use std::sync::Arc; use gpui::{App, Entity, FocusHandle, Focusable, prelude::*};use ui::prelude::*;use ui_input::{ErasedEditor, ErasedEditorEvent}; /// The head of a [`Picker`](crate::Picker).pub(crate) enum Head {    /// Picker has an editor that allows the user to filter the list.    Editor(Arc<dyn ErasedEditor>),     /// Picker has no head, it's just a list of items.    Empty(Entity<EmptyHead>),} impl Head {    pub fn editor<V: 'static>(        placeholder_text: Arc<str>,        mut edit_handler: impl FnMut(&mut V, &ErasedEditorEvent, &mut Window, &mut Context<V>) + 'static,        window: &mut Window,        cx: &mut Context<V>,    ) -> Self {        let editor = (ui_input::ERASED_EDITOR_FACTORY.get().unwrap())(window, cx);         editor.set_placeholder_text(placeholder_text.as_ref(), window, cx);        let this = cx.weak_entity();        editor            .subscribe(                Box::new(move |event, window, cx| {                    this.update(cx, |this, cx| (edit_handler)(this, &event, window, cx))                        .ok();                }),                window,                cx,            )            .detach();        Self::Editor(editor)    }     pub fn empty<V: 'static>(        blur_handler: impl FnMut(&mut V, &mut Window, &mut Context<V>) + 'static,        window: &mut Window,        cx: &mut Context<V>,    ) -> Self {        let head = cx.new(EmptyHead::new);        cx.on_blur(&head.focus_handle(cx), window, blur_handler)            .detach();        Self::Empty(head)    }} /// An invisible element that can hold focus.pub(crate) struct EmptyHead {    focus_handle: FocusHandle,} impl EmptyHead {    fn new(cx: &mut Context<Self>) -> Self {        Self {            focus_handle: cx.focus_handle(),        }    }} impl Render for EmptyHead {    fn render(&mut self, _: &mut Window, cx: &mut Context<Self>) -> impl IntoElement {        div().track_focus(&self.focus_handle(cx))    }} impl Focusable for EmptyHead {    fn focus_handle(&self, _: &App) -> FocusHandle {        self.focus_handle.clone()    }}