validators

def and_(*validators):
    """
    A validator that composes multiple validators into one.

    When called on a value, it runs all wrapped validators.

    :param callables validators: Arbitrary number of validators.

    .. versionadded:: 17.1.0
    """
    vals = []
    for validator in validators:
        vals.extend(
            validator._validators
            if isinstance(validator, _AndValidator)
            else [validator]
        )

    return _AndValidator(tuple(vals))

def deep_iterable(member_validator, iterable_validator=None):
    """
    A validator that performs deep validation of an iterable.

    :param member_validator: Validator to apply to iterable members
    :param iterable_validator: Validator to apply to iterable itself
        (optional)

    .. versionadded:: 19.1.0

    :raises TypeError: if any sub-validators fail
    """
    return _DeepIterable(member_validator, iterable_validator)

def deep_mapping(key_validator, value_validator, mapping_validator=None):
    """
    A validator that performs deep validation of a dictionary.

    :param key_validator: Validator to apply to dictionary keys
    :param value_validator: Validator to apply to dictionary values
    :param mapping_validator: Validator to apply to top-level mapping
        attribute (optional)

    .. versionadded:: 19.1.0

    :raises TypeError: if any sub-validators fail
    """
    return _DeepMapping(key_validator, value_validator, mapping_validator)

def in_(options):
    """
    A validator that raises a `ValueError` if the initializer is called
    with a value that does not belong in the options provided.  The check is
    performed using ``value in options``.

    :param options: Allowed options.
    :type options: list, tuple, `enum.Enum`, ...

    :raises ValueError: With a human readable error message, the attribute (of
       type `attr.Attribute`), the expected options, and the value it
       got.

    .. versionadded:: 17.1.0
    """
    return _InValidator(options)

def instance_of(type):
    """
    A validator that raises a `TypeError` if the initializer is called
    with a wrong type for this particular attribute (checks are performed using
    `isinstance` therefore it's also valid to pass a tuple of types).

    :param type: The type to check for.
    :type type: type or tuple of types

    :raises TypeError: With a human readable error message, the attribute
        (of type `attr.Attribute`), the expected type, and the value it
        got.
    """
    return _InstanceOfValidator(type)

def is_callable():
    """
    A validator that raises a `attr.exceptions.NotCallableError` if the
    initializer is called with a value for this particular attribute
    that is not callable.

    .. versionadded:: 19.1.0

    :raises `attr.exceptions.NotCallableError`: With a human readable error
        message containing the attribute (`attr.Attribute`) name,
        and the value it got.
    """
    return _IsCallableValidator()

def matches_re(regex, flags=0, func=None):
    r"""
    A validator that raises `ValueError` if the initializer is called
    with a string that doesn't match *regex*.

    :param str regex: a regex string to match against
    :param int flags: flags that will be passed to the underlying re function
        (default 0)
    :param callable func: which underlying `re` function to call (options
        are `re.fullmatch`, `re.search`, `re.match`, default
        is ``None`` which means either `re.fullmatch` or an emulation of
        it on Python 2). For performance reasons, they won't be used directly
        but on a pre-`re.compile`\ ed pattern.

    .. versionadded:: 19.2.0
    """
    fullmatch = getattr(re, "fullmatch", None)
    valid_funcs = (fullmatch, None, re.search, re.match)
    if func not in valid_funcs:
        raise ValueError(
            "'func' must be one of %s."
            % (
                ", ".join(
                    sorted(
                        e and e.__name__ or "None" for e in set(valid_funcs)
                    )
                ),
            )
        )

    pattern = re.compile(regex, flags)
    if func is re.match:
        match_func = pattern.match
    elif func is re.search:
        match_func = pattern.search
    else:
        if fullmatch:
            match_func = pattern.fullmatch
        else:
            pattern = re.compile(r"(?:{})\Z".format(regex), flags)
            match_func = pattern.match

    return _MatchesReValidator(pattern, flags, match_func)

def optional(validator):
    """
    A validator that makes an attribute optional.  An optional attribute is one
    which can be set to ``None`` in addition to satisfying the requirements of
    the sub-validator.

    :param validator: A validator (or a list of validators) that is used for
        non-``None`` values.
    :type validator: callable or `list` of callables.

    .. versionadded:: 15.1.0
    .. versionchanged:: 17.1.0 *validator* can be a list of validators.
    """
    if isinstance(validator, list):
        return _OptionalValidator(_AndValidator(validator))
    return _OptionalValidator(validator)

def provides(interface):
    """
    A validator that raises a `TypeError` if the initializer is called
    with an object that does not provide the requested *interface* (checks are
    performed using ``interface.providedBy(value)`` (see `zope.interface
    <https://zopeinterface.readthedocs.io/en/latest/>`_).

    :param interface: The interface to check for.
    :type interface: ``zope.interface.Interface``

    :raises TypeError: With a human readable error message, the attribute
        (of type `attr.Attribute`), the expected interface, and the
        value it got.
    """
    return _ProvidesValidator(interface)