Merge pull request #5403 from Textualize/select-experiment

`Select.type_to_search`

Author: willmcgugan

CHANGELOG.md

@@ -7,14 +7,14 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## Unreleased
 
-
 ### Fixed
 
 - Fixed `Pilot.click` not working with `times` parameter https://github.com/Textualize/textual/pull/5398
 
 ### Added
 
 - Added `from_app_focus` to `Focus` event to indicate if a widget is being focused because the app itself has regained focus or not https://github.com/Textualize/textual/pull/5379
+- - Added `Select.type_to_search` which allows you to type to move the cursor to a matching option https://github.com/Textualize/textual/pull/5403
 
 ### Changed
 

docs/widgets/select.md

@@ -88,13 +88,15 @@ The following example presents a `Select` created using the `from_values` class
 
 ## Blank state
 
-The widget `Select` has an option `allow_blank` for its constructor.
+The `Select` widget has an option `allow_blank` for its constructor.
 If set to `True`, the widget may be in a state where there is no selection, in which case its value will be the special constant [`Select.BLANK`][textual.widgets.Select.BLANK].
 The auxiliary methods [`Select.is_blank`][textual.widgets.Select.is_blank] and [`Select.clear`][textual.widgets.Select.clear] provide a convenient way to check if the widget is in this state and to set this state, respectively.
 
+## Type to search
 
-## Reactive Attributes
+The `Select` widget has a `type_to_search` attribute which allows you to type to move the cursor to a matching option when the widget is expanded. To disable this behavior, set the attribute to `False`.
 
+## Reactive Attributes
 
 | Name       | Type                           | Default                                        | Description                         |
 |------------|--------------------------------|------------------------------------------------|-------------------------------------|

src/textual/widgets/_select.py

@@ -13,6 +13,7 @@
 from textual.css.query import NoMatches
 from textual.message import Message
 from textual.reactive import var
+from textual.timer import Timer
 from textual.widgets import Static
 from textual.widgets._option_list import Option, OptionList
 
@@ -59,6 +60,57 @@ class UpdateSelection(Message):
         option_index: int
         """The index of the new selection."""
 
+    def __init__(self, type_to_search: bool = True) -> None:
+        super().__init__()
+        self._type_to_search = type_to_search
+        """If True (default), the user can type to search for a matching option and the cursor will jump to it."""
+
+        self._search_query: str = ""
+        """The current search query used to find a matching option and jump to it."""
+
+        self._search_reset_delay: float = 0.7
+        """The number of seconds to wait after the most recent key press before resetting the search query."""
+
+    def on_mount(self) -> None:
+        def reset_query() -> None:
+            self._search_query = ""
+
+        self._search_reset_timer = Timer(
+            self, self._search_reset_delay, callback=reset_query
+        )
+
+    def watch_has_focus(self, value: bool) -> None:
+        self._search_query = ""
+        if value:
+            self._search_reset_timer._start()
+        else:
+            self._search_reset_timer.reset()
+            self._search_reset_timer.stop()
+        super().watch_has_focus(value)
+
+    async def _on_key(self, event: events.Key) -> None:
+        if not self._type_to_search:
+            return
+
+        self._search_reset_timer.reset()
+
+        if event.character is not None and event.is_printable:
+            event.time = 0
+            event.stop()
+            event.prevent_default()
+
+            # Update the search query and jump to the next option that matches.
+            self._search_query += event.character
+            index = self._find_search_match(self._search_query)
+            if index is not None:
+                self.select(index)
+
+    def check_consume_key(self, key: str, character: str | None = None) -> bool:
+        """Check if the widget may consume the given key."""
+        return (
+            self._type_to_search and character is not None and character.isprintable()
+        )
+
     def select(self, index: int | None) -> None:
         """Move selection.
 
@@ -68,6 +120,38 @@ def select(self, index: int | None) -> None:
         self.highlighted = index
         self.scroll_to_highlight()
 
+    def _find_search_match(self, query: str) -> int | None:
+        """A simple substring search which favors options containing the substring
+        earlier in the prompt.
+
+        Args:
+            query: The substring to search for.
+
+        Returns:
+            The index of the option that matches the query, or `None` if no match is found.
+        """
+        best_match: int | None = None
+        minimum_index: int | None = None
+
+        query = query.lower()
+        for index, option in enumerate(self._options):
+            prompt = option.prompt
+            if isinstance(prompt, Text):
+                lower_prompt = prompt.plain.lower()
+            elif isinstance(prompt, str):
+                lower_prompt = prompt.lower()
+            else:
+                continue
+
+            match_index = lower_prompt.find(query)
+            if match_index != -1 and (
+                minimum_index is None or match_index < minimum_index
+            ):
+                best_match = index
+                minimum_index = match_index
+
+        return best_match
+
     def action_dismiss(self) -> None:
         """Dismiss the overlay."""
         self.post_message(self.Dismiss())
@@ -295,6 +379,7 @@ def __init__(
         prompt: str = "Select",
         allow_blank: bool = True,
         value: SelectType | NoSelection = BLANK,
+        type_to_search: bool = True,
         name: str | None = None,
         id: str | None = None,
         classes: str | None = None,
@@ -313,6 +398,7 @@ def __init__(
             value: Initial value selected. Should be one of the values in `options`.
                 If no initial value is set and `allow_blank` is `False`, the widget
                 will auto-select the first available option.
+            type_to_search: If `True`, typing will search for options.
             name: The name of the select control.
             id: The ID of the control in the DOM.
             classes: The CSS classes of the control.
@@ -327,6 +413,7 @@ def __init__(
         self.prompt = prompt
         self._value = value
         self._setup_variables_for_options(options)
+        self._type_to_search = type_to_search
         if tooltip is not None:
             self.tooltip = tooltip
 
@@ -338,6 +425,7 @@ def from_values(
         prompt: str = "Select",
         allow_blank: bool = True,
         value: SelectType | NoSelection = BLANK,
+        type_to_search: bool = True,
         name: str | None = None,
         id: str | None = None,
         classes: str | None = None,
@@ -357,6 +445,7 @@ def from_values(
             value: Initial value selected. Should be one of the values in `values`.
                 If no initial value is set and `allow_blank` is `False`, the widget
                 will auto-select the first available value.
+            type_to_search: If `True`, typing will search for options.
             name: The name of the select control.
             id: The ID of the control in the DOM.
             classes: The CSS classes of the control.
@@ -372,6 +461,7 @@ def from_values(
             prompt=prompt,
             allow_blank=allow_blank,
             value=value,
+            type_to_search=type_to_search,
             name=name,
             id=id,
             classes=classes,
@@ -496,7 +586,7 @@ def _watch_value(self, value: SelectType | NoSelection) -> None:
     def compose(self) -> ComposeResult:
         """Compose Select with overlay and current value."""
         yield SelectCurrent(self.prompt)
-        yield SelectOverlay()
+        yield SelectOverlay(type_to_search=self._type_to_search)
 
     def _on_mount(self, _event: events.Mount) -> None:
         """Set initial values."""