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 platform::Event;
  16use postage::{mpsc, sink::Sink as _, stream::Stream as _};
  17use smol::prelude::*;
  18use std::{
  19    any::{type_name, Any, TypeId},
  20    cell::RefCell,
  21    collections::{hash_map::Entry, HashMap, HashSet, VecDeque},
  22    fmt::{self, Debug},
  23    hash::{Hash, Hasher},
  24    marker::PhantomData,
  25    ops::{Deref, DerefMut},
  26    path::{Path, PathBuf},
  27    rc::{self, Rc},
  28    sync::{Arc, Weak},
  29    time::Duration,
  30};
  31
  32pub trait Entity: 'static + Send + Sync {
  33    type Event;
  34
  35    fn release(&mut self, _: &mut MutableAppContext) {}
  36}
  37
  38pub trait View: Entity + Sized {
  39    fn ui_name() -> &'static str;
  40    fn render(&self, cx: &RenderContext<'_, Self>) -> ElementBox;
  41    fn on_focus(&mut self, _: &mut ViewContext<Self>) {}
  42    fn on_blur(&mut self, _: &mut ViewContext<Self>) {}
  43    fn keymap_context(&self, _: &AppContext) -> keymap::Context {
  44        Self::default_keymap_context()
  45    }
  46    fn default_keymap_context() -> keymap::Context {
  47        let mut cx = keymap::Context::default();
  48        cx.set.insert(Self::ui_name().into());
  49        cx
  50    }
  51}
  52
  53pub trait ReadModel {
  54    fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T;
  55}
  56
  57pub trait ReadModelWith {
  58    fn read_model_with<E: Entity, F: FnOnce(&E, &AppContext) -> T, T>(
  59        &self,
  60        handle: &ModelHandle<E>,
  61        read: F,
  62    ) -> T;
  63}
  64
  65pub trait UpdateModel {
  66    fn update_model<T, F, S>(&mut self, handle: &ModelHandle<T>, update: F) -> S
  67    where
  68        T: Entity,
  69        F: FnOnce(&mut T, &mut ModelContext<T>) -> S;
  70}
  71
  72pub trait ReadView {
  73    fn read_view<T: View>(&self, handle: &ViewHandle<T>) -> &T;
  74}
  75
  76pub trait ReadViewWith {
  77    fn read_view_with<V, F, T>(&self, handle: &ViewHandle<V>, read: F) -> T
  78    where
  79        V: View,
  80        F: FnOnce(&V, &AppContext) -> T;
  81}
  82
  83pub trait UpdateView {
  84    fn update_view<T, F, S>(&mut self, handle: &ViewHandle<T>, update: F) -> S
  85    where
  86        T: View,
  87        F: FnOnce(&mut T, &mut ViewContext<T>) -> S;
  88}
  89
  90pub struct Menu<'a> {
  91    pub name: &'a str,
  92    pub items: Vec<MenuItem<'a>>,
  93}
  94
  95pub enum MenuItem<'a> {
  96    Action {
  97        name: &'a str,
  98        keystroke: Option<&'a str>,
  99        action: &'a str,
 100        arg: Option<Box<dyn Any + 'static>>,
 101    },
 102    Separator,
 103}
 104
 105#[derive(Clone)]
 106pub struct App(Rc<RefCell<MutableAppContext>>);
 107
 108#[derive(Clone)]
 109pub struct AsyncAppContext(Rc<RefCell<MutableAppContext>>);
 110
 111pub struct BackgroundAppContext(*const RefCell<MutableAppContext>);
 112
 113#[derive(Clone)]
 114pub struct TestAppContext {
 115    cx: Rc<RefCell<MutableAppContext>>,
 116    foreground_platform: Rc<platform::test::ForegroundPlatform>,
 117}
 118
 119impl App {
 120    pub fn new(asset_source: impl AssetSource) -> Result<Self> {
 121        let platform = platform::current::platform();
 122        let foreground_platform = platform::current::foreground_platform();
 123        let foreground = Rc::new(executor::Foreground::platform(platform.dispatcher())?);
 124        let app = Self(Rc::new(RefCell::new(MutableAppContext::new(
 125            foreground,
 126            Arc::new(executor::Background::new()),
 127            platform.clone(),
 128            foreground_platform.clone(),
 129            Arc::new(FontCache::new(platform.fonts())),
 130            asset_source,
 131        ))));
 132
 133        let cx = app.0.clone();
 134        foreground_platform.on_menu_command(Box::new(move |command, arg| {
 135            let mut cx = cx.borrow_mut();
 136            if let Some(key_window_id) = cx.cx.platform.key_window_id() {
 137                if let Some((presenter, _)) = cx.presenters_and_platform_windows.get(&key_window_id)
 138                {
 139                    let presenter = presenter.clone();
 140                    let path = presenter.borrow().dispatch_path(cx.as_ref());
 141                    cx.dispatch_action_any(key_window_id, &path, command, arg.unwrap_or(&()));
 142                } else {
 143                    cx.dispatch_global_action_any(command, arg.unwrap_or(&()));
 144                }
 145            } else {
 146                cx.dispatch_global_action_any(command, arg.unwrap_or(&()));
 147            }
 148        }));
 149
 150        app.0.borrow_mut().weak_self = Some(Rc::downgrade(&app.0));
 151        Ok(app)
 152    }
 153
 154    pub fn on_become_active<F>(self, mut callback: F) -> Self
 155    where
 156        F: 'static + FnMut(&mut MutableAppContext),
 157    {
 158        let cx = self.0.clone();
 159        self.0
 160            .borrow_mut()
 161            .foreground_platform
 162            .on_become_active(Box::new(move || callback(&mut *cx.borrow_mut())));
 163        self
 164    }
 165
 166    pub fn on_resign_active<F>(self, mut callback: F) -> Self
 167    where
 168        F: 'static + FnMut(&mut MutableAppContext),
 169    {
 170        let cx = self.0.clone();
 171        self.0
 172            .borrow_mut()
 173            .foreground_platform
 174            .on_resign_active(Box::new(move || callback(&mut *cx.borrow_mut())));
 175        self
 176    }
 177
 178    pub fn on_event<F>(self, mut callback: F) -> Self
 179    where
 180        F: 'static + FnMut(Event, &mut MutableAppContext) -> bool,
 181    {
 182        let cx = self.0.clone();
 183        self.0
 184            .borrow_mut()
 185            .foreground_platform
 186            .on_event(Box::new(move |event| {
 187                callback(event, &mut *cx.borrow_mut())
 188            }));
 189        self
 190    }
 191
 192    pub fn on_open_files<F>(self, mut callback: F) -> Self
 193    where
 194        F: 'static + FnMut(Vec<PathBuf>, &mut MutableAppContext),
 195    {
 196        let cx = self.0.clone();
 197        self.0
 198            .borrow_mut()
 199            .foreground_platform
 200            .on_open_files(Box::new(move |paths| {
 201                callback(paths, &mut *cx.borrow_mut())
 202            }));
 203        self
 204    }
 205
 206    pub fn run<F>(self, on_finish_launching: F)
 207    where
 208        F: 'static + FnOnce(&mut MutableAppContext),
 209    {
 210        let platform = self.0.borrow().foreground_platform.clone();
 211        platform.run(Box::new(move || {
 212            let mut cx = self.0.borrow_mut();
 213            on_finish_launching(&mut *cx);
 214        }))
 215    }
 216
 217    pub fn font_cache(&self) -> Arc<FontCache> {
 218        self.0.borrow().cx.font_cache.clone()
 219    }
 220
 221    fn update<T, F: FnOnce(&mut MutableAppContext) -> T>(&mut self, callback: F) -> T {
 222        let mut state = self.0.borrow_mut();
 223        state.pending_flushes += 1;
 224        let result = callback(&mut *state);
 225        state.flush_effects();
 226        result
 227    }
 228}
 229
 230impl TestAppContext {
 231    pub fn new(
 232        foreground_platform: Rc<platform::test::ForegroundPlatform>,
 233        platform: Arc<dyn Platform>,
 234        foreground: Rc<executor::Foreground>,
 235        background: Arc<executor::Background>,
 236        font_cache: Arc<FontCache>,
 237        first_entity_id: usize,
 238    ) -> Self {
 239        let mut cx = MutableAppContext::new(
 240            foreground.clone(),
 241            background,
 242            platform,
 243            foreground_platform.clone(),
 244            font_cache,
 245            (),
 246        );
 247        cx.next_entity_id = first_entity_id;
 248        let cx = TestAppContext {
 249            cx: Rc::new(RefCell::new(cx)),
 250            foreground_platform,
 251        };
 252        cx.cx.borrow_mut().weak_self = Some(Rc::downgrade(&cx.cx));
 253        cx
 254    }
 255
 256    pub fn dispatch_action<T: 'static + Any>(
 257        &self,
 258        window_id: usize,
 259        responder_chain: Vec<usize>,
 260        name: &str,
 261        arg: T,
 262    ) {
 263        self.cx.borrow_mut().dispatch_action_any(
 264            window_id,
 265            &responder_chain,
 266            name,
 267            Box::new(arg).as_ref(),
 268        );
 269    }
 270
 271    pub fn dispatch_global_action<T: 'static + Any>(&self, name: &str, arg: T) {
 272        self.cx.borrow_mut().dispatch_global_action(name, arg);
 273    }
 274
 275    pub fn dispatch_keystroke(
 276        &self,
 277        window_id: usize,
 278        responder_chain: Vec<usize>,
 279        keystroke: &Keystroke,
 280    ) -> Result<bool> {
 281        let mut state = self.cx.borrow_mut();
 282        state.dispatch_keystroke(window_id, responder_chain, keystroke)
 283    }
 284
 285    pub fn add_model<T, F>(&mut self, build_model: F) -> ModelHandle<T>
 286    where
 287        T: Entity,
 288        F: FnOnce(&mut ModelContext<T>) -> T,
 289    {
 290        let mut state = self.cx.borrow_mut();
 291        state.pending_flushes += 1;
 292        let handle = state.add_model(build_model);
 293        state.flush_effects();
 294        handle
 295    }
 296
 297    pub fn add_window<T, F>(&mut self, build_root_view: F) -> (usize, ViewHandle<T>)
 298    where
 299        T: View,
 300        F: FnOnce(&mut ViewContext<T>) -> T,
 301    {
 302        self.cx
 303            .borrow_mut()
 304            .add_window(Default::default(), build_root_view)
 305    }
 306
 307    pub fn window_ids(&self) -> Vec<usize> {
 308        self.cx.borrow().window_ids().collect()
 309    }
 310
 311    pub fn root_view<T: View>(&self, window_id: usize) -> Option<ViewHandle<T>> {
 312        self.cx.borrow().root_view(window_id)
 313    }
 314
 315    pub fn add_view<T, F>(&mut self, window_id: usize, build_view: F) -> ViewHandle<T>
 316    where
 317        T: View,
 318        F: FnOnce(&mut ViewContext<T>) -> T,
 319    {
 320        let mut state = self.cx.borrow_mut();
 321        state.pending_flushes += 1;
 322        let handle = state.add_view(window_id, build_view);
 323        state.flush_effects();
 324        handle
 325    }
 326
 327    pub fn add_option_view<T, F>(
 328        &mut self,
 329        window_id: usize,
 330        build_view: F,
 331    ) -> Option<ViewHandle<T>>
 332    where
 333        T: View,
 334        F: FnOnce(&mut ViewContext<T>) -> Option<T>,
 335    {
 336        let mut state = self.cx.borrow_mut();
 337        state.pending_flushes += 1;
 338        let handle = state.add_option_view(window_id, build_view);
 339        state.flush_effects();
 340        handle
 341    }
 342
 343    pub fn read<T, F: FnOnce(&AppContext) -> T>(&self, callback: F) -> T {
 344        callback(self.cx.borrow().as_ref())
 345    }
 346
 347    pub fn update<T, F: FnOnce(&mut MutableAppContext) -> T>(&mut self, callback: F) -> T {
 348        let mut state = self.cx.borrow_mut();
 349        // Don't increment pending flushes in order to effects to be flushed before the callback
 350        // completes, which is helpful in tests.
 351        let result = callback(&mut *state);
 352        // Flush effects after the callback just in case there are any. This can happen in edge
 353        // cases such as the closure dropping handles.
 354        state.flush_effects();
 355        result
 356    }
 357
 358    pub fn to_async(&self) -> AsyncAppContext {
 359        AsyncAppContext(self.cx.clone())
 360    }
 361
 362    pub fn font_cache(&self) -> Arc<FontCache> {
 363        self.cx.borrow().cx.font_cache.clone()
 364    }
 365
 366    pub fn platform(&self) -> Arc<dyn platform::Platform> {
 367        self.cx.borrow().cx.platform.clone()
 368    }
 369
 370    pub fn foreground(&self) -> Rc<executor::Foreground> {
 371        self.cx.borrow().foreground().clone()
 372    }
 373
 374    pub fn background(&self) -> Arc<executor::Background> {
 375        self.cx.borrow().background().clone()
 376    }
 377
 378    pub fn simulate_new_path_selection(&self, result: impl FnOnce(PathBuf) -> Option<PathBuf>) {
 379        self.foreground_platform.simulate_new_path_selection(result);
 380    }
 381
 382    pub fn did_prompt_for_new_path(&self) -> bool {
 383        self.foreground_platform.as_ref().did_prompt_for_new_path()
 384    }
 385
 386    pub fn simulate_prompt_answer(&self, window_id: usize, answer: usize) {
 387        let mut state = self.cx.borrow_mut();
 388        let (_, window) = state
 389            .presenters_and_platform_windows
 390            .get_mut(&window_id)
 391            .unwrap();
 392        let test_window = window
 393            .as_any_mut()
 394            .downcast_mut::<platform::test::Window>()
 395            .unwrap();
 396        let callback = test_window
 397            .last_prompt
 398            .take()
 399            .expect("prompt was not called");
 400        (callback)(answer);
 401    }
 402}
 403
 404impl AsyncAppContext {
 405    pub fn spawn<F, Fut, T>(&self, f: F) -> Task<T>
 406    where
 407        F: FnOnce(AsyncAppContext) -> Fut,
 408        Fut: 'static + Future<Output = T>,
 409        T: 'static,
 410    {
 411        self.0.borrow().foreground.spawn(f(self.clone()))
 412    }
 413
 414    pub fn read<T, F: FnOnce(&AppContext) -> T>(&mut self, callback: F) -> T {
 415        callback(self.0.borrow().as_ref())
 416    }
 417
 418    pub fn update<T, F: FnOnce(&mut MutableAppContext) -> T>(&mut self, callback: F) -> T {
 419        let mut state = self.0.borrow_mut();
 420        state.pending_flushes += 1;
 421        let result = callback(&mut *state);
 422        state.flush_effects();
 423        result
 424    }
 425
 426    pub fn add_model<T, F>(&mut self, build_model: F) -> ModelHandle<T>
 427    where
 428        T: Entity,
 429        F: FnOnce(&mut ModelContext<T>) -> T,
 430    {
 431        self.update(|cx| cx.add_model(build_model))
 432    }
 433
 434    pub fn platform(&self) -> Arc<dyn Platform> {
 435        self.0.borrow().platform()
 436    }
 437
 438    pub fn foreground(&self) -> Rc<executor::Foreground> {
 439        self.0.borrow().foreground.clone()
 440    }
 441
 442    pub fn background(&self) -> Arc<executor::Background> {
 443        self.0.borrow().cx.background.clone()
 444    }
 445}
 446
 447impl UpdateModel for AsyncAppContext {
 448    fn update_model<T, F, S>(&mut self, handle: &ModelHandle<T>, update: F) -> S
 449    where
 450        T: Entity,
 451        F: FnOnce(&mut T, &mut ModelContext<T>) -> S,
 452    {
 453        let mut state = self.0.borrow_mut();
 454        state.pending_flushes += 1;
 455        let result = state.update_model(handle, update);
 456        state.flush_effects();
 457        result
 458    }
 459}
 460
 461impl ReadModelWith for AsyncAppContext {
 462    fn read_model_with<E: Entity, F: FnOnce(&E, &AppContext) -> T, T>(
 463        &self,
 464        handle: &ModelHandle<E>,
 465        read: F,
 466    ) -> T {
 467        let cx = self.0.borrow();
 468        let cx = cx.as_ref();
 469        read(handle.read(cx), cx)
 470    }
 471}
 472
 473impl UpdateView for AsyncAppContext {
 474    fn update_view<T, F, S>(&mut self, handle: &ViewHandle<T>, update: F) -> S
 475    where
 476        T: View,
 477        F: FnOnce(&mut T, &mut ViewContext<T>) -> S,
 478    {
 479        let mut state = self.0.borrow_mut();
 480        state.pending_flushes += 1;
 481        let result = state.update_view(handle, update);
 482        state.flush_effects();
 483        result
 484    }
 485}
 486
 487impl ReadViewWith for AsyncAppContext {
 488    fn read_view_with<V, F, T>(&self, handle: &ViewHandle<V>, read: F) -> T
 489    where
 490        V: View,
 491        F: FnOnce(&V, &AppContext) -> T,
 492    {
 493        let cx = self.0.borrow();
 494        let cx = cx.as_ref();
 495        read(handle.read(cx), cx)
 496    }
 497}
 498
 499impl UpdateModel for TestAppContext {
 500    fn update_model<T, F, S>(&mut self, handle: &ModelHandle<T>, update: F) -> S
 501    where
 502        T: Entity,
 503        F: FnOnce(&mut T, &mut ModelContext<T>) -> S,
 504    {
 505        let mut state = self.cx.borrow_mut();
 506        state.pending_flushes += 1;
 507        let result = state.update_model(handle, update);
 508        state.flush_effects();
 509        result
 510    }
 511}
 512
 513impl ReadModelWith for TestAppContext {
 514    fn read_model_with<E: Entity, F: FnOnce(&E, &AppContext) -> T, T>(
 515        &self,
 516        handle: &ModelHandle<E>,
 517        read: F,
 518    ) -> T {
 519        let cx = self.cx.borrow();
 520        let cx = cx.as_ref();
 521        read(handle.read(cx), cx)
 522    }
 523}
 524
 525impl UpdateView for TestAppContext {
 526    fn update_view<T, F, S>(&mut self, handle: &ViewHandle<T>, update: F) -> S
 527    where
 528        T: View,
 529        F: FnOnce(&mut T, &mut ViewContext<T>) -> S,
 530    {
 531        let mut state = self.cx.borrow_mut();
 532        state.pending_flushes += 1;
 533        let result = state.update_view(handle, update);
 534        state.flush_effects();
 535        result
 536    }
 537}
 538
 539impl ReadViewWith for TestAppContext {
 540    fn read_view_with<V, F, T>(&self, handle: &ViewHandle<V>, read: F) -> T
 541    where
 542        V: View,
 543        F: FnOnce(&V, &AppContext) -> T,
 544    {
 545        let cx = self.cx.borrow();
 546        let cx = cx.as_ref();
 547        read(handle.read(cx), cx)
 548    }
 549}
 550
 551type ActionCallback =
 552    dyn FnMut(&mut dyn AnyView, &dyn Any, &mut MutableAppContext, usize, usize) -> bool;
 553
 554type GlobalActionCallback = dyn FnMut(&dyn Any, &mut MutableAppContext);
 555
 556pub struct MutableAppContext {
 557    weak_self: Option<rc::Weak<RefCell<Self>>>,
 558    foreground_platform: Rc<dyn platform::ForegroundPlatform>,
 559    assets: Arc<AssetCache>,
 560    cx: AppContext,
 561    actions: HashMap<TypeId, HashMap<String, Vec<Box<ActionCallback>>>>,
 562    global_actions: HashMap<String, Vec<Box<GlobalActionCallback>>>,
 563    keystroke_matcher: keymap::Matcher,
 564    next_entity_id: usize,
 565    next_window_id: usize,
 566    subscriptions: HashMap<usize, Vec<Subscription>>,
 567    model_observations: HashMap<usize, Vec<ModelObservation>>,
 568    view_observations: HashMap<usize, Vec<ViewObservation>>,
 569    presenters_and_platform_windows:
 570        HashMap<usize, (Rc<RefCell<Presenter>>, Box<dyn platform::Window>)>,
 571    debug_elements_callbacks: HashMap<usize, Box<dyn Fn(&AppContext) -> crate::json::Value>>,
 572    foreground: Rc<executor::Foreground>,
 573    pending_effects: VecDeque<Effect>,
 574    pending_flushes: usize,
 575    flushing_effects: bool,
 576}
 577
 578impl MutableAppContext {
 579    fn new(
 580        foreground: Rc<executor::Foreground>,
 581        background: Arc<executor::Background>,
 582        platform: Arc<dyn platform::Platform>,
 583        foreground_platform: Rc<dyn platform::ForegroundPlatform>,
 584        font_cache: Arc<FontCache>,
 585        asset_source: impl AssetSource,
 586    ) -> Self {
 587        Self {
 588            weak_self: None,
 589            foreground_platform,
 590            assets: Arc::new(AssetCache::new(asset_source)),
 591            cx: AppContext {
 592                models: Default::default(),
 593                views: Default::default(),
 594                windows: Default::default(),
 595                values: Default::default(),
 596                ref_counts: Arc::new(Mutex::new(RefCounts::default())),
 597                background,
 598                font_cache,
 599                platform,
 600            },
 601            actions: HashMap::new(),
 602            global_actions: HashMap::new(),
 603            keystroke_matcher: keymap::Matcher::default(),
 604            next_entity_id: 0,
 605            next_window_id: 0,
 606            subscriptions: HashMap::new(),
 607            model_observations: HashMap::new(),
 608            view_observations: HashMap::new(),
 609            presenters_and_platform_windows: HashMap::new(),
 610            debug_elements_callbacks: HashMap::new(),
 611            foreground,
 612            pending_effects: VecDeque::new(),
 613            pending_flushes: 0,
 614            flushing_effects: false,
 615        }
 616    }
 617
 618    pub fn upgrade(&self) -> App {
 619        App(self.weak_self.as_ref().unwrap().upgrade().unwrap())
 620    }
 621
 622    pub fn platform(&self) -> Arc<dyn platform::Platform> {
 623        self.cx.platform.clone()
 624    }
 625
 626    pub fn font_cache(&self) -> &Arc<FontCache> {
 627        &self.cx.font_cache
 628    }
 629
 630    pub fn foreground(&self) -> &Rc<executor::Foreground> {
 631        &self.foreground
 632    }
 633
 634    pub fn background(&self) -> &Arc<executor::Background> {
 635        &self.cx.background
 636    }
 637
 638    pub fn on_debug_elements<F>(&mut self, window_id: usize, callback: F)
 639    where
 640        F: 'static + Fn(&AppContext) -> crate::json::Value,
 641    {
 642        self.debug_elements_callbacks
 643            .insert(window_id, Box::new(callback));
 644    }
 645
 646    pub fn debug_elements(&self, window_id: usize) -> Option<crate::json::Value> {
 647        self.debug_elements_callbacks
 648            .get(&window_id)
 649            .map(|debug_elements| debug_elements(&self.cx))
 650    }
 651
 652    pub fn add_action<S, V, T, F>(&mut self, name: S, mut handler: F)
 653    where
 654        S: Into<String>,
 655        V: View,
 656        T: Any,
 657        F: 'static + FnMut(&mut V, &T, &mut ViewContext<V>),
 658    {
 659        let name = name.into();
 660        let name_clone = name.clone();
 661        let handler = Box::new(
 662            move |view: &mut dyn AnyView,
 663                  arg: &dyn Any,
 664                  cx: &mut MutableAppContext,
 665                  window_id: usize,
 666                  view_id: usize| {
 667                match arg.downcast_ref() {
 668                    Some(arg) => {
 669                        let mut cx = ViewContext::new(cx, window_id, view_id);
 670                        handler(
 671                            view.as_any_mut()
 672                                .downcast_mut()
 673                                .expect("downcast is type safe"),
 674                            arg,
 675                            &mut cx,
 676                        );
 677                        cx.halt_action_dispatch
 678                    }
 679                    None => {
 680                        log::error!("Could not downcast argument for action {}", name_clone);
 681                        false
 682                    }
 683                }
 684            },
 685        );
 686
 687        self.actions
 688            .entry(TypeId::of::<V>())
 689            .or_default()
 690            .entry(name)
 691            .or_default()
 692            .push(handler);
 693    }
 694
 695    pub fn add_global_action<S, T, F>(&mut self, name: S, mut handler: F)
 696    where
 697        S: Into<String>,
 698        T: 'static + Any,
 699        F: 'static + FnMut(&T, &mut MutableAppContext),
 700    {
 701        let name = name.into();
 702        let name_clone = name.clone();
 703        let handler = Box::new(move |arg: &dyn Any, cx: &mut MutableAppContext| {
 704            if let Some(arg) = arg.downcast_ref() {
 705                handler(arg, cx);
 706            } else {
 707                log::error!(
 708                    "Could not downcast argument for global action {}",
 709                    name_clone
 710                );
 711            }
 712        });
 713
 714        self.global_actions.entry(name).or_default().push(handler);
 715    }
 716
 717    pub fn window_ids(&self) -> impl Iterator<Item = usize> + '_ {
 718        self.cx.windows.keys().cloned()
 719    }
 720
 721    pub fn root_view<T: View>(&self, window_id: usize) -> Option<ViewHandle<T>> {
 722        self.cx
 723            .windows
 724            .get(&window_id)
 725            .and_then(|window| window.root_view.clone().downcast::<T>())
 726    }
 727
 728    pub fn root_view_id(&self, window_id: usize) -> Option<usize> {
 729        self.cx.root_view_id(window_id)
 730    }
 731
 732    pub fn focused_view_id(&self, window_id: usize) -> Option<usize> {
 733        self.cx.focused_view_id(window_id)
 734    }
 735
 736    pub fn render_view(&self, window_id: usize, view_id: usize) -> Result<ElementBox> {
 737        self.cx.render_view(window_id, view_id)
 738    }
 739
 740    pub fn render_views(&self, window_id: usize) -> HashMap<usize, ElementBox> {
 741        self.cx.render_views(window_id)
 742    }
 743
 744    pub fn update<T, F: FnOnce() -> T>(&mut self, callback: F) -> T {
 745        self.pending_flushes += 1;
 746        let result = callback();
 747        self.flush_effects();
 748        result
 749    }
 750
 751    pub fn set_menus(&mut self, menus: Vec<Menu>) {
 752        self.foreground_platform.set_menus(menus);
 753    }
 754
 755    fn prompt<F>(
 756        &self,
 757        window_id: usize,
 758        level: PromptLevel,
 759        msg: &str,
 760        answers: &[&str],
 761        done_fn: F,
 762    ) where
 763        F: 'static + FnOnce(usize, &mut MutableAppContext),
 764    {
 765        let app = self.weak_self.as_ref().unwrap().upgrade().unwrap();
 766        let foreground = self.foreground.clone();
 767        let (_, window) = &self.presenters_and_platform_windows[&window_id];
 768        window.prompt(
 769            level,
 770            msg,
 771            answers,
 772            Box::new(move |answer| {
 773                foreground
 774                    .spawn(async move { (done_fn)(answer, &mut *app.borrow_mut()) })
 775                    .detach();
 776            }),
 777        );
 778    }
 779
 780    pub fn prompt_for_paths<F>(&self, options: PathPromptOptions, done_fn: F)
 781    where
 782        F: 'static + FnOnce(Option<Vec<PathBuf>>, &mut MutableAppContext),
 783    {
 784        let app = self.weak_self.as_ref().unwrap().upgrade().unwrap();
 785        let foreground = self.foreground.clone();
 786        self.foreground_platform.prompt_for_paths(
 787            options,
 788            Box::new(move |paths| {
 789                foreground
 790                    .spawn(async move { (done_fn)(paths, &mut *app.borrow_mut()) })
 791                    .detach();
 792            }),
 793        );
 794    }
 795
 796    pub fn prompt_for_new_path<F>(&self, directory: &Path, done_fn: F)
 797    where
 798        F: 'static + FnOnce(Option<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_new_path(
 803            directory,
 804            Box::new(move |path| {
 805                foreground
 806                    .spawn(async move { (done_fn)(path, &mut *app.borrow_mut()) })
 807                    .detach();
 808            }),
 809        );
 810    }
 811
 812    pub(crate) fn notify_view(&mut self, window_id: usize, view_id: usize) {
 813        self.pending_effects
 814            .push_back(Effect::ViewNotification { window_id, view_id });
 815    }
 816
 817    pub(crate) fn notify_all_views(&mut self) {
 818        let notifications = self
 819            .views
 820            .keys()
 821            .copied()
 822            .map(|(window_id, view_id)| Effect::ViewNotification { window_id, view_id })
 823            .collect::<Vec<_>>();
 824        self.pending_effects.extend(notifications);
 825    }
 826
 827    pub fn dispatch_action<T: 'static + Any>(
 828        &mut self,
 829        window_id: usize,
 830        responder_chain: Vec<usize>,
 831        name: &str,
 832        arg: T,
 833    ) {
 834        self.dispatch_action_any(window_id, &responder_chain, name, Box::new(arg).as_ref());
 835    }
 836
 837    pub(crate) fn dispatch_action_any(
 838        &mut self,
 839        window_id: usize,
 840        path: &[usize],
 841        name: &str,
 842        arg: &dyn Any,
 843    ) -> bool {
 844        self.pending_flushes += 1;
 845        let mut halted_dispatch = false;
 846
 847        for view_id in path.iter().rev() {
 848            if let Some(mut view) = self.cx.views.remove(&(window_id, *view_id)) {
 849                let type_id = view.as_any().type_id();
 850
 851                if let Some((name, mut handlers)) = self
 852                    .actions
 853                    .get_mut(&type_id)
 854                    .and_then(|h| h.remove_entry(name))
 855                {
 856                    for handler in handlers.iter_mut().rev() {
 857                        let halt_dispatch = handler(view.as_mut(), arg, self, window_id, *view_id);
 858                        if halt_dispatch {
 859                            halted_dispatch = true;
 860                            break;
 861                        }
 862                    }
 863                    self.actions
 864                        .get_mut(&type_id)
 865                        .unwrap()
 866                        .insert(name, handlers);
 867                }
 868
 869                self.cx.views.insert((window_id, *view_id), view);
 870
 871                if halted_dispatch {
 872                    break;
 873                }
 874            }
 875        }
 876
 877        if !halted_dispatch {
 878            self.dispatch_global_action_any(name, arg);
 879        }
 880
 881        self.flush_effects();
 882        halted_dispatch
 883    }
 884
 885    pub fn dispatch_global_action<T: 'static + Any>(&mut self, name: &str, arg: T) {
 886        self.dispatch_global_action_any(name, Box::new(arg).as_ref());
 887    }
 888
 889    fn dispatch_global_action_any(&mut self, name: &str, arg: &dyn Any) {
 890        if let Some((name, mut handlers)) = self.global_actions.remove_entry(name) {
 891            self.pending_flushes += 1;
 892            for handler in handlers.iter_mut().rev() {
 893                handler(arg, self);
 894            }
 895            self.global_actions.insert(name, handlers);
 896            self.flush_effects();
 897        }
 898    }
 899
 900    pub fn add_bindings<T: IntoIterator<Item = keymap::Binding>>(&mut self, bindings: T) {
 901        self.keystroke_matcher.add_bindings(bindings);
 902    }
 903
 904    pub fn dispatch_keystroke(
 905        &mut self,
 906        window_id: usize,
 907        responder_chain: Vec<usize>,
 908        keystroke: &Keystroke,
 909    ) -> Result<bool> {
 910        let mut context_chain = Vec::new();
 911        let mut context = keymap::Context::default();
 912        for view_id in &responder_chain {
 913            if let Some(view) = self.cx.views.get(&(window_id, *view_id)) {
 914                context.extend(view.keymap_context(self.as_ref()));
 915                context_chain.push(context.clone());
 916            } else {
 917                return Err(anyhow!(
 918                    "View {} in responder chain does not exist",
 919                    view_id
 920                ));
 921            }
 922        }
 923
 924        let mut pending = false;
 925        for (i, cx) in context_chain.iter().enumerate().rev() {
 926            match self
 927                .keystroke_matcher
 928                .push_keystroke(keystroke.clone(), responder_chain[i], cx)
 929            {
 930                MatchResult::None => {}
 931                MatchResult::Pending => pending = true,
 932                MatchResult::Action { name, arg } => {
 933                    if self.dispatch_action_any(
 934                        window_id,
 935                        &responder_chain[0..=i],
 936                        &name,
 937                        arg.as_ref().map(|arg| arg.as_ref()).unwrap_or(&()),
 938                    ) {
 939                        return Ok(true);
 940                    }
 941                }
 942            }
 943        }
 944
 945        Ok(pending)
 946    }
 947
 948    pub fn add_model<T, F>(&mut self, build_model: F) -> ModelHandle<T>
 949    where
 950        T: Entity,
 951        F: FnOnce(&mut ModelContext<T>) -> T,
 952    {
 953        self.pending_flushes += 1;
 954        let model_id = post_inc(&mut self.next_entity_id);
 955        let handle = ModelHandle::new(model_id, &self.cx.ref_counts);
 956        let mut cx = ModelContext::new(self, model_id);
 957        let model = build_model(&mut cx);
 958        self.cx.models.insert(model_id, Box::new(model));
 959        self.flush_effects();
 960        handle
 961    }
 962
 963    pub fn add_window<T, F>(
 964        &mut self,
 965        window_options: WindowOptions,
 966        build_root_view: F,
 967    ) -> (usize, ViewHandle<T>)
 968    where
 969        T: View,
 970        F: FnOnce(&mut ViewContext<T>) -> T,
 971    {
 972        self.pending_flushes += 1;
 973        let window_id = post_inc(&mut self.next_window_id);
 974        let root_view = self.add_view(window_id, build_root_view);
 975
 976        self.cx.windows.insert(
 977            window_id,
 978            Window {
 979                root_view: root_view.clone().into(),
 980                focused_view_id: root_view.id(),
 981                invalidation: None,
 982            },
 983        );
 984        self.open_platform_window(window_id, window_options);
 985        root_view.update(self, |view, cx| {
 986            view.on_focus(cx);
 987            cx.notify();
 988        });
 989        self.flush_effects();
 990
 991        (window_id, root_view)
 992    }
 993
 994    pub fn remove_window(&mut self, window_id: usize) {
 995        self.cx.windows.remove(&window_id);
 996        self.presenters_and_platform_windows.remove(&window_id);
 997        self.remove_dropped_entities();
 998    }
 999
1000    fn open_platform_window(&mut self, window_id: usize, window_options: WindowOptions) {
1001        let mut window =
1002            self.cx
1003                .platform
1004                .open_window(window_id, window_options, self.foreground.clone());
1005        let text_layout_cache = TextLayoutCache::new(self.cx.platform.fonts());
1006        let presenter = Rc::new(RefCell::new(Presenter::new(
1007            window_id,
1008            self.cx.font_cache.clone(),
1009            text_layout_cache,
1010            self.assets.clone(),
1011            self,
1012        )));
1013
1014        {
1015            let mut app = self.upgrade();
1016            let presenter = presenter.clone();
1017            window.on_event(Box::new(move |event| {
1018                app.update(|cx| {
1019                    if let Event::KeyDown { keystroke, .. } = &event {
1020                        if cx
1021                            .dispatch_keystroke(
1022                                window_id,
1023                                presenter.borrow().dispatch_path(cx.as_ref()),
1024                                keystroke,
1025                            )
1026                            .unwrap()
1027                        {
1028                            return;
1029                        }
1030                    }
1031
1032                    presenter.borrow_mut().dispatch_event(event, cx);
1033                })
1034            }));
1035        }
1036
1037        {
1038            let mut app = self.upgrade();
1039            let presenter = presenter.clone();
1040            window.on_resize(Box::new(move |window| {
1041                app.update(|cx| {
1042                    let scene = presenter.borrow_mut().build_scene(
1043                        window.size(),
1044                        window.scale_factor(),
1045                        cx,
1046                    );
1047                    window.present_scene(scene);
1048                })
1049            }));
1050        }
1051
1052        {
1053            let mut app = self.upgrade();
1054            window.on_close(Box::new(move || {
1055                app.update(|cx| cx.remove_window(window_id));
1056            }));
1057        }
1058
1059        self.presenters_and_platform_windows
1060            .insert(window_id, (presenter.clone(), window));
1061
1062        self.on_debug_elements(window_id, move |cx| {
1063            presenter.borrow().debug_elements(cx).unwrap()
1064        });
1065    }
1066
1067    pub fn add_view<T, F>(&mut self, window_id: usize, build_view: F) -> ViewHandle<T>
1068    where
1069        T: View,
1070        F: FnOnce(&mut ViewContext<T>) -> T,
1071    {
1072        self.add_option_view(window_id, |cx| Some(build_view(cx)))
1073            .unwrap()
1074    }
1075
1076    pub fn add_option_view<T, F>(
1077        &mut self,
1078        window_id: usize,
1079        build_view: F,
1080    ) -> Option<ViewHandle<T>>
1081    where
1082        T: View,
1083        F: FnOnce(&mut ViewContext<T>) -> Option<T>,
1084    {
1085        let view_id = post_inc(&mut self.next_entity_id);
1086        self.pending_flushes += 1;
1087        let handle = ViewHandle::new(window_id, view_id, &self.cx.ref_counts);
1088        let mut cx = ViewContext::new(self, window_id, view_id);
1089        let handle = if let Some(view) = build_view(&mut cx) {
1090            self.cx.views.insert((window_id, view_id), Box::new(view));
1091            if let Some(window) = self.cx.windows.get_mut(&window_id) {
1092                window
1093                    .invalidation
1094                    .get_or_insert_with(Default::default)
1095                    .updated
1096                    .insert(view_id);
1097            }
1098            Some(handle)
1099        } else {
1100            None
1101        };
1102        self.flush_effects();
1103        handle
1104    }
1105
1106    fn remove_dropped_entities(&mut self) {
1107        loop {
1108            let (dropped_models, dropped_views, dropped_values) =
1109                self.cx.ref_counts.lock().take_dropped();
1110            if dropped_models.is_empty() && dropped_views.is_empty() && dropped_values.is_empty() {
1111                break;
1112            }
1113
1114            for model_id in dropped_models {
1115                self.subscriptions.remove(&model_id);
1116                self.model_observations.remove(&model_id);
1117                let mut model = self.cx.models.remove(&model_id).unwrap();
1118                model.release(self);
1119            }
1120
1121            for (window_id, view_id) in dropped_views {
1122                self.subscriptions.remove(&view_id);
1123                self.model_observations.remove(&view_id);
1124                let mut view = self.cx.views.remove(&(window_id, view_id)).unwrap();
1125                view.release(self);
1126                let change_focus_to = self.cx.windows.get_mut(&window_id).and_then(|window| {
1127                    window
1128                        .invalidation
1129                        .get_or_insert_with(Default::default)
1130                        .removed
1131                        .push(view_id);
1132                    if window.focused_view_id == view_id {
1133                        Some(window.root_view.id())
1134                    } else {
1135                        None
1136                    }
1137                });
1138
1139                if let Some(view_id) = change_focus_to {
1140                    self.focus(window_id, view_id);
1141                }
1142            }
1143
1144            let mut values = self.cx.values.write();
1145            for key in dropped_values {
1146                values.remove(&key);
1147            }
1148        }
1149    }
1150
1151    fn flush_effects(&mut self) {
1152        self.pending_flushes = self.pending_flushes.saturating_sub(1);
1153
1154        if !self.flushing_effects && self.pending_flushes == 0 {
1155            self.flushing_effects = true;
1156
1157            loop {
1158                if let Some(effect) = self.pending_effects.pop_front() {
1159                    match effect {
1160                        Effect::Event { entity_id, payload } => self.emit_event(entity_id, payload),
1161                        Effect::ModelNotification { model_id } => {
1162                            self.notify_model_observers(model_id)
1163                        }
1164                        Effect::ViewNotification { window_id, view_id } => {
1165                            self.notify_view_observers(window_id, view_id)
1166                        }
1167                        Effect::Focus { window_id, view_id } => {
1168                            self.focus(window_id, view_id);
1169                        }
1170                    }
1171                    self.remove_dropped_entities();
1172                } else {
1173                    self.remove_dropped_entities();
1174                    self.update_windows();
1175
1176                    if self.pending_effects.is_empty() {
1177                        self.flushing_effects = false;
1178                        break;
1179                    }
1180                }
1181            }
1182        }
1183    }
1184
1185    fn update_windows(&mut self) {
1186        let mut invalidations = HashMap::new();
1187        for (window_id, window) in &mut self.cx.windows {
1188            if let Some(invalidation) = window.invalidation.take() {
1189                invalidations.insert(*window_id, invalidation);
1190            }
1191        }
1192
1193        for (window_id, invalidation) in invalidations {
1194            if let Some((presenter, mut window)) =
1195                self.presenters_and_platform_windows.remove(&window_id)
1196            {
1197                {
1198                    let mut presenter = presenter.borrow_mut();
1199                    presenter.invalidate(invalidation, self.as_ref());
1200                    let scene = presenter.build_scene(window.size(), window.scale_factor(), self);
1201                    window.present_scene(scene);
1202                }
1203                self.presenters_and_platform_windows
1204                    .insert(window_id, (presenter, window));
1205            }
1206        }
1207    }
1208
1209    fn emit_event(&mut self, entity_id: usize, payload: Box<dyn Any>) {
1210        if let Some(subscriptions) = self.subscriptions.remove(&entity_id) {
1211            for mut subscription in subscriptions {
1212                let alive = match &mut subscription {
1213                    Subscription::FromModel { model_id, callback } => {
1214                        if let Some(mut model) = self.cx.models.remove(model_id) {
1215                            callback(model.as_any_mut(), payload.as_ref(), self, *model_id);
1216                            self.cx.models.insert(*model_id, model);
1217                            true
1218                        } else {
1219                            false
1220                        }
1221                    }
1222                    Subscription::FromView {
1223                        window_id,
1224                        view_id,
1225                        callback,
1226                    } => {
1227                        if let Some(mut view) = self.cx.views.remove(&(*window_id, *view_id)) {
1228                            callback(
1229                                view.as_any_mut(),
1230                                payload.as_ref(),
1231                                self,
1232                                *window_id,
1233                                *view_id,
1234                            );
1235                            self.cx.views.insert((*window_id, *view_id), view);
1236                            true
1237                        } else {
1238                            false
1239                        }
1240                    }
1241                };
1242
1243                if alive {
1244                    self.subscriptions
1245                        .entry(entity_id)
1246                        .or_default()
1247                        .push(subscription);
1248                }
1249            }
1250        }
1251    }
1252
1253    fn notify_model_observers(&mut self, observed_id: usize) {
1254        if let Some(observations) = self.model_observations.remove(&observed_id) {
1255            if self.cx.models.contains_key(&observed_id) {
1256                for mut observation in observations {
1257                    let alive = match &mut observation {
1258                        ModelObservation::FromModel { model_id, callback } => {
1259                            if let Some(mut model) = self.cx.models.remove(model_id) {
1260                                callback(model.as_any_mut(), observed_id, self, *model_id);
1261                                self.cx.models.insert(*model_id, model);
1262                                true
1263                            } else {
1264                                false
1265                            }
1266                        }
1267                        ModelObservation::FromView {
1268                            window_id,
1269                            view_id,
1270                            callback,
1271                        } => {
1272                            if let Some(mut view) = self.cx.views.remove(&(*window_id, *view_id)) {
1273                                callback(
1274                                    view.as_any_mut(),
1275                                    observed_id,
1276                                    self,
1277                                    *window_id,
1278                                    *view_id,
1279                                );
1280                                self.cx.views.insert((*window_id, *view_id), view);
1281                                true
1282                            } else {
1283                                false
1284                            }
1285                        }
1286                    };
1287
1288                    if alive {
1289                        self.model_observations
1290                            .entry(observed_id)
1291                            .or_default()
1292                            .push(observation);
1293                    }
1294                }
1295            }
1296        }
1297    }
1298
1299    fn notify_view_observers(&mut self, window_id: usize, view_id: usize) {
1300        if let Some(window) = self.cx.windows.get_mut(&window_id) {
1301            window
1302                .invalidation
1303                .get_or_insert_with(Default::default)
1304                .updated
1305                .insert(view_id);
1306        }
1307
1308        if let Some(observations) = self.view_observations.remove(&view_id) {
1309            if self.cx.views.contains_key(&(window_id, view_id)) {
1310                for mut observation in observations {
1311                    let alive = if let Some(mut view) = self
1312                        .cx
1313                        .views
1314                        .remove(&(observation.window_id, observation.view_id))
1315                    {
1316                        (observation.callback)(
1317                            view.as_any_mut(),
1318                            view_id,
1319                            window_id,
1320                            self,
1321                            observation.window_id,
1322                            observation.view_id,
1323                        );
1324                        self.cx
1325                            .views
1326                            .insert((observation.window_id, observation.view_id), view);
1327                        true
1328                    } else {
1329                        false
1330                    };
1331
1332                    if alive {
1333                        self.view_observations
1334                            .entry(view_id)
1335                            .or_default()
1336                            .push(observation);
1337                    }
1338                }
1339            }
1340        }
1341    }
1342
1343    fn focus(&mut self, window_id: usize, focused_id: usize) {
1344        if self
1345            .cx
1346            .windows
1347            .get(&window_id)
1348            .map(|w| w.focused_view_id)
1349            .map_or(false, |cur_focused| cur_focused == focused_id)
1350        {
1351            return;
1352        }
1353
1354        self.pending_flushes += 1;
1355
1356        let blurred_id = self.cx.windows.get_mut(&window_id).map(|window| {
1357            let blurred_id = window.focused_view_id;
1358            window.focused_view_id = focused_id;
1359            blurred_id
1360        });
1361
1362        if let Some(blurred_id) = blurred_id {
1363            if let Some(mut blurred_view) = self.cx.views.remove(&(window_id, blurred_id)) {
1364                blurred_view.on_blur(self, window_id, blurred_id);
1365                self.cx.views.insert((window_id, blurred_id), blurred_view);
1366            }
1367        }
1368
1369        if let Some(mut focused_view) = self.cx.views.remove(&(window_id, focused_id)) {
1370            focused_view.on_focus(self, window_id, focused_id);
1371            self.cx.views.insert((window_id, focused_id), focused_view);
1372        }
1373
1374        self.flush_effects();
1375    }
1376
1377    pub fn spawn<F, Fut, T>(&self, f: F) -> Task<T>
1378    where
1379        F: FnOnce(AsyncAppContext) -> Fut,
1380        Fut: 'static + Future<Output = T>,
1381        T: 'static,
1382    {
1383        let cx = self.to_async();
1384        self.foreground.spawn(f(cx))
1385    }
1386
1387    pub fn to_async(&self) -> AsyncAppContext {
1388        AsyncAppContext(self.weak_self.as_ref().unwrap().upgrade().unwrap())
1389    }
1390
1391    pub fn write_to_clipboard(&self, item: ClipboardItem) {
1392        self.cx.platform.write_to_clipboard(item);
1393    }
1394
1395    pub fn read_from_clipboard(&self) -> Option<ClipboardItem> {
1396        self.cx.platform.read_from_clipboard()
1397    }
1398}
1399
1400impl ReadModel for MutableAppContext {
1401    fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T {
1402        if let Some(model) = self.cx.models.get(&handle.model_id) {
1403            model
1404                .as_any()
1405                .downcast_ref()
1406                .expect("downcast is type safe")
1407        } else {
1408            panic!("circular model reference");
1409        }
1410    }
1411}
1412
1413impl UpdateModel for MutableAppContext {
1414    fn update_model<T, F, S>(&mut self, handle: &ModelHandle<T>, update: F) -> S
1415    where
1416        T: Entity,
1417        F: FnOnce(&mut T, &mut ModelContext<T>) -> S,
1418    {
1419        if let Some(mut model) = self.cx.models.remove(&handle.model_id) {
1420            self.pending_flushes += 1;
1421            let mut cx = ModelContext::new(self, handle.model_id);
1422            let result = update(
1423                model
1424                    .as_any_mut()
1425                    .downcast_mut()
1426                    .expect("downcast is type safe"),
1427                &mut cx,
1428            );
1429            self.cx.models.insert(handle.model_id, model);
1430            self.flush_effects();
1431            result
1432        } else {
1433            panic!("circular model update");
1434        }
1435    }
1436}
1437
1438impl ReadView for MutableAppContext {
1439    fn read_view<T: View>(&self, handle: &ViewHandle<T>) -> &T {
1440        if let Some(view) = self.cx.views.get(&(handle.window_id, handle.view_id)) {
1441            view.as_any().downcast_ref().expect("downcast is type safe")
1442        } else {
1443            panic!("circular view reference");
1444        }
1445    }
1446}
1447
1448impl UpdateView for MutableAppContext {
1449    fn update_view<T, F, S>(&mut self, handle: &ViewHandle<T>, update: F) -> S
1450    where
1451        T: View,
1452        F: FnOnce(&mut T, &mut ViewContext<T>) -> S,
1453    {
1454        self.pending_flushes += 1;
1455        let mut view = self
1456            .cx
1457            .views
1458            .remove(&(handle.window_id, handle.view_id))
1459            .expect("circular view update");
1460
1461        let mut cx = ViewContext::new(self, handle.window_id, handle.view_id);
1462        let result = update(
1463            view.as_any_mut()
1464                .downcast_mut()
1465                .expect("downcast is type safe"),
1466            &mut cx,
1467        );
1468        self.cx
1469            .views
1470            .insert((handle.window_id, handle.view_id), view);
1471        self.flush_effects();
1472        result
1473    }
1474}
1475
1476impl AsRef<AppContext> for MutableAppContext {
1477    fn as_ref(&self) -> &AppContext {
1478        &self.cx
1479    }
1480}
1481
1482impl Deref for MutableAppContext {
1483    type Target = AppContext;
1484
1485    fn deref(&self) -> &Self::Target {
1486        &self.cx
1487    }
1488}
1489
1490pub struct AppContext {
1491    models: HashMap<usize, Box<dyn AnyModel>>,
1492    views: HashMap<(usize, usize), Box<dyn AnyView>>,
1493    windows: HashMap<usize, Window>,
1494    values: RwLock<HashMap<(TypeId, usize), Box<dyn Any>>>,
1495    background: Arc<executor::Background>,
1496    ref_counts: Arc<Mutex<RefCounts>>,
1497    font_cache: Arc<FontCache>,
1498    platform: Arc<dyn Platform>,
1499}
1500
1501impl AppContext {
1502    pub fn root_view_id(&self, window_id: usize) -> Option<usize> {
1503        self.windows
1504            .get(&window_id)
1505            .map(|window| window.root_view.id())
1506    }
1507
1508    pub fn focused_view_id(&self, window_id: usize) -> Option<usize> {
1509        self.windows
1510            .get(&window_id)
1511            .map(|window| window.focused_view_id)
1512    }
1513
1514    pub fn render_view(&self, window_id: usize, view_id: usize) -> Result<ElementBox> {
1515        self.views
1516            .get(&(window_id, view_id))
1517            .map(|v| v.render(window_id, view_id, self))
1518            .ok_or(anyhow!("view not found"))
1519    }
1520
1521    pub fn render_views(&self, window_id: usize) -> HashMap<usize, ElementBox> {
1522        self.views
1523            .iter()
1524            .filter_map(|((win_id, view_id), view)| {
1525                if *win_id == window_id {
1526                    Some((*view_id, view.render(*win_id, *view_id, self)))
1527                } else {
1528                    None
1529                }
1530            })
1531            .collect::<HashMap<_, ElementBox>>()
1532    }
1533
1534    pub fn background(&self) -> &Arc<executor::Background> {
1535        &self.background
1536    }
1537
1538    pub fn font_cache(&self) -> &Arc<FontCache> {
1539        &self.font_cache
1540    }
1541
1542    pub fn platform(&self) -> &Arc<dyn Platform> {
1543        &self.platform
1544    }
1545
1546    pub fn value<Tag: 'static, T: 'static + Default>(&self, id: usize) -> ValueHandle<T> {
1547        let key = (TypeId::of::<Tag>(), id);
1548        self.values
1549            .write()
1550            .entry(key)
1551            .or_insert_with(|| Box::new(T::default()));
1552        ValueHandle::new(TypeId::of::<Tag>(), id, &self.ref_counts)
1553    }
1554}
1555
1556impl ReadModel for AppContext {
1557    fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T {
1558        if let Some(model) = self.models.get(&handle.model_id) {
1559            model
1560                .as_any()
1561                .downcast_ref()
1562                .expect("downcast should be type safe")
1563        } else {
1564            panic!("circular model reference");
1565        }
1566    }
1567}
1568
1569impl ReadView for AppContext {
1570    fn read_view<T: View>(&self, handle: &ViewHandle<T>) -> &T {
1571        if let Some(view) = self.views.get(&(handle.window_id, handle.view_id)) {
1572            view.as_any()
1573                .downcast_ref()
1574                .expect("downcast should be type safe")
1575        } else {
1576            panic!("circular view reference");
1577        }
1578    }
1579}
1580
1581struct Window {
1582    root_view: AnyViewHandle,
1583    focused_view_id: usize,
1584    invalidation: Option<WindowInvalidation>,
1585}
1586
1587#[derive(Default, Clone)]
1588pub struct WindowInvalidation {
1589    pub updated: HashSet<usize>,
1590    pub removed: Vec<usize>,
1591}
1592
1593pub enum Effect {
1594    Event {
1595        entity_id: usize,
1596        payload: Box<dyn Any>,
1597    },
1598    ModelNotification {
1599        model_id: usize,
1600    },
1601    ViewNotification {
1602        window_id: usize,
1603        view_id: usize,
1604    },
1605    Focus {
1606        window_id: usize,
1607        view_id: usize,
1608    },
1609}
1610
1611impl Debug for Effect {
1612    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1613        match self {
1614            Effect::Event { entity_id, .. } => f
1615                .debug_struct("Effect::Event")
1616                .field("entity_id", entity_id)
1617                .finish(),
1618            Effect::ModelNotification { model_id } => f
1619                .debug_struct("Effect::ModelNotification")
1620                .field("model_id", model_id)
1621                .finish(),
1622            Effect::ViewNotification { window_id, view_id } => f
1623                .debug_struct("Effect::ViewNotification")
1624                .field("window_id", window_id)
1625                .field("view_id", view_id)
1626                .finish(),
1627            Effect::Focus { window_id, view_id } => f
1628                .debug_struct("Effect::Focus")
1629                .field("window_id", window_id)
1630                .field("view_id", view_id)
1631                .finish(),
1632        }
1633    }
1634}
1635
1636pub trait AnyModel: Send + Sync {
1637    fn as_any(&self) -> &dyn Any;
1638    fn as_any_mut(&mut self) -> &mut dyn Any;
1639    fn release(&mut self, cx: &mut MutableAppContext);
1640}
1641
1642impl<T> AnyModel for T
1643where
1644    T: Entity,
1645{
1646    fn as_any(&self) -> &dyn Any {
1647        self
1648    }
1649
1650    fn as_any_mut(&mut self) -> &mut dyn Any {
1651        self
1652    }
1653
1654    fn release(&mut self, cx: &mut MutableAppContext) {
1655        self.release(cx);
1656    }
1657}
1658
1659pub trait AnyView: Send + Sync {
1660    fn as_any(&self) -> &dyn Any;
1661    fn as_any_mut(&mut self) -> &mut dyn Any;
1662    fn release(&mut self, cx: &mut MutableAppContext);
1663    fn ui_name(&self) -> &'static str;
1664    fn render<'a>(&self, window_id: usize, view_id: usize, cx: &AppContext) -> ElementBox;
1665    fn on_focus(&mut self, cx: &mut MutableAppContext, window_id: usize, view_id: usize);
1666    fn on_blur(&mut self, cx: &mut MutableAppContext, window_id: usize, view_id: usize);
1667    fn keymap_context(&self, cx: &AppContext) -> keymap::Context;
1668}
1669
1670impl<T> AnyView for T
1671where
1672    T: View,
1673{
1674    fn as_any(&self) -> &dyn Any {
1675        self
1676    }
1677
1678    fn as_any_mut(&mut self) -> &mut dyn Any {
1679        self
1680    }
1681
1682    fn release(&mut self, cx: &mut MutableAppContext) {
1683        self.release(cx);
1684    }
1685
1686    fn ui_name(&self) -> &'static str {
1687        T::ui_name()
1688    }
1689
1690    fn render<'a>(&self, window_id: usize, view_id: usize, cx: &AppContext) -> ElementBox {
1691        View::render(
1692            self,
1693            &RenderContext {
1694                window_id,
1695                view_id,
1696                app: cx,
1697                view_type: PhantomData::<T>,
1698            },
1699        )
1700    }
1701
1702    fn on_focus(&mut self, cx: &mut MutableAppContext, window_id: usize, view_id: usize) {
1703        let mut cx = ViewContext::new(cx, window_id, view_id);
1704        View::on_focus(self, &mut cx);
1705    }
1706
1707    fn on_blur(&mut self, cx: &mut MutableAppContext, window_id: usize, view_id: usize) {
1708        let mut cx = ViewContext::new(cx, window_id, view_id);
1709        View::on_blur(self, &mut cx);
1710    }
1711
1712    fn keymap_context(&self, cx: &AppContext) -> keymap::Context {
1713        View::keymap_context(self, cx)
1714    }
1715}
1716
1717pub struct ModelContext<'a, T: ?Sized> {
1718    app: &'a mut MutableAppContext,
1719    model_id: usize,
1720    model_type: PhantomData<T>,
1721    halt_stream: bool,
1722}
1723
1724impl<'a, T: Entity> ModelContext<'a, T> {
1725    fn new(app: &'a mut MutableAppContext, model_id: usize) -> Self {
1726        Self {
1727            app,
1728            model_id,
1729            model_type: PhantomData,
1730            halt_stream: false,
1731        }
1732    }
1733
1734    pub fn background(&self) -> &Arc<executor::Background> {
1735        &self.app.cx.background
1736    }
1737
1738    pub fn halt_stream(&mut self) {
1739        self.halt_stream = true;
1740    }
1741
1742    pub fn model_id(&self) -> usize {
1743        self.model_id
1744    }
1745
1746    pub fn add_model<S, F>(&mut self, build_model: F) -> ModelHandle<S>
1747    where
1748        S: Entity,
1749        F: FnOnce(&mut ModelContext<S>) -> S,
1750    {
1751        self.app.add_model(build_model)
1752    }
1753
1754    pub fn subscribe<S: Entity, F>(&mut self, handle: &ModelHandle<S>, mut callback: F)
1755    where
1756        S::Event: 'static,
1757        F: 'static + FnMut(&mut T, &S::Event, &mut ModelContext<T>),
1758    {
1759        self.app
1760            .subscriptions
1761            .entry(handle.model_id)
1762            .or_default()
1763            .push(Subscription::FromModel {
1764                model_id: self.model_id,
1765                callback: Box::new(move |model, payload, app, model_id| {
1766                    let model = model.downcast_mut().expect("downcast is type safe");
1767                    let payload = payload.downcast_ref().expect("downcast is type safe");
1768                    let mut cx = ModelContext::new(app, model_id);
1769                    callback(model, payload, &mut cx);
1770                }),
1771            });
1772    }
1773
1774    pub fn emit(&mut self, payload: T::Event) {
1775        self.app.pending_effects.push_back(Effect::Event {
1776            entity_id: self.model_id,
1777            payload: Box::new(payload),
1778        });
1779    }
1780
1781    pub fn observe<S, F>(&mut self, handle: &ModelHandle<S>, mut callback: F)
1782    where
1783        S: Entity,
1784        F: 'static + FnMut(&mut T, ModelHandle<S>, &mut ModelContext<T>),
1785    {
1786        self.app
1787            .model_observations
1788            .entry(handle.model_id)
1789            .or_default()
1790            .push(ModelObservation::FromModel {
1791                model_id: self.model_id,
1792                callback: Box::new(move |model, observed_id, app, model_id| {
1793                    let model = model.downcast_mut().expect("downcast is type safe");
1794                    let observed = ModelHandle::new(observed_id, &app.cx.ref_counts);
1795                    let mut cx = ModelContext::new(app, model_id);
1796                    callback(model, observed, &mut cx);
1797                }),
1798            });
1799    }
1800
1801    pub fn notify(&mut self) {
1802        self.app
1803            .pending_effects
1804            .push_back(Effect::ModelNotification {
1805                model_id: self.model_id,
1806            });
1807    }
1808
1809    pub fn handle(&self) -> ModelHandle<T> {
1810        ModelHandle::new(self.model_id, &self.app.cx.ref_counts)
1811    }
1812
1813    pub fn spawn<F, Fut, S>(&self, f: F) -> Task<S>
1814    where
1815        F: FnOnce(ModelHandle<T>, AsyncAppContext) -> Fut,
1816        Fut: 'static + Future<Output = S>,
1817        S: 'static,
1818    {
1819        let handle = self.handle();
1820        self.app.spawn(|cx| f(handle, cx))
1821    }
1822
1823    pub fn spawn_weak<F, Fut, S>(&self, f: F) -> Task<S>
1824    where
1825        F: FnOnce(WeakModelHandle<T>, AsyncAppContext) -> Fut,
1826        Fut: 'static + Future<Output = S>,
1827        S: 'static,
1828    {
1829        let handle = self.handle().downgrade();
1830        self.app.spawn(|cx| f(handle, cx))
1831    }
1832}
1833
1834impl<M> AsRef<AppContext> for ModelContext<'_, M> {
1835    fn as_ref(&self) -> &AppContext {
1836        &self.app.cx
1837    }
1838}
1839
1840impl<M> AsMut<MutableAppContext> for ModelContext<'_, M> {
1841    fn as_mut(&mut self) -> &mut MutableAppContext {
1842        self.app
1843    }
1844}
1845
1846impl<M> ReadModel for ModelContext<'_, M> {
1847    fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T {
1848        self.app.read_model(handle)
1849    }
1850}
1851
1852impl<M> UpdateModel for ModelContext<'_, M> {
1853    fn update_model<T, F, S>(&mut self, handle: &ModelHandle<T>, update: F) -> S
1854    where
1855        T: Entity,
1856        F: FnOnce(&mut T, &mut ModelContext<T>) -> S,
1857    {
1858        self.app.update_model(handle, update)
1859    }
1860}
1861
1862impl<M> Deref for ModelContext<'_, M> {
1863    type Target = MutableAppContext;
1864
1865    fn deref(&self) -> &Self::Target {
1866        &self.app
1867    }
1868}
1869
1870impl<M> DerefMut for ModelContext<'_, M> {
1871    fn deref_mut(&mut self) -> &mut Self::Target {
1872        &mut self.app
1873    }
1874}
1875
1876pub struct ViewContext<'a, T: ?Sized> {
1877    app: &'a mut MutableAppContext,
1878    window_id: usize,
1879    view_id: usize,
1880    view_type: PhantomData<T>,
1881    halt_action_dispatch: bool,
1882}
1883
1884impl<'a, T: View> ViewContext<'a, T> {
1885    fn new(app: &'a mut MutableAppContext, window_id: usize, view_id: usize) -> Self {
1886        Self {
1887            app,
1888            window_id,
1889            view_id,
1890            view_type: PhantomData,
1891            halt_action_dispatch: true,
1892        }
1893    }
1894
1895    pub fn handle(&self) -> ViewHandle<T> {
1896        ViewHandle::new(self.window_id, self.view_id, &self.app.cx.ref_counts)
1897    }
1898
1899    pub fn window_id(&self) -> usize {
1900        self.window_id
1901    }
1902
1903    pub fn view_id(&self) -> usize {
1904        self.view_id
1905    }
1906
1907    pub fn foreground(&self) -> &Rc<executor::Foreground> {
1908        self.app.foreground()
1909    }
1910
1911    pub fn background_executor(&self) -> &Arc<executor::Background> {
1912        &self.app.cx.background
1913    }
1914
1915    pub fn platform(&self) -> Arc<dyn Platform> {
1916        self.app.platform()
1917    }
1918
1919    pub fn prompt<F>(&self, level: PromptLevel, msg: &str, answers: &[&str], done_fn: F)
1920    where
1921        F: 'static + FnOnce(usize, &mut MutableAppContext),
1922    {
1923        self.app
1924            .prompt(self.window_id, level, msg, answers, done_fn)
1925    }
1926
1927    pub fn prompt_for_paths<F>(&self, options: PathPromptOptions, done_fn: F)
1928    where
1929        F: 'static + FnOnce(Option<Vec<PathBuf>>, &mut MutableAppContext),
1930    {
1931        self.app.prompt_for_paths(options, done_fn)
1932    }
1933
1934    pub fn prompt_for_new_path<F>(&self, directory: &Path, done_fn: F)
1935    where
1936        F: 'static + FnOnce(Option<PathBuf>, &mut MutableAppContext),
1937    {
1938        self.app.prompt_for_new_path(directory, done_fn)
1939    }
1940
1941    pub fn debug_elements(&self) -> crate::json::Value {
1942        self.app.debug_elements(self.window_id).unwrap()
1943    }
1944
1945    pub fn focus<S>(&mut self, handle: S)
1946    where
1947        S: Into<AnyViewHandle>,
1948    {
1949        let handle = handle.into();
1950        self.app.pending_effects.push_back(Effect::Focus {
1951            window_id: handle.window_id,
1952            view_id: handle.view_id,
1953        });
1954    }
1955
1956    pub fn focus_self(&mut self) {
1957        self.app.pending_effects.push_back(Effect::Focus {
1958            window_id: self.window_id,
1959            view_id: self.view_id,
1960        });
1961    }
1962
1963    pub fn add_model<S, F>(&mut self, build_model: F) -> ModelHandle<S>
1964    where
1965        S: Entity,
1966        F: FnOnce(&mut ModelContext<S>) -> S,
1967    {
1968        self.app.add_model(build_model)
1969    }
1970
1971    pub fn add_view<S, F>(&mut self, build_view: F) -> ViewHandle<S>
1972    where
1973        S: View,
1974        F: FnOnce(&mut ViewContext<S>) -> S,
1975    {
1976        self.app.add_view(self.window_id, build_view)
1977    }
1978
1979    pub fn add_option_view<S, F>(&mut self, build_view: F) -> Option<ViewHandle<S>>
1980    where
1981        S: View,
1982        F: FnOnce(&mut ViewContext<S>) -> Option<S>,
1983    {
1984        self.app.add_option_view(self.window_id, build_view)
1985    }
1986
1987    pub fn subscribe_to_model<E, F>(&mut self, handle: &ModelHandle<E>, mut callback: F)
1988    where
1989        E: Entity,
1990        E::Event: 'static,
1991        F: 'static + FnMut(&mut T, ModelHandle<E>, &E::Event, &mut ViewContext<T>),
1992    {
1993        let emitter_handle = handle.downgrade();
1994        self.subscribe(handle, move |model, payload, cx| {
1995            if let Some(emitter_handle) = emitter_handle.upgrade(cx.as_ref()) {
1996                callback(model, emitter_handle, payload, cx);
1997            }
1998        });
1999    }
2000
2001    pub fn subscribe_to_view<V, F>(&mut self, handle: &ViewHandle<V>, mut callback: F)
2002    where
2003        V: View,
2004        V::Event: 'static,
2005        F: 'static + FnMut(&mut T, ViewHandle<V>, &V::Event, &mut ViewContext<T>),
2006    {
2007        let emitter_handle = handle.downgrade();
2008        self.subscribe(handle, move |view, payload, cx| {
2009            if let Some(emitter_handle) = emitter_handle.upgrade(cx.as_ref()) {
2010                callback(view, emitter_handle, payload, cx);
2011            }
2012        });
2013    }
2014
2015    pub fn subscribe<E, F>(&mut self, handle: &impl Handle<E>, mut callback: F)
2016    where
2017        E: Entity,
2018        E::Event: 'static,
2019        F: 'static + FnMut(&mut T, &E::Event, &mut ViewContext<T>),
2020    {
2021        self.app
2022            .subscriptions
2023            .entry(handle.id())
2024            .or_default()
2025            .push(Subscription::FromView {
2026                window_id: self.window_id,
2027                view_id: self.view_id,
2028                callback: Box::new(move |entity, payload, app, window_id, view_id| {
2029                    let entity = entity.downcast_mut().expect("downcast is type safe");
2030                    let payload = payload.downcast_ref().expect("downcast is type safe");
2031                    let mut cx = ViewContext::new(app, window_id, view_id);
2032                    callback(entity, payload, &mut cx);
2033                }),
2034            });
2035    }
2036
2037    pub fn emit(&mut self, payload: T::Event) {
2038        self.app.pending_effects.push_back(Effect::Event {
2039            entity_id: self.view_id,
2040            payload: Box::new(payload),
2041        });
2042    }
2043
2044    pub fn observe_model<S, F>(&mut self, handle: &ModelHandle<S>, mut callback: F)
2045    where
2046        S: Entity,
2047        F: 'static + FnMut(&mut T, ModelHandle<S>, &mut ViewContext<T>),
2048    {
2049        self.app
2050            .model_observations
2051            .entry(handle.id())
2052            .or_default()
2053            .push(ModelObservation::FromView {
2054                window_id: self.window_id,
2055                view_id: self.view_id,
2056                callback: Box::new(move |view, observed_id, app, window_id, view_id| {
2057                    let view = view.downcast_mut().expect("downcast is type safe");
2058                    let observed = ModelHandle::new(observed_id, &app.cx.ref_counts);
2059                    let mut cx = ViewContext::new(app, window_id, view_id);
2060                    callback(view, observed, &mut cx);
2061                }),
2062            });
2063    }
2064
2065    pub fn observe_view<S, F>(&mut self, handle: &ViewHandle<S>, mut callback: F)
2066    where
2067        S: View,
2068        F: 'static + FnMut(&mut T, ViewHandle<S>, &mut ViewContext<T>),
2069    {
2070        self.app
2071            .view_observations
2072            .entry(handle.id())
2073            .or_default()
2074            .push(ViewObservation {
2075                window_id: self.window_id,
2076                view_id: self.view_id,
2077                callback: Box::new(
2078                    move |view,
2079                          observed_view_id,
2080                          observed_window_id,
2081                          app,
2082                          observing_window_id,
2083                          observing_view_id| {
2084                        let view = view.downcast_mut().expect("downcast is type safe");
2085                        let observed_handle = ViewHandle::new(
2086                            observed_view_id,
2087                            observed_window_id,
2088                            &app.cx.ref_counts,
2089                        );
2090                        let mut cx = ViewContext::new(app, observing_window_id, observing_view_id);
2091                        callback(view, observed_handle, &mut cx);
2092                    },
2093                ),
2094            });
2095    }
2096
2097    pub fn notify(&mut self) {
2098        self.app.notify_view(self.window_id, self.view_id);
2099    }
2100
2101    pub fn notify_all(&mut self) {
2102        self.app.notify_all_views();
2103    }
2104
2105    pub fn propagate_action(&mut self) {
2106        self.halt_action_dispatch = false;
2107    }
2108
2109    pub fn spawn<F, Fut, S>(&self, f: F) -> Task<S>
2110    where
2111        F: FnOnce(ViewHandle<T>, AsyncAppContext) -> Fut,
2112        Fut: 'static + Future<Output = S>,
2113        S: 'static,
2114    {
2115        let handle = self.handle();
2116        self.app.spawn(|cx| f(handle, cx))
2117    }
2118}
2119
2120pub struct RenderContext<'a, T: View> {
2121    pub app: &'a AppContext,
2122    window_id: usize,
2123    view_id: usize,
2124    view_type: PhantomData<T>,
2125}
2126
2127impl<'a, T: View> RenderContext<'a, T> {
2128    pub fn handle(&self) -> WeakViewHandle<T> {
2129        WeakViewHandle::new(self.window_id, self.view_id)
2130    }
2131}
2132
2133impl AsRef<AppContext> for &AppContext {
2134    fn as_ref(&self) -> &AppContext {
2135        self
2136    }
2137}
2138
2139impl<V: View> Deref for RenderContext<'_, V> {
2140    type Target = AppContext;
2141
2142    fn deref(&self) -> &Self::Target {
2143        &self.app
2144    }
2145}
2146
2147impl<M> AsRef<AppContext> for ViewContext<'_, M> {
2148    fn as_ref(&self) -> &AppContext {
2149        &self.app.cx
2150    }
2151}
2152
2153impl<M> Deref for ViewContext<'_, M> {
2154    type Target = MutableAppContext;
2155
2156    fn deref(&self) -> &Self::Target {
2157        &self.app
2158    }
2159}
2160
2161impl<M> DerefMut for ViewContext<'_, M> {
2162    fn deref_mut(&mut self) -> &mut Self::Target {
2163        &mut self.app
2164    }
2165}
2166
2167impl<M> AsMut<MutableAppContext> for ViewContext<'_, M> {
2168    fn as_mut(&mut self) -> &mut MutableAppContext {
2169        self.app
2170    }
2171}
2172
2173impl<V> ReadModel for ViewContext<'_, V> {
2174    fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T {
2175        self.app.read_model(handle)
2176    }
2177}
2178
2179impl<V: View> UpdateModel for ViewContext<'_, V> {
2180    fn update_model<T, F, S>(&mut self, handle: &ModelHandle<T>, update: F) -> S
2181    where
2182        T: Entity,
2183        F: FnOnce(&mut T, &mut ModelContext<T>) -> S,
2184    {
2185        self.app.update_model(handle, update)
2186    }
2187}
2188
2189impl<V: View> ReadView for ViewContext<'_, V> {
2190    fn read_view<T: View>(&self, handle: &ViewHandle<T>) -> &T {
2191        self.app.read_view(handle)
2192    }
2193}
2194
2195impl<V: View> UpdateView for ViewContext<'_, V> {
2196    fn update_view<T, F, S>(&mut self, handle: &ViewHandle<T>, update: F) -> S
2197    where
2198        T: View,
2199        F: FnOnce(&mut T, &mut ViewContext<T>) -> S,
2200    {
2201        self.app.update_view(handle, update)
2202    }
2203}
2204
2205pub trait Handle<T> {
2206    fn id(&self) -> usize;
2207    fn location(&self) -> EntityLocation;
2208}
2209
2210#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash)]
2211pub enum EntityLocation {
2212    Model(usize),
2213    View(usize, usize),
2214}
2215
2216pub struct ModelHandle<T> {
2217    model_id: usize,
2218    model_type: PhantomData<T>,
2219    ref_counts: Arc<Mutex<RefCounts>>,
2220}
2221
2222impl<T: Entity> ModelHandle<T> {
2223    fn new(model_id: usize, ref_counts: &Arc<Mutex<RefCounts>>) -> Self {
2224        ref_counts.lock().inc_model(model_id);
2225        Self {
2226            model_id,
2227            model_type: PhantomData,
2228            ref_counts: ref_counts.clone(),
2229        }
2230    }
2231
2232    pub fn downgrade(&self) -> WeakModelHandle<T> {
2233        WeakModelHandle::new(self.model_id)
2234    }
2235
2236    pub fn id(&self) -> usize {
2237        self.model_id
2238    }
2239
2240    pub fn read<'a, C: ReadModel>(&self, cx: &'a C) -> &'a T {
2241        cx.read_model(self)
2242    }
2243
2244    pub fn read_with<'a, C, F, S>(&self, cx: &C, read: F) -> S
2245    where
2246        C: ReadModelWith,
2247        F: FnOnce(&T, &AppContext) -> S,
2248    {
2249        cx.read_model_with(self, read)
2250    }
2251
2252    pub fn update<C, F, S>(&self, cx: &mut C, update: F) -> S
2253    where
2254        C: UpdateModel,
2255        F: FnOnce(&mut T, &mut ModelContext<T>) -> S,
2256    {
2257        cx.update_model(self, update)
2258    }
2259
2260    pub fn condition(
2261        &self,
2262        cx: &TestAppContext,
2263        mut predicate: impl FnMut(&T, &AppContext) -> bool,
2264    ) -> impl Future<Output = ()> {
2265        let (tx, mut rx) = mpsc::channel(1024);
2266
2267        let mut cx = cx.cx.borrow_mut();
2268        self.update(&mut *cx, |_, cx| {
2269            cx.observe(self, {
2270                let mut tx = tx.clone();
2271                move |_, _, _| {
2272                    tx.blocking_send(()).ok();
2273                }
2274            });
2275            cx.subscribe(self, {
2276                let mut tx = tx.clone();
2277                move |_, _, _| {
2278                    tx.blocking_send(()).ok();
2279                }
2280            })
2281        });
2282
2283        let cx = cx.weak_self.as_ref().unwrap().upgrade().unwrap();
2284        let handle = self.downgrade();
2285        let duration = if std::env::var("CI").is_ok() {
2286            Duration::from_secs(5)
2287        } else {
2288            Duration::from_secs(1)
2289        };
2290
2291        async move {
2292            timeout(duration, async move {
2293                loop {
2294                    {
2295                        let cx = cx.borrow();
2296                        let cx = cx.as_ref();
2297                        if predicate(
2298                            handle
2299                                .upgrade(cx)
2300                                .expect("model dropped with pending condition")
2301                                .read(cx),
2302                            cx,
2303                        ) {
2304                            break;
2305                        }
2306                    }
2307
2308                    rx.recv()
2309                        .await
2310                        .expect("model dropped with pending condition");
2311                }
2312            })
2313            .await
2314            .expect("condition timed out");
2315        }
2316    }
2317}
2318
2319impl<T> Clone for ModelHandle<T> {
2320    fn clone(&self) -> Self {
2321        self.ref_counts.lock().inc_model(self.model_id);
2322        Self {
2323            model_id: self.model_id,
2324            model_type: PhantomData,
2325            ref_counts: self.ref_counts.clone(),
2326        }
2327    }
2328}
2329
2330impl<T> PartialEq for ModelHandle<T> {
2331    fn eq(&self, other: &Self) -> bool {
2332        self.model_id == other.model_id
2333    }
2334}
2335
2336impl<T> Eq for ModelHandle<T> {}
2337
2338impl<T> Hash for ModelHandle<T> {
2339    fn hash<H: Hasher>(&self, state: &mut H) {
2340        self.model_id.hash(state);
2341    }
2342}
2343
2344impl<T> std::borrow::Borrow<usize> for ModelHandle<T> {
2345    fn borrow(&self) -> &usize {
2346        &self.model_id
2347    }
2348}
2349
2350impl<T> Debug for ModelHandle<T> {
2351    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2352        f.debug_tuple(&format!("ModelHandle<{}>", type_name::<T>()))
2353            .field(&self.model_id)
2354            .finish()
2355    }
2356}
2357
2358unsafe impl<T> Send for ModelHandle<T> {}
2359unsafe impl<T> Sync for ModelHandle<T> {}
2360
2361impl<T> Drop for ModelHandle<T> {
2362    fn drop(&mut self) {
2363        self.ref_counts.lock().dec_model(self.model_id);
2364    }
2365}
2366
2367impl<T> Handle<T> for ModelHandle<T> {
2368    fn id(&self) -> usize {
2369        self.model_id
2370    }
2371
2372    fn location(&self) -> EntityLocation {
2373        EntityLocation::Model(self.model_id)
2374    }
2375}
2376
2377pub struct WeakModelHandle<T> {
2378    model_id: usize,
2379    model_type: PhantomData<T>,
2380}
2381
2382impl<T: Entity> WeakModelHandle<T> {
2383    fn new(model_id: usize) -> Self {
2384        Self {
2385            model_id,
2386            model_type: PhantomData,
2387        }
2388    }
2389
2390    pub fn upgrade(&self, cx: impl AsRef<AppContext>) -> Option<ModelHandle<T>> {
2391        let cx = cx.as_ref();
2392        if cx.models.contains_key(&self.model_id) {
2393            Some(ModelHandle::new(self.model_id, &cx.ref_counts))
2394        } else {
2395            None
2396        }
2397    }
2398}
2399
2400impl<T> Hash for WeakModelHandle<T> {
2401    fn hash<H: Hasher>(&self, state: &mut H) {
2402        self.model_id.hash(state)
2403    }
2404}
2405
2406impl<T> PartialEq for WeakModelHandle<T> {
2407    fn eq(&self, other: &Self) -> bool {
2408        self.model_id == other.model_id
2409    }
2410}
2411
2412impl<T> Eq for WeakModelHandle<T> {}
2413
2414impl<T> Clone for WeakModelHandle<T> {
2415    fn clone(&self) -> Self {
2416        Self {
2417            model_id: self.model_id,
2418            model_type: PhantomData,
2419        }
2420    }
2421}
2422
2423pub struct ViewHandle<T> {
2424    window_id: usize,
2425    view_id: usize,
2426    view_type: PhantomData<T>,
2427    ref_counts: Arc<Mutex<RefCounts>>,
2428}
2429
2430impl<T: View> ViewHandle<T> {
2431    fn new(window_id: usize, view_id: usize, ref_counts: &Arc<Mutex<RefCounts>>) -> Self {
2432        ref_counts.lock().inc_view(window_id, view_id);
2433        Self {
2434            window_id,
2435            view_id,
2436            view_type: PhantomData,
2437            ref_counts: ref_counts.clone(),
2438        }
2439    }
2440
2441    pub fn downgrade(&self) -> WeakViewHandle<T> {
2442        WeakViewHandle::new(self.window_id, self.view_id)
2443    }
2444
2445    pub fn window_id(&self) -> usize {
2446        self.window_id
2447    }
2448
2449    pub fn id(&self) -> usize {
2450        self.view_id
2451    }
2452
2453    pub fn read<'a, C: ReadView>(&self, cx: &'a C) -> &'a T {
2454        cx.read_view(self)
2455    }
2456
2457    pub fn read_with<C, F, S>(&self, cx: &C, read: F) -> S
2458    where
2459        C: ReadViewWith,
2460        F: FnOnce(&T, &AppContext) -> S,
2461    {
2462        cx.read_view_with(self, read)
2463    }
2464
2465    pub fn update<C, F, S>(&self, cx: &mut C, update: F) -> S
2466    where
2467        C: UpdateView,
2468        F: FnOnce(&mut T, &mut ViewContext<T>) -> S,
2469    {
2470        cx.update_view(self, update)
2471    }
2472
2473    pub fn is_focused(&self, cx: &AppContext) -> bool {
2474        cx.focused_view_id(self.window_id)
2475            .map_or(false, |focused_id| focused_id == self.view_id)
2476    }
2477
2478    pub fn condition(
2479        &self,
2480        cx: &TestAppContext,
2481        mut predicate: impl FnMut(&T, &AppContext) -> bool,
2482    ) -> impl Future<Output = ()> {
2483        let (tx, mut rx) = mpsc::channel(1024);
2484
2485        let mut cx = cx.cx.borrow_mut();
2486        self.update(&mut *cx, |_, cx| {
2487            cx.observe_view(self, {
2488                let mut tx = tx.clone();
2489                move |_, _, _| {
2490                    tx.blocking_send(()).ok();
2491                }
2492            });
2493
2494            cx.subscribe(self, {
2495                let mut tx = tx.clone();
2496                move |_, _, _| {
2497                    tx.blocking_send(()).ok();
2498                }
2499            })
2500        });
2501
2502        let cx = cx.weak_self.as_ref().unwrap().upgrade().unwrap();
2503        let handle = self.downgrade();
2504        let duration = if std::env::var("CI").is_ok() {
2505            Duration::from_secs(2)
2506        } else {
2507            Duration::from_millis(500)
2508        };
2509
2510        async move {
2511            timeout(duration, async move {
2512                loop {
2513                    {
2514                        let cx = cx.borrow();
2515                        let cx = cx.as_ref();
2516                        if predicate(
2517                            handle
2518                                .upgrade(cx)
2519                                .expect("view dropped with pending condition")
2520                                .read(cx),
2521                            cx,
2522                        ) {
2523                            break;
2524                        }
2525                    }
2526
2527                    rx.recv()
2528                        .await
2529                        .expect("view dropped with pending condition");
2530                }
2531            })
2532            .await
2533            .expect("condition timed out");
2534        }
2535    }
2536}
2537
2538impl<T> Clone for ViewHandle<T> {
2539    fn clone(&self) -> Self {
2540        self.ref_counts
2541            .lock()
2542            .inc_view(self.window_id, self.view_id);
2543        Self {
2544            window_id: self.window_id,
2545            view_id: self.view_id,
2546            view_type: PhantomData,
2547            ref_counts: self.ref_counts.clone(),
2548        }
2549    }
2550}
2551
2552impl<T> PartialEq for ViewHandle<T> {
2553    fn eq(&self, other: &Self) -> bool {
2554        self.window_id == other.window_id && self.view_id == other.view_id
2555    }
2556}
2557
2558impl<T> Eq for ViewHandle<T> {}
2559
2560impl<T> Debug for ViewHandle<T> {
2561    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2562        f.debug_struct(&format!("ViewHandle<{}>", type_name::<T>()))
2563            .field("window_id", &self.window_id)
2564            .field("view_id", &self.view_id)
2565            .finish()
2566    }
2567}
2568
2569impl<T> Drop for ViewHandle<T> {
2570    fn drop(&mut self) {
2571        self.ref_counts
2572            .lock()
2573            .dec_view(self.window_id, self.view_id);
2574    }
2575}
2576
2577impl<T> Handle<T> for ViewHandle<T> {
2578    fn id(&self) -> usize {
2579        self.view_id
2580    }
2581
2582    fn location(&self) -> EntityLocation {
2583        EntityLocation::View(self.window_id, self.view_id)
2584    }
2585}
2586
2587pub struct AnyViewHandle {
2588    window_id: usize,
2589    view_id: usize,
2590    view_type: TypeId,
2591    ref_counts: Arc<Mutex<RefCounts>>,
2592}
2593
2594impl AnyViewHandle {
2595    pub fn id(&self) -> usize {
2596        self.view_id
2597    }
2598
2599    pub fn is<T: 'static>(&self) -> bool {
2600        TypeId::of::<T>() == self.view_type
2601    }
2602
2603    pub fn downcast<T: View>(self) -> Option<ViewHandle<T>> {
2604        if self.is::<T>() {
2605            let result = Some(ViewHandle {
2606                window_id: self.window_id,
2607                view_id: self.view_id,
2608                ref_counts: self.ref_counts.clone(),
2609                view_type: PhantomData,
2610            });
2611            unsafe {
2612                Arc::decrement_strong_count(&self.ref_counts);
2613            }
2614            std::mem::forget(self);
2615            result
2616        } else {
2617            None
2618        }
2619    }
2620}
2621
2622impl Clone for AnyViewHandle {
2623    fn clone(&self) -> Self {
2624        self.ref_counts
2625            .lock()
2626            .inc_view(self.window_id, self.view_id);
2627        Self {
2628            window_id: self.window_id,
2629            view_id: self.view_id,
2630            view_type: self.view_type,
2631            ref_counts: self.ref_counts.clone(),
2632        }
2633    }
2634}
2635
2636impl<T: View> From<&ViewHandle<T>> for AnyViewHandle {
2637    fn from(handle: &ViewHandle<T>) -> Self {
2638        handle
2639            .ref_counts
2640            .lock()
2641            .inc_view(handle.window_id, handle.view_id);
2642        AnyViewHandle {
2643            window_id: handle.window_id,
2644            view_id: handle.view_id,
2645            view_type: TypeId::of::<T>(),
2646            ref_counts: handle.ref_counts.clone(),
2647        }
2648    }
2649}
2650
2651impl<T: View> From<ViewHandle<T>> for AnyViewHandle {
2652    fn from(handle: ViewHandle<T>) -> Self {
2653        let any_handle = AnyViewHandle {
2654            window_id: handle.window_id,
2655            view_id: handle.view_id,
2656            view_type: TypeId::of::<T>(),
2657            ref_counts: handle.ref_counts.clone(),
2658        };
2659        unsafe {
2660            Arc::decrement_strong_count(&handle.ref_counts);
2661        }
2662        std::mem::forget(handle);
2663        any_handle
2664    }
2665}
2666
2667impl Drop for AnyViewHandle {
2668    fn drop(&mut self) {
2669        self.ref_counts
2670            .lock()
2671            .dec_view(self.window_id, self.view_id);
2672    }
2673}
2674
2675pub struct AnyModelHandle {
2676    model_id: usize,
2677    ref_counts: Arc<Mutex<RefCounts>>,
2678}
2679
2680impl<T: Entity> From<ModelHandle<T>> for AnyModelHandle {
2681    fn from(handle: ModelHandle<T>) -> Self {
2682        handle.ref_counts.lock().inc_model(handle.model_id);
2683        Self {
2684            model_id: handle.model_id,
2685            ref_counts: handle.ref_counts.clone(),
2686        }
2687    }
2688}
2689
2690impl Drop for AnyModelHandle {
2691    fn drop(&mut self) {
2692        self.ref_counts.lock().dec_model(self.model_id);
2693    }
2694}
2695pub struct WeakViewHandle<T> {
2696    window_id: usize,
2697    view_id: usize,
2698    view_type: PhantomData<T>,
2699}
2700
2701impl<T: View> WeakViewHandle<T> {
2702    fn new(window_id: usize, view_id: usize) -> Self {
2703        Self {
2704            window_id,
2705            view_id,
2706            view_type: PhantomData,
2707        }
2708    }
2709
2710    pub fn upgrade(&self, cx: &AppContext) -> Option<ViewHandle<T>> {
2711        if cx.ref_counts.lock().is_entity_alive(self.view_id) {
2712            Some(ViewHandle::new(
2713                self.window_id,
2714                self.view_id,
2715                &cx.ref_counts,
2716            ))
2717        } else {
2718            None
2719        }
2720    }
2721}
2722
2723impl<T> Clone for WeakViewHandle<T> {
2724    fn clone(&self) -> Self {
2725        Self {
2726            window_id: self.window_id,
2727            view_id: self.view_id,
2728            view_type: PhantomData,
2729        }
2730    }
2731}
2732
2733pub struct ValueHandle<T> {
2734    value_type: PhantomData<T>,
2735    tag_type_id: TypeId,
2736    id: usize,
2737    ref_counts: Weak<Mutex<RefCounts>>,
2738}
2739
2740impl<T: 'static> ValueHandle<T> {
2741    fn new(tag_type_id: TypeId, id: usize, ref_counts: &Arc<Mutex<RefCounts>>) -> Self {
2742        ref_counts.lock().inc_value(tag_type_id, id);
2743        Self {
2744            value_type: PhantomData,
2745            tag_type_id,
2746            id,
2747            ref_counts: Arc::downgrade(ref_counts),
2748        }
2749    }
2750
2751    pub fn read<R>(&self, cx: &AppContext, f: impl FnOnce(&T) -> R) -> R {
2752        f(cx.values
2753            .read()
2754            .get(&(self.tag_type_id, self.id))
2755            .unwrap()
2756            .downcast_ref()
2757            .unwrap())
2758    }
2759
2760    pub fn update<R>(
2761        &self,
2762        cx: &mut EventContext,
2763        f: impl FnOnce(&mut T, &mut EventContext) -> R,
2764    ) -> R {
2765        let mut value = cx
2766            .app
2767            .cx
2768            .values
2769            .write()
2770            .remove(&(self.tag_type_id, self.id))
2771            .unwrap();
2772        let result = f(value.downcast_mut().unwrap(), cx);
2773        cx.app
2774            .cx
2775            .values
2776            .write()
2777            .insert((self.tag_type_id, self.id), value);
2778        result
2779    }
2780}
2781
2782impl<T> Drop for ValueHandle<T> {
2783    fn drop(&mut self) {
2784        if let Some(ref_counts) = self.ref_counts.upgrade() {
2785            ref_counts.lock().dec_value(self.tag_type_id, self.id);
2786        }
2787    }
2788}
2789
2790#[derive(Default)]
2791struct RefCounts {
2792    entity_counts: HashMap<usize, usize>,
2793    value_counts: HashMap<(TypeId, usize), usize>,
2794    dropped_models: HashSet<usize>,
2795    dropped_views: HashSet<(usize, usize)>,
2796    dropped_values: HashSet<(TypeId, usize)>,
2797}
2798
2799impl RefCounts {
2800    fn inc_model(&mut self, model_id: usize) {
2801        match self.entity_counts.entry(model_id) {
2802            Entry::Occupied(mut entry) => *entry.get_mut() += 1,
2803            Entry::Vacant(entry) => {
2804                entry.insert(1);
2805                self.dropped_models.remove(&model_id);
2806            }
2807        }
2808    }
2809
2810    fn inc_view(&mut self, window_id: usize, view_id: usize) {
2811        match self.entity_counts.entry(view_id) {
2812            Entry::Occupied(mut entry) => *entry.get_mut() += 1,
2813            Entry::Vacant(entry) => {
2814                entry.insert(1);
2815                self.dropped_views.remove(&(window_id, view_id));
2816            }
2817        }
2818    }
2819
2820    fn inc_value(&mut self, tag_type_id: TypeId, id: usize) {
2821        *self.value_counts.entry((tag_type_id, id)).or_insert(0) += 1;
2822    }
2823
2824    fn dec_model(&mut self, model_id: usize) {
2825        let count = self.entity_counts.get_mut(&model_id).unwrap();
2826        *count -= 1;
2827        if *count == 0 {
2828            self.entity_counts.remove(&model_id);
2829            self.dropped_models.insert(model_id);
2830        }
2831    }
2832
2833    fn dec_view(&mut self, window_id: usize, view_id: usize) {
2834        let count = self.entity_counts.get_mut(&view_id).unwrap();
2835        *count -= 1;
2836        if *count == 0 {
2837            self.entity_counts.remove(&view_id);
2838            self.dropped_views.insert((window_id, view_id));
2839        }
2840    }
2841
2842    fn dec_value(&mut self, tag_type_id: TypeId, id: usize) {
2843        let key = (tag_type_id, id);
2844        let count = self.value_counts.get_mut(&key).unwrap();
2845        *count -= 1;
2846        if *count == 0 {
2847            self.value_counts.remove(&key);
2848            self.dropped_values.insert(key);
2849        }
2850    }
2851
2852    fn is_entity_alive(&self, entity_id: usize) -> bool {
2853        self.entity_counts.contains_key(&entity_id)
2854    }
2855
2856    fn take_dropped(
2857        &mut self,
2858    ) -> (
2859        HashSet<usize>,
2860        HashSet<(usize, usize)>,
2861        HashSet<(TypeId, usize)>,
2862    ) {
2863        let mut dropped_models = HashSet::new();
2864        let mut dropped_views = HashSet::new();
2865        let mut dropped_values = HashSet::new();
2866        std::mem::swap(&mut self.dropped_models, &mut dropped_models);
2867        std::mem::swap(&mut self.dropped_views, &mut dropped_views);
2868        std::mem::swap(&mut self.dropped_values, &mut dropped_values);
2869        (dropped_models, dropped_views, dropped_values)
2870    }
2871}
2872
2873enum Subscription {
2874    FromModel {
2875        model_id: usize,
2876        callback: Box<dyn FnMut(&mut dyn Any, &dyn Any, &mut MutableAppContext, usize)>,
2877    },
2878    FromView {
2879        window_id: usize,
2880        view_id: usize,
2881        callback: Box<dyn FnMut(&mut dyn Any, &dyn Any, &mut MutableAppContext, usize, usize)>,
2882    },
2883}
2884
2885enum ModelObservation {
2886    FromModel {
2887        model_id: usize,
2888        callback: Box<dyn FnMut(&mut dyn Any, usize, &mut MutableAppContext, usize)>,
2889    },
2890    FromView {
2891        window_id: usize,
2892        view_id: usize,
2893        callback: Box<dyn FnMut(&mut dyn Any, usize, &mut MutableAppContext, usize, usize)>,
2894    },
2895}
2896
2897struct ViewObservation {
2898    window_id: usize,
2899    view_id: usize,
2900    callback: Box<dyn FnMut(&mut dyn Any, usize, usize, &mut MutableAppContext, usize, usize)>,
2901}
2902
2903#[cfg(test)]
2904mod tests {
2905    use super::*;
2906    use crate::elements::*;
2907    use smol::future::poll_once;
2908    use std::sync::atomic::{AtomicUsize, Ordering::SeqCst};
2909
2910    #[crate::test(self)]
2911    fn test_model_handles(cx: &mut MutableAppContext) {
2912        struct Model {
2913            other: Option<ModelHandle<Model>>,
2914            events: Vec<String>,
2915        }
2916
2917        impl Entity for Model {
2918            type Event = usize;
2919        }
2920
2921        impl Model {
2922            fn new(other: Option<ModelHandle<Self>>, cx: &mut ModelContext<Self>) -> Self {
2923                if let Some(other) = other.as_ref() {
2924                    cx.observe(other, |me, _, _| {
2925                        me.events.push("notified".into());
2926                    });
2927                    cx.subscribe(other, |me, event, _| {
2928                        me.events.push(format!("observed event {}", event));
2929                    });
2930                }
2931
2932                Self {
2933                    other,
2934                    events: Vec::new(),
2935                }
2936            }
2937        }
2938
2939        let handle_1 = cx.add_model(|cx| Model::new(None, cx));
2940        let handle_2 = cx.add_model(|cx| Model::new(Some(handle_1.clone()), cx));
2941        assert_eq!(cx.cx.models.len(), 2);
2942
2943        handle_1.update(cx, |model, cx| {
2944            model.events.push("updated".into());
2945            cx.emit(1);
2946            cx.notify();
2947            cx.emit(2);
2948        });
2949        assert_eq!(handle_1.read(cx).events, vec!["updated".to_string()]);
2950        assert_eq!(
2951            handle_2.read(cx).events,
2952            vec![
2953                "observed event 1".to_string(),
2954                "notified".to_string(),
2955                "observed event 2".to_string(),
2956            ]
2957        );
2958
2959        handle_2.update(cx, |model, _| {
2960            drop(handle_1);
2961            model.other.take();
2962        });
2963
2964        assert_eq!(cx.cx.models.len(), 1);
2965        assert!(cx.subscriptions.is_empty());
2966        assert!(cx.model_observations.is_empty());
2967    }
2968
2969    #[crate::test(self)]
2970    fn test_subscribe_and_emit_from_model(cx: &mut MutableAppContext) {
2971        #[derive(Default)]
2972        struct Model {
2973            events: Vec<usize>,
2974        }
2975
2976        impl Entity for Model {
2977            type Event = usize;
2978        }
2979
2980        let handle_1 = cx.add_model(|_| Model::default());
2981        let handle_2 = cx.add_model(|_| Model::default());
2982        let handle_2b = handle_2.clone();
2983
2984        handle_1.update(cx, |_, c| {
2985            c.subscribe(&handle_2, move |model: &mut Model, event, c| {
2986                model.events.push(*event);
2987
2988                c.subscribe(&handle_2b, |model, event, _| {
2989                    model.events.push(*event * 2);
2990                });
2991            });
2992        });
2993
2994        handle_2.update(cx, |_, c| c.emit(7));
2995        assert_eq!(handle_1.read(cx).events, vec![7]);
2996
2997        handle_2.update(cx, |_, c| c.emit(5));
2998        assert_eq!(handle_1.read(cx).events, vec![7, 10, 5]);
2999    }
3000
3001    #[crate::test(self)]
3002    fn test_observe_and_notify_from_model(cx: &mut MutableAppContext) {
3003        #[derive(Default)]
3004        struct Model {
3005            count: usize,
3006            events: Vec<usize>,
3007        }
3008
3009        impl Entity for Model {
3010            type Event = ();
3011        }
3012
3013        let handle_1 = cx.add_model(|_| Model::default());
3014        let handle_2 = cx.add_model(|_| Model::default());
3015        let handle_2b = handle_2.clone();
3016
3017        handle_1.update(cx, |_, c| {
3018            c.observe(&handle_2, move |model, observed, c| {
3019                model.events.push(observed.read(c).count);
3020                c.observe(&handle_2b, |model, observed, c| {
3021                    model.events.push(observed.read(c).count * 2);
3022                });
3023            });
3024        });
3025
3026        handle_2.update(cx, |model, c| {
3027            model.count = 7;
3028            c.notify()
3029        });
3030        assert_eq!(handle_1.read(cx).events, vec![7]);
3031
3032        handle_2.update(cx, |model, c| {
3033            model.count = 5;
3034            c.notify()
3035        });
3036        assert_eq!(handle_1.read(cx).events, vec![7, 10, 5])
3037    }
3038
3039    #[crate::test(self)]
3040    fn test_view_handles(cx: &mut MutableAppContext) {
3041        struct View {
3042            other: Option<ViewHandle<View>>,
3043            events: Vec<String>,
3044        }
3045
3046        impl Entity for View {
3047            type Event = usize;
3048        }
3049
3050        impl super::View for View {
3051            fn render<'a>(&self, _: &RenderContext<Self>) -> ElementBox {
3052                Empty::new().boxed()
3053            }
3054
3055            fn ui_name() -> &'static str {
3056                "View"
3057            }
3058        }
3059
3060        impl View {
3061            fn new(other: Option<ViewHandle<View>>, cx: &mut ViewContext<Self>) -> Self {
3062                if let Some(other) = other.as_ref() {
3063                    cx.subscribe_to_view(other, |me, _, event, _| {
3064                        me.events.push(format!("observed event {}", event));
3065                    });
3066                }
3067                Self {
3068                    other,
3069                    events: Vec::new(),
3070                }
3071            }
3072        }
3073
3074        let (window_id, _) = cx.add_window(Default::default(), |cx| View::new(None, cx));
3075        let handle_1 = cx.add_view(window_id, |cx| View::new(None, cx));
3076        let handle_2 = cx.add_view(window_id, |cx| View::new(Some(handle_1.clone()), cx));
3077        assert_eq!(cx.cx.views.len(), 3);
3078
3079        handle_1.update(cx, |view, cx| {
3080            view.events.push("updated".into());
3081            cx.emit(1);
3082            cx.emit(2);
3083        });
3084        assert_eq!(handle_1.read(cx).events, vec!["updated".to_string()]);
3085        assert_eq!(
3086            handle_2.read(cx).events,
3087            vec![
3088                "observed event 1".to_string(),
3089                "observed event 2".to_string(),
3090            ]
3091        );
3092
3093        handle_2.update(cx, |view, _| {
3094            drop(handle_1);
3095            view.other.take();
3096        });
3097
3098        assert_eq!(cx.cx.views.len(), 2);
3099        assert!(cx.subscriptions.is_empty());
3100        assert!(cx.model_observations.is_empty());
3101    }
3102
3103    #[crate::test(self)]
3104    fn test_add_window(cx: &mut MutableAppContext) {
3105        struct View {
3106            mouse_down_count: Arc<AtomicUsize>,
3107        }
3108
3109        impl Entity for View {
3110            type Event = ();
3111        }
3112
3113        impl super::View for View {
3114            fn render<'a>(&self, _: &RenderContext<Self>) -> ElementBox {
3115                let mouse_down_count = self.mouse_down_count.clone();
3116                EventHandler::new(Empty::new().boxed())
3117                    .on_mouse_down(move |_| {
3118                        mouse_down_count.fetch_add(1, SeqCst);
3119                        true
3120                    })
3121                    .boxed()
3122            }
3123
3124            fn ui_name() -> &'static str {
3125                "View"
3126            }
3127        }
3128
3129        let mouse_down_count = Arc::new(AtomicUsize::new(0));
3130        let (window_id, _) = cx.add_window(Default::default(), |_| View {
3131            mouse_down_count: mouse_down_count.clone(),
3132        });
3133        let presenter = cx.presenters_and_platform_windows[&window_id].0.clone();
3134        // Ensure window's root element is in a valid lifecycle state.
3135        presenter.borrow_mut().dispatch_event(
3136            Event::LeftMouseDown {
3137                position: Default::default(),
3138                cmd: false,
3139            },
3140            cx,
3141        );
3142        assert_eq!(mouse_down_count.load(SeqCst), 1);
3143    }
3144
3145    #[crate::test(self)]
3146    fn test_entity_release_hooks(cx: &mut MutableAppContext) {
3147        struct Model {
3148            released: Arc<Mutex<bool>>,
3149        }
3150
3151        struct View {
3152            released: Arc<Mutex<bool>>,
3153        }
3154
3155        impl Entity for Model {
3156            type Event = ();
3157
3158            fn release(&mut self, _: &mut MutableAppContext) {
3159                *self.released.lock() = true;
3160            }
3161        }
3162
3163        impl Entity for View {
3164            type Event = ();
3165
3166            fn release(&mut self, _: &mut MutableAppContext) {
3167                *self.released.lock() = true;
3168            }
3169        }
3170
3171        impl super::View for View {
3172            fn ui_name() -> &'static str {
3173                "View"
3174            }
3175
3176            fn render<'a>(&self, _: &RenderContext<Self>) -> ElementBox {
3177                Empty::new().boxed()
3178            }
3179        }
3180
3181        let model_released = Arc::new(Mutex::new(false));
3182        let view_released = Arc::new(Mutex::new(false));
3183
3184        let model = cx.add_model(|_| Model {
3185            released: model_released.clone(),
3186        });
3187
3188        let (window_id, _) = cx.add_window(Default::default(), |_| View {
3189            released: view_released.clone(),
3190        });
3191
3192        assert!(!*model_released.lock());
3193        assert!(!*view_released.lock());
3194
3195        cx.update(move || {
3196            drop(model);
3197        });
3198        assert!(*model_released.lock());
3199
3200        drop(cx.remove_window(window_id));
3201        assert!(*view_released.lock());
3202    }
3203
3204    #[crate::test(self)]
3205    fn test_subscribe_and_emit_from_view(cx: &mut MutableAppContext) {
3206        #[derive(Default)]
3207        struct View {
3208            events: Vec<usize>,
3209        }
3210
3211        impl Entity for View {
3212            type Event = usize;
3213        }
3214
3215        impl super::View for View {
3216            fn render<'a>(&self, _: &RenderContext<Self>) -> ElementBox {
3217                Empty::new().boxed()
3218            }
3219
3220            fn ui_name() -> &'static str {
3221                "View"
3222            }
3223        }
3224
3225        struct Model;
3226
3227        impl Entity for Model {
3228            type Event = usize;
3229        }
3230
3231        let (window_id, handle_1) = cx.add_window(Default::default(), |_| View::default());
3232        let handle_2 = cx.add_view(window_id, |_| View::default());
3233        let handle_2b = handle_2.clone();
3234        let handle_3 = cx.add_model(|_| Model);
3235
3236        handle_1.update(cx, |_, c| {
3237            c.subscribe_to_view(&handle_2, move |me, _, event, c| {
3238                me.events.push(*event);
3239
3240                c.subscribe_to_view(&handle_2b, |me, _, event, _| {
3241                    me.events.push(*event * 2);
3242                });
3243            });
3244
3245            c.subscribe_to_model(&handle_3, |me, _, event, _| {
3246                me.events.push(*event);
3247            })
3248        });
3249
3250        handle_2.update(cx, |_, c| c.emit(7));
3251        assert_eq!(handle_1.read(cx).events, vec![7]);
3252
3253        handle_2.update(cx, |_, c| c.emit(5));
3254        assert_eq!(handle_1.read(cx).events, vec![7, 10, 5]);
3255
3256        handle_3.update(cx, |_, c| c.emit(9));
3257        assert_eq!(handle_1.read(cx).events, vec![7, 10, 5, 9]);
3258    }
3259
3260    #[crate::test(self)]
3261    fn test_dropping_subscribers(cx: &mut MutableAppContext) {
3262        struct View;
3263
3264        impl Entity for View {
3265            type Event = ();
3266        }
3267
3268        impl super::View for View {
3269            fn render<'a>(&self, _: &RenderContext<Self>) -> ElementBox {
3270                Empty::new().boxed()
3271            }
3272
3273            fn ui_name() -> &'static str {
3274                "View"
3275            }
3276        }
3277
3278        struct Model;
3279
3280        impl Entity for Model {
3281            type Event = ();
3282        }
3283
3284        let (window_id, _) = cx.add_window(Default::default(), |_| View);
3285        let observing_view = cx.add_view(window_id, |_| View);
3286        let emitting_view = cx.add_view(window_id, |_| View);
3287        let observing_model = cx.add_model(|_| Model);
3288        let observed_model = cx.add_model(|_| Model);
3289
3290        observing_view.update(cx, |_, cx| {
3291            cx.subscribe_to_view(&emitting_view, |_, _, _, _| {});
3292            cx.subscribe_to_model(&observed_model, |_, _, _, _| {});
3293        });
3294        observing_model.update(cx, |_, cx| {
3295            cx.subscribe(&observed_model, |_, _, _| {});
3296        });
3297
3298        cx.update(|| {
3299            drop(observing_view);
3300            drop(observing_model);
3301        });
3302
3303        emitting_view.update(cx, |_, cx| cx.emit(()));
3304        observed_model.update(cx, |_, cx| cx.emit(()));
3305    }
3306
3307    #[crate::test(self)]
3308    fn test_observe_and_notify_from_view(cx: &mut MutableAppContext) {
3309        #[derive(Default)]
3310        struct View {
3311            events: Vec<usize>,
3312        }
3313
3314        impl Entity for View {
3315            type Event = usize;
3316        }
3317
3318        impl super::View for View {
3319            fn render<'a>(&self, _: &RenderContext<Self>) -> ElementBox {
3320                Empty::new().boxed()
3321            }
3322
3323            fn ui_name() -> &'static str {
3324                "View"
3325            }
3326        }
3327
3328        #[derive(Default)]
3329        struct Model {
3330            count: usize,
3331        }
3332
3333        impl Entity for Model {
3334            type Event = ();
3335        }
3336
3337        let (_, view) = cx.add_window(Default::default(), |_| View::default());
3338        let model = cx.add_model(|_| Model::default());
3339
3340        view.update(cx, |_, c| {
3341            c.observe_model(&model, |me, observed, c| {
3342                me.events.push(observed.read(c).count)
3343            });
3344        });
3345
3346        model.update(cx, |model, c| {
3347            model.count = 11;
3348            c.notify();
3349        });
3350        assert_eq!(view.read(cx).events, vec![11]);
3351    }
3352
3353    #[crate::test(self)]
3354    fn test_dropping_observers(cx: &mut MutableAppContext) {
3355        struct View;
3356
3357        impl Entity for View {
3358            type Event = ();
3359        }
3360
3361        impl super::View for View {
3362            fn render<'a>(&self, _: &RenderContext<Self>) -> ElementBox {
3363                Empty::new().boxed()
3364            }
3365
3366            fn ui_name() -> &'static str {
3367                "View"
3368            }
3369        }
3370
3371        struct Model;
3372
3373        impl Entity for Model {
3374            type Event = ();
3375        }
3376
3377        let (window_id, _) = cx.add_window(Default::default(), |_| View);
3378        let observing_view = cx.add_view(window_id, |_| View);
3379        let observing_model = cx.add_model(|_| Model);
3380        let observed_model = cx.add_model(|_| Model);
3381
3382        observing_view.update(cx, |_, cx| {
3383            cx.observe_model(&observed_model, |_, _, _| {});
3384        });
3385        observing_model.update(cx, |_, cx| {
3386            cx.observe(&observed_model, |_, _, _| {});
3387        });
3388
3389        cx.update(|| {
3390            drop(observing_view);
3391            drop(observing_model);
3392        });
3393
3394        observed_model.update(cx, |_, cx| cx.notify());
3395    }
3396
3397    #[crate::test(self)]
3398    fn test_focus(cx: &mut MutableAppContext) {
3399        struct View {
3400            name: String,
3401            events: Arc<Mutex<Vec<String>>>,
3402        }
3403
3404        impl Entity for View {
3405            type Event = ();
3406        }
3407
3408        impl super::View for View {
3409            fn render<'a>(&self, _: &RenderContext<Self>) -> ElementBox {
3410                Empty::new().boxed()
3411            }
3412
3413            fn ui_name() -> &'static str {
3414                "View"
3415            }
3416
3417            fn on_focus(&mut self, _: &mut ViewContext<Self>) {
3418                self.events.lock().push(format!("{} focused", &self.name));
3419            }
3420
3421            fn on_blur(&mut self, _: &mut ViewContext<Self>) {
3422                self.events.lock().push(format!("{} blurred", &self.name));
3423            }
3424        }
3425
3426        let events: Arc<Mutex<Vec<String>>> = Default::default();
3427        let (window_id, view_1) = cx.add_window(Default::default(), |_| View {
3428            events: events.clone(),
3429            name: "view 1".to_string(),
3430        });
3431        let view_2 = cx.add_view(window_id, |_| View {
3432            events: events.clone(),
3433            name: "view 2".to_string(),
3434        });
3435
3436        view_1.update(cx, |_, cx| cx.focus(&view_2));
3437        view_1.update(cx, |_, cx| cx.focus(&view_1));
3438        view_1.update(cx, |_, cx| cx.focus(&view_2));
3439        view_1.update(cx, |_, _| drop(view_2));
3440
3441        assert_eq!(
3442            *events.lock(),
3443            [
3444                "view 1 focused".to_string(),
3445                "view 1 blurred".to_string(),
3446                "view 2 focused".to_string(),
3447                "view 2 blurred".to_string(),
3448                "view 1 focused".to_string(),
3449                "view 1 blurred".to_string(),
3450                "view 2 focused".to_string(),
3451                "view 1 focused".to_string(),
3452            ],
3453        );
3454    }
3455
3456    #[crate::test(self)]
3457    fn test_dispatch_action(cx: &mut MutableAppContext) {
3458        struct ViewA {
3459            id: usize,
3460        }
3461
3462        impl Entity for ViewA {
3463            type Event = ();
3464        }
3465
3466        impl View for ViewA {
3467            fn render<'a>(&self, _: &RenderContext<Self>) -> ElementBox {
3468                Empty::new().boxed()
3469            }
3470
3471            fn ui_name() -> &'static str {
3472                "View"
3473            }
3474        }
3475
3476        struct ViewB {
3477            id: usize,
3478        }
3479
3480        impl Entity for ViewB {
3481            type Event = ();
3482        }
3483
3484        impl View for ViewB {
3485            fn render<'a>(&self, _: &RenderContext<Self>) -> ElementBox {
3486                Empty::new().boxed()
3487            }
3488
3489            fn ui_name() -> &'static str {
3490                "View"
3491            }
3492        }
3493
3494        struct ActionArg {
3495            foo: String,
3496        }
3497
3498        let actions = Rc::new(RefCell::new(Vec::new()));
3499
3500        let actions_clone = actions.clone();
3501        cx.add_global_action("action", move |_: &ActionArg, _: &mut MutableAppContext| {
3502            actions_clone.borrow_mut().push("global a".to_string());
3503        });
3504
3505        let actions_clone = actions.clone();
3506        cx.add_global_action("action", move |_: &ActionArg, _: &mut MutableAppContext| {
3507            actions_clone.borrow_mut().push("global b".to_string());
3508        });
3509
3510        let actions_clone = actions.clone();
3511        cx.add_action("action", move |view: &mut ViewA, arg: &ActionArg, cx| {
3512            assert_eq!(arg.foo, "bar");
3513            cx.propagate_action();
3514            actions_clone.borrow_mut().push(format!("{} a", view.id));
3515        });
3516
3517        let actions_clone = actions.clone();
3518        cx.add_action("action", move |view: &mut ViewA, _: &ActionArg, cx| {
3519            if view.id != 1 {
3520                cx.propagate_action();
3521            }
3522            actions_clone.borrow_mut().push(format!("{} b", view.id));
3523        });
3524
3525        let actions_clone = actions.clone();
3526        cx.add_action("action", move |view: &mut ViewB, _: &ActionArg, cx| {
3527            cx.propagate_action();
3528            actions_clone.borrow_mut().push(format!("{} c", view.id));
3529        });
3530
3531        let actions_clone = actions.clone();
3532        cx.add_action("action", move |view: &mut ViewB, _: &ActionArg, cx| {
3533            cx.propagate_action();
3534            actions_clone.borrow_mut().push(format!("{} d", view.id));
3535        });
3536
3537        let (window_id, view_1) = cx.add_window(Default::default(), |_| ViewA { id: 1 });
3538        let view_2 = cx.add_view(window_id, |_| ViewB { id: 2 });
3539        let view_3 = cx.add_view(window_id, |_| ViewA { id: 3 });
3540        let view_4 = cx.add_view(window_id, |_| ViewB { id: 4 });
3541
3542        cx.dispatch_action(
3543            window_id,
3544            vec![view_1.id(), view_2.id(), view_3.id(), view_4.id()],
3545            "action",
3546            ActionArg { foo: "bar".into() },
3547        );
3548
3549        assert_eq!(
3550            *actions.borrow(),
3551            vec!["4 d", "4 c", "3 b", "3 a", "2 d", "2 c", "1 b"]
3552        );
3553
3554        // Remove view_1, which doesn't propagate the action
3555        actions.borrow_mut().clear();
3556        cx.dispatch_action(
3557            window_id,
3558            vec![view_2.id(), view_3.id(), view_4.id()],
3559            "action",
3560            ActionArg { foo: "bar".into() },
3561        );
3562
3563        assert_eq!(
3564            *actions.borrow(),
3565            vec!["4 d", "4 c", "3 b", "3 a", "2 d", "2 c", "global b", "global a"]
3566        );
3567    }
3568
3569    #[crate::test(self)]
3570    fn test_dispatch_keystroke(cx: &mut MutableAppContext) {
3571        use std::cell::Cell;
3572
3573        #[derive(Clone)]
3574        struct ActionArg {
3575            key: String,
3576        }
3577
3578        struct View {
3579            id: usize,
3580            keymap_context: keymap::Context,
3581        }
3582
3583        impl Entity for View {
3584            type Event = ();
3585        }
3586
3587        impl super::View for View {
3588            fn render<'a>(&self, _: &RenderContext<Self>) -> ElementBox {
3589                Empty::new().boxed()
3590            }
3591
3592            fn ui_name() -> &'static str {
3593                "View"
3594            }
3595
3596            fn keymap_context(&self, _: &AppContext) -> keymap::Context {
3597                self.keymap_context.clone()
3598            }
3599        }
3600
3601        impl View {
3602            fn new(id: usize) -> Self {
3603                View {
3604                    id,
3605                    keymap_context: keymap::Context::default(),
3606                }
3607            }
3608        }
3609
3610        let mut view_1 = View::new(1);
3611        let mut view_2 = View::new(2);
3612        let mut view_3 = View::new(3);
3613        view_1.keymap_context.set.insert("a".into());
3614        view_2.keymap_context.set.insert("b".into());
3615        view_3.keymap_context.set.insert("c".into());
3616
3617        let (window_id, view_1) = cx.add_window(Default::default(), |_| view_1);
3618        let view_2 = cx.add_view(window_id, |_| view_2);
3619        let view_3 = cx.add_view(window_id, |_| view_3);
3620
3621        // This keymap's only binding dispatches an action on view 2 because that view will have
3622        // "a" and "b" in its context, but not "c".
3623        let binding = keymap::Binding::new("a", "action", Some("a && b && !c"))
3624            .with_arg(ActionArg { key: "a".into() });
3625        cx.add_bindings(vec![binding]);
3626
3627        let handled_action = Rc::new(Cell::new(false));
3628        let handled_action_clone = handled_action.clone();
3629        cx.add_action("action", move |view: &mut View, arg: &ActionArg, _| {
3630            handled_action_clone.set(true);
3631            assert_eq!(view.id, 2);
3632            assert_eq!(arg.key, "a");
3633        });
3634
3635        cx.dispatch_keystroke(
3636            window_id,
3637            vec![view_1.id(), view_2.id(), view_3.id()],
3638            &Keystroke::parse("a").unwrap(),
3639        )
3640        .unwrap();
3641
3642        assert!(handled_action.get());
3643    }
3644
3645    #[crate::test(self)]
3646    async fn test_model_condition(mut cx: TestAppContext) {
3647        struct Counter(usize);
3648
3649        impl super::Entity for Counter {
3650            type Event = ();
3651        }
3652
3653        impl Counter {
3654            fn inc(&mut self, cx: &mut ModelContext<Self>) {
3655                self.0 += 1;
3656                cx.notify();
3657            }
3658        }
3659
3660        let model = cx.add_model(|_| Counter(0));
3661
3662        let condition1 = model.condition(&cx, |model, _| model.0 == 2);
3663        let condition2 = model.condition(&cx, |model, _| model.0 == 3);
3664        smol::pin!(condition1, condition2);
3665
3666        model.update(&mut cx, |model, cx| model.inc(cx));
3667        assert_eq!(poll_once(&mut condition1).await, None);
3668        assert_eq!(poll_once(&mut condition2).await, None);
3669
3670        model.update(&mut cx, |model, cx| model.inc(cx));
3671        assert_eq!(poll_once(&mut condition1).await, Some(()));
3672        assert_eq!(poll_once(&mut condition2).await, None);
3673
3674        model.update(&mut cx, |model, cx| model.inc(cx));
3675        assert_eq!(poll_once(&mut condition2).await, Some(()));
3676
3677        model.update(&mut cx, |_, cx| cx.notify());
3678    }
3679
3680    #[crate::test(self)]
3681    #[should_panic]
3682    async fn test_model_condition_timeout(mut cx: TestAppContext) {
3683        struct Model;
3684
3685        impl super::Entity for Model {
3686            type Event = ();
3687        }
3688
3689        let model = cx.add_model(|_| Model);
3690        model.condition(&cx, |_, _| false).await;
3691    }
3692
3693    #[crate::test(self)]
3694    #[should_panic(expected = "model dropped with pending condition")]
3695    async fn test_model_condition_panic_on_drop(mut cx: TestAppContext) {
3696        struct Model;
3697
3698        impl super::Entity for Model {
3699            type Event = ();
3700        }
3701
3702        let model = cx.add_model(|_| Model);
3703        let condition = model.condition(&cx, |_, _| false);
3704        cx.update(|_| drop(model));
3705        condition.await;
3706    }
3707
3708    #[crate::test(self)]
3709    async fn test_view_condition(mut cx: TestAppContext) {
3710        struct Counter(usize);
3711
3712        impl super::Entity for Counter {
3713            type Event = ();
3714        }
3715
3716        impl super::View for Counter {
3717            fn ui_name() -> &'static str {
3718                "test view"
3719            }
3720
3721            fn render(&self, _: &RenderContext<Self>) -> ElementBox {
3722                Empty::new().boxed()
3723            }
3724        }
3725
3726        impl Counter {
3727            fn inc(&mut self, cx: &mut ViewContext<Self>) {
3728                self.0 += 1;
3729                cx.notify();
3730            }
3731        }
3732
3733        let (_, view) = cx.add_window(|_| Counter(0));
3734
3735        let condition1 = view.condition(&cx, |view, _| view.0 == 2);
3736        let condition2 = view.condition(&cx, |view, _| view.0 == 3);
3737        smol::pin!(condition1, condition2);
3738
3739        view.update(&mut cx, |view, cx| view.inc(cx));
3740        assert_eq!(poll_once(&mut condition1).await, None);
3741        assert_eq!(poll_once(&mut condition2).await, None);
3742
3743        view.update(&mut cx, |view, cx| view.inc(cx));
3744        assert_eq!(poll_once(&mut condition1).await, Some(()));
3745        assert_eq!(poll_once(&mut condition2).await, None);
3746
3747        view.update(&mut cx, |view, cx| view.inc(cx));
3748        assert_eq!(poll_once(&mut condition2).await, Some(()));
3749        view.update(&mut cx, |_, cx| cx.notify());
3750    }
3751
3752    #[crate::test(self)]
3753    #[should_panic]
3754    async fn test_view_condition_timeout(mut cx: TestAppContext) {
3755        struct View;
3756
3757        impl super::Entity for View {
3758            type Event = ();
3759        }
3760
3761        impl super::View for View {
3762            fn ui_name() -> &'static str {
3763                "test view"
3764            }
3765
3766            fn render(&self, _: &RenderContext<Self>) -> ElementBox {
3767                Empty::new().boxed()
3768            }
3769        }
3770
3771        let (_, view) = cx.add_window(|_| View);
3772        view.condition(&cx, |_, _| false).await;
3773    }
3774
3775    #[crate::test(self)]
3776    #[should_panic(expected = "view dropped with pending condition")]
3777    async fn test_view_condition_panic_on_drop(mut cx: TestAppContext) {
3778        struct View;
3779
3780        impl super::Entity for View {
3781            type Event = ();
3782        }
3783
3784        impl super::View for View {
3785            fn ui_name() -> &'static str {
3786                "test view"
3787            }
3788
3789            fn render(&self, _: &RenderContext<Self>) -> ElementBox {
3790                Empty::new().boxed()
3791            }
3792        }
3793
3794        let window_id = cx.add_window(|_| View).0;
3795        let view = cx.add_view(window_id, |_| View);
3796
3797        let condition = view.condition(&cx, |_, _| false);
3798        cx.update(|_| drop(view));
3799        condition.await;
3800    }
3801}