| import importlib.util |
| import sys |
| |
| |
| class VendorImporter: |
| """ |
| A PEP 302 meta path importer for finding optionally-vendored |
| or otherwise naturally-installed packages from root_name. |
| """ |
| |
| def __init__(self, root_name, vendored_names=(), vendor_pkg=None): |
| self.root_name = root_name |
| self.vendored_names = set(vendored_names) |
| self.vendor_pkg = vendor_pkg or root_name.replace('extern', '_vendor') |
| |
| @property |
| def search_path(self): |
| """ |
| Search first the vendor package then as a natural package. |
| """ |
| yield self.vendor_pkg + '.' |
| yield '' |
| |
| def _module_matches_namespace(self, fullname): |
| """Figure out if the target module is vendored.""" |
| root, base, target = fullname.partition(self.root_name + '.') |
| return not root and any(map(target.startswith, self.vendored_names)) |
| |
| def load_module(self, fullname): |
| """ |
| Iterate over the search path to locate and load fullname. |
| """ |
| root, base, target = fullname.partition(self.root_name + '.') |
| for prefix in self.search_path: |
| try: |
| extant = prefix + target |
| __import__(extant) |
| mod = sys.modules[extant] |
| sys.modules[fullname] = mod |
| return mod |
| except ImportError: |
| pass |
| else: |
| raise ImportError( |
| "The '{target}' package is required; " |
| "normally this is bundled with this package so if you get " |
| "this warning, consult the packager of your " |
| "distribution.".format(**locals()) |
| ) |
| |
| def create_module(self, spec): |
| return self.load_module(spec.name) |
| |
| def exec_module(self, module): |
| pass |
| |
| def find_spec(self, fullname, path=None, target=None): |
| """Return a module spec for vendored names.""" |
| return ( |
| importlib.util.spec_from_loader(fullname, self) |
| if self._module_matches_namespace(fullname) else None |
| ) |
| |
| def install(self): |
| """ |
| Install this importer into sys.meta_path if not already present. |
| """ |
| if self not in sys.meta_path: |
| sys.meta_path.append(self) |
| |
| |
| names = ( |
| 'packaging', 'pyparsing', 'ordered_set', 'more_itertools', 'importlib_metadata', |
| 'zipp', 'importlib_resources', 'jaraco', 'typing_extensions', 'tomli', |
| ) |
| VendorImporter(__name__, names, 'setuptools._vendor').install() |
