codekingpro/portable-devtools

1"""2Interface adapters for low-level readers.3"""4 5import abc6import io7import itertools8from typing import BinaryIO9 10from .abc import Traversable, TraversableResources11 12 13class SimpleReader(abc.ABC):14    """15    The minimum, low-level interface required from a resource16    provider.17    """18 19    @property20    @abc.abstractmethod21    def package(self) -> str:22        """23        The name of the package for which this reader loads resources.24        """25 26    @abc.abstractmethod27    def children(self) -> list['SimpleReader']:28        """29        Obtain an iterable of SimpleReader for available30        child containers (e.g. directories).31        """32 33    @abc.abstractmethod34    def resources(self) -> list[str]:35        """36        Obtain available named resources for this virtual package.37        """38 39    @abc.abstractmethod40    def open_binary(self, resource: str) -> BinaryIO:41        """42        Obtain a File-like for a named resource.43        """44 45    @property46    def name(self):47        return self.package.split('.')[-1]48 49 50class ResourceContainer(Traversable):51    """52    Traversable container for a package's resources via its reader.53    """54 55    def __init__(self, reader: SimpleReader):56        self.reader = reader57 58    def is_dir(self):59        return True60 61    def is_file(self):62        return False63 64    def iterdir(self):65        files = (ResourceHandle(self, name) for name in self.reader.resources)66        dirs = map(ResourceContainer, self.reader.children())67        return itertools.chain(files, dirs)68 69    def open(self, *args, **kwargs):70        raise IsADirectoryError()71 72 73class ResourceHandle(Traversable):74    """75    Handle to a named resource in a ResourceReader.76    """77 78    def __init__(self, parent: ResourceContainer, name: str):79        self.parent = parent80        self.name = name  # type: ignore[misc]81 82    def is_file(self):83        return True84 85    def is_dir(self):86        return False87 88    def open(self, mode='r', *args, **kwargs):89        stream = self.parent.reader.open_binary(self.name)90        if 'b' not in mode:91            stream = io.TextIOWrapper(stream, *args, **kwargs)92        return stream93 94    def joinpath(self, name):95        raise RuntimeError("Cannot traverse into a resource")96 97 98class TraversableReader(TraversableResources, SimpleReader):99    """100    A TraversableResources based on SimpleReader. Resource providers101    may derive from this class to provide the TraversableResources102    interface by supplying the SimpleReader interface.103    """104 105    def files(self):106        return ResourceContainer(self)107