app.rs

   1use crate::{
   2    elements::ElementBox,
   3    executor,
   4    keymap::{self, Keystroke},
   5    platform::{self, WindowOptions},
   6    presenter::Presenter,
   7    util::{post_inc, timeout},
   8    AssetCache, AssetSource, ClipboardItem, FontCache, PathPromptOptions, TextLayoutCache,
   9};
  10use anyhow::{anyhow, Result};
  11use keymap::MatchResult;
  12use parking_lot::{Mutex, RwLock};
  13use pathfinder_geometry::{rect::RectF, vector::vec2f};
  14use platform::Event;
  15use postage::{sink::Sink as _, stream::Stream as _};
  16use smol::prelude::*;
  17use std::{
  18    any::{type_name, Any, TypeId},
  19    cell::RefCell,
  20    collections::{hash_map::Entry, HashMap, HashSet, VecDeque},
  21    fmt::{self, Debug},
  22    hash::{Hash, Hasher},
  23    marker::PhantomData,
  24    path::PathBuf,
  25    rc::{self, Rc},
  26    sync::{Arc, Weak},
  27    time::Duration,
  28};
  29
  30pub trait Entity: 'static + Send + Sync {
  31    type Event;
  32}
  33
  34pub trait View: Entity {
  35    fn ui_name() -> &'static str;
  36    fn render<'a>(&self, app: &AppContext) -> ElementBox;
  37    fn on_focus(&mut self, _ctx: &mut ViewContext<Self>) {}
  38    fn on_blur(&mut self, _ctx: &mut ViewContext<Self>) {}
  39    fn keymap_context(&self, _: &AppContext) -> keymap::Context {
  40        Self::default_keymap_context()
  41    }
  42    fn default_keymap_context() -> keymap::Context {
  43        let mut ctx = keymap::Context::default();
  44        ctx.set.insert(Self::ui_name().into());
  45        ctx
  46    }
  47}
  48
  49pub trait ReadModel {
  50    fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T;
  51}
  52
  53pub trait UpdateModel {
  54    fn update_model<T, F, S>(&mut self, handle: &ModelHandle<T>, update: F) -> S
  55    where
  56        T: Entity,
  57        F: FnOnce(&mut T, &mut ModelContext<T>) -> S;
  58}
  59
  60pub trait ReadView {
  61    fn read_view<T: View>(&self, handle: &ViewHandle<T>) -> &T;
  62}
  63
  64pub trait UpdateView {
  65    fn update_view<T, F, S>(&mut self, handle: &ViewHandle<T>, update: F) -> S
  66    where
  67        T: View,
  68        F: FnOnce(&mut T, &mut ViewContext<T>) -> S;
  69}
  70
  71pub struct Menu<'a> {
  72    pub name: &'a str,
  73    pub items: Vec<MenuItem<'a>>,
  74}
  75
  76pub enum MenuItem<'a> {
  77    Action {
  78        name: &'a str,
  79        keystroke: Option<&'a str>,
  80        action: &'a str,
  81        arg: Option<Box<dyn Any + 'static>>,
  82    },
  83    Separator,
  84}
  85
  86#[derive(Clone)]
  87pub struct App(Rc<RefCell<MutableAppContext>>);
  88
  89#[derive(Clone)]
  90pub struct TestAppContext(Rc<RefCell<MutableAppContext>>);
  91
  92impl App {
  93    pub fn test<T, A: AssetSource, F: FnOnce(&mut MutableAppContext) -> T>(
  94        asset_source: A,
  95        f: F,
  96    ) -> T {
  97        let platform = platform::test::platform();
  98        let foreground = Rc::new(executor::Foreground::test());
  99        let ctx = Rc::new(RefCell::new(MutableAppContext::new(
 100            foreground,
 101            Rc::new(platform),
 102            asset_source,
 103        )));
 104        ctx.borrow_mut().weak_self = Some(Rc::downgrade(&ctx));
 105        let mut ctx = ctx.borrow_mut();
 106        f(&mut *ctx)
 107    }
 108
 109    pub fn test_async<T, F, A: AssetSource, Fn>(asset_source: A, f: Fn) -> T
 110    where
 111        Fn: FnOnce(TestAppContext) -> F,
 112        F: Future<Output = T>,
 113    {
 114        let platform = platform::test::platform();
 115        let foreground = Rc::new(executor::Foreground::test());
 116        let ctx = TestAppContext(Rc::new(RefCell::new(MutableAppContext::new(
 117            foreground.clone(),
 118            Rc::new(platform),
 119            asset_source,
 120        ))));
 121        ctx.0.borrow_mut().weak_self = Some(Rc::downgrade(&ctx.0));
 122
 123        let future = f(ctx);
 124        smol::block_on(foreground.run(future))
 125    }
 126
 127    pub fn new(asset_source: impl AssetSource) -> Result<Self> {
 128        let platform = platform::current::platform();
 129        let foreground = Rc::new(executor::Foreground::platform(platform.dispatcher())?);
 130        let app = Self(Rc::new(RefCell::new(MutableAppContext::new(
 131            foreground,
 132            platform.clone(),
 133            asset_source,
 134        ))));
 135
 136        let ctx = app.0.clone();
 137        platform.on_menu_command(Box::new(move |command, arg| {
 138            let mut ctx = ctx.borrow_mut();
 139            if let Some(key_window_id) = ctx.platform.key_window_id() {
 140                if let Some((presenter, _)) =
 141                    ctx.presenters_and_platform_windows.get(&key_window_id)
 142                {
 143                    let presenter = presenter.clone();
 144                    let path = presenter.borrow().dispatch_path(ctx.as_ref());
 145                    ctx.dispatch_action_any(key_window_id, &path, command, arg.unwrap_or(&()));
 146                } else {
 147                    ctx.dispatch_global_action_any(command, arg.unwrap_or(&()));
 148                }
 149            } else {
 150                ctx.dispatch_global_action_any(command, arg.unwrap_or(&()));
 151            }
 152        }));
 153
 154        app.0.borrow_mut().weak_self = Some(Rc::downgrade(&app.0));
 155        Ok(app)
 156    }
 157
 158    pub fn on_become_active<F>(self, mut callback: F) -> Self
 159    where
 160        F: 'static + FnMut(&mut MutableAppContext),
 161    {
 162        let ctx = self.0.clone();
 163        self.0
 164            .borrow()
 165            .platform
 166            .on_become_active(Box::new(move || callback(&mut *ctx.borrow_mut())));
 167        self
 168    }
 169
 170    pub fn on_resign_active<F>(self, mut callback: F) -> Self
 171    where
 172        F: 'static + FnMut(&mut MutableAppContext),
 173    {
 174        let ctx = self.0.clone();
 175        self.0
 176            .borrow()
 177            .platform
 178            .on_resign_active(Box::new(move || callback(&mut *ctx.borrow_mut())));
 179        self
 180    }
 181
 182    pub fn on_event<F>(self, mut callback: F) -> Self
 183    where
 184        F: 'static + FnMut(Event, &mut MutableAppContext) -> bool,
 185    {
 186        let ctx = self.0.clone();
 187        self.0.borrow().platform.on_event(Box::new(move |event| {
 188            callback(event, &mut *ctx.borrow_mut())
 189        }));
 190        self
 191    }
 192
 193    pub fn on_open_files<F>(self, mut callback: F) -> Self
 194    where
 195        F: 'static + FnMut(Vec<PathBuf>, &mut MutableAppContext),
 196    {
 197        let ctx = self.0.clone();
 198        self.0
 199            .borrow()
 200            .platform
 201            .on_open_files(Box::new(move |paths| {
 202                callback(paths, &mut *ctx.borrow_mut())
 203            }));
 204        self
 205    }
 206
 207    pub fn run<F>(self, on_finish_launching: F)
 208    where
 209        F: 'static + FnOnce(&mut MutableAppContext),
 210    {
 211        let platform = self.0.borrow().platform.clone();
 212        platform.run(Box::new(move || {
 213            let mut ctx = self.0.borrow_mut();
 214            on_finish_launching(&mut *ctx);
 215        }))
 216    }
 217
 218    pub fn font_cache(&self) -> Arc<FontCache> {
 219        self.0.borrow().ctx.font_cache.clone()
 220    }
 221
 222    fn update<T, F: FnOnce(&mut MutableAppContext) -> T>(&mut self, callback: F) -> T {
 223        let mut state = self.0.borrow_mut();
 224        state.pending_flushes += 1;
 225        let result = callback(&mut *state);
 226        state.flush_effects();
 227        result
 228    }
 229}
 230
 231impl TestAppContext {
 232    pub fn dispatch_action<T: 'static + Any>(
 233        &self,
 234        window_id: usize,
 235        responder_chain: Vec<usize>,
 236        name: &str,
 237        arg: T,
 238    ) {
 239        self.0.borrow_mut().dispatch_action_any(
 240            window_id,
 241            &responder_chain,
 242            name,
 243            Box::new(arg).as_ref(),
 244        );
 245    }
 246
 247    pub fn dispatch_keystroke(
 248        &self,
 249        window_id: usize,
 250        responder_chain: Vec<usize>,
 251        keystroke: &Keystroke,
 252    ) -> Result<bool> {
 253        let mut state = self.0.borrow_mut();
 254        state.dispatch_keystroke(window_id, responder_chain, keystroke)
 255    }
 256
 257    pub fn add_model<T, F>(&mut self, build_model: F) -> ModelHandle<T>
 258    where
 259        T: Entity,
 260        F: FnOnce(&mut ModelContext<T>) -> T,
 261    {
 262        let mut state = self.0.borrow_mut();
 263        state.pending_flushes += 1;
 264        let handle = state.add_model(build_model);
 265        state.flush_effects();
 266        handle
 267    }
 268
 269    pub fn add_window<T, F>(&mut self, build_root_view: F) -> (usize, ViewHandle<T>)
 270    where
 271        T: View,
 272        F: FnOnce(&mut ViewContext<T>) -> T,
 273    {
 274        self.0.borrow_mut().add_window(build_root_view)
 275    }
 276
 277    pub fn window_ids(&self) -> Vec<usize> {
 278        self.0.borrow().window_ids().collect()
 279    }
 280
 281    pub fn root_view<T: View>(&self, window_id: usize) -> Option<ViewHandle<T>> {
 282        self.0.borrow().root_view(window_id)
 283    }
 284
 285    pub fn add_view<T, F>(&mut self, window_id: usize, build_view: F) -> ViewHandle<T>
 286    where
 287        T: View,
 288        F: FnOnce(&mut ViewContext<T>) -> T,
 289    {
 290        let mut state = self.0.borrow_mut();
 291        state.pending_flushes += 1;
 292        let handle = state.add_view(window_id, build_view);
 293        state.flush_effects();
 294        handle
 295    }
 296
 297    pub fn add_option_view<T, F>(
 298        &mut self,
 299        window_id: usize,
 300        build_view: F,
 301    ) -> Option<ViewHandle<T>>
 302    where
 303        T: View,
 304        F: FnOnce(&mut ViewContext<T>) -> Option<T>,
 305    {
 306        let mut state = self.0.borrow_mut();
 307        state.pending_flushes += 1;
 308        let handle = state.add_option_view(window_id, build_view);
 309        state.flush_effects();
 310        handle
 311    }
 312
 313    pub fn read<T, F: FnOnce(&AppContext) -> T>(&self, callback: F) -> T {
 314        callback(self.0.borrow().as_ref())
 315    }
 316
 317    pub fn update<T, F: FnOnce(&mut MutableAppContext) -> T>(&mut self, callback: F) -> T {
 318        let mut state = self.0.borrow_mut();
 319        // Don't increment pending flushes in order to effects to be flushed before the callback
 320        // completes, which is helpful in tests.
 321        let result = callback(&mut *state);
 322        // Flush effects after the callback just in case there are any. This can happen in edge
 323        // cases such as the closure dropping handles.
 324        state.flush_effects();
 325        result
 326    }
 327
 328    pub fn font_cache(&self) -> Arc<FontCache> {
 329        self.0.borrow().ctx.font_cache.clone()
 330    }
 331
 332    pub fn platform(&self) -> Rc<dyn platform::Platform> {
 333        self.0.borrow().platform.clone()
 334    }
 335}
 336
 337impl UpdateModel for TestAppContext {
 338    fn update_model<T, F, S>(&mut self, handle: &ModelHandle<T>, update: F) -> S
 339    where
 340        T: Entity,
 341        F: FnOnce(&mut T, &mut ModelContext<T>) -> S,
 342    {
 343        let mut state = self.0.borrow_mut();
 344        state.pending_flushes += 1;
 345        let result = state.update_model(handle, update);
 346        state.flush_effects();
 347        result
 348    }
 349}
 350
 351impl UpdateView for TestAppContext {
 352    fn update_view<T, F, S>(&mut self, handle: &ViewHandle<T>, update: F) -> S
 353    where
 354        T: View,
 355        F: FnOnce(&mut T, &mut ViewContext<T>) -> S,
 356    {
 357        let mut state = self.0.borrow_mut();
 358        state.pending_flushes += 1;
 359        let result = state.update_view(handle, update);
 360        state.flush_effects();
 361        result
 362    }
 363}
 364
 365type ActionCallback =
 366    dyn FnMut(&mut dyn AnyView, &dyn Any, &mut MutableAppContext, usize, usize) -> bool;
 367
 368type GlobalActionCallback = dyn FnMut(&dyn Any, &mut MutableAppContext);
 369
 370pub struct MutableAppContext {
 371    weak_self: Option<rc::Weak<RefCell<Self>>>,
 372    platform: Rc<dyn platform::Platform>,
 373    assets: Arc<AssetCache>,
 374    ctx: AppContext,
 375    actions: HashMap<TypeId, HashMap<String, Vec<Box<ActionCallback>>>>,
 376    global_actions: HashMap<String, Vec<Box<GlobalActionCallback>>>,
 377    keystroke_matcher: keymap::Matcher,
 378    next_entity_id: usize,
 379    next_window_id: usize,
 380    next_task_id: usize,
 381    subscriptions: HashMap<usize, Vec<Subscription>>,
 382    model_observations: HashMap<usize, Vec<ModelObservation>>,
 383    view_observations: HashMap<usize, Vec<ViewObservation>>,
 384    async_observations: HashMap<usize, postage::broadcast::Sender<()>>,
 385    presenters_and_platform_windows:
 386        HashMap<usize, (Rc<RefCell<Presenter>>, Box<dyn platform::Window>)>,
 387    debug_elements_callbacks: HashMap<usize, Box<dyn Fn(&AppContext) -> crate::json::Value>>,
 388    foreground: Rc<executor::Foreground>,
 389    future_handlers: Rc<RefCell<HashMap<usize, FutureHandler>>>,
 390    stream_handlers: Rc<RefCell<HashMap<usize, StreamHandler>>>,
 391    pending_effects: VecDeque<Effect>,
 392    pending_flushes: usize,
 393    flushing_effects: bool,
 394}
 395
 396impl MutableAppContext {
 397    pub fn new(
 398        foreground: Rc<executor::Foreground>,
 399        platform: Rc<dyn platform::Platform>,
 400        asset_source: impl AssetSource,
 401    ) -> Self {
 402        let fonts = platform.fonts();
 403        Self {
 404            weak_self: None,
 405            platform,
 406            assets: Arc::new(AssetCache::new(asset_source)),
 407            ctx: AppContext {
 408                models: Default::default(),
 409                views: Default::default(),
 410                windows: Default::default(),
 411                values: Default::default(),
 412                ref_counts: Arc::new(Mutex::new(RefCounts::default())),
 413                background: Arc::new(executor::Background::new()),
 414                thread_pool: scoped_pool::Pool::new(num_cpus::get(), "app"),
 415                font_cache: Arc::new(FontCache::new(fonts)),
 416            },
 417            actions: HashMap::new(),
 418            global_actions: HashMap::new(),
 419            keystroke_matcher: keymap::Matcher::default(),
 420            next_entity_id: 0,
 421            next_window_id: 0,
 422            next_task_id: 0,
 423            subscriptions: HashMap::new(),
 424            model_observations: HashMap::new(),
 425            view_observations: HashMap::new(),
 426            async_observations: HashMap::new(),
 427            presenters_and_platform_windows: HashMap::new(),
 428            debug_elements_callbacks: HashMap::new(),
 429            foreground,
 430            future_handlers: Default::default(),
 431            stream_handlers: Default::default(),
 432            pending_effects: VecDeque::new(),
 433            pending_flushes: 0,
 434            flushing_effects: false,
 435        }
 436    }
 437
 438    pub fn upgrade(&self) -> App {
 439        App(self.weak_self.as_ref().unwrap().upgrade().unwrap())
 440    }
 441
 442    pub fn platform(&self) -> Rc<dyn platform::Platform> {
 443        self.platform.clone()
 444    }
 445
 446    pub fn font_cache(&self) -> &Arc<FontCache> {
 447        &self.ctx.font_cache
 448    }
 449
 450    pub fn foreground_executor(&self) -> &Rc<executor::Foreground> {
 451        &self.foreground
 452    }
 453
 454    pub fn background_executor(&self) -> &Arc<executor::Background> {
 455        &self.ctx.background
 456    }
 457
 458    pub fn on_debug_elements<F>(&mut self, window_id: usize, callback: F)
 459    where
 460        F: 'static + Fn(&AppContext) -> crate::json::Value,
 461    {
 462        self.debug_elements_callbacks
 463            .insert(window_id, Box::new(callback));
 464    }
 465
 466    pub fn debug_elements(&self, window_id: usize) -> Option<crate::json::Value> {
 467        self.debug_elements_callbacks
 468            .get(&window_id)
 469            .map(|debug_elements| debug_elements(&self.ctx))
 470    }
 471
 472    pub fn add_action<S, V, T, F>(&mut self, name: S, mut handler: F)
 473    where
 474        S: Into<String>,
 475        V: View,
 476        T: Any,
 477        F: 'static + FnMut(&mut V, &T, &mut ViewContext<V>),
 478    {
 479        let name = name.into();
 480        let name_clone = name.clone();
 481        let handler = Box::new(
 482            move |view: &mut dyn AnyView,
 483                  arg: &dyn Any,
 484                  app: &mut MutableAppContext,
 485                  window_id: usize,
 486                  view_id: usize| {
 487                match arg.downcast_ref() {
 488                    Some(arg) => {
 489                        let mut ctx = ViewContext::new(app, window_id, view_id);
 490                        handler(
 491                            view.as_any_mut()
 492                                .downcast_mut()
 493                                .expect("downcast is type safe"),
 494                            arg,
 495                            &mut ctx,
 496                        );
 497                        ctx.halt_action_dispatch
 498                    }
 499                    None => {
 500                        log::error!("Could not downcast argument for action {}", name_clone);
 501                        false
 502                    }
 503                }
 504            },
 505        );
 506
 507        self.actions
 508            .entry(TypeId::of::<V>())
 509            .or_default()
 510            .entry(name)
 511            .or_default()
 512            .push(handler);
 513    }
 514
 515    pub fn add_global_action<S, T, F>(&mut self, name: S, mut handler: F)
 516    where
 517        S: Into<String>,
 518        T: 'static + Any,
 519        F: 'static + FnMut(&T, &mut MutableAppContext),
 520    {
 521        let name = name.into();
 522        let name_clone = name.clone();
 523        let handler = Box::new(move |arg: &dyn Any, app: &mut MutableAppContext| {
 524            if let Some(arg) = arg.downcast_ref() {
 525                handler(arg, app);
 526            } else {
 527                log::error!("Could not downcast argument for action {}", name_clone);
 528            }
 529        });
 530
 531        self.global_actions.entry(name).or_default().push(handler);
 532    }
 533
 534    pub fn window_ids(&self) -> impl Iterator<Item = usize> + '_ {
 535        self.ctx.windows.keys().cloned()
 536    }
 537
 538    pub fn root_view<T: View>(&self, window_id: usize) -> Option<ViewHandle<T>> {
 539        self.ctx
 540            .windows
 541            .get(&window_id)
 542            .and_then(|window| window.root_view.clone().downcast::<T>())
 543    }
 544
 545    pub fn root_view_id(&self, window_id: usize) -> Option<usize> {
 546        self.ctx.root_view_id(window_id)
 547    }
 548
 549    pub fn focused_view_id(&self, window_id: usize) -> Option<usize> {
 550        self.ctx.focused_view_id(window_id)
 551    }
 552
 553    pub fn render_view(&self, window_id: usize, view_id: usize) -> Result<ElementBox> {
 554        self.ctx.render_view(window_id, view_id)
 555    }
 556
 557    pub fn render_views(&self, window_id: usize) -> HashMap<usize, ElementBox> {
 558        self.ctx.render_views(window_id)
 559    }
 560
 561    pub fn update<T, F: FnOnce() -> T>(&mut self, callback: F) -> T {
 562        self.pending_flushes += 1;
 563        let result = callback();
 564        self.flush_effects();
 565        result
 566    }
 567
 568    pub fn set_menus(&self, menus: Vec<Menu>) {
 569        self.platform.set_menus(menus);
 570    }
 571
 572    pub fn prompt_for_paths<F>(&self, options: PathPromptOptions, done_fn: F)
 573    where
 574        F: 'static + FnOnce(Option<Vec<PathBuf>>, &mut MutableAppContext),
 575    {
 576        let app = self.weak_self.as_ref().unwrap().upgrade().unwrap();
 577        let foreground = self.foreground.clone();
 578        self.platform().prompt_for_paths(
 579            options,
 580            Box::new(move |paths| {
 581                foreground
 582                    .spawn(async move { (done_fn)(paths, &mut *app.borrow_mut()) })
 583                    .detach();
 584            }),
 585        );
 586    }
 587
 588    pub(crate) fn notify_view(&mut self, window_id: usize, view_id: usize) {
 589        self.pending_effects
 590            .push_back(Effect::ViewNotification { window_id, view_id });
 591    }
 592
 593    pub fn dispatch_action<T: 'static + Any>(
 594        &mut self,
 595        window_id: usize,
 596        responder_chain: Vec<usize>,
 597        name: &str,
 598        arg: T,
 599    ) {
 600        self.dispatch_action_any(window_id, &responder_chain, name, Box::new(arg).as_ref());
 601    }
 602
 603    pub(crate) fn dispatch_action_any(
 604        &mut self,
 605        window_id: usize,
 606        path: &[usize],
 607        name: &str,
 608        arg: &dyn Any,
 609    ) -> bool {
 610        self.pending_flushes += 1;
 611        let mut halted_dispatch = false;
 612
 613        for view_id in path.iter().rev() {
 614            if let Some(mut view) = self.ctx.views.remove(&(window_id, *view_id)) {
 615                let type_id = view.as_any().type_id();
 616
 617                if let Some((name, mut handlers)) = self
 618                    .actions
 619                    .get_mut(&type_id)
 620                    .and_then(|h| h.remove_entry(name))
 621                {
 622                    for handler in handlers.iter_mut().rev() {
 623                        let halt_dispatch = handler(view.as_mut(), arg, self, window_id, *view_id);
 624                        if halt_dispatch {
 625                            halted_dispatch = true;
 626                            break;
 627                        }
 628                    }
 629                    self.actions
 630                        .get_mut(&type_id)
 631                        .unwrap()
 632                        .insert(name, handlers);
 633                }
 634
 635                self.ctx.views.insert((window_id, *view_id), view);
 636
 637                if halted_dispatch {
 638                    break;
 639                }
 640            }
 641        }
 642
 643        if !halted_dispatch {
 644            self.dispatch_global_action_any(name, arg);
 645        }
 646
 647        self.flush_effects();
 648        halted_dispatch
 649    }
 650
 651    pub fn dispatch_global_action<T: 'static + Any>(&mut self, name: &str, arg: T) {
 652        self.dispatch_global_action_any(name, Box::new(arg).as_ref());
 653    }
 654
 655    fn dispatch_global_action_any(&mut self, name: &str, arg: &dyn Any) {
 656        if let Some((name, mut handlers)) = self.global_actions.remove_entry(name) {
 657            self.pending_flushes += 1;
 658            for handler in handlers.iter_mut().rev() {
 659                handler(arg, self);
 660            }
 661            self.global_actions.insert(name, handlers);
 662            self.flush_effects();
 663        }
 664    }
 665
 666    pub fn add_bindings<T: IntoIterator<Item = keymap::Binding>>(&mut self, bindings: T) {
 667        self.keystroke_matcher.add_bindings(bindings);
 668    }
 669
 670    pub fn dispatch_keystroke(
 671        &mut self,
 672        window_id: usize,
 673        responder_chain: Vec<usize>,
 674        keystroke: &Keystroke,
 675    ) -> Result<bool> {
 676        let mut context_chain = Vec::new();
 677        let mut context = keymap::Context::default();
 678        for view_id in &responder_chain {
 679            if let Some(view) = self.ctx.views.get(&(window_id, *view_id)) {
 680                context.extend(view.keymap_context(self.as_ref()));
 681                context_chain.push(context.clone());
 682            } else {
 683                return Err(anyhow!(
 684                    "View {} in responder chain does not exist",
 685                    view_id
 686                ));
 687            }
 688        }
 689
 690        let mut pending = false;
 691        for (i, ctx) in context_chain.iter().enumerate().rev() {
 692            match self
 693                .keystroke_matcher
 694                .push_keystroke(keystroke.clone(), responder_chain[i], ctx)
 695            {
 696                MatchResult::None => {}
 697                MatchResult::Pending => pending = true,
 698                MatchResult::Action { name, arg } => {
 699                    if self.dispatch_action_any(
 700                        window_id,
 701                        &responder_chain[0..=i],
 702                        &name,
 703                        arg.as_ref().map(|arg| arg.as_ref()).unwrap_or(&()),
 704                    ) {
 705                        return Ok(true);
 706                    }
 707                }
 708            }
 709        }
 710
 711        Ok(pending)
 712    }
 713
 714    pub fn add_model<T, F>(&mut self, build_model: F) -> ModelHandle<T>
 715    where
 716        T: Entity,
 717        F: FnOnce(&mut ModelContext<T>) -> T,
 718    {
 719        self.pending_flushes += 1;
 720        let model_id = post_inc(&mut self.next_entity_id);
 721        let handle = ModelHandle::new(model_id, &self.ctx.ref_counts);
 722        let mut ctx = ModelContext::new(self, model_id);
 723        let model = build_model(&mut ctx);
 724        self.ctx.models.insert(model_id, Box::new(model));
 725        self.flush_effects();
 726        handle
 727    }
 728
 729    pub fn add_window<T, F>(&mut self, build_root_view: F) -> (usize, ViewHandle<T>)
 730    where
 731        T: View,
 732        F: FnOnce(&mut ViewContext<T>) -> T,
 733    {
 734        self.pending_flushes += 1;
 735        let window_id = post_inc(&mut self.next_window_id);
 736        let root_view = self.add_view(window_id, build_root_view);
 737        self.ctx.windows.insert(
 738            window_id,
 739            Window {
 740                root_view: root_view.clone().into(),
 741                focused_view_id: root_view.id(),
 742                invalidation: None,
 743            },
 744        );
 745        self.open_platform_window(window_id);
 746        self.flush_effects();
 747
 748        (window_id, root_view)
 749    }
 750
 751    pub fn remove_window(&mut self, window_id: usize) {
 752        self.ctx.windows.remove(&window_id);
 753        self.presenters_and_platform_windows.remove(&window_id);
 754        self.remove_dropped_entities();
 755    }
 756
 757    fn open_platform_window(&mut self, window_id: usize) {
 758        let mut window = self.platform.open_window(
 759            window_id,
 760            WindowOptions {
 761                bounds: RectF::new(vec2f(0., 0.), vec2f(1024., 768.)),
 762                title: "Zed".into(),
 763            },
 764            self.foreground.clone(),
 765        );
 766        let text_layout_cache = TextLayoutCache::new(self.platform.fonts());
 767        let presenter = Rc::new(RefCell::new(Presenter::new(
 768            window_id,
 769            self.ctx.font_cache.clone(),
 770            text_layout_cache,
 771            self.assets.clone(),
 772            self,
 773        )));
 774
 775        {
 776            let mut app = self.upgrade();
 777            let presenter = presenter.clone();
 778            window.on_event(Box::new(move |event| {
 779                app.update(|ctx| {
 780                    if let Event::KeyDown { keystroke, .. } = &event {
 781                        if ctx
 782                            .dispatch_keystroke(
 783                                window_id,
 784                                presenter.borrow().dispatch_path(ctx.as_ref()),
 785                                keystroke,
 786                            )
 787                            .unwrap()
 788                        {
 789                            return;
 790                        }
 791                    }
 792
 793                    presenter.borrow_mut().dispatch_event(event, ctx);
 794                })
 795            }));
 796        }
 797
 798        {
 799            let mut app = self.upgrade();
 800            let presenter = presenter.clone();
 801            window.on_resize(Box::new(move |window| {
 802                app.update(|ctx| {
 803                    let scene = presenter.borrow_mut().build_scene(
 804                        window.size(),
 805                        window.scale_factor(),
 806                        ctx,
 807                    );
 808                    window.present_scene(scene);
 809                })
 810            }));
 811        }
 812
 813        {
 814            let mut app = self.upgrade();
 815            window.on_close(Box::new(move || {
 816                app.update(|ctx| ctx.remove_window(window_id));
 817            }));
 818        }
 819
 820        self.presenters_and_platform_windows
 821            .insert(window_id, (presenter.clone(), window));
 822
 823        self.on_debug_elements(window_id, move |ctx| {
 824            presenter.borrow().debug_elements(ctx).unwrap()
 825        });
 826    }
 827
 828    pub fn add_view<T, F>(&mut self, window_id: usize, build_view: F) -> ViewHandle<T>
 829    where
 830        T: View,
 831        F: FnOnce(&mut ViewContext<T>) -> T,
 832    {
 833        self.add_option_view(window_id, |ctx| Some(build_view(ctx)))
 834            .unwrap()
 835    }
 836
 837    pub fn add_option_view<T, F>(
 838        &mut self,
 839        window_id: usize,
 840        build_view: F,
 841    ) -> Option<ViewHandle<T>>
 842    where
 843        T: View,
 844        F: FnOnce(&mut ViewContext<T>) -> Option<T>,
 845    {
 846        let view_id = post_inc(&mut self.next_entity_id);
 847        self.pending_flushes += 1;
 848        let handle = ViewHandle::new(window_id, view_id, &self.ctx.ref_counts);
 849        let mut ctx = ViewContext::new(self, window_id, view_id);
 850        let handle = if let Some(view) = build_view(&mut ctx) {
 851            self.ctx.views.insert((window_id, view_id), Box::new(view));
 852            if let Some(window) = self.ctx.windows.get_mut(&window_id) {
 853                window
 854                    .invalidation
 855                    .get_or_insert_with(Default::default)
 856                    .updated
 857                    .insert(view_id);
 858            }
 859            Some(handle)
 860        } else {
 861            None
 862        };
 863        self.flush_effects();
 864        handle
 865    }
 866
 867    fn remove_dropped_entities(&mut self) {
 868        loop {
 869            let (dropped_models, dropped_views, dropped_values) =
 870                self.ctx.ref_counts.lock().take_dropped();
 871            if dropped_models.is_empty() && dropped_views.is_empty() && dropped_values.is_empty() {
 872                break;
 873            }
 874
 875            for model_id in dropped_models {
 876                self.ctx.models.remove(&model_id);
 877                self.subscriptions.remove(&model_id);
 878                self.model_observations.remove(&model_id);
 879                self.async_observations.remove(&model_id);
 880            }
 881
 882            for (window_id, view_id) in dropped_views {
 883                self.subscriptions.remove(&view_id);
 884                self.model_observations.remove(&view_id);
 885                self.async_observations.remove(&view_id);
 886                self.ctx.views.remove(&(window_id, view_id));
 887                let change_focus_to = self.ctx.windows.get_mut(&window_id).and_then(|window| {
 888                    window
 889                        .invalidation
 890                        .get_or_insert_with(Default::default)
 891                        .removed
 892                        .push(view_id);
 893                    if window.focused_view_id == view_id {
 894                        Some(window.root_view.id())
 895                    } else {
 896                        None
 897                    }
 898                });
 899
 900                if let Some(view_id) = change_focus_to {
 901                    self.focus(window_id, view_id);
 902                }
 903            }
 904
 905            let mut values = self.ctx.values.write();
 906            for key in dropped_values {
 907                values.remove(&key);
 908            }
 909        }
 910    }
 911
 912    fn flush_effects(&mut self) {
 913        self.pending_flushes = self.pending_flushes.saturating_sub(1);
 914
 915        if !self.flushing_effects && self.pending_flushes == 0 {
 916            self.flushing_effects = true;
 917
 918            loop {
 919                if let Some(effect) = self.pending_effects.pop_front() {
 920                    match effect {
 921                        Effect::Event { entity_id, payload } => self.emit_event(entity_id, payload),
 922                        Effect::ModelNotification { model_id } => {
 923                            self.notify_model_observers(model_id)
 924                        }
 925                        Effect::ViewNotification { window_id, view_id } => {
 926                            self.notify_view_observers(window_id, view_id)
 927                        }
 928                        Effect::Focus { window_id, view_id } => {
 929                            self.focus(window_id, view_id);
 930                        }
 931                    }
 932                } else {
 933                    self.remove_dropped_entities();
 934                    self.update_windows();
 935
 936                    if self.pending_effects.is_empty() {
 937                        self.flushing_effects = false;
 938
 939                        for (key, view) in &self.ctx.views {
 940                            log::info!("{:?} {}", key, view.ui_name());
 941                        }
 942
 943                        break;
 944                    }
 945                }
 946            }
 947        }
 948    }
 949
 950    fn update_windows(&mut self) {
 951        let mut invalidations = HashMap::new();
 952        for (window_id, window) in &mut self.ctx.windows {
 953            if let Some(invalidation) = window.invalidation.take() {
 954                invalidations.insert(*window_id, invalidation);
 955            }
 956        }
 957
 958        for (window_id, invalidation) in invalidations {
 959            if let Some((presenter, mut window)) =
 960                self.presenters_and_platform_windows.remove(&window_id)
 961            {
 962                {
 963                    let mut presenter = presenter.borrow_mut();
 964                    presenter.invalidate(invalidation, self.as_ref());
 965                    let scene = presenter.build_scene(window.size(), window.scale_factor(), self);
 966                    window.present_scene(scene);
 967                }
 968                self.presenters_and_platform_windows
 969                    .insert(window_id, (presenter, window));
 970            }
 971        }
 972    }
 973
 974    fn emit_event(&mut self, entity_id: usize, payload: Box<dyn Any>) {
 975        if let Some(subscriptions) = self.subscriptions.remove(&entity_id) {
 976            for mut subscription in subscriptions {
 977                let alive = match &mut subscription {
 978                    Subscription::FromModel { model_id, callback } => {
 979                        if let Some(mut model) = self.ctx.models.remove(model_id) {
 980                            callback(model.as_any_mut(), payload.as_ref(), self, *model_id);
 981                            self.ctx.models.insert(*model_id, model);
 982                            true
 983                        } else {
 984                            false
 985                        }
 986                    }
 987                    Subscription::FromView {
 988                        window_id,
 989                        view_id,
 990                        callback,
 991                    } => {
 992                        if let Some(mut view) = self.ctx.views.remove(&(*window_id, *view_id)) {
 993                            callback(
 994                                view.as_any_mut(),
 995                                payload.as_ref(),
 996                                self,
 997                                *window_id,
 998                                *view_id,
 999                            );
1000                            self.ctx.views.insert((*window_id, *view_id), view);
1001                            true
1002                        } else {
1003                            false
1004                        }
1005                    }
1006                };
1007
1008                if alive {
1009                    self.subscriptions
1010                        .entry(entity_id)
1011                        .or_default()
1012                        .push(subscription);
1013                }
1014            }
1015        }
1016    }
1017
1018    fn notify_model_observers(&mut self, observed_id: usize) {
1019        if let Some(observations) = self.model_observations.remove(&observed_id) {
1020            if self.ctx.models.contains_key(&observed_id) {
1021                for mut observation in observations {
1022                    let alive = match &mut observation {
1023                        ModelObservation::FromModel { model_id, callback } => {
1024                            if let Some(mut model) = self.ctx.models.remove(model_id) {
1025                                callback(model.as_any_mut(), observed_id, self, *model_id);
1026                                self.ctx.models.insert(*model_id, model);
1027                                true
1028                            } else {
1029                                false
1030                            }
1031                        }
1032                        ModelObservation::FromView {
1033                            window_id,
1034                            view_id,
1035                            callback,
1036                        } => {
1037                            if let Some(mut view) = self.ctx.views.remove(&(*window_id, *view_id)) {
1038                                callback(
1039                                    view.as_any_mut(),
1040                                    observed_id,
1041                                    self,
1042                                    *window_id,
1043                                    *view_id,
1044                                );
1045                                self.ctx.views.insert((*window_id, *view_id), view);
1046                                true
1047                            } else {
1048                                false
1049                            }
1050                        }
1051                    };
1052
1053                    if alive {
1054                        self.model_observations
1055                            .entry(observed_id)
1056                            .or_default()
1057                            .push(observation);
1058                    }
1059                }
1060            }
1061        }
1062
1063        if let Entry::Occupied(mut entry) = self.async_observations.entry(observed_id) {
1064            if entry.get_mut().blocking_send(()).is_err() {
1065                entry.remove_entry();
1066            }
1067        }
1068    }
1069
1070    fn notify_view_observers(&mut self, window_id: usize, view_id: usize) {
1071        if let Some(window) = self.ctx.windows.get_mut(&window_id) {
1072            window
1073                .invalidation
1074                .get_or_insert_with(Default::default)
1075                .updated
1076                .insert(view_id);
1077        }
1078
1079        if let Some(observations) = self.view_observations.remove(&view_id) {
1080            if self.ctx.models.contains_key(&view_id) {
1081                for mut observation in observations {
1082                    let alive = if let Some(mut view) = self
1083                        .ctx
1084                        .views
1085                        .remove(&(observation.window_id, observation.view_id))
1086                    {
1087                        (observation.callback)(
1088                            view.as_any_mut(),
1089                            view_id,
1090                            window_id,
1091                            self,
1092                            observation.window_id,
1093                            observation.view_id,
1094                        );
1095                        self.ctx
1096                            .views
1097                            .insert((observation.window_id, observation.view_id), view);
1098                        true
1099                    } else {
1100                        false
1101                    };
1102
1103                    if alive {
1104                        self.view_observations
1105                            .entry(view_id)
1106                            .or_default()
1107                            .push(observation);
1108                    }
1109                }
1110            }
1111        }
1112
1113        if let Entry::Occupied(mut entry) = self.async_observations.entry(view_id) {
1114            if entry.get_mut().blocking_send(()).is_err() {
1115                entry.remove_entry();
1116            }
1117        }
1118    }
1119
1120    fn focus(&mut self, window_id: usize, focused_id: usize) {
1121        if self
1122            .ctx
1123            .windows
1124            .get(&window_id)
1125            .map(|w| w.focused_view_id)
1126            .map_or(false, |cur_focused| cur_focused == focused_id)
1127        {
1128            return;
1129        }
1130
1131        self.pending_flushes += 1;
1132
1133        let blurred_id = self.ctx.windows.get_mut(&window_id).map(|window| {
1134            let blurred_id = window.focused_view_id;
1135            window.focused_view_id = focused_id;
1136            blurred_id
1137        });
1138
1139        if let Some(blurred_id) = blurred_id {
1140            if let Some(mut blurred_view) = self.ctx.views.remove(&(window_id, blurred_id)) {
1141                blurred_view.on_blur(self, window_id, blurred_id);
1142                self.ctx.views.insert((window_id, blurred_id), blurred_view);
1143            }
1144        }
1145
1146        if let Some(mut focused_view) = self.ctx.views.remove(&(window_id, focused_id)) {
1147            focused_view.on_focus(self, window_id, focused_id);
1148            self.ctx.views.insert((window_id, focused_id), focused_view);
1149        }
1150
1151        self.flush_effects();
1152    }
1153
1154    fn spawn<F, T>(&mut self, spawner: Spawner, future: F) -> EntityTask<T>
1155    where
1156        F: 'static + Future,
1157        T: 'static,
1158    {
1159        let task_id = post_inc(&mut self.next_task_id);
1160        let app = self.weak_self.as_ref().unwrap().upgrade().unwrap();
1161        let task = {
1162            let app = app.clone();
1163            self.foreground.spawn(async move {
1164                let output = future.await;
1165                app.borrow_mut()
1166                    .handle_future_output(task_id, Box::new(output))
1167                    .map(|output| *output.downcast::<T>().unwrap())
1168            })
1169        };
1170        EntityTask::new(
1171            task_id,
1172            task,
1173            spawner,
1174            TaskHandlerMap::Future(self.future_handlers.clone()),
1175        )
1176    }
1177
1178    fn spawn_stream<F, T>(&mut self, spawner: Spawner, mut stream: F) -> EntityTask<T>
1179    where
1180        F: 'static + Stream + Unpin,
1181        T: 'static,
1182    {
1183        let task_id = post_inc(&mut self.next_task_id);
1184        let app = self.weak_self.as_ref().unwrap().upgrade().unwrap();
1185        let task = self.foreground.spawn(async move {
1186            loop {
1187                match stream.next().await {
1188                    Some(item) => {
1189                        let mut app = app.borrow_mut();
1190                        if app.handle_stream_item(task_id, Box::new(item)) {
1191                            break;
1192                        }
1193                    }
1194                    None => {
1195                        break;
1196                    }
1197                }
1198            }
1199
1200            app.borrow_mut()
1201                .stream_completed(task_id)
1202                .map(|output| *output.downcast::<T>().unwrap())
1203        });
1204
1205        EntityTask::new(
1206            task_id,
1207            task,
1208            spawner,
1209            TaskHandlerMap::Stream(self.stream_handlers.clone()),
1210        )
1211    }
1212
1213    fn handle_future_output(
1214        &mut self,
1215        task_id: usize,
1216        output: Box<dyn Any>,
1217    ) -> Option<Box<dyn Any>> {
1218        self.pending_flushes += 1;
1219        let future_callback = self.future_handlers.borrow_mut().remove(&task_id).unwrap();
1220        let result = future_callback(output, self);
1221        self.flush_effects();
1222        result
1223    }
1224
1225    fn handle_stream_item(&mut self, task_id: usize, output: Box<dyn Any>) -> bool {
1226        self.pending_flushes += 1;
1227
1228        let mut handler = self.stream_handlers.borrow_mut().remove(&task_id).unwrap();
1229        let halt = (handler.item_callback)(output, self);
1230        self.stream_handlers.borrow_mut().insert(task_id, handler);
1231
1232        self.flush_effects();
1233        halt
1234    }
1235
1236    fn stream_completed(&mut self, task_id: usize) -> Option<Box<dyn Any>> {
1237        self.pending_flushes += 1;
1238
1239        let handler = self.stream_handlers.borrow_mut().remove(&task_id).unwrap();
1240        let result = (handler.done_callback)(self);
1241
1242        self.flush_effects();
1243        result
1244    }
1245
1246    pub fn write_to_clipboard(&self, item: ClipboardItem) {
1247        self.platform.write_to_clipboard(item);
1248    }
1249
1250    pub fn read_from_clipboard(&self) -> Option<ClipboardItem> {
1251        self.platform.read_from_clipboard()
1252    }
1253}
1254
1255impl ReadModel for MutableAppContext {
1256    fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T {
1257        if let Some(model) = self.ctx.models.get(&handle.model_id) {
1258            model
1259                .as_any()
1260                .downcast_ref()
1261                .expect("downcast is type safe")
1262        } else {
1263            panic!("circular model reference");
1264        }
1265    }
1266}
1267
1268impl UpdateModel for MutableAppContext {
1269    fn update_model<T, F, S>(&mut self, handle: &ModelHandle<T>, update: F) -> S
1270    where
1271        T: Entity,
1272        F: FnOnce(&mut T, &mut ModelContext<T>) -> S,
1273    {
1274        if let Some(mut model) = self.ctx.models.remove(&handle.model_id) {
1275            self.pending_flushes += 1;
1276            let mut ctx = ModelContext::new(self, handle.model_id);
1277            let result = update(
1278                model
1279                    .as_any_mut()
1280                    .downcast_mut()
1281                    .expect("downcast is type safe"),
1282                &mut ctx,
1283            );
1284            self.ctx.models.insert(handle.model_id, model);
1285            self.flush_effects();
1286            result
1287        } else {
1288            panic!("circular model update");
1289        }
1290    }
1291}
1292
1293impl ReadView for MutableAppContext {
1294    fn read_view<T: View>(&self, handle: &ViewHandle<T>) -> &T {
1295        if let Some(view) = self.ctx.views.get(&(handle.window_id, handle.view_id)) {
1296            view.as_any().downcast_ref().expect("downcast is type safe")
1297        } else {
1298            panic!("circular view reference");
1299        }
1300    }
1301}
1302
1303impl UpdateView for MutableAppContext {
1304    fn update_view<T, F, S>(&mut self, handle: &ViewHandle<T>, update: F) -> S
1305    where
1306        T: View,
1307        F: FnOnce(&mut T, &mut ViewContext<T>) -> S,
1308    {
1309        self.pending_flushes += 1;
1310        let mut view = self
1311            .ctx
1312            .views
1313            .remove(&(handle.window_id, handle.view_id))
1314            .expect("circular view update");
1315
1316        let mut ctx = ViewContext::new(self, handle.window_id, handle.view_id);
1317        let result = update(
1318            view.as_any_mut()
1319                .downcast_mut()
1320                .expect("downcast is type safe"),
1321            &mut ctx,
1322        );
1323        self.ctx
1324            .views
1325            .insert((handle.window_id, handle.view_id), view);
1326        self.flush_effects();
1327        result
1328    }
1329}
1330
1331impl AsRef<AppContext> for MutableAppContext {
1332    fn as_ref(&self) -> &AppContext {
1333        &self.ctx
1334    }
1335}
1336
1337pub struct AppContext {
1338    models: HashMap<usize, Box<dyn AnyModel>>,
1339    views: HashMap<(usize, usize), Box<dyn AnyView>>,
1340    windows: HashMap<usize, Window>,
1341    values: RwLock<HashMap<(TypeId, usize), Box<dyn Any>>>,
1342    background: Arc<executor::Background>,
1343    ref_counts: Arc<Mutex<RefCounts>>,
1344    thread_pool: scoped_pool::Pool,
1345    font_cache: Arc<FontCache>,
1346}
1347
1348impl AppContext {
1349    pub fn root_view_id(&self, window_id: usize) -> Option<usize> {
1350        self.windows
1351            .get(&window_id)
1352            .map(|window| window.root_view.id())
1353    }
1354
1355    pub fn focused_view_id(&self, window_id: usize) -> Option<usize> {
1356        self.windows
1357            .get(&window_id)
1358            .map(|window| window.focused_view_id)
1359    }
1360
1361    pub fn render_view(&self, window_id: usize, view_id: usize) -> Result<ElementBox> {
1362        self.views
1363            .get(&(window_id, view_id))
1364            .map(|v| v.render(self))
1365            .ok_or(anyhow!("view not found"))
1366    }
1367
1368    pub fn render_views(&self, window_id: usize) -> HashMap<usize, ElementBox> {
1369        self.views
1370            .iter()
1371            .filter_map(|((win_id, view_id), view)| {
1372                if *win_id == window_id {
1373                    Some((*view_id, view.render(self)))
1374                } else {
1375                    None
1376                }
1377            })
1378            .collect::<HashMap<_, ElementBox>>()
1379    }
1380
1381    pub fn background_executor(&self) -> &Arc<executor::Background> {
1382        &self.background
1383    }
1384
1385    pub fn font_cache(&self) -> &FontCache {
1386        &self.font_cache
1387    }
1388
1389    pub fn thread_pool(&self) -> &scoped_pool::Pool {
1390        &self.thread_pool
1391    }
1392
1393    pub fn value<Tag: 'static, T: 'static + Default>(&self, id: usize) -> ValueHandle<T> {
1394        let key = (TypeId::of::<Tag>(), id);
1395        let mut values = self.values.write();
1396        values.entry(key).or_insert_with(|| Box::new(T::default()));
1397        ValueHandle::new(TypeId::of::<Tag>(), id, &self.ref_counts)
1398    }
1399}
1400
1401impl ReadModel for AppContext {
1402    fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T {
1403        if let Some(model) = self.models.get(&handle.model_id) {
1404            model
1405                .as_any()
1406                .downcast_ref()
1407                .expect("downcast should be type safe")
1408        } else {
1409            panic!("circular model reference");
1410        }
1411    }
1412}
1413
1414impl ReadView for AppContext {
1415    fn read_view<T: View>(&self, handle: &ViewHandle<T>) -> &T {
1416        if let Some(view) = self.views.get(&(handle.window_id, handle.view_id)) {
1417            view.as_any()
1418                .downcast_ref()
1419                .expect("downcast should be type safe")
1420        } else {
1421            panic!("circular view reference");
1422        }
1423    }
1424}
1425
1426struct Window {
1427    root_view: AnyViewHandle,
1428    focused_view_id: usize,
1429    invalidation: Option<WindowInvalidation>,
1430}
1431
1432#[derive(Default, Clone)]
1433pub struct WindowInvalidation {
1434    pub updated: HashSet<usize>,
1435    pub removed: Vec<usize>,
1436}
1437
1438pub enum Effect {
1439    Event {
1440        entity_id: usize,
1441        payload: Box<dyn Any>,
1442    },
1443    ModelNotification {
1444        model_id: usize,
1445    },
1446    ViewNotification {
1447        window_id: usize,
1448        view_id: usize,
1449    },
1450    Focus {
1451        window_id: usize,
1452        view_id: usize,
1453    },
1454}
1455
1456pub trait AnyModel: Send + Sync {
1457    fn as_any(&self) -> &dyn Any;
1458    fn as_any_mut(&mut self) -> &mut dyn Any;
1459}
1460
1461impl<T> AnyModel for T
1462where
1463    T: Entity,
1464{
1465    fn as_any(&self) -> &dyn Any {
1466        self
1467    }
1468
1469    fn as_any_mut(&mut self) -> &mut dyn Any {
1470        self
1471    }
1472}
1473
1474pub trait AnyView: Send + Sync {
1475    fn as_any(&self) -> &dyn Any;
1476    fn as_any_mut(&mut self) -> &mut dyn Any;
1477    fn ui_name(&self) -> &'static str;
1478    fn render<'a>(&self, app: &AppContext) -> ElementBox;
1479    fn on_focus(&mut self, app: &mut MutableAppContext, window_id: usize, view_id: usize);
1480    fn on_blur(&mut self, app: &mut MutableAppContext, window_id: usize, view_id: usize);
1481    fn keymap_context(&self, app: &AppContext) -> keymap::Context;
1482}
1483
1484impl<T> AnyView for T
1485where
1486    T: View,
1487{
1488    fn as_any(&self) -> &dyn Any {
1489        self
1490    }
1491
1492    fn as_any_mut(&mut self) -> &mut dyn Any {
1493        self
1494    }
1495
1496    fn ui_name(&self) -> &'static str {
1497        T::ui_name()
1498    }
1499
1500    fn render<'a>(&self, app: &AppContext) -> ElementBox {
1501        View::render(self, app)
1502    }
1503
1504    fn on_focus(&mut self, app: &mut MutableAppContext, window_id: usize, view_id: usize) {
1505        let mut ctx = ViewContext::new(app, window_id, view_id);
1506        View::on_focus(self, &mut ctx);
1507    }
1508
1509    fn on_blur(&mut self, app: &mut MutableAppContext, window_id: usize, view_id: usize) {
1510        let mut ctx = ViewContext::new(app, window_id, view_id);
1511        View::on_blur(self, &mut ctx);
1512    }
1513
1514    fn keymap_context(&self, app: &AppContext) -> keymap::Context {
1515        View::keymap_context(self, app)
1516    }
1517}
1518
1519pub struct ModelContext<'a, T: ?Sized> {
1520    app: &'a mut MutableAppContext,
1521    model_id: usize,
1522    model_type: PhantomData<T>,
1523    halt_stream: bool,
1524}
1525
1526impl<'a, T: Entity> ModelContext<'a, T> {
1527    fn new(app: &'a mut MutableAppContext, model_id: usize) -> Self {
1528        Self {
1529            app,
1530            model_id,
1531            model_type: PhantomData,
1532            halt_stream: false,
1533        }
1534    }
1535
1536    pub fn background_executor(&self) -> &Arc<executor::Background> {
1537        &self.app.ctx.background
1538    }
1539
1540    pub fn thread_pool(&self) -> &scoped_pool::Pool {
1541        &self.app.ctx.thread_pool
1542    }
1543
1544    pub fn halt_stream(&mut self) {
1545        self.halt_stream = true;
1546    }
1547
1548    pub fn model_id(&self) -> usize {
1549        self.model_id
1550    }
1551
1552    pub fn add_model<S, F>(&mut self, build_model: F) -> ModelHandle<S>
1553    where
1554        S: Entity,
1555        F: FnOnce(&mut ModelContext<S>) -> S,
1556    {
1557        self.app.add_model(build_model)
1558    }
1559
1560    pub fn subscribe<S: Entity, F>(&mut self, handle: &ModelHandle<S>, mut callback: F)
1561    where
1562        S::Event: 'static,
1563        F: 'static + FnMut(&mut T, &S::Event, &mut ModelContext<T>),
1564    {
1565        self.app
1566            .subscriptions
1567            .entry(handle.model_id)
1568            .or_default()
1569            .push(Subscription::FromModel {
1570                model_id: self.model_id,
1571                callback: Box::new(move |model, payload, app, model_id| {
1572                    let model = model.downcast_mut().expect("downcast is type safe");
1573                    let payload = payload.downcast_ref().expect("downcast is type safe");
1574                    let mut ctx = ModelContext::new(app, model_id);
1575                    callback(model, payload, &mut ctx);
1576                }),
1577            });
1578    }
1579
1580    pub fn emit(&mut self, payload: T::Event) {
1581        self.app.pending_effects.push_back(Effect::Event {
1582            entity_id: self.model_id,
1583            payload: Box::new(payload),
1584        });
1585    }
1586
1587    pub fn observe<S, F>(&mut self, handle: &ModelHandle<S>, mut callback: F)
1588    where
1589        S: Entity,
1590        F: 'static + FnMut(&mut T, ModelHandle<S>, &mut ModelContext<T>),
1591    {
1592        self.app
1593            .model_observations
1594            .entry(handle.model_id)
1595            .or_default()
1596            .push(ModelObservation::FromModel {
1597                model_id: self.model_id,
1598                callback: Box::new(move |model, observed_id, app, model_id| {
1599                    let model = model.downcast_mut().expect("downcast is type safe");
1600                    let observed = ModelHandle::new(observed_id, &app.ctx.ref_counts);
1601                    let mut ctx = ModelContext::new(app, model_id);
1602                    callback(model, observed, &mut ctx);
1603                }),
1604            });
1605    }
1606
1607    pub fn notify(&mut self) {
1608        self.app
1609            .pending_effects
1610            .push_back(Effect::ModelNotification {
1611                model_id: self.model_id,
1612            });
1613    }
1614
1615    fn handle(&self) -> ModelHandle<T> {
1616        ModelHandle::new(self.model_id, &self.app.ctx.ref_counts)
1617    }
1618
1619    pub fn spawn<S, F, U>(&mut self, future: S, callback: F) -> EntityTask<U>
1620    where
1621        S: 'static + Future,
1622        F: 'static + FnOnce(&mut T, S::Output, &mut ModelContext<T>) -> U,
1623        U: 'static,
1624    {
1625        let handle = self.handle();
1626        let weak_handle = handle.downgrade();
1627        let task = self
1628            .app
1629            .spawn::<S, U>(Spawner::Model(handle.into()), future);
1630
1631        self.app.future_handlers.borrow_mut().insert(
1632            task.id,
1633            Box::new(move |output, ctx| {
1634                weak_handle.upgrade(ctx.as_ref()).map(|handle| {
1635                    let output = *output.downcast().unwrap();
1636                    handle.update(ctx, |model, ctx| {
1637                        Box::new(callback(model, output, ctx)) as Box<dyn Any>
1638                    })
1639                })
1640            }),
1641        );
1642
1643        task
1644    }
1645
1646    pub fn spawn_stream<S, F, G, U>(
1647        &mut self,
1648        stream: S,
1649        mut item_callback: F,
1650        done_callback: G,
1651    ) -> EntityTask<U>
1652    where
1653        S: 'static + Stream + Unpin,
1654        F: 'static + FnMut(&mut T, S::Item, &mut ModelContext<T>),
1655        G: 'static + FnOnce(&mut T, &mut ModelContext<T>) -> U,
1656        U: 'static + Any,
1657    {
1658        let handle = self.handle();
1659        let weak_handle = handle.downgrade();
1660        let task = self.app.spawn_stream(Spawner::Model(handle.into()), stream);
1661
1662        self.app.stream_handlers.borrow_mut().insert(
1663            task.id,
1664            StreamHandler {
1665                item_callback: {
1666                    let weak_handle = weak_handle.clone();
1667                    Box::new(move |output, app| {
1668                        if let Some(handle) = weak_handle.upgrade(app.as_ref()) {
1669                            let output = *output.downcast().unwrap();
1670                            handle.update(app, |model, ctx| {
1671                                item_callback(model, output, ctx);
1672                                ctx.halt_stream
1673                            })
1674                        } else {
1675                            true
1676                        }
1677                    })
1678                },
1679                done_callback: Box::new(move |app| {
1680                    weak_handle.upgrade(app.as_ref()).map(|handle| {
1681                        handle.update(app, |model, ctx| Box::new(done_callback(model, ctx)))
1682                            as Box<dyn Any>
1683                    })
1684                }),
1685            },
1686        );
1687
1688        task
1689    }
1690}
1691
1692impl<M> AsRef<AppContext> for ModelContext<'_, M> {
1693    fn as_ref(&self) -> &AppContext {
1694        &self.app.ctx
1695    }
1696}
1697
1698impl<M> AsMut<MutableAppContext> for ModelContext<'_, M> {
1699    fn as_mut(&mut self) -> &mut MutableAppContext {
1700        self.app
1701    }
1702}
1703
1704impl<M> ReadModel for ModelContext<'_, M> {
1705    fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T {
1706        self.app.read_model(handle)
1707    }
1708}
1709
1710impl<M> UpdateModel for ModelContext<'_, M> {
1711    fn update_model<T, F, S>(&mut self, handle: &ModelHandle<T>, update: F) -> S
1712    where
1713        T: Entity,
1714        F: FnOnce(&mut T, &mut ModelContext<T>) -> S,
1715    {
1716        self.app.update_model(handle, update)
1717    }
1718}
1719
1720pub struct ViewContext<'a, T: ?Sized> {
1721    app: &'a mut MutableAppContext,
1722    window_id: usize,
1723    view_id: usize,
1724    view_type: PhantomData<T>,
1725    halt_action_dispatch: bool,
1726    halt_stream: bool,
1727}
1728
1729impl<'a, T: View> ViewContext<'a, T> {
1730    fn new(app: &'a mut MutableAppContext, window_id: usize, view_id: usize) -> Self {
1731        Self {
1732            app,
1733            window_id,
1734            view_id,
1735            view_type: PhantomData,
1736            halt_action_dispatch: true,
1737            halt_stream: false,
1738        }
1739    }
1740
1741    pub fn handle(&self) -> ViewHandle<T> {
1742        ViewHandle::new(self.window_id, self.view_id, &self.app.ctx.ref_counts)
1743    }
1744
1745    pub fn window_id(&self) -> usize {
1746        self.window_id
1747    }
1748
1749    pub fn foreground(&self) -> &Rc<executor::Foreground> {
1750        self.app.foreground_executor()
1751    }
1752
1753    pub fn background_executor(&self) -> &Arc<executor::Background> {
1754        &self.app.ctx.background
1755    }
1756
1757    pub fn debug_elements(&self) -> crate::json::Value {
1758        self.app.debug_elements(self.window_id).unwrap()
1759    }
1760
1761    pub fn focus<S>(&mut self, handle: S)
1762    where
1763        S: Into<AnyViewHandle>,
1764    {
1765        let handle = handle.into();
1766        self.app.pending_effects.push_back(Effect::Focus {
1767            window_id: handle.window_id,
1768            view_id: handle.view_id,
1769        });
1770    }
1771
1772    pub fn focus_self(&mut self) {
1773        self.app.pending_effects.push_back(Effect::Focus {
1774            window_id: self.window_id,
1775            view_id: self.view_id,
1776        });
1777    }
1778
1779    pub fn add_model<S, F>(&mut self, build_model: F) -> ModelHandle<S>
1780    where
1781        S: Entity,
1782        F: FnOnce(&mut ModelContext<S>) -> S,
1783    {
1784        self.app.add_model(build_model)
1785    }
1786
1787    pub fn add_view<S, F>(&mut self, build_view: F) -> ViewHandle<S>
1788    where
1789        S: View,
1790        F: FnOnce(&mut ViewContext<S>) -> S,
1791    {
1792        self.app.add_view(self.window_id, build_view)
1793    }
1794
1795    pub fn add_option_view<S, F>(&mut self, build_view: F) -> Option<ViewHandle<S>>
1796    where
1797        S: View,
1798        F: FnOnce(&mut ViewContext<S>) -> Option<S>,
1799    {
1800        self.app.add_option_view(self.window_id, build_view)
1801    }
1802
1803    pub fn subscribe_to_model<E, F>(&mut self, handle: &ModelHandle<E>, mut callback: F)
1804    where
1805        E: Entity,
1806        E::Event: 'static,
1807        F: 'static + FnMut(&mut T, ModelHandle<E>, &E::Event, &mut ViewContext<T>),
1808    {
1809        let emitter_handle = handle.downgrade();
1810        self.app
1811            .subscriptions
1812            .entry(handle.id())
1813            .or_default()
1814            .push(Subscription::FromView {
1815                window_id: self.window_id,
1816                view_id: self.view_id,
1817                callback: Box::new(move |view, payload, app, window_id, view_id| {
1818                    if let Some(emitter_handle) = emitter_handle.upgrade(app.as_ref()) {
1819                        let model = view.downcast_mut().expect("downcast is type safe");
1820                        let payload = payload.downcast_ref().expect("downcast is type safe");
1821                        let mut ctx = ViewContext::new(app, window_id, view_id);
1822                        callback(model, emitter_handle, payload, &mut ctx);
1823                    }
1824                }),
1825            });
1826    }
1827
1828    pub fn subscribe_to_view<V, F>(&mut self, handle: &ViewHandle<V>, mut callback: F)
1829    where
1830        V: View,
1831        V::Event: 'static,
1832        F: 'static + FnMut(&mut T, ViewHandle<V>, &V::Event, &mut ViewContext<T>),
1833    {
1834        let emitter_handle = handle.downgrade();
1835
1836        self.app
1837            .subscriptions
1838            .entry(handle.id())
1839            .or_default()
1840            .push(Subscription::FromView {
1841                window_id: self.window_id,
1842                view_id: self.view_id,
1843                callback: Box::new(move |view, payload, app, window_id, view_id| {
1844                    if let Some(emitter_handle) = emitter_handle.upgrade(&app) {
1845                        let model = view.downcast_mut().expect("downcast is type safe");
1846                        let payload = payload.downcast_ref().expect("downcast is type safe");
1847                        let mut ctx = ViewContext::new(app, window_id, view_id);
1848                        callback(model, emitter_handle, payload, &mut ctx);
1849                    }
1850                }),
1851            });
1852    }
1853
1854    pub fn emit(&mut self, payload: T::Event) {
1855        self.app.pending_effects.push_back(Effect::Event {
1856            entity_id: self.view_id,
1857            payload: Box::new(payload),
1858        });
1859    }
1860
1861    pub fn observe_model<S, F>(&mut self, handle: &ModelHandle<S>, mut callback: F)
1862    where
1863        S: Entity,
1864        F: 'static + FnMut(&mut T, ModelHandle<S>, &mut ViewContext<T>),
1865    {
1866        self.app
1867            .model_observations
1868            .entry(handle.id())
1869            .or_default()
1870            .push(ModelObservation::FromView {
1871                window_id: self.window_id,
1872                view_id: self.view_id,
1873                callback: Box::new(move |view, observed_id, app, window_id, view_id| {
1874                    let view = view.downcast_mut().expect("downcast is type safe");
1875                    let observed = ModelHandle::new(observed_id, &app.ctx.ref_counts);
1876                    let mut ctx = ViewContext::new(app, window_id, view_id);
1877                    callback(view, observed, &mut ctx);
1878                }),
1879            });
1880    }
1881
1882    pub fn observe_view<S, F>(&mut self, handle: &ViewHandle<S>, mut callback: F)
1883    where
1884        S: View,
1885        F: 'static + FnMut(&mut T, ViewHandle<S>, &mut ViewContext<T>),
1886    {
1887        self.app
1888            .view_observations
1889            .entry(handle.id())
1890            .or_default()
1891            .push(ViewObservation {
1892                window_id: self.window_id,
1893                view_id: self.view_id,
1894                callback: Box::new(
1895                    move |view,
1896                          observed_view_id,
1897                          observed_window_id,
1898                          app,
1899                          observing_window_id,
1900                          observing_view_id| {
1901                        let view = view.downcast_mut().expect("downcast is type safe");
1902                        let observed_handle = ViewHandle::new(
1903                            observed_view_id,
1904                            observed_window_id,
1905                            &app.ctx.ref_counts,
1906                        );
1907                        let mut ctx = ViewContext::new(app, observing_window_id, observing_view_id);
1908                        callback(view, observed_handle, &mut ctx);
1909                    },
1910                ),
1911            });
1912    }
1913
1914    pub fn notify(&mut self) {
1915        self.app.notify_view(self.window_id, self.view_id);
1916    }
1917
1918    pub fn propagate_action(&mut self) {
1919        self.halt_action_dispatch = false;
1920    }
1921
1922    pub fn halt_stream(&mut self) {
1923        self.halt_stream = true;
1924    }
1925
1926    pub fn spawn<S, F, U>(&mut self, future: S, callback: F) -> EntityTask<U>
1927    where
1928        S: 'static + Future,
1929        F: 'static + FnOnce(&mut T, S::Output, &mut ViewContext<T>) -> U,
1930        U: 'static,
1931    {
1932        let handle = self.handle();
1933        let weak_handle = handle.downgrade();
1934        let task = self.app.spawn(Spawner::View(handle.into()), future);
1935
1936        self.app.future_handlers.borrow_mut().insert(
1937            task.id,
1938            Box::new(move |output, app| {
1939                weak_handle.upgrade(app.as_ref()).map(|handle| {
1940                    let output = *output.downcast().unwrap();
1941                    handle.update(app, |view, ctx| {
1942                        Box::new(callback(view, output, ctx)) as Box<dyn Any>
1943                    })
1944                })
1945            }),
1946        );
1947
1948        task
1949    }
1950
1951    pub fn spawn_stream<S, F, G, U>(
1952        &mut self,
1953        stream: S,
1954        mut item_callback: F,
1955        done_callback: G,
1956    ) -> EntityTask<U>
1957    where
1958        S: 'static + Stream + Unpin,
1959        F: 'static + FnMut(&mut T, S::Item, &mut ViewContext<T>),
1960        G: 'static + FnOnce(&mut T, &mut ViewContext<T>) -> U,
1961        U: 'static + Any,
1962    {
1963        let handle = self.handle();
1964        let weak_handle = handle.downgrade();
1965        let task = self.app.spawn_stream(Spawner::View(handle.into()), stream);
1966        self.app.stream_handlers.borrow_mut().insert(
1967            task.id,
1968            StreamHandler {
1969                item_callback: {
1970                    let weak_handle = weak_handle.clone();
1971                    Box::new(move |output, ctx| {
1972                        if let Some(handle) = weak_handle.upgrade(ctx.as_ref()) {
1973                            let output = *output.downcast().unwrap();
1974                            handle.update(ctx, |view, ctx| {
1975                                item_callback(view, output, ctx);
1976                                ctx.halt_stream
1977                            })
1978                        } else {
1979                            true
1980                        }
1981                    })
1982                },
1983                done_callback: Box::new(move |ctx| {
1984                    weak_handle.upgrade(ctx.as_ref()).map(|handle| {
1985                        handle.update(ctx, |view, ctx| {
1986                            Box::new(done_callback(view, ctx)) as Box<dyn Any>
1987                        })
1988                    })
1989                }),
1990            },
1991        );
1992        task
1993    }
1994}
1995
1996impl AsRef<AppContext> for &AppContext {
1997    fn as_ref(&self) -> &AppContext {
1998        self
1999    }
2000}
2001
2002impl<M> AsRef<AppContext> for ViewContext<'_, M> {
2003    fn as_ref(&self) -> &AppContext {
2004        &self.app.ctx
2005    }
2006}
2007
2008impl<M> AsMut<MutableAppContext> for ViewContext<'_, M> {
2009    fn as_mut(&mut self) -> &mut MutableAppContext {
2010        self.app
2011    }
2012}
2013
2014impl<V> ReadModel for ViewContext<'_, V> {
2015    fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T {
2016        self.app.read_model(handle)
2017    }
2018}
2019
2020impl<V: View> UpdateModel for ViewContext<'_, V> {
2021    fn update_model<T, F, S>(&mut self, handle: &ModelHandle<T>, update: F) -> S
2022    where
2023        T: Entity,
2024        F: FnOnce(&mut T, &mut ModelContext<T>) -> S,
2025    {
2026        self.app.update_model(handle, update)
2027    }
2028}
2029
2030impl<V: View> ReadView for ViewContext<'_, V> {
2031    fn read_view<T: View>(&self, handle: &ViewHandle<T>) -> &T {
2032        self.app.read_view(handle)
2033    }
2034}
2035
2036impl<V: View> UpdateView for ViewContext<'_, V> {
2037    fn update_view<T, F, S>(&mut self, handle: &ViewHandle<T>, update: F) -> S
2038    where
2039        T: View,
2040        F: FnOnce(&mut T, &mut ViewContext<T>) -> S,
2041    {
2042        self.app.update_view(handle, update)
2043    }
2044}
2045
2046pub trait Handle<T> {
2047    fn id(&self) -> usize;
2048    fn location(&self) -> EntityLocation;
2049}
2050
2051#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash)]
2052pub enum EntityLocation {
2053    Model(usize),
2054    View(usize, usize),
2055}
2056
2057pub struct ModelHandle<T> {
2058    model_id: usize,
2059    model_type: PhantomData<T>,
2060    ref_counts: Weak<Mutex<RefCounts>>,
2061}
2062
2063impl<T: Entity> ModelHandle<T> {
2064    fn new(model_id: usize, ref_counts: &Arc<Mutex<RefCounts>>) -> Self {
2065        ref_counts.lock().inc_entity(model_id);
2066        Self {
2067            model_id,
2068            model_type: PhantomData,
2069            ref_counts: Arc::downgrade(ref_counts),
2070        }
2071    }
2072
2073    fn downgrade(&self) -> WeakModelHandle<T> {
2074        WeakModelHandle::new(self.model_id)
2075    }
2076
2077    pub fn id(&self) -> usize {
2078        self.model_id
2079    }
2080
2081    pub fn read<'a, A: ReadModel>(&self, app: &'a A) -> &'a T {
2082        app.read_model(self)
2083    }
2084
2085    pub fn update<A, F, S>(&self, app: &mut A, update: F) -> S
2086    where
2087        A: UpdateModel,
2088        F: FnOnce(&mut T, &mut ModelContext<T>) -> S,
2089    {
2090        app.update_model(self, update)
2091    }
2092
2093    pub fn condition(
2094        &self,
2095        ctx: &TestAppContext,
2096        predicate: impl FnMut(&T, &AppContext) -> bool,
2097    ) -> impl Future<Output = ()> {
2098        self.condition_with_duration(Duration::from_millis(100), ctx, predicate)
2099    }
2100
2101    pub fn condition_with_duration(
2102        &self,
2103        duration: Duration,
2104        ctx: &TestAppContext,
2105        mut predicate: impl FnMut(&T, &AppContext) -> bool,
2106    ) -> impl Future<Output = ()> {
2107        let mut ctx = ctx.0.borrow_mut();
2108        let tx = ctx
2109            .async_observations
2110            .entry(self.id())
2111            .or_insert_with(|| postage::broadcast::channel(128).0);
2112        let mut rx = tx.subscribe();
2113        let ctx = ctx.weak_self.as_ref().unwrap().upgrade().unwrap();
2114        let handle = self.downgrade();
2115
2116        async move {
2117            timeout(duration, async move {
2118                loop {
2119                    {
2120                        let ctx = ctx.borrow();
2121                        let ctx = ctx.as_ref();
2122                        if predicate(
2123                            handle
2124                                .upgrade(ctx)
2125                                .expect("model dropped with pending condition")
2126                                .read(ctx),
2127                            ctx,
2128                        ) {
2129                            break;
2130                        }
2131                    }
2132
2133                    rx.recv()
2134                        .await
2135                        .expect("model dropped with pending condition");
2136                }
2137            })
2138            .await
2139            .expect("condition timed out");
2140        }
2141    }
2142}
2143
2144impl<T> Clone for ModelHandle<T> {
2145    fn clone(&self) -> Self {
2146        if let Some(ref_counts) = self.ref_counts.upgrade() {
2147            ref_counts.lock().inc_entity(self.model_id);
2148        }
2149
2150        Self {
2151            model_id: self.model_id,
2152            model_type: PhantomData,
2153            ref_counts: self.ref_counts.clone(),
2154        }
2155    }
2156}
2157
2158impl<T> PartialEq for ModelHandle<T> {
2159    fn eq(&self, other: &Self) -> bool {
2160        self.model_id == other.model_id
2161    }
2162}
2163
2164impl<T> Eq for ModelHandle<T> {}
2165
2166impl<T> Hash for ModelHandle<T> {
2167    fn hash<H: Hasher>(&self, state: &mut H) {
2168        self.model_id.hash(state);
2169    }
2170}
2171
2172impl<T> std::borrow::Borrow<usize> for ModelHandle<T> {
2173    fn borrow(&self) -> &usize {
2174        &self.model_id
2175    }
2176}
2177
2178impl<T> Debug for ModelHandle<T> {
2179    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2180        f.debug_tuple(&format!("ModelHandle<{}>", type_name::<T>()))
2181            .field(&self.model_id)
2182            .finish()
2183    }
2184}
2185
2186unsafe impl<T> Send for ModelHandle<T> {}
2187unsafe impl<T> Sync for ModelHandle<T> {}
2188
2189impl<T> Drop for ModelHandle<T> {
2190    fn drop(&mut self) {
2191        if let Some(ref_counts) = self.ref_counts.upgrade() {
2192            ref_counts.lock().dec_model(self.model_id);
2193        }
2194    }
2195}
2196
2197impl<T> Handle<T> for ModelHandle<T> {
2198    fn id(&self) -> usize {
2199        self.model_id
2200    }
2201
2202    fn location(&self) -> EntityLocation {
2203        EntityLocation::Model(self.model_id)
2204    }
2205}
2206
2207pub struct WeakModelHandle<T> {
2208    model_id: usize,
2209    model_type: PhantomData<T>,
2210}
2211
2212impl<T: Entity> WeakModelHandle<T> {
2213    fn new(model_id: usize) -> Self {
2214        Self {
2215            model_id,
2216            model_type: PhantomData,
2217        }
2218    }
2219
2220    pub fn upgrade(&self, app: &AppContext) -> Option<ModelHandle<T>> {
2221        if app.models.contains_key(&self.model_id) {
2222            Some(ModelHandle::new(self.model_id, &app.ref_counts))
2223        } else {
2224            None
2225        }
2226    }
2227}
2228
2229impl<T> Clone for WeakModelHandle<T> {
2230    fn clone(&self) -> Self {
2231        Self {
2232            model_id: self.model_id,
2233            model_type: PhantomData,
2234        }
2235    }
2236}
2237
2238pub struct AnyModelHandle {
2239    model_id: usize,
2240    ref_counts: Weak<Mutex<RefCounts>>,
2241}
2242
2243impl<T: Entity> From<ModelHandle<T>> for AnyModelHandle {
2244    fn from(handle: ModelHandle<T>) -> Self {
2245        if let Some(ref_counts) = handle.ref_counts.upgrade() {
2246            ref_counts.lock().inc_entity(handle.model_id);
2247        }
2248        Self {
2249            model_id: handle.model_id,
2250            ref_counts: handle.ref_counts.clone(),
2251        }
2252    }
2253}
2254
2255impl Drop for AnyModelHandle {
2256    fn drop(&mut self) {
2257        if let Some(ref_counts) = self.ref_counts.upgrade() {
2258            ref_counts.lock().dec_model(self.model_id);
2259        }
2260    }
2261}
2262
2263pub struct ViewHandle<T> {
2264    window_id: usize,
2265    view_id: usize,
2266    view_type: PhantomData<T>,
2267    ref_counts: Weak<Mutex<RefCounts>>,
2268}
2269
2270impl<T: View> ViewHandle<T> {
2271    fn new(window_id: usize, view_id: usize, ref_counts: &Arc<Mutex<RefCounts>>) -> Self {
2272        ref_counts.lock().inc_entity(view_id);
2273        Self {
2274            window_id,
2275            view_id,
2276            view_type: PhantomData,
2277            ref_counts: Arc::downgrade(ref_counts),
2278        }
2279    }
2280
2281    pub fn downgrade(&self) -> WeakViewHandle<T> {
2282        WeakViewHandle::new(self.window_id, self.view_id)
2283    }
2284
2285    pub fn window_id(&self) -> usize {
2286        self.window_id
2287    }
2288
2289    pub fn id(&self) -> usize {
2290        self.view_id
2291    }
2292
2293    pub fn read<'a, A: ReadView>(&self, app: &'a A) -> &'a T {
2294        app.read_view(self)
2295    }
2296
2297    pub fn update<A, F, S>(&self, app: &mut A, update: F) -> S
2298    where
2299        A: UpdateView,
2300        F: FnOnce(&mut T, &mut ViewContext<T>) -> S,
2301    {
2302        app.update_view(self, update)
2303    }
2304
2305    pub fn is_focused(&self, app: &AppContext) -> bool {
2306        app.focused_view_id(self.window_id)
2307            .map_or(false, |focused_id| focused_id == self.view_id)
2308    }
2309
2310    pub fn condition(
2311        &self,
2312        ctx: &TestAppContext,
2313        mut predicate: impl 'static + FnMut(&T, &AppContext) -> bool,
2314    ) -> impl 'static + Future<Output = ()> {
2315        let mut ctx = ctx.0.borrow_mut();
2316        let tx = ctx
2317            .async_observations
2318            .entry(self.id())
2319            .or_insert_with(|| postage::broadcast::channel(128).0);
2320        let mut rx = tx.subscribe();
2321        let ctx = ctx.weak_self.as_ref().unwrap().upgrade().unwrap();
2322        let handle = self.downgrade();
2323
2324        async move {
2325            timeout(Duration::from_millis(200), async move {
2326                loop {
2327                    {
2328                        let ctx = ctx.borrow();
2329                        let ctx = ctx.as_ref();
2330                        if predicate(
2331                            handle
2332                                .upgrade(ctx)
2333                                .expect("model dropped with pending condition")
2334                                .read(ctx),
2335                            ctx,
2336                        ) {
2337                            break;
2338                        }
2339                    }
2340
2341                    rx.recv()
2342                        .await
2343                        .expect("model dropped with pending condition");
2344                }
2345            })
2346            .await
2347            .expect("condition timed out");
2348        }
2349    }
2350}
2351
2352impl<T> Clone for ViewHandle<T> {
2353    fn clone(&self) -> Self {
2354        if let Some(ref_counts) = self.ref_counts.upgrade() {
2355            ref_counts.lock().inc_entity(self.view_id);
2356        }
2357
2358        Self {
2359            window_id: self.window_id,
2360            view_id: self.view_id,
2361            view_type: PhantomData,
2362            ref_counts: self.ref_counts.clone(),
2363        }
2364    }
2365}
2366
2367impl<T> PartialEq for ViewHandle<T> {
2368    fn eq(&self, other: &Self) -> bool {
2369        self.window_id == other.window_id && self.view_id == other.view_id
2370    }
2371}
2372
2373impl<T> Eq for ViewHandle<T> {}
2374
2375impl<T> Debug for ViewHandle<T> {
2376    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2377        f.debug_struct(&format!("ViewHandle<{}>", type_name::<T>()))
2378            .field("window_id", &self.window_id)
2379            .field("view_id", &self.view_id)
2380            .finish()
2381    }
2382}
2383
2384impl<T> Drop for ViewHandle<T> {
2385    fn drop(&mut self) {
2386        if let Some(ref_counts) = self.ref_counts.upgrade() {
2387            ref_counts.lock().dec_view(self.window_id, self.view_id);
2388        }
2389    }
2390}
2391
2392impl<T> Handle<T> for ViewHandle<T> {
2393    fn id(&self) -> usize {
2394        self.view_id
2395    }
2396
2397    fn location(&self) -> EntityLocation {
2398        EntityLocation::View(self.window_id, self.view_id)
2399    }
2400}
2401
2402#[derive(Clone)]
2403pub struct AnyViewHandle {
2404    window_id: usize,
2405    view_id: usize,
2406    view_type: TypeId,
2407    ref_counts: Weak<Mutex<RefCounts>>,
2408}
2409
2410impl AnyViewHandle {
2411    pub fn id(&self) -> usize {
2412        self.view_id
2413    }
2414
2415    pub fn is<T: 'static>(&self) -> bool {
2416        TypeId::of::<T>() == self.view_type
2417    }
2418
2419    pub fn downcast<T: View>(self) -> Option<ViewHandle<T>> {
2420        if self.is::<T>() {
2421            if let Some(ref_counts) = self.ref_counts.upgrade() {
2422                return Some(ViewHandle::new(self.window_id, self.view_id, &ref_counts));
2423            }
2424        }
2425        None
2426    }
2427}
2428
2429impl<T: View> From<&ViewHandle<T>> for AnyViewHandle {
2430    fn from(handle: &ViewHandle<T>) -> Self {
2431        if let Some(ref_counts) = handle.ref_counts.upgrade() {
2432            ref_counts.lock().inc_entity(handle.view_id);
2433        }
2434        AnyViewHandle {
2435            window_id: handle.window_id,
2436            view_id: handle.view_id,
2437            view_type: TypeId::of::<T>(),
2438            ref_counts: handle.ref_counts.clone(),
2439        }
2440    }
2441}
2442
2443impl<T: View> From<ViewHandle<T>> for AnyViewHandle {
2444    fn from(handle: ViewHandle<T>) -> Self {
2445        (&handle).into()
2446    }
2447}
2448
2449impl Drop for AnyViewHandle {
2450    fn drop(&mut self) {
2451        if let Some(ref_counts) = self.ref_counts.upgrade() {
2452            ref_counts.lock().dec_view(self.window_id, self.view_id);
2453        }
2454    }
2455}
2456
2457pub struct WeakViewHandle<T> {
2458    window_id: usize,
2459    view_id: usize,
2460    view_type: PhantomData<T>,
2461}
2462
2463impl<T: View> WeakViewHandle<T> {
2464    fn new(window_id: usize, view_id: usize) -> Self {
2465        Self {
2466            window_id,
2467            view_id,
2468            view_type: PhantomData,
2469        }
2470    }
2471
2472    pub fn upgrade(&self, ctx: impl AsRef<AppContext>) -> Option<ViewHandle<T>> {
2473        let ctx = ctx.as_ref();
2474        if ctx.views.get(&(self.window_id, self.view_id)).is_some() {
2475            Some(ViewHandle::new(
2476                self.window_id,
2477                self.view_id,
2478                &ctx.ref_counts,
2479            ))
2480        } else {
2481            None
2482        }
2483    }
2484}
2485
2486impl<T> Clone for WeakViewHandle<T> {
2487    fn clone(&self) -> Self {
2488        Self {
2489            window_id: self.window_id,
2490            view_id: self.view_id,
2491            view_type: PhantomData,
2492        }
2493    }
2494}
2495
2496pub struct ValueHandle<T> {
2497    value_type: PhantomData<T>,
2498    tag_type_id: TypeId,
2499    id: usize,
2500    ref_counts: Weak<Mutex<RefCounts>>,
2501}
2502
2503impl<T: 'static> ValueHandle<T> {
2504    fn new(tag_type_id: TypeId, id: usize, ref_counts: &Arc<Mutex<RefCounts>>) -> Self {
2505        ref_counts.lock().inc_value(tag_type_id, id);
2506        Self {
2507            value_type: PhantomData,
2508            tag_type_id,
2509            id,
2510            ref_counts: Arc::downgrade(ref_counts),
2511        }
2512    }
2513
2514    pub fn read<R>(&self, ctx: &AppContext, f: impl FnOnce(&T) -> R) -> R {
2515        f(ctx
2516            .values
2517            .read()
2518            .get(&(self.tag_type_id, self.id))
2519            .unwrap()
2520            .downcast_ref()
2521            .unwrap())
2522    }
2523
2524    pub fn update<R>(&self, ctx: &AppContext, f: impl FnOnce(&mut T) -> R) -> R {
2525        f(ctx
2526            .values
2527            .write()
2528            .get_mut(&(self.tag_type_id, self.id))
2529            .unwrap()
2530            .downcast_mut()
2531            .unwrap())
2532    }
2533}
2534
2535impl<T> Drop for ValueHandle<T> {
2536    fn drop(&mut self) {
2537        if let Some(ref_counts) = self.ref_counts.upgrade() {
2538            ref_counts.lock().dec_value(self.tag_type_id, self.id);
2539        }
2540    }
2541}
2542
2543#[derive(Default)]
2544struct RefCounts {
2545    entity_counts: HashMap<usize, usize>,
2546    value_counts: HashMap<(TypeId, usize), usize>,
2547    dropped_models: HashSet<usize>,
2548    dropped_views: HashSet<(usize, usize)>,
2549    dropped_values: HashSet<(TypeId, usize)>,
2550}
2551
2552impl RefCounts {
2553    fn inc_entity(&mut self, model_id: usize) {
2554        *self.entity_counts.entry(model_id).or_insert(0) += 1;
2555    }
2556
2557    fn inc_value(&mut self, tag_type_id: TypeId, id: usize) {
2558        *self.value_counts.entry((tag_type_id, id)).or_insert(0) += 1;
2559    }
2560
2561    fn dec_model(&mut self, model_id: usize) {
2562        let count = self.entity_counts.get_mut(&model_id).unwrap();
2563        *count -= 1;
2564        if *count == 0 {
2565            self.entity_counts.remove(&model_id);
2566            self.dropped_models.insert(model_id);
2567        }
2568    }
2569
2570    fn dec_view(&mut self, window_id: usize, view_id: usize) {
2571        let count = self.entity_counts.get_mut(&view_id).unwrap();
2572        *count -= 1;
2573        if *count == 0 {
2574            self.entity_counts.remove(&view_id);
2575            self.dropped_views.insert((window_id, view_id));
2576        }
2577    }
2578
2579    fn dec_value(&mut self, tag_type_id: TypeId, id: usize) {
2580        let key = (tag_type_id, id);
2581        let count = self.value_counts.get_mut(&key).unwrap();
2582        *count -= 1;
2583        if *count == 0 {
2584            self.value_counts.remove(&key);
2585            self.dropped_values.insert(key);
2586        }
2587    }
2588
2589    fn take_dropped(
2590        &mut self,
2591    ) -> (
2592        HashSet<usize>,
2593        HashSet<(usize, usize)>,
2594        HashSet<(TypeId, usize)>,
2595    ) {
2596        let mut dropped_models = HashSet::new();
2597        let mut dropped_views = HashSet::new();
2598        let mut dropped_values = HashSet::new();
2599        std::mem::swap(&mut self.dropped_models, &mut dropped_models);
2600        std::mem::swap(&mut self.dropped_views, &mut dropped_views);
2601        std::mem::swap(&mut self.dropped_values, &mut dropped_values);
2602        (dropped_models, dropped_views, dropped_values)
2603    }
2604}
2605
2606enum Subscription {
2607    FromModel {
2608        model_id: usize,
2609        callback: Box<dyn FnMut(&mut dyn Any, &dyn Any, &mut MutableAppContext, usize)>,
2610    },
2611    FromView {
2612        window_id: usize,
2613        view_id: usize,
2614        callback: Box<dyn FnMut(&mut dyn Any, &dyn Any, &mut MutableAppContext, usize, usize)>,
2615    },
2616}
2617
2618enum ModelObservation {
2619    FromModel {
2620        model_id: usize,
2621        callback: Box<dyn FnMut(&mut dyn Any, usize, &mut MutableAppContext, usize)>,
2622    },
2623    FromView {
2624        window_id: usize,
2625        view_id: usize,
2626        callback: Box<dyn FnMut(&mut dyn Any, usize, &mut MutableAppContext, usize, usize)>,
2627    },
2628}
2629
2630struct ViewObservation {
2631    window_id: usize,
2632    view_id: usize,
2633    callback: Box<dyn FnMut(&mut dyn Any, usize, usize, &mut MutableAppContext, usize, usize)>,
2634}
2635
2636type FutureHandler = Box<dyn FnOnce(Box<dyn Any>, &mut MutableAppContext) -> Option<Box<dyn Any>>>;
2637
2638struct StreamHandler {
2639    item_callback: Box<dyn FnMut(Box<dyn Any>, &mut MutableAppContext) -> bool>,
2640    done_callback: Box<dyn FnOnce(&mut MutableAppContext) -> Option<Box<dyn Any>>>,
2641}
2642
2643#[must_use]
2644pub struct EntityTask<T> {
2645    id: usize,
2646    task: Option<executor::Task<Option<T>>>,
2647    _spawner: Spawner, // Keeps the spawning entity alive for as long as the task exists
2648    handler_map: TaskHandlerMap,
2649}
2650
2651pub enum Spawner {
2652    Model(AnyModelHandle),
2653    View(AnyViewHandle),
2654}
2655
2656enum TaskHandlerMap {
2657    Detached,
2658    Future(Rc<RefCell<HashMap<usize, FutureHandler>>>),
2659    Stream(Rc<RefCell<HashMap<usize, StreamHandler>>>),
2660}
2661
2662impl<T> EntityTask<T> {
2663    fn new(
2664        id: usize,
2665        task: executor::Task<Option<T>>,
2666        spawner: Spawner,
2667        handler_map: TaskHandlerMap,
2668    ) -> Self {
2669        Self {
2670            id,
2671            task: Some(task),
2672            _spawner: spawner,
2673            handler_map,
2674        }
2675    }
2676
2677    pub fn detach(mut self) {
2678        self.handler_map = TaskHandlerMap::Detached;
2679        self.task.take().unwrap().detach();
2680    }
2681
2682    pub async fn cancel(mut self) -> Option<T> {
2683        let task = self.task.take().unwrap();
2684        task.cancel().await.unwrap()
2685    }
2686}
2687
2688impl<T> Future for EntityTask<T> {
2689    type Output = T;
2690
2691    fn poll(
2692        self: std::pin::Pin<&mut Self>,
2693        ctx: &mut std::task::Context<'_>,
2694    ) -> std::task::Poll<Self::Output> {
2695        let task = unsafe { self.map_unchecked_mut(|task| task.task.as_mut().unwrap()) };
2696        task.poll(ctx).map(|output| output.unwrap())
2697    }
2698}
2699
2700impl<T> Drop for EntityTask<T> {
2701    fn drop(self: &mut Self) {
2702        match &self.handler_map {
2703            TaskHandlerMap::Detached => {
2704                return;
2705            }
2706            TaskHandlerMap::Future(map) => {
2707                map.borrow_mut().remove(&self.id);
2708            }
2709            TaskHandlerMap::Stream(map) => {
2710                map.borrow_mut().remove(&self.id);
2711            }
2712        }
2713    }
2714}
2715
2716#[cfg(test)]
2717mod tests {
2718    use super::*;
2719    use crate::elements::*;
2720    use smol::future::poll_once;
2721
2722    #[test]
2723    fn test_model_handles() {
2724        struct Model {
2725            other: Option<ModelHandle<Model>>,
2726            events: Vec<String>,
2727        }
2728
2729        impl Entity for Model {
2730            type Event = usize;
2731        }
2732
2733        impl Model {
2734            fn new(other: Option<ModelHandle<Self>>, ctx: &mut ModelContext<Self>) -> Self {
2735                if let Some(other) = other.as_ref() {
2736                    ctx.observe(other, |me, _, _| {
2737                        me.events.push("notified".into());
2738                    });
2739                    ctx.subscribe(other, |me, event, _| {
2740                        me.events.push(format!("observed event {}", event));
2741                    });
2742                }
2743
2744                Self {
2745                    other,
2746                    events: Vec::new(),
2747                }
2748            }
2749        }
2750
2751        App::test((), |app| {
2752            let handle_1 = app.add_model(|ctx| Model::new(None, ctx));
2753            let handle_2 = app.add_model(|ctx| Model::new(Some(handle_1.clone()), ctx));
2754            assert_eq!(app.ctx.models.len(), 2);
2755
2756            handle_1.update(app, |model, ctx| {
2757                model.events.push("updated".into());
2758                ctx.emit(1);
2759                ctx.notify();
2760                ctx.emit(2);
2761            });
2762            assert_eq!(handle_1.read(app).events, vec!["updated".to_string()]);
2763            assert_eq!(
2764                handle_2.read(app).events,
2765                vec![
2766                    "observed event 1".to_string(),
2767                    "notified".to_string(),
2768                    "observed event 2".to_string(),
2769                ]
2770            );
2771
2772            handle_2.update(app, |model, _| {
2773                drop(handle_1);
2774                model.other.take();
2775            });
2776
2777            assert_eq!(app.ctx.models.len(), 1);
2778            assert!(app.subscriptions.is_empty());
2779            assert!(app.model_observations.is_empty());
2780        });
2781    }
2782
2783    #[test]
2784    fn test_subscribe_and_emit_from_model() {
2785        #[derive(Default)]
2786        struct Model {
2787            events: Vec<usize>,
2788        }
2789
2790        impl Entity for Model {
2791            type Event = usize;
2792        }
2793
2794        App::test((), |app| {
2795            let handle_1 = app.add_model(|_| Model::default());
2796            let handle_2 = app.add_model(|_| Model::default());
2797            let handle_2b = handle_2.clone();
2798
2799            handle_1.update(app, |_, c| {
2800                c.subscribe(&handle_2, move |model: &mut Model, event, c| {
2801                    model.events.push(*event);
2802
2803                    c.subscribe(&handle_2b, |model, event, _| {
2804                        model.events.push(*event * 2);
2805                    });
2806                });
2807            });
2808
2809            handle_2.update(app, |_, c| c.emit(7));
2810            assert_eq!(handle_1.read(app).events, vec![7]);
2811
2812            handle_2.update(app, |_, c| c.emit(5));
2813            assert_eq!(handle_1.read(app).events, vec![7, 10, 5]);
2814        })
2815    }
2816
2817    #[test]
2818    fn test_observe_and_notify_from_model() {
2819        #[derive(Default)]
2820        struct Model {
2821            count: usize,
2822            events: Vec<usize>,
2823        }
2824
2825        impl Entity for Model {
2826            type Event = ();
2827        }
2828
2829        App::test((), |app| {
2830            let handle_1 = app.add_model(|_| Model::default());
2831            let handle_2 = app.add_model(|_| Model::default());
2832            let handle_2b = handle_2.clone();
2833
2834            handle_1.update(app, |_, c| {
2835                c.observe(&handle_2, move |model, observed, c| {
2836                    model.events.push(observed.read(c).count);
2837                    c.observe(&handle_2b, |model, observed, c| {
2838                        model.events.push(observed.read(c).count * 2);
2839                    });
2840                });
2841            });
2842
2843            handle_2.update(app, |model, c| {
2844                model.count = 7;
2845                c.notify()
2846            });
2847            assert_eq!(handle_1.read(app).events, vec![7]);
2848
2849            handle_2.update(app, |model, c| {
2850                model.count = 5;
2851                c.notify()
2852            });
2853            assert_eq!(handle_1.read(app).events, vec![7, 10, 5])
2854        })
2855    }
2856
2857    #[test]
2858    fn test_spawn_from_model() {
2859        #[derive(Default)]
2860        struct Model {
2861            count: usize,
2862        }
2863
2864        impl Entity for Model {
2865            type Event = ();
2866        }
2867
2868        App::test_async((), |mut app| async move {
2869            let handle = app.add_model(|_| Model::default());
2870            handle
2871                .update(&mut app, |_, c| {
2872                    c.spawn(async { 7 }, |model, output, _| {
2873                        model.count = output;
2874                    })
2875                })
2876                .await;
2877            app.read(|ctx| assert_eq!(handle.read(ctx).count, 7));
2878
2879            handle
2880                .update(&mut app, |_, c| {
2881                    c.spawn(async { 14 }, |model, output, _| {
2882                        model.count = output;
2883                    })
2884                })
2885                .await;
2886            app.read(|ctx| assert_eq!(handle.read(ctx).count, 14));
2887        });
2888    }
2889
2890    #[test]
2891    fn test_spawn_stream_local_from_model() {
2892        #[derive(Default)]
2893        struct Model {
2894            events: Vec<Option<usize>>,
2895        }
2896
2897        impl Entity for Model {
2898            type Event = ();
2899        }
2900
2901        App::test_async((), |mut app| async move {
2902            let handle = app.add_model(|_| Model::default());
2903            handle
2904                .update(&mut app, |_, c| {
2905                    c.spawn_stream(
2906                        smol::stream::iter(vec![1, 2, 3]),
2907                        |model, output, _| {
2908                            model.events.push(Some(output));
2909                        },
2910                        |model, _| {
2911                            model.events.push(None);
2912                        },
2913                    )
2914                })
2915                .await;
2916            app.read(|ctx| assert_eq!(handle.read(ctx).events, [Some(1), Some(2), Some(3), None]));
2917        })
2918    }
2919
2920    #[test]
2921    fn test_view_handles() {
2922        struct View {
2923            other: Option<ViewHandle<View>>,
2924            events: Vec<String>,
2925        }
2926
2927        impl Entity for View {
2928            type Event = usize;
2929        }
2930
2931        impl super::View for View {
2932            fn render<'a>(&self, _: &AppContext) -> ElementBox {
2933                Empty::new().boxed()
2934            }
2935
2936            fn ui_name() -> &'static str {
2937                "View"
2938            }
2939        }
2940
2941        impl View {
2942            fn new(other: Option<ViewHandle<View>>, ctx: &mut ViewContext<Self>) -> Self {
2943                if let Some(other) = other.as_ref() {
2944                    ctx.subscribe_to_view(other, |me, _, event, _| {
2945                        me.events.push(format!("observed event {}", event));
2946                    });
2947                }
2948                Self {
2949                    other,
2950                    events: Vec::new(),
2951                }
2952            }
2953        }
2954
2955        App::test((), |app| {
2956            let (window_id, _) = app.add_window(|ctx| View::new(None, ctx));
2957            let handle_1 = app.add_view(window_id, |ctx| View::new(None, ctx));
2958            let handle_2 = app.add_view(window_id, |ctx| View::new(Some(handle_1.clone()), ctx));
2959            assert_eq!(app.ctx.views.len(), 3);
2960
2961            handle_1.update(app, |view, ctx| {
2962                view.events.push("updated".into());
2963                ctx.emit(1);
2964                ctx.emit(2);
2965            });
2966            assert_eq!(handle_1.read(app).events, vec!["updated".to_string()]);
2967            assert_eq!(
2968                handle_2.read(app).events,
2969                vec![
2970                    "observed event 1".to_string(),
2971                    "observed event 2".to_string(),
2972                ]
2973            );
2974
2975            handle_2.update(app, |view, _| {
2976                drop(handle_1);
2977                view.other.take();
2978            });
2979
2980            assert_eq!(app.ctx.views.len(), 2);
2981            assert!(app.subscriptions.is_empty());
2982            assert!(app.model_observations.is_empty());
2983        })
2984    }
2985
2986    #[test]
2987    fn test_subscribe_and_emit_from_view() {
2988        #[derive(Default)]
2989        struct View {
2990            events: Vec<usize>,
2991        }
2992
2993        impl Entity for View {
2994            type Event = usize;
2995        }
2996
2997        impl super::View for View {
2998            fn render<'a>(&self, _: &AppContext) -> ElementBox {
2999                Empty::new().boxed()
3000            }
3001
3002            fn ui_name() -> &'static str {
3003                "View"
3004            }
3005        }
3006
3007        struct Model;
3008
3009        impl Entity for Model {
3010            type Event = usize;
3011        }
3012
3013        App::test((), |app| {
3014            let (window_id, handle_1) = app.add_window(|_| View::default());
3015            let handle_2 = app.add_view(window_id, |_| View::default());
3016            let handle_2b = handle_2.clone();
3017            let handle_3 = app.add_model(|_| Model);
3018
3019            handle_1.update(app, |_, c| {
3020                c.subscribe_to_view(&handle_2, move |me, _, event, c| {
3021                    me.events.push(*event);
3022
3023                    c.subscribe_to_view(&handle_2b, |me, _, event, _| {
3024                        me.events.push(*event * 2);
3025                    });
3026                });
3027
3028                c.subscribe_to_model(&handle_3, |me, _, event, _| {
3029                    me.events.push(*event);
3030                })
3031            });
3032
3033            handle_2.update(app, |_, c| c.emit(7));
3034            assert_eq!(handle_1.read(app).events, vec![7]);
3035
3036            handle_2.update(app, |_, c| c.emit(5));
3037            assert_eq!(handle_1.read(app).events, vec![7, 10, 5]);
3038
3039            handle_3.update(app, |_, c| c.emit(9));
3040            assert_eq!(handle_1.read(app).events, vec![7, 10, 5, 9]);
3041        })
3042    }
3043
3044    #[test]
3045    fn test_dropping_subscribers() {
3046        struct View;
3047
3048        impl Entity for View {
3049            type Event = ();
3050        }
3051
3052        impl super::View for View {
3053            fn render<'a>(&self, _: &AppContext) -> ElementBox {
3054                Empty::new().boxed()
3055            }
3056
3057            fn ui_name() -> &'static str {
3058                "View"
3059            }
3060        }
3061
3062        struct Model;
3063
3064        impl Entity for Model {
3065            type Event = ();
3066        }
3067
3068        App::test((), |app| {
3069            let (window_id, _) = app.add_window(|_| View);
3070            let observing_view = app.add_view(window_id, |_| View);
3071            let emitting_view = app.add_view(window_id, |_| View);
3072            let observing_model = app.add_model(|_| Model);
3073            let observed_model = app.add_model(|_| Model);
3074
3075            observing_view.update(app, |_, ctx| {
3076                ctx.subscribe_to_view(&emitting_view, |_, _, _, _| {});
3077                ctx.subscribe_to_model(&observed_model, |_, _, _, _| {});
3078            });
3079            observing_model.update(app, |_, ctx| {
3080                ctx.subscribe(&observed_model, |_, _, _| {});
3081            });
3082
3083            app.update(|| {
3084                drop(observing_view);
3085                drop(observing_model);
3086            });
3087
3088            emitting_view.update(app, |_, ctx| ctx.emit(()));
3089            observed_model.update(app, |_, ctx| ctx.emit(()));
3090        })
3091    }
3092
3093    #[test]
3094    fn test_observe_and_notify_from_view() {
3095        #[derive(Default)]
3096        struct View {
3097            events: Vec<usize>,
3098        }
3099
3100        impl Entity for View {
3101            type Event = usize;
3102        }
3103
3104        impl super::View for View {
3105            fn render<'a>(&self, _: &AppContext) -> ElementBox {
3106                Empty::new().boxed()
3107            }
3108
3109            fn ui_name() -> &'static str {
3110                "View"
3111            }
3112        }
3113
3114        #[derive(Default)]
3115        struct Model {
3116            count: usize,
3117        }
3118
3119        impl Entity for Model {
3120            type Event = ();
3121        }
3122
3123        App::test((), |app| {
3124            let (_, view) = app.add_window(|_| View::default());
3125            let model = app.add_model(|_| Model::default());
3126
3127            view.update(app, |_, c| {
3128                c.observe_model(&model, |me, observed, c| {
3129                    me.events.push(observed.read(c).count)
3130                });
3131            });
3132
3133            model.update(app, |model, c| {
3134                model.count = 11;
3135                c.notify();
3136            });
3137            assert_eq!(view.read(app).events, vec![11]);
3138        })
3139    }
3140
3141    #[test]
3142    fn test_dropping_observers() {
3143        struct View;
3144
3145        impl Entity for View {
3146            type Event = ();
3147        }
3148
3149        impl super::View for View {
3150            fn render<'a>(&self, _: &AppContext) -> ElementBox {
3151                Empty::new().boxed()
3152            }
3153
3154            fn ui_name() -> &'static str {
3155                "View"
3156            }
3157        }
3158
3159        struct Model;
3160
3161        impl Entity for Model {
3162            type Event = ();
3163        }
3164
3165        App::test((), |app| {
3166            let (window_id, _) = app.add_window(|_| View);
3167            let observing_view = app.add_view(window_id, |_| View);
3168            let observing_model = app.add_model(|_| Model);
3169            let observed_model = app.add_model(|_| Model);
3170
3171            observing_view.update(app, |_, ctx| {
3172                ctx.observe_model(&observed_model, |_, _, _| {});
3173            });
3174            observing_model.update(app, |_, ctx| {
3175                ctx.observe(&observed_model, |_, _, _| {});
3176            });
3177
3178            app.update(|| {
3179                drop(observing_view);
3180                drop(observing_model);
3181            });
3182
3183            observed_model.update(app, |_, ctx| ctx.notify());
3184        })
3185    }
3186
3187    #[test]
3188    fn test_focus() {
3189        #[derive(Default)]
3190        struct View {
3191            events: Vec<String>,
3192        }
3193
3194        impl Entity for View {
3195            type Event = String;
3196        }
3197
3198        impl super::View for View {
3199            fn render<'a>(&self, _: &AppContext) -> ElementBox {
3200                Empty::new().boxed()
3201            }
3202
3203            fn ui_name() -> &'static str {
3204                "View"
3205            }
3206
3207            fn on_focus(&mut self, ctx: &mut ViewContext<Self>) {
3208                self.events.push("self focused".into());
3209                ctx.emit("focused".into());
3210            }
3211
3212            fn on_blur(&mut self, ctx: &mut ViewContext<Self>) {
3213                self.events.push("self blurred".into());
3214                ctx.emit("blurred".into());
3215            }
3216        }
3217
3218        App::test((), |app| {
3219            let (window_id, view_1) = app.add_window(|_| View::default());
3220            let view_2 = app.add_view(window_id, |_| View::default());
3221
3222            view_1.update(app, |_, ctx| {
3223                ctx.subscribe_to_view(&view_2, |view_1, _, event, _| {
3224                    view_1.events.push(format!("view 2 {}", event));
3225                });
3226                ctx.focus(&view_2);
3227            });
3228
3229            view_1.update(app, |_, ctx| {
3230                ctx.focus(&view_1);
3231            });
3232
3233            assert_eq!(
3234                view_1.read(app).events,
3235                [
3236                    "self focused".to_string(),
3237                    "self blurred".to_string(),
3238                    "view 2 focused".to_string(),
3239                    "self focused".to_string(),
3240                    "view 2 blurred".to_string(),
3241                ],
3242            );
3243        })
3244    }
3245
3246    #[test]
3247    fn test_spawn_from_view() {
3248        #[derive(Default)]
3249        struct View {
3250            count: usize,
3251        }
3252
3253        impl Entity for View {
3254            type Event = ();
3255        }
3256
3257        impl super::View for View {
3258            fn render<'a>(&self, _: &AppContext) -> ElementBox {
3259                Empty::new().boxed()
3260            }
3261
3262            fn ui_name() -> &'static str {
3263                "View"
3264            }
3265        }
3266
3267        App::test_async((), |mut app| async move {
3268            let handle = app.add_window(|_| View::default()).1;
3269            handle
3270                .update(&mut app, |_, c| {
3271                    c.spawn(async { 7 }, |me, output, _| {
3272                        me.count = output;
3273                    })
3274                })
3275                .await;
3276            app.read(|ctx| assert_eq!(handle.read(ctx).count, 7));
3277            handle
3278                .update(&mut app, |_, c| {
3279                    c.spawn(async { 14 }, |me, output, _| {
3280                        me.count = output;
3281                    })
3282                })
3283                .await;
3284            app.read(|ctx| assert_eq!(handle.read(ctx).count, 14));
3285        });
3286    }
3287
3288    #[test]
3289    fn test_spawn_stream_local_from_view() {
3290        #[derive(Default)]
3291        struct View {
3292            events: Vec<Option<usize>>,
3293        }
3294
3295        impl Entity for View {
3296            type Event = ();
3297        }
3298
3299        impl super::View for View {
3300            fn render<'a>(&self, _: &AppContext) -> ElementBox {
3301                Empty::new().boxed()
3302            }
3303
3304            fn ui_name() -> &'static str {
3305                "View"
3306            }
3307        }
3308
3309        App::test_async((), |mut app| async move {
3310            let (_, handle) = app.add_window(|_| View::default());
3311            handle
3312                .update(&mut app, |_, c| {
3313                    c.spawn_stream(
3314                        smol::stream::iter(vec![1_usize, 2, 3]),
3315                        |me, output, _| {
3316                            me.events.push(Some(output));
3317                        },
3318                        |me, _| {
3319                            me.events.push(None);
3320                        },
3321                    )
3322                })
3323                .await;
3324
3325            app.read(|ctx| assert_eq!(handle.read(ctx).events, [Some(1), Some(2), Some(3), None]))
3326        });
3327    }
3328
3329    #[test]
3330    fn test_dispatch_action() {
3331        struct ViewA {
3332            id: usize,
3333        }
3334
3335        impl Entity for ViewA {
3336            type Event = ();
3337        }
3338
3339        impl View for ViewA {
3340            fn render<'a>(&self, _: &AppContext) -> ElementBox {
3341                Empty::new().boxed()
3342            }
3343
3344            fn ui_name() -> &'static str {
3345                "View"
3346            }
3347        }
3348
3349        struct ViewB {
3350            id: usize,
3351        }
3352
3353        impl Entity for ViewB {
3354            type Event = ();
3355        }
3356
3357        impl View for ViewB {
3358            fn render<'a>(&self, _: &AppContext) -> ElementBox {
3359                Empty::new().boxed()
3360            }
3361
3362            fn ui_name() -> &'static str {
3363                "View"
3364            }
3365        }
3366
3367        struct ActionArg {
3368            foo: String,
3369        }
3370
3371        App::test((), |app| {
3372            let actions = Rc::new(RefCell::new(Vec::new()));
3373
3374            let actions_clone = actions.clone();
3375            app.add_global_action("action", move |_: &ActionArg, _: &mut MutableAppContext| {
3376                actions_clone.borrow_mut().push("global a".to_string());
3377            });
3378
3379            let actions_clone = actions.clone();
3380            app.add_global_action("action", move |_: &ActionArg, _: &mut MutableAppContext| {
3381                actions_clone.borrow_mut().push("global b".to_string());
3382            });
3383
3384            let actions_clone = actions.clone();
3385            app.add_action("action", move |view: &mut ViewA, arg: &ActionArg, ctx| {
3386                assert_eq!(arg.foo, "bar");
3387                ctx.propagate_action();
3388                actions_clone.borrow_mut().push(format!("{} a", view.id));
3389            });
3390
3391            let actions_clone = actions.clone();
3392            app.add_action("action", move |view: &mut ViewA, _: &ActionArg, ctx| {
3393                if view.id != 1 {
3394                    ctx.propagate_action();
3395                }
3396                actions_clone.borrow_mut().push(format!("{} b", view.id));
3397            });
3398
3399            let actions_clone = actions.clone();
3400            app.add_action("action", move |view: &mut ViewB, _: &ActionArg, ctx| {
3401                ctx.propagate_action();
3402                actions_clone.borrow_mut().push(format!("{} c", view.id));
3403            });
3404
3405            let actions_clone = actions.clone();
3406            app.add_action("action", move |view: &mut ViewB, _: &ActionArg, ctx| {
3407                ctx.propagate_action();
3408                actions_clone.borrow_mut().push(format!("{} d", view.id));
3409            });
3410
3411            let (window_id, view_1) = app.add_window(|_| ViewA { id: 1 });
3412            let view_2 = app.add_view(window_id, |_| ViewB { id: 2 });
3413            let view_3 = app.add_view(window_id, |_| ViewA { id: 3 });
3414            let view_4 = app.add_view(window_id, |_| ViewB { id: 4 });
3415
3416            app.dispatch_action(
3417                window_id,
3418                vec![view_1.id(), view_2.id(), view_3.id(), view_4.id()],
3419                "action",
3420                ActionArg { foo: "bar".into() },
3421            );
3422
3423            assert_eq!(
3424                *actions.borrow(),
3425                vec!["4 d", "4 c", "3 b", "3 a", "2 d", "2 c", "1 b"]
3426            );
3427
3428            // Remove view_1, which doesn't propagate the action
3429            actions.borrow_mut().clear();
3430            app.dispatch_action(
3431                window_id,
3432                vec![view_2.id(), view_3.id(), view_4.id()],
3433                "action",
3434                ActionArg { foo: "bar".into() },
3435            );
3436
3437            assert_eq!(
3438                *actions.borrow(),
3439                vec!["4 d", "4 c", "3 b", "3 a", "2 d", "2 c", "global b", "global a"]
3440            );
3441        })
3442    }
3443
3444    #[test]
3445    fn test_dispatch_keystroke() {
3446        use std::cell::Cell;
3447
3448        #[derive(Clone)]
3449        struct ActionArg {
3450            key: String,
3451        }
3452
3453        struct View {
3454            id: usize,
3455            keymap_context: keymap::Context,
3456        }
3457
3458        impl Entity for View {
3459            type Event = ();
3460        }
3461
3462        impl super::View for View {
3463            fn render<'a>(&self, _: &AppContext) -> ElementBox {
3464                Empty::new().boxed()
3465            }
3466
3467            fn ui_name() -> &'static str {
3468                "View"
3469            }
3470
3471            fn keymap_context(&self, _: &AppContext) -> keymap::Context {
3472                self.keymap_context.clone()
3473            }
3474        }
3475
3476        impl View {
3477            fn new(id: usize) -> Self {
3478                View {
3479                    id,
3480                    keymap_context: keymap::Context::default(),
3481                }
3482            }
3483        }
3484
3485        App::test((), |app| {
3486            let mut view_1 = View::new(1);
3487            let mut view_2 = View::new(2);
3488            let mut view_3 = View::new(3);
3489            view_1.keymap_context.set.insert("a".into());
3490            view_2.keymap_context.set.insert("b".into());
3491            view_3.keymap_context.set.insert("c".into());
3492
3493            let (window_id, view_1) = app.add_window(|_| view_1);
3494            let view_2 = app.add_view(window_id, |_| view_2);
3495            let view_3 = app.add_view(window_id, |_| view_3);
3496
3497            // This keymap's only binding dispatches an action on view 2 because that view will have
3498            // "a" and "b" in its context, but not "c".
3499            let binding = keymap::Binding::new("a", "action", Some("a && b && !c"))
3500                .with_arg(ActionArg { key: "a".into() });
3501            app.add_bindings(vec![binding]);
3502
3503            let handled_action = Rc::new(Cell::new(false));
3504            let handled_action_clone = handled_action.clone();
3505            app.add_action("action", move |view: &mut View, arg: &ActionArg, _ctx| {
3506                handled_action_clone.set(true);
3507                assert_eq!(view.id, 2);
3508                assert_eq!(arg.key, "a");
3509            });
3510
3511            app.dispatch_keystroke(
3512                window_id,
3513                vec![view_1.id(), view_2.id(), view_3.id()],
3514                &Keystroke::parse("a").unwrap(),
3515            )
3516            .unwrap();
3517
3518            assert!(handled_action.get());
3519        });
3520    }
3521
3522    #[test]
3523    fn test_model_condition() {
3524        struct Counter(usize);
3525
3526        impl super::Entity for Counter {
3527            type Event = ();
3528        }
3529
3530        impl Counter {
3531            fn inc(&mut self, ctx: &mut ModelContext<Self>) {
3532                self.0 += 1;
3533                ctx.notify();
3534            }
3535        }
3536
3537        App::test_async((), |mut app| async move {
3538            let model = app.add_model(|_| Counter(0));
3539
3540            let condition1 = model.condition(&app, |model, _| model.0 == 2);
3541            let condition2 = model.condition(&app, |model, _| model.0 == 3);
3542            smol::pin!(condition1, condition2);
3543
3544            model.update(&mut app, |model, ctx| model.inc(ctx));
3545            assert_eq!(poll_once(&mut condition1).await, None);
3546            assert_eq!(poll_once(&mut condition2).await, None);
3547
3548            model.update(&mut app, |model, ctx| model.inc(ctx));
3549            assert_eq!(poll_once(&mut condition1).await, Some(()));
3550            assert_eq!(poll_once(&mut condition2).await, None);
3551
3552            model.update(&mut app, |model, ctx| model.inc(ctx));
3553            assert_eq!(poll_once(&mut condition2).await, Some(()));
3554
3555            // Broadcast channel should be removed if no conditions remain on next notification.
3556            model.update(&mut app, |_, ctx| ctx.notify());
3557            app.update(|ctx| assert!(ctx.async_observations.get(&model.id()).is_none()));
3558        });
3559    }
3560
3561    #[test]
3562    #[should_panic]
3563    fn test_model_condition_timeout() {
3564        struct Model;
3565
3566        impl super::Entity for Model {
3567            type Event = ();
3568        }
3569
3570        App::test_async((), |mut app| async move {
3571            let model = app.add_model(|_| Model);
3572            model.condition(&app, |_, _| false).await;
3573        });
3574    }
3575
3576    #[test]
3577    #[should_panic(expected = "model dropped with pending condition")]
3578    fn test_model_condition_panic_on_drop() {
3579        struct Model;
3580
3581        impl super::Entity for Model {
3582            type Event = ();
3583        }
3584
3585        App::test_async((), |mut app| async move {
3586            let model = app.add_model(|_| Model);
3587            let condition = model.condition(&app, |_, _| false);
3588            app.update(|_| drop(model));
3589            condition.await;
3590        });
3591    }
3592
3593    #[test]
3594    fn test_view_condition() {
3595        struct Counter(usize);
3596
3597        impl super::Entity for Counter {
3598            type Event = ();
3599        }
3600
3601        impl super::View for Counter {
3602            fn ui_name() -> &'static str {
3603                "test view"
3604            }
3605
3606            fn render(&self, _: &AppContext) -> ElementBox {
3607                Empty::new().boxed()
3608            }
3609        }
3610
3611        impl Counter {
3612            fn inc(&mut self, ctx: &mut ViewContext<Self>) {
3613                self.0 += 1;
3614                ctx.notify();
3615            }
3616        }
3617
3618        App::test_async((), |mut app| async move {
3619            let (_, view) = app.add_window(|_| Counter(0));
3620
3621            let condition1 = view.condition(&app, |view, _| view.0 == 2);
3622            let condition2 = view.condition(&app, |view, _| view.0 == 3);
3623            smol::pin!(condition1, condition2);
3624
3625            view.update(&mut app, |view, ctx| view.inc(ctx));
3626            assert_eq!(poll_once(&mut condition1).await, None);
3627            assert_eq!(poll_once(&mut condition2).await, None);
3628
3629            view.update(&mut app, |view, ctx| view.inc(ctx));
3630            assert_eq!(poll_once(&mut condition1).await, Some(()));
3631            assert_eq!(poll_once(&mut condition2).await, None);
3632
3633            view.update(&mut app, |view, ctx| view.inc(ctx));
3634            assert_eq!(poll_once(&mut condition2).await, Some(()));
3635
3636            // Broadcast channel should be removed if no conditions remain on next notification.
3637            view.update(&mut app, |_, ctx| ctx.notify());
3638            app.update(|ctx| assert!(ctx.async_observations.get(&view.id()).is_none()));
3639        });
3640    }
3641
3642    #[test]
3643    #[should_panic]
3644    fn test_view_condition_timeout() {
3645        struct View;
3646
3647        impl super::Entity for View {
3648            type Event = ();
3649        }
3650
3651        impl super::View for View {
3652            fn ui_name() -> &'static str {
3653                "test view"
3654            }
3655
3656            fn render(&self, _: &AppContext) -> ElementBox {
3657                Empty::new().boxed()
3658            }
3659        }
3660
3661        App::test_async((), |mut app| async move {
3662            let (_, view) = app.add_window(|_| View);
3663            view.condition(&app, |_, _| false).await;
3664        });
3665    }
3666
3667    #[test]
3668    #[should_panic(expected = "model dropped with pending condition")]
3669    fn test_view_condition_panic_on_drop() {
3670        struct View;
3671
3672        impl super::Entity for View {
3673            type Event = ();
3674        }
3675
3676        impl super::View for View {
3677            fn ui_name() -> &'static str {
3678                "test view"
3679            }
3680
3681            fn render(&self, _: &AppContext) -> ElementBox {
3682                Empty::new().boxed()
3683            }
3684        }
3685
3686        App::test_async((), |mut app| async move {
3687            let window_id = app.add_window(|_| View).0;
3688            let view = app.add_view(window_id, |_| View);
3689
3690            let condition = view.condition(&app, |_, _| false);
3691            app.update(|_| drop(view));
3692            condition.await;
3693        });
3694    }
3695
3696    // #[test]
3697    // fn test_ui_and_window_updates() {
3698    //     struct View {
3699    //         count: usize,
3700    //     }
3701
3702    //     impl Entity for View {
3703    //         type Event = ();
3704    //     }
3705
3706    //     impl super::View for View {
3707    //         fn render<'a>(&self, _: &AppContext) -> ElementBox {
3708    //             Empty::new().boxed()
3709    //         }
3710
3711    //         fn ui_name() -> &'static str {
3712    //             "View"
3713    //         }
3714    //     }
3715
3716    //     App::test(|app| async move {
3717    //         let (window_id, _) = app.add_window(|_| View { count: 3 });
3718    //         let view_1 = app.add_view(window_id, |_| View { count: 1 });
3719    //         let view_2 = app.add_view(window_id, |_| View { count: 2 });
3720
3721    //         // Ensure that registering for UI updates after mutating the app still gives us all the
3722    //         // updates.
3723    //         let ui_updates = Rc::new(RefCell::new(Vec::new()));
3724    //         let ui_updates_ = ui_updates.clone();
3725    //         app.on_ui_update(move |update, _| ui_updates_.borrow_mut().push(update));
3726
3727    //         assert_eq!(
3728    //             ui_updates.borrow_mut().drain(..).collect::<Vec<_>>(),
3729    //             vec![UiUpdate::OpenWindow {
3730    //                 window_id,
3731    //                 width: 1024.0,
3732    //                 height: 768.0,
3733    //             }]
3734    //         );
3735
3736    //         let window_invalidations = Rc::new(RefCell::new(Vec::new()));
3737    //         let window_invalidations_ = window_invalidations.clone();
3738    //         app.on_window_invalidated(window_id, move |update, _| {
3739    //             window_invalidations_.borrow_mut().push(update)
3740    //         });
3741
3742    //         let view_2_id = view_2.id();
3743    //         view_1.update(app, |view, ctx| {
3744    //             view.count = 7;
3745    //             ctx.notify();
3746    //             drop(view_2);
3747    //         });
3748
3749    //         let invalidation = window_invalidations.borrow_mut().drain(..).next().unwrap();
3750    //         assert_eq!(invalidation.updated.len(), 1);
3751    //         assert!(invalidation.updated.contains(&view_1.id()));
3752    //         assert_eq!(invalidation.removed, vec![view_2_id]);
3753
3754    //         let view_3 = view_1.update(app, |_, ctx| ctx.add_view(|_| View { count: 8 }));
3755
3756    //         let invalidation = window_invalidations.borrow_mut().drain(..).next().unwrap();
3757    //         assert_eq!(invalidation.updated.len(), 1);
3758    //         assert!(invalidation.updated.contains(&view_3.id()));
3759    //         assert!(invalidation.removed.is_empty());
3760
3761    //         view_3
3762    //             .update(app, |_, ctx| {
3763    //                 ctx.spawn_local(async { 9 }, |me, output, ctx| {
3764    //                     me.count = output;
3765    //                     ctx.notify();
3766    //                 })
3767    //             })
3768    //             .await;
3769
3770    //         let invalidation = window_invalidations.borrow_mut().drain(..).next().unwrap();
3771    //         assert_eq!(invalidation.updated.len(), 1);
3772    //         assert!(invalidation.updated.contains(&view_3.id()));
3773    //         assert!(invalidation.removed.is_empty());
3774    //     });
3775    // }
3776}