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170 lines
5.1 KiB
170 lines
5.1 KiB
"""
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Commonly useful validators.
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"""
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from __future__ import absolute_import, division, print_function
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from ._make import _AndValidator, and_, attrib, attrs
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__all__ = ["and_", "in_", "instance_of", "optional", "provides"]
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@attrs(repr=False, slots=True, hash=True)
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class _InstanceOfValidator(object):
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type = attrib()
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def __call__(self, inst, attr, value):
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"""
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We use a callable class to be able to change the ``__repr__``.
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"""
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if not isinstance(value, self.type):
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raise TypeError(
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"'{name}' must be {type!r} (got {value!r} that is a "
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"{actual!r}).".format(
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name=attr.name,
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type=self.type,
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actual=value.__class__,
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value=value,
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),
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attr,
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self.type,
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value,
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)
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def __repr__(self):
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return "<instance_of validator for type {type!r}>".format(
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type=self.type
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)
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def instance_of(type):
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"""
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A validator that raises a :exc:`TypeError` if the initializer is called
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with a wrong type for this particular attribute (checks are performed using
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:func:`isinstance` therefore it's also valid to pass a tuple of types).
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:param type: The type to check for.
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:type type: type or tuple of types
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:raises TypeError: With a human readable error message, the attribute
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(of type :class:`attr.Attribute`), the expected type, and the value it
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got.
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"""
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return _InstanceOfValidator(type)
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@attrs(repr=False, slots=True, hash=True)
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class _ProvidesValidator(object):
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interface = attrib()
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def __call__(self, inst, attr, value):
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"""
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We use a callable class to be able to change the ``__repr__``.
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"""
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if not self.interface.providedBy(value):
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raise TypeError(
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"'{name}' must provide {interface!r} which {value!r} "
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"doesn't.".format(
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name=attr.name, interface=self.interface, value=value
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),
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attr,
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self.interface,
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value,
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)
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def __repr__(self):
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return "<provides validator for interface {interface!r}>".format(
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interface=self.interface
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)
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def provides(interface):
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"""
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A validator that raises a :exc:`TypeError` if the initializer is called
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with an object that does not provide the requested *interface* (checks are
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performed using ``interface.providedBy(value)`` (see `zope.interface
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<https://zopeinterface.readthedocs.io/en/latest/>`_).
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:param zope.interface.Interface interface: The interface to check for.
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:raises TypeError: With a human readable error message, the attribute
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(of type :class:`attr.Attribute`), the expected interface, and the
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value it got.
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"""
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return _ProvidesValidator(interface)
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@attrs(repr=False, slots=True, hash=True)
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class _OptionalValidator(object):
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validator = attrib()
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def __call__(self, inst, attr, value):
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if value is None:
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return
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self.validator(inst, attr, value)
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def __repr__(self):
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return "<optional validator for {what} or None>".format(
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what=repr(self.validator)
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)
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def optional(validator):
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"""
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A validator that makes an attribute optional. An optional attribute is one
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which can be set to ``None`` in addition to satisfying the requirements of
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the sub-validator.
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:param validator: A validator (or a list of validators) that is used for
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non-``None`` values.
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:type validator: callable or :class:`list` of callables.
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.. versionadded:: 15.1.0
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.. versionchanged:: 17.1.0 *validator* can be a list of validators.
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"""
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if isinstance(validator, list):
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return _OptionalValidator(_AndValidator(validator))
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return _OptionalValidator(validator)
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@attrs(repr=False, slots=True, hash=True)
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class _InValidator(object):
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options = attrib()
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def __call__(self, inst, attr, value):
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try:
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in_options = value in self.options
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except TypeError as e: # e.g. `1 in "abc"`
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in_options = False
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if not in_options:
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raise ValueError(
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"'{name}' must be in {options!r} (got {value!r})".format(
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name=attr.name, options=self.options, value=value
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)
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)
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def __repr__(self):
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return "<in_ validator with options {options!r}>".format(
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options=self.options
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)
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def in_(options):
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"""
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A validator that raises a :exc:`ValueError` if the initializer is called
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with a value that does not belong in the options provided. The check is
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performed using ``value in options``.
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:param options: Allowed options.
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:type options: list, tuple, :class:`enum.Enum`, ...
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:raises ValueError: With a human readable error message, the attribute (of
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type :class:`attr.Attribute`), the expected options, and the value it
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got.
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.. versionadded:: 17.1.0
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"""
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return _InValidator(options)
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