError:42                pass43        else:44            raise ImportError(45                "The '{target}' package is required; "46                "normally this is bundled with this package so if you get "47                "this warning, consult the packager of your "48                "distribution.".format(**locals())49            )50 51    def create_module(self, spec):52        return self.load_module(spec.name)53 54    def exec_module(self, module):55        pass56 57    def find_spec(self, fullname, path=None, target=None):58        """Return a module spec for vendored names."""59        return (60            importlib.util.spec_from_loader(fullname, self)61            if self._module_matches_namespace(fullname)62            else None63        )64 65    def install(self):66        """67        Install this importer into sys.meta_path if not already present.68        """69        if self not in sys.meta_path:70            sys.meta_path.append(self)71 72 73names = (74    'packaging',75    'ordered_set',76    'more_itertools',77    'importlib_metadata',78    'zipp',79    'importlib_resources',80    'jaraco',81    'typing_extensions',82    'tomli',83    'backports',84)85VendorImporter(__name__, names, 'setuptools._vendor').install()86