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# SPDX-License-Identifier: MIT
"""
Commonly useful validators.
"""
import operator
import re
from contextlib import contextmanager
from re import Pattern
from ._config import get_run_validators, set_run_validators
from ._make import _AndValidator, and_, attrib, attrs
from .converters import default_if_none
from .exceptions import NotCallableError
__all__ = [
"and_",
"deep_iterable",
"deep_mapping",
"disabled",
"ge",
"get_disabled",
"gt",
"in_",
"instance_of",
"is_callable",
"le",
"lt",
"matches_re",
"max_len",
"min_len",
"not_",
"optional",
"provides",
"set_disabled",
]
def set_disabled(disabled):
"""
Globally disable or enable running validators.
By default, they are run.
:param disabled: If ``True``, disable running all validators.
:type disabled: bool
.. warning::
This function is not thread-safe!
.. versionadded:: 21.3.0
"""
set_run_validators(not disabled)
def get_disabled():
"""
Return a bool indicating whether validators are currently disabled or not.
:return: ``True`` if validators are currently disabled.
:rtype: bool
.. versionadded:: 21.3.0
"""
return not get_run_validators()
@contextmanager
def disabled():
"""
Context manager that disables running validators within its context.
.. warning::
This context manager is not thread-safe!
.. versionadded:: 21.3.0
"""
set_run_validators(False)
try:
yield
finally:
set_run_validators(True)
@attrs(repr=False, slots=True, hash=True)
class _InstanceOfValidator:
type = attrib()
def __call__(self, inst, attr, value):
"""
We use a callable class to be able to change the ``__repr__``.
"""
if not isinstance(value, self.type):
msg = "'{name}' must be {type!r} (got {value!r} that is a {actual!r}).".format(
name=attr.name,
type=self.type,
actual=value.__class__,
value=value,
)
raise TypeError(
msg,
attr,
self.type,
value,
)
def __repr__(self):
return f"<instance_of validator for type {self.type!r}>"
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 type
:raises TypeError: With a human readable error message, the attribute
(of type `attrs.Attribute`), the expected type, and the value it
got.
"""
return _InstanceOfValidator(type)
@attrs(repr=False, frozen=True, slots=True)
class _MatchesReValidator:
pattern = attrib()
match_func = attrib()
def __call__(self, inst, attr, value):
"""
We use a callable class to be able to change the ``__repr__``.
"""
if not self.match_func(value):
msg = "'{name}' must match regex {pattern!r} ({value!r} doesn't)".format(
name=attr.name, pattern=self.pattern.pattern, value=value
)
raise ValueError(
msg,
attr,
self.pattern,
value,
)
def __repr__(self):
return f"<matches_re validator for pattern {self.pattern!r}>"
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 regex: a regex string or precompiled pattern 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. Valid options
are `re.fullmatch`, `re.search`, and `re.match`; the default ``None``
means `re.fullmatch`. For performance reasons, the pattern is always
precompiled using `re.compile`.
.. versionadded:: 19.2.0
.. versionchanged:: 21.3.0 *regex* can be a pre-compiled pattern.
"""
valid_funcs = (re.fullmatch, None, re.search, re.match)
if func not in valid_funcs:
msg = "'func' must be one of {}.".format(
", ".join(
sorted(e and e.__name__ or "None" for e in set(valid_funcs))
)
)
raise ValueError(msg)
if isinstance(regex, Pattern):
if flags:
msg = "'flags' can only be used with a string pattern; pass flags to re.compile() instead"
raise TypeError(msg)
pattern = regex
else:
pattern = re.compile(regex, flags)
if func is re.match:
match_func = pattern.match
elif func is re.search:
match_func = pattern.search
else:
match_func = pattern.fullmatch
return _MatchesReValidator(pattern, match_func)
@attrs(repr=False, slots=True, hash=True)
class _ProvidesValidator:
interface = attrib()
def __call__(self, inst, attr, value):
"""
We use a callable class to be able to change the ``__repr__``.
"""
if not self.interface.providedBy(value):
msg = "'{name}' must provide {interface!r} which {value!r} doesn't.".format(
name=attr.name, interface=self.interface, value=value
)
raise TypeError(
msg,
attr,
self.interface,
value,
)
def __repr__(self):
return f"<provides validator for interface {self.interface!r}>"
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 `attrs.Attribute`), the expected interface, and the
value it got.
.. deprecated:: 23.1.0
"""
import warnings
warnings.warn(
"attrs's zope-interface support is deprecated and will be removed in, "
"or after, April 2024.",
DeprecationWarning,
stacklevel=2,
)
return _ProvidesValidator(interface)
@attrs(repr=False, slots=True, hash=True)
class _OptionalValidator:
validator = attrib()
def __call__(self, inst, attr, value):
if value is None:
return
self.validator(inst, attr, value)
def __repr__(self):
return f"<optional validator for {self.validator!r} or None>"
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 Callable | tuple[Callable] | list[Callable] validator: A validator
(or validators) that is used for non-``None`` values.
.. versionadded:: 15.1.0
.. versionchanged:: 17.1.0 *validator* can be a list of validators.
.. versionchanged:: 23.1.0 *validator* can also be a tuple of validators.
"""
if isinstance(validator, (list, tuple)):
return _OptionalValidator(_AndValidator(validator))
return _OptionalValidator(validator)
@attrs(repr=False, slots=True, hash=True)
class _InValidator:
options = attrib()
def __call__(self, inst, attr, value):
try:
in_options = value in self.options
except TypeError: # e.g. `1 in "abc"`
in_options = False
if not in_options:
msg = f"'{attr.name}' must be in {self.options!r} (got {value!r})"
raise ValueError(
msg,
attr,
self.options,
value,
)
def __repr__(self):
return f"<in_ validator with options {self.options!r}>"
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 `attrs.Attribute`), the expected options, and the value it
got.
.. versionadded:: 17.1.0
.. versionchanged:: 22.1.0
The ValueError was incomplete until now and only contained the human
readable error message. Now it contains all the information that has
been promised since 17.1.0.
"""
return _InValidator(options)
@attrs(repr=False, slots=False, hash=True)
class _IsCallableValidator:
def __call__(self, inst, attr, value):
"""
We use a callable class to be able to change the ``__repr__``.
"""
if not callable(value):
message = (
"'{name}' must be callable "
"(got {value!r} that is a {actual!r})."
)
raise NotCallableError(
msg=message.format(
name=attr.name, value=value, actual=value.__class__
),
value=value,
)
def __repr__(self):
return "<is_callable validator>"
def is_callable():
"""
A validator that raises a `attrs.exceptions.NotCallableError` if the
initializer is called with a value for this particular attribute
that is not callable.
.. versionadded:: 19.1.0
:raises attrs.exceptions.NotCallableError: With a human readable error
message containing the attribute (`attrs.Attribute`) name,
and the value it got.
"""
return _IsCallableValidator()
@attrs(repr=False, slots=True, hash=True)
class _DeepIterable:
member_validator = attrib(validator=is_callable())
iterable_validator = attrib(
default=None, validator=optional(is_callable())
)
def __call__(self, inst, attr, value):
"""
We use a callable class to be able to change the ``__repr__``.
"""
if self.iterable_validator is not None:
self.iterable_validator(inst, attr, value)
for member in value:
self.member_validator(inst, attr, member)
def __repr__(self):
iterable_identifier = (
""
if self.iterable_validator is None
else f" {self.iterable_validator!r}"
)
return (
f"<deep_iterable validator for{iterable_identifier}"
f" iterables of {self.member_validator!r}>"
)
def deep_iterable(member_validator, iterable_validator=None):
"""
A validator that performs deep validation of an iterable.
:param member_validator: Validator(s) 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
"""
if isinstance(member_validator, (list, tuple)):
member_validator = and_(*member_validator)
return _DeepIterable(member_validator, iterable_validator)
@attrs(repr=False, slots=True, hash=True)
class _DeepMapping:
key_validator = attrib(validator=is_callable())
value_validator = attrib(validator=is_callable())
mapping_validator = attrib(default=None, validator=optional(is_callable()))
def __call__(self, inst, attr, value):
"""
We use a callable class to be able to change the ``__repr__``.
"""
if self.mapping_validator is not None:
self.mapping_validator(inst, attr, value)
for key in value:
self.key_validator(inst, attr, key)
self.value_validator(inst, attr, value[key])
def __repr__(self):
return (
"<deep_mapping validator for objects mapping {key!r} to {value!r}>"
).format(key=self.key_validator, value=self.value_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)
@attrs(repr=False, frozen=True, slots=True)
class _NumberValidator:
bound = attrib()
compare_op = attrib()
compare_func = attrib()
def __call__(self, inst, attr, value):
"""
We use a callable class to be able to change the ``__repr__``.
"""
if not self.compare_func(value, self.bound):
msg = f"'{attr.name}' must be {self.compare_op} {self.bound}: {value}"
raise ValueError(msg)
def __repr__(self):
return f"<Validator for x {self.compare_op} {self.bound}>"
def lt(val):
"""
A validator that raises `ValueError` if the initializer is called
with a number larger or equal to *val*.
:param val: Exclusive upper bound for values
.. versionadded:: 21.3.0
"""
return _NumberValidator(val, "<", operator.lt)
def le(val):
"""
A validator that raises `ValueError` if the initializer is called
with a number greater than *val*.
:param val: Inclusive upper bound for values
.. versionadded:: 21.3.0
"""
return _NumberValidator(val, "<=", operator.le)
def ge(val):
"""
A validator that raises `ValueError` if the initializer is called
with a number smaller than *val*.
:param val: Inclusive lower bound for values
.. versionadded:: 21.3.0
"""
return _NumberValidator(val, ">=", operator.ge)
def gt(val):
"""
A validator that raises `ValueError` if the initializer is called
with a number smaller or equal to *val*.
:param val: Exclusive lower bound for values
.. versionadded:: 21.3.0
"""
return _NumberValidator(val, ">", operator.gt)
@attrs(repr=False, frozen=True, slots=True)
class _MaxLengthValidator:
max_length = attrib()
def __call__(self, inst, attr, value):
"""
We use a callable class to be able to change the ``__repr__``.
"""
if len(value) > self.max_length:
msg = f"Length of '{attr.name}' must be <= {self.max_length}: {len(value)}"
raise ValueError(msg)
def __repr__(self):
return f"<max_len validator for {self.max_length}>"
def max_len(length):
"""
A validator that raises `ValueError` if the initializer is called
with a string or iterable that is longer than *length*.
:param int length: Maximum length of the string or iterable
.. versionadded:: 21.3.0
"""
return _MaxLengthValidator(length)
@attrs(repr=False, frozen=True, slots=True)
class _MinLengthValidator:
min_length = attrib()
def __call__(self, inst, attr, value):
"""
We use a callable class to be able to change the ``__repr__``.
"""
if len(value) < self.min_length:
msg = f"Length of '{attr.name}' must be >= {self.min_length}: {len(value)}"
raise ValueError(msg)
def __repr__(self):
return f"<min_len validator for {self.min_length}>"
def min_len(length):
"""
A validator that raises `ValueError` if the initializer is called
with a string or iterable that is shorter than *length*.
:param int length: Minimum length of the string or iterable
.. versionadded:: 22.1.0
"""
return _MinLengthValidator(length)
@attrs(repr=False, slots=True, hash=True)
class _SubclassOfValidator:
type = attrib()
def __call__(self, inst, attr, value):
"""
We use a callable class to be able to change the ``__repr__``.
"""
if not issubclass(value, self.type):
msg = f"'{attr.name}' must be a subclass of {self.type!r} (got {value!r})."
raise TypeError(
msg,
attr,
self.type,
value,
)
def __repr__(self):
return f"<subclass_of validator for type {self.type!r}>"
def _subclass_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
`issubclass` 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 `attrs.Attribute`), the expected type, and the value it
got.
"""
return _SubclassOfValidator(type)
@attrs(repr=False, slots=True, hash=True)
class _NotValidator:
validator = attrib()
msg = attrib(
converter=default_if_none(
"not_ validator child '{validator!r}' "
"did not raise a captured error"
)
)
exc_types = attrib(
validator=deep_iterable(
member_validator=_subclass_of(Exception),
iterable_validator=instance_of(tuple),
),
)
def __call__(self, inst, attr, value):
try:
self.validator(inst, attr, value)
except self.exc_types:
pass # suppress error to invert validity
else:
raise ValueError(
self.msg.format(
validator=self.validator,
exc_types=self.exc_types,
),
attr,
self.validator,
value,
self.exc_types,
)
def __repr__(self):
return (
"<not_ validator wrapping {what!r}, capturing {exc_types!r}>"
).format(
what=self.validator,
exc_types=self.exc_types,
)
def not_(validator, *, msg=None, exc_types=(ValueError, TypeError)):
"""
A validator that wraps and logically 'inverts' the validator passed to it.
It will raise a `ValueError` if the provided validator *doesn't* raise a
`ValueError` or `TypeError` (by default), and will suppress the exception
if the provided validator *does*.
Intended to be used with existing validators to compose logic without
needing to create inverted variants, for example, ``not_(in_(...))``.
:param validator: A validator to be logically inverted.
:param msg: Message to raise if validator fails.
Formatted with keys ``exc_types`` and ``validator``.
:type msg: str
:param exc_types: Exception type(s) to capture.
Other types raised by child validators will not be intercepted and
pass through.
:raises ValueError: With a human readable error message,
the attribute (of type `attrs.Attribute`),
the validator that failed to raise an exception,
the value it got,
and the expected exception types.
.. versionadded:: 22.2.0
"""
try:
exc_types = tuple(exc_types)
except TypeError:
exc_types = (exc_types,)
return _NotValidator(validator, msg, exc_types)