You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
73 lines
2.3 KiB
73 lines
2.3 KiB
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', 'appdirs'
|
|
VendorImporter(__name__, names).install()
|
|
|