Add importlib_resources to lib

Author: rembo10

lib/importlib_resources/__init__.py

@@ -0,0 +1,36 @@
+"""Read resources contained within a package."""
+
+from ._common import (
+    as_file,
+    files,
+    Package,
+)
+
+from ._legacy import (
+    contents,
+    open_binary,
+    read_binary,
+    open_text,
+    read_text,
+    is_resource,
+    path,
+    Resource,
+)
+
+from importlib_resources.abc import ResourceReader
+
+
+__all__ = [
+    'Package',
+    'Resource',
+    'ResourceReader',
+    'as_file',
+    'contents',
+    'files',
+    'is_resource',
+    'open_binary',
+    'open_text',
+    'path',
+    'read_binary',
+    'read_text',
+]

lib/importlib_resources/_adapters.py

@@ -0,0 +1,170 @@
+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)

lib/importlib_resources/_common.py

@@ -0,0 +1,104 @@
+import os
+import pathlib
+import tempfile
+import functools
+import contextlib
+import types
+import importlib
+
+from typing import Union, Optional
+from .abc import ResourceReader, Traversable
+
+from ._compat import wrap_spec
+
+Package = Union[types.ModuleType, str]
+
+
+def files(package):
+    # type: (Package) -> Traversable
+    """
+    Get a Traversable resource from a package
+    """
+    return from_package(get_package(package))
+
+
+def get_resource_reader(package):
+    # type: (types.ModuleType) -> Optional[ResourceReader]
+    """
+    Return the package's loader if it's a ResourceReader.
+    """
+    # We can't use
+    # a issubclass() check here because apparently abc.'s __subclasscheck__()
+    # hook wants to create a weak reference to the object, but
+    # zipimport.zipimporter does not support weak references, resulting in a
+    # TypeError.  That seems terrible.
+    spec = package.__spec__
+    reader = getattr(spec.loader, 'get_resource_reader', None)  # type: ignore
+    if reader is None:
+        return None
+    return reader(spec.name)  # type: ignore
+
+
+def resolve(cand):
+    # type: (Package) -> types.ModuleType
+    return cand if isinstance(cand, types.ModuleType) else importlib.import_module(cand)
+
+
+def get_package(package):
+    # type: (Package) -> types.ModuleType
+    """Take a package name or module object and return the module.
+
+    Raise an exception if the resolved module is not a package.
+    """
+    resolved = resolve(package)
+    if wrap_spec(resolved).submodule_search_locations is None:
+        raise TypeError(f'{package!r} is not a package')
+    return resolved
+
+
+def from_package(package):
+    """
+    Return a Traversable object for the given package.
+
+    """
+    spec = wrap_spec(package)
+    reader = spec.loader.get_resource_reader(spec.name)
+    return reader.files()
+
+
+@contextlib.contextmanager
+def _tempfile(reader, suffix=''):
+    # Not using tempfile.NamedTemporaryFile as it leads to deeper 'try'
+    # blocks due to the need to close the temporary file to work on Windows
+    # properly.
+    fd, raw_path = tempfile.mkstemp(suffix=suffix)
+    try:
+        try:
+            os.write(fd, reader())
+        finally:
+            os.close(fd)
+        del reader
+        yield pathlib.Path(raw_path)
+    finally:
+        try:
+            os.remove(raw_path)
+        except FileNotFoundError:
+            pass
+
+
+@functools.singledispatch
+def as_file(path):
+    """
+    Given a Traversable object, return that object as a
+    path on the local file system in a context manager.
+    """
+    return _tempfile(path.read_bytes, suffix=path.name)
+
+
+@as_file.register(pathlib.Path)
+@contextlib.contextmanager
+def _(path):
+    """
+    Degenerate behavior for pathlib.Path objects.
+    """
+    yield path