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