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"""
Input validation for a `Buffer`.
(Validators will be called before accepting input.)
"""
from __future__ import unicode_literals
from .filters import to_simple_filter
from abc import ABCMeta, abstractmethod
from six import with_metaclass
__all__ = (
'ConditionalValidator',
'ValidationError',
'Validator',
)
class ValidationError(Exception):
"""
Error raised by :meth:`.Validator.validate`.
:param cursor_position: The cursor position where the error occured.
:param message: Text.
"""
def __init__(self, cursor_position=0, message=''):
super(ValidationError, self).__init__(message)
self.cursor_position = cursor_position
self.message = message
def __repr__(self):
return '%s(cursor_position=%r, message=%r)' % (
self.__class__.__name__, self.cursor_position, self.message)
class Validator(with_metaclass(ABCMeta, object)):
"""
Abstract base class for an input validator.
"""
@abstractmethod
def validate(self, document):
"""
Validate the input.
If invalid, this should raise a :class:`.ValidationError`.
:param document: :class:`~prompt_toolkit.document.Document` instance.
"""
pass
class ConditionalValidator(Validator):
"""
Validator that can be switched on/off according to
a filter. (This wraps around another validator.)
"""
def __init__(self, validator, filter):
assert isinstance(validator, Validator)
self.validator = validator
self.filter = to_simple_filter(filter)
def validate(self, document):
# Call the validator only if the filter is active.
if self.filter():
self.validator.validate(document)
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