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ORPA-pyOpenRPA/WPy32-3720/python-3.7.2/Lib/site-packages/prompt_toolkit/validation.py

189 lines
5.7 KiB

6 years ago
"""
Input validation for a `Buffer`.
(Validators will be called before accepting input.)
"""
from __future__ import unicode_literals
from .filters import to_filter
from .eventloop import Future, run_in_executor
from abc import ABCMeta, abstractmethod
from six import with_metaclass, text_type
__all__ = [
'ConditionalValidator',
'ValidationError',
'Validator',
'ThreadedValidator',
'DummyValidator',
'DynamicValidator',
]
class ValidationError(Exception):
"""
Error raised by :meth:`.Validator.validate`.
:param cursor_position: The cursor position where the error occurred.
: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.
A validator is typically created in one of the following two ways:
- Either by overriding this class and implementing the `validate` method.
- Or by passing a callable to `Validator.from_callable`.
If the validation takes some time and needs to happen in a background
thread, this can be wrapped in a :class:`.ThreadedValidator`.
"""
@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
def get_validate_future(self, document):
"""
Return a `Future` which is set when the validation is ready.
This function can be overloaded in order to provide an asynchronous
implementation.
"""
try:
self.validate(document)
except ValidationError as e:
return Future.fail(e)
else:
return Future.succeed(None)
@classmethod
def from_callable(cls, validate_func, error_message='Invalid input',
move_cursor_to_end=False):
"""
Create a validator from a simple validate callable. E.g.:
.. code:: python
def is_valid(text):
return text in ['hello', 'world']
Validator.from_callable(is_valid, error_message='Invalid input')
:param validate_func: Callable that takes the input string, and returns
`True` if the input is valid input.
:param error_message: Message to be displayed if the input is invalid.
:param move_cursor_to_end: Move the cursor to the end of the input, if
the input is invalid.
"""
return _ValidatorFromCallable(
validate_func, error_message, move_cursor_to_end)
class _ValidatorFromCallable(Validator):
"""
Validate input from a simple callable.
"""
def __init__(self, func, error_message, move_cursor_to_end):
assert callable(func)
assert isinstance(error_message, text_type)
self.func = func
self.error_message = error_message
self.move_cursor_to_end = move_cursor_to_end
def __repr__(self):
return 'Validator.from_callable(%r)' % (self.func, )
def validate(self, document):
if not self.func(document.text):
if self.move_cursor_to_end:
index = len(document.text)
else:
index = 0
raise ValidationError(cursor_position=index,
message=self.error_message)
class ThreadedValidator(Validator):
"""
Wrapper that runs input validation in a thread.
(Use this to prevent the user interface from becoming unresponsive if the
input validation takes too much time.)
"""
def __init__(self, validator):
assert isinstance(validator, Validator)
self.validator = validator
def validate(self, document):
return self.validator.validate(document)
def get_validate_future(self, document):
"""
Run the `validate` function in a thread.
"""
def run_validation_thread():
return self.validate(document)
f = run_in_executor(run_validation_thread)
return f
class DummyValidator(Validator):
"""
Validator class that accepts any input.
"""
def validate(self, document):
pass # Don't raise any exception.
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_filter(filter)
def validate(self, document):
# Call the validator only if the filter is active.
if self.filter():
self.validator.validate(document)
class DynamicValidator(Validator):
"""
Validator class that can dynamically returns any Validator.
:param get_validator: Callable that returns a :class:`.Validator` instance.
"""
def __init__(self, get_validator):
assert callable(get_validator)
self.get_validator = get_validator
def validate(self, document):
validator = self.get_validator() or DummyValidator()
assert isinstance(validator, Validator)
return validator.validate(document)
def get_validate_future(self, document):
validator = self.get_validator() or DummyValidator()
assert isinstance(validator, Validator)
return validator.get_validate_future(document)