custom-vi-operator-and-text-object.py

#!/usr/bin/env python
"""
Example of adding a custom Vi operator and text object.
(Note that this API is not guaranteed to remain stable.)
"""
from prompt_toolkit import prompt
from prompt_toolkit.enums import EditingMode
from prompt_toolkit.key_binding import KeyBindings
from prompt_toolkit.key_binding.bindings.vi import (
    TextObject,
    create_operator_decorator,
    create_text_object_decorator,
)


def main():
    # We start with a `Registry` of default key bindings.
    bindings = KeyBindings()

    # Create the decorators to be used for registering text objects and
    # operators in this registry.
    operator = create_operator_decorator(bindings)
    text_object = create_text_object_decorator(bindings)

    # Create a custom operator.

    @operator("R")
    def _(event, text_object):
        "Custom operator that reverses text."
        buff = event.current_buffer

        # Get relative start/end coordinates.
        start, end = text_object.operator_range(buff.document)
        start += buff.cursor_position
        end += buff.cursor_position

        text = buff.text[start:end]
        text = "".join(reversed(text))

        event.app.current_buffer.text = buff.text[:start] + text + buff.text[end:]

    # Create a text object.

    @text_object("A")
    def _(event):
        "A custom text object that involves everything."
        # Note that a `TextObject` has coordinates, relative to the cursor position.
        buff = event.current_buffer
        return TextObject(
            -buff.document.cursor_position,  # The start.
            len(buff.text) - buff.document.cursor_position,
        )  # The end.

    # Read input.
    print('There is a custom text object "A" that applies to everything')
    print('and a custom operator "r" that reverses the text object.\n')

    print("Things that are possible:")
    print("-  Riw    - reverse inner word.")
    print("-  yA     - yank everything.")
    print("-  RA     - reverse everything.")

    text = prompt(
        "> ", default="hello world", key_bindings=bindings, editing_mode=EditingMode.VI
    )
    print("You said: %s" % text)


if __name__ == "__main__":
    main()