app.rs

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