| | 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', |
| | 'platformdirs', |
| | 'jaraco', |
| | 'importlib_resources', |
| | 'more_itertools', |
| | ) |
| | VendorImporter(__name__, names).install() |
| |
|
