app.rs

   1pub mod action;
   2mod callback_collection;
   3mod menu;
   4pub(crate) mod ref_counts;
   5#[cfg(any(test, feature = "test-support"))]
   6pub mod test_app_context;
   7pub(crate) mod window;
   8mod window_input_handler;
   9
  10use std::{
  11    any::{type_name, Any, TypeId},
  12    cell::RefCell,
  13    fmt::{self, Debug},
  14    hash::{Hash, Hasher},
  15    marker::PhantomData,
  16    mem,
  17    ops::{Deref, DerefMut, Range},
  18    path::{Path, PathBuf},
  19    pin::Pin,
  20    rc::{self, Rc},
  21    sync::{Arc, Weak},
  22    time::Duration,
  23};
  24
  25use anyhow::{anyhow, Context, Result};
  26use parking_lot::Mutex;
  27use postage::oneshot;
  28use smallvec::SmallVec;
  29use smol::prelude::*;
  30use util::ResultExt;
  31use uuid::Uuid;
  32
  33pub use action::*;
  34use callback_collection::CallbackCollection;
  35use collections::{hash_map::Entry, BTreeMap, HashMap, HashSet, VecDeque};
  36pub use menu::*;
  37use platform::Event;
  38#[cfg(any(test, feature = "test-support"))]
  39use ref_counts::LeakDetector;
  40#[cfg(any(test, feature = "test-support"))]
  41pub use test_app_context::{ContextHandle, TestAppContext};
  42use window_input_handler::WindowInputHandler;
  43
  44use crate::{
  45    elements::{AnyElement, AnyRootElement, RootElement},
  46    executor::{self, Task},
  47    json,
  48    keymap_matcher::{self, Binding, KeymapContext, KeymapMatcher, Keystroke, MatchResult},
  49    platform::{
  50        self, FontSystem, KeyDownEvent, KeyUpEvent, ModifiersChangedEvent, MouseButton,
  51        PathPromptOptions, Platform, PromptLevel, WindowBounds, WindowOptions,
  52    },
  53    util::post_inc,
  54    window::{Window, WindowContext},
  55    AssetCache, AssetSource, ClipboardItem, FontCache, MouseRegionId,
  56};
  57
  58use self::ref_counts::RefCounts;
  59
  60pub trait Entity: 'static {
  61    type Event;
  62
  63    fn release(&mut self, _: &mut AppContext) {}
  64    fn app_will_quit(
  65        &mut self,
  66        _: &mut AppContext,
  67    ) -> Option<Pin<Box<dyn 'static + Future<Output = ()>>>> {
  68        None
  69    }
  70}
  71
  72pub trait View: Entity + Sized {
  73    fn ui_name() -> &'static str;
  74    fn render(&mut self, cx: &mut ViewContext<'_, '_, Self>) -> AnyElement<Self>;
  75    fn focus_in(&mut self, _: AnyViewHandle, _: &mut ViewContext<Self>) {}
  76    fn focus_out(&mut self, _: AnyViewHandle, _: &mut ViewContext<Self>) {}
  77    fn key_down(&mut self, _: &KeyDownEvent, _: &mut ViewContext<Self>) -> bool {
  78        false
  79    }
  80    fn key_up(&mut self, _: &KeyUpEvent, _: &mut ViewContext<Self>) -> bool {
  81        false
  82    }
  83    fn modifiers_changed(&mut self, _: &ModifiersChangedEvent, _: &mut ViewContext<Self>) -> bool {
  84        false
  85    }
  86
  87    fn update_keymap_context(&self, keymap: &mut keymap_matcher::KeymapContext, _: &AppContext) {
  88        Self::reset_to_default_keymap_context(keymap);
  89    }
  90
  91    fn reset_to_default_keymap_context(keymap: &mut keymap_matcher::KeymapContext) {
  92        keymap.clear();
  93        keymap.add_identifier(Self::ui_name());
  94    }
  95
  96    fn debug_json(&self, _: &AppContext) -> serde_json::Value {
  97        serde_json::Value::Null
  98    }
  99
 100    fn text_for_range(&self, _: Range<usize>, _: &AppContext) -> Option<String> {
 101        None
 102    }
 103    fn selected_text_range(&self, _: &AppContext) -> Option<Range<usize>> {
 104        None
 105    }
 106    fn marked_text_range(&self, _: &AppContext) -> Option<Range<usize>> {
 107        None
 108    }
 109    fn unmark_text(&mut self, _: &mut ViewContext<Self>) {}
 110    fn replace_text_in_range(
 111        &mut self,
 112        _: Option<Range<usize>>,
 113        _: &str,
 114        _: &mut ViewContext<Self>,
 115    ) {
 116    }
 117    fn replace_and_mark_text_in_range(
 118        &mut self,
 119        _: Option<Range<usize>>,
 120        _: &str,
 121        _: Option<Range<usize>>,
 122        _: &mut ViewContext<Self>,
 123    ) {
 124    }
 125}
 126
 127pub trait BorrowAppContext {
 128    fn read_with<T, F: FnOnce(&AppContext) -> T>(&self, f: F) -> T;
 129    fn update<T, F: FnOnce(&mut AppContext) -> T>(&mut self, f: F) -> T;
 130}
 131
 132pub trait BorrowWindowContext {
 133    fn read_with<T, F: FnOnce(&WindowContext) -> T>(&self, window_id: usize, f: F) -> T;
 134    fn update<T, F: FnOnce(&mut WindowContext) -> T>(&mut self, window_id: usize, f: F) -> T;
 135}
 136
 137#[derive(Clone)]
 138pub struct App(Rc<RefCell<AppContext>>);
 139
 140impl App {
 141    pub fn new(asset_source: impl AssetSource) -> Result<Self> {
 142        let platform = platform::current::platform();
 143        let foreground = Rc::new(executor::Foreground::platform(platform.dispatcher())?);
 144        let foreground_platform = platform::current::foreground_platform(foreground.clone());
 145        let app = Self(Rc::new(RefCell::new(AppContext::new(
 146            foreground,
 147            Arc::new(executor::Background::new()),
 148            platform.clone(),
 149            foreground_platform.clone(),
 150            Arc::new(FontCache::new(platform.fonts())),
 151            Default::default(),
 152            asset_source,
 153        ))));
 154
 155        foreground_platform.on_event(Box::new({
 156            let cx = app.0.clone();
 157            move |event| {
 158                if let Event::KeyDown(KeyDownEvent { keystroke, .. }) = &event {
 159                    // Allow system menu "cmd-?" shortcut to be overridden
 160                    if keystroke.cmd
 161                        && !keystroke.shift
 162                        && !keystroke.alt
 163                        && !keystroke.function
 164                        && keystroke.key == "?"
 165                    {
 166                        if cx
 167                            .borrow_mut()
 168                            .update_active_window(|cx| cx.dispatch_keystroke(keystroke))
 169                            .unwrap_or(false)
 170                        {
 171                            return true;
 172                        }
 173                    }
 174                }
 175                false
 176            }
 177        }));
 178        foreground_platform.on_quit(Box::new({
 179            let cx = app.0.clone();
 180            move || {
 181                cx.borrow_mut().quit();
 182            }
 183        }));
 184        setup_menu_handlers(foreground_platform.as_ref(), &app);
 185
 186        app.0.borrow_mut().weak_self = Some(Rc::downgrade(&app.0));
 187        Ok(app)
 188    }
 189
 190    pub fn background(&self) -> Arc<executor::Background> {
 191        self.0.borrow().background().clone()
 192    }
 193
 194    pub fn on_become_active<F>(self, mut callback: F) -> Self
 195    where
 196        F: 'static + FnMut(&mut AppContext),
 197    {
 198        let cx = self.0.clone();
 199        self.0
 200            .borrow_mut()
 201            .foreground_platform
 202            .on_become_active(Box::new(move || callback(&mut *cx.borrow_mut())));
 203        self
 204    }
 205
 206    pub fn on_resign_active<F>(self, mut callback: F) -> Self
 207    where
 208        F: 'static + FnMut(&mut AppContext),
 209    {
 210        let cx = self.0.clone();
 211        self.0
 212            .borrow_mut()
 213            .foreground_platform
 214            .on_resign_active(Box::new(move || callback(&mut *cx.borrow_mut())));
 215        self
 216    }
 217
 218    pub fn on_quit<F>(&mut self, mut callback: F) -> &mut Self
 219    where
 220        F: 'static + FnMut(&mut AppContext),
 221    {
 222        let cx = self.0.clone();
 223        self.0
 224            .borrow_mut()
 225            .foreground_platform
 226            .on_quit(Box::new(move || callback(&mut *cx.borrow_mut())));
 227        self
 228    }
 229
 230    /// Handle the application being re-activated when no windows are open.
 231    pub fn on_reopen<F>(&mut self, mut callback: F) -> &mut Self
 232    where
 233        F: 'static + FnMut(&mut AppContext),
 234    {
 235        let cx = self.0.clone();
 236        self.0
 237            .borrow_mut()
 238            .foreground_platform
 239            .on_reopen(Box::new(move || callback(&mut *cx.borrow_mut())));
 240        self
 241    }
 242
 243    pub fn on_event<F>(&mut self, mut callback: F) -> &mut Self
 244    where
 245        F: 'static + FnMut(Event, &mut AppContext) -> bool,
 246    {
 247        let cx = self.0.clone();
 248        self.0
 249            .borrow_mut()
 250            .foreground_platform
 251            .on_event(Box::new(move |event| {
 252                callback(event, &mut *cx.borrow_mut())
 253            }));
 254        self
 255    }
 256
 257    pub fn on_open_urls<F>(&mut self, mut callback: F) -> &mut Self
 258    where
 259        F: 'static + FnMut(Vec<String>, &mut AppContext),
 260    {
 261        let cx = self.0.clone();
 262        self.0
 263            .borrow_mut()
 264            .foreground_platform
 265            .on_open_urls(Box::new(move |urls| callback(urls, &mut *cx.borrow_mut())));
 266        self
 267    }
 268
 269    pub fn run<F>(self, on_finish_launching: F)
 270    where
 271        F: 'static + FnOnce(&mut AppContext),
 272    {
 273        let platform = self.0.borrow().foreground_platform.clone();
 274        platform.run(Box::new(move || {
 275            let mut cx = self.0.borrow_mut();
 276            let cx = &mut *cx;
 277            crate::views::init(cx);
 278            on_finish_launching(cx);
 279        }))
 280    }
 281
 282    pub fn platform(&self) -> Arc<dyn Platform> {
 283        self.0.borrow().platform.clone()
 284    }
 285
 286    pub fn font_cache(&self) -> Arc<FontCache> {
 287        self.0.borrow().font_cache.clone()
 288    }
 289
 290    fn update<T, F: FnOnce(&mut AppContext) -> T>(&mut self, callback: F) -> T {
 291        let mut state = self.0.borrow_mut();
 292        let result = state.update(callback);
 293        state.pending_notifications.clear();
 294        result
 295    }
 296
 297    fn update_window<T, F: FnOnce(&mut WindowContext) -> T>(
 298        &mut self,
 299        window_id: usize,
 300        callback: F,
 301    ) -> Option<T> {
 302        let mut state = self.0.borrow_mut();
 303        let result = state.update_window(window_id, callback);
 304        state.pending_notifications.clear();
 305        result
 306    }
 307}
 308
 309#[derive(Clone)]
 310pub struct AsyncAppContext(Rc<RefCell<AppContext>>);
 311
 312impl AsyncAppContext {
 313    pub fn spawn<F, Fut, T>(&self, f: F) -> Task<T>
 314    where
 315        F: FnOnce(AsyncAppContext) -> Fut,
 316        Fut: 'static + Future<Output = T>,
 317        T: 'static,
 318    {
 319        self.0.borrow().foreground.spawn(f(self.clone()))
 320    }
 321
 322    pub fn read<T, F: FnOnce(&AppContext) -> T>(&self, callback: F) -> T {
 323        callback(&*self.0.borrow())
 324    }
 325
 326    pub fn update<T, F: FnOnce(&mut AppContext) -> T>(&mut self, callback: F) -> T {
 327        self.0.borrow_mut().update(callback)
 328    }
 329
 330    pub fn read_window<T, F: FnOnce(&WindowContext) -> T>(
 331        &self,
 332        window_id: usize,
 333        callback: F,
 334    ) -> Option<T> {
 335        self.0.borrow_mut().read_window(window_id, callback)
 336    }
 337
 338    pub fn update_window<T, F: FnOnce(&mut WindowContext) -> T>(
 339        &mut self,
 340        window_id: usize,
 341        callback: F,
 342    ) -> Option<T> {
 343        self.0.borrow_mut().update_window(window_id, callback)
 344    }
 345
 346    pub fn debug_elements(&self, window_id: usize) -> Option<json::Value> {
 347        self.0.borrow().read_window(window_id, |cx| {
 348            let root_view = cx.window.root_view();
 349            let root_element = cx.window.rendered_views.get(&root_view.id())?;
 350            root_element.debug(cx).log_err()
 351        })?
 352    }
 353
 354    pub fn dispatch_action(
 355        &mut self,
 356        window_id: usize,
 357        view_id: usize,
 358        action: &dyn Action,
 359    ) -> Result<()> {
 360        self.0
 361            .borrow_mut()
 362            .update_window(window_id, |window| {
 363                window.dispatch_action(Some(view_id), action);
 364            })
 365            .ok_or_else(|| anyhow!("window not found"))
 366    }
 367
 368    pub fn available_actions(
 369        &self,
 370        window_id: usize,
 371        view_id: usize,
 372    ) -> Vec<(&'static str, Box<dyn Action>, SmallVec<[Binding; 1]>)> {
 373        self.read_window(window_id, |cx| cx.available_actions(view_id))
 374            .unwrap_or_default()
 375    }
 376
 377    pub fn has_window(&self, window_id: usize) -> bool {
 378        self.read(|cx| cx.windows.contains_key(&window_id))
 379    }
 380
 381    pub fn window_is_active(&self, window_id: usize) -> bool {
 382        self.read(|cx| cx.windows.get(&window_id).map_or(false, |w| w.is_active))
 383    }
 384
 385    pub fn root_view(&self, window_id: usize) -> Option<AnyViewHandle> {
 386        self.read(|cx| cx.windows.get(&window_id).map(|w| w.root_view().clone()))
 387    }
 388
 389    pub fn window_ids(&self) -> Vec<usize> {
 390        self.read(|cx| cx.windows.keys().copied().collect())
 391    }
 392
 393    pub fn add_model<T, F>(&mut self, build_model: F) -> ModelHandle<T>
 394    where
 395        T: Entity,
 396        F: FnOnce(&mut ModelContext<T>) -> T,
 397    {
 398        self.update(|cx| cx.add_model(build_model))
 399    }
 400
 401    pub fn add_window<T, F>(
 402        &mut self,
 403        window_options: WindowOptions,
 404        build_root_view: F,
 405    ) -> (usize, ViewHandle<T>)
 406    where
 407        T: View,
 408        F: FnOnce(&mut ViewContext<T>) -> T,
 409    {
 410        self.update(|cx| cx.add_window(window_options, build_root_view))
 411    }
 412
 413    pub fn remove_window(&mut self, window_id: usize) {
 414        self.update_window(window_id, |cx| cx.remove_window());
 415    }
 416
 417    pub fn activate_window(&mut self, window_id: usize) {
 418        self.update_window(window_id, |cx| cx.activate_window());
 419    }
 420
 421    // TODO: Can we eliminate this method and move it to WindowContext then call it with update_window?s
 422    pub fn prompt(
 423        &mut self,
 424        window_id: usize,
 425        level: PromptLevel,
 426        msg: &str,
 427        answers: &[&str],
 428    ) -> Option<oneshot::Receiver<usize>> {
 429        self.update_window(window_id, |cx| cx.prompt(level, msg, answers))
 430    }
 431
 432    pub fn platform(&self) -> Arc<dyn Platform> {
 433        self.0.borrow().platform().clone()
 434    }
 435
 436    pub fn foreground(&self) -> Rc<executor::Foreground> {
 437        self.0.borrow().foreground.clone()
 438    }
 439
 440    pub fn background(&self) -> Arc<executor::Background> {
 441        self.0.borrow().background.clone()
 442    }
 443}
 444
 445impl BorrowAppContext for AsyncAppContext {
 446    fn read_with<T, F: FnOnce(&AppContext) -> T>(&self, f: F) -> T {
 447        self.0.borrow().read_with(f)
 448    }
 449
 450    fn update<T, F: FnOnce(&mut AppContext) -> T>(&mut self, f: F) -> T {
 451        self.0.borrow_mut().update(f)
 452    }
 453}
 454
 455type ActionCallback = dyn FnMut(&mut dyn AnyView, &dyn Action, &mut WindowContext, usize);
 456type GlobalActionCallback = dyn FnMut(&dyn Action, &mut AppContext);
 457
 458type SubscriptionCallback = Box<dyn FnMut(&dyn Any, &mut AppContext) -> bool>;
 459type GlobalSubscriptionCallback = Box<dyn FnMut(&dyn Any, &mut AppContext)>;
 460type ObservationCallback = Box<dyn FnMut(&mut AppContext) -> bool>;
 461type GlobalObservationCallback = Box<dyn FnMut(&mut AppContext)>;
 462type FocusObservationCallback = Box<dyn FnMut(bool, &mut WindowContext) -> bool>;
 463type ReleaseObservationCallback = Box<dyn FnMut(&dyn Any, &mut AppContext)>;
 464type ActionObservationCallback = Box<dyn FnMut(TypeId, &mut AppContext)>;
 465type WindowActivationCallback = Box<dyn FnMut(bool, &mut WindowContext) -> bool>;
 466type WindowFullscreenCallback = Box<dyn FnMut(bool, &mut WindowContext) -> bool>;
 467type WindowBoundsCallback = Box<dyn FnMut(WindowBounds, Uuid, &mut WindowContext) -> bool>;
 468type KeystrokeCallback =
 469    Box<dyn FnMut(&Keystroke, &MatchResult, Option<&Box<dyn Action>>, &mut WindowContext) -> bool>;
 470type ActiveLabeledTasksCallback = Box<dyn FnMut(&mut AppContext) -> bool>;
 471type DeserializeActionCallback = fn(json: serde_json::Value) -> anyhow::Result<Box<dyn Action>>;
 472type WindowShouldCloseSubscriptionCallback = Box<dyn FnMut(&mut AppContext) -> bool>;
 473
 474pub struct AppContext {
 475    models: HashMap<usize, Box<dyn AnyModel>>,
 476    views: HashMap<(usize, usize), Box<dyn AnyView>>,
 477    views_metadata: HashMap<(usize, usize), ViewMetadata>,
 478    windows: HashMap<usize, Window>,
 479    globals: HashMap<TypeId, Box<dyn Any>>,
 480    element_states: HashMap<ElementStateId, Box<dyn Any>>,
 481    background: Arc<executor::Background>,
 482    ref_counts: Arc<Mutex<RefCounts>>,
 483
 484    weak_self: Option<rc::Weak<RefCell<Self>>>,
 485    platform: Arc<dyn Platform>,
 486    foreground_platform: Rc<dyn platform::ForegroundPlatform>,
 487    pub asset_cache: Arc<AssetCache>,
 488    font_system: Arc<dyn FontSystem>,
 489    pub font_cache: Arc<FontCache>,
 490    action_deserializers: HashMap<&'static str, (TypeId, DeserializeActionCallback)>,
 491    capture_actions: HashMap<TypeId, HashMap<TypeId, Vec<Box<ActionCallback>>>>,
 492    // Entity Types -> { Action Types -> Action Handlers }
 493    actions: HashMap<TypeId, HashMap<TypeId, Vec<Box<ActionCallback>>>>,
 494    // Action Types -> Action Handlers
 495    global_actions: HashMap<TypeId, Box<GlobalActionCallback>>,
 496    keystroke_matcher: KeymapMatcher,
 497    next_entity_id: usize,
 498    next_window_id: usize,
 499    next_subscription_id: usize,
 500    frame_count: usize,
 501
 502    subscriptions: CallbackCollection<usize, SubscriptionCallback>,
 503    global_subscriptions: CallbackCollection<TypeId, GlobalSubscriptionCallback>,
 504    observations: CallbackCollection<usize, ObservationCallback>,
 505    global_observations: CallbackCollection<TypeId, GlobalObservationCallback>,
 506    focus_observations: CallbackCollection<usize, FocusObservationCallback>,
 507    release_observations: CallbackCollection<usize, ReleaseObservationCallback>,
 508    action_dispatch_observations: CallbackCollection<(), ActionObservationCallback>,
 509    window_activation_observations: CallbackCollection<usize, WindowActivationCallback>,
 510    window_fullscreen_observations: CallbackCollection<usize, WindowFullscreenCallback>,
 511    window_bounds_observations: CallbackCollection<usize, WindowBoundsCallback>,
 512    keystroke_observations: CallbackCollection<usize, KeystrokeCallback>,
 513    active_labeled_task_observations: CallbackCollection<(), ActiveLabeledTasksCallback>,
 514
 515    foreground: Rc<executor::Foreground>,
 516    pending_effects: VecDeque<Effect>,
 517    pending_notifications: HashSet<usize>,
 518    pending_global_notifications: HashSet<TypeId>,
 519    pending_flushes: usize,
 520    flushing_effects: bool,
 521    halt_action_dispatch: bool,
 522    next_labeled_task_id: usize,
 523    active_labeled_tasks: BTreeMap<usize, &'static str>,
 524}
 525
 526impl AppContext {
 527    fn new(
 528        foreground: Rc<executor::Foreground>,
 529        background: Arc<executor::Background>,
 530        platform: Arc<dyn platform::Platform>,
 531        foreground_platform: Rc<dyn platform::ForegroundPlatform>,
 532        font_cache: Arc<FontCache>,
 533        ref_counts: RefCounts,
 534        asset_source: impl AssetSource,
 535    ) -> Self {
 536        Self {
 537            models: Default::default(),
 538            views: Default::default(),
 539            views_metadata: Default::default(),
 540            windows: Default::default(),
 541            globals: Default::default(),
 542            element_states: Default::default(),
 543            ref_counts: Arc::new(Mutex::new(ref_counts)),
 544            background,
 545
 546            weak_self: None,
 547            font_system: platform.fonts(),
 548            platform,
 549            foreground_platform,
 550            font_cache,
 551            asset_cache: Arc::new(AssetCache::new(asset_source)),
 552            action_deserializers: Default::default(),
 553            capture_actions: Default::default(),
 554            actions: Default::default(),
 555            global_actions: Default::default(),
 556            keystroke_matcher: KeymapMatcher::default(),
 557            next_entity_id: 0,
 558            next_window_id: 0,
 559            next_subscription_id: 0,
 560            frame_count: 0,
 561            subscriptions: Default::default(),
 562            global_subscriptions: Default::default(),
 563            observations: Default::default(),
 564            focus_observations: Default::default(),
 565            release_observations: Default::default(),
 566            global_observations: Default::default(),
 567            window_activation_observations: Default::default(),
 568            window_fullscreen_observations: Default::default(),
 569            window_bounds_observations: Default::default(),
 570            keystroke_observations: Default::default(),
 571            action_dispatch_observations: Default::default(),
 572            active_labeled_task_observations: Default::default(),
 573            foreground,
 574            pending_effects: VecDeque::new(),
 575            pending_notifications: Default::default(),
 576            pending_global_notifications: Default::default(),
 577            pending_flushes: 0,
 578            flushing_effects: false,
 579            halt_action_dispatch: false,
 580            next_labeled_task_id: 0,
 581            active_labeled_tasks: Default::default(),
 582        }
 583    }
 584
 585    pub fn background(&self) -> &Arc<executor::Background> {
 586        &self.background
 587    }
 588
 589    pub fn font_cache(&self) -> &Arc<FontCache> {
 590        &self.font_cache
 591    }
 592
 593    pub fn platform(&self) -> &Arc<dyn Platform> {
 594        &self.platform
 595    }
 596
 597    pub fn has_global<T: 'static>(&self) -> bool {
 598        self.globals.contains_key(&TypeId::of::<T>())
 599    }
 600
 601    pub fn global<T: 'static>(&self) -> &T {
 602        if let Some(global) = self.globals.get(&TypeId::of::<T>()) {
 603            global.downcast_ref().unwrap()
 604        } else {
 605            panic!("no global has been added for {}", type_name::<T>());
 606        }
 607    }
 608
 609    pub fn upgrade(&self) -> App {
 610        App(self.weak_self.as_ref().unwrap().upgrade().unwrap())
 611    }
 612
 613    fn quit(&mut self) {
 614        let mut futures = Vec::new();
 615
 616        self.update(|cx| {
 617            for model_id in cx.models.keys().copied().collect::<Vec<_>>() {
 618                let mut model = cx.models.remove(&model_id).unwrap();
 619                futures.extend(model.app_will_quit(cx));
 620                cx.models.insert(model_id, model);
 621            }
 622
 623            for view_id in cx.views.keys().copied().collect::<Vec<_>>() {
 624                let mut view = cx.views.remove(&view_id).unwrap();
 625                futures.extend(view.app_will_quit(cx));
 626                cx.views.insert(view_id, view);
 627            }
 628        });
 629
 630        self.windows.clear();
 631        self.flush_effects();
 632
 633        let futures = futures::future::join_all(futures);
 634        if self
 635            .background
 636            .block_with_timeout(Duration::from_millis(100), futures)
 637            .is_err()
 638        {
 639            log::error!("timed out waiting on app_will_quit");
 640        }
 641    }
 642
 643    pub fn foreground(&self) -> &Rc<executor::Foreground> {
 644        &self.foreground
 645    }
 646
 647    pub fn deserialize_action(
 648        &self,
 649        name: &str,
 650        argument: Option<serde_json::Value>,
 651    ) -> Result<Box<dyn Action>> {
 652        let callback = self
 653            .action_deserializers
 654            .get(name)
 655            .ok_or_else(|| anyhow!("unknown action {}", name))?
 656            .1;
 657        callback(argument.unwrap_or_else(|| serde_json::Value::Object(Default::default())))
 658            .with_context(|| format!("invalid data for action {}", name))
 659    }
 660
 661    pub fn add_action<A, V, F, R>(&mut self, handler: F)
 662    where
 663        A: Action,
 664        V: View,
 665        F: 'static + FnMut(&mut V, &A, &mut ViewContext<V>) -> R,
 666    {
 667        self.add_action_internal(handler, false)
 668    }
 669
 670    pub fn capture_action<A, V, F>(&mut self, handler: F)
 671    where
 672        A: Action,
 673        V: View,
 674        F: 'static + FnMut(&mut V, &A, &mut ViewContext<V>),
 675    {
 676        self.add_action_internal(handler, true)
 677    }
 678
 679    fn add_action_internal<A, V, F, R>(&mut self, mut handler: F, capture: bool)
 680    where
 681        A: Action,
 682        V: View,
 683        F: 'static + FnMut(&mut V, &A, &mut ViewContext<V>) -> R,
 684    {
 685        let handler = Box::new(
 686            move |view: &mut dyn AnyView,
 687                  action: &dyn Action,
 688                  cx: &mut WindowContext,
 689                  view_id: usize| {
 690                let action = action.as_any().downcast_ref().unwrap();
 691                let mut cx = ViewContext::mutable(cx, view_id);
 692                handler(
 693                    view.as_any_mut()
 694                        .downcast_mut()
 695                        .expect("downcast is type safe"),
 696                    action,
 697                    &mut cx,
 698                );
 699            },
 700        );
 701
 702        self.action_deserializers
 703            .entry(A::qualified_name())
 704            .or_insert((TypeId::of::<A>(), A::from_json_str));
 705
 706        let actions = if capture {
 707            &mut self.capture_actions
 708        } else {
 709            &mut self.actions
 710        };
 711
 712        actions
 713            .entry(TypeId::of::<V>())
 714            .or_default()
 715            .entry(TypeId::of::<A>())
 716            .or_default()
 717            .push(handler);
 718    }
 719
 720    pub fn add_async_action<A, V, F>(&mut self, mut handler: F)
 721    where
 722        A: Action,
 723        V: View,
 724        F: 'static + FnMut(&mut V, &A, &mut ViewContext<V>) -> Option<Task<Result<()>>>,
 725    {
 726        self.add_action(move |view, action, cx| {
 727            if let Some(task) = handler(view, action, cx) {
 728                task.detach_and_log_err(cx);
 729            }
 730        })
 731    }
 732
 733    pub fn add_global_action<A, F>(&mut self, mut handler: F)
 734    where
 735        A: Action,
 736        F: 'static + FnMut(&A, &mut AppContext),
 737    {
 738        let handler = Box::new(move |action: &dyn Action, cx: &mut AppContext| {
 739            let action = action.as_any().downcast_ref().unwrap();
 740            handler(action, cx);
 741        });
 742
 743        self.action_deserializers
 744            .entry(A::qualified_name())
 745            .or_insert((TypeId::of::<A>(), A::from_json_str));
 746
 747        if self
 748            .global_actions
 749            .insert(TypeId::of::<A>(), handler)
 750            .is_some()
 751        {
 752            panic!(
 753                "registered multiple global handlers for {}",
 754                type_name::<A>()
 755            );
 756        }
 757    }
 758
 759    pub fn view_ui_name(&self, window_id: usize, view_id: usize) -> Option<&'static str> {
 760        Some(self.views.get(&(window_id, view_id))?.ui_name())
 761    }
 762
 763    pub fn view_type_id(&self, window_id: usize, view_id: usize) -> Option<TypeId> {
 764        self.views_metadata
 765            .get(&(window_id, view_id))
 766            .map(|metadata| metadata.type_id)
 767    }
 768
 769    pub fn active_labeled_tasks<'a>(
 770        &'a self,
 771    ) -> impl DoubleEndedIterator<Item = &'static str> + 'a {
 772        self.active_labeled_tasks.values().cloned()
 773    }
 774
 775    pub(crate) fn start_frame(&mut self) {
 776        self.frame_count += 1;
 777    }
 778
 779    pub fn update<T, F: FnOnce(&mut Self) -> T>(&mut self, callback: F) -> T {
 780        self.pending_flushes += 1;
 781        let result = callback(self);
 782        self.flush_effects();
 783        result
 784    }
 785
 786    pub fn read_window<T, F: FnOnce(&WindowContext) -> T>(
 787        &self,
 788        window_id: usize,
 789        callback: F,
 790    ) -> Option<T> {
 791        let window = self.windows.get(&window_id)?;
 792        let window_context = WindowContext::immutable(self, &window, window_id);
 793        Some(callback(&window_context))
 794    }
 795
 796    pub fn update_window<T, F: FnOnce(&mut WindowContext) -> T>(
 797        &mut self,
 798        window_id: usize,
 799        callback: F,
 800    ) -> Option<T> {
 801        self.update(|app_context| {
 802            let mut window = app_context.windows.remove(&window_id)?;
 803            let mut window_context = WindowContext::mutable(app_context, &mut window, window_id);
 804            let result = callback(&mut window_context);
 805            if !window_context.removed {
 806                app_context.windows.insert(window_id, window);
 807            }
 808            Some(result)
 809        })
 810    }
 811
 812    pub fn update_active_window<T, F: FnOnce(&mut WindowContext) -> T>(
 813        &mut self,
 814        callback: F,
 815    ) -> Option<T> {
 816        self.platform
 817            .main_window_id()
 818            .and_then(|id| self.update_window(id, callback))
 819    }
 820
 821    pub fn prompt_for_paths(
 822        &self,
 823        options: PathPromptOptions,
 824    ) -> oneshot::Receiver<Option<Vec<PathBuf>>> {
 825        self.foreground_platform.prompt_for_paths(options)
 826    }
 827
 828    pub fn prompt_for_new_path(&self, directory: &Path) -> oneshot::Receiver<Option<PathBuf>> {
 829        self.foreground_platform.prompt_for_new_path(directory)
 830    }
 831
 832    pub fn reveal_path(&self, path: &Path) {
 833        self.foreground_platform.reveal_path(path)
 834    }
 835
 836    pub fn emit_global<E: Any>(&mut self, payload: E) {
 837        self.pending_effects.push_back(Effect::GlobalEvent {
 838            payload: Box::new(payload),
 839        });
 840    }
 841
 842    pub fn subscribe<E, H, F>(&mut self, handle: &H, mut callback: F) -> Subscription
 843    where
 844        E: Entity,
 845        E::Event: 'static,
 846        H: Handle<E>,
 847        F: 'static + FnMut(H, &E::Event, &mut Self),
 848    {
 849        self.subscribe_internal(handle, move |handle, event, cx| {
 850            callback(handle, event, cx);
 851            true
 852        })
 853    }
 854
 855    pub fn subscribe_global<E, F>(&mut self, mut callback: F) -> Subscription
 856    where
 857        E: Any,
 858        F: 'static + FnMut(&E, &mut Self),
 859    {
 860        let subscription_id = post_inc(&mut self.next_subscription_id);
 861        let type_id = TypeId::of::<E>();
 862        self.pending_effects.push_back(Effect::GlobalSubscription {
 863            type_id,
 864            subscription_id,
 865            callback: Box::new(move |payload, cx| {
 866                let payload = payload.downcast_ref().expect("downcast is type safe");
 867                callback(payload, cx)
 868            }),
 869        });
 870        Subscription::GlobalSubscription(
 871            self.global_subscriptions
 872                .subscribe(type_id, subscription_id),
 873        )
 874    }
 875
 876    pub fn observe<E, H, F>(&mut self, handle: &H, mut callback: F) -> Subscription
 877    where
 878        E: Entity,
 879        E::Event: 'static,
 880        H: Handle<E>,
 881        F: 'static + FnMut(H, &mut Self),
 882    {
 883        self.observe_internal(handle, move |handle, cx| {
 884            callback(handle, cx);
 885            true
 886        })
 887    }
 888
 889    fn subscribe_internal<E, H, F>(&mut self, handle: &H, mut callback: F) -> Subscription
 890    where
 891        E: Entity,
 892        E::Event: 'static,
 893        H: Handle<E>,
 894        F: 'static + FnMut(H, &E::Event, &mut Self) -> bool,
 895    {
 896        let subscription_id = post_inc(&mut self.next_subscription_id);
 897        let emitter = handle.downgrade();
 898        self.pending_effects.push_back(Effect::Subscription {
 899            entity_id: handle.id(),
 900            subscription_id,
 901            callback: Box::new(move |payload, cx| {
 902                if let Some(emitter) = H::upgrade_from(&emitter, cx) {
 903                    let payload = payload.downcast_ref().expect("downcast is type safe");
 904                    callback(emitter, payload, cx)
 905                } else {
 906                    false
 907                }
 908            }),
 909        });
 910        Subscription::Subscription(self.subscriptions.subscribe(handle.id(), subscription_id))
 911    }
 912
 913    fn observe_internal<E, H, F>(&mut self, handle: &H, mut callback: F) -> Subscription
 914    where
 915        E: Entity,
 916        E::Event: 'static,
 917        H: Handle<E>,
 918        F: 'static + FnMut(H, &mut Self) -> bool,
 919    {
 920        let subscription_id = post_inc(&mut self.next_subscription_id);
 921        let observed = handle.downgrade();
 922        let entity_id = handle.id();
 923        self.pending_effects.push_back(Effect::Observation {
 924            entity_id,
 925            subscription_id,
 926            callback: Box::new(move |cx| {
 927                if let Some(observed) = H::upgrade_from(&observed, cx) {
 928                    callback(observed, cx)
 929                } else {
 930                    false
 931                }
 932            }),
 933        });
 934        Subscription::Observation(self.observations.subscribe(entity_id, subscription_id))
 935    }
 936
 937    fn observe_focus<F, V>(&mut self, handle: &ViewHandle<V>, mut callback: F) -> Subscription
 938    where
 939        F: 'static + FnMut(ViewHandle<V>, bool, &mut WindowContext) -> bool,
 940        V: View,
 941    {
 942        let subscription_id = post_inc(&mut self.next_subscription_id);
 943        let observed = handle.downgrade();
 944        let view_id = handle.id();
 945
 946        self.pending_effects.push_back(Effect::FocusObservation {
 947            view_id,
 948            subscription_id,
 949            callback: Box::new(move |focused, cx| {
 950                if let Some(observed) = observed.upgrade(cx) {
 951                    callback(observed, focused, cx)
 952                } else {
 953                    false
 954                }
 955            }),
 956        });
 957        Subscription::FocusObservation(self.focus_observations.subscribe(view_id, subscription_id))
 958    }
 959
 960    pub fn observe_global<G, F>(&mut self, mut observe: F) -> Subscription
 961    where
 962        G: Any,
 963        F: 'static + FnMut(&mut AppContext),
 964    {
 965        let type_id = TypeId::of::<G>();
 966        let id = post_inc(&mut self.next_subscription_id);
 967
 968        self.global_observations.add_callback(
 969            type_id,
 970            id,
 971            Box::new(move |cx: &mut AppContext| observe(cx)),
 972        );
 973        Subscription::GlobalObservation(self.global_observations.subscribe(type_id, id))
 974    }
 975
 976    pub fn observe_default_global<G, F>(&mut self, observe: F) -> Subscription
 977    where
 978        G: Any + Default,
 979        F: 'static + FnMut(&mut AppContext),
 980    {
 981        if !self.has_global::<G>() {
 982            self.set_global(G::default());
 983        }
 984        self.observe_global::<G, F>(observe)
 985    }
 986
 987    pub fn observe_release<E, H, F>(&mut self, handle: &H, callback: F) -> Subscription
 988    where
 989        E: Entity,
 990        E::Event: 'static,
 991        H: Handle<E>,
 992        F: 'static + FnOnce(&E, &mut Self),
 993    {
 994        let id = post_inc(&mut self.next_subscription_id);
 995        let mut callback = Some(callback);
 996        self.release_observations.add_callback(
 997            handle.id(),
 998            id,
 999            Box::new(move |released, cx| {
1000                let released = released.downcast_ref().unwrap();
1001                if let Some(callback) = callback.take() {
1002                    callback(released, cx)
1003                }
1004            }),
1005        );
1006        Subscription::ReleaseObservation(self.release_observations.subscribe(handle.id(), id))
1007    }
1008
1009    pub fn observe_actions<F>(&mut self, callback: F) -> Subscription
1010    where
1011        F: 'static + FnMut(TypeId, &mut AppContext),
1012    {
1013        let subscription_id = post_inc(&mut self.next_subscription_id);
1014        self.action_dispatch_observations
1015            .add_callback((), subscription_id, Box::new(callback));
1016        Subscription::ActionObservation(
1017            self.action_dispatch_observations
1018                .subscribe((), subscription_id),
1019        )
1020    }
1021
1022    fn observe_active_labeled_tasks<F>(&mut self, callback: F) -> Subscription
1023    where
1024        F: 'static + FnMut(&mut AppContext) -> bool,
1025    {
1026        let subscription_id = post_inc(&mut self.next_subscription_id);
1027        self.active_labeled_task_observations
1028            .add_callback((), subscription_id, Box::new(callback));
1029        Subscription::ActiveLabeledTasksObservation(
1030            self.active_labeled_task_observations
1031                .subscribe((), subscription_id),
1032        )
1033    }
1034
1035    pub fn defer(&mut self, callback: impl 'static + FnOnce(&mut AppContext)) {
1036        self.pending_effects.push_back(Effect::Deferred {
1037            callback: Box::new(callback),
1038            after_window_update: false,
1039        })
1040    }
1041
1042    pub fn after_window_update(&mut self, callback: impl 'static + FnOnce(&mut AppContext)) {
1043        self.pending_effects.push_back(Effect::Deferred {
1044            callback: Box::new(callback),
1045            after_window_update: true,
1046        })
1047    }
1048
1049    fn notify_model(&mut self, model_id: usize) {
1050        if self.pending_notifications.insert(model_id) {
1051            self.pending_effects
1052                .push_back(Effect::ModelNotification { model_id });
1053        }
1054    }
1055
1056    fn notify_view(&mut self, window_id: usize, view_id: usize) {
1057        if self.pending_notifications.insert(view_id) {
1058            self.pending_effects
1059                .push_back(Effect::ViewNotification { window_id, view_id });
1060        }
1061    }
1062
1063    fn notify_global(&mut self, type_id: TypeId) {
1064        if self.pending_global_notifications.insert(type_id) {
1065            self.pending_effects
1066                .push_back(Effect::GlobalNotification { type_id });
1067        }
1068    }
1069
1070    pub fn all_action_names<'a>(&'a self) -> impl Iterator<Item = &'static str> + 'a {
1071        self.action_deserializers.keys().copied()
1072    }
1073
1074    pub fn is_action_available(&self, action: &dyn Action) -> bool {
1075        let mut available_in_window = false;
1076        let action_id = action.id();
1077        if let Some(window_id) = self.platform.main_window_id() {
1078            available_in_window = self
1079                .read_window(window_id, |cx| {
1080                    if let Some(focused_view_id) = cx.focused_view_id() {
1081                        for view_id in cx.ancestors(focused_view_id) {
1082                            if let Some(view_metadata) =
1083                                cx.views_metadata.get(&(window_id, view_id))
1084                            {
1085                                if let Some(actions) = cx.actions.get(&view_metadata.type_id) {
1086                                    if actions.contains_key(&action_id) {
1087                                        return true;
1088                                    }
1089                                }
1090                            }
1091                        }
1092                    }
1093                    false
1094                })
1095                .unwrap_or(false);
1096        }
1097        available_in_window || self.global_actions.contains_key(&action_id)
1098    }
1099
1100    fn actions_mut(
1101        &mut self,
1102        capture_phase: bool,
1103    ) -> &mut HashMap<TypeId, HashMap<TypeId, Vec<Box<ActionCallback>>>> {
1104        if capture_phase {
1105            &mut self.capture_actions
1106        } else {
1107            &mut self.actions
1108        }
1109    }
1110
1111    fn dispatch_global_action_any(&mut self, action: &dyn Action) -> bool {
1112        self.update(|this| {
1113            if let Some((name, mut handler)) = this.global_actions.remove_entry(&action.id()) {
1114                handler(action, this);
1115                this.global_actions.insert(name, handler);
1116                true
1117            } else {
1118                false
1119            }
1120        })
1121    }
1122
1123    pub fn add_bindings<T: IntoIterator<Item = Binding>>(&mut self, bindings: T) {
1124        self.keystroke_matcher.add_bindings(bindings);
1125    }
1126
1127    pub fn clear_bindings(&mut self) {
1128        self.keystroke_matcher.clear_bindings();
1129    }
1130
1131    pub fn default_global<T: 'static + Default>(&mut self) -> &T {
1132        let type_id = TypeId::of::<T>();
1133        self.update(|this| {
1134            if let Entry::Vacant(entry) = this.globals.entry(type_id) {
1135                entry.insert(Box::new(T::default()));
1136                this.notify_global(type_id);
1137            }
1138        });
1139        self.globals.get(&type_id).unwrap().downcast_ref().unwrap()
1140    }
1141
1142    pub fn set_global<T: 'static>(&mut self, state: T) {
1143        self.update(|this| {
1144            let type_id = TypeId::of::<T>();
1145            this.globals.insert(type_id, Box::new(state));
1146            this.notify_global(type_id);
1147        });
1148    }
1149
1150    pub fn update_default_global<T, F, U>(&mut self, update: F) -> U
1151    where
1152        T: 'static + Default,
1153        F: FnOnce(&mut T, &mut AppContext) -> U,
1154    {
1155        self.update(|mut this| {
1156            Self::update_default_global_internal(&mut this, |global, cx| update(global, cx))
1157        })
1158    }
1159
1160    fn update_default_global_internal<C, T, F, U>(this: &mut C, update: F) -> U
1161    where
1162        C: DerefMut<Target = AppContext>,
1163        T: 'static + Default,
1164        F: FnOnce(&mut T, &mut C) -> U,
1165    {
1166        let type_id = TypeId::of::<T>();
1167        let mut state = this
1168            .globals
1169            .remove(&type_id)
1170            .unwrap_or_else(|| Box::new(T::default()));
1171        let result = update(state.downcast_mut().unwrap(), this);
1172        this.globals.insert(type_id, state);
1173        this.notify_global(type_id);
1174        result
1175    }
1176
1177    pub fn update_global<T, F, U>(&mut self, update: F) -> U
1178    where
1179        T: 'static,
1180        F: FnOnce(&mut T, &mut AppContext) -> U,
1181    {
1182        self.update(|mut this| {
1183            Self::update_global_internal(&mut this, |global, cx| update(global, cx))
1184        })
1185    }
1186
1187    fn update_global_internal<C, T, F, U>(this: &mut C, update: F) -> U
1188    where
1189        C: DerefMut<Target = AppContext>,
1190        T: 'static,
1191        F: FnOnce(&mut T, &mut C) -> U,
1192    {
1193        let type_id = TypeId::of::<T>();
1194        if let Some(mut state) = this.globals.remove(&type_id) {
1195            let result = update(state.downcast_mut().unwrap(), this);
1196            this.globals.insert(type_id, state);
1197            this.notify_global(type_id);
1198            result
1199        } else {
1200            panic!("no global added for {}", std::any::type_name::<T>());
1201        }
1202    }
1203
1204    pub fn clear_globals(&mut self) {
1205        self.globals.clear();
1206    }
1207
1208    pub fn remove_global<T: 'static>(&mut self) -> T {
1209        *self
1210            .globals
1211            .remove(&TypeId::of::<T>())
1212            .unwrap_or_else(|| panic!("no global added for {}", std::any::type_name::<T>()))
1213            .downcast()
1214            .unwrap()
1215    }
1216
1217    pub fn add_model<T, F>(&mut self, build_model: F) -> ModelHandle<T>
1218    where
1219        T: Entity,
1220        F: FnOnce(&mut ModelContext<T>) -> T,
1221    {
1222        self.update(|this| {
1223            let model_id = post_inc(&mut this.next_entity_id);
1224            let handle = ModelHandle::new(model_id, &this.ref_counts);
1225            let mut cx = ModelContext::new(this, model_id);
1226            let model = build_model(&mut cx);
1227            this.models.insert(model_id, Box::new(model));
1228            handle
1229        })
1230    }
1231
1232    pub fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T {
1233        if let Some(model) = self.models.get(&handle.model_id) {
1234            model
1235                .as_any()
1236                .downcast_ref()
1237                .expect("downcast is type safe")
1238        } else {
1239            panic!("circular model reference");
1240        }
1241    }
1242
1243    fn update_model<T: Entity, V>(
1244        &mut self,
1245        handle: &ModelHandle<T>,
1246        update: &mut dyn FnMut(&mut T, &mut ModelContext<T>) -> V,
1247    ) -> V {
1248        if let Some(mut model) = self.models.remove(&handle.model_id) {
1249            self.update(|this| {
1250                let mut cx = ModelContext::new(this, handle.model_id);
1251                let result = update(
1252                    model
1253                        .as_any_mut()
1254                        .downcast_mut()
1255                        .expect("downcast is type safe"),
1256                    &mut cx,
1257                );
1258                this.models.insert(handle.model_id, model);
1259                result
1260            })
1261        } else {
1262            panic!("circular model update");
1263        }
1264    }
1265
1266    fn upgrade_model_handle<T: Entity>(
1267        &self,
1268        handle: &WeakModelHandle<T>,
1269    ) -> Option<ModelHandle<T>> {
1270        if self.ref_counts.lock().is_entity_alive(handle.model_id) {
1271            Some(ModelHandle::new(handle.model_id, &self.ref_counts))
1272        } else {
1273            None
1274        }
1275    }
1276
1277    fn model_handle_is_upgradable<T: Entity>(&self, handle: &WeakModelHandle<T>) -> bool {
1278        self.ref_counts.lock().is_entity_alive(handle.model_id)
1279    }
1280
1281    fn upgrade_any_model_handle(&self, handle: &AnyWeakModelHandle) -> Option<AnyModelHandle> {
1282        if self.ref_counts.lock().is_entity_alive(handle.model_id) {
1283            Some(AnyModelHandle::new(
1284                handle.model_id,
1285                handle.model_type,
1286                self.ref_counts.clone(),
1287            ))
1288        } else {
1289            None
1290        }
1291    }
1292
1293    pub fn add_window<V, F>(
1294        &mut self,
1295        window_options: WindowOptions,
1296        build_root_view: F,
1297    ) -> (usize, ViewHandle<V>)
1298    where
1299        V: View,
1300        F: FnOnce(&mut ViewContext<V>) -> V,
1301    {
1302        self.update(|this| {
1303            let window_id = post_inc(&mut this.next_window_id);
1304            let platform_window =
1305                this.platform
1306                    .open_window(window_id, window_options, this.foreground.clone());
1307            let window = this.build_window(window_id, platform_window, build_root_view);
1308            let root_view = window.root_view().clone().downcast::<V>().unwrap();
1309            this.windows.insert(window_id, window);
1310            (window_id, root_view)
1311        })
1312    }
1313
1314    pub fn add_status_bar_item<V, F>(&mut self, build_root_view: F) -> (usize, ViewHandle<V>)
1315    where
1316        V: View,
1317        F: FnOnce(&mut ViewContext<V>) -> V,
1318    {
1319        self.update(|this| {
1320            let window_id = post_inc(&mut this.next_window_id);
1321            let platform_window = this.platform.add_status_item(window_id);
1322            let window = this.build_window(window_id, platform_window, build_root_view);
1323            let root_view = window.root_view().clone().downcast::<V>().unwrap();
1324
1325            this.windows.insert(window_id, window);
1326            this.update_window(window_id, |cx| {
1327                root_view.update(cx, |view, cx| view.focus_in(cx.handle().into_any(), cx))
1328            });
1329
1330            (window_id, root_view)
1331        })
1332    }
1333
1334    pub fn build_window<V, F>(
1335        &mut self,
1336        window_id: usize,
1337        mut platform_window: Box<dyn platform::Window>,
1338        build_root_view: F,
1339    ) -> Window
1340    where
1341        V: View,
1342        F: FnOnce(&mut ViewContext<V>) -> V,
1343    {
1344        {
1345            let mut app = self.upgrade();
1346
1347            platform_window.on_event(Box::new(move |event| {
1348                app.update_window(window_id, |cx| {
1349                    if let Event::KeyDown(KeyDownEvent { keystroke, .. }) = &event {
1350                        if cx.dispatch_keystroke(keystroke) {
1351                            return true;
1352                        }
1353                    }
1354
1355                    cx.dispatch_event(event, false)
1356                })
1357                .unwrap_or(false)
1358            }));
1359        }
1360
1361        {
1362            let mut app = self.upgrade();
1363            platform_window.on_active_status_change(Box::new(move |is_active| {
1364                app.update(|cx| cx.window_changed_active_status(window_id, is_active))
1365            }));
1366        }
1367
1368        {
1369            let mut app = self.upgrade();
1370            platform_window.on_resize(Box::new(move || {
1371                app.update(|cx| cx.window_was_resized(window_id))
1372            }));
1373        }
1374
1375        {
1376            let mut app = self.upgrade();
1377            platform_window.on_moved(Box::new(move || {
1378                app.update(|cx| cx.window_was_moved(window_id))
1379            }));
1380        }
1381
1382        {
1383            let mut app = self.upgrade();
1384            platform_window.on_fullscreen(Box::new(move |is_fullscreen| {
1385                app.update(|cx| cx.window_was_fullscreen_changed(window_id, is_fullscreen))
1386            }));
1387        }
1388
1389        {
1390            let mut app = self.upgrade();
1391            platform_window.on_close(Box::new(move || {
1392                app.update(|cx| cx.update_window(window_id, |cx| cx.remove_window()));
1393            }));
1394        }
1395
1396        {
1397            let mut app = self.upgrade();
1398            platform_window
1399                .on_appearance_changed(Box::new(move || app.update(|cx| cx.refresh_windows())));
1400        }
1401
1402        platform_window.set_input_handler(Box::new(WindowInputHandler {
1403            app: self.upgrade().0,
1404            window_id,
1405        }));
1406
1407        let mut window = Window::new(window_id, platform_window, self, build_root_view);
1408        let mut cx = WindowContext::mutable(self, &mut window, window_id);
1409        cx.layout(false).expect("initial layout should not error");
1410        let scene = cx.paint().expect("initial paint should not error");
1411        window.platform_window.present_scene(scene);
1412        window
1413    }
1414
1415    pub fn replace_root_view<V, F>(
1416        &mut self,
1417        window_id: usize,
1418        build_root_view: F,
1419    ) -> Option<ViewHandle<V>>
1420    where
1421        V: View,
1422        F: FnOnce(&mut ViewContext<V>) -> V,
1423    {
1424        self.update_window(window_id, |cx| cx.replace_root_view(build_root_view))
1425    }
1426
1427    pub fn read_view<T: View>(&self, handle: &ViewHandle<T>) -> &T {
1428        if let Some(view) = self.views.get(&(handle.window_id, handle.view_id)) {
1429            view.as_any().downcast_ref().expect("downcast is type safe")
1430        } else {
1431            panic!("circular view reference for type {}", type_name::<T>());
1432        }
1433    }
1434
1435    fn upgrade_view_handle<T: View>(&self, handle: &WeakViewHandle<T>) -> Option<ViewHandle<T>> {
1436        if self.ref_counts.lock().is_entity_alive(handle.view_id) {
1437            Some(ViewHandle::new(
1438                handle.window_id,
1439                handle.view_id,
1440                &self.ref_counts,
1441            ))
1442        } else {
1443            None
1444        }
1445    }
1446
1447    fn upgrade_any_view_handle(&self, handle: &AnyWeakViewHandle) -> Option<AnyViewHandle> {
1448        if self.ref_counts.lock().is_entity_alive(handle.view_id) {
1449            Some(AnyViewHandle::new(
1450                handle.window_id,
1451                handle.view_id,
1452                handle.view_type,
1453                self.ref_counts.clone(),
1454            ))
1455        } else {
1456            None
1457        }
1458    }
1459
1460    fn remove_dropped_entities(&mut self) {
1461        loop {
1462            let (dropped_models, dropped_views, dropped_element_states) =
1463                self.ref_counts.lock().take_dropped();
1464            if dropped_models.is_empty()
1465                && dropped_views.is_empty()
1466                && dropped_element_states.is_empty()
1467            {
1468                break;
1469            }
1470
1471            for model_id in dropped_models {
1472                self.subscriptions.remove(model_id);
1473                self.observations.remove(model_id);
1474                let mut model = self.models.remove(&model_id).unwrap();
1475                model.release(self);
1476                self.pending_effects
1477                    .push_back(Effect::ModelRelease { model_id, model });
1478            }
1479
1480            for (window_id, view_id) in dropped_views {
1481                self.subscriptions.remove(view_id);
1482                self.observations.remove(view_id);
1483                self.views_metadata.remove(&(window_id, view_id));
1484                let mut view = self.views.remove(&(window_id, view_id)).unwrap();
1485                view.release(self);
1486                if let Some(window) = self.windows.get_mut(&window_id) {
1487                    window.parents.remove(&view_id);
1488                    window
1489                        .invalidation
1490                        .get_or_insert_with(Default::default)
1491                        .removed
1492                        .push(view_id);
1493                }
1494
1495                self.pending_effects
1496                    .push_back(Effect::ViewRelease { view_id, view });
1497            }
1498
1499            for key in dropped_element_states {
1500                self.element_states.remove(&key);
1501            }
1502        }
1503    }
1504
1505    fn flush_effects(&mut self) {
1506        self.pending_flushes = self.pending_flushes.saturating_sub(1);
1507        let mut after_window_update_callbacks = Vec::new();
1508
1509        if !self.flushing_effects && self.pending_flushes == 0 {
1510            self.flushing_effects = true;
1511
1512            let mut refreshing = false;
1513            let mut updated_windows = HashSet::default();
1514            let mut focus_effects = HashMap::<usize, FocusEffect>::default();
1515            loop {
1516                self.remove_dropped_entities();
1517                if let Some(effect) = self.pending_effects.pop_front() {
1518                    match effect {
1519                        Effect::Subscription {
1520                            entity_id,
1521                            subscription_id,
1522                            callback,
1523                        } => self
1524                            .subscriptions
1525                            .add_callback(entity_id, subscription_id, callback),
1526
1527                        Effect::Event { entity_id, payload } => {
1528                            let mut subscriptions = self.subscriptions.clone();
1529                            subscriptions
1530                                .emit(entity_id, |callback| callback(payload.as_ref(), self))
1531                        }
1532
1533                        Effect::GlobalSubscription {
1534                            type_id,
1535                            subscription_id,
1536                            callback,
1537                        } => self.global_subscriptions.add_callback(
1538                            type_id,
1539                            subscription_id,
1540                            callback,
1541                        ),
1542
1543                        Effect::GlobalEvent { payload } => self.emit_global_event(payload),
1544
1545                        Effect::Observation {
1546                            entity_id,
1547                            subscription_id,
1548                            callback,
1549                        } => self
1550                            .observations
1551                            .add_callback(entity_id, subscription_id, callback),
1552
1553                        Effect::ModelNotification { model_id } => {
1554                            let mut observations = self.observations.clone();
1555                            observations.emit(model_id, |callback| callback(self));
1556                        }
1557
1558                        Effect::ViewNotification { window_id, view_id } => {
1559                            self.handle_view_notification_effect(window_id, view_id)
1560                        }
1561
1562                        Effect::GlobalNotification { type_id } => {
1563                            let mut subscriptions = self.global_observations.clone();
1564                            subscriptions.emit(type_id, |callback| {
1565                                callback(self);
1566                                true
1567                            });
1568                        }
1569
1570                        Effect::Deferred {
1571                            callback,
1572                            after_window_update,
1573                        } => {
1574                            if after_window_update {
1575                                after_window_update_callbacks.push(callback);
1576                            } else {
1577                                callback(self)
1578                            }
1579                        }
1580
1581                        Effect::ModelRelease { model_id, model } => {
1582                            self.handle_entity_release_effect(model_id, model.as_any())
1583                        }
1584
1585                        Effect::ViewRelease { view_id, view } => {
1586                            self.handle_entity_release_effect(view_id, view.as_any())
1587                        }
1588
1589                        Effect::Focus(mut effect) => {
1590                            if focus_effects
1591                                .get(&effect.window_id())
1592                                .map_or(false, |prev_effect| prev_effect.is_forced())
1593                            {
1594                                effect.force();
1595                            }
1596
1597                            focus_effects.insert(effect.window_id(), effect);
1598                        }
1599
1600                        Effect::FocusObservation {
1601                            view_id,
1602                            subscription_id,
1603                            callback,
1604                        } => {
1605                            self.focus_observations.add_callback(
1606                                view_id,
1607                                subscription_id,
1608                                callback,
1609                            );
1610                        }
1611
1612                        Effect::ResizeWindow { window_id } => {
1613                            if let Some(window) = self.windows.get_mut(&window_id) {
1614                                window
1615                                    .invalidation
1616                                    .get_or_insert(WindowInvalidation::default());
1617                            }
1618                            self.handle_window_moved(window_id);
1619                        }
1620
1621                        Effect::MoveWindow { window_id } => {
1622                            self.handle_window_moved(window_id);
1623                        }
1624
1625                        Effect::WindowActivationObservation {
1626                            window_id,
1627                            subscription_id,
1628                            callback,
1629                        } => self.window_activation_observations.add_callback(
1630                            window_id,
1631                            subscription_id,
1632                            callback,
1633                        ),
1634
1635                        Effect::ActivateWindow {
1636                            window_id,
1637                            is_active,
1638                        } => {
1639                            if self.handle_window_activation_effect(window_id, is_active)
1640                                && is_active
1641                            {
1642                                focus_effects
1643                                    .entry(window_id)
1644                                    .or_insert_with(|| FocusEffect::View {
1645                                        window_id,
1646                                        view_id: self
1647                                            .read_window(window_id, |cx| cx.focused_view_id())
1648                                            .flatten(),
1649                                        is_forced: true,
1650                                    })
1651                                    .force();
1652                            }
1653                        }
1654
1655                        Effect::WindowFullscreenObservation {
1656                            window_id,
1657                            subscription_id,
1658                            callback,
1659                        } => self.window_fullscreen_observations.add_callback(
1660                            window_id,
1661                            subscription_id,
1662                            callback,
1663                        ),
1664
1665                        Effect::FullscreenWindow {
1666                            window_id,
1667                            is_fullscreen,
1668                        } => self.handle_fullscreen_effect(window_id, is_fullscreen),
1669
1670                        Effect::WindowBoundsObservation {
1671                            window_id,
1672                            subscription_id,
1673                            callback,
1674                        } => self.window_bounds_observations.add_callback(
1675                            window_id,
1676                            subscription_id,
1677                            callback,
1678                        ),
1679
1680                        Effect::RefreshWindows => {
1681                            refreshing = true;
1682                        }
1683
1684                        Effect::ActionDispatchNotification { action_id } => {
1685                            self.handle_action_dispatch_notification_effect(action_id)
1686                        }
1687                        Effect::WindowShouldCloseSubscription {
1688                            window_id,
1689                            callback,
1690                        } => {
1691                            self.handle_window_should_close_subscription_effect(window_id, callback)
1692                        }
1693                        Effect::Keystroke {
1694                            window_id,
1695                            keystroke,
1696                            handled_by,
1697                            result,
1698                        } => self.handle_keystroke_effect(window_id, keystroke, handled_by, result),
1699                        Effect::ActiveLabeledTasksChanged => {
1700                            self.handle_active_labeled_tasks_changed_effect()
1701                        }
1702                        Effect::ActiveLabeledTasksObservation {
1703                            subscription_id,
1704                            callback,
1705                        } => self.active_labeled_task_observations.add_callback(
1706                            (),
1707                            subscription_id,
1708                            callback,
1709                        ),
1710                    }
1711                    self.pending_notifications.clear();
1712                } else {
1713                    for window_id in self.windows.keys().cloned().collect::<Vec<_>>() {
1714                        self.update_window(window_id, |cx| {
1715                            let invalidation = if refreshing {
1716                                let mut invalidation =
1717                                    cx.window.invalidation.take().unwrap_or_default();
1718                                invalidation
1719                                    .updated
1720                                    .extend(cx.window.rendered_views.keys().copied());
1721                                Some(invalidation)
1722                            } else {
1723                                cx.window.invalidation.take()
1724                            };
1725
1726                            if let Some(invalidation) = invalidation {
1727                                let appearance = cx.window.platform_window.appearance();
1728                                cx.invalidate(invalidation, appearance);
1729                                if let Some(old_parents) = cx.layout(refreshing).log_err() {
1730                                    updated_windows.insert(window_id);
1731
1732                                    if let Some(focused_view_id) = cx.focused_view_id() {
1733                                        let old_ancestors = std::iter::successors(
1734                                            Some(focused_view_id),
1735                                            |&view_id| old_parents.get(&view_id).copied(),
1736                                        )
1737                                        .collect::<HashSet<_>>();
1738                                        let new_ancestors =
1739                                            cx.ancestors(focused_view_id).collect::<HashSet<_>>();
1740
1741                                        // Notify the old ancestors of the focused view when they don't contain it anymore.
1742                                        for old_ancestor in old_ancestors.iter().copied() {
1743                                            if !new_ancestors.contains(&old_ancestor) {
1744                                                if let Some(mut view) =
1745                                                    cx.views.remove(&(window_id, old_ancestor))
1746                                                {
1747                                                    view.focus_out(
1748                                                        focused_view_id,
1749                                                        cx,
1750                                                        old_ancestor,
1751                                                    );
1752                                                    cx.views
1753                                                        .insert((window_id, old_ancestor), view);
1754                                                }
1755                                            }
1756                                        }
1757
1758                                        // Notify the new ancestors of the focused view if they contain it now.
1759                                        for new_ancestor in new_ancestors.iter().copied() {
1760                                            if !old_ancestors.contains(&new_ancestor) {
1761                                                if let Some(mut view) =
1762                                                    cx.views.remove(&(window_id, new_ancestor))
1763                                                {
1764                                                    view.focus_in(
1765                                                        focused_view_id,
1766                                                        cx,
1767                                                        new_ancestor,
1768                                                    );
1769                                                    cx.views
1770                                                        .insert((window_id, new_ancestor), view);
1771                                                }
1772                                            }
1773                                        }
1774
1775                                        // When the previously-focused view has been dropped and
1776                                        // there isn't any pending focus, focus the root view.
1777                                        let root_view_id = cx.window.root_view().id();
1778                                        if focused_view_id != root_view_id
1779                                            && !cx.views.contains_key(&(window_id, focused_view_id))
1780                                            && !focus_effects.contains_key(&window_id)
1781                                        {
1782                                            focus_effects.insert(
1783                                                window_id,
1784                                                FocusEffect::View {
1785                                                    window_id,
1786                                                    view_id: Some(root_view_id),
1787                                                    is_forced: false,
1788                                                },
1789                                            );
1790                                        }
1791                                    }
1792                                }
1793                            }
1794                        });
1795                    }
1796
1797                    for (_, effect) in focus_effects.drain() {
1798                        self.handle_focus_effect(effect);
1799                    }
1800
1801                    if self.pending_effects.is_empty() {
1802                        for callback in after_window_update_callbacks.drain(..) {
1803                            callback(self);
1804                        }
1805
1806                        for window_id in updated_windows.drain() {
1807                            self.update_window(window_id, |cx| {
1808                                if let Some(scene) = cx.paint().log_err() {
1809                                    cx.window.platform_window.present_scene(scene);
1810                                }
1811                            });
1812                        }
1813
1814                        if self.pending_effects.is_empty() {
1815                            self.flushing_effects = false;
1816                            self.pending_notifications.clear();
1817                            self.pending_global_notifications.clear();
1818                            break;
1819                        }
1820                    }
1821
1822                    refreshing = false;
1823                }
1824            }
1825        }
1826    }
1827
1828    fn window_was_resized(&mut self, window_id: usize) {
1829        self.pending_effects
1830            .push_back(Effect::ResizeWindow { window_id });
1831    }
1832
1833    fn window_was_moved(&mut self, window_id: usize) {
1834        self.pending_effects
1835            .push_back(Effect::MoveWindow { window_id });
1836    }
1837
1838    fn window_was_fullscreen_changed(&mut self, window_id: usize, is_fullscreen: bool) {
1839        self.pending_effects.push_back(Effect::FullscreenWindow {
1840            window_id,
1841            is_fullscreen,
1842        });
1843    }
1844
1845    fn window_changed_active_status(&mut self, window_id: usize, is_active: bool) {
1846        self.pending_effects.push_back(Effect::ActivateWindow {
1847            window_id,
1848            is_active,
1849        });
1850    }
1851
1852    fn keystroke(
1853        &mut self,
1854        window_id: usize,
1855        keystroke: Keystroke,
1856        handled_by: Option<Box<dyn Action>>,
1857        result: MatchResult,
1858    ) {
1859        self.pending_effects.push_back(Effect::Keystroke {
1860            window_id,
1861            keystroke,
1862            handled_by,
1863            result,
1864        });
1865    }
1866
1867    pub fn refresh_windows(&mut self) {
1868        self.pending_effects.push_back(Effect::RefreshWindows);
1869    }
1870
1871    fn emit_global_event(&mut self, payload: Box<dyn Any>) {
1872        let type_id = (&*payload).type_id();
1873
1874        let mut subscriptions = self.global_subscriptions.clone();
1875        subscriptions.emit(type_id, |callback| {
1876            callback(payload.as_ref(), self);
1877            true //Always alive
1878        });
1879    }
1880
1881    fn handle_view_notification_effect(
1882        &mut self,
1883        observed_window_id: usize,
1884        observed_view_id: usize,
1885    ) {
1886        let view_key = (observed_window_id, observed_view_id);
1887        if let Some((view, mut view_metadata)) = self
1888            .views
1889            .remove(&view_key)
1890            .zip(self.views_metadata.remove(&view_key))
1891        {
1892            if let Some(window) = self.windows.get_mut(&observed_window_id) {
1893                window
1894                    .invalidation
1895                    .get_or_insert_with(Default::default)
1896                    .updated
1897                    .insert(observed_view_id);
1898            }
1899
1900            view.update_keymap_context(&mut view_metadata.keymap_context, self);
1901            self.views.insert(view_key, view);
1902            self.views_metadata.insert(view_key, view_metadata);
1903
1904            let mut observations = self.observations.clone();
1905            observations.emit(observed_view_id, |callback| callback(self));
1906        }
1907    }
1908
1909    fn handle_entity_release_effect(&mut self, entity_id: usize, entity: &dyn Any) {
1910        self.release_observations
1911            .clone()
1912            .emit(entity_id, |callback| {
1913                callback(entity, self);
1914                // Release observations happen one time. So clear the callback by returning false
1915                false
1916            })
1917    }
1918
1919    fn handle_fullscreen_effect(&mut self, window_id: usize, is_fullscreen: bool) {
1920        self.update_window(window_id, |cx| {
1921            cx.window.is_fullscreen = is_fullscreen;
1922
1923            let mut fullscreen_observations = cx.window_fullscreen_observations.clone();
1924            fullscreen_observations.emit(window_id, |callback| callback(is_fullscreen, cx));
1925
1926            if let Some(uuid) = cx.window_display_uuid() {
1927                let bounds = cx.window_bounds();
1928                let mut bounds_observations = cx.window_bounds_observations.clone();
1929                bounds_observations.emit(window_id, |callback| callback(bounds, uuid, cx));
1930            }
1931
1932            Some(())
1933        });
1934    }
1935
1936    fn handle_keystroke_effect(
1937        &mut self,
1938        window_id: usize,
1939        keystroke: Keystroke,
1940        handled_by: Option<Box<dyn Action>>,
1941        result: MatchResult,
1942    ) {
1943        self.update_window(window_id, |cx| {
1944            let mut observations = cx.keystroke_observations.clone();
1945            observations.emit(window_id, move |callback| {
1946                callback(&keystroke, &result, handled_by.as_ref(), cx)
1947            });
1948        });
1949    }
1950
1951    fn handle_window_activation_effect(&mut self, window_id: usize, active: bool) -> bool {
1952        self.update_window(window_id, |cx| {
1953            if cx.window.is_active == active {
1954                return false;
1955            }
1956            cx.window.is_active = active;
1957
1958            let mut observations = cx.window_activation_observations.clone();
1959            observations.emit(window_id, |callback| callback(active, cx));
1960            true
1961        })
1962        .unwrap_or(false)
1963    }
1964
1965    fn handle_focus_effect(&mut self, effect: FocusEffect) {
1966        let window_id = effect.window_id();
1967        self.update_window(window_id, |cx| {
1968            // Ensure the newly-focused view still exists, otherwise focus
1969            // the root view instead.
1970            let focused_id = match effect {
1971                FocusEffect::View { view_id, .. } => {
1972                    if let Some(view_id) = view_id {
1973                        if cx.views.contains_key(&(window_id, view_id)) {
1974                            Some(view_id)
1975                        } else {
1976                            Some(cx.root_view().id())
1977                        }
1978                    } else {
1979                        None
1980                    }
1981                }
1982                FocusEffect::ViewParent { view_id, .. } => Some(
1983                    cx.window
1984                        .parents
1985                        .get(&view_id)
1986                        .copied()
1987                        .unwrap_or(cx.root_view().id()),
1988                ),
1989            };
1990
1991            let focus_changed = cx.window.focused_view_id != focused_id;
1992            let blurred_id = cx.window.focused_view_id;
1993            cx.window.focused_view_id = focused_id;
1994
1995            if focus_changed {
1996                if let Some(blurred_id) = blurred_id {
1997                    for view_id in cx.ancestors(blurred_id).collect::<Vec<_>>() {
1998                        if let Some(mut view) = cx.views.remove(&(window_id, view_id)) {
1999                            view.focus_out(blurred_id, cx, view_id);
2000                            cx.views.insert((window_id, view_id), view);
2001                        }
2002                    }
2003
2004                    let mut subscriptions = cx.focus_observations.clone();
2005                    subscriptions.emit(blurred_id, |callback| callback(false, cx));
2006                }
2007            }
2008
2009            if focus_changed || effect.is_forced() {
2010                if let Some(focused_id) = focused_id {
2011                    for view_id in cx.ancestors(focused_id).collect::<Vec<_>>() {
2012                        if let Some(mut view) = cx.views.remove(&(window_id, view_id)) {
2013                            view.focus_in(focused_id, cx, view_id);
2014                            cx.views.insert((window_id, view_id), view);
2015                        }
2016                    }
2017
2018                    let mut subscriptions = cx.focus_observations.clone();
2019                    subscriptions.emit(focused_id, |callback| callback(true, cx));
2020                }
2021            }
2022        });
2023    }
2024
2025    fn handle_action_dispatch_notification_effect(&mut self, action_id: TypeId) {
2026        self.action_dispatch_observations
2027            .clone()
2028            .emit((), |callback| {
2029                callback(action_id, self);
2030                true
2031            });
2032    }
2033
2034    fn handle_window_should_close_subscription_effect(
2035        &mut self,
2036        window_id: usize,
2037        mut callback: WindowShouldCloseSubscriptionCallback,
2038    ) {
2039        let mut app = self.upgrade();
2040        if let Some(window) = self.windows.get_mut(&window_id) {
2041            window
2042                .platform_window
2043                .on_should_close(Box::new(move || app.update(|cx| callback(cx))))
2044        }
2045    }
2046
2047    fn handle_window_moved(&mut self, window_id: usize) {
2048        self.update_window(window_id, |cx| {
2049            if let Some(display) = cx.window_display_uuid() {
2050                let bounds = cx.window_bounds();
2051                cx.window_bounds_observations
2052                    .clone()
2053                    .emit(window_id, move |callback| {
2054                        callback(bounds, display, cx);
2055                        true
2056                    });
2057            }
2058        });
2059    }
2060
2061    fn handle_active_labeled_tasks_changed_effect(&mut self) {
2062        self.active_labeled_task_observations
2063            .clone()
2064            .emit((), move |callback| {
2065                callback(self);
2066                true
2067            });
2068    }
2069
2070    pub fn focus(&mut self, window_id: usize, view_id: Option<usize>) {
2071        self.pending_effects
2072            .push_back(Effect::Focus(FocusEffect::View {
2073                window_id,
2074                view_id,
2075                is_forced: false,
2076            }));
2077    }
2078
2079    fn spawn_internal<F, Fut, T>(&mut self, task_name: Option<&'static str>, f: F) -> Task<T>
2080    where
2081        F: FnOnce(AsyncAppContext) -> Fut,
2082        Fut: 'static + Future<Output = T>,
2083        T: 'static,
2084    {
2085        let label_id = task_name.map(|task_name| {
2086            let id = post_inc(&mut self.next_labeled_task_id);
2087            self.active_labeled_tasks.insert(id, task_name);
2088            self.pending_effects
2089                .push_back(Effect::ActiveLabeledTasksChanged);
2090            id
2091        });
2092
2093        let future = f(self.to_async());
2094        let cx = self.to_async();
2095        self.foreground.spawn(async move {
2096            let result = future.await;
2097            let mut cx = cx.0.borrow_mut();
2098
2099            if let Some(completed_label_id) = label_id {
2100                cx.active_labeled_tasks.remove(&completed_label_id);
2101                cx.pending_effects
2102                    .push_back(Effect::ActiveLabeledTasksChanged);
2103            }
2104            cx.flush_effects();
2105            result
2106        })
2107    }
2108
2109    pub fn spawn_labeled<F, Fut, T>(&mut self, task_name: &'static str, f: F) -> Task<T>
2110    where
2111        F: FnOnce(AsyncAppContext) -> Fut,
2112        Fut: 'static + Future<Output = T>,
2113        T: 'static,
2114    {
2115        self.spawn_internal(Some(task_name), f)
2116    }
2117
2118    pub fn spawn<F, Fut, T>(&mut self, f: F) -> Task<T>
2119    where
2120        F: FnOnce(AsyncAppContext) -> Fut,
2121        Fut: 'static + Future<Output = T>,
2122        T: 'static,
2123    {
2124        self.spawn_internal(None, f)
2125    }
2126
2127    pub fn to_async(&self) -> AsyncAppContext {
2128        AsyncAppContext(self.weak_self.as_ref().unwrap().upgrade().unwrap())
2129    }
2130
2131    pub fn write_to_clipboard(&self, item: ClipboardItem) {
2132        self.platform.write_to_clipboard(item);
2133    }
2134
2135    pub fn read_from_clipboard(&self) -> Option<ClipboardItem> {
2136        self.platform.read_from_clipboard()
2137    }
2138
2139    #[cfg(any(test, feature = "test-support"))]
2140    pub fn leak_detector(&self) -> Arc<Mutex<LeakDetector>> {
2141        self.ref_counts.lock().leak_detector.clone()
2142    }
2143}
2144
2145impl BorrowAppContext for AppContext {
2146    fn read_with<T, F: FnOnce(&AppContext) -> T>(&self, f: F) -> T {
2147        f(self)
2148    }
2149
2150    fn update<T, F: FnOnce(&mut AppContext) -> T>(&mut self, f: F) -> T {
2151        f(self)
2152    }
2153}
2154
2155#[derive(Debug)]
2156pub enum ParentId {
2157    View(usize),
2158    Root,
2159}
2160
2161struct ViewMetadata {
2162    type_id: TypeId,
2163    keymap_context: KeymapContext,
2164}
2165
2166#[derive(Default, Clone)]
2167pub struct WindowInvalidation {
2168    pub updated: HashSet<usize>,
2169    pub removed: Vec<usize>,
2170}
2171
2172#[derive(Debug)]
2173pub enum FocusEffect {
2174    View {
2175        window_id: usize,
2176        view_id: Option<usize>,
2177        is_forced: bool,
2178    },
2179    ViewParent {
2180        window_id: usize,
2181        view_id: usize,
2182        is_forced: bool,
2183    },
2184}
2185
2186impl FocusEffect {
2187    fn window_id(&self) -> usize {
2188        match self {
2189            FocusEffect::View { window_id, .. } => *window_id,
2190            FocusEffect::ViewParent { window_id, .. } => *window_id,
2191        }
2192    }
2193
2194    fn is_forced(&self) -> bool {
2195        match self {
2196            FocusEffect::View { is_forced, .. } => *is_forced,
2197            FocusEffect::ViewParent { is_forced, .. } => *is_forced,
2198        }
2199    }
2200
2201    fn force(&mut self) {
2202        match self {
2203            FocusEffect::View { is_forced, .. } => *is_forced = true,
2204            FocusEffect::ViewParent { is_forced, .. } => *is_forced = true,
2205        }
2206    }
2207}
2208
2209pub enum Effect {
2210    Subscription {
2211        entity_id: usize,
2212        subscription_id: usize,
2213        callback: SubscriptionCallback,
2214    },
2215    Event {
2216        entity_id: usize,
2217        payload: Box<dyn Any>,
2218    },
2219    GlobalSubscription {
2220        type_id: TypeId,
2221        subscription_id: usize,
2222        callback: GlobalSubscriptionCallback,
2223    },
2224    GlobalEvent {
2225        payload: Box<dyn Any>,
2226    },
2227    Observation {
2228        entity_id: usize,
2229        subscription_id: usize,
2230        callback: ObservationCallback,
2231    },
2232    ModelNotification {
2233        model_id: usize,
2234    },
2235    ViewNotification {
2236        window_id: usize,
2237        view_id: usize,
2238    },
2239    Deferred {
2240        callback: Box<dyn FnOnce(&mut AppContext)>,
2241        after_window_update: bool,
2242    },
2243    GlobalNotification {
2244        type_id: TypeId,
2245    },
2246    ModelRelease {
2247        model_id: usize,
2248        model: Box<dyn AnyModel>,
2249    },
2250    ViewRelease {
2251        view_id: usize,
2252        view: Box<dyn AnyView>,
2253    },
2254    Focus(FocusEffect),
2255    FocusObservation {
2256        view_id: usize,
2257        subscription_id: usize,
2258        callback: FocusObservationCallback,
2259    },
2260    ResizeWindow {
2261        window_id: usize,
2262    },
2263    MoveWindow {
2264        window_id: usize,
2265    },
2266    ActivateWindow {
2267        window_id: usize,
2268        is_active: bool,
2269    },
2270    WindowActivationObservation {
2271        window_id: usize,
2272        subscription_id: usize,
2273        callback: WindowActivationCallback,
2274    },
2275    FullscreenWindow {
2276        window_id: usize,
2277        is_fullscreen: bool,
2278    },
2279    WindowFullscreenObservation {
2280        window_id: usize,
2281        subscription_id: usize,
2282        callback: WindowFullscreenCallback,
2283    },
2284    WindowBoundsObservation {
2285        window_id: usize,
2286        subscription_id: usize,
2287        callback: WindowBoundsCallback,
2288    },
2289    Keystroke {
2290        window_id: usize,
2291        keystroke: Keystroke,
2292        handled_by: Option<Box<dyn Action>>,
2293        result: MatchResult,
2294    },
2295    RefreshWindows,
2296    ActionDispatchNotification {
2297        action_id: TypeId,
2298    },
2299    WindowShouldCloseSubscription {
2300        window_id: usize,
2301        callback: WindowShouldCloseSubscriptionCallback,
2302    },
2303    ActiveLabeledTasksChanged,
2304    ActiveLabeledTasksObservation {
2305        subscription_id: usize,
2306        callback: ActiveLabeledTasksCallback,
2307    },
2308}
2309
2310impl Debug for Effect {
2311    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2312        match self {
2313            Effect::Subscription {
2314                entity_id,
2315                subscription_id,
2316                ..
2317            } => f
2318                .debug_struct("Effect::Subscribe")
2319                .field("entity_id", entity_id)
2320                .field("subscription_id", subscription_id)
2321                .finish(),
2322            Effect::Event { entity_id, .. } => f
2323                .debug_struct("Effect::Event")
2324                .field("entity_id", entity_id)
2325                .finish(),
2326            Effect::GlobalSubscription {
2327                type_id,
2328                subscription_id,
2329                ..
2330            } => f
2331                .debug_struct("Effect::Subscribe")
2332                .field("type_id", type_id)
2333                .field("subscription_id", subscription_id)
2334                .finish(),
2335            Effect::GlobalEvent { payload, .. } => f
2336                .debug_struct("Effect::GlobalEvent")
2337                .field("type_id", &(&*payload).type_id())
2338                .finish(),
2339            Effect::Observation {
2340                entity_id,
2341                subscription_id,
2342                ..
2343            } => f
2344                .debug_struct("Effect::Observation")
2345                .field("entity_id", entity_id)
2346                .field("subscription_id", subscription_id)
2347                .finish(),
2348            Effect::ModelNotification { model_id } => f
2349                .debug_struct("Effect::ModelNotification")
2350                .field("model_id", model_id)
2351                .finish(),
2352            Effect::ViewNotification { window_id, view_id } => f
2353                .debug_struct("Effect::ViewNotification")
2354                .field("window_id", window_id)
2355                .field("view_id", view_id)
2356                .finish(),
2357            Effect::GlobalNotification { type_id } => f
2358                .debug_struct("Effect::GlobalNotification")
2359                .field("type_id", type_id)
2360                .finish(),
2361            Effect::Deferred { .. } => f.debug_struct("Effect::Deferred").finish(),
2362            Effect::ModelRelease { model_id, .. } => f
2363                .debug_struct("Effect::ModelRelease")
2364                .field("model_id", model_id)
2365                .finish(),
2366            Effect::ViewRelease { view_id, .. } => f
2367                .debug_struct("Effect::ViewRelease")
2368                .field("view_id", view_id)
2369                .finish(),
2370            Effect::Focus(focus) => f.debug_tuple("Effect::Focus").field(focus).finish(),
2371            Effect::FocusObservation {
2372                view_id,
2373                subscription_id,
2374                ..
2375            } => f
2376                .debug_struct("Effect::FocusObservation")
2377                .field("view_id", view_id)
2378                .field("subscription_id", subscription_id)
2379                .finish(),
2380            Effect::ActionDispatchNotification { action_id, .. } => f
2381                .debug_struct("Effect::ActionDispatchNotification")
2382                .field("action_id", action_id)
2383                .finish(),
2384            Effect::ResizeWindow { window_id } => f
2385                .debug_struct("Effect::RefreshWindow")
2386                .field("window_id", window_id)
2387                .finish(),
2388            Effect::MoveWindow { window_id } => f
2389                .debug_struct("Effect::MoveWindow")
2390                .field("window_id", window_id)
2391                .finish(),
2392            Effect::WindowActivationObservation {
2393                window_id,
2394                subscription_id,
2395                ..
2396            } => f
2397                .debug_struct("Effect::WindowActivationObservation")
2398                .field("window_id", window_id)
2399                .field("subscription_id", subscription_id)
2400                .finish(),
2401            Effect::ActivateWindow {
2402                window_id,
2403                is_active,
2404            } => f
2405                .debug_struct("Effect::ActivateWindow")
2406                .field("window_id", window_id)
2407                .field("is_active", is_active)
2408                .finish(),
2409            Effect::FullscreenWindow {
2410                window_id,
2411                is_fullscreen,
2412            } => f
2413                .debug_struct("Effect::FullscreenWindow")
2414                .field("window_id", window_id)
2415                .field("is_fullscreen", is_fullscreen)
2416                .finish(),
2417            Effect::WindowFullscreenObservation {
2418                window_id,
2419                subscription_id,
2420                callback: _,
2421            } => f
2422                .debug_struct("Effect::WindowFullscreenObservation")
2423                .field("window_id", window_id)
2424                .field("subscription_id", subscription_id)
2425                .finish(),
2426
2427            Effect::WindowBoundsObservation {
2428                window_id,
2429                subscription_id,
2430                callback: _,
2431            } => f
2432                .debug_struct("Effect::WindowBoundsObservation")
2433                .field("window_id", window_id)
2434                .field("subscription_id", subscription_id)
2435                .finish(),
2436            Effect::RefreshWindows => f.debug_struct("Effect::FullViewRefresh").finish(),
2437            Effect::WindowShouldCloseSubscription { window_id, .. } => f
2438                .debug_struct("Effect::WindowShouldCloseSubscription")
2439                .field("window_id", window_id)
2440                .finish(),
2441            Effect::Keystroke {
2442                window_id,
2443                keystroke,
2444                handled_by,
2445                result,
2446            } => f
2447                .debug_struct("Effect::Keystroke")
2448                .field("window_id", window_id)
2449                .field("keystroke", keystroke)
2450                .field(
2451                    "keystroke",
2452                    &handled_by.as_ref().map(|handled_by| handled_by.name()),
2453                )
2454                .field("result", result)
2455                .finish(),
2456            Effect::ActiveLabeledTasksChanged => {
2457                f.debug_struct("Effect::ActiveLabeledTasksChanged").finish()
2458            }
2459            Effect::ActiveLabeledTasksObservation {
2460                subscription_id,
2461                callback: _,
2462            } => f
2463                .debug_struct("Effect::ActiveLabeledTasksObservation")
2464                .field("subscription_id", subscription_id)
2465                .finish(),
2466        }
2467    }
2468}
2469
2470pub trait AnyModel {
2471    fn as_any(&self) -> &dyn Any;
2472    fn as_any_mut(&mut self) -> &mut dyn Any;
2473    fn release(&mut self, cx: &mut AppContext);
2474    fn app_will_quit(
2475        &mut self,
2476        cx: &mut AppContext,
2477    ) -> Option<Pin<Box<dyn 'static + Future<Output = ()>>>>;
2478}
2479
2480impl<T> AnyModel for T
2481where
2482    T: Entity,
2483{
2484    fn as_any(&self) -> &dyn Any {
2485        self
2486    }
2487
2488    fn as_any_mut(&mut self) -> &mut dyn Any {
2489        self
2490    }
2491
2492    fn release(&mut self, cx: &mut AppContext) {
2493        self.release(cx);
2494    }
2495
2496    fn app_will_quit(
2497        &mut self,
2498        cx: &mut AppContext,
2499    ) -> Option<Pin<Box<dyn 'static + Future<Output = ()>>>> {
2500        self.app_will_quit(cx)
2501    }
2502}
2503
2504pub trait AnyView {
2505    fn as_any(&self) -> &dyn Any;
2506    fn as_any_mut(&mut self) -> &mut dyn Any;
2507    fn release(&mut self, cx: &mut AppContext);
2508    fn app_will_quit(
2509        &mut self,
2510        cx: &mut AppContext,
2511    ) -> Option<Pin<Box<dyn 'static + Future<Output = ()>>>>;
2512    fn ui_name(&self) -> &'static str;
2513    fn render(&mut self, cx: &mut WindowContext, view_id: usize) -> Box<dyn AnyRootElement>;
2514    fn focus_in<'a, 'b>(&mut self, focused_id: usize, cx: &mut WindowContext<'a>, view_id: usize);
2515    fn focus_out(&mut self, focused_id: usize, cx: &mut WindowContext, view_id: usize);
2516    fn key_down(&mut self, event: &KeyDownEvent, cx: &mut WindowContext, view_id: usize) -> bool;
2517    fn key_up(&mut self, event: &KeyUpEvent, cx: &mut WindowContext, view_id: usize) -> bool;
2518    fn modifiers_changed(
2519        &mut self,
2520        event: &ModifiersChangedEvent,
2521        cx: &mut WindowContext,
2522        view_id: usize,
2523    ) -> bool;
2524    fn update_keymap_context(&self, keymap: &mut KeymapContext, cx: &AppContext);
2525    fn debug_json(&self, cx: &WindowContext) -> serde_json::Value;
2526
2527    fn text_for_range(&self, range: Range<usize>, cx: &WindowContext) -> Option<String>;
2528    fn selected_text_range(&self, cx: &WindowContext) -> Option<Range<usize>>;
2529    fn marked_text_range(&self, cx: &WindowContext) -> Option<Range<usize>>;
2530    fn unmark_text(&mut self, cx: &mut WindowContext, view_id: usize);
2531    fn replace_text_in_range(
2532        &mut self,
2533        range: Option<Range<usize>>,
2534        text: &str,
2535        cx: &mut WindowContext,
2536        view_id: usize,
2537    );
2538    fn replace_and_mark_text_in_range(
2539        &mut self,
2540        range: Option<Range<usize>>,
2541        new_text: &str,
2542        new_selected_range: Option<Range<usize>>,
2543        cx: &mut WindowContext,
2544        view_id: usize,
2545    );
2546    fn any_handle(&self, window_id: usize, view_id: usize, cx: &AppContext) -> AnyViewHandle {
2547        AnyViewHandle::new(
2548            window_id,
2549            view_id,
2550            self.as_any().type_id(),
2551            cx.ref_counts.clone(),
2552        )
2553    }
2554}
2555
2556impl<V> AnyView for V
2557where
2558    V: View,
2559{
2560    fn as_any(&self) -> &dyn Any {
2561        self
2562    }
2563
2564    fn as_any_mut(&mut self) -> &mut dyn Any {
2565        self
2566    }
2567
2568    fn release(&mut self, cx: &mut AppContext) {
2569        self.release(cx);
2570    }
2571
2572    fn app_will_quit(
2573        &mut self,
2574        cx: &mut AppContext,
2575    ) -> Option<Pin<Box<dyn 'static + Future<Output = ()>>>> {
2576        self.app_will_quit(cx)
2577    }
2578
2579    fn ui_name(&self) -> &'static str {
2580        V::ui_name()
2581    }
2582
2583    fn render(&mut self, cx: &mut WindowContext, view_id: usize) -> Box<dyn AnyRootElement> {
2584        let mut view_context = ViewContext::mutable(cx, view_id);
2585        let element = V::render(self, &mut view_context);
2586        let view = WeakViewHandle::new(cx.window_id, view_id);
2587        Box::new(RootElement::new(element, view))
2588    }
2589
2590    fn focus_in(&mut self, focused_id: usize, cx: &mut WindowContext, view_id: usize) {
2591        let mut cx = ViewContext::mutable(cx, view_id);
2592        let focused_view_handle: AnyViewHandle = if view_id == focused_id {
2593            cx.handle().into_any()
2594        } else {
2595            let focused_type = cx
2596                .views_metadata
2597                .get(&(cx.window_id, focused_id))
2598                .unwrap()
2599                .type_id;
2600            AnyViewHandle::new(
2601                cx.window_id,
2602                focused_id,
2603                focused_type,
2604                cx.ref_counts.clone(),
2605            )
2606        };
2607        View::focus_in(self, focused_view_handle, &mut cx);
2608    }
2609
2610    fn focus_out(&mut self, blurred_id: usize, cx: &mut WindowContext, view_id: usize) {
2611        let mut cx = ViewContext::mutable(cx, view_id);
2612        let blurred_view_handle: AnyViewHandle = if view_id == blurred_id {
2613            cx.handle().into_any()
2614        } else {
2615            let blurred_type = cx
2616                .views_metadata
2617                .get(&(cx.window_id, blurred_id))
2618                .unwrap()
2619                .type_id;
2620            AnyViewHandle::new(
2621                cx.window_id,
2622                blurred_id,
2623                blurred_type,
2624                cx.ref_counts.clone(),
2625            )
2626        };
2627        View::focus_out(self, blurred_view_handle, &mut cx);
2628    }
2629
2630    fn key_down(&mut self, event: &KeyDownEvent, cx: &mut WindowContext, view_id: usize) -> bool {
2631        let mut cx = ViewContext::mutable(cx, view_id);
2632        View::key_down(self, event, &mut cx)
2633    }
2634
2635    fn key_up(&mut self, event: &KeyUpEvent, cx: &mut WindowContext, view_id: usize) -> bool {
2636        let mut cx = ViewContext::mutable(cx, view_id);
2637        View::key_up(self, event, &mut cx)
2638    }
2639
2640    fn modifiers_changed(
2641        &mut self,
2642        event: &ModifiersChangedEvent,
2643        cx: &mut WindowContext,
2644        view_id: usize,
2645    ) -> bool {
2646        let mut cx = ViewContext::mutable(cx, view_id);
2647        View::modifiers_changed(self, event, &mut cx)
2648    }
2649
2650    fn update_keymap_context(&self, keymap: &mut KeymapContext, cx: &AppContext) {
2651        View::update_keymap_context(self, keymap, cx)
2652    }
2653
2654    fn debug_json(&self, cx: &WindowContext) -> serde_json::Value {
2655        View::debug_json(self, cx)
2656    }
2657
2658    fn text_for_range(&self, range: Range<usize>, cx: &WindowContext) -> Option<String> {
2659        View::text_for_range(self, range, cx)
2660    }
2661
2662    fn selected_text_range(&self, cx: &WindowContext) -> Option<Range<usize>> {
2663        View::selected_text_range(self, cx)
2664    }
2665
2666    fn marked_text_range(&self, cx: &WindowContext) -> Option<Range<usize>> {
2667        View::marked_text_range(self, cx)
2668    }
2669
2670    fn unmark_text(&mut self, cx: &mut WindowContext, view_id: usize) {
2671        let mut cx = ViewContext::mutable(cx, view_id);
2672        View::unmark_text(self, &mut cx)
2673    }
2674
2675    fn replace_text_in_range(
2676        &mut self,
2677        range: Option<Range<usize>>,
2678        text: &str,
2679        cx: &mut WindowContext,
2680        view_id: usize,
2681    ) {
2682        let mut cx = ViewContext::mutable(cx, view_id);
2683        View::replace_text_in_range(self, range, text, &mut cx)
2684    }
2685
2686    fn replace_and_mark_text_in_range(
2687        &mut self,
2688        range: Option<Range<usize>>,
2689        new_text: &str,
2690        new_selected_range: Option<Range<usize>>,
2691        cx: &mut WindowContext,
2692        view_id: usize,
2693    ) {
2694        let mut cx = ViewContext::mutable(cx, view_id);
2695        View::replace_and_mark_text_in_range(self, range, new_text, new_selected_range, &mut cx)
2696    }
2697}
2698
2699pub struct ModelContext<'a, T: ?Sized> {
2700    app: &'a mut AppContext,
2701    model_id: usize,
2702    model_type: PhantomData<T>,
2703    halt_stream: bool,
2704}
2705
2706impl<'a, T: Entity> ModelContext<'a, T> {
2707    fn new(app: &'a mut AppContext, model_id: usize) -> Self {
2708        Self {
2709            app,
2710            model_id,
2711            model_type: PhantomData,
2712            halt_stream: false,
2713        }
2714    }
2715
2716    pub fn background(&self) -> &Arc<executor::Background> {
2717        &self.app.background
2718    }
2719
2720    pub fn halt_stream(&mut self) {
2721        self.halt_stream = true;
2722    }
2723
2724    pub fn model_id(&self) -> usize {
2725        self.model_id
2726    }
2727
2728    pub fn add_model<S, F>(&mut self, build_model: F) -> ModelHandle<S>
2729    where
2730        S: Entity,
2731        F: FnOnce(&mut ModelContext<S>) -> S,
2732    {
2733        self.app.add_model(build_model)
2734    }
2735
2736    pub fn emit(&mut self, payload: T::Event) {
2737        self.app.pending_effects.push_back(Effect::Event {
2738            entity_id: self.model_id,
2739            payload: Box::new(payload),
2740        });
2741    }
2742
2743    pub fn notify(&mut self) {
2744        self.app.notify_model(self.model_id);
2745    }
2746
2747    pub fn subscribe<S: Entity, F>(
2748        &mut self,
2749        handle: &ModelHandle<S>,
2750        mut callback: F,
2751    ) -> Subscription
2752    where
2753        S::Event: 'static,
2754        F: 'static + FnMut(&mut T, ModelHandle<S>, &S::Event, &mut ModelContext<T>),
2755    {
2756        let subscriber = self.weak_handle();
2757        self.app
2758            .subscribe_internal(handle, move |emitter, event, cx| {
2759                if let Some(subscriber) = subscriber.upgrade(cx) {
2760                    subscriber.update(cx, |subscriber, cx| {
2761                        callback(subscriber, emitter, event, cx);
2762                    });
2763                    true
2764                } else {
2765                    false
2766                }
2767            })
2768    }
2769
2770    pub fn observe<S, F>(&mut self, handle: &ModelHandle<S>, mut callback: F) -> Subscription
2771    where
2772        S: Entity,
2773        F: 'static + FnMut(&mut T, ModelHandle<S>, &mut ModelContext<T>),
2774    {
2775        let observer = self.weak_handle();
2776        self.app.observe_internal(handle, move |observed, cx| {
2777            if let Some(observer) = observer.upgrade(cx) {
2778                observer.update(cx, |observer, cx| {
2779                    callback(observer, observed, cx);
2780                });
2781                true
2782            } else {
2783                false
2784            }
2785        })
2786    }
2787
2788    pub fn observe_global<G, F>(&mut self, mut callback: F) -> Subscription
2789    where
2790        G: Any,
2791        F: 'static + FnMut(&mut T, &mut ModelContext<T>),
2792    {
2793        let observer = self.weak_handle();
2794        self.app.observe_global::<G, _>(move |cx| {
2795            if let Some(observer) = observer.upgrade(cx) {
2796                observer.update(cx, |observer, cx| callback(observer, cx));
2797            }
2798        })
2799    }
2800
2801    pub fn observe_release<S, F>(
2802        &mut self,
2803        handle: &ModelHandle<S>,
2804        mut callback: F,
2805    ) -> Subscription
2806    where
2807        S: Entity,
2808        F: 'static + FnMut(&mut T, &S, &mut ModelContext<T>),
2809    {
2810        let observer = self.weak_handle();
2811        self.app.observe_release(handle, move |released, cx| {
2812            if let Some(observer) = observer.upgrade(cx) {
2813                observer.update(cx, |observer, cx| {
2814                    callback(observer, released, cx);
2815                });
2816            }
2817        })
2818    }
2819
2820    pub fn handle(&self) -> ModelHandle<T> {
2821        ModelHandle::new(self.model_id, &self.app.ref_counts)
2822    }
2823
2824    pub fn weak_handle(&self) -> WeakModelHandle<T> {
2825        WeakModelHandle::new(self.model_id)
2826    }
2827
2828    pub fn spawn<F, Fut, S>(&mut self, f: F) -> Task<S>
2829    where
2830        F: FnOnce(ModelHandle<T>, AsyncAppContext) -> Fut,
2831        Fut: 'static + Future<Output = S>,
2832        S: 'static,
2833    {
2834        let handle = self.handle();
2835        self.app.spawn(|cx| f(handle, cx))
2836    }
2837
2838    pub fn spawn_weak<F, Fut, S>(&mut self, f: F) -> Task<S>
2839    where
2840        F: FnOnce(WeakModelHandle<T>, AsyncAppContext) -> Fut,
2841        Fut: 'static + Future<Output = S>,
2842        S: 'static,
2843    {
2844        let handle = self.weak_handle();
2845        self.app.spawn(|cx| f(handle, cx))
2846    }
2847}
2848
2849impl<M> AsRef<AppContext> for ModelContext<'_, M> {
2850    fn as_ref(&self) -> &AppContext {
2851        &self.app
2852    }
2853}
2854
2855impl<M> AsMut<AppContext> for ModelContext<'_, M> {
2856    fn as_mut(&mut self) -> &mut AppContext {
2857        self.app
2858    }
2859}
2860
2861impl<M> BorrowAppContext for ModelContext<'_, M> {
2862    fn read_with<T, F: FnOnce(&AppContext) -> T>(&self, f: F) -> T {
2863        self.app.read_with(f)
2864    }
2865
2866    fn update<T, F: FnOnce(&mut AppContext) -> T>(&mut self, f: F) -> T {
2867        self.app.update(f)
2868    }
2869}
2870
2871impl<M> Deref for ModelContext<'_, M> {
2872    type Target = AppContext;
2873
2874    fn deref(&self) -> &Self::Target {
2875        self.app
2876    }
2877}
2878
2879impl<M> DerefMut for ModelContext<'_, M> {
2880    fn deref_mut(&mut self) -> &mut Self::Target {
2881        &mut self.app
2882    }
2883}
2884
2885pub struct ViewContext<'a, 'b, T: ?Sized> {
2886    window_context: Reference<'b, WindowContext<'a>>,
2887    view_id: usize,
2888    view_type: PhantomData<T>,
2889}
2890
2891impl<'a, 'b, T: View> Deref for ViewContext<'a, 'b, T> {
2892    type Target = WindowContext<'a>;
2893
2894    fn deref(&self) -> &Self::Target {
2895        &self.window_context
2896    }
2897}
2898
2899impl<T: View> DerefMut for ViewContext<'_, '_, T> {
2900    fn deref_mut(&mut self) -> &mut Self::Target {
2901        &mut self.window_context
2902    }
2903}
2904
2905impl<'a, 'b, V: View> ViewContext<'a, 'b, V> {
2906    pub(crate) fn mutable(window_context: &'b mut WindowContext<'a>, view_id: usize) -> Self {
2907        Self {
2908            window_context: Reference::Mutable(window_context),
2909            view_id,
2910            view_type: PhantomData,
2911        }
2912    }
2913
2914    pub(crate) fn immutable(window_context: &'b WindowContext<'a>, view_id: usize) -> Self {
2915        Self {
2916            window_context: Reference::Immutable(window_context),
2917            view_id,
2918            view_type: PhantomData,
2919        }
2920    }
2921
2922    pub fn window_context(&mut self) -> &mut WindowContext<'a> {
2923        &mut self.window_context
2924    }
2925
2926    pub fn handle(&self) -> ViewHandle<V> {
2927        ViewHandle::new(
2928            self.window_id,
2929            self.view_id,
2930            &self.window_context.ref_counts,
2931        )
2932    }
2933
2934    pub fn weak_handle(&self) -> WeakViewHandle<V> {
2935        WeakViewHandle::new(self.window_id, self.view_id)
2936    }
2937
2938    pub fn window_id(&self) -> usize {
2939        self.window_id
2940    }
2941
2942    pub fn view_id(&self) -> usize {
2943        self.view_id
2944    }
2945
2946    pub fn foreground(&self) -> &Rc<executor::Foreground> {
2947        self.window_context.foreground()
2948    }
2949
2950    pub fn background_executor(&self) -> &Arc<executor::Background> {
2951        &self.window_context.background
2952    }
2953
2954    pub fn platform(&self) -> &Arc<dyn Platform> {
2955        self.window_context.platform()
2956    }
2957
2958    pub fn prompt_for_paths(
2959        &self,
2960        options: PathPromptOptions,
2961    ) -> oneshot::Receiver<Option<Vec<PathBuf>>> {
2962        self.window_context.prompt_for_paths(options)
2963    }
2964
2965    pub fn prompt_for_new_path(&self, directory: &Path) -> oneshot::Receiver<Option<PathBuf>> {
2966        self.window_context.prompt_for_new_path(directory)
2967    }
2968
2969    pub fn reveal_path(&self, path: &Path) {
2970        self.window_context.reveal_path(path)
2971    }
2972
2973    pub fn focus(&mut self, handle: &AnyViewHandle) {
2974        self.window_context.focus(Some(handle.view_id));
2975    }
2976
2977    pub fn focus_self(&mut self) {
2978        let view_id = self.view_id;
2979        self.window_context.focus(Some(view_id));
2980    }
2981
2982    pub fn is_self_focused(&self) -> bool {
2983        self.window.focused_view_id == Some(self.view_id)
2984    }
2985
2986    pub fn focus_parent(&mut self) {
2987        let window_id = self.window_id;
2988        let view_id = self.view_id;
2989        self.pending_effects
2990            .push_back(Effect::Focus(FocusEffect::ViewParent {
2991                window_id,
2992                view_id,
2993                is_forced: false,
2994            }));
2995    }
2996
2997    pub fn blur(&mut self) {
2998        self.window_context.focus(None);
2999    }
3000
3001    pub fn on_window_should_close<F>(&mut self, mut callback: F)
3002    where
3003        F: 'static + FnMut(&mut V, &mut ViewContext<V>) -> bool,
3004    {
3005        let window_id = self.window_id;
3006        let view = self.weak_handle();
3007        self.pending_effects
3008            .push_back(Effect::WindowShouldCloseSubscription {
3009                window_id,
3010                callback: Box::new(move |cx| {
3011                    cx.update_window(window_id, |cx| {
3012                        if let Some(view) = view.upgrade(cx) {
3013                            view.update(cx, |view, cx| callback(view, cx))
3014                        } else {
3015                            true
3016                        }
3017                    })
3018                    .unwrap_or(true)
3019                }),
3020            });
3021    }
3022
3023    pub fn subscribe<E, H, F>(&mut self, handle: &H, mut callback: F) -> Subscription
3024    where
3025        E: Entity,
3026        E::Event: 'static,
3027        H: Handle<E>,
3028        F: 'static + FnMut(&mut V, H, &E::Event, &mut ViewContext<V>),
3029    {
3030        let subscriber = self.weak_handle();
3031        self.window_context
3032            .subscribe_internal(handle, move |emitter, event, cx| {
3033                if let Some(subscriber) = subscriber.upgrade(cx) {
3034                    subscriber.update(cx, |subscriber, cx| {
3035                        callback(subscriber, emitter, event, cx);
3036                    });
3037                    true
3038                } else {
3039                    false
3040                }
3041            })
3042    }
3043
3044    pub fn observe<E, F, H>(&mut self, handle: &H, mut callback: F) -> Subscription
3045    where
3046        E: Entity,
3047        H: Handle<E>,
3048        F: 'static + FnMut(&mut V, H, &mut ViewContext<V>),
3049    {
3050        let window_id = self.window_id;
3051        let observer = self.weak_handle();
3052        self.window_context
3053            .observe_internal(handle, move |observed, cx| {
3054                cx.update_window(window_id, |cx| {
3055                    if let Some(observer) = observer.upgrade(cx) {
3056                        observer.update(cx, |observer, cx| {
3057                            callback(observer, observed, cx);
3058                        });
3059                        true
3060                    } else {
3061                        false
3062                    }
3063                })
3064                .unwrap_or(false)
3065            })
3066    }
3067
3068    pub fn observe_global<G, F>(&mut self, mut callback: F) -> Subscription
3069    where
3070        G: Any,
3071        F: 'static + FnMut(&mut V, &mut ViewContext<V>),
3072    {
3073        let window_id = self.window_id;
3074        let observer = self.weak_handle();
3075        self.window_context.observe_global::<G, _>(move |cx| {
3076            cx.update_window(window_id, |cx| {
3077                if let Some(observer) = observer.upgrade(cx) {
3078                    observer.update(cx, |observer, cx| callback(observer, cx));
3079                }
3080            });
3081        })
3082    }
3083
3084    pub fn observe_focus<F, W>(&mut self, handle: &ViewHandle<W>, mut callback: F) -> Subscription
3085    where
3086        F: 'static + FnMut(&mut V, ViewHandle<W>, bool, &mut ViewContext<V>),
3087        W: View,
3088    {
3089        let observer = self.weak_handle();
3090        self.window_context
3091            .observe_focus(handle, move |observed, focused, cx| {
3092                if let Some(observer) = observer.upgrade(cx) {
3093                    observer.update(cx, |observer, cx| {
3094                        callback(observer, observed, focused, cx);
3095                    });
3096                    true
3097                } else {
3098                    false
3099                }
3100            })
3101    }
3102
3103    pub fn observe_release<E, F, H>(&mut self, handle: &H, mut callback: F) -> Subscription
3104    where
3105        E: Entity,
3106        H: Handle<E>,
3107        F: 'static + FnMut(&mut V, &E, &mut ViewContext<V>),
3108    {
3109        let window_id = self.window_id;
3110        let observer = self.weak_handle();
3111        self.window_context
3112            .observe_release(handle, move |released, cx| {
3113                cx.update_window(window_id, |cx| {
3114                    if let Some(observer) = observer.upgrade(cx) {
3115                        observer.update(cx, |observer, cx| {
3116                            callback(observer, released, cx);
3117                        });
3118                    }
3119                });
3120            })
3121    }
3122
3123    pub fn observe_actions<F>(&mut self, mut callback: F) -> Subscription
3124    where
3125        F: 'static + FnMut(&mut V, TypeId, &mut ViewContext<V>),
3126    {
3127        let window_id = self.window_id;
3128        let observer = self.weak_handle();
3129        self.window_context.observe_actions(move |action_id, cx| {
3130            cx.update_window(window_id, |cx| {
3131                if let Some(observer) = observer.upgrade(cx) {
3132                    observer.update(cx, |observer, cx| {
3133                        callback(observer, action_id, cx);
3134                    });
3135                }
3136            });
3137        })
3138    }
3139
3140    pub fn observe_window_activation<F>(&mut self, mut callback: F) -> Subscription
3141    where
3142        F: 'static + FnMut(&mut V, bool, &mut ViewContext<V>),
3143    {
3144        let observer = self.weak_handle();
3145        self.window_context
3146            .observe_window_activation(move |active, cx| {
3147                if let Some(observer) = observer.upgrade(cx) {
3148                    observer.update(cx, |observer, cx| {
3149                        callback(observer, active, cx);
3150                    });
3151                    true
3152                } else {
3153                    false
3154                }
3155            })
3156    }
3157
3158    pub fn observe_fullscreen<F>(&mut self, mut callback: F) -> Subscription
3159    where
3160        F: 'static + FnMut(&mut V, bool, &mut ViewContext<V>),
3161    {
3162        let observer = self.weak_handle();
3163        self.window_context.observe_fullscreen(move |active, cx| {
3164            if let Some(observer) = observer.upgrade(cx) {
3165                observer.update(cx, |observer, cx| {
3166                    callback(observer, active, cx);
3167                });
3168                true
3169            } else {
3170                false
3171            }
3172        })
3173    }
3174
3175    pub fn observe_keystrokes<F>(&mut self, mut callback: F) -> Subscription
3176    where
3177        F: 'static
3178            + FnMut(
3179                &mut V,
3180                &Keystroke,
3181                Option<&Box<dyn Action>>,
3182                &MatchResult,
3183                &mut ViewContext<V>,
3184            ) -> bool,
3185    {
3186        let observer = self.weak_handle();
3187        self.window_context
3188            .observe_keystrokes(move |keystroke, result, handled_by, cx| {
3189                if let Some(observer) = observer.upgrade(cx) {
3190                    observer.update(cx, |observer, cx| {
3191                        callback(observer, keystroke, handled_by, result, cx);
3192                    });
3193                    true
3194                } else {
3195                    false
3196                }
3197            })
3198    }
3199
3200    pub fn observe_window_bounds<F>(&mut self, mut callback: F) -> Subscription
3201    where
3202        F: 'static + FnMut(&mut V, WindowBounds, Uuid, &mut ViewContext<V>),
3203    {
3204        let observer = self.weak_handle();
3205        self.window_context
3206            .observe_window_bounds(move |bounds, display, cx| {
3207                if let Some(observer) = observer.upgrade(cx) {
3208                    observer.update(cx, |observer, cx| {
3209                        callback(observer, bounds, display, cx);
3210                    });
3211                    true
3212                } else {
3213                    false
3214                }
3215            })
3216    }
3217
3218    pub fn observe_active_labeled_tasks<F>(&mut self, mut callback: F) -> Subscription
3219    where
3220        F: 'static + FnMut(&mut V, &mut ViewContext<V>),
3221    {
3222        let window_id = self.window_id;
3223        let observer = self.weak_handle();
3224        self.window_context.observe_active_labeled_tasks(move |cx| {
3225            cx.update_window(window_id, |cx| {
3226                if let Some(observer) = observer.upgrade(cx) {
3227                    observer.update(cx, |observer, cx| {
3228                        callback(observer, cx);
3229                    });
3230                    true
3231                } else {
3232                    false
3233                }
3234            })
3235            .unwrap_or(false)
3236        })
3237    }
3238
3239    pub fn emit(&mut self, payload: V::Event) {
3240        self.window_context
3241            .pending_effects
3242            .push_back(Effect::Event {
3243                entity_id: self.view_id,
3244                payload: Box::new(payload),
3245            });
3246    }
3247
3248    pub fn notify(&mut self) {
3249        let window_id = self.window_id;
3250        let view_id = self.view_id;
3251        self.window_context.notify_view(window_id, view_id);
3252    }
3253
3254    pub fn defer(&mut self, callback: impl 'static + FnOnce(&mut V, &mut ViewContext<V>)) {
3255        let handle = self.handle();
3256        self.window_context
3257            .defer(move |cx| handle.update(cx, |view, cx| callback(view, cx)))
3258    }
3259
3260    pub fn after_window_update(
3261        &mut self,
3262        callback: impl 'static + FnOnce(&mut V, &mut ViewContext<V>),
3263    ) {
3264        let window_id = self.window_id;
3265        let handle = self.handle();
3266        self.window_context.after_window_update(move |cx| {
3267            cx.update_window(window_id, |cx| {
3268                handle.update(cx, |view, cx| {
3269                    callback(view, cx);
3270                })
3271            });
3272        })
3273    }
3274
3275    pub fn propagate_action(&mut self) {
3276        self.window_context.halt_action_dispatch = false;
3277    }
3278
3279    pub fn spawn_labeled<F, Fut, S>(&mut self, task_label: &'static str, f: F) -> Task<S>
3280    where
3281        F: FnOnce(WeakViewHandle<V>, AsyncAppContext) -> Fut,
3282        Fut: 'static + Future<Output = S>,
3283        S: 'static,
3284    {
3285        let handle = self.weak_handle();
3286        self.window_context
3287            .spawn_labeled(task_label, |cx| f(handle, cx))
3288    }
3289
3290    pub fn spawn<F, Fut, S>(&mut self, f: F) -> Task<S>
3291    where
3292        F: FnOnce(WeakViewHandle<V>, AsyncAppContext) -> Fut,
3293        Fut: 'static + Future<Output = S>,
3294        S: 'static,
3295    {
3296        let handle = self.weak_handle();
3297        self.window_context.spawn(|cx| f(handle, cx))
3298    }
3299
3300    pub fn mouse_state<Tag: 'static>(&self, region_id: usize) -> MouseState {
3301        let region_id = MouseRegionId::new::<Tag>(self.view_id, region_id);
3302        MouseState {
3303            hovered: self.window.hovered_region_ids.contains(&region_id),
3304            clicked: if let Some((clicked_region_id, button)) = self.window.clicked_region {
3305                if region_id == clicked_region_id {
3306                    Some(button)
3307                } else {
3308                    None
3309                }
3310            } else {
3311                None
3312            },
3313            accessed_hovered: false,
3314            accessed_clicked: false,
3315        }
3316    }
3317
3318    pub fn element_state<Tag: 'static, T: 'static>(
3319        &mut self,
3320        element_id: usize,
3321        initial: T,
3322    ) -> ElementStateHandle<T> {
3323        let id = ElementStateId {
3324            view_id: self.view_id(),
3325            element_id,
3326            tag: TypeId::of::<Tag>(),
3327        };
3328        self.element_states
3329            .entry(id)
3330            .or_insert_with(|| Box::new(initial));
3331        ElementStateHandle::new(id, self.frame_count, &self.ref_counts)
3332    }
3333
3334    pub fn default_element_state<Tag: 'static, T: 'static + Default>(
3335        &mut self,
3336        element_id: usize,
3337    ) -> ElementStateHandle<T> {
3338        self.element_state::<Tag, T>(element_id, T::default())
3339    }
3340}
3341
3342impl<V> BorrowAppContext for ViewContext<'_, '_, V> {
3343    fn read_with<T, F: FnOnce(&AppContext) -> T>(&self, f: F) -> T {
3344        BorrowAppContext::read_with(&*self.window_context, f)
3345    }
3346
3347    fn update<T, F: FnOnce(&mut AppContext) -> T>(&mut self, f: F) -> T {
3348        BorrowAppContext::update(&mut *self.window_context, f)
3349    }
3350}
3351
3352impl<V> BorrowWindowContext for ViewContext<'_, '_, V> {
3353    fn read_with<T, F: FnOnce(&WindowContext) -> T>(&self, window_id: usize, f: F) -> T {
3354        BorrowWindowContext::read_with(&*self.window_context, window_id, f)
3355    }
3356
3357    fn update<T, F: FnOnce(&mut WindowContext) -> T>(&mut self, window_id: usize, f: F) -> T {
3358        BorrowWindowContext::update(&mut *self.window_context, window_id, f)
3359    }
3360}
3361
3362pub struct LayoutContext<'a, 'b, 'c, V: View> {
3363    view_context: &'c mut ViewContext<'a, 'b, V>,
3364    new_parents: &'c mut HashMap<usize, usize>,
3365    views_to_notify_if_ancestors_change: &'c mut HashMap<usize, SmallVec<[usize; 2]>>,
3366    pub refreshing: bool,
3367}
3368
3369impl<'a, 'b, 'c, V: View> LayoutContext<'a, 'b, 'c, V> {
3370    pub fn new(
3371        view_context: &'c mut ViewContext<'a, 'b, V>,
3372        new_parents: &'c mut HashMap<usize, usize>,
3373        views_to_notify_if_ancestors_change: &'c mut HashMap<usize, SmallVec<[usize; 2]>>,
3374        refreshing: bool,
3375    ) -> Self {
3376        Self {
3377            view_context,
3378            new_parents,
3379            views_to_notify_if_ancestors_change,
3380            refreshing,
3381        }
3382    }
3383
3384    pub fn view_context(&mut self) -> &mut ViewContext<'a, 'b, V> {
3385        self.view_context
3386    }
3387
3388    /// Return keystrokes that would dispatch the given action on the given view.
3389    pub(crate) fn keystrokes_for_action(
3390        &mut self,
3391        view_id: usize,
3392        action: &dyn Action,
3393    ) -> Option<SmallVec<[Keystroke; 2]>> {
3394        self.notify_if_view_ancestors_change(view_id);
3395
3396        let window_id = self.window_id;
3397        let mut contexts = Vec::new();
3398        let mut handler_depth = None;
3399        for (i, view_id) in self.ancestors(view_id).enumerate() {
3400            if let Some(view_metadata) = self.views_metadata.get(&(window_id, view_id)) {
3401                if let Some(actions) = self.actions.get(&view_metadata.type_id) {
3402                    if actions.contains_key(&action.id()) {
3403                        handler_depth = Some(i);
3404                    }
3405                }
3406                contexts.push(view_metadata.keymap_context.clone());
3407            }
3408        }
3409
3410        if self.global_actions.contains_key(&action.id()) {
3411            handler_depth = Some(contexts.len())
3412        }
3413
3414        let action_contexts = if let Some(depth) = handler_depth {
3415            &contexts[depth..]
3416        } else {
3417            &contexts
3418        };
3419
3420        self.keystroke_matcher
3421            .keystrokes_for_action(action, action_contexts)
3422    }
3423
3424    fn notify_if_view_ancestors_change(&mut self, view_id: usize) {
3425        let self_view_id = self.view_id;
3426        self.views_to_notify_if_ancestors_change
3427            .entry(view_id)
3428            .or_default()
3429            .push(self_view_id);
3430    }
3431}
3432
3433impl<'a, 'b, 'c, V: View> Deref for LayoutContext<'a, 'b, 'c, V> {
3434    type Target = ViewContext<'a, 'b, V>;
3435
3436    fn deref(&self) -> &Self::Target {
3437        &self.view_context
3438    }
3439}
3440
3441impl<V: View> DerefMut for LayoutContext<'_, '_, '_, V> {
3442    fn deref_mut(&mut self) -> &mut Self::Target {
3443        &mut self.view_context
3444    }
3445}
3446
3447impl<V: View> BorrowAppContext for LayoutContext<'_, '_, '_, V> {
3448    fn read_with<T, F: FnOnce(&AppContext) -> T>(&self, f: F) -> T {
3449        BorrowAppContext::read_with(&*self.view_context, f)
3450    }
3451
3452    fn update<T, F: FnOnce(&mut AppContext) -> T>(&mut self, f: F) -> T {
3453        BorrowAppContext::update(&mut *self.view_context, f)
3454    }
3455}
3456
3457impl<V: View> BorrowWindowContext for LayoutContext<'_, '_, '_, V> {
3458    fn read_with<T, F: FnOnce(&WindowContext) -> T>(&self, window_id: usize, f: F) -> T {
3459        BorrowWindowContext::read_with(&*self.view_context, window_id, f)
3460    }
3461
3462    fn update<T, F: FnOnce(&mut WindowContext) -> T>(&mut self, window_id: usize, f: F) -> T {
3463        BorrowWindowContext::update(&mut *self.view_context, window_id, f)
3464    }
3465}
3466
3467pub struct EventContext<'a, 'b, 'c, V: View> {
3468    view_context: &'c mut ViewContext<'a, 'b, V>,
3469    pub(crate) handled: bool,
3470}
3471
3472impl<'a, 'b, 'c, V: View> EventContext<'a, 'b, 'c, V> {
3473    pub(crate) fn new(view_context: &'c mut ViewContext<'a, 'b, V>) -> Self {
3474        EventContext {
3475            view_context,
3476            handled: true,
3477        }
3478    }
3479
3480    pub fn propagate_event(&mut self) {
3481        self.handled = false;
3482    }
3483}
3484
3485impl<'a, 'b, 'c, V: View> Deref for EventContext<'a, 'b, 'c, V> {
3486    type Target = ViewContext<'a, 'b, V>;
3487
3488    fn deref(&self) -> &Self::Target {
3489        &self.view_context
3490    }
3491}
3492
3493impl<V: View> DerefMut for EventContext<'_, '_, '_, V> {
3494    fn deref_mut(&mut self) -> &mut Self::Target {
3495        &mut self.view_context
3496    }
3497}
3498
3499impl<V: View> BorrowAppContext for EventContext<'_, '_, '_, V> {
3500    fn read_with<T, F: FnOnce(&AppContext) -> T>(&self, f: F) -> T {
3501        BorrowAppContext::read_with(&*self.view_context, f)
3502    }
3503
3504    fn update<T, F: FnOnce(&mut AppContext) -> T>(&mut self, f: F) -> T {
3505        BorrowAppContext::update(&mut *self.view_context, f)
3506    }
3507}
3508
3509impl<V: View> BorrowWindowContext for EventContext<'_, '_, '_, V> {
3510    fn read_with<T, F: FnOnce(&WindowContext) -> T>(&self, window_id: usize, f: F) -> T {
3511        BorrowWindowContext::read_with(&*self.view_context, window_id, f)
3512    }
3513
3514    fn update<T, F: FnOnce(&mut WindowContext) -> T>(&mut self, window_id: usize, f: F) -> T {
3515        BorrowWindowContext::update(&mut *self.view_context, window_id, f)
3516    }
3517}
3518
3519pub(crate) enum Reference<'a, T> {
3520    Immutable(&'a T),
3521    Mutable(&'a mut T),
3522}
3523
3524impl<'a, T> Deref for Reference<'a, T> {
3525    type Target = T;
3526
3527    fn deref(&self) -> &Self::Target {
3528        match self {
3529            Reference::Immutable(target) => target,
3530            Reference::Mutable(target) => target,
3531        }
3532    }
3533}
3534
3535impl<'a, T> DerefMut for Reference<'a, T> {
3536    fn deref_mut(&mut self) -> &mut Self::Target {
3537        match self {
3538            Reference::Immutable(_) => {
3539                panic!("cannot mutably deref an immutable reference. this is a bug in GPUI.");
3540            }
3541            Reference::Mutable(target) => target,
3542        }
3543    }
3544}
3545
3546#[derive(Debug, Clone, Default)]
3547pub struct MouseState {
3548    pub(crate) hovered: bool,
3549    pub(crate) clicked: Option<MouseButton>,
3550    pub(crate) accessed_hovered: bool,
3551    pub(crate) accessed_clicked: bool,
3552}
3553
3554impl MouseState {
3555    pub fn hovered(&mut self) -> bool {
3556        self.accessed_hovered = true;
3557        self.hovered
3558    }
3559
3560    pub fn clicked(&mut self) -> Option<MouseButton> {
3561        self.accessed_clicked = true;
3562        self.clicked
3563    }
3564
3565    pub fn accessed_hovered(&self) -> bool {
3566        self.accessed_hovered
3567    }
3568
3569    pub fn accessed_clicked(&self) -> bool {
3570        self.accessed_clicked
3571    }
3572}
3573
3574pub trait Handle<T> {
3575    type Weak: 'static;
3576    fn id(&self) -> usize;
3577    fn location(&self) -> EntityLocation;
3578    fn downgrade(&self) -> Self::Weak;
3579    fn upgrade_from(weak: &Self::Weak, cx: &AppContext) -> Option<Self>
3580    where
3581        Self: Sized;
3582}
3583
3584pub trait WeakHandle {
3585    fn id(&self) -> usize;
3586}
3587
3588#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash)]
3589pub enum EntityLocation {
3590    Model(usize),
3591    View(usize, usize),
3592}
3593
3594pub struct ModelHandle<T: Entity> {
3595    any_handle: AnyModelHandle,
3596    model_type: PhantomData<T>,
3597}
3598
3599impl<T: Entity> Deref for ModelHandle<T> {
3600    type Target = AnyModelHandle;
3601
3602    fn deref(&self) -> &Self::Target {
3603        &self.any_handle
3604    }
3605}
3606
3607impl<T: Entity> ModelHandle<T> {
3608    fn new(model_id: usize, ref_counts: &Arc<Mutex<RefCounts>>) -> Self {
3609        Self {
3610            any_handle: AnyModelHandle::new(model_id, TypeId::of::<T>(), ref_counts.clone()),
3611            model_type: PhantomData,
3612        }
3613    }
3614
3615    pub fn downgrade(&self) -> WeakModelHandle<T> {
3616        WeakModelHandle::new(self.model_id)
3617    }
3618
3619    pub fn id(&self) -> usize {
3620        self.model_id
3621    }
3622
3623    pub fn read<'a>(&self, cx: &'a AppContext) -> &'a T {
3624        cx.read_model(self)
3625    }
3626
3627    pub fn read_with<C, F, S>(&self, cx: &C, read: F) -> S
3628    where
3629        C: BorrowAppContext,
3630        F: FnOnce(&T, &AppContext) -> S,
3631    {
3632        cx.read_with(|cx| read(self.read(cx), cx))
3633    }
3634
3635    pub fn update<C, F, S>(&self, cx: &mut C, update: F) -> S
3636    where
3637        C: BorrowAppContext,
3638        F: FnOnce(&mut T, &mut ModelContext<T>) -> S,
3639    {
3640        let mut update = Some(update);
3641        cx.update(|cx| {
3642            cx.update_model(self, &mut |model, cx| {
3643                let update = update.take().unwrap();
3644                update(model, cx)
3645            })
3646        })
3647    }
3648}
3649
3650impl<T: Entity> Clone for ModelHandle<T> {
3651    fn clone(&self) -> Self {
3652        Self::new(self.model_id, &self.ref_counts)
3653    }
3654}
3655
3656impl<T: Entity> PartialEq for ModelHandle<T> {
3657    fn eq(&self, other: &Self) -> bool {
3658        self.model_id == other.model_id
3659    }
3660}
3661
3662impl<T: Entity> Eq for ModelHandle<T> {}
3663
3664impl<T: Entity> PartialEq<WeakModelHandle<T>> for ModelHandle<T> {
3665    fn eq(&self, other: &WeakModelHandle<T>) -> bool {
3666        self.model_id == other.model_id
3667    }
3668}
3669
3670impl<T: Entity> Hash for ModelHandle<T> {
3671    fn hash<H: Hasher>(&self, state: &mut H) {
3672        self.model_id.hash(state);
3673    }
3674}
3675
3676impl<T: Entity> std::borrow::Borrow<usize> for ModelHandle<T> {
3677    fn borrow(&self) -> &usize {
3678        &self.model_id
3679    }
3680}
3681
3682impl<T: Entity> Debug for ModelHandle<T> {
3683    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
3684        f.debug_tuple(&format!("ModelHandle<{}>", type_name::<T>()))
3685            .field(&self.model_id)
3686            .finish()
3687    }
3688}
3689
3690unsafe impl<T: Entity> Send for ModelHandle<T> {}
3691unsafe impl<T: Entity> Sync for ModelHandle<T> {}
3692
3693impl<T: Entity> Handle<T> for ModelHandle<T> {
3694    type Weak = WeakModelHandle<T>;
3695
3696    fn id(&self) -> usize {
3697        self.model_id
3698    }
3699
3700    fn location(&self) -> EntityLocation {
3701        EntityLocation::Model(self.model_id)
3702    }
3703
3704    fn downgrade(&self) -> Self::Weak {
3705        self.downgrade()
3706    }
3707
3708    fn upgrade_from(weak: &Self::Weak, cx: &AppContext) -> Option<Self>
3709    where
3710        Self: Sized,
3711    {
3712        weak.upgrade(cx)
3713    }
3714}
3715
3716pub struct WeakModelHandle<T> {
3717    any_handle: AnyWeakModelHandle,
3718    model_type: PhantomData<T>,
3719}
3720
3721impl<T> WeakModelHandle<T> {
3722    pub fn into_any(self) -> AnyWeakModelHandle {
3723        self.any_handle
3724    }
3725}
3726
3727impl<T> Deref for WeakModelHandle<T> {
3728    type Target = AnyWeakModelHandle;
3729
3730    fn deref(&self) -> &Self::Target {
3731        &self.any_handle
3732    }
3733}
3734
3735impl<T> WeakHandle for WeakModelHandle<T> {
3736    fn id(&self) -> usize {
3737        self.model_id
3738    }
3739}
3740
3741unsafe impl<T> Send for WeakModelHandle<T> {}
3742unsafe impl<T> Sync for WeakModelHandle<T> {}
3743
3744impl<T: Entity> WeakModelHandle<T> {
3745    fn new(model_id: usize) -> Self {
3746        Self {
3747            any_handle: AnyWeakModelHandle {
3748                model_id,
3749                model_type: TypeId::of::<T>(),
3750            },
3751            model_type: PhantomData,
3752        }
3753    }
3754
3755    pub fn id(&self) -> usize {
3756        self.model_id
3757    }
3758
3759    pub fn is_upgradable(&self, cx: &impl BorrowAppContext) -> bool {
3760        cx.read_with(|cx| cx.model_handle_is_upgradable(self))
3761    }
3762
3763    pub fn upgrade(&self, cx: &impl BorrowAppContext) -> Option<ModelHandle<T>> {
3764        cx.read_with(|cx| cx.upgrade_model_handle(self))
3765    }
3766}
3767
3768impl<T> Hash for WeakModelHandle<T> {
3769    fn hash<H: Hasher>(&self, state: &mut H) {
3770        self.model_id.hash(state)
3771    }
3772}
3773
3774impl<T> PartialEq for WeakModelHandle<T> {
3775    fn eq(&self, other: &Self) -> bool {
3776        self.model_id == other.model_id
3777    }
3778}
3779
3780impl<T> Eq for WeakModelHandle<T> {}
3781
3782impl<T: Entity> PartialEq<ModelHandle<T>> for WeakModelHandle<T> {
3783    fn eq(&self, other: &ModelHandle<T>) -> bool {
3784        self.model_id == other.model_id
3785    }
3786}
3787
3788impl<T> Clone for WeakModelHandle<T> {
3789    fn clone(&self) -> Self {
3790        Self {
3791            any_handle: self.any_handle.clone(),
3792            model_type: PhantomData,
3793        }
3794    }
3795}
3796
3797impl<T> Copy for WeakModelHandle<T> {}
3798
3799#[repr(transparent)]
3800pub struct ViewHandle<T> {
3801    any_handle: AnyViewHandle,
3802    view_type: PhantomData<T>,
3803}
3804
3805impl<T> Deref for ViewHandle<T> {
3806    type Target = AnyViewHandle;
3807
3808    fn deref(&self) -> &Self::Target {
3809        &self.any_handle
3810    }
3811}
3812
3813impl<T: View> ViewHandle<T> {
3814    fn new(window_id: usize, view_id: usize, ref_counts: &Arc<Mutex<RefCounts>>) -> Self {
3815        Self {
3816            any_handle: AnyViewHandle::new(
3817                window_id,
3818                view_id,
3819                TypeId::of::<T>(),
3820                ref_counts.clone(),
3821            ),
3822            view_type: PhantomData,
3823        }
3824    }
3825
3826    pub fn downgrade(&self) -> WeakViewHandle<T> {
3827        WeakViewHandle::new(self.window_id, self.view_id)
3828    }
3829
3830    pub fn into_any(self) -> AnyViewHandle {
3831        self.any_handle
3832    }
3833
3834    pub fn window_id(&self) -> usize {
3835        self.window_id
3836    }
3837
3838    pub fn id(&self) -> usize {
3839        self.view_id
3840    }
3841
3842    pub fn read<'a>(&self, cx: &'a AppContext) -> &'a T {
3843        cx.read_view(self)
3844    }
3845
3846    pub fn read_with<C, F, S>(&self, cx: &C, read: F) -> S
3847    where
3848        C: BorrowWindowContext,
3849        F: FnOnce(&T, &ViewContext<T>) -> S,
3850    {
3851        cx.read_with(self.window_id, |cx| {
3852            let cx = ViewContext::immutable(cx, self.view_id);
3853            read(cx.read_view(self), &cx)
3854        })
3855    }
3856
3857    pub fn update<C, F, S>(&self, cx: &mut C, update: F) -> S
3858    where
3859        C: BorrowWindowContext,
3860        F: FnOnce(&mut T, &mut ViewContext<T>) -> S,
3861    {
3862        let mut update = Some(update);
3863
3864        cx.update(self.window_id, |cx| {
3865            cx.update_view(self, &mut |view, cx| {
3866                let update = update.take().unwrap();
3867                update(view, cx)
3868            })
3869        })
3870    }
3871
3872    pub fn is_focused(&self, cx: &WindowContext) -> bool {
3873        cx.focused_view_id() == Some(self.view_id)
3874    }
3875}
3876
3877impl<T: View> Clone for ViewHandle<T> {
3878    fn clone(&self) -> Self {
3879        ViewHandle::new(self.window_id, self.view_id, &self.ref_counts)
3880    }
3881}
3882
3883impl<T> PartialEq for ViewHandle<T> {
3884    fn eq(&self, other: &Self) -> bool {
3885        self.window_id == other.window_id && self.view_id == other.view_id
3886    }
3887}
3888
3889impl<T> PartialEq<AnyViewHandle> for ViewHandle<T> {
3890    fn eq(&self, other: &AnyViewHandle) -> bool {
3891        self.window_id == other.window_id && self.view_id == other.view_id
3892    }
3893}
3894
3895impl<T> PartialEq<WeakViewHandle<T>> for ViewHandle<T> {
3896    fn eq(&self, other: &WeakViewHandle<T>) -> bool {
3897        self.window_id == other.window_id && self.view_id == other.view_id
3898    }
3899}
3900
3901impl<T> PartialEq<ViewHandle<T>> for WeakViewHandle<T> {
3902    fn eq(&self, other: &ViewHandle<T>) -> bool {
3903        self.window_id == other.window_id && self.view_id == other.view_id
3904    }
3905}
3906
3907impl<T> Eq for ViewHandle<T> {}
3908
3909impl<T> Hash for ViewHandle<T> {
3910    fn hash<H: Hasher>(&self, state: &mut H) {
3911        self.window_id.hash(state);
3912        self.view_id.hash(state);
3913    }
3914}
3915
3916impl<T> Debug for ViewHandle<T> {
3917    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
3918        f.debug_struct(&format!("ViewHandle<{}>", type_name::<T>()))
3919            .field("window_id", &self.window_id)
3920            .field("view_id", &self.view_id)
3921            .finish()
3922    }
3923}
3924
3925impl<T: View> Handle<T> for ViewHandle<T> {
3926    type Weak = WeakViewHandle<T>;
3927
3928    fn id(&self) -> usize {
3929        self.view_id
3930    }
3931
3932    fn location(&self) -> EntityLocation {
3933        EntityLocation::View(self.window_id, self.view_id)
3934    }
3935
3936    fn downgrade(&self) -> Self::Weak {
3937        self.downgrade()
3938    }
3939
3940    fn upgrade_from(weak: &Self::Weak, cx: &AppContext) -> Option<Self>
3941    where
3942        Self: Sized,
3943    {
3944        weak.upgrade(cx)
3945    }
3946}
3947
3948pub struct AnyViewHandle {
3949    window_id: usize,
3950    view_id: usize,
3951    view_type: TypeId,
3952    ref_counts: Arc<Mutex<RefCounts>>,
3953
3954    #[cfg(any(test, feature = "test-support"))]
3955    handle_id: usize,
3956}
3957
3958impl AnyViewHandle {
3959    fn new(
3960        window_id: usize,
3961        view_id: usize,
3962        view_type: TypeId,
3963        ref_counts: Arc<Mutex<RefCounts>>,
3964    ) -> Self {
3965        ref_counts.lock().inc_view(window_id, view_id);
3966
3967        #[cfg(any(test, feature = "test-support"))]
3968        let handle_id = ref_counts
3969            .lock()
3970            .leak_detector
3971            .lock()
3972            .handle_created(None, view_id);
3973
3974        Self {
3975            window_id,
3976            view_id,
3977            view_type,
3978            ref_counts,
3979            #[cfg(any(test, feature = "test-support"))]
3980            handle_id,
3981        }
3982    }
3983
3984    pub fn window_id(&self) -> usize {
3985        self.window_id
3986    }
3987
3988    pub fn id(&self) -> usize {
3989        self.view_id
3990    }
3991
3992    pub fn is<T: 'static>(&self) -> bool {
3993        TypeId::of::<T>() == self.view_type
3994    }
3995
3996    pub fn downcast<T: View>(self) -> Option<ViewHandle<T>> {
3997        if self.is::<T>() {
3998            Some(ViewHandle {
3999                any_handle: self,
4000                view_type: PhantomData,
4001            })
4002        } else {
4003            None
4004        }
4005    }
4006
4007    pub fn downcast_ref<T: View>(&self) -> Option<&ViewHandle<T>> {
4008        if self.is::<T>() {
4009            Some(unsafe { mem::transmute(self) })
4010        } else {
4011            None
4012        }
4013    }
4014
4015    pub fn downgrade(&self) -> AnyWeakViewHandle {
4016        AnyWeakViewHandle {
4017            window_id: self.window_id,
4018            view_id: self.view_id,
4019            view_type: self.view_type,
4020        }
4021    }
4022
4023    pub fn view_type(&self) -> TypeId {
4024        self.view_type
4025    }
4026
4027    pub fn debug_json<'a, 'b>(&self, cx: &'b WindowContext<'a>) -> serde_json::Value {
4028        cx.views
4029            .get(&(self.window_id, self.view_id))
4030            .map_or_else(|| serde_json::Value::Null, |view| view.debug_json(cx))
4031    }
4032}
4033
4034impl Clone for AnyViewHandle {
4035    fn clone(&self) -> Self {
4036        Self::new(
4037            self.window_id,
4038            self.view_id,
4039            self.view_type,
4040            self.ref_counts.clone(),
4041        )
4042    }
4043}
4044
4045impl PartialEq for AnyViewHandle {
4046    fn eq(&self, other: &Self) -> bool {
4047        self.window_id == other.window_id && self.view_id == other.view_id
4048    }
4049}
4050
4051impl<T> PartialEq<ViewHandle<T>> for AnyViewHandle {
4052    fn eq(&self, other: &ViewHandle<T>) -> bool {
4053        self.window_id == other.window_id && self.view_id == other.view_id
4054    }
4055}
4056
4057impl Drop for AnyViewHandle {
4058    fn drop(&mut self) {
4059        self.ref_counts
4060            .lock()
4061            .dec_view(self.window_id, self.view_id);
4062        #[cfg(any(test, feature = "test-support"))]
4063        self.ref_counts
4064            .lock()
4065            .leak_detector
4066            .lock()
4067            .handle_dropped(self.view_id, self.handle_id);
4068    }
4069}
4070
4071impl Debug for AnyViewHandle {
4072    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
4073        f.debug_struct("AnyViewHandle")
4074            .field("window_id", &self.window_id)
4075            .field("view_id", &self.view_id)
4076            .finish()
4077    }
4078}
4079
4080pub struct AnyModelHandle {
4081    model_id: usize,
4082    model_type: TypeId,
4083    ref_counts: Arc<Mutex<RefCounts>>,
4084
4085    #[cfg(any(test, feature = "test-support"))]
4086    handle_id: usize,
4087}
4088
4089impl AnyModelHandle {
4090    fn new(model_id: usize, model_type: TypeId, ref_counts: Arc<Mutex<RefCounts>>) -> Self {
4091        ref_counts.lock().inc_model(model_id);
4092
4093        #[cfg(any(test, feature = "test-support"))]
4094        let handle_id = ref_counts
4095            .lock()
4096            .leak_detector
4097            .lock()
4098            .handle_created(None, model_id);
4099
4100        Self {
4101            model_id,
4102            model_type,
4103            ref_counts,
4104
4105            #[cfg(any(test, feature = "test-support"))]
4106            handle_id,
4107        }
4108    }
4109
4110    pub fn downcast<T: Entity>(self) -> Option<ModelHandle<T>> {
4111        if self.is::<T>() {
4112            Some(ModelHandle {
4113                any_handle: self,
4114                model_type: PhantomData,
4115            })
4116        } else {
4117            None
4118        }
4119    }
4120
4121    pub fn downgrade(&self) -> AnyWeakModelHandle {
4122        AnyWeakModelHandle {
4123            model_id: self.model_id,
4124            model_type: self.model_type,
4125        }
4126    }
4127
4128    pub fn is<T: Entity>(&self) -> bool {
4129        self.model_type == TypeId::of::<T>()
4130    }
4131
4132    pub fn model_type(&self) -> TypeId {
4133        self.model_type
4134    }
4135}
4136
4137impl Clone for AnyModelHandle {
4138    fn clone(&self) -> Self {
4139        Self::new(self.model_id, self.model_type, self.ref_counts.clone())
4140    }
4141}
4142
4143impl Drop for AnyModelHandle {
4144    fn drop(&mut self) {
4145        let mut ref_counts = self.ref_counts.lock();
4146        ref_counts.dec_model(self.model_id);
4147
4148        #[cfg(any(test, feature = "test-support"))]
4149        ref_counts
4150            .leak_detector
4151            .lock()
4152            .handle_dropped(self.model_id, self.handle_id);
4153    }
4154}
4155
4156#[derive(Hash, PartialEq, Eq, Debug, Clone, Copy)]
4157pub struct AnyWeakModelHandle {
4158    model_id: usize,
4159    model_type: TypeId,
4160}
4161
4162impl AnyWeakModelHandle {
4163    pub fn upgrade(&self, cx: &impl BorrowAppContext) -> Option<AnyModelHandle> {
4164        cx.read_with(|cx| cx.upgrade_any_model_handle(self))
4165    }
4166
4167    pub fn model_type(&self) -> TypeId {
4168        self.model_type
4169    }
4170
4171    fn is<T: 'static>(&self) -> bool {
4172        TypeId::of::<T>() == self.model_type
4173    }
4174
4175    pub fn downcast<T: Entity>(self) -> Option<WeakModelHandle<T>> {
4176        if self.is::<T>() {
4177            let result = Some(WeakModelHandle {
4178                any_handle: self,
4179                model_type: PhantomData,
4180            });
4181
4182            result
4183        } else {
4184            None
4185        }
4186    }
4187}
4188
4189#[derive(Copy)]
4190pub struct WeakViewHandle<T> {
4191    any_handle: AnyWeakViewHandle,
4192    view_type: PhantomData<T>,
4193}
4194
4195impl<T> Debug for WeakViewHandle<T> {
4196    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
4197        f.debug_struct(&format!("WeakViewHandle<{}>", type_name::<T>()))
4198            .field("any_handle", &self.any_handle)
4199            .finish()
4200    }
4201}
4202
4203impl<T> WeakHandle for WeakViewHandle<T> {
4204    fn id(&self) -> usize {
4205        self.view_id
4206    }
4207}
4208
4209impl<V: View> WeakViewHandle<V> {
4210    fn new(window_id: usize, view_id: usize) -> Self {
4211        Self {
4212            any_handle: AnyWeakViewHandle {
4213                window_id,
4214                view_id,
4215                view_type: TypeId::of::<V>(),
4216            },
4217            view_type: PhantomData,
4218        }
4219    }
4220
4221    pub fn id(&self) -> usize {
4222        self.view_id
4223    }
4224
4225    pub fn window_id(&self) -> usize {
4226        self.window_id
4227    }
4228
4229    pub fn into_any(self) -> AnyWeakViewHandle {
4230        self.any_handle
4231    }
4232
4233    pub fn upgrade(&self, cx: &impl BorrowAppContext) -> Option<ViewHandle<V>> {
4234        cx.read_with(|cx| cx.upgrade_view_handle(self))
4235    }
4236
4237    pub fn read_with<T>(
4238        &self,
4239        cx: &AsyncAppContext,
4240        read: impl FnOnce(&V, &ViewContext<V>) -> T,
4241    ) -> Result<T> {
4242        cx.read(|cx| {
4243            let handle = cx
4244                .upgrade_view_handle(self)
4245                .ok_or_else(|| anyhow!("view {} was dropped", V::ui_name()))?;
4246            cx.read_window(self.window_id, |cx| handle.read_with(cx, read))
4247                .ok_or_else(|| anyhow!("window was removed"))
4248        })
4249    }
4250
4251    pub fn update<T>(
4252        &self,
4253        cx: &mut AsyncAppContext,
4254        update: impl FnOnce(&mut V, &mut ViewContext<V>) -> T,
4255    ) -> Result<T> {
4256        cx.update(|cx| {
4257            let handle = cx
4258                .upgrade_view_handle(self)
4259                .ok_or_else(|| anyhow!("view {} was dropped", V::ui_name()))?;
4260            cx.update_window(self.window_id, |cx| handle.update(cx, update))
4261                .ok_or_else(|| anyhow!("window was removed"))
4262        })
4263    }
4264}
4265
4266impl<T> Deref for WeakViewHandle<T> {
4267    type Target = AnyWeakViewHandle;
4268
4269    fn deref(&self) -> &Self::Target {
4270        &self.any_handle
4271    }
4272}
4273
4274impl<T> Clone for WeakViewHandle<T> {
4275    fn clone(&self) -> Self {
4276        Self {
4277            any_handle: self.any_handle.clone(),
4278            view_type: PhantomData,
4279        }
4280    }
4281}
4282
4283impl<T> PartialEq for WeakViewHandle<T> {
4284    fn eq(&self, other: &Self) -> bool {
4285        self.window_id == other.window_id && self.view_id == other.view_id
4286    }
4287}
4288
4289impl<T> Eq for WeakViewHandle<T> {}
4290
4291impl<T> Hash for WeakViewHandle<T> {
4292    fn hash<H: Hasher>(&self, state: &mut H) {
4293        self.any_handle.hash(state);
4294    }
4295}
4296
4297#[derive(Debug, Clone, Copy, Eq, PartialEq)]
4298pub struct AnyWeakViewHandle {
4299    window_id: usize,
4300    view_id: usize,
4301    view_type: TypeId,
4302}
4303
4304impl AnyWeakViewHandle {
4305    pub fn id(&self) -> usize {
4306        self.view_id
4307    }
4308
4309    fn is<T: 'static>(&self) -> bool {
4310        TypeId::of::<T>() == self.view_type
4311    }
4312
4313    pub fn upgrade(&self, cx: &impl BorrowAppContext) -> Option<AnyViewHandle> {
4314        cx.read_with(|cx| cx.upgrade_any_view_handle(self))
4315    }
4316
4317    pub fn downcast<T: View>(self) -> Option<WeakViewHandle<T>> {
4318        if self.is::<T>() {
4319            Some(WeakViewHandle {
4320                any_handle: self,
4321                view_type: PhantomData,
4322            })
4323        } else {
4324            None
4325        }
4326    }
4327}
4328
4329impl Hash for AnyWeakViewHandle {
4330    fn hash<H: Hasher>(&self, state: &mut H) {
4331        self.window_id.hash(state);
4332        self.view_id.hash(state);
4333        self.view_type.hash(state);
4334    }
4335}
4336
4337#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
4338pub struct ElementStateId {
4339    view_id: usize,
4340    element_id: usize,
4341    tag: TypeId,
4342}
4343
4344pub struct ElementStateHandle<T> {
4345    value_type: PhantomData<T>,
4346    id: ElementStateId,
4347    ref_counts: Weak<Mutex<RefCounts>>,
4348}
4349
4350impl<T: 'static> ElementStateHandle<T> {
4351    fn new(id: ElementStateId, frame_id: usize, ref_counts: &Arc<Mutex<RefCounts>>) -> Self {
4352        ref_counts.lock().inc_element_state(id, frame_id);
4353        Self {
4354            value_type: PhantomData,
4355            id,
4356            ref_counts: Arc::downgrade(ref_counts),
4357        }
4358    }
4359
4360    pub fn id(&self) -> ElementStateId {
4361        self.id
4362    }
4363
4364    pub fn read<'a>(&self, cx: &'a AppContext) -> &'a T {
4365        cx.element_states
4366            .get(&self.id)
4367            .unwrap()
4368            .downcast_ref()
4369            .unwrap()
4370    }
4371
4372    pub fn update<C, D, R>(&self, cx: &mut C, f: impl FnOnce(&mut T, &mut C) -> R) -> R
4373    where
4374        C: DerefMut<Target = D>,
4375        D: DerefMut<Target = AppContext>,
4376    {
4377        let mut element_state = cx.deref_mut().element_states.remove(&self.id).unwrap();
4378        let result = f(element_state.downcast_mut().unwrap(), cx);
4379        cx.deref_mut().element_states.insert(self.id, element_state);
4380        result
4381    }
4382}
4383
4384impl<T> Drop for ElementStateHandle<T> {
4385    fn drop(&mut self) {
4386        if let Some(ref_counts) = self.ref_counts.upgrade() {
4387            ref_counts.lock().dec_element_state(self.id);
4388        }
4389    }
4390}
4391
4392#[must_use]
4393pub enum Subscription {
4394    Subscription(callback_collection::Subscription<usize, SubscriptionCallback>),
4395    Observation(callback_collection::Subscription<usize, ObservationCallback>),
4396    GlobalSubscription(callback_collection::Subscription<TypeId, GlobalSubscriptionCallback>),
4397    GlobalObservation(callback_collection::Subscription<TypeId, GlobalObservationCallback>),
4398    FocusObservation(callback_collection::Subscription<usize, FocusObservationCallback>),
4399    WindowActivationObservation(callback_collection::Subscription<usize, WindowActivationCallback>),
4400    WindowFullscreenObservation(callback_collection::Subscription<usize, WindowFullscreenCallback>),
4401    WindowBoundsObservation(callback_collection::Subscription<usize, WindowBoundsCallback>),
4402    KeystrokeObservation(callback_collection::Subscription<usize, KeystrokeCallback>),
4403    ReleaseObservation(callback_collection::Subscription<usize, ReleaseObservationCallback>),
4404    ActionObservation(callback_collection::Subscription<(), ActionObservationCallback>),
4405    ActiveLabeledTasksObservation(
4406        callback_collection::Subscription<(), ActiveLabeledTasksCallback>,
4407    ),
4408}
4409
4410impl Subscription {
4411    pub fn id(&self) -> usize {
4412        match self {
4413            Subscription::Subscription(subscription) => subscription.id(),
4414            Subscription::Observation(subscription) => subscription.id(),
4415            Subscription::GlobalSubscription(subscription) => subscription.id(),
4416            Subscription::GlobalObservation(subscription) => subscription.id(),
4417            Subscription::FocusObservation(subscription) => subscription.id(),
4418            Subscription::WindowActivationObservation(subscription) => subscription.id(),
4419            Subscription::WindowFullscreenObservation(subscription) => subscription.id(),
4420            Subscription::WindowBoundsObservation(subscription) => subscription.id(),
4421            Subscription::KeystrokeObservation(subscription) => subscription.id(),
4422            Subscription::ReleaseObservation(subscription) => subscription.id(),
4423            Subscription::ActionObservation(subscription) => subscription.id(),
4424            Subscription::ActiveLabeledTasksObservation(subscription) => subscription.id(),
4425        }
4426    }
4427
4428    pub fn detach(&mut self) {
4429        match self {
4430            Subscription::Subscription(subscription) => subscription.detach(),
4431            Subscription::GlobalSubscription(subscription) => subscription.detach(),
4432            Subscription::Observation(subscription) => subscription.detach(),
4433            Subscription::GlobalObservation(subscription) => subscription.detach(),
4434            Subscription::FocusObservation(subscription) => subscription.detach(),
4435            Subscription::KeystrokeObservation(subscription) => subscription.detach(),
4436            Subscription::WindowActivationObservation(subscription) => subscription.detach(),
4437            Subscription::WindowFullscreenObservation(subscription) => subscription.detach(),
4438            Subscription::WindowBoundsObservation(subscription) => subscription.detach(),
4439            Subscription::ReleaseObservation(subscription) => subscription.detach(),
4440            Subscription::ActionObservation(subscription) => subscription.detach(),
4441            Subscription::ActiveLabeledTasksObservation(subscription) => subscription.detach(),
4442        }
4443    }
4444}
4445
4446#[cfg(test)]
4447mod tests {
4448    use super::*;
4449    use crate::{
4450        actions,
4451        elements::*,
4452        impl_actions,
4453        platform::{MouseButton, MouseButtonEvent},
4454        window::ChildView,
4455    };
4456    use itertools::Itertools;
4457    use postage::{sink::Sink, stream::Stream};
4458    use serde::Deserialize;
4459    use smol::future::poll_once;
4460    use std::{
4461        cell::Cell,
4462        sync::atomic::{AtomicBool, AtomicUsize, Ordering::SeqCst},
4463    };
4464
4465    #[crate::test(self)]
4466    fn test_model_handles(cx: &mut AppContext) {
4467        struct Model {
4468            other: Option<ModelHandle<Model>>,
4469            events: Vec<String>,
4470        }
4471
4472        impl Entity for Model {
4473            type Event = usize;
4474        }
4475
4476        impl Model {
4477            fn new(other: Option<ModelHandle<Self>>, cx: &mut ModelContext<Self>) -> Self {
4478                if let Some(other) = other.as_ref() {
4479                    cx.observe(other, |me, _, _| {
4480                        me.events.push("notified".into());
4481                    })
4482                    .detach();
4483                    cx.subscribe(other, |me, _, event, _| {
4484                        me.events.push(format!("observed event {}", event));
4485                    })
4486                    .detach();
4487                }
4488
4489                Self {
4490                    other,
4491                    events: Vec::new(),
4492                }
4493            }
4494        }
4495
4496        let handle_1 = cx.add_model(|cx| Model::new(None, cx));
4497        let handle_2 = cx.add_model(|cx| Model::new(Some(handle_1.clone()), cx));
4498        assert_eq!(cx.models.len(), 2);
4499
4500        handle_1.update(cx, |model, cx| {
4501            model.events.push("updated".into());
4502            cx.emit(1);
4503            cx.notify();
4504            cx.emit(2);
4505        });
4506        assert_eq!(handle_1.read(cx).events, vec!["updated".to_string()]);
4507        assert_eq!(
4508            handle_2.read(cx).events,
4509            vec![
4510                "observed event 1".to_string(),
4511                "notified".to_string(),
4512                "observed event 2".to_string(),
4513            ]
4514        );
4515
4516        handle_2.update(cx, |model, _| {
4517            drop(handle_1);
4518            model.other.take();
4519        });
4520
4521        assert_eq!(cx.models.len(), 1);
4522        assert!(cx.subscriptions.is_empty());
4523        assert!(cx.observations.is_empty());
4524    }
4525
4526    #[crate::test(self)]
4527    fn test_model_events(cx: &mut AppContext) {
4528        #[derive(Default)]
4529        struct Model {
4530            events: Vec<usize>,
4531        }
4532
4533        impl Entity for Model {
4534            type Event = usize;
4535        }
4536
4537        let handle_1 = cx.add_model(|_| Model::default());
4538        let handle_2 = cx.add_model(|_| Model::default());
4539
4540        handle_1.update(cx, |_, cx| {
4541            cx.subscribe(&handle_2, move |model: &mut Model, emitter, event, cx| {
4542                model.events.push(*event);
4543
4544                cx.subscribe(&emitter, |model, _, event, _| {
4545                    model.events.push(*event * 2);
4546                })
4547                .detach();
4548            })
4549            .detach();
4550        });
4551
4552        handle_2.update(cx, |_, c| c.emit(7));
4553        assert_eq!(handle_1.read(cx).events, vec![7]);
4554
4555        handle_2.update(cx, |_, c| c.emit(5));
4556        assert_eq!(handle_1.read(cx).events, vec![7, 5, 10]);
4557    }
4558
4559    #[crate::test(self)]
4560    fn test_model_emit_before_subscribe_in_same_update_cycle(cx: &mut AppContext) {
4561        #[derive(Default)]
4562        struct Model;
4563
4564        impl Entity for Model {
4565            type Event = ();
4566        }
4567
4568        let events = Rc::new(RefCell::new(Vec::new()));
4569        cx.add_model(|cx| {
4570            drop(cx.subscribe(&cx.handle(), {
4571                let events = events.clone();
4572                move |_, _, _, _| events.borrow_mut().push("dropped before flush")
4573            }));
4574            cx.subscribe(&cx.handle(), {
4575                let events = events.clone();
4576                move |_, _, _, _| events.borrow_mut().push("before emit")
4577            })
4578            .detach();
4579            cx.emit(());
4580            cx.subscribe(&cx.handle(), {
4581                let events = events.clone();
4582                move |_, _, _, _| events.borrow_mut().push("after emit")
4583            })
4584            .detach();
4585            Model
4586        });
4587        assert_eq!(*events.borrow(), ["before emit"]);
4588    }
4589
4590    #[crate::test(self)]
4591    fn test_observe_and_notify_from_model(cx: &mut AppContext) {
4592        #[derive(Default)]
4593        struct Model {
4594            count: usize,
4595            events: Vec<usize>,
4596        }
4597
4598        impl Entity for Model {
4599            type Event = ();
4600        }
4601
4602        let handle_1 = cx.add_model(|_| Model::default());
4603        let handle_2 = cx.add_model(|_| Model::default());
4604
4605        handle_1.update(cx, |_, c| {
4606            c.observe(&handle_2, move |model, observed, c| {
4607                model.events.push(observed.read(c).count);
4608                c.observe(&observed, |model, observed, c| {
4609                    model.events.push(observed.read(c).count * 2);
4610                })
4611                .detach();
4612            })
4613            .detach();
4614        });
4615
4616        handle_2.update(cx, |model, c| {
4617            model.count = 7;
4618            c.notify()
4619        });
4620        assert_eq!(handle_1.read(cx).events, vec![7]);
4621
4622        handle_2.update(cx, |model, c| {
4623            model.count = 5;
4624            c.notify()
4625        });
4626        assert_eq!(handle_1.read(cx).events, vec![7, 5, 10])
4627    }
4628
4629    #[crate::test(self)]
4630    fn test_model_notify_before_observe_in_same_update_cycle(cx: &mut AppContext) {
4631        #[derive(Default)]
4632        struct Model;
4633
4634        impl Entity for Model {
4635            type Event = ();
4636        }
4637
4638        let events = Rc::new(RefCell::new(Vec::new()));
4639        cx.add_model(|cx| {
4640            drop(cx.observe(&cx.handle(), {
4641                let events = events.clone();
4642                move |_, _, _| events.borrow_mut().push("dropped before flush")
4643            }));
4644            cx.observe(&cx.handle(), {
4645                let events = events.clone();
4646                move |_, _, _| events.borrow_mut().push("before notify")
4647            })
4648            .detach();
4649            cx.notify();
4650            cx.observe(&cx.handle(), {
4651                let events = events.clone();
4652                move |_, _, _| events.borrow_mut().push("after notify")
4653            })
4654            .detach();
4655            Model
4656        });
4657        assert_eq!(*events.borrow(), ["before notify"]);
4658    }
4659
4660    #[crate::test(self)]
4661    fn test_defer_and_after_window_update(cx: &mut TestAppContext) {
4662        struct View {
4663            render_count: usize,
4664        }
4665
4666        impl Entity for View {
4667            type Event = usize;
4668        }
4669
4670        impl super::View for View {
4671            fn render(&mut self, _: &mut ViewContext<Self>) -> AnyElement<Self> {
4672                post_inc(&mut self.render_count);
4673                Empty::new().into_any()
4674            }
4675
4676            fn ui_name() -> &'static str {
4677                "View"
4678            }
4679        }
4680
4681        let (_, view) = cx.add_window(|_| View { render_count: 0 });
4682        let called_defer = Rc::new(AtomicBool::new(false));
4683        let called_after_window_update = Rc::new(AtomicBool::new(false));
4684
4685        view.update(cx, |this, cx| {
4686            assert_eq!(this.render_count, 1);
4687            cx.defer({
4688                let called_defer = called_defer.clone();
4689                move |this, _| {
4690                    assert_eq!(this.render_count, 1);
4691                    called_defer.store(true, SeqCst);
4692                }
4693            });
4694            cx.after_window_update({
4695                let called_after_window_update = called_after_window_update.clone();
4696                move |this, cx| {
4697                    assert_eq!(this.render_count, 2);
4698                    called_after_window_update.store(true, SeqCst);
4699                    cx.notify();
4700                }
4701            });
4702            assert!(!called_defer.load(SeqCst));
4703            assert!(!called_after_window_update.load(SeqCst));
4704            cx.notify();
4705        });
4706
4707        assert!(called_defer.load(SeqCst));
4708        assert!(called_after_window_update.load(SeqCst));
4709        assert_eq!(view.read_with(cx, |view, _| view.render_count), 3);
4710    }
4711
4712    #[crate::test(self)]
4713    fn test_view_handles(cx: &mut TestAppContext) {
4714        struct View {
4715            other: Option<ViewHandle<View>>,
4716            events: Vec<String>,
4717        }
4718
4719        impl Entity for View {
4720            type Event = usize;
4721        }
4722
4723        impl super::View for View {
4724            fn render(&mut self, _: &mut ViewContext<Self>) -> AnyElement<Self> {
4725                Empty::new().into_any()
4726            }
4727
4728            fn ui_name() -> &'static str {
4729                "View"
4730            }
4731        }
4732
4733        impl View {
4734            fn new(other: Option<ViewHandle<View>>, cx: &mut ViewContext<Self>) -> Self {
4735                if let Some(other) = other.as_ref() {
4736                    cx.subscribe(other, |me, _, event, _| {
4737                        me.events.push(format!("observed event {}", event));
4738                    })
4739                    .detach();
4740                }
4741                Self {
4742                    other,
4743                    events: Vec::new(),
4744                }
4745            }
4746        }
4747
4748        let (window_id, _root_view) = cx.add_window(|cx| View::new(None, cx));
4749        let handle_1 = cx.add_view(window_id, |cx| View::new(None, cx));
4750        let handle_2 = cx.add_view(window_id, |cx| View::new(Some(handle_1.clone()), cx));
4751        assert_eq!(cx.read(|cx| cx.views.len()), 3);
4752
4753        handle_1.update(cx, |view, cx| {
4754            view.events.push("updated".into());
4755            cx.emit(1);
4756            cx.emit(2);
4757        });
4758        handle_1.read_with(cx, |view, _| {
4759            assert_eq!(view.events, vec!["updated".to_string()]);
4760        });
4761        handle_2.read_with(cx, |view, _| {
4762            assert_eq!(
4763                view.events,
4764                vec![
4765                    "observed event 1".to_string(),
4766                    "observed event 2".to_string(),
4767                ]
4768            );
4769        });
4770
4771        handle_2.update(cx, |view, _| {
4772            drop(handle_1);
4773            view.other.take();
4774        });
4775
4776        cx.read(|cx| {
4777            assert_eq!(cx.views.len(), 2);
4778            assert!(cx.subscriptions.is_empty());
4779            assert!(cx.observations.is_empty());
4780        });
4781    }
4782
4783    #[crate::test(self)]
4784    fn test_add_window(cx: &mut AppContext) {
4785        struct View {
4786            mouse_down_count: Arc<AtomicUsize>,
4787        }
4788
4789        impl Entity for View {
4790            type Event = ();
4791        }
4792
4793        impl super::View for View {
4794            fn render(&mut self, cx: &mut ViewContext<Self>) -> AnyElement<Self> {
4795                enum Handler {}
4796                let mouse_down_count = self.mouse_down_count.clone();
4797                MouseEventHandler::<Handler, _>::new(0, cx, |_, _| Empty::new())
4798                    .on_down(MouseButton::Left, move |_, _, _| {
4799                        mouse_down_count.fetch_add(1, SeqCst);
4800                    })
4801                    .into_any()
4802            }
4803
4804            fn ui_name() -> &'static str {
4805                "View"
4806            }
4807        }
4808
4809        let mouse_down_count = Arc::new(AtomicUsize::new(0));
4810        let (window_id, _) = cx.add_window(Default::default(), |_| View {
4811            mouse_down_count: mouse_down_count.clone(),
4812        });
4813
4814        cx.update_window(window_id, |cx| {
4815            // Ensure window's root element is in a valid lifecycle state.
4816            cx.dispatch_event(
4817                Event::MouseDown(MouseButtonEvent {
4818                    position: Default::default(),
4819                    button: MouseButton::Left,
4820                    modifiers: Default::default(),
4821                    click_count: 1,
4822                }),
4823                false,
4824            );
4825            assert_eq!(mouse_down_count.load(SeqCst), 1);
4826        });
4827    }
4828
4829    #[crate::test(self)]
4830    fn test_entity_release_hooks(cx: &mut AppContext) {
4831        struct Model {
4832            released: Rc<Cell<bool>>,
4833        }
4834
4835        struct View {
4836            released: Rc<Cell<bool>>,
4837        }
4838
4839        impl Entity for Model {
4840            type Event = ();
4841
4842            fn release(&mut self, _: &mut AppContext) {
4843                self.released.set(true);
4844            }
4845        }
4846
4847        impl Entity for View {
4848            type Event = ();
4849
4850            fn release(&mut self, _: &mut AppContext) {
4851                self.released.set(true);
4852            }
4853        }
4854
4855        impl super::View for View {
4856            fn ui_name() -> &'static str {
4857                "View"
4858            }
4859
4860            fn render(&mut self, _: &mut ViewContext<Self>) -> AnyElement<Self> {
4861                Empty::new().into_any()
4862            }
4863        }
4864
4865        let model_released = Rc::new(Cell::new(false));
4866        let model_release_observed = Rc::new(Cell::new(false));
4867        let view_released = Rc::new(Cell::new(false));
4868        let view_release_observed = Rc::new(Cell::new(false));
4869
4870        let model = cx.add_model(|_| Model {
4871            released: model_released.clone(),
4872        });
4873        let (window_id, view) = cx.add_window(Default::default(), |_| View {
4874            released: view_released.clone(),
4875        });
4876        assert!(!model_released.get());
4877        assert!(!view_released.get());
4878
4879        cx.observe_release(&model, {
4880            let model_release_observed = model_release_observed.clone();
4881            move |_, _| model_release_observed.set(true)
4882        })
4883        .detach();
4884        cx.observe_release(&view, {
4885            let view_release_observed = view_release_observed.clone();
4886            move |_, _| view_release_observed.set(true)
4887        })
4888        .detach();
4889
4890        cx.update(move |_| {
4891            drop(model);
4892        });
4893        assert!(model_released.get());
4894        assert!(model_release_observed.get());
4895
4896        drop(view);
4897        cx.update_window(window_id, |cx| cx.remove_window());
4898        assert!(view_released.get());
4899        assert!(view_release_observed.get());
4900    }
4901
4902    #[crate::test(self)]
4903    fn test_view_events(cx: &mut TestAppContext) {
4904        struct Model;
4905
4906        impl Entity for Model {
4907            type Event = String;
4908        }
4909
4910        let (window_id, handle_1) = cx.add_window(|_| TestView::default());
4911        let handle_2 = cx.add_view(window_id, |_| TestView::default());
4912        let handle_3 = cx.add_model(|_| Model);
4913
4914        handle_1.update(cx, |_, cx| {
4915            cx.subscribe(&handle_2, move |me, emitter, event, cx| {
4916                me.events.push(event.clone());
4917
4918                cx.subscribe(&emitter, |me, _, event, _| {
4919                    me.events.push(format!("{event} from inner"));
4920                })
4921                .detach();
4922            })
4923            .detach();
4924
4925            cx.subscribe(&handle_3, |me, _, event, _| {
4926                me.events.push(event.clone());
4927            })
4928            .detach();
4929        });
4930
4931        handle_2.update(cx, |_, c| c.emit("7".into()));
4932        handle_1.read_with(cx, |view, _| assert_eq!(view.events, ["7"]));
4933
4934        handle_2.update(cx, |_, c| c.emit("5".into()));
4935        handle_1.read_with(cx, |view, _| {
4936            assert_eq!(view.events, ["7", "5", "5 from inner"])
4937        });
4938
4939        handle_3.update(cx, |_, c| c.emit("9".into()));
4940        handle_1.read_with(cx, |view, _| {
4941            assert_eq!(view.events, ["7", "5", "5 from inner", "9"])
4942        });
4943    }
4944
4945    #[crate::test(self)]
4946    fn test_global_events(cx: &mut AppContext) {
4947        #[derive(Clone, Debug, Eq, PartialEq)]
4948        struct GlobalEvent(u64);
4949
4950        let events = Rc::new(RefCell::new(Vec::new()));
4951        let first_subscription;
4952        let second_subscription;
4953
4954        {
4955            let events = events.clone();
4956            first_subscription = cx.subscribe_global(move |e: &GlobalEvent, _| {
4957                events.borrow_mut().push(("First", e.clone()));
4958            });
4959        }
4960
4961        {
4962            let events = events.clone();
4963            second_subscription = cx.subscribe_global(move |e: &GlobalEvent, _| {
4964                events.borrow_mut().push(("Second", e.clone()));
4965            });
4966        }
4967
4968        cx.update(|cx| {
4969            cx.emit_global(GlobalEvent(1));
4970            cx.emit_global(GlobalEvent(2));
4971        });
4972
4973        drop(first_subscription);
4974
4975        cx.update(|cx| {
4976            cx.emit_global(GlobalEvent(3));
4977        });
4978
4979        drop(second_subscription);
4980
4981        cx.update(|cx| {
4982            cx.emit_global(GlobalEvent(4));
4983        });
4984
4985        assert_eq!(
4986            &*events.borrow(),
4987            &[
4988                ("First", GlobalEvent(1)),
4989                ("Second", GlobalEvent(1)),
4990                ("First", GlobalEvent(2)),
4991                ("Second", GlobalEvent(2)),
4992                ("Second", GlobalEvent(3)),
4993            ]
4994        );
4995    }
4996
4997    #[crate::test(self)]
4998    fn test_global_events_emitted_before_subscription_in_same_update_cycle(cx: &mut AppContext) {
4999        let events = Rc::new(RefCell::new(Vec::new()));
5000        cx.update(|cx| {
5001            {
5002                let events = events.clone();
5003                drop(cx.subscribe_global(move |_: &(), _| {
5004                    events.borrow_mut().push("dropped before emit");
5005                }));
5006            }
5007
5008            {
5009                let events = events.clone();
5010                cx.subscribe_global(move |_: &(), _| {
5011                    events.borrow_mut().push("before emit");
5012                })
5013                .detach();
5014            }
5015
5016            cx.emit_global(());
5017
5018            {
5019                let events = events.clone();
5020                cx.subscribe_global(move |_: &(), _| {
5021                    events.borrow_mut().push("after emit");
5022                })
5023                .detach();
5024            }
5025        });
5026
5027        assert_eq!(*events.borrow(), ["before emit"]);
5028    }
5029
5030    #[crate::test(self)]
5031    fn test_global_nested_events(cx: &mut AppContext) {
5032        #[derive(Clone, Debug, Eq, PartialEq)]
5033        struct GlobalEvent(u64);
5034
5035        let events = Rc::new(RefCell::new(Vec::new()));
5036
5037        {
5038            let events = events.clone();
5039            cx.subscribe_global(move |e: &GlobalEvent, cx| {
5040                events.borrow_mut().push(("Outer", e.clone()));
5041
5042                if e.0 == 1 {
5043                    let events = events.clone();
5044                    cx.subscribe_global(move |e: &GlobalEvent, _| {
5045                        events.borrow_mut().push(("Inner", e.clone()));
5046                    })
5047                    .detach();
5048                }
5049            })
5050            .detach();
5051        }
5052
5053        cx.update(|cx| {
5054            cx.emit_global(GlobalEvent(1));
5055            cx.emit_global(GlobalEvent(2));
5056            cx.emit_global(GlobalEvent(3));
5057        });
5058        cx.update(|cx| {
5059            cx.emit_global(GlobalEvent(4));
5060        });
5061
5062        assert_eq!(
5063            &*events.borrow(),
5064            &[
5065                ("Outer", GlobalEvent(1)),
5066                ("Outer", GlobalEvent(2)),
5067                ("Outer", GlobalEvent(3)),
5068                ("Outer", GlobalEvent(4)),
5069                ("Inner", GlobalEvent(4)),
5070            ]
5071        );
5072    }
5073
5074    #[crate::test(self)]
5075    fn test_global(cx: &mut AppContext) {
5076        type Global = usize;
5077
5078        let observation_count = Rc::new(RefCell::new(0));
5079        let subscription = cx.observe_global::<Global, _>({
5080            let observation_count = observation_count.clone();
5081            move |_| {
5082                *observation_count.borrow_mut() += 1;
5083            }
5084        });
5085
5086        assert!(!cx.has_global::<Global>());
5087        assert_eq!(cx.default_global::<Global>(), &0);
5088        assert_eq!(*observation_count.borrow(), 1);
5089        assert!(cx.has_global::<Global>());
5090        assert_eq!(
5091            cx.update_global::<Global, _, _>(|global, _| {
5092                *global = 1;
5093                "Update Result"
5094            }),
5095            "Update Result"
5096        );
5097        assert_eq!(*observation_count.borrow(), 2);
5098        assert_eq!(cx.global::<Global>(), &1);
5099
5100        drop(subscription);
5101        cx.update_global::<Global, _, _>(|global, _| {
5102            *global = 2;
5103        });
5104        assert_eq!(*observation_count.borrow(), 2);
5105
5106        type OtherGlobal = f32;
5107
5108        let observation_count = Rc::new(RefCell::new(0));
5109        cx.observe_global::<OtherGlobal, _>({
5110            let observation_count = observation_count.clone();
5111            move |_| {
5112                *observation_count.borrow_mut() += 1;
5113            }
5114        })
5115        .detach();
5116
5117        assert_eq!(
5118            cx.update_default_global::<OtherGlobal, _, _>(|global, _| {
5119                assert_eq!(global, &0.0);
5120                *global = 2.0;
5121                "Default update result"
5122            }),
5123            "Default update result"
5124        );
5125        assert_eq!(cx.global::<OtherGlobal>(), &2.0);
5126        assert_eq!(*observation_count.borrow(), 1);
5127    }
5128
5129    #[crate::test(self)]
5130    fn test_dropping_subscribers(cx: &mut TestAppContext) {
5131        struct Model;
5132
5133        impl Entity for Model {
5134            type Event = ();
5135        }
5136
5137        let (window_id, _root_view) = cx.add_window(|_| TestView::default());
5138        let observing_view = cx.add_view(window_id, |_| TestView::default());
5139        let emitting_view = cx.add_view(window_id, |_| TestView::default());
5140        let observing_model = cx.add_model(|_| Model);
5141        let observed_model = cx.add_model(|_| Model);
5142
5143        observing_view.update(cx, |_, cx| {
5144            cx.subscribe(&emitting_view, |_, _, _, _| {}).detach();
5145            cx.subscribe(&observed_model, |_, _, _, _| {}).detach();
5146        });
5147        observing_model.update(cx, |_, cx| {
5148            cx.subscribe(&observed_model, |_, _, _, _| {}).detach();
5149        });
5150
5151        cx.update(|_| {
5152            drop(observing_view);
5153            drop(observing_model);
5154        });
5155
5156        emitting_view.update(cx, |_, cx| cx.emit(Default::default()));
5157        observed_model.update(cx, |_, cx| cx.emit(()));
5158    }
5159
5160    #[crate::test(self)]
5161    fn test_view_emit_before_subscribe_in_same_update_cycle(cx: &mut AppContext) {
5162        let (_, view) = cx.add_window::<TestView, _>(Default::default(), |cx| {
5163            drop(cx.subscribe(&cx.handle(), {
5164                move |this, _, _, _| this.events.push("dropped before flush".into())
5165            }));
5166            cx.subscribe(&cx.handle(), {
5167                move |this, _, _, _| this.events.push("before emit".into())
5168            })
5169            .detach();
5170            cx.emit("the event".into());
5171            cx.subscribe(&cx.handle(), {
5172                move |this, _, _, _| this.events.push("after emit".into())
5173            })
5174            .detach();
5175            TestView { events: Vec::new() }
5176        });
5177
5178        assert_eq!(view.read(cx).events, ["before emit"]);
5179    }
5180
5181    #[crate::test(self)]
5182    fn test_observe_and_notify_from_view(cx: &mut TestAppContext) {
5183        #[derive(Default)]
5184        struct Model {
5185            state: String,
5186        }
5187
5188        impl Entity for Model {
5189            type Event = ();
5190        }
5191
5192        let (_, view) = cx.add_window(|_| TestView::default());
5193        let model = cx.add_model(|_| Model {
5194            state: "old-state".into(),
5195        });
5196
5197        view.update(cx, |_, c| {
5198            c.observe(&model, |me, observed, cx| {
5199                me.events.push(observed.read(cx).state.clone())
5200            })
5201            .detach();
5202        });
5203
5204        model.update(cx, |model, cx| {
5205            model.state = "new-state".into();
5206            cx.notify();
5207        });
5208        view.read_with(cx, |view, _| assert_eq!(view.events, ["new-state"]));
5209    }
5210
5211    #[crate::test(self)]
5212    fn test_view_notify_before_observe_in_same_update_cycle(cx: &mut AppContext) {
5213        let (_, view) = cx.add_window::<TestView, _>(Default::default(), |cx| {
5214            drop(cx.observe(&cx.handle(), {
5215                move |this, _, _| this.events.push("dropped before flush".into())
5216            }));
5217            cx.observe(&cx.handle(), {
5218                move |this, _, _| this.events.push("before notify".into())
5219            })
5220            .detach();
5221            cx.notify();
5222            cx.observe(&cx.handle(), {
5223                move |this, _, _| this.events.push("after notify".into())
5224            })
5225            .detach();
5226            TestView { events: Vec::new() }
5227        });
5228
5229        assert_eq!(view.read(cx).events, ["before notify"]);
5230    }
5231
5232    #[crate::test(self)]
5233    fn test_notify_and_drop_observe_subscription_in_same_update_cycle(cx: &mut TestAppContext) {
5234        struct Model;
5235        impl Entity for Model {
5236            type Event = ();
5237        }
5238
5239        let model = cx.add_model(|_| Model);
5240        let (_, view) = cx.add_window(|_| TestView::default());
5241
5242        view.update(cx, |_, cx| {
5243            model.update(cx, |_, cx| cx.notify());
5244            drop(cx.observe(&model, move |this, _, _| {
5245                this.events.push("model notified".into());
5246            }));
5247            model.update(cx, |_, cx| cx.notify());
5248        });
5249
5250        for _ in 0..3 {
5251            model.update(cx, |_, cx| cx.notify());
5252        }
5253        view.read_with(cx, |view, _| assert_eq!(view.events, Vec::<&str>::new()));
5254    }
5255
5256    #[crate::test(self)]
5257    fn test_dropping_observers(cx: &mut TestAppContext) {
5258        struct Model;
5259
5260        impl Entity for Model {
5261            type Event = ();
5262        }
5263
5264        let (window_id, _root_view) = cx.add_window(|_| TestView::default());
5265        let observing_view = cx.add_view(window_id, |_| TestView::default());
5266        let observing_model = cx.add_model(|_| Model);
5267        let observed_model = cx.add_model(|_| Model);
5268
5269        observing_view.update(cx, |_, cx| {
5270            cx.observe(&observed_model, |_, _, _| {}).detach();
5271        });
5272        observing_model.update(cx, |_, cx| {
5273            cx.observe(&observed_model, |_, _, _| {}).detach();
5274        });
5275
5276        cx.update(|_| {
5277            drop(observing_view);
5278            drop(observing_model);
5279        });
5280
5281        observed_model.update(cx, |_, cx| cx.notify());
5282    }
5283
5284    #[crate::test(self)]
5285    fn test_dropping_subscriptions_during_callback(cx: &mut TestAppContext) {
5286        struct Model;
5287
5288        impl Entity for Model {
5289            type Event = u64;
5290        }
5291
5292        // Events
5293        let observing_model = cx.add_model(|_| Model);
5294        let observed_model = cx.add_model(|_| Model);
5295
5296        let events = Rc::new(RefCell::new(Vec::new()));
5297
5298        observing_model.update(cx, |_, cx| {
5299            let events = events.clone();
5300            let subscription = Rc::new(RefCell::new(None));
5301            *subscription.borrow_mut() = Some(cx.subscribe(&observed_model, {
5302                let subscription = subscription.clone();
5303                move |_, _, e, _| {
5304                    subscription.borrow_mut().take();
5305                    events.borrow_mut().push(*e);
5306                }
5307            }));
5308        });
5309
5310        observed_model.update(cx, |_, cx| {
5311            cx.emit(1);
5312            cx.emit(2);
5313        });
5314
5315        assert_eq!(*events.borrow(), [1]);
5316
5317        // Global Events
5318        #[derive(Clone, Debug, Eq, PartialEq)]
5319        struct GlobalEvent(u64);
5320
5321        let events = Rc::new(RefCell::new(Vec::new()));
5322
5323        {
5324            let events = events.clone();
5325            let subscription = Rc::new(RefCell::new(None));
5326            *subscription.borrow_mut() = Some(cx.subscribe_global({
5327                let subscription = subscription.clone();
5328                move |e: &GlobalEvent, _| {
5329                    subscription.borrow_mut().take();
5330                    events.borrow_mut().push(e.clone());
5331                }
5332            }));
5333        }
5334
5335        cx.update(|cx| {
5336            cx.emit_global(GlobalEvent(1));
5337            cx.emit_global(GlobalEvent(2));
5338        });
5339
5340        assert_eq!(*events.borrow(), [GlobalEvent(1)]);
5341
5342        // Model Observation
5343        let observing_model = cx.add_model(|_| Model);
5344        let observed_model = cx.add_model(|_| Model);
5345
5346        let observation_count = Rc::new(RefCell::new(0));
5347
5348        observing_model.update(cx, |_, cx| {
5349            let observation_count = observation_count.clone();
5350            let subscription = Rc::new(RefCell::new(None));
5351            *subscription.borrow_mut() = Some(cx.observe(&observed_model, {
5352                let subscription = subscription.clone();
5353                move |_, _, _| {
5354                    subscription.borrow_mut().take();
5355                    *observation_count.borrow_mut() += 1;
5356                }
5357            }));
5358        });
5359
5360        observed_model.update(cx, |_, cx| {
5361            cx.notify();
5362        });
5363
5364        observed_model.update(cx, |_, cx| {
5365            cx.notify();
5366        });
5367
5368        assert_eq!(*observation_count.borrow(), 1);
5369
5370        // View Observation
5371        struct View;
5372
5373        impl Entity for View {
5374            type Event = ();
5375        }
5376
5377        impl super::View for View {
5378            fn render(&mut self, _: &mut ViewContext<Self>) -> AnyElement<Self> {
5379                Empty::new().into_any()
5380            }
5381
5382            fn ui_name() -> &'static str {
5383                "View"
5384            }
5385        }
5386
5387        let (window_id, _root_view) = cx.add_window(|_| View);
5388        let observing_view = cx.add_view(window_id, |_| View);
5389        let observed_view = cx.add_view(window_id, |_| View);
5390
5391        let observation_count = Rc::new(RefCell::new(0));
5392        observing_view.update(cx, |_, cx| {
5393            let observation_count = observation_count.clone();
5394            let subscription = Rc::new(RefCell::new(None));
5395            *subscription.borrow_mut() = Some(cx.observe(&observed_view, {
5396                let subscription = subscription.clone();
5397                move |_, _, _| {
5398                    subscription.borrow_mut().take();
5399                    *observation_count.borrow_mut() += 1;
5400                }
5401            }));
5402        });
5403
5404        observed_view.update(cx, |_, cx| {
5405            cx.notify();
5406        });
5407
5408        observed_view.update(cx, |_, cx| {
5409            cx.notify();
5410        });
5411
5412        assert_eq!(*observation_count.borrow(), 1);
5413
5414        // Global Observation
5415        let observation_count = Rc::new(RefCell::new(0));
5416        let subscription = Rc::new(RefCell::new(None));
5417        *subscription.borrow_mut() = Some(cx.observe_global::<(), _>({
5418            let observation_count = observation_count.clone();
5419            let subscription = subscription.clone();
5420            move |_| {
5421                subscription.borrow_mut().take();
5422                *observation_count.borrow_mut() += 1;
5423            }
5424        }));
5425
5426        cx.update(|cx| {
5427            cx.default_global::<()>();
5428            cx.set_global(());
5429        });
5430        assert_eq!(*observation_count.borrow(), 1);
5431    }
5432
5433    #[crate::test(self)]
5434    fn test_focus(cx: &mut TestAppContext) {
5435        struct View {
5436            name: String,
5437            events: Arc<Mutex<Vec<String>>>,
5438            child: Option<AnyViewHandle>,
5439        }
5440
5441        impl Entity for View {
5442            type Event = ();
5443        }
5444
5445        impl super::View for View {
5446            fn render(&mut self, cx: &mut ViewContext<Self>) -> AnyElement<Self> {
5447                self.child
5448                    .as_ref()
5449                    .map(|child| ChildView::new(child, cx).into_any())
5450                    .unwrap_or(Empty::new().into_any())
5451            }
5452
5453            fn ui_name() -> &'static str {
5454                "View"
5455            }
5456
5457            fn focus_in(&mut self, focused: AnyViewHandle, cx: &mut ViewContext<Self>) {
5458                if cx.handle().id() == focused.id() {
5459                    self.events.lock().push(format!("{} focused", &self.name));
5460                }
5461            }
5462
5463            fn focus_out(&mut self, blurred: AnyViewHandle, cx: &mut ViewContext<Self>) {
5464                if cx.handle().id() == blurred.id() {
5465                    self.events.lock().push(format!("{} blurred", &self.name));
5466                }
5467            }
5468        }
5469
5470        let view_events: Arc<Mutex<Vec<String>>> = Default::default();
5471        let (window_id, view_1) = cx.add_window(|_| View {
5472            events: view_events.clone(),
5473            name: "view 1".to_string(),
5474            child: None,
5475        });
5476        let view_2 = cx
5477            .update_window(window_id, |cx| {
5478                let view_2 = cx.add_view(|_| View {
5479                    events: view_events.clone(),
5480                    name: "view 2".to_string(),
5481                    child: None,
5482                });
5483                view_1.update(cx, |view_1, cx| {
5484                    view_1.child = Some(view_2.clone().into_any());
5485                    cx.notify();
5486                });
5487                view_2
5488            })
5489            .unwrap();
5490
5491        let observed_events: Arc<Mutex<Vec<String>>> = Default::default();
5492        view_1.update(cx, |_, cx| {
5493            cx.observe_focus(&view_2, {
5494                let observed_events = observed_events.clone();
5495                move |this, view, focused, cx| {
5496                    let label = if focused { "focus" } else { "blur" };
5497                    observed_events.lock().push(format!(
5498                        "{} observed {}'s {}",
5499                        this.name,
5500                        view.read(cx).name,
5501                        label
5502                    ))
5503                }
5504            })
5505            .detach();
5506        });
5507        view_2.update(cx, |_, cx| {
5508            cx.observe_focus(&view_1, {
5509                let observed_events = observed_events.clone();
5510                move |this, view, focused, cx| {
5511                    let label = if focused { "focus" } else { "blur" };
5512                    observed_events.lock().push(format!(
5513                        "{} observed {}'s {}",
5514                        this.name,
5515                        view.read(cx).name,
5516                        label
5517                    ))
5518                }
5519            })
5520            .detach();
5521        });
5522        assert_eq!(mem::take(&mut *view_events.lock()), ["view 1 focused"]);
5523        assert_eq!(mem::take(&mut *observed_events.lock()), Vec::<&str>::new());
5524
5525        view_1.update(cx, |_, cx| {
5526            // Ensure only the last focus event is honored.
5527            cx.focus(&view_2);
5528            cx.focus(&view_1);
5529            cx.focus(&view_2);
5530        });
5531
5532        assert_eq!(
5533            mem::take(&mut *view_events.lock()),
5534            ["view 1 blurred", "view 2 focused"],
5535        );
5536        assert_eq!(
5537            mem::take(&mut *observed_events.lock()),
5538            [
5539                "view 2 observed view 1's blur",
5540                "view 1 observed view 2's focus"
5541            ]
5542        );
5543
5544        view_1.update(cx, |_, cx| cx.focus(&view_1));
5545        assert_eq!(
5546            mem::take(&mut *view_events.lock()),
5547            ["view 2 blurred", "view 1 focused"],
5548        );
5549        assert_eq!(
5550            mem::take(&mut *observed_events.lock()),
5551            [
5552                "view 1 observed view 2's blur",
5553                "view 2 observed view 1's focus"
5554            ]
5555        );
5556
5557        view_1.update(cx, |_, cx| cx.focus(&view_2));
5558        assert_eq!(
5559            mem::take(&mut *view_events.lock()),
5560            ["view 1 blurred", "view 2 focused"],
5561        );
5562        assert_eq!(
5563            mem::take(&mut *observed_events.lock()),
5564            [
5565                "view 2 observed view 1's blur",
5566                "view 1 observed view 2's focus"
5567            ]
5568        );
5569
5570        println!("=====================");
5571        view_1.update(cx, |view, _| {
5572            drop(view_2);
5573            view.child = None;
5574        });
5575        assert_eq!(mem::take(&mut *view_events.lock()), ["view 1 focused"]);
5576        assert_eq!(mem::take(&mut *observed_events.lock()), Vec::<&str>::new());
5577    }
5578
5579    #[crate::test(self)]
5580    fn test_deserialize_actions(cx: &mut AppContext) {
5581        #[derive(Clone, Debug, Deserialize, PartialEq, Eq)]
5582        pub struct ComplexAction {
5583            arg: String,
5584            count: usize,
5585        }
5586
5587        actions!(test::something, [SimpleAction]);
5588        impl_actions!(test::something, [ComplexAction]);
5589
5590        cx.add_global_action(move |_: &SimpleAction, _: &mut AppContext| {});
5591        cx.add_global_action(move |_: &ComplexAction, _: &mut AppContext| {});
5592
5593        let action1 = cx
5594            .deserialize_action(
5595                "test::something::ComplexAction",
5596                Some(serde_json::from_str(r#"{"arg": "a", "count": 5}"#).unwrap()),
5597            )
5598            .unwrap();
5599        let action2 = cx
5600            .deserialize_action("test::something::SimpleAction", None)
5601            .unwrap();
5602        assert_eq!(
5603            action1.as_any().downcast_ref::<ComplexAction>().unwrap(),
5604            &ComplexAction {
5605                arg: "a".to_string(),
5606                count: 5,
5607            }
5608        );
5609        assert_eq!(
5610            action2.as_any().downcast_ref::<SimpleAction>().unwrap(),
5611            &SimpleAction
5612        );
5613    }
5614
5615    #[crate::test(self)]
5616    fn test_dispatch_action(cx: &mut AppContext) {
5617        struct ViewA {
5618            id: usize,
5619            child: Option<AnyViewHandle>,
5620        }
5621
5622        impl Entity for ViewA {
5623            type Event = ();
5624        }
5625
5626        impl View for ViewA {
5627            fn render(&mut self, cx: &mut ViewContext<Self>) -> AnyElement<Self> {
5628                self.child
5629                    .as_ref()
5630                    .map(|child| ChildView::new(child, cx).into_any())
5631                    .unwrap_or(Empty::new().into_any())
5632            }
5633
5634            fn ui_name() -> &'static str {
5635                "View"
5636            }
5637        }
5638
5639        struct ViewB {
5640            id: usize,
5641            child: Option<AnyViewHandle>,
5642        }
5643
5644        impl Entity for ViewB {
5645            type Event = ();
5646        }
5647
5648        impl View for ViewB {
5649            fn render(&mut self, cx: &mut ViewContext<Self>) -> AnyElement<Self> {
5650                self.child
5651                    .as_ref()
5652                    .map(|child| ChildView::new(child, cx).into_any())
5653                    .unwrap_or(Empty::new().into_any())
5654            }
5655
5656            fn ui_name() -> &'static str {
5657                "View"
5658            }
5659        }
5660
5661        #[derive(Clone, Default, Deserialize, PartialEq)]
5662        pub struct Action(pub String);
5663
5664        impl_actions!(test, [Action]);
5665
5666        let actions = Rc::new(RefCell::new(Vec::new()));
5667
5668        cx.add_global_action({
5669            let actions = actions.clone();
5670            move |_: &Action, _: &mut AppContext| {
5671                actions.borrow_mut().push("global".to_string());
5672            }
5673        });
5674
5675        cx.add_action({
5676            let actions = actions.clone();
5677            move |view: &mut ViewA, action: &Action, cx| {
5678                assert_eq!(action.0, "bar");
5679                cx.propagate_action();
5680                actions.borrow_mut().push(format!("{} a", view.id));
5681            }
5682        });
5683
5684        cx.add_action({
5685            let actions = actions.clone();
5686            move |view: &mut ViewA, _: &Action, cx| {
5687                if view.id != 1 {
5688                    cx.add_view(|cx| {
5689                        cx.propagate_action(); // Still works on a nested ViewContext
5690                        ViewB { id: 5, child: None }
5691                    });
5692                }
5693                actions.borrow_mut().push(format!("{} b", view.id));
5694            }
5695        });
5696
5697        cx.add_action({
5698            let actions = actions.clone();
5699            move |view: &mut ViewB, _: &Action, cx| {
5700                cx.propagate_action();
5701                actions.borrow_mut().push(format!("{} c", view.id));
5702            }
5703        });
5704
5705        cx.add_action({
5706            let actions = actions.clone();
5707            move |view: &mut ViewB, _: &Action, cx| {
5708                cx.propagate_action();
5709                actions.borrow_mut().push(format!("{} d", view.id));
5710            }
5711        });
5712
5713        cx.capture_action({
5714            let actions = actions.clone();
5715            move |view: &mut ViewA, _: &Action, cx| {
5716                cx.propagate_action();
5717                actions.borrow_mut().push(format!("{} capture", view.id));
5718            }
5719        });
5720
5721        let observed_actions = Rc::new(RefCell::new(Vec::new()));
5722        cx.observe_actions({
5723            let observed_actions = observed_actions.clone();
5724            move |action_id, _| observed_actions.borrow_mut().push(action_id)
5725        })
5726        .detach();
5727
5728        let (window_id, view_1) =
5729            cx.add_window(Default::default(), |_| ViewA { id: 1, child: None });
5730        let view_2 = cx
5731            .update_window(window_id, |cx| {
5732                let child = cx.add_view(|_| ViewB { id: 2, child: None });
5733                view_1.update(cx, |view, cx| {
5734                    view.child = Some(child.clone().into_any());
5735                    cx.notify();
5736                });
5737                child
5738            })
5739            .unwrap();
5740        let view_3 = cx
5741            .update_window(window_id, |cx| {
5742                let child = cx.add_view(|_| ViewA { id: 3, child: None });
5743                view_2.update(cx, |view, cx| {
5744                    view.child = Some(child.clone().into_any());
5745                    cx.notify();
5746                });
5747                child
5748            })
5749            .unwrap();
5750        let view_4 = cx
5751            .update_window(window_id, |cx| {
5752                let child = cx.add_view(|_| ViewB { id: 4, child: None });
5753                view_3.update(cx, |view, cx| {
5754                    view.child = Some(child.clone().into_any());
5755                    cx.notify();
5756                });
5757                child
5758            })
5759            .unwrap();
5760
5761        cx.update_window(window_id, |cx| {
5762            cx.dispatch_action(Some(view_4.id()), &Action("bar".to_string()))
5763        });
5764
5765        assert_eq!(
5766            *actions.borrow(),
5767            vec![
5768                "1 capture",
5769                "3 capture",
5770                "4 d",
5771                "4 c",
5772                "3 b",
5773                "3 a",
5774                "2 d",
5775                "2 c",
5776                "1 b"
5777            ]
5778        );
5779        assert_eq!(*observed_actions.borrow(), [Action::default().id()]);
5780
5781        // Remove view_1, which doesn't propagate the action
5782
5783        let (window_id, view_2) =
5784            cx.add_window(Default::default(), |_| ViewB { id: 2, child: None });
5785        let view_3 = cx
5786            .update_window(window_id, |cx| {
5787                let child = cx.add_view(|_| ViewA { id: 3, child: None });
5788                view_2.update(cx, |view, cx| {
5789                    view.child = Some(child.clone().into_any());
5790                    cx.notify();
5791                });
5792                child
5793            })
5794            .unwrap();
5795        let view_4 = cx
5796            .update_window(window_id, |cx| {
5797                let child = cx.add_view(|_| ViewB { id: 4, child: None });
5798                view_3.update(cx, |view, cx| {
5799                    view.child = Some(child.clone().into_any());
5800                    cx.notify();
5801                });
5802                child
5803            })
5804            .unwrap();
5805
5806        actions.borrow_mut().clear();
5807        cx.update_window(window_id, |cx| {
5808            cx.dispatch_action(Some(view_4.id()), &Action("bar".to_string()))
5809        });
5810
5811        assert_eq!(
5812            *actions.borrow(),
5813            vec![
5814                "3 capture",
5815                "4 d",
5816                "4 c",
5817                "3 b",
5818                "3 a",
5819                "2 d",
5820                "2 c",
5821                "global"
5822            ]
5823        );
5824        assert_eq!(
5825            *observed_actions.borrow(),
5826            [Action::default().id(), Action::default().id()]
5827        );
5828    }
5829
5830    #[crate::test(self)]
5831    fn test_dispatch_keystroke(cx: &mut AppContext) {
5832        #[derive(Clone, Deserialize, PartialEq)]
5833        pub struct Action(String);
5834
5835        impl_actions!(test, [Action]);
5836
5837        struct View {
5838            id: usize,
5839            keymap_context: KeymapContext,
5840            child: Option<AnyViewHandle>,
5841        }
5842
5843        impl Entity for View {
5844            type Event = ();
5845        }
5846
5847        impl super::View for View {
5848            fn render(&mut self, cx: &mut ViewContext<Self>) -> AnyElement<Self> {
5849                self.child
5850                    .as_ref()
5851                    .map(|child| ChildView::new(child, cx).into_any())
5852                    .unwrap_or(Empty::new().into_any())
5853            }
5854
5855            fn ui_name() -> &'static str {
5856                "View"
5857            }
5858
5859            fn update_keymap_context(&self, keymap: &mut KeymapContext, _: &AppContext) {
5860                *keymap = self.keymap_context.clone();
5861            }
5862        }
5863
5864        impl View {
5865            fn new(id: usize) -> Self {
5866                View {
5867                    id,
5868                    keymap_context: KeymapContext::default(),
5869                    child: None,
5870                }
5871            }
5872        }
5873
5874        let mut view_1 = View::new(1);
5875        let mut view_2 = View::new(2);
5876        let mut view_3 = View::new(3);
5877        view_1.keymap_context.add_identifier("a");
5878        view_2.keymap_context.add_identifier("a");
5879        view_2.keymap_context.add_identifier("b");
5880        view_3.keymap_context.add_identifier("a");
5881        view_3.keymap_context.add_identifier("b");
5882        view_3.keymap_context.add_identifier("c");
5883
5884        let (window_id, _view_1) = cx.add_window(Default::default(), |cx| {
5885            let view_2 = cx.add_view(|cx| {
5886                let view_3 = cx.add_view(|cx| {
5887                    cx.focus_self();
5888                    view_3
5889                });
5890                view_2.child = Some(view_3.into_any());
5891                view_2
5892            });
5893            view_1.child = Some(view_2.into_any());
5894            view_1
5895        });
5896
5897        // This binding only dispatches an action on view 2 because that view will have
5898        // "a" and "b" in its context, but not "c".
5899        cx.add_bindings(vec![Binding::new(
5900            "a",
5901            Action("a".to_string()),
5902            Some("a && b && !c"),
5903        )]);
5904
5905        cx.add_bindings(vec![Binding::new("b", Action("b".to_string()), None)]);
5906
5907        // This binding only dispatches an action on views 2 and 3, because they have
5908        // a parent view with a in its context
5909        cx.add_bindings(vec![Binding::new(
5910            "c",
5911            Action("c".to_string()),
5912            Some("b > c"),
5913        )]);
5914
5915        // This binding only dispatches an action on view 2, because they have
5916        // a parent view with a in its context
5917        cx.add_bindings(vec![Binding::new(
5918            "d",
5919            Action("d".to_string()),
5920            Some("a && !b > b"),
5921        )]);
5922
5923        let actions = Rc::new(RefCell::new(Vec::new()));
5924        cx.add_action({
5925            let actions = actions.clone();
5926            move |view: &mut View, action: &Action, cx| {
5927                actions
5928                    .borrow_mut()
5929                    .push(format!("{} {}", view.id, action.0));
5930
5931                if action.0 == "b" {
5932                    cx.propagate_action();
5933                }
5934            }
5935        });
5936
5937        cx.add_global_action({
5938            let actions = actions.clone();
5939            move |action: &Action, _| {
5940                actions.borrow_mut().push(format!("global {}", action.0));
5941            }
5942        });
5943
5944        cx.update_window(window_id, |cx| {
5945            cx.dispatch_keystroke(&Keystroke::parse("a").unwrap())
5946        });
5947        assert_eq!(&*actions.borrow(), &["2 a"]);
5948        actions.borrow_mut().clear();
5949
5950        cx.update_window(window_id, |cx| {
5951            cx.dispatch_keystroke(&Keystroke::parse("b").unwrap());
5952        });
5953
5954        assert_eq!(&*actions.borrow(), &["3 b", "2 b", "1 b", "global b"]);
5955        actions.borrow_mut().clear();
5956
5957        cx.update_window(window_id, |cx| {
5958            cx.dispatch_keystroke(&Keystroke::parse("c").unwrap());
5959        });
5960        assert_eq!(&*actions.borrow(), &["3 c"]);
5961        actions.borrow_mut().clear();
5962
5963        cx.update_window(window_id, |cx| {
5964            cx.dispatch_keystroke(&Keystroke::parse("d").unwrap());
5965        });
5966        assert_eq!(&*actions.borrow(), &["2 d"]);
5967        actions.borrow_mut().clear();
5968    }
5969
5970    #[crate::test(self)]
5971    fn test_keystrokes_for_action(cx: &mut TestAppContext) {
5972        actions!(test, [Action1, Action2, GlobalAction]);
5973
5974        struct View1 {
5975            child: ViewHandle<View2>,
5976        }
5977        struct View2 {}
5978
5979        impl Entity for View1 {
5980            type Event = ();
5981        }
5982        impl Entity for View2 {
5983            type Event = ();
5984        }
5985
5986        impl super::View for View1 {
5987            fn render(&mut self, cx: &mut ViewContext<Self>) -> AnyElement<Self> {
5988                ChildView::new(&self.child, cx).into_any()
5989            }
5990            fn ui_name() -> &'static str {
5991                "View1"
5992            }
5993        }
5994        impl super::View for View2 {
5995            fn render(&mut self, _: &mut ViewContext<Self>) -> AnyElement<Self> {
5996                Empty::new().into_any()
5997            }
5998            fn ui_name() -> &'static str {
5999                "View2"
6000            }
6001        }
6002
6003        let (window_id, view_1) = cx.add_window(|cx| {
6004            let view_2 = cx.add_view(|cx| {
6005                cx.focus_self();
6006                View2 {}
6007            });
6008            View1 { child: view_2 }
6009        });
6010        let view_2 = view_1.read_with(cx, |view, _| view.child.clone());
6011
6012        cx.update(|cx| {
6013            cx.add_action(|_: &mut View1, _: &Action1, _cx| {});
6014            cx.add_action(|_: &mut View2, _: &Action2, _cx| {});
6015            cx.add_global_action(|_: &GlobalAction, _| {});
6016            cx.add_bindings(vec![
6017                Binding::new("a", Action1, Some("View1")),
6018                Binding::new("b", Action2, Some("View1 > View2")),
6019                Binding::new("c", GlobalAction, Some("View3")), // View 3 does not exist
6020            ]);
6021        });
6022
6023        let view_1_id = view_1.id();
6024        view_1.update(cx, |_, cx| {
6025            view_2.update(cx, |_, cx| {
6026                // Sanity check
6027                let mut new_parents = Default::default();
6028                let mut notify_views_if_parents_change = Default::default();
6029                let mut layout_cx = LayoutContext::new(
6030                    cx,
6031                    &mut new_parents,
6032                    &mut notify_views_if_parents_change,
6033                    false,
6034                );
6035                assert_eq!(
6036                    layout_cx
6037                        .keystrokes_for_action(view_1_id, &Action1)
6038                        .unwrap()
6039                        .as_slice(),
6040                    &[Keystroke::parse("a").unwrap()]
6041                );
6042                assert_eq!(
6043                    layout_cx
6044                        .keystrokes_for_action(view_2.id(), &Action2)
6045                        .unwrap()
6046                        .as_slice(),
6047                    &[Keystroke::parse("b").unwrap()]
6048                );
6049
6050                // The 'a' keystroke propagates up the view tree from view_2
6051                // to view_1. The action, Action1, is handled by view_1.
6052                assert_eq!(
6053                    layout_cx
6054                        .keystrokes_for_action(view_2.id(), &Action1)
6055                        .unwrap()
6056                        .as_slice(),
6057                    &[Keystroke::parse("a").unwrap()]
6058                );
6059
6060                // Actions that are handled below the current view don't have bindings
6061                assert_eq!(layout_cx.keystrokes_for_action(view_1_id, &Action2), None);
6062
6063                // Actions that are handled in other branches of the tree should not have a binding
6064                assert_eq!(
6065                    layout_cx.keystrokes_for_action(view_2.id(), &GlobalAction),
6066                    None
6067                );
6068            });
6069        });
6070
6071        // Check that global actions do not have a binding, even if a binding does exist in another view
6072        assert_eq!(
6073            &available_actions(window_id, view_1.id(), cx),
6074            &[
6075                ("test::Action1", vec![Keystroke::parse("a").unwrap()]),
6076                ("test::GlobalAction", vec![])
6077            ],
6078        );
6079
6080        // Check that view 1 actions and bindings are available even when called from view 2
6081        assert_eq!(
6082            &available_actions(window_id, view_2.id(), cx),
6083            &[
6084                ("test::Action1", vec![Keystroke::parse("a").unwrap()]),
6085                ("test::Action2", vec![Keystroke::parse("b").unwrap()]),
6086                ("test::GlobalAction", vec![]),
6087            ],
6088        );
6089
6090        // Produces a list of actions and key bindings
6091        fn available_actions(
6092            window_id: usize,
6093            view_id: usize,
6094            cx: &TestAppContext,
6095        ) -> Vec<(&'static str, Vec<Keystroke>)> {
6096            cx.available_actions(window_id, view_id)
6097                .into_iter()
6098                .map(|(action_name, _, bindings)| {
6099                    (
6100                        action_name,
6101                        bindings
6102                            .iter()
6103                            .map(|binding| binding.keystrokes()[0].clone())
6104                            .collect::<Vec<_>>(),
6105                    )
6106                })
6107                .sorted_by(|(name1, _), (name2, _)| name1.cmp(name2))
6108                .collect()
6109        }
6110    }
6111
6112    #[crate::test(self)]
6113    fn test_keystrokes_for_action_with_data(cx: &mut TestAppContext) {
6114        #[derive(Clone, Debug, Deserialize, PartialEq)]
6115        struct ActionWithArg {
6116            #[serde(default)]
6117            arg: bool,
6118        }
6119
6120        struct View;
6121        impl super::Entity for View {
6122            type Event = ();
6123        }
6124        impl super::View for View {
6125            fn render(&mut self, _: &mut ViewContext<Self>) -> AnyElement<Self> {
6126                Empty::new().into_any()
6127            }
6128            fn ui_name() -> &'static str {
6129                "View"
6130            }
6131        }
6132
6133        impl_actions!(test, [ActionWithArg]);
6134
6135        let (window_id, view) = cx.add_window(|_| View);
6136        cx.update(|cx| {
6137            cx.add_global_action(|_: &ActionWithArg, _| {});
6138            cx.add_bindings(vec![
6139                Binding::new("a", ActionWithArg { arg: false }, None),
6140                Binding::new("shift-a", ActionWithArg { arg: true }, None),
6141            ]);
6142        });
6143
6144        let actions = cx.available_actions(window_id, view.id());
6145        assert_eq!(
6146            actions[0].1.as_any().downcast_ref::<ActionWithArg>(),
6147            Some(&ActionWithArg { arg: false })
6148        );
6149        assert_eq!(
6150            actions[0]
6151                .2
6152                .iter()
6153                .map(|b| b.keystrokes()[0].clone())
6154                .collect::<Vec<_>>(),
6155            vec![Keystroke::parse("a").unwrap()],
6156        );
6157    }
6158
6159    #[crate::test(self)]
6160    async fn test_model_condition(cx: &mut TestAppContext) {
6161        struct Counter(usize);
6162
6163        impl super::Entity for Counter {
6164            type Event = ();
6165        }
6166
6167        impl Counter {
6168            fn inc(&mut self, cx: &mut ModelContext<Self>) {
6169                self.0 += 1;
6170                cx.notify();
6171            }
6172        }
6173
6174        let model = cx.add_model(|_| Counter(0));
6175
6176        let condition1 = model.condition(cx, |model, _| model.0 == 2);
6177        let condition2 = model.condition(cx, |model, _| model.0 == 3);
6178        smol::pin!(condition1, condition2);
6179
6180        model.update(cx, |model, cx| model.inc(cx));
6181        assert_eq!(poll_once(&mut condition1).await, None);
6182        assert_eq!(poll_once(&mut condition2).await, None);
6183
6184        model.update(cx, |model, cx| model.inc(cx));
6185        assert_eq!(poll_once(&mut condition1).await, Some(()));
6186        assert_eq!(poll_once(&mut condition2).await, None);
6187
6188        model.update(cx, |model, cx| model.inc(cx));
6189        assert_eq!(poll_once(&mut condition2).await, Some(()));
6190
6191        model.update(cx, |_, cx| cx.notify());
6192    }
6193
6194    #[crate::test(self)]
6195    #[should_panic]
6196    async fn test_model_condition_timeout(cx: &mut TestAppContext) {
6197        struct Model;
6198
6199        impl super::Entity for Model {
6200            type Event = ();
6201        }
6202
6203        let model = cx.add_model(|_| Model);
6204        model.condition(cx, |_, _| false).await;
6205    }
6206
6207    #[crate::test(self)]
6208    #[should_panic(expected = "model dropped with pending condition")]
6209    async fn test_model_condition_panic_on_drop(cx: &mut TestAppContext) {
6210        struct Model;
6211
6212        impl super::Entity for Model {
6213            type Event = ();
6214        }
6215
6216        let model = cx.add_model(|_| Model);
6217        let condition = model.condition(cx, |_, _| false);
6218        cx.update(|_| drop(model));
6219        condition.await;
6220    }
6221
6222    #[crate::test(self)]
6223    async fn test_view_condition(cx: &mut TestAppContext) {
6224        struct Counter(usize);
6225
6226        impl super::Entity for Counter {
6227            type Event = ();
6228        }
6229
6230        impl super::View for Counter {
6231            fn ui_name() -> &'static str {
6232                "test view"
6233            }
6234
6235            fn render(&mut self, _: &mut ViewContext<Self>) -> AnyElement<Self> {
6236                Empty::new().into_any()
6237            }
6238        }
6239
6240        impl Counter {
6241            fn inc(&mut self, cx: &mut ViewContext<Self>) {
6242                self.0 += 1;
6243                cx.notify();
6244            }
6245        }
6246
6247        let (_, view) = cx.add_window(|_| Counter(0));
6248
6249        let condition1 = view.condition(cx, |view, _| view.0 == 2);
6250        let condition2 = view.condition(cx, |view, _| view.0 == 3);
6251        smol::pin!(condition1, condition2);
6252
6253        view.update(cx, |view, cx| view.inc(cx));
6254        assert_eq!(poll_once(&mut condition1).await, None);
6255        assert_eq!(poll_once(&mut condition2).await, None);
6256
6257        view.update(cx, |view, cx| view.inc(cx));
6258        assert_eq!(poll_once(&mut condition1).await, Some(()));
6259        assert_eq!(poll_once(&mut condition2).await, None);
6260
6261        view.update(cx, |view, cx| view.inc(cx));
6262        assert_eq!(poll_once(&mut condition2).await, Some(()));
6263        view.update(cx, |_, cx| cx.notify());
6264    }
6265
6266    #[crate::test(self)]
6267    #[should_panic]
6268    async fn test_view_condition_timeout(cx: &mut TestAppContext) {
6269        let (_, view) = cx.add_window(|_| TestView::default());
6270        view.condition(cx, |_, _| false).await;
6271    }
6272
6273    #[crate::test(self)]
6274    #[should_panic(expected = "view dropped with pending condition")]
6275    async fn test_view_condition_panic_on_drop(cx: &mut TestAppContext) {
6276        let (window_id, _root_view) = cx.add_window(|_| TestView::default());
6277        let view = cx.add_view(window_id, |_| TestView::default());
6278
6279        let condition = view.condition(cx, |_, _| false);
6280        cx.update(|_| drop(view));
6281        condition.await;
6282    }
6283
6284    #[crate::test(self)]
6285    fn test_refresh_windows(cx: &mut AppContext) {
6286        struct View(usize);
6287
6288        impl super::Entity for View {
6289            type Event = ();
6290        }
6291
6292        impl super::View for View {
6293            fn ui_name() -> &'static str {
6294                "test view"
6295            }
6296
6297            fn render(&mut self, _: &mut ViewContext<Self>) -> AnyElement<Self> {
6298                Empty::new().into_any_named(format!("render count: {}", post_inc(&mut self.0)))
6299            }
6300        }
6301
6302        let (window_id, root_view) = cx.add_window(Default::default(), |_| View(0));
6303        cx.update_window(window_id, |cx| {
6304            assert_eq!(
6305                cx.window.rendered_views[&root_view.id()].name(),
6306                Some("render count: 0")
6307            );
6308        });
6309
6310        let view = cx
6311            .update_window(window_id, |cx| {
6312                cx.refresh_windows();
6313                cx.add_view(|_| View(0))
6314            })
6315            .unwrap();
6316
6317        cx.update_window(window_id, |cx| {
6318            assert_eq!(
6319                cx.window.rendered_views[&root_view.id()].name(),
6320                Some("render count: 1")
6321            );
6322            assert_eq!(
6323                cx.window.rendered_views[&view.id()].name(),
6324                Some("render count: 0")
6325            );
6326        });
6327
6328        cx.update(|cx| cx.refresh_windows());
6329
6330        cx.update_window(window_id, |cx| {
6331            assert_eq!(
6332                cx.window.rendered_views[&root_view.id()].name(),
6333                Some("render count: 2")
6334            );
6335            assert_eq!(
6336                cx.window.rendered_views[&view.id()].name(),
6337                Some("render count: 1")
6338            );
6339        });
6340
6341        cx.update(|cx| {
6342            cx.refresh_windows();
6343            drop(view);
6344        });
6345
6346        cx.update_window(window_id, |cx| {
6347            assert_eq!(
6348                cx.window.rendered_views[&root_view.id()].name(),
6349                Some("render count: 3")
6350            );
6351            assert_eq!(cx.window.rendered_views.len(), 1);
6352        });
6353    }
6354
6355    #[crate::test(self)]
6356    async fn test_labeled_tasks(cx: &mut TestAppContext) {
6357        assert_eq!(None, cx.update(|cx| cx.active_labeled_tasks().next()));
6358        let (mut sender, mut receiver) = postage::oneshot::channel::<()>();
6359        let task = cx
6360            .update(|cx| cx.spawn_labeled("Test Label", |_| async move { receiver.recv().await }));
6361
6362        assert_eq!(
6363            Some("Test Label"),
6364            cx.update(|cx| cx.active_labeled_tasks().next())
6365        );
6366        sender
6367            .send(())
6368            .await
6369            .expect("Could not send message to complete task");
6370        task.await;
6371
6372        assert_eq!(None, cx.update(|cx| cx.active_labeled_tasks().next()));
6373    }
6374
6375    #[crate::test(self)]
6376    async fn test_window_activation(cx: &mut TestAppContext) {
6377        struct View(&'static str);
6378
6379        impl super::Entity for View {
6380            type Event = ();
6381        }
6382
6383        impl super::View for View {
6384            fn ui_name() -> &'static str {
6385                "test view"
6386            }
6387
6388            fn render(&mut self, _: &mut ViewContext<Self>) -> AnyElement<Self> {
6389                Empty::new().into_any()
6390            }
6391        }
6392
6393        let events = Rc::new(RefCell::new(Vec::new()));
6394        let (window_1, _) = cx.add_window(|cx: &mut ViewContext<View>| {
6395            cx.observe_window_activation({
6396                let events = events.clone();
6397                move |this, active, _| events.borrow_mut().push((this.0, active))
6398            })
6399            .detach();
6400            View("window 1")
6401        });
6402        assert_eq!(mem::take(&mut *events.borrow_mut()), [("window 1", true)]);
6403
6404        let (window_2, _) = cx.add_window(|cx: &mut ViewContext<View>| {
6405            cx.observe_window_activation({
6406                let events = events.clone();
6407                move |this, active, _| events.borrow_mut().push((this.0, active))
6408            })
6409            .detach();
6410            View("window 2")
6411        });
6412        assert_eq!(
6413            mem::take(&mut *events.borrow_mut()),
6414            [("window 1", false), ("window 2", true)]
6415        );
6416
6417        let (window_3, _) = cx.add_window(|cx: &mut ViewContext<View>| {
6418            cx.observe_window_activation({
6419                let events = events.clone();
6420                move |this, active, _| events.borrow_mut().push((this.0, active))
6421            })
6422            .detach();
6423            View("window 3")
6424        });
6425        assert_eq!(
6426            mem::take(&mut *events.borrow_mut()),
6427            [("window 2", false), ("window 3", true)]
6428        );
6429
6430        cx.simulate_window_activation(Some(window_2));
6431        assert_eq!(
6432            mem::take(&mut *events.borrow_mut()),
6433            [("window 3", false), ("window 2", true)]
6434        );
6435
6436        cx.simulate_window_activation(Some(window_1));
6437        assert_eq!(
6438            mem::take(&mut *events.borrow_mut()),
6439            [("window 2", false), ("window 1", true)]
6440        );
6441
6442        cx.simulate_window_activation(Some(window_3));
6443        assert_eq!(
6444            mem::take(&mut *events.borrow_mut()),
6445            [("window 1", false), ("window 3", true)]
6446        );
6447
6448        cx.simulate_window_activation(Some(window_3));
6449        assert_eq!(mem::take(&mut *events.borrow_mut()), []);
6450    }
6451
6452    #[crate::test(self)]
6453    fn test_child_view(cx: &mut TestAppContext) {
6454        struct Child {
6455            rendered: Rc<Cell<bool>>,
6456            dropped: Rc<Cell<bool>>,
6457        }
6458
6459        impl super::Entity for Child {
6460            type Event = ();
6461        }
6462
6463        impl super::View for Child {
6464            fn ui_name() -> &'static str {
6465                "child view"
6466            }
6467
6468            fn render(&mut self, _: &mut ViewContext<Self>) -> AnyElement<Self> {
6469                self.rendered.set(true);
6470                Empty::new().into_any()
6471            }
6472        }
6473
6474        impl Drop for Child {
6475            fn drop(&mut self) {
6476                self.dropped.set(true);
6477            }
6478        }
6479
6480        struct Parent {
6481            child: Option<ViewHandle<Child>>,
6482        }
6483
6484        impl super::Entity for Parent {
6485            type Event = ();
6486        }
6487
6488        impl super::View for Parent {
6489            fn ui_name() -> &'static str {
6490                "parent view"
6491            }
6492
6493            fn render(&mut self, cx: &mut ViewContext<Self>) -> AnyElement<Self> {
6494                if let Some(child) = self.child.as_ref() {
6495                    ChildView::new(child, cx).into_any()
6496                } else {
6497                    Empty::new().into_any()
6498                }
6499            }
6500        }
6501
6502        let child_rendered = Rc::new(Cell::new(false));
6503        let child_dropped = Rc::new(Cell::new(false));
6504        let (_, root_view) = cx.add_window(|cx| Parent {
6505            child: Some(cx.add_view(|_| Child {
6506                rendered: child_rendered.clone(),
6507                dropped: child_dropped.clone(),
6508            })),
6509        });
6510        assert!(child_rendered.take());
6511        assert!(!child_dropped.take());
6512
6513        root_view.update(cx, |view, cx| {
6514            view.child.take();
6515            cx.notify();
6516        });
6517        assert!(!child_rendered.take());
6518        assert!(child_dropped.take());
6519    }
6520
6521    #[derive(Default)]
6522    struct TestView {
6523        events: Vec<String>,
6524    }
6525
6526    impl Entity for TestView {
6527        type Event = String;
6528    }
6529
6530    impl View for TestView {
6531        fn ui_name() -> &'static str {
6532            "TestView"
6533        }
6534
6535        fn render(&mut self, _: &mut ViewContext<Self>) -> AnyElement<Self> {
6536            Empty::new().into_any()
6537        }
6538    }
6539}