app.rs

   1use crate::{
   2    elements::ElementBox,
   3    executor,
   4    keymap::{self, Keystroke},
   5    platform::{self, Platform, PromptLevel, WindowOptions},
   6    presenter::Presenter,
   7    util::{post_inc, timeout},
   8    AssetCache, AssetSource, ClipboardItem, FontCache, PathPromptOptions, TextLayoutCache,
   9};
  10use anyhow::{anyhow, Result};
  11use async_task::Task;
  12use keymap::MatchResult;
  13use parking_lot::{Mutex, RwLock};
  14use pathfinder_geometry::{rect::RectF, vector::vec2f};
  15use platform::Event;
  16use postage::{mpsc, sink::Sink as _, stream::Stream as _};
  17use smol::prelude::*;
  18use std::{
  19    any::{type_name, Any, TypeId},
  20    cell::RefCell,
  21    collections::{hash_map::Entry, HashMap, HashSet, VecDeque},
  22    fmt::{self, Debug},
  23    hash::{Hash, Hasher},
  24    marker::PhantomData,
  25    path::{Path, PathBuf},
  26    rc::{self, Rc},
  27    sync::{Arc, Weak},
  28    time::Duration,
  29};
  30
  31pub trait Entity: 'static + Send + Sync {
  32    type Event;
  33
  34    fn release(&mut self, _: &mut MutableAppContext) {}
  35}
  36
  37pub trait View: Entity {
  38    fn ui_name() -> &'static str;
  39    fn render<'a>(&self, cx: &AppContext) -> ElementBox;
  40    fn on_focus(&mut self, _: &mut ViewContext<Self>) {}
  41    fn on_blur(&mut self, _: &mut ViewContext<Self>) {}
  42    fn keymap_context(&self, _: &AppContext) -> keymap::Context {
  43        Self::default_keymap_context()
  44    }
  45    fn default_keymap_context() -> keymap::Context {
  46        let mut cx = keymap::Context::default();
  47        cx.set.insert(Self::ui_name().into());
  48        cx
  49    }
  50}
  51
  52pub trait ReadModel {
  53    fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T;
  54}
  55
  56pub trait ReadModelWith {
  57    fn read_model_with<E: Entity, F: FnOnce(&E, &AppContext) -> T, T>(
  58        &self,
  59        handle: &ModelHandle<E>,
  60        read: F,
  61    ) -> T;
  62}
  63
  64pub trait UpdateModel {
  65    fn update_model<T, F, S>(&mut self, handle: &ModelHandle<T>, update: F) -> S
  66    where
  67        T: Entity,
  68        F: FnOnce(&mut T, &mut ModelContext<T>) -> S;
  69}
  70
  71pub trait ReadView {
  72    fn read_view<T: View>(&self, handle: &ViewHandle<T>) -> &T;
  73}
  74
  75pub trait ReadViewWith {
  76    fn read_view_with<V, F, T>(&self, handle: &ViewHandle<V>, read: F) -> T
  77    where
  78        V: View,
  79        F: FnOnce(&V, &AppContext) -> T;
  80}
  81
  82pub trait UpdateView {
  83    fn update_view<T, F, S>(&mut self, handle: &ViewHandle<T>, update: F) -> S
  84    where
  85        T: View,
  86        F: FnOnce(&mut T, &mut ViewContext<T>) -> S;
  87}
  88
  89pub struct Menu<'a> {
  90    pub name: &'a str,
  91    pub items: Vec<MenuItem<'a>>,
  92}
  93
  94pub enum MenuItem<'a> {
  95    Action {
  96        name: &'a str,
  97        keystroke: Option<&'a str>,
  98        action: &'a str,
  99        arg: Option<Box<dyn Any + 'static>>,
 100    },
 101    Separator,
 102}
 103
 104#[derive(Clone)]
 105pub struct App(Rc<RefCell<MutableAppContext>>);
 106
 107#[derive(Clone)]
 108pub struct AsyncAppContext(Rc<RefCell<MutableAppContext>>);
 109
 110pub struct BackgroundAppContext(*const RefCell<MutableAppContext>);
 111
 112#[derive(Clone)]
 113pub struct TestAppContext {
 114    cx: Rc<RefCell<MutableAppContext>>,
 115    foreground_platform: Rc<platform::test::ForegroundPlatform>,
 116}
 117
 118impl App {
 119    pub fn test<T, F: FnOnce(&mut MutableAppContext) -> T>(f: F) -> T {
 120        let foreground_platform = platform::test::foreground_platform();
 121        let platform = platform::test::platform();
 122        let foreground = Rc::new(executor::Foreground::test());
 123        let cx = Rc::new(RefCell::new(MutableAppContext::new(
 124            foreground,
 125            Arc::new(executor::Background::new()),
 126            Arc::new(platform),
 127            Rc::new(foreground_platform),
 128            (),
 129        )));
 130        cx.borrow_mut().weak_self = Some(Rc::downgrade(&cx));
 131        let mut cx = cx.borrow_mut();
 132        f(&mut *cx)
 133    }
 134
 135    pub fn new(asset_source: impl AssetSource) -> Result<Self> {
 136        let platform = platform::current::platform();
 137        let foreground_platform = platform::current::foreground_platform();
 138        let foreground = Rc::new(executor::Foreground::platform(platform.dispatcher())?);
 139        let app = Self(Rc::new(RefCell::new(MutableAppContext::new(
 140            foreground,
 141            Arc::new(executor::Background::new()),
 142            platform.clone(),
 143            foreground_platform.clone(),
 144            asset_source,
 145        ))));
 146
 147        let cx = app.0.clone();
 148        foreground_platform.on_menu_command(Box::new(move |command, arg| {
 149            let mut cx = cx.borrow_mut();
 150            if let Some(key_window_id) = cx.platform.key_window_id() {
 151                if let Some((presenter, _)) = cx.presenters_and_platform_windows.get(&key_window_id)
 152                {
 153                    let presenter = presenter.clone();
 154                    let path = presenter.borrow().dispatch_path(cx.as_ref());
 155                    cx.dispatch_action_any(key_window_id, &path, command, arg.unwrap_or(&()));
 156                } else {
 157                    cx.dispatch_global_action_any(command, arg.unwrap_or(&()));
 158                }
 159            } else {
 160                cx.dispatch_global_action_any(command, arg.unwrap_or(&()));
 161            }
 162        }));
 163
 164        app.0.borrow_mut().weak_self = Some(Rc::downgrade(&app.0));
 165        Ok(app)
 166    }
 167
 168    pub fn on_become_active<F>(self, mut callback: F) -> Self
 169    where
 170        F: 'static + FnMut(&mut MutableAppContext),
 171    {
 172        let cx = self.0.clone();
 173        self.0
 174            .borrow_mut()
 175            .foreground_platform
 176            .on_become_active(Box::new(move || callback(&mut *cx.borrow_mut())));
 177        self
 178    }
 179
 180    pub fn on_resign_active<F>(self, mut callback: F) -> Self
 181    where
 182        F: 'static + FnMut(&mut MutableAppContext),
 183    {
 184        let cx = self.0.clone();
 185        self.0
 186            .borrow_mut()
 187            .foreground_platform
 188            .on_resign_active(Box::new(move || callback(&mut *cx.borrow_mut())));
 189        self
 190    }
 191
 192    pub fn on_event<F>(self, mut callback: F) -> Self
 193    where
 194        F: 'static + FnMut(Event, &mut MutableAppContext) -> bool,
 195    {
 196        let cx = self.0.clone();
 197        self.0
 198            .borrow_mut()
 199            .foreground_platform
 200            .on_event(Box::new(move |event| {
 201                callback(event, &mut *cx.borrow_mut())
 202            }));
 203        self
 204    }
 205
 206    pub fn on_open_files<F>(self, mut callback: F) -> Self
 207    where
 208        F: 'static + FnMut(Vec<PathBuf>, &mut MutableAppContext),
 209    {
 210        let cx = self.0.clone();
 211        self.0
 212            .borrow_mut()
 213            .foreground_platform
 214            .on_open_files(Box::new(move |paths| {
 215                callback(paths, &mut *cx.borrow_mut())
 216            }));
 217        self
 218    }
 219
 220    pub fn run<F>(self, on_finish_launching: F)
 221    where
 222        F: 'static + FnOnce(&mut MutableAppContext),
 223    {
 224        let platform = self.0.borrow().foreground_platform.clone();
 225        platform.run(Box::new(move || {
 226            let mut cx = self.0.borrow_mut();
 227            on_finish_launching(&mut *cx);
 228        }))
 229    }
 230
 231    pub fn font_cache(&self) -> Arc<FontCache> {
 232        self.0.borrow().cx.font_cache.clone()
 233    }
 234
 235    fn update<T, F: FnOnce(&mut MutableAppContext) -> T>(&mut self, callback: F) -> T {
 236        let mut state = self.0.borrow_mut();
 237        state.pending_flushes += 1;
 238        let result = callback(&mut *state);
 239        state.flush_effects();
 240        result
 241    }
 242}
 243
 244impl TestAppContext {
 245    pub fn new(
 246        foreground: Rc<executor::Foreground>,
 247        background: Arc<executor::Background>,
 248        first_entity_id: usize,
 249    ) -> Self {
 250        let platform = Arc::new(platform::test::platform());
 251        let foreground_platform = Rc::new(platform::test::foreground_platform());
 252        let mut cx = MutableAppContext::new(
 253            foreground.clone(),
 254            background,
 255            platform,
 256            foreground_platform.clone(),
 257            (),
 258        );
 259        cx.next_entity_id = first_entity_id;
 260        let cx = TestAppContext {
 261            cx: Rc::new(RefCell::new(cx)),
 262            foreground_platform,
 263        };
 264        cx.cx.borrow_mut().weak_self = Some(Rc::downgrade(&cx.cx));
 265        cx
 266    }
 267
 268    pub fn dispatch_action<T: 'static + Any>(
 269        &self,
 270        window_id: usize,
 271        responder_chain: Vec<usize>,
 272        name: &str,
 273        arg: T,
 274    ) {
 275        self.cx.borrow_mut().dispatch_action_any(
 276            window_id,
 277            &responder_chain,
 278            name,
 279            Box::new(arg).as_ref(),
 280        );
 281    }
 282
 283    pub fn dispatch_global_action<T: 'static + Any>(&self, name: &str, arg: T) {
 284        self.cx.borrow_mut().dispatch_global_action(name, arg);
 285    }
 286
 287    pub fn dispatch_keystroke(
 288        &self,
 289        window_id: usize,
 290        responder_chain: Vec<usize>,
 291        keystroke: &Keystroke,
 292    ) -> Result<bool> {
 293        let mut state = self.cx.borrow_mut();
 294        state.dispatch_keystroke(window_id, responder_chain, keystroke)
 295    }
 296
 297    pub fn add_model<T, F>(&mut self, build_model: F) -> ModelHandle<T>
 298    where
 299        T: Entity,
 300        F: FnOnce(&mut ModelContext<T>) -> T,
 301    {
 302        let mut state = self.cx.borrow_mut();
 303        state.pending_flushes += 1;
 304        let handle = state.add_model(build_model);
 305        state.flush_effects();
 306        handle
 307    }
 308
 309    pub fn add_window<T, F>(&mut self, build_root_view: F) -> (usize, ViewHandle<T>)
 310    where
 311        T: View,
 312        F: FnOnce(&mut ViewContext<T>) -> T,
 313    {
 314        self.cx.borrow_mut().add_window(build_root_view)
 315    }
 316
 317    pub fn window_ids(&self) -> Vec<usize> {
 318        self.cx.borrow().window_ids().collect()
 319    }
 320
 321    pub fn root_view<T: View>(&self, window_id: usize) -> Option<ViewHandle<T>> {
 322        self.cx.borrow().root_view(window_id)
 323    }
 324
 325    pub fn add_view<T, F>(&mut self, window_id: usize, build_view: F) -> ViewHandle<T>
 326    where
 327        T: View,
 328        F: FnOnce(&mut ViewContext<T>) -> T,
 329    {
 330        let mut state = self.cx.borrow_mut();
 331        state.pending_flushes += 1;
 332        let handle = state.add_view(window_id, build_view);
 333        state.flush_effects();
 334        handle
 335    }
 336
 337    pub fn add_option_view<T, F>(
 338        &mut self,
 339        window_id: usize,
 340        build_view: F,
 341    ) -> Option<ViewHandle<T>>
 342    where
 343        T: View,
 344        F: FnOnce(&mut ViewContext<T>) -> Option<T>,
 345    {
 346        let mut state = self.cx.borrow_mut();
 347        state.pending_flushes += 1;
 348        let handle = state.add_option_view(window_id, build_view);
 349        state.flush_effects();
 350        handle
 351    }
 352
 353    pub fn read<T, F: FnOnce(&AppContext) -> T>(&self, callback: F) -> T {
 354        callback(self.cx.borrow().as_ref())
 355    }
 356
 357    pub fn update<T, F: FnOnce(&mut MutableAppContext) -> T>(&mut self, callback: F) -> T {
 358        let mut state = self.cx.borrow_mut();
 359        // Don't increment pending flushes in order to effects to be flushed before the callback
 360        // completes, which is helpful in tests.
 361        let result = callback(&mut *state);
 362        // Flush effects after the callback just in case there are any. This can happen in edge
 363        // cases such as the closure dropping handles.
 364        state.flush_effects();
 365        result
 366    }
 367
 368    pub fn to_async(&self) -> AsyncAppContext {
 369        AsyncAppContext(self.cx.clone())
 370    }
 371
 372    pub fn font_cache(&self) -> Arc<FontCache> {
 373        self.cx.borrow().cx.font_cache.clone()
 374    }
 375
 376    pub fn platform(&self) -> Arc<dyn platform::Platform> {
 377        self.cx.borrow().platform.clone()
 378    }
 379
 380    pub fn foreground(&self) -> Rc<executor::Foreground> {
 381        self.cx.borrow().foreground().clone()
 382    }
 383
 384    pub fn background(&self) -> Arc<executor::Background> {
 385        self.cx.borrow().background().clone()
 386    }
 387
 388    pub fn simulate_new_path_selection(&self, result: impl FnOnce(PathBuf) -> Option<PathBuf>) {
 389        self.foreground_platform.simulate_new_path_selection(result);
 390    }
 391
 392    pub fn did_prompt_for_new_path(&self) -> bool {
 393        self.foreground_platform.as_ref().did_prompt_for_new_path()
 394    }
 395
 396    pub fn simulate_prompt_answer(&self, window_id: usize, answer: usize) {
 397        let mut state = self.cx.borrow_mut();
 398        let (_, window) = state
 399            .presenters_and_platform_windows
 400            .get_mut(&window_id)
 401            .unwrap();
 402        let test_window = window
 403            .as_any_mut()
 404            .downcast_mut::<platform::test::Window>()
 405            .unwrap();
 406        let callback = test_window
 407            .last_prompt
 408            .take()
 409            .expect("prompt was not called");
 410        (callback)(answer);
 411    }
 412}
 413
 414impl AsyncAppContext {
 415    pub fn spawn<F, Fut, T>(&self, f: F) -> Task<T>
 416    where
 417        F: FnOnce(AsyncAppContext) -> Fut,
 418        Fut: 'static + Future<Output = T>,
 419        T: 'static,
 420    {
 421        self.0.borrow().foreground.spawn(f(self.clone()))
 422    }
 423
 424    pub fn read<T, F: FnOnce(&AppContext) -> T>(&mut self, callback: F) -> T {
 425        callback(self.0.borrow().as_ref())
 426    }
 427
 428    pub fn update<T, F: FnOnce(&mut MutableAppContext) -> T>(&mut self, callback: F) -> T {
 429        let mut state = self.0.borrow_mut();
 430        state.pending_flushes += 1;
 431        let result = callback(&mut *state);
 432        state.flush_effects();
 433        result
 434    }
 435
 436    pub fn add_model<T, F>(&mut self, build_model: F) -> ModelHandle<T>
 437    where
 438        T: Entity,
 439        F: FnOnce(&mut ModelContext<T>) -> T,
 440    {
 441        self.update(|cx| cx.add_model(build_model))
 442    }
 443
 444    pub fn platform(&self) -> Arc<dyn Platform> {
 445        self.0.borrow().platform()
 446    }
 447
 448    pub fn foreground(&self) -> Rc<executor::Foreground> {
 449        self.0.borrow().foreground.clone()
 450    }
 451
 452    pub fn background(&self) -> Arc<executor::Background> {
 453        self.0.borrow().cx.background.clone()
 454    }
 455}
 456
 457impl UpdateModel for AsyncAppContext {
 458    fn update_model<T, F, S>(&mut self, handle: &ModelHandle<T>, update: F) -> S
 459    where
 460        T: Entity,
 461        F: FnOnce(&mut T, &mut ModelContext<T>) -> S,
 462    {
 463        let mut state = self.0.borrow_mut();
 464        state.pending_flushes += 1;
 465        let result = state.update_model(handle, update);
 466        state.flush_effects();
 467        result
 468    }
 469}
 470
 471impl ReadModelWith for AsyncAppContext {
 472    fn read_model_with<E: Entity, F: FnOnce(&E, &AppContext) -> T, T>(
 473        &self,
 474        handle: &ModelHandle<E>,
 475        read: F,
 476    ) -> T {
 477        let cx = self.0.borrow();
 478        let cx = cx.as_ref();
 479        read(handle.read(cx), cx)
 480    }
 481}
 482
 483impl UpdateView for AsyncAppContext {
 484    fn update_view<T, F, S>(&mut self, handle: &ViewHandle<T>, update: F) -> S
 485    where
 486        T: View,
 487        F: FnOnce(&mut T, &mut ViewContext<T>) -> S,
 488    {
 489        let mut state = self.0.borrow_mut();
 490        state.pending_flushes += 1;
 491        let result = state.update_view(handle, update);
 492        state.flush_effects();
 493        result
 494    }
 495}
 496
 497impl ReadViewWith for AsyncAppContext {
 498    fn read_view_with<V, F, T>(&self, handle: &ViewHandle<V>, read: F) -> T
 499    where
 500        V: View,
 501        F: FnOnce(&V, &AppContext) -> T,
 502    {
 503        let cx = self.0.borrow();
 504        let cx = cx.as_ref();
 505        read(handle.read(cx), cx)
 506    }
 507}
 508
 509impl UpdateModel for TestAppContext {
 510    fn update_model<T, F, S>(&mut self, handle: &ModelHandle<T>, update: F) -> S
 511    where
 512        T: Entity,
 513        F: FnOnce(&mut T, &mut ModelContext<T>) -> S,
 514    {
 515        let mut state = self.cx.borrow_mut();
 516        state.pending_flushes += 1;
 517        let result = state.update_model(handle, update);
 518        state.flush_effects();
 519        result
 520    }
 521}
 522
 523impl ReadModelWith for TestAppContext {
 524    fn read_model_with<E: Entity, F: FnOnce(&E, &AppContext) -> T, T>(
 525        &self,
 526        handle: &ModelHandle<E>,
 527        read: F,
 528    ) -> T {
 529        let cx = self.cx.borrow();
 530        let cx = cx.as_ref();
 531        read(handle.read(cx), cx)
 532    }
 533}
 534
 535impl UpdateView for TestAppContext {
 536    fn update_view<T, F, S>(&mut self, handle: &ViewHandle<T>, update: F) -> S
 537    where
 538        T: View,
 539        F: FnOnce(&mut T, &mut ViewContext<T>) -> S,
 540    {
 541        let mut state = self.cx.borrow_mut();
 542        state.pending_flushes += 1;
 543        let result = state.update_view(handle, update);
 544        state.flush_effects();
 545        result
 546    }
 547}
 548
 549impl ReadViewWith for TestAppContext {
 550    fn read_view_with<V, F, T>(&self, handle: &ViewHandle<V>, read: F) -> T
 551    where
 552        V: View,
 553        F: FnOnce(&V, &AppContext) -> T,
 554    {
 555        let cx = self.cx.borrow();
 556        let cx = cx.as_ref();
 557        read(handle.read(cx), cx)
 558    }
 559}
 560
 561type ActionCallback =
 562    dyn FnMut(&mut dyn AnyView, &dyn Any, &mut MutableAppContext, usize, usize) -> bool;
 563
 564type GlobalActionCallback = dyn FnMut(&dyn Any, &mut MutableAppContext);
 565
 566pub struct MutableAppContext {
 567    weak_self: Option<rc::Weak<RefCell<Self>>>,
 568    foreground_platform: Rc<dyn platform::ForegroundPlatform>,
 569    platform: Arc<dyn platform::Platform>,
 570    assets: Arc<AssetCache>,
 571    cx: AppContext,
 572    actions: HashMap<TypeId, HashMap<String, Vec<Box<ActionCallback>>>>,
 573    global_actions: HashMap<String, Vec<Box<GlobalActionCallback>>>,
 574    keystroke_matcher: keymap::Matcher,
 575    next_entity_id: usize,
 576    next_window_id: usize,
 577    subscriptions: HashMap<usize, Vec<Subscription>>,
 578    model_observations: HashMap<usize, Vec<ModelObservation>>,
 579    view_observations: HashMap<usize, Vec<ViewObservation>>,
 580    presenters_and_platform_windows:
 581        HashMap<usize, (Rc<RefCell<Presenter>>, Box<dyn platform::Window>)>,
 582    debug_elements_callbacks: HashMap<usize, Box<dyn Fn(&AppContext) -> crate::json::Value>>,
 583    foreground: Rc<executor::Foreground>,
 584    pending_effects: VecDeque<Effect>,
 585    pending_flushes: usize,
 586    flushing_effects: bool,
 587}
 588
 589impl MutableAppContext {
 590    fn new(
 591        foreground: Rc<executor::Foreground>,
 592        background: Arc<executor::Background>,
 593        platform: Arc<dyn platform::Platform>,
 594        foreground_platform: Rc<dyn platform::ForegroundPlatform>,
 595        asset_source: impl AssetSource,
 596    ) -> Self {
 597        let fonts = platform.fonts();
 598        Self {
 599            weak_self: None,
 600            foreground_platform,
 601            platform,
 602            assets: Arc::new(AssetCache::new(asset_source)),
 603            cx: AppContext {
 604                models: Default::default(),
 605                views: Default::default(),
 606                windows: Default::default(),
 607                values: Default::default(),
 608                ref_counts: Arc::new(Mutex::new(RefCounts::default())),
 609                background,
 610                font_cache: Arc::new(FontCache::new(fonts)),
 611            },
 612            actions: HashMap::new(),
 613            global_actions: HashMap::new(),
 614            keystroke_matcher: keymap::Matcher::default(),
 615            next_entity_id: 0,
 616            next_window_id: 0,
 617            subscriptions: HashMap::new(),
 618            model_observations: HashMap::new(),
 619            view_observations: HashMap::new(),
 620            presenters_and_platform_windows: HashMap::new(),
 621            debug_elements_callbacks: HashMap::new(),
 622            foreground,
 623            pending_effects: VecDeque::new(),
 624            pending_flushes: 0,
 625            flushing_effects: false,
 626        }
 627    }
 628
 629    pub fn upgrade(&self) -> App {
 630        App(self.weak_self.as_ref().unwrap().upgrade().unwrap())
 631    }
 632
 633    pub fn platform(&self) -> Arc<dyn platform::Platform> {
 634        self.platform.clone()
 635    }
 636
 637    pub fn font_cache(&self) -> &Arc<FontCache> {
 638        &self.cx.font_cache
 639    }
 640
 641    pub fn foreground(&self) -> &Rc<executor::Foreground> {
 642        &self.foreground
 643    }
 644
 645    pub fn background(&self) -> &Arc<executor::Background> {
 646        &self.cx.background
 647    }
 648
 649    pub fn on_debug_elements<F>(&mut self, window_id: usize, callback: F)
 650    where
 651        F: 'static + Fn(&AppContext) -> crate::json::Value,
 652    {
 653        self.debug_elements_callbacks
 654            .insert(window_id, Box::new(callback));
 655    }
 656
 657    pub fn debug_elements(&self, window_id: usize) -> Option<crate::json::Value> {
 658        self.debug_elements_callbacks
 659            .get(&window_id)
 660            .map(|debug_elements| debug_elements(&self.cx))
 661    }
 662
 663    pub fn add_action<S, V, T, F>(&mut self, name: S, mut handler: F)
 664    where
 665        S: Into<String>,
 666        V: View,
 667        T: Any,
 668        F: 'static + FnMut(&mut V, &T, &mut ViewContext<V>),
 669    {
 670        let name = name.into();
 671        let name_clone = name.clone();
 672        let handler = Box::new(
 673            move |view: &mut dyn AnyView,
 674                  arg: &dyn Any,
 675                  cx: &mut MutableAppContext,
 676                  window_id: usize,
 677                  view_id: usize| {
 678                match arg.downcast_ref() {
 679                    Some(arg) => {
 680                        let mut cx = ViewContext::new(cx, window_id, view_id);
 681                        handler(
 682                            view.as_any_mut()
 683                                .downcast_mut()
 684                                .expect("downcast is type safe"),
 685                            arg,
 686                            &mut cx,
 687                        );
 688                        cx.halt_action_dispatch
 689                    }
 690                    None => {
 691                        log::error!("Could not downcast argument for action {}", name_clone);
 692                        false
 693                    }
 694                }
 695            },
 696        );
 697
 698        self.actions
 699            .entry(TypeId::of::<V>())
 700            .or_default()
 701            .entry(name)
 702            .or_default()
 703            .push(handler);
 704    }
 705
 706    pub fn add_global_action<S, T, F>(&mut self, name: S, mut handler: F)
 707    where
 708        S: Into<String>,
 709        T: 'static + Any,
 710        F: 'static + FnMut(&T, &mut MutableAppContext),
 711    {
 712        let name = name.into();
 713        let name_clone = name.clone();
 714        let handler = Box::new(move |arg: &dyn Any, cx: &mut MutableAppContext| {
 715            if let Some(arg) = arg.downcast_ref() {
 716                handler(arg, cx);
 717            } else {
 718                log::error!("Could not downcast argument for action {}", name_clone);
 719            }
 720        });
 721
 722        self.global_actions.entry(name).or_default().push(handler);
 723    }
 724
 725    pub fn window_ids(&self) -> impl Iterator<Item = usize> + '_ {
 726        self.cx.windows.keys().cloned()
 727    }
 728
 729    pub fn root_view<T: View>(&self, window_id: usize) -> Option<ViewHandle<T>> {
 730        self.cx
 731            .windows
 732            .get(&window_id)
 733            .and_then(|window| window.root_view.clone().downcast::<T>())
 734    }
 735
 736    pub fn root_view_id(&self, window_id: usize) -> Option<usize> {
 737        self.cx.root_view_id(window_id)
 738    }
 739
 740    pub fn focused_view_id(&self, window_id: usize) -> Option<usize> {
 741        self.cx.focused_view_id(window_id)
 742    }
 743
 744    pub fn render_view(&self, window_id: usize, view_id: usize) -> Result<ElementBox> {
 745        self.cx.render_view(window_id, view_id)
 746    }
 747
 748    pub fn render_views(&self, window_id: usize) -> HashMap<usize, ElementBox> {
 749        self.cx.render_views(window_id)
 750    }
 751
 752    pub fn update<T, F: FnOnce() -> T>(&mut self, callback: F) -> T {
 753        self.pending_flushes += 1;
 754        let result = callback();
 755        self.flush_effects();
 756        result
 757    }
 758
 759    pub fn set_menus(&mut self, menus: Vec<Menu>) {
 760        self.foreground_platform.set_menus(menus);
 761    }
 762
 763    fn prompt<F>(
 764        &self,
 765        window_id: usize,
 766        level: PromptLevel,
 767        msg: &str,
 768        answers: &[&str],
 769        done_fn: F,
 770    ) where
 771        F: 'static + FnOnce(usize, &mut MutableAppContext),
 772    {
 773        let app = self.weak_self.as_ref().unwrap().upgrade().unwrap();
 774        let foreground = self.foreground.clone();
 775        let (_, window) = &self.presenters_and_platform_windows[&window_id];
 776        window.prompt(
 777            level,
 778            msg,
 779            answers,
 780            Box::new(move |answer| {
 781                foreground
 782                    .spawn(async move { (done_fn)(answer, &mut *app.borrow_mut()) })
 783                    .detach();
 784            }),
 785        );
 786    }
 787
 788    pub fn prompt_for_paths<F>(&self, options: PathPromptOptions, done_fn: F)
 789    where
 790        F: 'static + FnOnce(Option<Vec<PathBuf>>, &mut MutableAppContext),
 791    {
 792        let app = self.weak_self.as_ref().unwrap().upgrade().unwrap();
 793        let foreground = self.foreground.clone();
 794        self.foreground_platform.prompt_for_paths(
 795            options,
 796            Box::new(move |paths| {
 797                foreground
 798                    .spawn(async move { (done_fn)(paths, &mut *app.borrow_mut()) })
 799                    .detach();
 800            }),
 801        );
 802    }
 803
 804    pub fn prompt_for_new_path<F>(&self, directory: &Path, done_fn: F)
 805    where
 806        F: 'static + FnOnce(Option<PathBuf>, &mut MutableAppContext),
 807    {
 808        let app = self.weak_self.as_ref().unwrap().upgrade().unwrap();
 809        let foreground = self.foreground.clone();
 810        self.foreground_platform.prompt_for_new_path(
 811            directory,
 812            Box::new(move |path| {
 813                foreground
 814                    .spawn(async move { (done_fn)(path, &mut *app.borrow_mut()) })
 815                    .detach();
 816            }),
 817        );
 818    }
 819
 820    pub(crate) fn notify_view(&mut self, window_id: usize, view_id: usize) {
 821        self.pending_effects
 822            .push_back(Effect::ViewNotification { window_id, view_id });
 823    }
 824
 825    pub fn dispatch_action<T: 'static + Any>(
 826        &mut self,
 827        window_id: usize,
 828        responder_chain: Vec<usize>,
 829        name: &str,
 830        arg: T,
 831    ) {
 832        self.dispatch_action_any(window_id, &responder_chain, name, Box::new(arg).as_ref());
 833    }
 834
 835    pub(crate) fn dispatch_action_any(
 836        &mut self,
 837        window_id: usize,
 838        path: &[usize],
 839        name: &str,
 840        arg: &dyn Any,
 841    ) -> bool {
 842        self.pending_flushes += 1;
 843        let mut halted_dispatch = false;
 844
 845        for view_id in path.iter().rev() {
 846            if let Some(mut view) = self.cx.views.remove(&(window_id, *view_id)) {
 847                let type_id = view.as_any().type_id();
 848
 849                if let Some((name, mut handlers)) = self
 850                    .actions
 851                    .get_mut(&type_id)
 852                    .and_then(|h| h.remove_entry(name))
 853                {
 854                    for handler in handlers.iter_mut().rev() {
 855                        let halt_dispatch = handler(view.as_mut(), arg, self, window_id, *view_id);
 856                        if halt_dispatch {
 857                            halted_dispatch = true;
 858                            break;
 859                        }
 860                    }
 861                    self.actions
 862                        .get_mut(&type_id)
 863                        .unwrap()
 864                        .insert(name, handlers);
 865                }
 866
 867                self.cx.views.insert((window_id, *view_id), view);
 868
 869                if halted_dispatch {
 870                    break;
 871                }
 872            }
 873        }
 874
 875        if !halted_dispatch {
 876            self.dispatch_global_action_any(name, arg);
 877        }
 878
 879        self.flush_effects();
 880        halted_dispatch
 881    }
 882
 883    pub fn dispatch_global_action<T: 'static + Any>(&mut self, name: &str, arg: T) {
 884        self.dispatch_global_action_any(name, Box::new(arg).as_ref());
 885    }
 886
 887    fn dispatch_global_action_any(&mut self, name: &str, arg: &dyn Any) {
 888        if let Some((name, mut handlers)) = self.global_actions.remove_entry(name) {
 889            self.pending_flushes += 1;
 890            for handler in handlers.iter_mut().rev() {
 891                handler(arg, self);
 892            }
 893            self.global_actions.insert(name, handlers);
 894            self.flush_effects();
 895        }
 896    }
 897
 898    pub fn add_bindings<T: IntoIterator<Item = keymap::Binding>>(&mut self, bindings: T) {
 899        self.keystroke_matcher.add_bindings(bindings);
 900    }
 901
 902    pub fn dispatch_keystroke(
 903        &mut self,
 904        window_id: usize,
 905        responder_chain: Vec<usize>,
 906        keystroke: &Keystroke,
 907    ) -> Result<bool> {
 908        let mut context_chain = Vec::new();
 909        let mut context = keymap::Context::default();
 910        for view_id in &responder_chain {
 911            if let Some(view) = self.cx.views.get(&(window_id, *view_id)) {
 912                context.extend(view.keymap_context(self.as_ref()));
 913                context_chain.push(context.clone());
 914            } else {
 915                return Err(anyhow!(
 916                    "View {} in responder chain does not exist",
 917                    view_id
 918                ));
 919            }
 920        }
 921
 922        let mut pending = false;
 923        for (i, cx) in context_chain.iter().enumerate().rev() {
 924            match self
 925                .keystroke_matcher
 926                .push_keystroke(keystroke.clone(), responder_chain[i], cx)
 927            {
 928                MatchResult::None => {}
 929                MatchResult::Pending => pending = true,
 930                MatchResult::Action { name, arg } => {
 931                    if self.dispatch_action_any(
 932                        window_id,
 933                        &responder_chain[0..=i],
 934                        &name,
 935                        arg.as_ref().map(|arg| arg.as_ref()).unwrap_or(&()),
 936                    ) {
 937                        return Ok(true);
 938                    }
 939                }
 940            }
 941        }
 942
 943        Ok(pending)
 944    }
 945
 946    pub fn add_model<T, F>(&mut self, build_model: F) -> ModelHandle<T>
 947    where
 948        T: Entity,
 949        F: FnOnce(&mut ModelContext<T>) -> T,
 950    {
 951        self.pending_flushes += 1;
 952        let model_id = post_inc(&mut self.next_entity_id);
 953        let handle = ModelHandle::new(model_id, &self.cx.ref_counts);
 954        let mut cx = ModelContext::new(self, model_id);
 955        let model = build_model(&mut cx);
 956        self.cx.models.insert(model_id, Box::new(model));
 957        self.flush_effects();
 958        handle
 959    }
 960
 961    pub fn add_window<T, F>(&mut self, build_root_view: F) -> (usize, ViewHandle<T>)
 962    where
 963        T: View,
 964        F: FnOnce(&mut ViewContext<T>) -> T,
 965    {
 966        self.pending_flushes += 1;
 967        let window_id = post_inc(&mut self.next_window_id);
 968        let root_view = self.add_view(window_id, build_root_view);
 969
 970        self.cx.windows.insert(
 971            window_id,
 972            Window {
 973                root_view: root_view.clone().into(),
 974                focused_view_id: root_view.id(),
 975                invalidation: None,
 976            },
 977        );
 978        self.open_platform_window(window_id);
 979        root_view.update(self, |view, cx| {
 980            view.on_focus(cx);
 981            cx.notify();
 982        });
 983        self.flush_effects();
 984
 985        (window_id, root_view)
 986    }
 987
 988    pub fn remove_window(&mut self, window_id: usize) {
 989        self.cx.windows.remove(&window_id);
 990        self.presenters_and_platform_windows.remove(&window_id);
 991        self.remove_dropped_entities();
 992    }
 993
 994    fn open_platform_window(&mut self, window_id: usize) {
 995        let mut window = self.platform.open_window(
 996            window_id,
 997            WindowOptions {
 998                bounds: RectF::new(vec2f(0., 0.), vec2f(1024., 768.)),
 999                title: "Zed".into(),
1000            },
1001            self.foreground.clone(),
1002        );
1003        let text_layout_cache = TextLayoutCache::new(self.platform.fonts());
1004        let presenter = Rc::new(RefCell::new(Presenter::new(
1005            window_id,
1006            self.cx.font_cache.clone(),
1007            text_layout_cache,
1008            self.assets.clone(),
1009            self,
1010        )));
1011
1012        {
1013            let mut app = self.upgrade();
1014            let presenter = presenter.clone();
1015            window.on_event(Box::new(move |event| {
1016                app.update(|cx| {
1017                    if let Event::KeyDown { keystroke, .. } = &event {
1018                        if cx
1019                            .dispatch_keystroke(
1020                                window_id,
1021                                presenter.borrow().dispatch_path(cx.as_ref()),
1022                                keystroke,
1023                            )
1024                            .unwrap()
1025                        {
1026                            return;
1027                        }
1028                    }
1029
1030                    presenter.borrow_mut().dispatch_event(event, cx);
1031                })
1032            }));
1033        }
1034
1035        {
1036            let mut app = self.upgrade();
1037            let presenter = presenter.clone();
1038            window.on_resize(Box::new(move |window| {
1039                app.update(|cx| {
1040                    let scene = presenter.borrow_mut().build_scene(
1041                        window.size(),
1042                        window.scale_factor(),
1043                        cx,
1044                    );
1045                    window.present_scene(scene);
1046                })
1047            }));
1048        }
1049
1050        {
1051            let mut app = self.upgrade();
1052            window.on_close(Box::new(move || {
1053                app.update(|cx| cx.remove_window(window_id));
1054            }));
1055        }
1056
1057        self.presenters_and_platform_windows
1058            .insert(window_id, (presenter.clone(), window));
1059
1060        self.on_debug_elements(window_id, move |cx| {
1061            presenter.borrow().debug_elements(cx).unwrap()
1062        });
1063    }
1064
1065    pub fn add_view<T, F>(&mut self, window_id: usize, build_view: F) -> ViewHandle<T>
1066    where
1067        T: View,
1068        F: FnOnce(&mut ViewContext<T>) -> T,
1069    {
1070        self.add_option_view(window_id, |cx| Some(build_view(cx)))
1071            .unwrap()
1072    }
1073
1074    pub fn add_option_view<T, F>(
1075        &mut self,
1076        window_id: usize,
1077        build_view: F,
1078    ) -> Option<ViewHandle<T>>
1079    where
1080        T: View,
1081        F: FnOnce(&mut ViewContext<T>) -> Option<T>,
1082    {
1083        let view_id = post_inc(&mut self.next_entity_id);
1084        self.pending_flushes += 1;
1085        let handle = ViewHandle::new(window_id, view_id, &self.cx.ref_counts);
1086        let mut cx = ViewContext::new(self, window_id, view_id);
1087        let handle = if let Some(view) = build_view(&mut cx) {
1088            self.cx.views.insert((window_id, view_id), Box::new(view));
1089            if let Some(window) = self.cx.windows.get_mut(&window_id) {
1090                window
1091                    .invalidation
1092                    .get_or_insert_with(Default::default)
1093                    .updated
1094                    .insert(view_id);
1095            }
1096            Some(handle)
1097        } else {
1098            None
1099        };
1100        self.flush_effects();
1101        handle
1102    }
1103
1104    fn remove_dropped_entities(&mut self) {
1105        loop {
1106            let (dropped_models, dropped_views, dropped_values) =
1107                self.cx.ref_counts.lock().take_dropped();
1108            if dropped_models.is_empty() && dropped_views.is_empty() && dropped_values.is_empty() {
1109                break;
1110            }
1111
1112            for model_id in dropped_models {
1113                self.subscriptions.remove(&model_id);
1114                self.model_observations.remove(&model_id);
1115                let mut model = self.cx.models.remove(&model_id).unwrap();
1116                model.release(self);
1117            }
1118
1119            for (window_id, view_id) in dropped_views {
1120                self.subscriptions.remove(&view_id);
1121                self.model_observations.remove(&view_id);
1122                let mut view = self.cx.views.remove(&(window_id, view_id)).unwrap();
1123                view.release(self);
1124                let change_focus_to = self.cx.windows.get_mut(&window_id).and_then(|window| {
1125                    window
1126                        .invalidation
1127                        .get_or_insert_with(Default::default)
1128                        .removed
1129                        .push(view_id);
1130                    if window.focused_view_id == view_id {
1131                        Some(window.root_view.id())
1132                    } else {
1133                        None
1134                    }
1135                });
1136
1137                if let Some(view_id) = change_focus_to {
1138                    self.focus(window_id, view_id);
1139                }
1140            }
1141
1142            let mut values = self.cx.values.write();
1143            for key in dropped_values {
1144                values.remove(&key);
1145            }
1146        }
1147    }
1148
1149    fn flush_effects(&mut self) {
1150        self.pending_flushes = self.pending_flushes.saturating_sub(1);
1151
1152        if !self.flushing_effects && self.pending_flushes == 0 {
1153            self.flushing_effects = true;
1154
1155            loop {
1156                if let Some(effect) = self.pending_effects.pop_front() {
1157                    match effect {
1158                        Effect::Event { entity_id, payload } => self.emit_event(entity_id, payload),
1159                        Effect::ModelNotification { model_id } => {
1160                            self.notify_model_observers(model_id)
1161                        }
1162                        Effect::ViewNotification { window_id, view_id } => {
1163                            self.notify_view_observers(window_id, view_id)
1164                        }
1165                        Effect::Focus { window_id, view_id } => {
1166                            self.focus(window_id, view_id);
1167                        }
1168                    }
1169                    self.remove_dropped_entities();
1170                } else {
1171                    self.remove_dropped_entities();
1172                    self.update_windows();
1173
1174                    if self.pending_effects.is_empty() {
1175                        self.flushing_effects = false;
1176                        break;
1177                    }
1178                }
1179            }
1180        }
1181    }
1182
1183    fn update_windows(&mut self) {
1184        let mut invalidations = HashMap::new();
1185        for (window_id, window) in &mut self.cx.windows {
1186            if let Some(invalidation) = window.invalidation.take() {
1187                invalidations.insert(*window_id, invalidation);
1188            }
1189        }
1190
1191        for (window_id, invalidation) in invalidations {
1192            if let Some((presenter, mut window)) =
1193                self.presenters_and_platform_windows.remove(&window_id)
1194            {
1195                {
1196                    let mut presenter = presenter.borrow_mut();
1197                    presenter.invalidate(invalidation, self.as_ref());
1198                    let scene = presenter.build_scene(window.size(), window.scale_factor(), self);
1199                    window.present_scene(scene);
1200                }
1201                self.presenters_and_platform_windows
1202                    .insert(window_id, (presenter, window));
1203            }
1204        }
1205    }
1206
1207    fn emit_event(&mut self, entity_id: usize, payload: Box<dyn Any>) {
1208        if let Some(subscriptions) = self.subscriptions.remove(&entity_id) {
1209            for mut subscription in subscriptions {
1210                let alive = match &mut subscription {
1211                    Subscription::FromModel { model_id, callback } => {
1212                        if let Some(mut model) = self.cx.models.remove(model_id) {
1213                            callback(model.as_any_mut(), payload.as_ref(), self, *model_id);
1214                            self.cx.models.insert(*model_id, model);
1215                            true
1216                        } else {
1217                            false
1218                        }
1219                    }
1220                    Subscription::FromView {
1221                        window_id,
1222                        view_id,
1223                        callback,
1224                    } => {
1225                        if let Some(mut view) = self.cx.views.remove(&(*window_id, *view_id)) {
1226                            callback(
1227                                view.as_any_mut(),
1228                                payload.as_ref(),
1229                                self,
1230                                *window_id,
1231                                *view_id,
1232                            );
1233                            self.cx.views.insert((*window_id, *view_id), view);
1234                            true
1235                        } else {
1236                            false
1237                        }
1238                    }
1239                };
1240
1241                if alive {
1242                    self.subscriptions
1243                        .entry(entity_id)
1244                        .or_default()
1245                        .push(subscription);
1246                }
1247            }
1248        }
1249    }
1250
1251    fn notify_model_observers(&mut self, observed_id: usize) {
1252        if let Some(observations) = self.model_observations.remove(&observed_id) {
1253            if self.cx.models.contains_key(&observed_id) {
1254                for mut observation in observations {
1255                    let alive = match &mut observation {
1256                        ModelObservation::FromModel { model_id, callback } => {
1257                            if let Some(mut model) = self.cx.models.remove(model_id) {
1258                                callback(model.as_any_mut(), observed_id, self, *model_id);
1259                                self.cx.models.insert(*model_id, model);
1260                                true
1261                            } else {
1262                                false
1263                            }
1264                        }
1265                        ModelObservation::FromView {
1266                            window_id,
1267                            view_id,
1268                            callback,
1269                        } => {
1270                            if let Some(mut view) = self.cx.views.remove(&(*window_id, *view_id)) {
1271                                callback(
1272                                    view.as_any_mut(),
1273                                    observed_id,
1274                                    self,
1275                                    *window_id,
1276                                    *view_id,
1277                                );
1278                                self.cx.views.insert((*window_id, *view_id), view);
1279                                true
1280                            } else {
1281                                false
1282                            }
1283                        }
1284                    };
1285
1286                    if alive {
1287                        self.model_observations
1288                            .entry(observed_id)
1289                            .or_default()
1290                            .push(observation);
1291                    }
1292                }
1293            }
1294        }
1295    }
1296
1297    fn notify_view_observers(&mut self, window_id: usize, view_id: usize) {
1298        if let Some(window) = self.cx.windows.get_mut(&window_id) {
1299            window
1300                .invalidation
1301                .get_or_insert_with(Default::default)
1302                .updated
1303                .insert(view_id);
1304        }
1305
1306        if let Some(observations) = self.view_observations.remove(&view_id) {
1307            if self.cx.views.contains_key(&(window_id, view_id)) {
1308                for mut observation in observations {
1309                    let alive = if let Some(mut view) = self
1310                        .cx
1311                        .views
1312                        .remove(&(observation.window_id, observation.view_id))
1313                    {
1314                        (observation.callback)(
1315                            view.as_any_mut(),
1316                            view_id,
1317                            window_id,
1318                            self,
1319                            observation.window_id,
1320                            observation.view_id,
1321                        );
1322                        self.cx
1323                            .views
1324                            .insert((observation.window_id, observation.view_id), view);
1325                        true
1326                    } else {
1327                        false
1328                    };
1329
1330                    if alive {
1331                        self.view_observations
1332                            .entry(view_id)
1333                            .or_default()
1334                            .push(observation);
1335                    }
1336                }
1337            }
1338        }
1339    }
1340
1341    fn focus(&mut self, window_id: usize, focused_id: usize) {
1342        if self
1343            .cx
1344            .windows
1345            .get(&window_id)
1346            .map(|w| w.focused_view_id)
1347            .map_or(false, |cur_focused| cur_focused == focused_id)
1348        {
1349            return;
1350        }
1351
1352        self.pending_flushes += 1;
1353
1354        let blurred_id = self.cx.windows.get_mut(&window_id).map(|window| {
1355            let blurred_id = window.focused_view_id;
1356            window.focused_view_id = focused_id;
1357            blurred_id
1358        });
1359
1360        if let Some(blurred_id) = blurred_id {
1361            if let Some(mut blurred_view) = self.cx.views.remove(&(window_id, blurred_id)) {
1362                blurred_view.on_blur(self, window_id, blurred_id);
1363                self.cx.views.insert((window_id, blurred_id), blurred_view);
1364            }
1365        }
1366
1367        if let Some(mut focused_view) = self.cx.views.remove(&(window_id, focused_id)) {
1368            focused_view.on_focus(self, window_id, focused_id);
1369            self.cx.views.insert((window_id, focused_id), focused_view);
1370        }
1371
1372        self.flush_effects();
1373    }
1374
1375    pub fn spawn<F, Fut, T>(&self, f: F) -> Task<T>
1376    where
1377        F: FnOnce(AsyncAppContext) -> Fut,
1378        Fut: 'static + Future<Output = T>,
1379        T: 'static,
1380    {
1381        let cx = self.to_async();
1382        self.foreground.spawn(f(cx))
1383    }
1384
1385    pub fn to_async(&self) -> AsyncAppContext {
1386        AsyncAppContext(self.weak_self.as_ref().unwrap().upgrade().unwrap())
1387    }
1388
1389    pub fn write_to_clipboard(&self, item: ClipboardItem) {
1390        self.platform.write_to_clipboard(item);
1391    }
1392
1393    pub fn read_from_clipboard(&self) -> Option<ClipboardItem> {
1394        self.platform.read_from_clipboard()
1395    }
1396}
1397
1398impl ReadModel for MutableAppContext {
1399    fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T {
1400        if let Some(model) = self.cx.models.get(&handle.model_id) {
1401            model
1402                .as_any()
1403                .downcast_ref()
1404                .expect("downcast is type safe")
1405        } else {
1406            panic!("circular model reference");
1407        }
1408    }
1409}
1410
1411impl UpdateModel for MutableAppContext {
1412    fn update_model<T, F, S>(&mut self, handle: &ModelHandle<T>, update: F) -> S
1413    where
1414        T: Entity,
1415        F: FnOnce(&mut T, &mut ModelContext<T>) -> S,
1416    {
1417        if let Some(mut model) = self.cx.models.remove(&handle.model_id) {
1418            self.pending_flushes += 1;
1419            let mut cx = ModelContext::new(self, handle.model_id);
1420            let result = update(
1421                model
1422                    .as_any_mut()
1423                    .downcast_mut()
1424                    .expect("downcast is type safe"),
1425                &mut cx,
1426            );
1427            self.cx.models.insert(handle.model_id, model);
1428            self.flush_effects();
1429            result
1430        } else {
1431            panic!("circular model update");
1432        }
1433    }
1434}
1435
1436impl ReadView for MutableAppContext {
1437    fn read_view<T: View>(&self, handle: &ViewHandle<T>) -> &T {
1438        if let Some(view) = self.cx.views.get(&(handle.window_id, handle.view_id)) {
1439            view.as_any().downcast_ref().expect("downcast is type safe")
1440        } else {
1441            panic!("circular view reference");
1442        }
1443    }
1444}
1445
1446impl UpdateView for MutableAppContext {
1447    fn update_view<T, F, S>(&mut self, handle: &ViewHandle<T>, update: F) -> S
1448    where
1449        T: View,
1450        F: FnOnce(&mut T, &mut ViewContext<T>) -> S,
1451    {
1452        self.pending_flushes += 1;
1453        let mut view = self
1454            .cx
1455            .views
1456            .remove(&(handle.window_id, handle.view_id))
1457            .expect("circular view update");
1458
1459        let mut cx = ViewContext::new(self, handle.window_id, handle.view_id);
1460        let result = update(
1461            view.as_any_mut()
1462                .downcast_mut()
1463                .expect("downcast is type safe"),
1464            &mut cx,
1465        );
1466        self.cx
1467            .views
1468            .insert((handle.window_id, handle.view_id), view);
1469        self.flush_effects();
1470        result
1471    }
1472}
1473
1474impl AsRef<AppContext> for MutableAppContext {
1475    fn as_ref(&self) -> &AppContext {
1476        &self.cx
1477    }
1478}
1479
1480pub struct AppContext {
1481    models: HashMap<usize, Box<dyn AnyModel>>,
1482    views: HashMap<(usize, usize), Box<dyn AnyView>>,
1483    windows: HashMap<usize, Window>,
1484    values: RwLock<HashMap<(TypeId, usize), Box<dyn Any>>>,
1485    background: Arc<executor::Background>,
1486    ref_counts: Arc<Mutex<RefCounts>>,
1487    font_cache: Arc<FontCache>,
1488}
1489
1490impl AppContext {
1491    pub fn root_view_id(&self, window_id: usize) -> Option<usize> {
1492        self.windows
1493            .get(&window_id)
1494            .map(|window| window.root_view.id())
1495    }
1496
1497    pub fn focused_view_id(&self, window_id: usize) -> Option<usize> {
1498        self.windows
1499            .get(&window_id)
1500            .map(|window| window.focused_view_id)
1501    }
1502
1503    pub fn render_view(&self, window_id: usize, view_id: usize) -> Result<ElementBox> {
1504        self.views
1505            .get(&(window_id, view_id))
1506            .map(|v| v.render(self))
1507            .ok_or(anyhow!("view not found"))
1508    }
1509
1510    pub fn render_views(&self, window_id: usize) -> HashMap<usize, ElementBox> {
1511        self.views
1512            .iter()
1513            .filter_map(|((win_id, view_id), view)| {
1514                if *win_id == window_id {
1515                    Some((*view_id, view.render(self)))
1516                } else {
1517                    None
1518                }
1519            })
1520            .collect::<HashMap<_, ElementBox>>()
1521    }
1522
1523    pub fn background(&self) -> &Arc<executor::Background> {
1524        &self.background
1525    }
1526
1527    pub fn font_cache(&self) -> &FontCache {
1528        &self.font_cache
1529    }
1530
1531    pub fn value<Tag: 'static, T: 'static + Default>(&self, id: usize) -> ValueHandle<T> {
1532        let key = (TypeId::of::<Tag>(), id);
1533        let mut values = self.values.write();
1534        values.entry(key).or_insert_with(|| Box::new(T::default()));
1535        ValueHandle::new(TypeId::of::<Tag>(), id, &self.ref_counts)
1536    }
1537}
1538
1539impl ReadModel for AppContext {
1540    fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T {
1541        if let Some(model) = self.models.get(&handle.model_id) {
1542            model
1543                .as_any()
1544                .downcast_ref()
1545                .expect("downcast should be type safe")
1546        } else {
1547            panic!("circular model reference");
1548        }
1549    }
1550}
1551
1552impl ReadView for AppContext {
1553    fn read_view<T: View>(&self, handle: &ViewHandle<T>) -> &T {
1554        if let Some(view) = self.views.get(&(handle.window_id, handle.view_id)) {
1555            view.as_any()
1556                .downcast_ref()
1557                .expect("downcast should be type safe")
1558        } else {
1559            panic!("circular view reference");
1560        }
1561    }
1562}
1563
1564struct Window {
1565    root_view: AnyViewHandle,
1566    focused_view_id: usize,
1567    invalidation: Option<WindowInvalidation>,
1568}
1569
1570#[derive(Default, Clone)]
1571pub struct WindowInvalidation {
1572    pub updated: HashSet<usize>,
1573    pub removed: Vec<usize>,
1574}
1575
1576pub enum Effect {
1577    Event {
1578        entity_id: usize,
1579        payload: Box<dyn Any>,
1580    },
1581    ModelNotification {
1582        model_id: usize,
1583    },
1584    ViewNotification {
1585        window_id: usize,
1586        view_id: usize,
1587    },
1588    Focus {
1589        window_id: usize,
1590        view_id: usize,
1591    },
1592}
1593
1594impl Debug for Effect {
1595    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1596        match self {
1597            Effect::Event { entity_id, .. } => f
1598                .debug_struct("Effect::Event")
1599                .field("entity_id", entity_id)
1600                .finish(),
1601            Effect::ModelNotification { model_id } => f
1602                .debug_struct("Effect::ModelNotification")
1603                .field("model_id", model_id)
1604                .finish(),
1605            Effect::ViewNotification { window_id, view_id } => f
1606                .debug_struct("Effect::ViewNotification")
1607                .field("window_id", window_id)
1608                .field("view_id", view_id)
1609                .finish(),
1610            Effect::Focus { window_id, view_id } => f
1611                .debug_struct("Effect::Focus")
1612                .field("window_id", window_id)
1613                .field("view_id", view_id)
1614                .finish(),
1615        }
1616    }
1617}
1618
1619pub trait AnyModel: Send + Sync {
1620    fn as_any(&self) -> &dyn Any;
1621    fn as_any_mut(&mut self) -> &mut dyn Any;
1622    fn release(&mut self, cx: &mut MutableAppContext);
1623}
1624
1625impl<T> AnyModel for T
1626where
1627    T: Entity,
1628{
1629    fn as_any(&self) -> &dyn Any {
1630        self
1631    }
1632
1633    fn as_any_mut(&mut self) -> &mut dyn Any {
1634        self
1635    }
1636
1637    fn release(&mut self, cx: &mut MutableAppContext) {
1638        self.release(cx);
1639    }
1640}
1641
1642pub trait AnyView: Send + Sync {
1643    fn as_any(&self) -> &dyn Any;
1644    fn as_any_mut(&mut self) -> &mut dyn Any;
1645    fn release(&mut self, cx: &mut MutableAppContext);
1646    fn ui_name(&self) -> &'static str;
1647    fn render<'a>(&self, cx: &AppContext) -> ElementBox;
1648    fn on_focus(&mut self, cx: &mut MutableAppContext, window_id: usize, view_id: usize);
1649    fn on_blur(&mut self, cx: &mut MutableAppContext, window_id: usize, view_id: usize);
1650    fn keymap_context(&self, cx: &AppContext) -> keymap::Context;
1651}
1652
1653impl<T> AnyView for T
1654where
1655    T: View,
1656{
1657    fn as_any(&self) -> &dyn Any {
1658        self
1659    }
1660
1661    fn as_any_mut(&mut self) -> &mut dyn Any {
1662        self
1663    }
1664
1665    fn release(&mut self, cx: &mut MutableAppContext) {
1666        self.release(cx);
1667    }
1668
1669    fn ui_name(&self) -> &'static str {
1670        T::ui_name()
1671    }
1672
1673    fn render<'a>(&self, cx: &AppContext) -> ElementBox {
1674        View::render(self, cx)
1675    }
1676
1677    fn on_focus(&mut self, cx: &mut MutableAppContext, window_id: usize, view_id: usize) {
1678        let mut cx = ViewContext::new(cx, window_id, view_id);
1679        View::on_focus(self, &mut cx);
1680    }
1681
1682    fn on_blur(&mut self, cx: &mut MutableAppContext, window_id: usize, view_id: usize) {
1683        let mut cx = ViewContext::new(cx, window_id, view_id);
1684        View::on_blur(self, &mut cx);
1685    }
1686
1687    fn keymap_context(&self, cx: &AppContext) -> keymap::Context {
1688        View::keymap_context(self, cx)
1689    }
1690}
1691
1692pub struct ModelContext<'a, T: ?Sized> {
1693    app: &'a mut MutableAppContext,
1694    model_id: usize,
1695    model_type: PhantomData<T>,
1696    halt_stream: bool,
1697}
1698
1699impl<'a, T: Entity> ModelContext<'a, T> {
1700    fn new(app: &'a mut MutableAppContext, model_id: usize) -> Self {
1701        Self {
1702            app,
1703            model_id,
1704            model_type: PhantomData,
1705            halt_stream: false,
1706        }
1707    }
1708
1709    pub fn background(&self) -> &Arc<executor::Background> {
1710        &self.app.cx.background
1711    }
1712
1713    pub fn halt_stream(&mut self) {
1714        self.halt_stream = true;
1715    }
1716
1717    pub fn model_id(&self) -> usize {
1718        self.model_id
1719    }
1720
1721    pub fn add_model<S, F>(&mut self, build_model: F) -> ModelHandle<S>
1722    where
1723        S: Entity,
1724        F: FnOnce(&mut ModelContext<S>) -> S,
1725    {
1726        self.app.add_model(build_model)
1727    }
1728
1729    pub fn subscribe<S: Entity, F>(&mut self, handle: &ModelHandle<S>, mut callback: F)
1730    where
1731        S::Event: 'static,
1732        F: 'static + FnMut(&mut T, &S::Event, &mut ModelContext<T>),
1733    {
1734        self.app
1735            .subscriptions
1736            .entry(handle.model_id)
1737            .or_default()
1738            .push(Subscription::FromModel {
1739                model_id: self.model_id,
1740                callback: Box::new(move |model, payload, app, model_id| {
1741                    let model = model.downcast_mut().expect("downcast is type safe");
1742                    let payload = payload.downcast_ref().expect("downcast is type safe");
1743                    let mut cx = ModelContext::new(app, model_id);
1744                    callback(model, payload, &mut cx);
1745                }),
1746            });
1747    }
1748
1749    pub fn emit(&mut self, payload: T::Event) {
1750        self.app.pending_effects.push_back(Effect::Event {
1751            entity_id: self.model_id,
1752            payload: Box::new(payload),
1753        });
1754    }
1755
1756    pub fn observe<S, F>(&mut self, handle: &ModelHandle<S>, mut callback: F)
1757    where
1758        S: Entity,
1759        F: 'static + FnMut(&mut T, ModelHandle<S>, &mut ModelContext<T>),
1760    {
1761        self.app
1762            .model_observations
1763            .entry(handle.model_id)
1764            .or_default()
1765            .push(ModelObservation::FromModel {
1766                model_id: self.model_id,
1767                callback: Box::new(move |model, observed_id, app, model_id| {
1768                    let model = model.downcast_mut().expect("downcast is type safe");
1769                    let observed = ModelHandle::new(observed_id, &app.cx.ref_counts);
1770                    let mut cx = ModelContext::new(app, model_id);
1771                    callback(model, observed, &mut cx);
1772                }),
1773            });
1774    }
1775
1776    pub fn notify(&mut self) {
1777        self.app
1778            .pending_effects
1779            .push_back(Effect::ModelNotification {
1780                model_id: self.model_id,
1781            });
1782    }
1783
1784    pub fn handle(&self) -> ModelHandle<T> {
1785        ModelHandle::new(self.model_id, &self.app.cx.ref_counts)
1786    }
1787
1788    pub fn spawn<F, Fut, S>(&self, f: F) -> Task<S>
1789    where
1790        F: FnOnce(ModelHandle<T>, AsyncAppContext) -> Fut,
1791        Fut: 'static + Future<Output = S>,
1792        S: 'static,
1793    {
1794        let handle = self.handle();
1795        self.app.spawn(|cx| f(handle, cx))
1796    }
1797
1798    pub fn spawn_weak<F, Fut, S>(&self, f: F) -> Task<S>
1799    where
1800        F: FnOnce(WeakModelHandle<T>, AsyncAppContext) -> Fut,
1801        Fut: 'static + Future<Output = S>,
1802        S: 'static,
1803    {
1804        let handle = self.handle().downgrade();
1805        self.app.spawn(|cx| f(handle, cx))
1806    }
1807}
1808
1809impl<M> AsRef<AppContext> for ModelContext<'_, M> {
1810    fn as_ref(&self) -> &AppContext {
1811        &self.app.cx
1812    }
1813}
1814
1815impl<M> AsMut<MutableAppContext> for ModelContext<'_, M> {
1816    fn as_mut(&mut self) -> &mut MutableAppContext {
1817        self.app
1818    }
1819}
1820
1821impl<M> ReadModel for ModelContext<'_, M> {
1822    fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T {
1823        self.app.read_model(handle)
1824    }
1825}
1826
1827impl<M> UpdateModel for ModelContext<'_, M> {
1828    fn update_model<T, F, S>(&mut self, handle: &ModelHandle<T>, update: F) -> S
1829    where
1830        T: Entity,
1831        F: FnOnce(&mut T, &mut ModelContext<T>) -> S,
1832    {
1833        self.app.update_model(handle, update)
1834    }
1835}
1836
1837pub struct ViewContext<'a, T: ?Sized> {
1838    app: &'a mut MutableAppContext,
1839    window_id: usize,
1840    view_id: usize,
1841    view_type: PhantomData<T>,
1842    halt_action_dispatch: bool,
1843}
1844
1845impl<'a, T: View> ViewContext<'a, T> {
1846    fn new(app: &'a mut MutableAppContext, window_id: usize, view_id: usize) -> Self {
1847        Self {
1848            app,
1849            window_id,
1850            view_id,
1851            view_type: PhantomData,
1852            halt_action_dispatch: true,
1853        }
1854    }
1855
1856    pub fn handle(&self) -> ViewHandle<T> {
1857        ViewHandle::new(self.window_id, self.view_id, &self.app.cx.ref_counts)
1858    }
1859
1860    pub fn window_id(&self) -> usize {
1861        self.window_id
1862    }
1863
1864    pub fn view_id(&self) -> usize {
1865        self.view_id
1866    }
1867
1868    pub fn foreground(&self) -> &Rc<executor::Foreground> {
1869        self.app.foreground()
1870    }
1871
1872    pub fn background_executor(&self) -> &Arc<executor::Background> {
1873        &self.app.cx.background
1874    }
1875
1876    pub fn platform(&self) -> Arc<dyn Platform> {
1877        self.app.platform()
1878    }
1879
1880    pub fn prompt<F>(&self, level: PromptLevel, msg: &str, answers: &[&str], done_fn: F)
1881    where
1882        F: 'static + FnOnce(usize, &mut MutableAppContext),
1883    {
1884        self.app
1885            .prompt(self.window_id, level, msg, answers, done_fn)
1886    }
1887
1888    pub fn prompt_for_paths<F>(&self, options: PathPromptOptions, done_fn: F)
1889    where
1890        F: 'static + FnOnce(Option<Vec<PathBuf>>, &mut MutableAppContext),
1891    {
1892        self.app.prompt_for_paths(options, done_fn)
1893    }
1894
1895    pub fn prompt_for_new_path<F>(&self, directory: &Path, done_fn: F)
1896    where
1897        F: 'static + FnOnce(Option<PathBuf>, &mut MutableAppContext),
1898    {
1899        self.app.prompt_for_new_path(directory, done_fn)
1900    }
1901
1902    pub fn debug_elements(&self) -> crate::json::Value {
1903        self.app.debug_elements(self.window_id).unwrap()
1904    }
1905
1906    pub fn focus<S>(&mut self, handle: S)
1907    where
1908        S: Into<AnyViewHandle>,
1909    {
1910        let handle = handle.into();
1911        self.app.pending_effects.push_back(Effect::Focus {
1912            window_id: handle.window_id,
1913            view_id: handle.view_id,
1914        });
1915    }
1916
1917    pub fn focus_self(&mut self) {
1918        self.app.pending_effects.push_back(Effect::Focus {
1919            window_id: self.window_id,
1920            view_id: self.view_id,
1921        });
1922    }
1923
1924    pub fn add_model<S, F>(&mut self, build_model: F) -> ModelHandle<S>
1925    where
1926        S: Entity,
1927        F: FnOnce(&mut ModelContext<S>) -> S,
1928    {
1929        self.app.add_model(build_model)
1930    }
1931
1932    pub fn add_view<S, F>(&mut self, build_view: F) -> ViewHandle<S>
1933    where
1934        S: View,
1935        F: FnOnce(&mut ViewContext<S>) -> S,
1936    {
1937        self.app.add_view(self.window_id, build_view)
1938    }
1939
1940    pub fn add_option_view<S, F>(&mut self, build_view: F) -> Option<ViewHandle<S>>
1941    where
1942        S: View,
1943        F: FnOnce(&mut ViewContext<S>) -> Option<S>,
1944    {
1945        self.app.add_option_view(self.window_id, build_view)
1946    }
1947
1948    pub fn subscribe_to_model<E, F>(&mut self, handle: &ModelHandle<E>, mut callback: F)
1949    where
1950        E: Entity,
1951        E::Event: 'static,
1952        F: 'static + FnMut(&mut T, ModelHandle<E>, &E::Event, &mut ViewContext<T>),
1953    {
1954        let emitter_handle = handle.downgrade();
1955        self.subscribe(handle, move |model, payload, cx| {
1956            if let Some(emitter_handle) = emitter_handle.upgrade(cx.as_ref()) {
1957                callback(model, emitter_handle, payload, cx);
1958            }
1959        });
1960    }
1961
1962    pub fn subscribe_to_view<V, F>(&mut self, handle: &ViewHandle<V>, mut callback: F)
1963    where
1964        V: View,
1965        V::Event: 'static,
1966        F: 'static + FnMut(&mut T, ViewHandle<V>, &V::Event, &mut ViewContext<T>),
1967    {
1968        let emitter_handle = handle.downgrade();
1969        self.subscribe(handle, move |view, payload, cx| {
1970            if let Some(emitter_handle) = emitter_handle.upgrade(cx.as_ref()) {
1971                callback(view, emitter_handle, payload, cx);
1972            }
1973        });
1974    }
1975
1976    pub fn subscribe<E, F>(&mut self, handle: &impl Handle<E>, mut callback: F)
1977    where
1978        E: Entity,
1979        E::Event: 'static,
1980        F: 'static + FnMut(&mut T, &E::Event, &mut ViewContext<T>),
1981    {
1982        self.app
1983            .subscriptions
1984            .entry(handle.id())
1985            .or_default()
1986            .push(Subscription::FromView {
1987                window_id: self.window_id,
1988                view_id: self.view_id,
1989                callback: Box::new(move |entity, payload, app, window_id, view_id| {
1990                    let entity = entity.downcast_mut().expect("downcast is type safe");
1991                    let payload = payload.downcast_ref().expect("downcast is type safe");
1992                    let mut cx = ViewContext::new(app, window_id, view_id);
1993                    callback(entity, payload, &mut cx);
1994                }),
1995            });
1996    }
1997
1998    pub fn emit(&mut self, payload: T::Event) {
1999        self.app.pending_effects.push_back(Effect::Event {
2000            entity_id: self.view_id,
2001            payload: Box::new(payload),
2002        });
2003    }
2004
2005    pub fn observe_model<S, F>(&mut self, handle: &ModelHandle<S>, mut callback: F)
2006    where
2007        S: Entity,
2008        F: 'static + FnMut(&mut T, ModelHandle<S>, &mut ViewContext<T>),
2009    {
2010        self.app
2011            .model_observations
2012            .entry(handle.id())
2013            .or_default()
2014            .push(ModelObservation::FromView {
2015                window_id: self.window_id,
2016                view_id: self.view_id,
2017                callback: Box::new(move |view, observed_id, app, window_id, view_id| {
2018                    let view = view.downcast_mut().expect("downcast is type safe");
2019                    let observed = ModelHandle::new(observed_id, &app.cx.ref_counts);
2020                    let mut cx = ViewContext::new(app, window_id, view_id);
2021                    callback(view, observed, &mut cx);
2022                }),
2023            });
2024    }
2025
2026    pub fn observe_view<S, F>(&mut self, handle: &ViewHandle<S>, mut callback: F)
2027    where
2028        S: View,
2029        F: 'static + FnMut(&mut T, ViewHandle<S>, &mut ViewContext<T>),
2030    {
2031        self.app
2032            .view_observations
2033            .entry(handle.id())
2034            .or_default()
2035            .push(ViewObservation {
2036                window_id: self.window_id,
2037                view_id: self.view_id,
2038                callback: Box::new(
2039                    move |view,
2040                          observed_view_id,
2041                          observed_window_id,
2042                          app,
2043                          observing_window_id,
2044                          observing_view_id| {
2045                        let view = view.downcast_mut().expect("downcast is type safe");
2046                        let observed_handle = ViewHandle::new(
2047                            observed_view_id,
2048                            observed_window_id,
2049                            &app.cx.ref_counts,
2050                        );
2051                        let mut cx = ViewContext::new(app, observing_window_id, observing_view_id);
2052                        callback(view, observed_handle, &mut cx);
2053                    },
2054                ),
2055            });
2056    }
2057
2058    pub fn notify(&mut self) {
2059        self.app.notify_view(self.window_id, self.view_id);
2060    }
2061
2062    pub fn propagate_action(&mut self) {
2063        self.halt_action_dispatch = false;
2064    }
2065
2066    pub fn spawn<F, Fut, S>(&self, f: F) -> Task<S>
2067    where
2068        F: FnOnce(ViewHandle<T>, AsyncAppContext) -> Fut,
2069        Fut: 'static + Future<Output = S>,
2070        S: 'static,
2071    {
2072        let handle = self.handle();
2073        self.app.spawn(|cx| f(handle, cx))
2074    }
2075}
2076
2077impl AsRef<AppContext> for &AppContext {
2078    fn as_ref(&self) -> &AppContext {
2079        self
2080    }
2081}
2082
2083impl<M> AsRef<AppContext> for ViewContext<'_, M> {
2084    fn as_ref(&self) -> &AppContext {
2085        &self.app.cx
2086    }
2087}
2088
2089impl<M> AsMut<MutableAppContext> for ViewContext<'_, M> {
2090    fn as_mut(&mut self) -> &mut MutableAppContext {
2091        self.app
2092    }
2093}
2094
2095impl<V> ReadModel for ViewContext<'_, V> {
2096    fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T {
2097        self.app.read_model(handle)
2098    }
2099}
2100
2101impl<V: View> UpdateModel for ViewContext<'_, V> {
2102    fn update_model<T, F, S>(&mut self, handle: &ModelHandle<T>, update: F) -> S
2103    where
2104        T: Entity,
2105        F: FnOnce(&mut T, &mut ModelContext<T>) -> S,
2106    {
2107        self.app.update_model(handle, update)
2108    }
2109}
2110
2111impl<V: View> ReadView for ViewContext<'_, V> {
2112    fn read_view<T: View>(&self, handle: &ViewHandle<T>) -> &T {
2113        self.app.read_view(handle)
2114    }
2115}
2116
2117impl<V: View> UpdateView for ViewContext<'_, V> {
2118    fn update_view<T, F, S>(&mut self, handle: &ViewHandle<T>, update: F) -> S
2119    where
2120        T: View,
2121        F: FnOnce(&mut T, &mut ViewContext<T>) -> S,
2122    {
2123        self.app.update_view(handle, update)
2124    }
2125}
2126
2127pub trait Handle<T> {
2128    fn id(&self) -> usize;
2129    fn location(&self) -> EntityLocation;
2130}
2131
2132#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash)]
2133pub enum EntityLocation {
2134    Model(usize),
2135    View(usize, usize),
2136}
2137
2138pub struct ModelHandle<T> {
2139    model_id: usize,
2140    model_type: PhantomData<T>,
2141    ref_counts: Arc<Mutex<RefCounts>>,
2142}
2143
2144impl<T: Entity> ModelHandle<T> {
2145    fn new(model_id: usize, ref_counts: &Arc<Mutex<RefCounts>>) -> Self {
2146        ref_counts.lock().inc_model(model_id);
2147        Self {
2148            model_id,
2149            model_type: PhantomData,
2150            ref_counts: ref_counts.clone(),
2151        }
2152    }
2153
2154    pub fn downgrade(&self) -> WeakModelHandle<T> {
2155        WeakModelHandle::new(self.model_id)
2156    }
2157
2158    pub fn id(&self) -> usize {
2159        self.model_id
2160    }
2161
2162    pub fn read<'a, C: ReadModel>(&self, cx: &'a C) -> &'a T {
2163        cx.read_model(self)
2164    }
2165
2166    pub fn read_with<'a, C, F, S>(&self, cx: &C, read: F) -> S
2167    where
2168        C: ReadModelWith,
2169        F: FnOnce(&T, &AppContext) -> S,
2170    {
2171        cx.read_model_with(self, read)
2172    }
2173
2174    pub fn update<C, F, S>(&self, cx: &mut C, update: F) -> S
2175    where
2176        C: UpdateModel,
2177        F: FnOnce(&mut T, &mut ModelContext<T>) -> S,
2178    {
2179        cx.update_model(self, update)
2180    }
2181
2182    pub fn condition(
2183        &self,
2184        cx: &TestAppContext,
2185        mut predicate: impl FnMut(&T, &AppContext) -> bool,
2186    ) -> impl Future<Output = ()> {
2187        let (tx, mut rx) = mpsc::channel(1024);
2188
2189        let mut cx = cx.cx.borrow_mut();
2190        self.update(&mut *cx, |_, cx| {
2191            cx.observe(self, {
2192                let mut tx = tx.clone();
2193                move |_, _, _| {
2194                    tx.blocking_send(()).ok();
2195                }
2196            });
2197            cx.subscribe(self, {
2198                let mut tx = tx.clone();
2199                move |_, _, _| {
2200                    tx.blocking_send(()).ok();
2201                }
2202            })
2203        });
2204
2205        let cx = cx.weak_self.as_ref().unwrap().upgrade().unwrap();
2206        let handle = self.downgrade();
2207        let duration = if std::env::var("CI").is_ok() {
2208            Duration::from_secs(5)
2209        } else {
2210            Duration::from_secs(1)
2211        };
2212
2213        async move {
2214            timeout(duration, async move {
2215                loop {
2216                    {
2217                        let cx = cx.borrow();
2218                        let cx = cx.as_ref();
2219                        if predicate(
2220                            handle
2221                                .upgrade(cx)
2222                                .expect("model dropped with pending condition")
2223                                .read(cx),
2224                            cx,
2225                        ) {
2226                            break;
2227                        }
2228                    }
2229
2230                    rx.recv()
2231                        .await
2232                        .expect("model dropped with pending condition");
2233                }
2234            })
2235            .await
2236            .expect("condition timed out");
2237        }
2238    }
2239}
2240
2241impl<T> Clone for ModelHandle<T> {
2242    fn clone(&self) -> Self {
2243        self.ref_counts.lock().inc_model(self.model_id);
2244        Self {
2245            model_id: self.model_id,
2246            model_type: PhantomData,
2247            ref_counts: self.ref_counts.clone(),
2248        }
2249    }
2250}
2251
2252impl<T> PartialEq for ModelHandle<T> {
2253    fn eq(&self, other: &Self) -> bool {
2254        self.model_id == other.model_id
2255    }
2256}
2257
2258impl<T> Eq for ModelHandle<T> {}
2259
2260impl<T> Hash for ModelHandle<T> {
2261    fn hash<H: Hasher>(&self, state: &mut H) {
2262        self.model_id.hash(state);
2263    }
2264}
2265
2266impl<T> std::borrow::Borrow<usize> for ModelHandle<T> {
2267    fn borrow(&self) -> &usize {
2268        &self.model_id
2269    }
2270}
2271
2272impl<T> Debug for ModelHandle<T> {
2273    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2274        f.debug_tuple(&format!("ModelHandle<{}>", type_name::<T>()))
2275            .field(&self.model_id)
2276            .finish()
2277    }
2278}
2279
2280unsafe impl<T> Send for ModelHandle<T> {}
2281unsafe impl<T> Sync for ModelHandle<T> {}
2282
2283impl<T> Drop for ModelHandle<T> {
2284    fn drop(&mut self) {
2285        self.ref_counts.lock().dec_model(self.model_id);
2286    }
2287}
2288
2289impl<T> Handle<T> for ModelHandle<T> {
2290    fn id(&self) -> usize {
2291        self.model_id
2292    }
2293
2294    fn location(&self) -> EntityLocation {
2295        EntityLocation::Model(self.model_id)
2296    }
2297}
2298
2299pub struct WeakModelHandle<T> {
2300    model_id: usize,
2301    model_type: PhantomData<T>,
2302}
2303
2304impl<T: Entity> WeakModelHandle<T> {
2305    fn new(model_id: usize) -> Self {
2306        Self {
2307            model_id,
2308            model_type: PhantomData,
2309        }
2310    }
2311
2312    pub fn upgrade(&self, cx: impl AsRef<AppContext>) -> Option<ModelHandle<T>> {
2313        let cx = cx.as_ref();
2314        if cx.models.contains_key(&self.model_id) {
2315            Some(ModelHandle::new(self.model_id, &cx.ref_counts))
2316        } else {
2317            None
2318        }
2319    }
2320}
2321
2322impl<T> Hash for WeakModelHandle<T> {
2323    fn hash<H: Hasher>(&self, state: &mut H) {
2324        self.model_id.hash(state)
2325    }
2326}
2327
2328impl<T> PartialEq for WeakModelHandle<T> {
2329    fn eq(&self, other: &Self) -> bool {
2330        self.model_id == other.model_id
2331    }
2332}
2333
2334impl<T> Eq for WeakModelHandle<T> {}
2335
2336impl<T> Clone for WeakModelHandle<T> {
2337    fn clone(&self) -> Self {
2338        Self {
2339            model_id: self.model_id,
2340            model_type: PhantomData,
2341        }
2342    }
2343}
2344
2345pub struct ViewHandle<T> {
2346    window_id: usize,
2347    view_id: usize,
2348    view_type: PhantomData<T>,
2349    ref_counts: Arc<Mutex<RefCounts>>,
2350}
2351
2352impl<T: View> ViewHandle<T> {
2353    fn new(window_id: usize, view_id: usize, ref_counts: &Arc<Mutex<RefCounts>>) -> Self {
2354        ref_counts.lock().inc_view(window_id, view_id);
2355        Self {
2356            window_id,
2357            view_id,
2358            view_type: PhantomData,
2359            ref_counts: ref_counts.clone(),
2360        }
2361    }
2362
2363    pub fn downgrade(&self) -> WeakViewHandle<T> {
2364        WeakViewHandle::new(self.window_id, self.view_id)
2365    }
2366
2367    pub fn window_id(&self) -> usize {
2368        self.window_id
2369    }
2370
2371    pub fn id(&self) -> usize {
2372        self.view_id
2373    }
2374
2375    pub fn read<'a, C: ReadView>(&self, cx: &'a C) -> &'a T {
2376        cx.read_view(self)
2377    }
2378
2379    pub fn read_with<C, F, S>(&self, cx: &C, read: F) -> S
2380    where
2381        C: ReadViewWith,
2382        F: FnOnce(&T, &AppContext) -> S,
2383    {
2384        cx.read_view_with(self, read)
2385    }
2386
2387    pub fn update<C, F, S>(&self, cx: &mut C, update: F) -> S
2388    where
2389        C: UpdateView,
2390        F: FnOnce(&mut T, &mut ViewContext<T>) -> S,
2391    {
2392        cx.update_view(self, update)
2393    }
2394
2395    pub fn is_focused(&self, cx: &AppContext) -> bool {
2396        cx.focused_view_id(self.window_id)
2397            .map_or(false, |focused_id| focused_id == self.view_id)
2398    }
2399
2400    pub fn condition(
2401        &self,
2402        cx: &TestAppContext,
2403        mut predicate: impl FnMut(&T, &AppContext) -> bool,
2404    ) -> impl Future<Output = ()> {
2405        let (tx, mut rx) = mpsc::channel(1024);
2406
2407        let mut cx = cx.cx.borrow_mut();
2408        self.update(&mut *cx, |_, cx| {
2409            cx.observe_view(self, {
2410                let mut tx = tx.clone();
2411                move |_, _, _| {
2412                    tx.blocking_send(()).ok();
2413                }
2414            });
2415
2416            cx.subscribe(self, {
2417                let mut tx = tx.clone();
2418                move |_, _, _| {
2419                    tx.blocking_send(()).ok();
2420                }
2421            })
2422        });
2423
2424        let cx = cx.weak_self.as_ref().unwrap().upgrade().unwrap();
2425        let handle = self.downgrade();
2426        let duration = if std::env::var("CI").is_ok() {
2427            Duration::from_secs(2)
2428        } else {
2429            Duration::from_millis(500)
2430        };
2431
2432        async move {
2433            timeout(duration, async move {
2434                loop {
2435                    {
2436                        let cx = cx.borrow();
2437                        let cx = cx.as_ref();
2438                        if predicate(
2439                            handle
2440                                .upgrade(cx)
2441                                .expect("view dropped with pending condition")
2442                                .read(cx),
2443                            cx,
2444                        ) {
2445                            break;
2446                        }
2447                    }
2448
2449                    rx.recv()
2450                        .await
2451                        .expect("view dropped with pending condition");
2452                }
2453            })
2454            .await
2455            .expect("condition timed out");
2456        }
2457    }
2458}
2459
2460impl<T> Clone for ViewHandle<T> {
2461    fn clone(&self) -> Self {
2462        self.ref_counts
2463            .lock()
2464            .inc_view(self.window_id, self.view_id);
2465        Self {
2466            window_id: self.window_id,
2467            view_id: self.view_id,
2468            view_type: PhantomData,
2469            ref_counts: self.ref_counts.clone(),
2470        }
2471    }
2472}
2473
2474impl<T> PartialEq for ViewHandle<T> {
2475    fn eq(&self, other: &Self) -> bool {
2476        self.window_id == other.window_id && self.view_id == other.view_id
2477    }
2478}
2479
2480impl<T> Eq for ViewHandle<T> {}
2481
2482impl<T> Debug for ViewHandle<T> {
2483    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2484        f.debug_struct(&format!("ViewHandle<{}>", type_name::<T>()))
2485            .field("window_id", &self.window_id)
2486            .field("view_id", &self.view_id)
2487            .finish()
2488    }
2489}
2490
2491impl<T> Drop for ViewHandle<T> {
2492    fn drop(&mut self) {
2493        self.ref_counts
2494            .lock()
2495            .dec_view(self.window_id, self.view_id);
2496    }
2497}
2498
2499impl<T> Handle<T> for ViewHandle<T> {
2500    fn id(&self) -> usize {
2501        self.view_id
2502    }
2503
2504    fn location(&self) -> EntityLocation {
2505        EntityLocation::View(self.window_id, self.view_id)
2506    }
2507}
2508
2509pub struct AnyViewHandle {
2510    window_id: usize,
2511    view_id: usize,
2512    view_type: TypeId,
2513    ref_counts: Arc<Mutex<RefCounts>>,
2514}
2515
2516impl AnyViewHandle {
2517    pub fn id(&self) -> usize {
2518        self.view_id
2519    }
2520
2521    pub fn is<T: 'static>(&self) -> bool {
2522        TypeId::of::<T>() == self.view_type
2523    }
2524
2525    pub fn downcast<T: View>(self) -> Option<ViewHandle<T>> {
2526        if self.is::<T>() {
2527            let result = Some(ViewHandle {
2528                window_id: self.window_id,
2529                view_id: self.view_id,
2530                ref_counts: self.ref_counts.clone(),
2531                view_type: PhantomData,
2532            });
2533            unsafe {
2534                Arc::decrement_strong_count(&self.ref_counts);
2535            }
2536            std::mem::forget(self);
2537            result
2538        } else {
2539            None
2540        }
2541    }
2542}
2543
2544impl Clone for AnyViewHandle {
2545    fn clone(&self) -> Self {
2546        self.ref_counts
2547            .lock()
2548            .inc_view(self.window_id, self.view_id);
2549        Self {
2550            window_id: self.window_id,
2551            view_id: self.view_id,
2552            view_type: self.view_type,
2553            ref_counts: self.ref_counts.clone(),
2554        }
2555    }
2556}
2557
2558impl<T: View> From<&ViewHandle<T>> for AnyViewHandle {
2559    fn from(handle: &ViewHandle<T>) -> Self {
2560        handle
2561            .ref_counts
2562            .lock()
2563            .inc_view(handle.window_id, handle.view_id);
2564        AnyViewHandle {
2565            window_id: handle.window_id,
2566            view_id: handle.view_id,
2567            view_type: TypeId::of::<T>(),
2568            ref_counts: handle.ref_counts.clone(),
2569        }
2570    }
2571}
2572
2573impl<T: View> From<ViewHandle<T>> for AnyViewHandle {
2574    fn from(handle: ViewHandle<T>) -> Self {
2575        let any_handle = AnyViewHandle {
2576            window_id: handle.window_id,
2577            view_id: handle.view_id,
2578            view_type: TypeId::of::<T>(),
2579            ref_counts: handle.ref_counts.clone(),
2580        };
2581        unsafe {
2582            Arc::decrement_strong_count(&handle.ref_counts);
2583        }
2584        std::mem::forget(handle);
2585        any_handle
2586    }
2587}
2588
2589impl Drop for AnyViewHandle {
2590    fn drop(&mut self) {
2591        self.ref_counts
2592            .lock()
2593            .dec_view(self.window_id, self.view_id);
2594    }
2595}
2596
2597pub struct AnyModelHandle {
2598    model_id: usize,
2599    ref_counts: Arc<Mutex<RefCounts>>,
2600}
2601
2602impl<T: Entity> From<ModelHandle<T>> for AnyModelHandle {
2603    fn from(handle: ModelHandle<T>) -> Self {
2604        handle.ref_counts.lock().inc_model(handle.model_id);
2605        Self {
2606            model_id: handle.model_id,
2607            ref_counts: handle.ref_counts.clone(),
2608        }
2609    }
2610}
2611
2612impl Drop for AnyModelHandle {
2613    fn drop(&mut self) {
2614        self.ref_counts.lock().dec_model(self.model_id);
2615    }
2616}
2617pub struct WeakViewHandle<T> {
2618    window_id: usize,
2619    view_id: usize,
2620    view_type: PhantomData<T>,
2621}
2622
2623impl<T: View> WeakViewHandle<T> {
2624    fn new(window_id: usize, view_id: usize) -> Self {
2625        Self {
2626            window_id,
2627            view_id,
2628            view_type: PhantomData,
2629        }
2630    }
2631
2632    pub fn upgrade(&self, cx: impl AsRef<AppContext>) -> Option<ViewHandle<T>> {
2633        let cx = cx.as_ref();
2634        if cx.ref_counts.lock().is_entity_alive(self.view_id) {
2635            Some(ViewHandle::new(
2636                self.window_id,
2637                self.view_id,
2638                &cx.ref_counts,
2639            ))
2640        } else {
2641            None
2642        }
2643    }
2644}
2645
2646impl<T> Clone for WeakViewHandle<T> {
2647    fn clone(&self) -> Self {
2648        Self {
2649            window_id: self.window_id,
2650            view_id: self.view_id,
2651            view_type: PhantomData,
2652        }
2653    }
2654}
2655
2656pub struct ValueHandle<T> {
2657    value_type: PhantomData<T>,
2658    tag_type_id: TypeId,
2659    id: usize,
2660    ref_counts: Weak<Mutex<RefCounts>>,
2661}
2662
2663impl<T: 'static> ValueHandle<T> {
2664    fn new(tag_type_id: TypeId, id: usize, ref_counts: &Arc<Mutex<RefCounts>>) -> Self {
2665        ref_counts.lock().inc_value(tag_type_id, id);
2666        Self {
2667            value_type: PhantomData,
2668            tag_type_id,
2669            id,
2670            ref_counts: Arc::downgrade(ref_counts),
2671        }
2672    }
2673
2674    pub fn read<R>(&self, cx: &AppContext, f: impl FnOnce(&T) -> R) -> R {
2675        f(cx.values
2676            .read()
2677            .get(&(self.tag_type_id, self.id))
2678            .unwrap()
2679            .downcast_ref()
2680            .unwrap())
2681    }
2682
2683    pub fn update<R>(&self, cx: &AppContext, f: impl FnOnce(&mut T) -> R) -> R {
2684        f(cx.values
2685            .write()
2686            .get_mut(&(self.tag_type_id, self.id))
2687            .unwrap()
2688            .downcast_mut()
2689            .unwrap())
2690    }
2691}
2692
2693impl<T> Drop for ValueHandle<T> {
2694    fn drop(&mut self) {
2695        if let Some(ref_counts) = self.ref_counts.upgrade() {
2696            ref_counts.lock().dec_value(self.tag_type_id, self.id);
2697        }
2698    }
2699}
2700
2701#[derive(Default)]
2702struct RefCounts {
2703    entity_counts: HashMap<usize, usize>,
2704    value_counts: HashMap<(TypeId, usize), usize>,
2705    dropped_models: HashSet<usize>,
2706    dropped_views: HashSet<(usize, usize)>,
2707    dropped_values: HashSet<(TypeId, usize)>,
2708}
2709
2710impl RefCounts {
2711    fn inc_model(&mut self, model_id: usize) {
2712        match self.entity_counts.entry(model_id) {
2713            Entry::Occupied(mut entry) => *entry.get_mut() += 1,
2714            Entry::Vacant(entry) => {
2715                entry.insert(1);
2716                self.dropped_models.remove(&model_id);
2717            }
2718        }
2719    }
2720
2721    fn inc_view(&mut self, window_id: usize, view_id: usize) {
2722        match self.entity_counts.entry(view_id) {
2723            Entry::Occupied(mut entry) => *entry.get_mut() += 1,
2724            Entry::Vacant(entry) => {
2725                entry.insert(1);
2726                self.dropped_views.remove(&(window_id, view_id));
2727            }
2728        }
2729    }
2730
2731    fn inc_value(&mut self, tag_type_id: TypeId, id: usize) {
2732        *self.value_counts.entry((tag_type_id, id)).or_insert(0) += 1;
2733    }
2734
2735    fn dec_model(&mut self, model_id: usize) {
2736        let count = self.entity_counts.get_mut(&model_id).unwrap();
2737        *count -= 1;
2738        if *count == 0 {
2739            self.entity_counts.remove(&model_id);
2740            self.dropped_models.insert(model_id);
2741        }
2742    }
2743
2744    fn dec_view(&mut self, window_id: usize, view_id: usize) {
2745        let count = self.entity_counts.get_mut(&view_id).unwrap();
2746        *count -= 1;
2747        if *count == 0 {
2748            self.entity_counts.remove(&view_id);
2749            self.dropped_views.insert((window_id, view_id));
2750        }
2751    }
2752
2753    fn dec_value(&mut self, tag_type_id: TypeId, id: usize) {
2754        let key = (tag_type_id, id);
2755        let count = self.value_counts.get_mut(&key).unwrap();
2756        *count -= 1;
2757        if *count == 0 {
2758            self.value_counts.remove(&key);
2759            self.dropped_values.insert(key);
2760        }
2761    }
2762
2763    fn is_entity_alive(&self, entity_id: usize) -> bool {
2764        self.entity_counts.contains_key(&entity_id)
2765    }
2766
2767    fn take_dropped(
2768        &mut self,
2769    ) -> (
2770        HashSet<usize>,
2771        HashSet<(usize, usize)>,
2772        HashSet<(TypeId, usize)>,
2773    ) {
2774        let mut dropped_models = HashSet::new();
2775        let mut dropped_views = HashSet::new();
2776        let mut dropped_values = HashSet::new();
2777        std::mem::swap(&mut self.dropped_models, &mut dropped_models);
2778        std::mem::swap(&mut self.dropped_views, &mut dropped_views);
2779        std::mem::swap(&mut self.dropped_values, &mut dropped_values);
2780        (dropped_models, dropped_views, dropped_values)
2781    }
2782}
2783
2784enum Subscription {
2785    FromModel {
2786        model_id: usize,
2787        callback: Box<dyn FnMut(&mut dyn Any, &dyn Any, &mut MutableAppContext, usize)>,
2788    },
2789    FromView {
2790        window_id: usize,
2791        view_id: usize,
2792        callback: Box<dyn FnMut(&mut dyn Any, &dyn Any, &mut MutableAppContext, usize, usize)>,
2793    },
2794}
2795
2796enum ModelObservation {
2797    FromModel {
2798        model_id: usize,
2799        callback: Box<dyn FnMut(&mut dyn Any, usize, &mut MutableAppContext, usize)>,
2800    },
2801    FromView {
2802        window_id: usize,
2803        view_id: usize,
2804        callback: Box<dyn FnMut(&mut dyn Any, usize, &mut MutableAppContext, usize, usize)>,
2805    },
2806}
2807
2808struct ViewObservation {
2809    window_id: usize,
2810    view_id: usize,
2811    callback: Box<dyn FnMut(&mut dyn Any, usize, usize, &mut MutableAppContext, usize, usize)>,
2812}
2813
2814#[cfg(test)]
2815mod tests {
2816    use super::*;
2817    use crate::elements::*;
2818    use smol::future::poll_once;
2819    use std::sync::atomic::{AtomicUsize, Ordering::SeqCst};
2820
2821    #[crate::test(self)]
2822    fn test_model_handles(cx: &mut MutableAppContext) {
2823        struct Model {
2824            other: Option<ModelHandle<Model>>,
2825            events: Vec<String>,
2826        }
2827
2828        impl Entity for Model {
2829            type Event = usize;
2830        }
2831
2832        impl Model {
2833            fn new(other: Option<ModelHandle<Self>>, cx: &mut ModelContext<Self>) -> Self {
2834                if let Some(other) = other.as_ref() {
2835                    cx.observe(other, |me, _, _| {
2836                        me.events.push("notified".into());
2837                    });
2838                    cx.subscribe(other, |me, event, _| {
2839                        me.events.push(format!("observed event {}", event));
2840                    });
2841                }
2842
2843                Self {
2844                    other,
2845                    events: Vec::new(),
2846                }
2847            }
2848        }
2849
2850        let handle_1 = cx.add_model(|cx| Model::new(None, cx));
2851        let handle_2 = cx.add_model(|cx| Model::new(Some(handle_1.clone()), cx));
2852        assert_eq!(cx.cx.models.len(), 2);
2853
2854        handle_1.update(cx, |model, cx| {
2855            model.events.push("updated".into());
2856            cx.emit(1);
2857            cx.notify();
2858            cx.emit(2);
2859        });
2860        assert_eq!(handle_1.read(cx).events, vec!["updated".to_string()]);
2861        assert_eq!(
2862            handle_2.read(cx).events,
2863            vec![
2864                "observed event 1".to_string(),
2865                "notified".to_string(),
2866                "observed event 2".to_string(),
2867            ]
2868        );
2869
2870        handle_2.update(cx, |model, _| {
2871            drop(handle_1);
2872            model.other.take();
2873        });
2874
2875        assert_eq!(cx.cx.models.len(), 1);
2876        assert!(cx.subscriptions.is_empty());
2877        assert!(cx.model_observations.is_empty());
2878    }
2879
2880    #[crate::test(self)]
2881    fn test_subscribe_and_emit_from_model(cx: &mut MutableAppContext) {
2882        #[derive(Default)]
2883        struct Model {
2884            events: Vec<usize>,
2885        }
2886
2887        impl Entity for Model {
2888            type Event = usize;
2889        }
2890
2891        let handle_1 = cx.add_model(|_| Model::default());
2892        let handle_2 = cx.add_model(|_| Model::default());
2893        let handle_2b = handle_2.clone();
2894
2895        handle_1.update(cx, |_, c| {
2896            c.subscribe(&handle_2, move |model: &mut Model, event, c| {
2897                model.events.push(*event);
2898
2899                c.subscribe(&handle_2b, |model, event, _| {
2900                    model.events.push(*event * 2);
2901                });
2902            });
2903        });
2904
2905        handle_2.update(cx, |_, c| c.emit(7));
2906        assert_eq!(handle_1.read(cx).events, vec![7]);
2907
2908        handle_2.update(cx, |_, c| c.emit(5));
2909        assert_eq!(handle_1.read(cx).events, vec![7, 10, 5]);
2910    }
2911
2912    #[crate::test(self)]
2913    fn test_observe_and_notify_from_model(cx: &mut MutableAppContext) {
2914        #[derive(Default)]
2915        struct Model {
2916            count: usize,
2917            events: Vec<usize>,
2918        }
2919
2920        impl Entity for Model {
2921            type Event = ();
2922        }
2923
2924        let handle_1 = cx.add_model(|_| Model::default());
2925        let handle_2 = cx.add_model(|_| Model::default());
2926        let handle_2b = handle_2.clone();
2927
2928        handle_1.update(cx, |_, c| {
2929            c.observe(&handle_2, move |model, observed, c| {
2930                model.events.push(observed.read(c).count);
2931                c.observe(&handle_2b, |model, observed, c| {
2932                    model.events.push(observed.read(c).count * 2);
2933                });
2934            });
2935        });
2936
2937        handle_2.update(cx, |model, c| {
2938            model.count = 7;
2939            c.notify()
2940        });
2941        assert_eq!(handle_1.read(cx).events, vec![7]);
2942
2943        handle_2.update(cx, |model, c| {
2944            model.count = 5;
2945            c.notify()
2946        });
2947        assert_eq!(handle_1.read(cx).events, vec![7, 10, 5])
2948    }
2949
2950    #[crate::test(self)]
2951    fn test_view_handles(cx: &mut MutableAppContext) {
2952        struct View {
2953            other: Option<ViewHandle<View>>,
2954            events: Vec<String>,
2955        }
2956
2957        impl Entity for View {
2958            type Event = usize;
2959        }
2960
2961        impl super::View for View {
2962            fn render<'a>(&self, _: &AppContext) -> ElementBox {
2963                Empty::new().boxed()
2964            }
2965
2966            fn ui_name() -> &'static str {
2967                "View"
2968            }
2969        }
2970
2971        impl View {
2972            fn new(other: Option<ViewHandle<View>>, cx: &mut ViewContext<Self>) -> Self {
2973                if let Some(other) = other.as_ref() {
2974                    cx.subscribe_to_view(other, |me, _, event, _| {
2975                        me.events.push(format!("observed event {}", event));
2976                    });
2977                }
2978                Self {
2979                    other,
2980                    events: Vec::new(),
2981                }
2982            }
2983        }
2984
2985        let (window_id, _) = cx.add_window(|cx| View::new(None, cx));
2986        let handle_1 = cx.add_view(window_id, |cx| View::new(None, cx));
2987        let handle_2 = cx.add_view(window_id, |cx| View::new(Some(handle_1.clone()), cx));
2988        assert_eq!(cx.cx.views.len(), 3);
2989
2990        handle_1.update(cx, |view, cx| {
2991            view.events.push("updated".into());
2992            cx.emit(1);
2993            cx.emit(2);
2994        });
2995        assert_eq!(handle_1.read(cx).events, vec!["updated".to_string()]);
2996        assert_eq!(
2997            handle_2.read(cx).events,
2998            vec![
2999                "observed event 1".to_string(),
3000                "observed event 2".to_string(),
3001            ]
3002        );
3003
3004        handle_2.update(cx, |view, _| {
3005            drop(handle_1);
3006            view.other.take();
3007        });
3008
3009        assert_eq!(cx.cx.views.len(), 2);
3010        assert!(cx.subscriptions.is_empty());
3011        assert!(cx.model_observations.is_empty());
3012    }
3013
3014    #[crate::test(self)]
3015    fn test_add_window(cx: &mut MutableAppContext) {
3016        struct View {
3017            mouse_down_count: Arc<AtomicUsize>,
3018        }
3019
3020        impl Entity for View {
3021            type Event = ();
3022        }
3023
3024        impl super::View for View {
3025            fn render<'a>(&self, _: &AppContext) -> ElementBox {
3026                let mouse_down_count = self.mouse_down_count.clone();
3027                EventHandler::new(Empty::new().boxed())
3028                    .on_mouse_down(move |_| {
3029                        mouse_down_count.fetch_add(1, SeqCst);
3030                        true
3031                    })
3032                    .boxed()
3033            }
3034
3035            fn ui_name() -> &'static str {
3036                "View"
3037            }
3038        }
3039
3040        let mouse_down_count = Arc::new(AtomicUsize::new(0));
3041        let (window_id, _) = cx.add_window(|_| View {
3042            mouse_down_count: mouse_down_count.clone(),
3043        });
3044        let presenter = cx.presenters_and_platform_windows[&window_id].0.clone();
3045        // Ensure window's root element is in a valid lifecycle state.
3046        presenter.borrow_mut().dispatch_event(
3047            Event::LeftMouseDown {
3048                position: Default::default(),
3049                cmd: false,
3050            },
3051            cx,
3052        );
3053        assert_eq!(mouse_down_count.load(SeqCst), 1);
3054    }
3055
3056    #[crate::test(self)]
3057    fn test_entity_release_hooks(cx: &mut MutableAppContext) {
3058        struct Model {
3059            released: Arc<Mutex<bool>>,
3060        }
3061
3062        struct View {
3063            released: Arc<Mutex<bool>>,
3064        }
3065
3066        impl Entity for Model {
3067            type Event = ();
3068
3069            fn release(&mut self, _: &mut MutableAppContext) {
3070                *self.released.lock() = true;
3071            }
3072        }
3073
3074        impl Entity for View {
3075            type Event = ();
3076
3077            fn release(&mut self, _: &mut MutableAppContext) {
3078                *self.released.lock() = true;
3079            }
3080        }
3081
3082        impl super::View for View {
3083            fn ui_name() -> &'static str {
3084                "View"
3085            }
3086
3087            fn render<'a>(&self, _: &AppContext) -> ElementBox {
3088                Empty::new().boxed()
3089            }
3090        }
3091
3092        let model_released = Arc::new(Mutex::new(false));
3093        let view_released = Arc::new(Mutex::new(false));
3094
3095        let model = cx.add_model(|_| Model {
3096            released: model_released.clone(),
3097        });
3098
3099        let (window_id, _) = cx.add_window(|_| View {
3100            released: view_released.clone(),
3101        });
3102
3103        assert!(!*model_released.lock());
3104        assert!(!*view_released.lock());
3105
3106        cx.update(move || {
3107            drop(model);
3108        });
3109        assert!(*model_released.lock());
3110
3111        drop(cx.remove_window(window_id));
3112        assert!(*view_released.lock());
3113    }
3114
3115    #[crate::test(self)]
3116    fn test_subscribe_and_emit_from_view(cx: &mut MutableAppContext) {
3117        #[derive(Default)]
3118        struct View {
3119            events: Vec<usize>,
3120        }
3121
3122        impl Entity for View {
3123            type Event = usize;
3124        }
3125
3126        impl super::View for View {
3127            fn render<'a>(&self, _: &AppContext) -> ElementBox {
3128                Empty::new().boxed()
3129            }
3130
3131            fn ui_name() -> &'static str {
3132                "View"
3133            }
3134        }
3135
3136        struct Model;
3137
3138        impl Entity for Model {
3139            type Event = usize;
3140        }
3141
3142        let (window_id, handle_1) = cx.add_window(|_| View::default());
3143        let handle_2 = cx.add_view(window_id, |_| View::default());
3144        let handle_2b = handle_2.clone();
3145        let handle_3 = cx.add_model(|_| Model);
3146
3147        handle_1.update(cx, |_, c| {
3148            c.subscribe_to_view(&handle_2, move |me, _, event, c| {
3149                me.events.push(*event);
3150
3151                c.subscribe_to_view(&handle_2b, |me, _, event, _| {
3152                    me.events.push(*event * 2);
3153                });
3154            });
3155
3156            c.subscribe_to_model(&handle_3, |me, _, event, _| {
3157                me.events.push(*event);
3158            })
3159        });
3160
3161        handle_2.update(cx, |_, c| c.emit(7));
3162        assert_eq!(handle_1.read(cx).events, vec![7]);
3163
3164        handle_2.update(cx, |_, c| c.emit(5));
3165        assert_eq!(handle_1.read(cx).events, vec![7, 10, 5]);
3166
3167        handle_3.update(cx, |_, c| c.emit(9));
3168        assert_eq!(handle_1.read(cx).events, vec![7, 10, 5, 9]);
3169    }
3170
3171    #[crate::test(self)]
3172    fn test_dropping_subscribers(cx: &mut MutableAppContext) {
3173        struct View;
3174
3175        impl Entity for View {
3176            type Event = ();
3177        }
3178
3179        impl super::View for View {
3180            fn render<'a>(&self, _: &AppContext) -> ElementBox {
3181                Empty::new().boxed()
3182            }
3183
3184            fn ui_name() -> &'static str {
3185                "View"
3186            }
3187        }
3188
3189        struct Model;
3190
3191        impl Entity for Model {
3192            type Event = ();
3193        }
3194
3195        let (window_id, _) = cx.add_window(|_| View);
3196        let observing_view = cx.add_view(window_id, |_| View);
3197        let emitting_view = cx.add_view(window_id, |_| View);
3198        let observing_model = cx.add_model(|_| Model);
3199        let observed_model = cx.add_model(|_| Model);
3200
3201        observing_view.update(cx, |_, cx| {
3202            cx.subscribe_to_view(&emitting_view, |_, _, _, _| {});
3203            cx.subscribe_to_model(&observed_model, |_, _, _, _| {});
3204        });
3205        observing_model.update(cx, |_, cx| {
3206            cx.subscribe(&observed_model, |_, _, _| {});
3207        });
3208
3209        cx.update(|| {
3210            drop(observing_view);
3211            drop(observing_model);
3212        });
3213
3214        emitting_view.update(cx, |_, cx| cx.emit(()));
3215        observed_model.update(cx, |_, cx| cx.emit(()));
3216    }
3217
3218    #[crate::test(self)]
3219    fn test_observe_and_notify_from_view(cx: &mut MutableAppContext) {
3220        #[derive(Default)]
3221        struct View {
3222            events: Vec<usize>,
3223        }
3224
3225        impl Entity for View {
3226            type Event = usize;
3227        }
3228
3229        impl super::View for View {
3230            fn render<'a>(&self, _: &AppContext) -> ElementBox {
3231                Empty::new().boxed()
3232            }
3233
3234            fn ui_name() -> &'static str {
3235                "View"
3236            }
3237        }
3238
3239        #[derive(Default)]
3240        struct Model {
3241            count: usize,
3242        }
3243
3244        impl Entity for Model {
3245            type Event = ();
3246        }
3247
3248        let (_, view) = cx.add_window(|_| View::default());
3249        let model = cx.add_model(|_| Model::default());
3250
3251        view.update(cx, |_, c| {
3252            c.observe_model(&model, |me, observed, c| {
3253                me.events.push(observed.read(c).count)
3254            });
3255        });
3256
3257        model.update(cx, |model, c| {
3258            model.count = 11;
3259            c.notify();
3260        });
3261        assert_eq!(view.read(cx).events, vec![11]);
3262    }
3263
3264    #[crate::test(self)]
3265    fn test_dropping_observers(cx: &mut MutableAppContext) {
3266        struct View;
3267
3268        impl Entity for View {
3269            type Event = ();
3270        }
3271
3272        impl super::View for View {
3273            fn render<'a>(&self, _: &AppContext) -> ElementBox {
3274                Empty::new().boxed()
3275            }
3276
3277            fn ui_name() -> &'static str {
3278                "View"
3279            }
3280        }
3281
3282        struct Model;
3283
3284        impl Entity for Model {
3285            type Event = ();
3286        }
3287
3288        let (window_id, _) = cx.add_window(|_| View);
3289        let observing_view = cx.add_view(window_id, |_| View);
3290        let observing_model = cx.add_model(|_| Model);
3291        let observed_model = cx.add_model(|_| Model);
3292
3293        observing_view.update(cx, |_, cx| {
3294            cx.observe_model(&observed_model, |_, _, _| {});
3295        });
3296        observing_model.update(cx, |_, cx| {
3297            cx.observe(&observed_model, |_, _, _| {});
3298        });
3299
3300        cx.update(|| {
3301            drop(observing_view);
3302            drop(observing_model);
3303        });
3304
3305        observed_model.update(cx, |_, cx| cx.notify());
3306    }
3307
3308    #[crate::test(self)]
3309    fn test_focus(cx: &mut MutableAppContext) {
3310        struct View {
3311            name: String,
3312            events: Arc<Mutex<Vec<String>>>,
3313        }
3314
3315        impl Entity for View {
3316            type Event = ();
3317        }
3318
3319        impl super::View for View {
3320            fn render<'a>(&self, _: &AppContext) -> ElementBox {
3321                Empty::new().boxed()
3322            }
3323
3324            fn ui_name() -> &'static str {
3325                "View"
3326            }
3327
3328            fn on_focus(&mut self, _: &mut ViewContext<Self>) {
3329                self.events.lock().push(format!("{} focused", &self.name));
3330            }
3331
3332            fn on_blur(&mut self, _: &mut ViewContext<Self>) {
3333                self.events.lock().push(format!("{} blurred", &self.name));
3334            }
3335        }
3336
3337        let events: Arc<Mutex<Vec<String>>> = Default::default();
3338        let (window_id, view_1) = cx.add_window(|_| View {
3339            events: events.clone(),
3340            name: "view 1".to_string(),
3341        });
3342        let view_2 = cx.add_view(window_id, |_| View {
3343            events: events.clone(),
3344            name: "view 2".to_string(),
3345        });
3346
3347        view_1.update(cx, |_, cx| cx.focus(&view_2));
3348        view_1.update(cx, |_, cx| cx.focus(&view_1));
3349        view_1.update(cx, |_, cx| cx.focus(&view_2));
3350        view_1.update(cx, |_, _| drop(view_2));
3351
3352        assert_eq!(
3353            *events.lock(),
3354            [
3355                "view 1 focused".to_string(),
3356                "view 1 blurred".to_string(),
3357                "view 2 focused".to_string(),
3358                "view 2 blurred".to_string(),
3359                "view 1 focused".to_string(),
3360                "view 1 blurred".to_string(),
3361                "view 2 focused".to_string(),
3362                "view 1 focused".to_string(),
3363            ],
3364        );
3365    }
3366
3367    #[crate::test(self)]
3368    fn test_dispatch_action(cx: &mut MutableAppContext) {
3369        struct ViewA {
3370            id: usize,
3371        }
3372
3373        impl Entity for ViewA {
3374            type Event = ();
3375        }
3376
3377        impl View for ViewA {
3378            fn render<'a>(&self, _: &AppContext) -> ElementBox {
3379                Empty::new().boxed()
3380            }
3381
3382            fn ui_name() -> &'static str {
3383                "View"
3384            }
3385        }
3386
3387        struct ViewB {
3388            id: usize,
3389        }
3390
3391        impl Entity for ViewB {
3392            type Event = ();
3393        }
3394
3395        impl View for ViewB {
3396            fn render<'a>(&self, _: &AppContext) -> ElementBox {
3397                Empty::new().boxed()
3398            }
3399
3400            fn ui_name() -> &'static str {
3401                "View"
3402            }
3403        }
3404
3405        struct ActionArg {
3406            foo: String,
3407        }
3408
3409        let actions = Rc::new(RefCell::new(Vec::new()));
3410
3411        let actions_clone = actions.clone();
3412        cx.add_global_action("action", move |_: &ActionArg, _: &mut MutableAppContext| {
3413            actions_clone.borrow_mut().push("global a".to_string());
3414        });
3415
3416        let actions_clone = actions.clone();
3417        cx.add_global_action("action", move |_: &ActionArg, _: &mut MutableAppContext| {
3418            actions_clone.borrow_mut().push("global b".to_string());
3419        });
3420
3421        let actions_clone = actions.clone();
3422        cx.add_action("action", move |view: &mut ViewA, arg: &ActionArg, cx| {
3423            assert_eq!(arg.foo, "bar");
3424            cx.propagate_action();
3425            actions_clone.borrow_mut().push(format!("{} a", view.id));
3426        });
3427
3428        let actions_clone = actions.clone();
3429        cx.add_action("action", move |view: &mut ViewA, _: &ActionArg, cx| {
3430            if view.id != 1 {
3431                cx.propagate_action();
3432            }
3433            actions_clone.borrow_mut().push(format!("{} b", view.id));
3434        });
3435
3436        let actions_clone = actions.clone();
3437        cx.add_action("action", move |view: &mut ViewB, _: &ActionArg, cx| {
3438            cx.propagate_action();
3439            actions_clone.borrow_mut().push(format!("{} c", view.id));
3440        });
3441
3442        let actions_clone = actions.clone();
3443        cx.add_action("action", move |view: &mut ViewB, _: &ActionArg, cx| {
3444            cx.propagate_action();
3445            actions_clone.borrow_mut().push(format!("{} d", view.id));
3446        });
3447
3448        let (window_id, view_1) = cx.add_window(|_| ViewA { id: 1 });
3449        let view_2 = cx.add_view(window_id, |_| ViewB { id: 2 });
3450        let view_3 = cx.add_view(window_id, |_| ViewA { id: 3 });
3451        let view_4 = cx.add_view(window_id, |_| ViewB { id: 4 });
3452
3453        cx.dispatch_action(
3454            window_id,
3455            vec![view_1.id(), view_2.id(), view_3.id(), view_4.id()],
3456            "action",
3457            ActionArg { foo: "bar".into() },
3458        );
3459
3460        assert_eq!(
3461            *actions.borrow(),
3462            vec!["4 d", "4 c", "3 b", "3 a", "2 d", "2 c", "1 b"]
3463        );
3464
3465        // Remove view_1, which doesn't propagate the action
3466        actions.borrow_mut().clear();
3467        cx.dispatch_action(
3468            window_id,
3469            vec![view_2.id(), view_3.id(), view_4.id()],
3470            "action",
3471            ActionArg { foo: "bar".into() },
3472        );
3473
3474        assert_eq!(
3475            *actions.borrow(),
3476            vec!["4 d", "4 c", "3 b", "3 a", "2 d", "2 c", "global b", "global a"]
3477        );
3478    }
3479
3480    #[crate::test(self)]
3481    fn test_dispatch_keystroke(cx: &mut MutableAppContext) {
3482        use std::cell::Cell;
3483
3484        #[derive(Clone)]
3485        struct ActionArg {
3486            key: String,
3487        }
3488
3489        struct View {
3490            id: usize,
3491            keymap_context: keymap::Context,
3492        }
3493
3494        impl Entity for View {
3495            type Event = ();
3496        }
3497
3498        impl super::View for View {
3499            fn render<'a>(&self, _: &AppContext) -> ElementBox {
3500                Empty::new().boxed()
3501            }
3502
3503            fn ui_name() -> &'static str {
3504                "View"
3505            }
3506
3507            fn keymap_context(&self, _: &AppContext) -> keymap::Context {
3508                self.keymap_context.clone()
3509            }
3510        }
3511
3512        impl View {
3513            fn new(id: usize) -> Self {
3514                View {
3515                    id,
3516                    keymap_context: keymap::Context::default(),
3517                }
3518            }
3519        }
3520
3521        let mut view_1 = View::new(1);
3522        let mut view_2 = View::new(2);
3523        let mut view_3 = View::new(3);
3524        view_1.keymap_context.set.insert("a".into());
3525        view_2.keymap_context.set.insert("b".into());
3526        view_3.keymap_context.set.insert("c".into());
3527
3528        let (window_id, view_1) = cx.add_window(|_| view_1);
3529        let view_2 = cx.add_view(window_id, |_| view_2);
3530        let view_3 = cx.add_view(window_id, |_| view_3);
3531
3532        // This keymap's only binding dispatches an action on view 2 because that view will have
3533        // "a" and "b" in its context, but not "c".
3534        let binding = keymap::Binding::new("a", "action", Some("a && b && !c"))
3535            .with_arg(ActionArg { key: "a".into() });
3536        cx.add_bindings(vec![binding]);
3537
3538        let handled_action = Rc::new(Cell::new(false));
3539        let handled_action_clone = handled_action.clone();
3540        cx.add_action("action", move |view: &mut View, arg: &ActionArg, _| {
3541            handled_action_clone.set(true);
3542            assert_eq!(view.id, 2);
3543            assert_eq!(arg.key, "a");
3544        });
3545
3546        cx.dispatch_keystroke(
3547            window_id,
3548            vec![view_1.id(), view_2.id(), view_3.id()],
3549            &Keystroke::parse("a").unwrap(),
3550        )
3551        .unwrap();
3552
3553        assert!(handled_action.get());
3554    }
3555
3556    #[crate::test(self)]
3557    async fn test_model_condition(mut cx: TestAppContext) {
3558        struct Counter(usize);
3559
3560        impl super::Entity for Counter {
3561            type Event = ();
3562        }
3563
3564        impl Counter {
3565            fn inc(&mut self, cx: &mut ModelContext<Self>) {
3566                self.0 += 1;
3567                cx.notify();
3568            }
3569        }
3570
3571        let model = cx.add_model(|_| Counter(0));
3572
3573        let condition1 = model.condition(&cx, |model, _| model.0 == 2);
3574        let condition2 = model.condition(&cx, |model, _| model.0 == 3);
3575        smol::pin!(condition1, condition2);
3576
3577        model.update(&mut cx, |model, cx| model.inc(cx));
3578        assert_eq!(poll_once(&mut condition1).await, None);
3579        assert_eq!(poll_once(&mut condition2).await, None);
3580
3581        model.update(&mut cx, |model, cx| model.inc(cx));
3582        assert_eq!(poll_once(&mut condition1).await, Some(()));
3583        assert_eq!(poll_once(&mut condition2).await, None);
3584
3585        model.update(&mut cx, |model, cx| model.inc(cx));
3586        assert_eq!(poll_once(&mut condition2).await, Some(()));
3587
3588        model.update(&mut cx, |_, cx| cx.notify());
3589    }
3590
3591    #[crate::test(self)]
3592    #[should_panic]
3593    async fn test_model_condition_timeout(mut cx: TestAppContext) {
3594        struct Model;
3595
3596        impl super::Entity for Model {
3597            type Event = ();
3598        }
3599
3600        let model = cx.add_model(|_| Model);
3601        model.condition(&cx, |_, _| false).await;
3602    }
3603
3604    #[crate::test(self)]
3605    #[should_panic(expected = "model dropped with pending condition")]
3606    async fn test_model_condition_panic_on_drop(mut cx: TestAppContext) {
3607        struct Model;
3608
3609        impl super::Entity for Model {
3610            type Event = ();
3611        }
3612
3613        let model = cx.add_model(|_| Model);
3614        let condition = model.condition(&cx, |_, _| false);
3615        cx.update(|_| drop(model));
3616        condition.await;
3617    }
3618
3619    #[crate::test(self)]
3620    async fn test_view_condition(mut cx: TestAppContext) {
3621        struct Counter(usize);
3622
3623        impl super::Entity for Counter {
3624            type Event = ();
3625        }
3626
3627        impl super::View for Counter {
3628            fn ui_name() -> &'static str {
3629                "test view"
3630            }
3631
3632            fn render(&self, _: &AppContext) -> ElementBox {
3633                Empty::new().boxed()
3634            }
3635        }
3636
3637        impl Counter {
3638            fn inc(&mut self, cx: &mut ViewContext<Self>) {
3639                self.0 += 1;
3640                cx.notify();
3641            }
3642        }
3643
3644        let (_, view) = cx.add_window(|_| Counter(0));
3645
3646        let condition1 = view.condition(&cx, |view, _| view.0 == 2);
3647        let condition2 = view.condition(&cx, |view, _| view.0 == 3);
3648        smol::pin!(condition1, condition2);
3649
3650        view.update(&mut cx, |view, cx| view.inc(cx));
3651        assert_eq!(poll_once(&mut condition1).await, None);
3652        assert_eq!(poll_once(&mut condition2).await, None);
3653
3654        view.update(&mut cx, |view, cx| view.inc(cx));
3655        assert_eq!(poll_once(&mut condition1).await, Some(()));
3656        assert_eq!(poll_once(&mut condition2).await, None);
3657
3658        view.update(&mut cx, |view, cx| view.inc(cx));
3659        assert_eq!(poll_once(&mut condition2).await, Some(()));
3660        view.update(&mut cx, |_, cx| cx.notify());
3661    }
3662
3663    #[crate::test(self)]
3664    #[should_panic]
3665    async fn test_view_condition_timeout(mut cx: TestAppContext) {
3666        struct View;
3667
3668        impl super::Entity for View {
3669            type Event = ();
3670        }
3671
3672        impl super::View for View {
3673            fn ui_name() -> &'static str {
3674                "test view"
3675            }
3676
3677            fn render(&self, _: &AppContext) -> ElementBox {
3678                Empty::new().boxed()
3679            }
3680        }
3681
3682        let (_, view) = cx.add_window(|_| View);
3683        view.condition(&cx, |_, _| false).await;
3684    }
3685
3686    #[crate::test(self)]
3687    #[should_panic(expected = "view dropped with pending condition")]
3688    async fn test_view_condition_panic_on_drop(mut cx: TestAppContext) {
3689        struct View;
3690
3691        impl super::Entity for View {
3692            type Event = ();
3693        }
3694
3695        impl super::View for View {
3696            fn ui_name() -> &'static str {
3697                "test view"
3698            }
3699
3700            fn render(&self, _: &AppContext) -> ElementBox {
3701                Empty::new().boxed()
3702            }
3703        }
3704
3705        let window_id = cx.add_window(|_| View).0;
3706        let view = cx.add_view(window_id, |_| View);
3707
3708        let condition = view.condition(&cx, |_, _| false);
3709        cx.update(|_| drop(view));
3710        condition.await;
3711    }
3712}