aboutsummaryrefslogtreecommitdiffstats
path: root/contrib/python/prompt-toolkit/py3/prompt_toolkit/validation.py
blob: 8bdffff524d14841c6b18b6ac90869c4116dcf44 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
"""
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)