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import functools
import pathlib
from contextlib import suppress
from types import SimpleNamespace
from .. import readers, _adapters
def _block_standard(reader_getter):
"""
Wrap _adapters.TraversableResourcesLoader.get_resource_reader
and intercept any standard library readers.
"""
@functools.wraps(reader_getter)
def wrapper(*args, **kwargs):
"""
If the reader is from the standard library, return None to allow
allow likely newer implementations in this library to take precedence.
"""
try:
reader = reader_getter(*args, **kwargs)
except NotADirectoryError:
# MultiplexedPath may fail on zip subdirectory
return
# Python 3.10+
mod_name = reader.__class__.__module__
if mod_name.startswith('importlib.') and mod_name.endswith('readers'):
return
# Python 3.8, 3.9
if isinstance(reader, _adapters.CompatibilityFiles) and (
reader.spec.loader.__class__.__module__.startswith('zipimport')
or reader.spec.loader.__class__.__module__.startswith(
'_frozen_importlib_external'
)
):
return
return reader
return wrapper
def _skip_degenerate(reader):
"""
Mask any degenerate reader. Ref #298.
"""
is_degenerate = (
isinstance(reader, _adapters.CompatibilityFiles) and not reader._reader
)
return reader if not is_degenerate else None
class TraversableResourcesLoader(_adapters.TraversableResourcesLoader):
"""
Adapt loaders to provide TraversableResources and other
compatibility.
Ensures the readers from importlib_resources are preferred
over stdlib readers.
"""
def get_resource_reader(self, name):
return (
_skip_degenerate(_block_standard(super().get_resource_reader)(name))
or self._standard_reader()
or super().get_resource_reader(name)
)
def _standard_reader(self):
return self._zip_reader() or self._namespace_reader() or self._file_reader()
def _zip_reader(self):
with suppress(AttributeError):
return readers.ZipReader(self.spec.loader, self.spec.name)
def _namespace_reader(self):
with suppress(AttributeError, ValueError):
return readers.NamespaceReader(self.spec.submodule_search_locations)
def _file_reader(self):
try:
path = pathlib.Path(self.spec.origin)
except TypeError:
return None
if path.exists():
return readers.FileReader(SimpleNamespace(path=path))
def wrap_spec(package):
"""
Override _adapters.wrap_spec to use TraversableResourcesLoader
from above. Ensures that future behavior is always available on older
Pythons.
"""
return _adapters.SpecLoaderAdapter(package.__spec__, TraversableResourcesLoader)