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"""
Input validation for a `Buffer`.
(Validators will be called before accepting input.)
"""
from abc import ABCMeta, abstractmethod
from typing import Callable, Optional
from prompt_toolkit.eventloop import run_in_executor_with_context
from .document import Document
from .filters import FilterOrBool, to_filter
__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: int = 0, message: str = "") -> None:
super().__init__(message)
self.cursor_position = cursor_position
self.message = message
def __repr__(self) -> str:
return "{}(cursor_position={!r}, message={!r})".format(
self.__class__.__name__,
self.cursor_position,
self.message,
)
class Validator(metaclass=ABCMeta):
"""
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: Document) -> None:
"""
Validate the input.
If invalid, this should raise a :class:`.ValidationError`.
:param document: :class:`~prompt_toolkit.document.Document` instance.
"""
pass
async def validate_async(self, document: Document) -> None:
"""
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:
raise
@classmethod
def from_callable(
cls,
validate_func: Callable[[str], bool],
error_message: str = "Invalid input",
move_cursor_to_end: bool = False,
) -> "Validator":
"""
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: Callable[[str], bool], error_message: str, move_cursor_to_end: bool
) -> None:
self.func = func
self.error_message = error_message
self.move_cursor_to_end = move_cursor_to_end
def __repr__(self) -> str:
return f"Validator.from_callable({self.func!r})"
def validate(self, document: Document) -> None:
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: Validator) -> None:
self.validator = validator
def validate(self, document: Document) -> None:
self.validator.validate(document)
async def validate_async(self, document: Document) -> None:
"""
Run the `validate` function in a thread.
"""
def run_validation_thread() -> None:
return self.validate(document)
await run_in_executor_with_context(run_validation_thread)
class DummyValidator(Validator):
"""
Validator class that accepts any input.
"""
def validate(self, document: Document) -> None:
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: Validator, filter: FilterOrBool) -> None:
self.validator = validator
self.filter = to_filter(filter)
def validate(self, document: Document) -> None:
# 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: Callable[[], Optional[Validator]]) -> None:
self.get_validator = get_validator
def validate(self, document: Document) -> None:
validator = self.get_validator() or DummyValidator()
validator.validate(document)
async def validate_async(self, document: Document) -> None:
validator = self.get_validator() or DummyValidator()
await validator.validate_async(document)
|
