216 lines
7.0 KiB
Python
216 lines
7.0 KiB
Python
import os
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from . import abc as resources_abc
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from . import _common
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from ._common import as_file
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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 ContextManager, Iterable, Optional, Union
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from typing import cast
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from typing.io import BinaryIO, TextIO
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__all__ = [
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'Package',
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'Resource',
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'as_file',
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'contents',
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'files',
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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 _resolve(name) -> ModuleType:
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"""If name is a string, resolve to a module."""
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if hasattr(name, '__spec__'):
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return name
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return import_module(name)
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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 resolved module
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object is not a package, raise an exception.
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"""
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module = _resolve(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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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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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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absolute_package_path = os.path.abspath(
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package.__spec__.origin or 'non-existent file')
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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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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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return TextIOWrapper(
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open_binary(package, resource), encoding=encoding, errors=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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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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with open_text(package, resource, encoding, errors) as fp:
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return fp.read()
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def files(package: Package) -> resources_abc.Traversable:
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"""
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Get a Traversable resource from a package
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"""
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return _common.from_package(_get_package(package))
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def path(
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package: Package, resource: Resource,
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) -> 'ContextManager[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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reader = _get_resource_reader(_get_package(package))
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return (
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_path_from_reader(reader, resource)
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if reader else
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_common.as_file(files(package).joinpath(_normalize_path(resource)))
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)
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@contextmanager
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def _path_from_reader(reader, resource):
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norm_resource = _normalize_path(resource)
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with suppress(FileNotFoundError):
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yield Path(reader.resource_path(norm_resource))
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return
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opener_reader = reader.open_resource(norm_resource)
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with _common._tempfile(opener_reader.read, suffix=norm_resource) as res:
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yield res
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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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package_contents = set(contents(package))
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if name not in package_contents:
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return False
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return (_common.from_package(package) / name).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.
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namespace = (
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package.__spec__.origin is None or
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package.__spec__.origin == 'namespace'
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)
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if namespace or not package.__spec__.has_location:
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return ()
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return list(item.name for item in _common.from_package(package).iterdir())
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