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""" | |
Interface adapters for low-level readers. | |
""" | |
import abc | |
import io | |
import itertools | |
from typing import BinaryIO, List | |
from .abc import Traversable, TraversableResources | |
class SimpleReader(abc.ABC): | |
""" | |
The minimum, low-level interface required from a resource | |
provider. | |
""" | |
def package(self) -> str: | |
""" | |
The name of the package for which this reader loads resources. | |
""" | |
def children(self) -> List['SimpleReader']: | |
""" | |
Obtain an iterable of SimpleReader for available | |
child containers (e.g. directories). | |
""" | |
def resources(self) -> List[str]: | |
""" | |
Obtain available named resources for this virtual package. | |
""" | |
def open_binary(self, resource: str) -> BinaryIO: | |
""" | |
Obtain a File-like for a named resource. | |
""" | |
def name(self): | |
return self.package.split('.')[-1] | |
class ResourceContainer(Traversable): | |
""" | |
Traversable container for a package's resources via its reader. | |
""" | |
def __init__(self, reader: SimpleReader): | |
self.reader = reader | |
def is_dir(self): | |
return True | |
def is_file(self): | |
return False | |
def iterdir(self): | |
files = (ResourceHandle(self, name) for name in self.reader.resources) | |
dirs = map(ResourceContainer, self.reader.children()) | |
return itertools.chain(files, dirs) | |
def open(self, *args, **kwargs): | |
raise IsADirectoryError() | |
class ResourceHandle(Traversable): | |
""" | |
Handle to a named resource in a ResourceReader. | |
""" | |
def __init__(self, parent: ResourceContainer, name: str): | |
self.parent = parent | |
self.name = name # type: ignore[misc] | |
def is_file(self): | |
return True | |
def is_dir(self): | |
return False | |
def open(self, mode='r', *args, **kwargs): | |
stream = self.parent.reader.open_binary(self.name) | |
if 'b' not in mode: | |
stream = io.TextIOWrapper(stream, *args, **kwargs) | |
return stream | |
def joinpath(self, name): | |
raise RuntimeError("Cannot traverse into a resource") | |
class TraversableReader(TraversableResources, SimpleReader): | |
""" | |
A TraversableResources based on SimpleReader. Resource providers | |
may derive from this class to provide the TraversableResources | |
interface by supplying the SimpleReader interface. | |
""" | |
def files(self): | |
return ResourceContainer(self) | |