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