Source code for ding.utils.loader.collection

from typing import Optional, List, Tuple, Callable, Any

from .base import ILoaderClass, Loader, CAPTURE_EXCEPTIONS
from .exception import CompositeStructureError
from .types import method

COLLECTION_ERROR_ITEM = Tuple[int, Exception]
COLLECTION_ERRORS = List[COLLECTION_ERROR_ITEM]


class CollectionError(CompositeStructureError):
    """
    Overview:
        Collection error.
    Interfaces:
        ``__init__``, ``errors``
    Properties:
        ``errors``
    """

    def __init__(self, errors: COLLECTION_ERRORS):
        """
        Overview:
            Initialize the CollectionError.
        Arguments:
            - errors (:obj:`COLLECTION_ERRORS`): The errors.
        """

        self.__errors = list(errors or [])
        CompositeStructureError.__init__(
            self, '{count} error(s) found in collection.'.format(count=repr(list(self.__errors)))
        )

    @property
    def errors(self) -> COLLECTION_ERRORS:
        """
        Overview:
            Get the errors.
        """

        return self.__errors


def collection(loader, type_back: bool = True) -> ILoaderClass:
    """
    Overview:
        Create a collection loader.
    Arguments:
        - loader (:obj:`ILoaderClass`): The loader.
        - type_back (:obj:`bool`): Whether to convert the type back.
    """

    loader = Loader(loader)

    def _load(value):
        _result = []
        _errors = []

        for index, item in enumerate(value):
            try:
                _return = loader.load(item)
            except CAPTURE_EXCEPTIONS as err:
                _errors.append((index, err))
            else:
                _result.append(_return)

        if _errors:
            raise CollectionError(_errors)

        if type_back:
            _result = type(value)(_result)
        return _result

    return method('__iter__') & Loader(_load)


def tuple_(*loaders) -> ILoaderClass:
    """
    Overview:
        Create a tuple loader.
    Arguments:
        - loaders (:obj:`tuple`): The loaders.
    """

    loaders = [Loader(loader) for loader in loaders]

    def _load(value: tuple):
        return tuple([loader(item) for loader, item in zip(loaders, value)])

    return tuple & length_is(len(loaders)) & Loader(_load)


def length(min_length: Optional[int] = None, max_length: Optional[int] = None) -> ILoaderClass:
    """
    Overview:
        Create a length loader.
    Arguments:
        - min_length (:obj:`int`): The minimum length.
        - max_length (:obj:`int`): The maximum length.
    """

    def _load(value):
        _length = len(value)
        if min_length is not None and _length < min_length:
            raise ValueError(
                'minimum length is {expect}, but {actual} found'.format(expect=repr(min_length), actual=repr(_length))
            )
        if max_length is not None and _length > max_length:
            raise ValueError(
                'maximum length is {expect}, but {actual} found'.format(expect=repr(max_length), actual=repr(_length))
            )

        return value

    return method('__len__') & Loader(_load)


def length_is(length_: int) -> ILoaderClass:
    """
    Overview:
        Create a length loader.
    Arguments:
        - length_ (:obj:`int`): The length.
    """

    return length(min_length=length_, max_length=length_)


def contains(content) -> ILoaderClass:
    """
    Overview:
        Create a contains loader.
    Arguments:
        - content (:obj:`Any`): The content.
    """

    def _load(value):
        if content not in value:
            raise ValueError('{content} not found in value'.format(content=repr(content)))

        return value

    return method('__contains__') & Loader(_load)


def cofilter(checker: Callable[[Any], bool], type_back: bool = True) -> ILoaderClass:
    """
    Overview:
        Create a cofilter loader.
    Arguments:
        - checker (:obj:`Callable[[Any], bool]`): The checker.
        - type_back (:obj:`bool`): Whether to convert the type back.
    """

    def _load(value):
        _result = [item for item in value if checker(item)]
        if type_back:
            _result = type(value)(_result)
        return _result

    return method('__iter__') & Loader(_load)


def tpselector(*indices) -> ILoaderClass:
    """
    Overview:
        Create a tuple selector loader.
    Arguments:
        - indices (:obj:`tuple`): The indices.
    """

    def _load(value: tuple):
        return tuple([value[index] for index in indices])

    return tuple & Loader(_load)