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344 lines
13 KiB
344 lines
13 KiB
6 years ago
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import os
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import tempfile
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from . import abc as resources_abc
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from contextlib import contextmanager, suppress
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from importlib import import_module
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from importlib.abc import ResourceLoader
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from io import BytesIO, TextIOWrapper
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from pathlib import Path
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from types import ModuleType
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from typing import Iterable, Iterator, Optional, Set, Union # noqa: F401
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from typing import cast
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from typing.io import BinaryIO, TextIO
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from zipimport import ZipImportError
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__all__ = [
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'Package',
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'Resource',
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'contents',
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'is_resource',
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'open_binary',
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'open_text',
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'path',
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'read_binary',
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'read_text',
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]
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Package = Union[str, ModuleType]
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Resource = Union[str, os.PathLike]
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def _get_package(package) -> ModuleType:
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"""Take a package name or module object and return the module.
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If a name, the module is imported. If the passed or imported module
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object is not a package, raise an exception.
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"""
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if hasattr(package, '__spec__'):
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if package.__spec__.submodule_search_locations is None:
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raise TypeError('{!r} is not a package'.format(
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package.__spec__.name))
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else:
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return package
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else:
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module = import_module(package)
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if module.__spec__.submodule_search_locations is None:
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raise TypeError('{!r} is not a package'.format(package))
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else:
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return module
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def _normalize_path(path) -> str:
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"""Normalize a path by ensuring it is a string.
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If the resulting string contains path separators, an exception is raised.
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"""
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parent, file_name = os.path.split(path)
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if parent:
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raise ValueError('{!r} must be only a file name'.format(path))
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else:
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return file_name
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def _get_resource_reader(
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package: ModuleType) -> Optional[resources_abc.ResourceReader]:
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# Return the package's loader if it's a ResourceReader. We can't use
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# a issubclass() check here because apparently abc.'s __subclasscheck__()
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# hook wants to create a weak reference to the object, but
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# zipimport.zipimporter does not support weak references, resulting in a
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# TypeError. That seems terrible.
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spec = package.__spec__
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if hasattr(spec.loader, 'get_resource_reader'):
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return cast(resources_abc.ResourceReader,
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spec.loader.get_resource_reader(spec.name))
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return None
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def _check_location(package):
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if package.__spec__.origin is None or not package.__spec__.has_location:
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raise FileNotFoundError(f'Package has no location {package!r}')
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def open_binary(package: Package, resource: Resource) -> BinaryIO:
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"""Return a file-like object opened for binary reading of the resource."""
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resource = _normalize_path(resource)
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package = _get_package(package)
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reader = _get_resource_reader(package)
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if reader is not None:
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return reader.open_resource(resource)
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_check_location(package)
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absolute_package_path = os.path.abspath(package.__spec__.origin)
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package_path = os.path.dirname(absolute_package_path)
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full_path = os.path.join(package_path, resource)
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try:
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return open(full_path, mode='rb')
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except OSError:
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# Just assume the loader is a resource loader; all the relevant
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# importlib.machinery loaders are and an AttributeError for
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# get_data() will make it clear what is needed from the loader.
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loader = cast(ResourceLoader, package.__spec__.loader)
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data = None
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if hasattr(package.__spec__.loader, 'get_data'):
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with suppress(OSError):
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data = loader.get_data(full_path)
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if data is None:
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package_name = package.__spec__.name
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message = '{!r} resource not found in {!r}'.format(
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resource, package_name)
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raise FileNotFoundError(message)
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else:
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return BytesIO(data)
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def open_text(package: Package,
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resource: Resource,
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encoding: str = 'utf-8',
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errors: str = 'strict') -> TextIO:
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"""Return a file-like object opened for text reading of the resource."""
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resource = _normalize_path(resource)
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package = _get_package(package)
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reader = _get_resource_reader(package)
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if reader is not None:
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return TextIOWrapper(reader.open_resource(resource), encoding, errors)
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_check_location(package)
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absolute_package_path = os.path.abspath(package.__spec__.origin)
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package_path = os.path.dirname(absolute_package_path)
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full_path = os.path.join(package_path, resource)
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try:
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return open(full_path, mode='r', encoding=encoding, errors=errors)
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except OSError:
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# Just assume the loader is a resource loader; all the relevant
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# importlib.machinery loaders are and an AttributeError for
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# get_data() will make it clear what is needed from the loader.
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loader = cast(ResourceLoader, package.__spec__.loader)
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data = None
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if hasattr(package.__spec__.loader, 'get_data'):
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with suppress(OSError):
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data = loader.get_data(full_path)
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if data is None:
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package_name = package.__spec__.name
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message = '{!r} resource not found in {!r}'.format(
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resource, package_name)
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raise FileNotFoundError(message)
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else:
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return TextIOWrapper(BytesIO(data), encoding, errors)
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def read_binary(package: Package, resource: Resource) -> bytes:
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"""Return the binary contents of the resource."""
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resource = _normalize_path(resource)
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package = _get_package(package)
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with open_binary(package, resource) as fp:
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return fp.read()
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def read_text(package: Package,
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resource: Resource,
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encoding: str = 'utf-8',
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errors: str = 'strict') -> str:
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"""Return the decoded string of the resource.
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The decoding-related arguments have the same semantics as those of
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bytes.decode().
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"""
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resource = _normalize_path(resource)
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package = _get_package(package)
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with open_text(package, resource, encoding, errors) as fp:
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return fp.read()
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@contextmanager
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def path(package: Package, resource: Resource) -> Iterator[Path]:
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"""A context manager providing a file path object to the resource.
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If the resource does not already exist on its own on the file system,
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a temporary file will be created. If the file was created, the file
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will be deleted upon exiting the context manager (no exception is
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raised if the file was deleted prior to the context manager
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exiting).
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"""
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resource = _normalize_path(resource)
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package = _get_package(package)
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reader = _get_resource_reader(package)
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if reader is not None:
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try:
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yield Path(reader.resource_path(resource))
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return
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except FileNotFoundError:
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pass
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else:
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_check_location(package)
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# Fall-through for both the lack of resource_path() *and* if
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# resource_path() raises FileNotFoundError.
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package_directory = Path(package.__spec__.origin).parent
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file_path = package_directory / resource
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if file_path.exists():
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yield file_path
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else:
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with open_binary(package, resource) as fp:
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data = fp.read()
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# Not using tempfile.NamedTemporaryFile as it leads to deeper 'try'
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# blocks due to the need to close the temporary file to work on
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# Windows properly.
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fd, raw_path = tempfile.mkstemp()
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try:
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os.write(fd, data)
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os.close(fd)
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yield Path(raw_path)
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finally:
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try:
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os.remove(raw_path)
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except FileNotFoundError:
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pass
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def is_resource(package: Package, name: str) -> bool:
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"""True if 'name' is a resource inside 'package'.
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Directories are *not* resources.
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"""
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package = _get_package(package)
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_normalize_path(name)
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reader = _get_resource_reader(package)
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if reader is not None:
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return reader.is_resource(name)
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try:
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package_contents = set(contents(package))
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except (NotADirectoryError, FileNotFoundError):
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return False
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if name not in package_contents:
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return False
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# Just because the given file_name lives as an entry in the package's
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# contents doesn't necessarily mean it's a resource. Directories are not
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# resources, so let's try to find out if it's a directory or not.
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path = Path(package.__spec__.origin).parent / name
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return path.is_file()
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def contents(package: Package) -> Iterable[str]:
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"""Return an iterable of entries in 'package'.
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Note that not all entries are resources. Specifically, directories are
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not considered resources. Use `is_resource()` on each entry returned here
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to check if it is a resource or not.
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"""
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package = _get_package(package)
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reader = _get_resource_reader(package)
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if reader is not None:
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return reader.contents()
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# Is the package a namespace package? By definition, namespace packages
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# cannot have resources. We could use _check_location() and catch the
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# exception, but that's extra work, so just inline the check.
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elif package.__spec__.origin is None or not package.__spec__.has_location:
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return ()
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else:
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package_directory = Path(package.__spec__.origin).parent
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return os.listdir(package_directory)
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# Private implementation of ResourceReader and get_resource_reader() called
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# from zipimport.c. Don't use these directly! We're implementing these in
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# Python because 1) it's easier, 2) zipimport may get rewritten in Python
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# itself at some point, so doing this all in C would difficult and a waste of
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# effort.
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class _ZipImportResourceReader(resources_abc.ResourceReader):
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"""Private class used to support ZipImport.get_resource_reader().
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This class is allowed to reference all the innards and private parts of
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the zipimporter.
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"""
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def __init__(self, zipimporter, fullname):
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self.zipimporter = zipimporter
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self.fullname = fullname
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def open_resource(self, resource):
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fullname_as_path = self.fullname.replace('.', '/')
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path = f'{fullname_as_path}/{resource}'
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try:
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return BytesIO(self.zipimporter.get_data(path))
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except OSError:
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raise FileNotFoundError(path)
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def resource_path(self, resource):
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# All resources are in the zip file, so there is no path to the file.
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# Raising FileNotFoundError tells the higher level API to extract the
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# binary data and create a temporary file.
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raise FileNotFoundError
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def is_resource(self, name):
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# Maybe we could do better, but if we can get the data, it's a
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# resource. Otherwise it isn't.
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fullname_as_path = self.fullname.replace('.', '/')
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path = f'{fullname_as_path}/{name}'
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try:
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self.zipimporter.get_data(path)
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except OSError:
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return False
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return True
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def contents(self):
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# This is a bit convoluted, because fullname will be a module path,
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# but _files is a list of file names relative to the top of the
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# archive's namespace. We want to compare file paths to find all the
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# names of things inside the module represented by fullname. So we
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# turn the module path of fullname into a file path relative to the
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# top of the archive, and then we iterate through _files looking for
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# names inside that "directory".
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fullname_path = Path(self.zipimporter.get_filename(self.fullname))
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relative_path = fullname_path.relative_to(self.zipimporter.archive)
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# Don't forget that fullname names a package, so its path will include
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# __init__.py, which we want to ignore.
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assert relative_path.name == '__init__.py'
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package_path = relative_path.parent
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subdirs_seen = set()
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for filename in self.zipimporter._files:
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try:
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relative = Path(filename).relative_to(package_path)
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except ValueError:
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continue
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# If the path of the file (which is relative to the top of the zip
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# namespace), relative to the package given when the resource
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# reader was created, has a parent, then it's a name in a
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# subdirectory and thus we skip it.
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parent_name = relative.parent.name
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if len(parent_name) == 0:
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yield relative.name
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elif parent_name not in subdirs_seen:
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subdirs_seen.add(parent_name)
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yield parent_name
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# Called from zipimport.c
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def _zipimport_get_resource_reader(zipimporter, fullname):
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try:
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if not zipimporter.is_package(fullname):
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return None
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except ZipImportError:
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return None
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return _ZipImportResourceReader(zipimporter, fullname)
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