Append Input values to suggester list

[prfraanje]

A few weeks ago I stumbled on textual while looking for a user interface framework for a dynamic control practical based on micropython. Textual turned out to be very suitable, fast and fun as well. Many thanks for developing! In my app there are two REPLs, one for python and one for micropython. I would love to add some history-search and autocompletion in the REPLs. I tried to append past input values to the list of suggestions, see this commented line and the following, but this did not work. The suggester._suggestions list was appended (verified in textual console), but past inputs were not recognised by the suggester. However, when I run a mini example by hand:

from textual.suggester import SuggestFromList
s = SuggestFromList([])
s._suggestions.append('a=1')
import asyncio
asyncio.run(s.get_suggestion('a'))

the suggestion was correctly given: 'a=1'. In my app I also played a bit with the LRUcache, but that did not help as well.
Please, can someone shed some light on this? And am I willing something (in)feasable?

[TomJGooding]

I suspect you may need to implement your own Suggester that doesn't use the cache, but I might be wrong.

Here's a quick example:

from textual import on
from textual.app import App, ComposeResult
from textual.suggester import Suggester
from textual.widgets import Input


class CustomSuggester(Suggester):
    def __init__(self, case_sensitive: bool = True) -> None:
        super().__init__(use_cache=False, case_sensitive=case_sensitive)
        self._suggestions: list[str] = []
        self._for_comparison: list[str] = []

    async def get_suggestion(self, value: str) -> str | None:
        for idx, suggestion in enumerate(self._for_comparison):
            if suggestion.startswith(value):
                return self._suggestions[idx]
        return None

    def add_suggestion(self, suggestion: str) -> None:
        if suggestion not in self._suggestions:
            self._suggestions.append(suggestion)
            self._for_comparison.append(
                suggestion if self.case_sensitive else suggestion.casefold()
            )


class ExampleApp(App):
    def compose(self) -> ComposeResult:
        yield Input(suggester=CustomSuggester())

    @on(Input.Submitted)
    def on_input_submitted(self, event: Input.Submitted) -> None:
        input = event.input
        assert isinstance(input.suggester, CustomSuggester)
        input.suggester.add_suggestion(event.value)
        input.clear()


if __name__ == "__main__":
    app = ExampleApp()
    app.run()

[prfraanje]

You're right, thanks for the inspiration! I adjusted a bit (using a deque with maxlen), to get the last match, and to scroll through the list of inputs using the arrow-up/down keys. Admitted, it's not perfect and very nice, and is not completely in line with the history-search-backward/forward of bash, but gives good behavior so far. Thanks!

from typing import TYPE_CHECKING, ClassVar, Iterable

from textual import on
from textual.app import App, ComposeResult
from textual.binding import Binding, BindingType
from textual.suggester import Suggester
from textual.widgets import Input

from collections import deque

class CustomSuggester(Suggester):
    def __init__(self, case_sensitive: bool = True) -> None:
        super().__init__(use_cache=False, case_sensitive=case_sensitive)
        self._suggestions: deque[str] = deque(maxlen=64)
        self._for_comparison: deque[str] = deque(maxlen=64)

    async def get_suggestion(self, value: str) -> str | None:
        for idx, suggestion in enumerate(self._for_comparison):
            if suggestion.startswith(value):
                return self._suggestions[idx]
        return None

    def add_suggestion(self, suggestion: str) -> None:
        #if suggestion not in self._suggestions:
        self._suggestions.appendleft(suggestion)
        self._for_comparison.appendleft(
            suggestion if self.case_sensitive else suggestion.casefold()
        )


class CustomInput(Input):
    BINDINGS: ClassVar[list[BindingType]] = Input.BINDINGS
    BINDINGS.extend([
        Binding("up", "cursor_up", "Backward input (but not suggestion)", show=False),
        Binding("down", "cursor_down", "Forward input (but not suggestion)", show=False),
    ])

    def __init__(self,*args,**kwargs) -> None:
        super().__init__(*args,**kwargs)
        self.backward_forward_index = None

    def action_cursor_right(self) -> None:
        """Accept an auto-completion or move the cursor one position to the right."""
        if self._cursor_at_end and self._suggestion:
            self.value = self._suggestion
            self.cursor_position = len(self.value)
        else:
            self.cursor_position += 1

    def action_cursor_up(self) -> None:
        """Backward in input list."""
        if self.backward_forward_index == None:
            self.backward_forward_index = 0
        else:
            self.backward_forward_index = (self.backward_forward_index+1) % len(self.suggester._suggestions)
        self.value = self.suggester._suggestions[self.backward_forward_index]

    def action_cursor_down(self) -> None:
        """Forward in input list."""
        if self.backward_forward_index == None:
            self.backward_forward_index = len(self.suggester._suggestions)-1
        else:
            self.backward_forward_index = (self.backward_forward_index-1) % len(self.suggester._suggestions)
        self.value = self.suggester._suggestions[self.backward_forward_index]


class ExampleApp(App):
    def compose(self) -> ComposeResult:
        yield CustomInput(suggester=CustomSuggester())

    @on(Input.Submitted)
    def on_input_submitted(self, event: Input.Submitted) -> None:
        input = event.input
        assert isinstance(input.suggester, CustomSuggester)
        input.suggester.add_suggestion(event.value)
        input.backward_forward_index = None
        input.clear()


if __name__ == "__main__":
    app = ExampleApp()
    app.run()