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from contextlib import suppress
from io import TextIOWrapper
from . import abc
class SpecLoaderAdapter:
"""
Adapt a package spec to adapt the underlying loader.
"""
def __init__(self, spec, adapter=lambda spec: spec.loader):
self.spec = spec
self.loader = adapter(spec)
def __getattr__(self, name):
return getattr(self.spec, name)
class TraversableResourcesLoader:
"""
Adapt a loader to provide TraversableResources.
"""
def __init__(self, spec):
self.spec = spec
def get_resource_reader(self, name):
return CompatibilityFiles(self.spec)._native()
def _io_wrapper(file, mode='r', *args, **kwargs):
if mode == 'r':
return TextIOWrapper(file, *args, **kwargs)
elif mode == 'rb':
return file
raise ValueError(
"Invalid mode value '{}', only 'r' and 'rb' are supported".format(mode)
)
class CompatibilityFiles:
"""
Adapter for an existing or non-existent resource reader
to provide a compatibility .files().
"""
class SpecPath(abc.Traversable):
"""
Path tied to a module spec.
Can be read and exposes the resource reader children.
"""
def __init__(self, spec, reader):
self._spec = spec
self._reader = reader
def iterdir(self):
if not self._reader:
return iter(())
return iter(
CompatibilityFiles.ChildPath(self._reader, path)
for path in self._reader.contents()
)
def is_file(self):
return False
is_dir = is_file
def joinpath(self, other):
if not self._reader:
return CompatibilityFiles.OrphanPath(other)
return CompatibilityFiles.ChildPath(self._reader, other)
@property
def name(self):
return self._spec.name
def open(self, mode='r', *args, **kwargs):
return _io_wrapper(self._reader.open_resource(None), mode, *args, **kwargs)
class ChildPath(abc.Traversable):
"""
Path tied to a resource reader child.
Can be read but doesn't expose any meaningful children.
"""
def __init__(self, reader, name):
self._reader = reader
self._name = name
def iterdir(self):
return iter(())
def is_file(self):
return self._reader.is_resource(self.name)
def is_dir(self):
return not self.is_file()
def joinpath(self, other):
return CompatibilityFiles.OrphanPath(self.name, other)
@property
def name(self):
return self._name
def open(self, mode='r', *args, **kwargs):
return _io_wrapper(
self._reader.open_resource(self.name), mode, *args, **kwargs
)
class OrphanPath(abc.Traversable):
"""
Orphan path, not tied to a module spec or resource reader.
Can't be read and doesn't expose any meaningful children.
"""
def __init__(self, *path_parts):
if len(path_parts) < 1:
raise ValueError('Need at least one path part to construct a path')
self._path = path_parts
def iterdir(self):
return iter(())
def is_file(self):
return False
is_dir = is_file
def joinpath(self, other):
return CompatibilityFiles.OrphanPath(*self._path, other)
@property
def name(self):
return self._path[-1]
def open(self, mode='r', *args, **kwargs):
raise FileNotFoundError("Can't open orphan path")
def __init__(self, spec):
self.spec = spec
@property
def _reader(self):
with suppress(AttributeError):
return self.spec.loader.get_resource_reader(self.spec.name)
def _native(self):
"""
Return the native reader if it supports files().
"""
reader = self._reader
return reader if hasattr(reader, 'files') else self
def __getattr__(self, attr):
return getattr(self._reader, attr)
def files(self):
return CompatibilityFiles.SpecPath(self.spec, self._reader)
def wrap_spec(package):
"""
Construct a package spec with traversable compatibility
on the spec/loader/reader.
"""
return SpecLoaderAdapter(package.__spec__, TraversableResourcesLoader)
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