app.rs

   1use crate::{
   2    elements::ElementBox,
   3    executor::{self, Task},
   4    keymap::{self, Keystroke},
   5    platform::{self, CursorStyle, Platform, PromptLevel, WindowOptions},
   6    presenter::Presenter,
   7    util::{post_inc, timeout},
   8    AssetCache, AssetSource, ClipboardItem, FontCache, PathPromptOptions, TextLayoutCache,
   9};
  10use anyhow::{anyhow, Result};
  11use keymap::MatchResult;
  12use parking_lot::Mutex;
  13use platform::Event;
  14use postage::{mpsc, sink::Sink as _, stream::Stream as _};
  15use smol::prelude::*;
  16use std::{
  17    any::{type_name, Any, TypeId},
  18    cell::RefCell,
  19    collections::{hash_map::Entry, BTreeMap, HashMap, HashSet, VecDeque},
  20    fmt::{self, Debug},
  21    hash::{Hash, Hasher},
  22    marker::PhantomData,
  23    mem,
  24    ops::{Deref, DerefMut},
  25    path::{Path, PathBuf},
  26    pin::Pin,
  27    rc::{self, Rc},
  28    sync::{
  29        atomic::{AtomicUsize, Ordering::SeqCst},
  30        Arc, Weak,
  31    },
  32    time::Duration,
  33};
  34
  35pub trait Entity: 'static {
  36    type Event;
  37
  38    fn release(&mut self, _: &mut MutableAppContext) {}
  39    fn app_will_quit(
  40        &mut self,
  41        _: &mut MutableAppContext,
  42    ) -> Option<Pin<Box<dyn 'static + Future<Output = ()>>>> {
  43        None
  44    }
  45}
  46
  47pub trait View: Entity + Sized {
  48    fn ui_name() -> &'static str;
  49    fn render(&mut self, cx: &mut RenderContext<'_, Self>) -> ElementBox;
  50    fn on_focus(&mut self, _: &mut ViewContext<Self>) {}
  51    fn on_blur(&mut self, _: &mut ViewContext<Self>) {}
  52    fn keymap_context(&self, _: &AppContext) -> keymap::Context {
  53        Self::default_keymap_context()
  54    }
  55    fn default_keymap_context() -> keymap::Context {
  56        let mut cx = keymap::Context::default();
  57        cx.set.insert(Self::ui_name().into());
  58        cx
  59    }
  60}
  61
  62pub trait ReadModel {
  63    fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T;
  64}
  65
  66pub trait ReadModelWith {
  67    fn read_model_with<E: Entity, T>(
  68        &self,
  69        handle: &ModelHandle<E>,
  70        read: &mut dyn FnMut(&E, &AppContext) -> T,
  71    ) -> T;
  72}
  73
  74pub trait UpdateModel {
  75    fn update_model<T: Entity, O>(
  76        &mut self,
  77        handle: &ModelHandle<T>,
  78        update: &mut dyn FnMut(&mut T, &mut ModelContext<T>) -> O,
  79    ) -> O;
  80}
  81
  82pub trait UpgradeModelHandle {
  83    fn upgrade_model_handle<T: Entity>(&self, handle: WeakModelHandle<T>)
  84        -> Option<ModelHandle<T>>;
  85}
  86
  87pub trait ReadView {
  88    fn read_view<T: View>(&self, handle: &ViewHandle<T>) -> &T;
  89}
  90
  91pub trait ReadViewWith {
  92    fn read_view_with<V, T>(
  93        &self,
  94        handle: &ViewHandle<V>,
  95        read: &mut dyn FnMut(&V, &AppContext) -> T,
  96    ) -> T
  97    where
  98        V: View;
  99}
 100
 101pub trait UpdateView {
 102    fn update_view<T, S>(
 103        &mut self,
 104        handle: &ViewHandle<T>,
 105        update: &mut dyn FnMut(&mut T, &mut ViewContext<T>) -> S,
 106    ) -> S
 107    where
 108        T: View;
 109}
 110
 111pub trait Action: 'static + AnyAction {
 112    type Argument: 'static + Clone;
 113}
 114
 115pub trait AnyAction {
 116    fn id(&self) -> TypeId;
 117    fn name(&self) -> &'static str;
 118    fn as_any(&self) -> &dyn Any;
 119    fn boxed_clone(&self) -> Box<dyn AnyAction>;
 120    fn boxed_clone_as_any(&self) -> Box<dyn Any>;
 121}
 122
 123#[macro_export]
 124macro_rules! action {
 125    ($name:ident, $arg:ty) => {
 126        #[derive(Clone)]
 127        pub struct $name(pub $arg);
 128
 129        impl $crate::Action for $name {
 130            type Argument = $arg;
 131        }
 132
 133        impl $crate::AnyAction for $name {
 134            fn id(&self) -> std::any::TypeId {
 135                std::any::TypeId::of::<$name>()
 136            }
 137
 138            fn name(&self) -> &'static str {
 139                stringify!($name)
 140            }
 141
 142            fn as_any(&self) -> &dyn std::any::Any {
 143                self
 144            }
 145
 146            fn boxed_clone(&self) -> Box<dyn $crate::AnyAction> {
 147                Box::new(self.clone())
 148            }
 149
 150            fn boxed_clone_as_any(&self) -> Box<dyn std::any::Any> {
 151                Box::new(self.clone())
 152            }
 153        }
 154    };
 155
 156    ($name:ident) => {
 157        #[derive(Clone, Debug, Eq, PartialEq)]
 158        pub struct $name;
 159
 160        impl $crate::Action for $name {
 161            type Argument = ();
 162        }
 163
 164        impl $crate::AnyAction for $name {
 165            fn id(&self) -> std::any::TypeId {
 166                std::any::TypeId::of::<$name>()
 167            }
 168
 169            fn name(&self) -> &'static str {
 170                stringify!($name)
 171            }
 172
 173            fn as_any(&self) -> &dyn std::any::Any {
 174                self
 175            }
 176
 177            fn boxed_clone(&self) -> Box<dyn $crate::AnyAction> {
 178                Box::new(self.clone())
 179            }
 180
 181            fn boxed_clone_as_any(&self) -> Box<dyn std::any::Any> {
 182                Box::new(self.clone())
 183            }
 184        }
 185    };
 186}
 187
 188pub struct Menu<'a> {
 189    pub name: &'a str,
 190    pub items: Vec<MenuItem<'a>>,
 191}
 192
 193pub enum MenuItem<'a> {
 194    Action {
 195        name: &'a str,
 196        keystroke: Option<&'a str>,
 197        action: Box<dyn AnyAction>,
 198    },
 199    Separator,
 200}
 201
 202#[derive(Clone)]
 203pub struct App(Rc<RefCell<MutableAppContext>>);
 204
 205#[derive(Clone)]
 206pub struct AsyncAppContext(Rc<RefCell<MutableAppContext>>);
 207
 208#[derive(Clone)]
 209pub struct TestAppContext {
 210    cx: Rc<RefCell<MutableAppContext>>,
 211    foreground_platform: Rc<platform::test::ForegroundPlatform>,
 212}
 213
 214impl App {
 215    pub fn new(asset_source: impl AssetSource) -> Result<Self> {
 216        let platform = platform::current::platform();
 217        let foreground_platform = platform::current::foreground_platform();
 218        let foreground = Rc::new(executor::Foreground::platform(platform.dispatcher())?);
 219        let app = Self(Rc::new(RefCell::new(MutableAppContext::new(
 220            foreground,
 221            Arc::new(executor::Background::new()),
 222            platform.clone(),
 223            foreground_platform.clone(),
 224            Arc::new(FontCache::new(platform.fonts())),
 225            asset_source,
 226        ))));
 227
 228        foreground_platform.on_quit(Box::new({
 229            let cx = app.0.clone();
 230            move || {
 231                cx.borrow_mut().quit();
 232            }
 233        }));
 234        foreground_platform.on_menu_command(Box::new({
 235            let cx = app.0.clone();
 236            move |action| {
 237                let mut cx = cx.borrow_mut();
 238                if let Some(key_window_id) = cx.cx.platform.key_window_id() {
 239                    if let Some((presenter, _)) =
 240                        cx.presenters_and_platform_windows.get(&key_window_id)
 241                    {
 242                        let presenter = presenter.clone();
 243                        let path = presenter.borrow().dispatch_path(cx.as_ref());
 244                        cx.dispatch_action_any(key_window_id, &path, action);
 245                    } else {
 246                        cx.dispatch_global_action_any(action);
 247                    }
 248                } else {
 249                    cx.dispatch_global_action_any(action);
 250                }
 251            }
 252        }));
 253
 254        app.0.borrow_mut().weak_self = Some(Rc::downgrade(&app.0));
 255        Ok(app)
 256    }
 257
 258    pub fn on_become_active<F>(self, mut callback: F) -> Self
 259    where
 260        F: 'static + FnMut(&mut MutableAppContext),
 261    {
 262        let cx = self.0.clone();
 263        self.0
 264            .borrow_mut()
 265            .foreground_platform
 266            .on_become_active(Box::new(move || callback(&mut *cx.borrow_mut())));
 267        self
 268    }
 269
 270    pub fn on_resign_active<F>(self, mut callback: F) -> Self
 271    where
 272        F: 'static + FnMut(&mut MutableAppContext),
 273    {
 274        let cx = self.0.clone();
 275        self.0
 276            .borrow_mut()
 277            .foreground_platform
 278            .on_resign_active(Box::new(move || callback(&mut *cx.borrow_mut())));
 279        self
 280    }
 281
 282    pub fn on_quit<F>(self, mut callback: F) -> Self
 283    where
 284        F: 'static + FnMut(&mut MutableAppContext),
 285    {
 286        let cx = self.0.clone();
 287        self.0
 288            .borrow_mut()
 289            .foreground_platform
 290            .on_quit(Box::new(move || callback(&mut *cx.borrow_mut())));
 291        self
 292    }
 293
 294    pub fn on_event<F>(self, mut callback: F) -> Self
 295    where
 296        F: 'static + FnMut(Event, &mut MutableAppContext) -> bool,
 297    {
 298        let cx = self.0.clone();
 299        self.0
 300            .borrow_mut()
 301            .foreground_platform
 302            .on_event(Box::new(move |event| {
 303                callback(event, &mut *cx.borrow_mut())
 304            }));
 305        self
 306    }
 307
 308    pub fn on_open_files<F>(self, mut callback: F) -> Self
 309    where
 310        F: 'static + FnMut(Vec<PathBuf>, &mut MutableAppContext),
 311    {
 312        let cx = self.0.clone();
 313        self.0
 314            .borrow_mut()
 315            .foreground_platform
 316            .on_open_files(Box::new(move |paths| {
 317                callback(paths, &mut *cx.borrow_mut())
 318            }));
 319        self
 320    }
 321
 322    pub fn run<F>(self, on_finish_launching: F)
 323    where
 324        F: 'static + FnOnce(&mut MutableAppContext),
 325    {
 326        let platform = self.0.borrow().foreground_platform.clone();
 327        platform.run(Box::new(move || {
 328            let mut cx = self.0.borrow_mut();
 329            let cx = &mut *cx;
 330            crate::views::init(cx);
 331            on_finish_launching(cx);
 332        }))
 333    }
 334
 335    pub fn platform(&self) -> Arc<dyn Platform> {
 336        self.0.borrow().platform()
 337    }
 338
 339    pub fn font_cache(&self) -> Arc<FontCache> {
 340        self.0.borrow().cx.font_cache.clone()
 341    }
 342
 343    fn update<T, F: FnOnce(&mut MutableAppContext) -> T>(&mut self, callback: F) -> T {
 344        let mut state = self.0.borrow_mut();
 345        let result = state.update(callback);
 346        state.pending_notifications.clear();
 347        result
 348    }
 349}
 350
 351impl TestAppContext {
 352    pub fn new(
 353        foreground_platform: Rc<platform::test::ForegroundPlatform>,
 354        platform: Arc<dyn Platform>,
 355        foreground: Rc<executor::Foreground>,
 356        background: Arc<executor::Background>,
 357        font_cache: Arc<FontCache>,
 358        first_entity_id: usize,
 359    ) -> Self {
 360        let mut cx = MutableAppContext::new(
 361            foreground.clone(),
 362            background,
 363            platform,
 364            foreground_platform.clone(),
 365            font_cache,
 366            (),
 367        );
 368        cx.next_entity_id = first_entity_id;
 369        let cx = TestAppContext {
 370            cx: Rc::new(RefCell::new(cx)),
 371            foreground_platform,
 372        };
 373        cx.cx.borrow_mut().weak_self = Some(Rc::downgrade(&cx.cx));
 374        cx
 375    }
 376
 377    pub fn dispatch_action<A: Action>(
 378        &self,
 379        window_id: usize,
 380        responder_chain: Vec<usize>,
 381        action: A,
 382    ) {
 383        self.cx
 384            .borrow_mut()
 385            .dispatch_action_any(window_id, &responder_chain, &action);
 386    }
 387
 388    pub fn dispatch_global_action<A: Action>(&self, action: A) {
 389        self.cx.borrow_mut().dispatch_global_action(action);
 390    }
 391
 392    pub fn dispatch_keystroke(
 393        &self,
 394        window_id: usize,
 395        responder_chain: Vec<usize>,
 396        keystroke: &Keystroke,
 397    ) -> Result<bool> {
 398        let mut state = self.cx.borrow_mut();
 399        state.dispatch_keystroke(window_id, responder_chain, keystroke)
 400    }
 401
 402    pub fn add_model<T, F>(&mut self, build_model: F) -> ModelHandle<T>
 403    where
 404        T: Entity,
 405        F: FnOnce(&mut ModelContext<T>) -> T,
 406    {
 407        self.cx.borrow_mut().add_model(build_model)
 408    }
 409
 410    pub fn add_window<T, F>(&mut self, build_root_view: F) -> (usize, ViewHandle<T>)
 411    where
 412        T: View,
 413        F: FnOnce(&mut ViewContext<T>) -> T,
 414    {
 415        self.cx
 416            .borrow_mut()
 417            .add_window(Default::default(), build_root_view)
 418    }
 419
 420    pub fn window_ids(&self) -> Vec<usize> {
 421        self.cx.borrow().window_ids().collect()
 422    }
 423
 424    pub fn root_view<T: View>(&self, window_id: usize) -> Option<ViewHandle<T>> {
 425        self.cx.borrow().root_view(window_id)
 426    }
 427
 428    pub fn add_view<T, F>(&mut self, window_id: usize, build_view: F) -> ViewHandle<T>
 429    where
 430        T: View,
 431        F: FnOnce(&mut ViewContext<T>) -> T,
 432    {
 433        self.cx.borrow_mut().add_view(window_id, build_view)
 434    }
 435
 436    pub fn add_option_view<T, F>(
 437        &mut self,
 438        window_id: usize,
 439        build_view: F,
 440    ) -> Option<ViewHandle<T>>
 441    where
 442        T: View,
 443        F: FnOnce(&mut ViewContext<T>) -> Option<T>,
 444    {
 445        self.cx.borrow_mut().add_option_view(window_id, build_view)
 446    }
 447
 448    pub fn read<T, F: FnOnce(&AppContext) -> T>(&self, callback: F) -> T {
 449        callback(self.cx.borrow().as_ref())
 450    }
 451
 452    pub fn update<T, F: FnOnce(&mut MutableAppContext) -> T>(&mut self, callback: F) -> T {
 453        let mut state = self.cx.borrow_mut();
 454        // Don't increment pending flushes in order to effects to be flushed before the callback
 455        // completes, which is helpful in tests.
 456        let result = callback(&mut *state);
 457        // Flush effects after the callback just in case there are any. This can happen in edge
 458        // cases such as the closure dropping handles.
 459        state.flush_effects();
 460        result
 461    }
 462
 463    pub fn to_async(&self) -> AsyncAppContext {
 464        AsyncAppContext(self.cx.clone())
 465    }
 466
 467    pub fn font_cache(&self) -> Arc<FontCache> {
 468        self.cx.borrow().cx.font_cache.clone()
 469    }
 470
 471    pub fn platform(&self) -> Arc<dyn platform::Platform> {
 472        self.cx.borrow().cx.platform.clone()
 473    }
 474
 475    pub fn foreground(&self) -> Rc<executor::Foreground> {
 476        self.cx.borrow().foreground().clone()
 477    }
 478
 479    pub fn background(&self) -> Arc<executor::Background> {
 480        self.cx.borrow().background().clone()
 481    }
 482
 483    pub fn simulate_new_path_selection(&self, result: impl FnOnce(PathBuf) -> Option<PathBuf>) {
 484        self.foreground_platform.simulate_new_path_selection(result);
 485    }
 486
 487    pub fn did_prompt_for_new_path(&self) -> bool {
 488        self.foreground_platform.as_ref().did_prompt_for_new_path()
 489    }
 490
 491    pub fn simulate_prompt_answer(&self, window_id: usize, answer: usize) {
 492        let mut state = self.cx.borrow_mut();
 493        let (_, window) = state
 494            .presenters_and_platform_windows
 495            .get_mut(&window_id)
 496            .unwrap();
 497        let test_window = window
 498            .as_any_mut()
 499            .downcast_mut::<platform::test::Window>()
 500            .unwrap();
 501        let callback = test_window
 502            .last_prompt
 503            .take()
 504            .expect("prompt was not called");
 505        (callback)(answer);
 506    }
 507}
 508
 509impl AsyncAppContext {
 510    pub fn spawn<F, Fut, T>(&self, f: F) -> Task<T>
 511    where
 512        F: FnOnce(AsyncAppContext) -> Fut,
 513        Fut: 'static + Future<Output = T>,
 514        T: 'static,
 515    {
 516        self.0.borrow().foreground.spawn(f(self.clone()))
 517    }
 518
 519    pub fn read<T, F: FnOnce(&AppContext) -> T>(&mut self, callback: F) -> T {
 520        callback(self.0.borrow().as_ref())
 521    }
 522
 523    pub fn update<T, F: FnOnce(&mut MutableAppContext) -> T>(&mut self, callback: F) -> T {
 524        self.0.borrow_mut().update(callback)
 525    }
 526
 527    pub fn add_model<T, F>(&mut self, build_model: F) -> ModelHandle<T>
 528    where
 529        T: Entity,
 530        F: FnOnce(&mut ModelContext<T>) -> T,
 531    {
 532        self.update(|cx| cx.add_model(build_model))
 533    }
 534
 535    pub fn platform(&self) -> Arc<dyn Platform> {
 536        self.0.borrow().platform()
 537    }
 538
 539    pub fn foreground(&self) -> Rc<executor::Foreground> {
 540        self.0.borrow().foreground.clone()
 541    }
 542
 543    pub fn background(&self) -> Arc<executor::Background> {
 544        self.0.borrow().cx.background.clone()
 545    }
 546}
 547
 548impl UpdateModel for AsyncAppContext {
 549    fn update_model<E: Entity, O>(
 550        &mut self,
 551        handle: &ModelHandle<E>,
 552        update: &mut dyn FnMut(&mut E, &mut ModelContext<E>) -> O,
 553    ) -> O {
 554        self.0.borrow_mut().update_model(handle, update)
 555    }
 556}
 557
 558impl UpgradeModelHandle for AsyncAppContext {
 559    fn upgrade_model_handle<T: Entity>(
 560        &self,
 561        handle: WeakModelHandle<T>,
 562    ) -> Option<ModelHandle<T>> {
 563        self.0.borrow_mut().upgrade_model_handle(handle)
 564    }
 565}
 566
 567impl ReadModelWith for AsyncAppContext {
 568    fn read_model_with<E: Entity, T>(
 569        &self,
 570        handle: &ModelHandle<E>,
 571        read: &mut dyn FnMut(&E, &AppContext) -> T,
 572    ) -> T {
 573        let cx = self.0.borrow();
 574        let cx = cx.as_ref();
 575        read(handle.read(cx), cx)
 576    }
 577}
 578
 579impl UpdateView for AsyncAppContext {
 580    fn update_view<T, S>(
 581        &mut self,
 582        handle: &ViewHandle<T>,
 583        update: &mut dyn FnMut(&mut T, &mut ViewContext<T>) -> S,
 584    ) -> S
 585    where
 586        T: View,
 587    {
 588        self.0.borrow_mut().update_view(handle, update)
 589    }
 590}
 591
 592impl ReadViewWith for AsyncAppContext {
 593    fn read_view_with<V, T>(
 594        &self,
 595        handle: &ViewHandle<V>,
 596        read: &mut dyn FnMut(&V, &AppContext) -> T,
 597    ) -> T
 598    where
 599        V: View,
 600    {
 601        let cx = self.0.borrow();
 602        let cx = cx.as_ref();
 603        read(handle.read(cx), cx)
 604    }
 605}
 606
 607impl UpdateModel for TestAppContext {
 608    fn update_model<T: Entity, O>(
 609        &mut self,
 610        handle: &ModelHandle<T>,
 611        update: &mut dyn FnMut(&mut T, &mut ModelContext<T>) -> O,
 612    ) -> O {
 613        self.cx.borrow_mut().update_model(handle, update)
 614    }
 615}
 616
 617impl ReadModelWith for TestAppContext {
 618    fn read_model_with<E: Entity, T>(
 619        &self,
 620        handle: &ModelHandle<E>,
 621        read: &mut dyn FnMut(&E, &AppContext) -> T,
 622    ) -> T {
 623        let cx = self.cx.borrow();
 624        let cx = cx.as_ref();
 625        read(handle.read(cx), cx)
 626    }
 627}
 628
 629impl UpdateView for TestAppContext {
 630    fn update_view<T, S>(
 631        &mut self,
 632        handle: &ViewHandle<T>,
 633        update: &mut dyn FnMut(&mut T, &mut ViewContext<T>) -> S,
 634    ) -> S
 635    where
 636        T: View,
 637    {
 638        self.cx.borrow_mut().update_view(handle, update)
 639    }
 640}
 641
 642impl ReadViewWith for TestAppContext {
 643    fn read_view_with<V, T>(
 644        &self,
 645        handle: &ViewHandle<V>,
 646        read: &mut dyn FnMut(&V, &AppContext) -> T,
 647    ) -> T
 648    where
 649        V: View,
 650    {
 651        let cx = self.cx.borrow();
 652        let cx = cx.as_ref();
 653        read(handle.read(cx), cx)
 654    }
 655}
 656
 657type ActionCallback =
 658    dyn FnMut(&mut dyn AnyView, &dyn AnyAction, &mut MutableAppContext, usize, usize) -> bool;
 659type GlobalActionCallback = dyn FnMut(&dyn AnyAction, &mut MutableAppContext);
 660
 661type SubscriptionCallback = Box<dyn FnMut(&dyn Any, &mut MutableAppContext) -> bool>;
 662type ObservationCallback = Box<dyn FnMut(&mut MutableAppContext) -> bool>;
 663
 664pub struct MutableAppContext {
 665    weak_self: Option<rc::Weak<RefCell<Self>>>,
 666    foreground_platform: Rc<dyn platform::ForegroundPlatform>,
 667    assets: Arc<AssetCache>,
 668    cx: AppContext,
 669    actions: HashMap<TypeId, HashMap<TypeId, Vec<Box<ActionCallback>>>>,
 670    global_actions: HashMap<TypeId, Box<GlobalActionCallback>>,
 671    keystroke_matcher: keymap::Matcher,
 672    next_entity_id: usize,
 673    next_window_id: usize,
 674    next_subscription_id: usize,
 675    subscriptions: Arc<Mutex<HashMap<usize, BTreeMap<usize, SubscriptionCallback>>>>,
 676    observations: Arc<Mutex<HashMap<usize, BTreeMap<usize, ObservationCallback>>>>,
 677    presenters_and_platform_windows:
 678        HashMap<usize, (Rc<RefCell<Presenter>>, Box<dyn platform::Window>)>,
 679    debug_elements_callbacks: HashMap<usize, Box<dyn Fn(&AppContext) -> crate::json::Value>>,
 680    foreground: Rc<executor::Foreground>,
 681    pending_effects: VecDeque<Effect>,
 682    pending_notifications: HashSet<usize>,
 683    pending_flushes: usize,
 684    flushing_effects: bool,
 685    next_cursor_style_handle_id: Arc<AtomicUsize>,
 686}
 687
 688impl MutableAppContext {
 689    fn new(
 690        foreground: Rc<executor::Foreground>,
 691        background: Arc<executor::Background>,
 692        platform: Arc<dyn platform::Platform>,
 693        foreground_platform: Rc<dyn platform::ForegroundPlatform>,
 694        font_cache: Arc<FontCache>,
 695        asset_source: impl AssetSource,
 696        // entity_drop_tx:
 697    ) -> Self {
 698        Self {
 699            weak_self: None,
 700            foreground_platform,
 701            assets: Arc::new(AssetCache::new(asset_source)),
 702            cx: AppContext {
 703                models: Default::default(),
 704                views: Default::default(),
 705                windows: Default::default(),
 706                element_states: Default::default(),
 707                ref_counts: Arc::new(Mutex::new(RefCounts::default())),
 708                background,
 709                font_cache,
 710                platform,
 711            },
 712            actions: HashMap::new(),
 713            global_actions: HashMap::new(),
 714            keystroke_matcher: keymap::Matcher::default(),
 715            next_entity_id: 0,
 716            next_window_id: 0,
 717            next_subscription_id: 0,
 718            subscriptions: Default::default(),
 719            observations: Default::default(),
 720            presenters_and_platform_windows: HashMap::new(),
 721            debug_elements_callbacks: HashMap::new(),
 722            foreground,
 723            pending_effects: VecDeque::new(),
 724            pending_notifications: HashSet::new(),
 725            pending_flushes: 0,
 726            flushing_effects: false,
 727            next_cursor_style_handle_id: Default::default(),
 728        }
 729    }
 730
 731    pub fn upgrade(&self) -> App {
 732        App(self.weak_self.as_ref().unwrap().upgrade().unwrap())
 733    }
 734
 735    pub fn quit(&mut self) {
 736        let mut futures = Vec::new();
 737        for model_id in self.cx.models.keys().copied().collect::<Vec<_>>() {
 738            let mut model = self.cx.models.remove(&model_id).unwrap();
 739            futures.extend(model.app_will_quit(self));
 740            self.cx.models.insert(model_id, model);
 741        }
 742
 743        for view_id in self.cx.views.keys().copied().collect::<Vec<_>>() {
 744            let mut view = self.cx.views.remove(&view_id).unwrap();
 745            futures.extend(view.app_will_quit(self));
 746            self.cx.views.insert(view_id, view);
 747        }
 748
 749        self.remove_all_windows();
 750
 751        let futures = futures::future::join_all(futures);
 752        if self
 753            .background
 754            .block_with_timeout(Duration::from_millis(100), futures)
 755            .is_err()
 756        {
 757            log::error!("timed out waiting on app_will_quit");
 758        }
 759    }
 760
 761    fn remove_all_windows(&mut self) {
 762        for (window_id, _) in self.cx.windows.drain() {
 763            self.presenters_and_platform_windows.remove(&window_id);
 764        }
 765        self.remove_dropped_entities();
 766    }
 767
 768    pub fn platform(&self) -> Arc<dyn platform::Platform> {
 769        self.cx.platform.clone()
 770    }
 771
 772    pub fn font_cache(&self) -> &Arc<FontCache> {
 773        &self.cx.font_cache
 774    }
 775
 776    pub fn foreground(&self) -> &Rc<executor::Foreground> {
 777        &self.foreground
 778    }
 779
 780    pub fn background(&self) -> &Arc<executor::Background> {
 781        &self.cx.background
 782    }
 783
 784    pub fn on_debug_elements<F>(&mut self, window_id: usize, callback: F)
 785    where
 786        F: 'static + Fn(&AppContext) -> crate::json::Value,
 787    {
 788        self.debug_elements_callbacks
 789            .insert(window_id, Box::new(callback));
 790    }
 791
 792    pub fn debug_elements(&self, window_id: usize) -> Option<crate::json::Value> {
 793        self.debug_elements_callbacks
 794            .get(&window_id)
 795            .map(|debug_elements| debug_elements(&self.cx))
 796    }
 797
 798    pub fn add_action<A, V, F>(&mut self, mut handler: F)
 799    where
 800        A: Action,
 801        V: View,
 802        F: 'static + FnMut(&mut V, &A, &mut ViewContext<V>),
 803    {
 804        let handler = Box::new(
 805            move |view: &mut dyn AnyView,
 806                  action: &dyn AnyAction,
 807                  cx: &mut MutableAppContext,
 808                  window_id: usize,
 809                  view_id: usize| {
 810                let action = action.as_any().downcast_ref().unwrap();
 811                let mut cx = ViewContext::new(cx, window_id, view_id);
 812                handler(
 813                    view.as_any_mut()
 814                        .downcast_mut()
 815                        .expect("downcast is type safe"),
 816                    action,
 817                    &mut cx,
 818                );
 819                cx.halt_action_dispatch
 820            },
 821        );
 822
 823        self.actions
 824            .entry(TypeId::of::<V>())
 825            .or_default()
 826            .entry(TypeId::of::<A>())
 827            .or_default()
 828            .push(handler);
 829    }
 830
 831    pub fn add_global_action<A, F>(&mut self, mut handler: F)
 832    where
 833        A: Action,
 834        F: 'static + FnMut(&A, &mut MutableAppContext),
 835    {
 836        let handler = Box::new(move |action: &dyn AnyAction, cx: &mut MutableAppContext| {
 837            let action = action.as_any().downcast_ref().unwrap();
 838            handler(action, cx);
 839        });
 840
 841        if self
 842            .global_actions
 843            .insert(TypeId::of::<A>(), handler)
 844            .is_some()
 845        {
 846            panic!("registered multiple global handlers for the same action type");
 847        }
 848    }
 849
 850    pub fn window_ids(&self) -> impl Iterator<Item = usize> + '_ {
 851        self.cx.windows.keys().cloned()
 852    }
 853
 854    pub fn root_view<T: View>(&self, window_id: usize) -> Option<ViewHandle<T>> {
 855        self.cx
 856            .windows
 857            .get(&window_id)
 858            .and_then(|window| window.root_view.clone().downcast::<T>())
 859    }
 860
 861    pub fn root_view_id(&self, window_id: usize) -> Option<usize> {
 862        self.cx.root_view_id(window_id)
 863    }
 864
 865    pub fn focused_view_id(&self, window_id: usize) -> Option<usize> {
 866        self.cx.focused_view_id(window_id)
 867    }
 868
 869    pub fn render_view(
 870        &mut self,
 871        window_id: usize,
 872        view_id: usize,
 873        titlebar_height: f32,
 874        refreshing: bool,
 875    ) -> Result<ElementBox> {
 876        let mut view = self
 877            .cx
 878            .views
 879            .remove(&(window_id, view_id))
 880            .ok_or(anyhow!("view not found"))?;
 881        let element = view.render(window_id, view_id, titlebar_height, refreshing, self);
 882        self.cx.views.insert((window_id, view_id), view);
 883        Ok(element)
 884    }
 885
 886    pub fn render_views(
 887        &mut self,
 888        window_id: usize,
 889        titlebar_height: f32,
 890    ) -> HashMap<usize, ElementBox> {
 891        let view_ids = self
 892            .views
 893            .keys()
 894            .filter_map(|(win_id, view_id)| {
 895                if *win_id == window_id {
 896                    Some(*view_id)
 897                } else {
 898                    None
 899                }
 900            })
 901            .collect::<Vec<_>>();
 902        view_ids
 903            .into_iter()
 904            .map(|view_id| {
 905                (
 906                    view_id,
 907                    self.render_view(window_id, view_id, titlebar_height, false)
 908                        .unwrap(),
 909                )
 910            })
 911            .collect()
 912    }
 913
 914    pub fn update<T, F: FnOnce(&mut Self) -> T>(&mut self, callback: F) -> T {
 915        self.pending_flushes += 1;
 916        let result = callback(self);
 917        self.flush_effects();
 918        result
 919    }
 920
 921    pub fn set_menus(&mut self, menus: Vec<Menu>) {
 922        self.foreground_platform.set_menus(menus);
 923    }
 924
 925    fn prompt<F>(
 926        &self,
 927        window_id: usize,
 928        level: PromptLevel,
 929        msg: &str,
 930        answers: &[&str],
 931        done_fn: F,
 932    ) where
 933        F: 'static + FnOnce(usize, &mut MutableAppContext),
 934    {
 935        let app = self.weak_self.as_ref().unwrap().upgrade().unwrap();
 936        let foreground = self.foreground.clone();
 937        let (_, window) = &self.presenters_and_platform_windows[&window_id];
 938        window.prompt(
 939            level,
 940            msg,
 941            answers,
 942            Box::new(move |answer| {
 943                foreground
 944                    .spawn(async move { (done_fn)(answer, &mut *app.borrow_mut()) })
 945                    .detach();
 946            }),
 947        );
 948    }
 949
 950    pub fn prompt_for_paths<F>(&self, options: PathPromptOptions, done_fn: F)
 951    where
 952        F: 'static + FnOnce(Option<Vec<PathBuf>>, &mut MutableAppContext),
 953    {
 954        let app = self.weak_self.as_ref().unwrap().upgrade().unwrap();
 955        let foreground = self.foreground.clone();
 956        self.foreground_platform.prompt_for_paths(
 957            options,
 958            Box::new(move |paths| {
 959                foreground
 960                    .spawn(async move { (done_fn)(paths, &mut *app.borrow_mut()) })
 961                    .detach();
 962            }),
 963        );
 964    }
 965
 966    pub fn prompt_for_new_path<F>(&self, directory: &Path, done_fn: F)
 967    where
 968        F: 'static + FnOnce(Option<PathBuf>, &mut MutableAppContext),
 969    {
 970        let app = self.weak_self.as_ref().unwrap().upgrade().unwrap();
 971        let foreground = self.foreground.clone();
 972        self.foreground_platform.prompt_for_new_path(
 973            directory,
 974            Box::new(move |path| {
 975                foreground
 976                    .spawn(async move { (done_fn)(path, &mut *app.borrow_mut()) })
 977                    .detach();
 978            }),
 979        );
 980    }
 981
 982    pub fn subscribe<E, H, F>(&mut self, handle: &H, mut callback: F) -> Subscription
 983    where
 984        E: Entity,
 985        E::Event: 'static,
 986        H: Handle<E>,
 987        F: 'static + FnMut(H, &E::Event, &mut Self),
 988    {
 989        self.subscribe_internal(handle, move |handle, event, cx| {
 990            callback(handle, event, cx);
 991            true
 992        })
 993    }
 994
 995    fn observe<E, H, F>(&mut self, handle: &H, mut callback: F) -> Subscription
 996    where
 997        E: Entity,
 998        E::Event: 'static,
 999        H: Handle<E>,
1000        F: 'static + FnMut(H, &mut Self),
1001    {
1002        self.observe_internal(handle, move |handle, cx| {
1003            callback(handle, cx);
1004            true
1005        })
1006    }
1007
1008    pub fn subscribe_internal<E, H, F>(&mut self, handle: &H, mut callback: F) -> Subscription
1009    where
1010        E: Entity,
1011        E::Event: 'static,
1012        H: Handle<E>,
1013        F: 'static + FnMut(H, &E::Event, &mut Self) -> bool,
1014    {
1015        let id = post_inc(&mut self.next_subscription_id);
1016        let emitter = handle.downgrade();
1017        self.subscriptions
1018            .lock()
1019            .entry(handle.id())
1020            .or_default()
1021            .insert(
1022                id,
1023                Box::new(move |payload, cx| {
1024                    if let Some(emitter) = H::upgrade_from(&emitter, cx.as_ref()) {
1025                        let payload = payload.downcast_ref().expect("downcast is type safe");
1026                        callback(emitter, payload, cx)
1027                    } else {
1028                        false
1029                    }
1030                }),
1031            );
1032        Subscription::Subscription {
1033            id,
1034            entity_id: handle.id(),
1035            subscriptions: Some(Arc::downgrade(&self.subscriptions)),
1036        }
1037    }
1038
1039    fn observe_internal<E, H, F>(&mut self, handle: &H, mut callback: F) -> Subscription
1040    where
1041        E: Entity,
1042        E::Event: 'static,
1043        H: Handle<E>,
1044        F: 'static + FnMut(H, &mut Self) -> bool,
1045    {
1046        let id = post_inc(&mut self.next_subscription_id);
1047        let observed = handle.downgrade();
1048        self.observations
1049            .lock()
1050            .entry(handle.id())
1051            .or_default()
1052            .insert(
1053                id,
1054                Box::new(move |cx| {
1055                    if let Some(observed) = H::upgrade_from(&observed, cx) {
1056                        callback(observed, cx)
1057                    } else {
1058                        false
1059                    }
1060                }),
1061            );
1062        Subscription::Observation {
1063            id,
1064            entity_id: handle.id(),
1065            observations: Some(Arc::downgrade(&self.observations)),
1066        }
1067    }
1068    pub(crate) fn notify_model(&mut self, model_id: usize) {
1069        if self.pending_notifications.insert(model_id) {
1070            self.pending_effects
1071                .push_back(Effect::ModelNotification { model_id });
1072        }
1073    }
1074
1075    pub(crate) fn notify_view(&mut self, window_id: usize, view_id: usize) {
1076        if self.pending_notifications.insert(view_id) {
1077            self.pending_effects
1078                .push_back(Effect::ViewNotification { window_id, view_id });
1079        }
1080    }
1081
1082    pub fn dispatch_action<A: Action>(
1083        &mut self,
1084        window_id: usize,
1085        responder_chain: Vec<usize>,
1086        action: &A,
1087    ) {
1088        self.dispatch_action_any(window_id, &responder_chain, action);
1089    }
1090
1091    pub(crate) fn dispatch_action_any(
1092        &mut self,
1093        window_id: usize,
1094        path: &[usize],
1095        action: &dyn AnyAction,
1096    ) -> bool {
1097        self.update(|this| {
1098            let mut halted_dispatch = false;
1099            for view_id in path.iter().rev() {
1100                if let Some(mut view) = this.cx.views.remove(&(window_id, *view_id)) {
1101                    let type_id = view.as_any().type_id();
1102
1103                    if let Some((name, mut handlers)) = this
1104                        .actions
1105                        .get_mut(&type_id)
1106                        .and_then(|h| h.remove_entry(&action.id()))
1107                    {
1108                        for handler in handlers.iter_mut().rev() {
1109                            let halt_dispatch =
1110                                handler(view.as_mut(), action, this, window_id, *view_id);
1111                            if halt_dispatch {
1112                                halted_dispatch = true;
1113                                break;
1114                            }
1115                        }
1116                        this.actions
1117                            .get_mut(&type_id)
1118                            .unwrap()
1119                            .insert(name, handlers);
1120                    }
1121
1122                    this.cx.views.insert((window_id, *view_id), view);
1123
1124                    if halted_dispatch {
1125                        break;
1126                    }
1127                }
1128            }
1129
1130            if !halted_dispatch {
1131                halted_dispatch = this.dispatch_global_action_any(action);
1132            }
1133            halted_dispatch
1134        })
1135    }
1136
1137    pub fn dispatch_global_action<A: Action>(&mut self, action: A) {
1138        self.dispatch_global_action_any(&action);
1139    }
1140
1141    fn dispatch_global_action_any(&mut self, action: &dyn AnyAction) -> bool {
1142        self.update(|this| {
1143            if let Some((name, mut handler)) = this.global_actions.remove_entry(&action.id()) {
1144                handler(action, this);
1145                this.global_actions.insert(name, handler);
1146                true
1147            } else {
1148                false
1149            }
1150        })
1151    }
1152
1153    pub fn add_bindings<T: IntoIterator<Item = keymap::Binding>>(&mut self, bindings: T) {
1154        self.keystroke_matcher.add_bindings(bindings);
1155    }
1156
1157    pub fn dispatch_keystroke(
1158        &mut self,
1159        window_id: usize,
1160        responder_chain: Vec<usize>,
1161        keystroke: &Keystroke,
1162    ) -> Result<bool> {
1163        let mut context_chain = Vec::new();
1164        for view_id in &responder_chain {
1165            if let Some(view) = self.cx.views.get(&(window_id, *view_id)) {
1166                context_chain.push(view.keymap_context(self.as_ref()));
1167            } else {
1168                return Err(anyhow!(
1169                    "View {} in responder chain does not exist",
1170                    view_id
1171                ));
1172            }
1173        }
1174
1175        let mut pending = false;
1176        for (i, cx) in context_chain.iter().enumerate().rev() {
1177            match self
1178                .keystroke_matcher
1179                .push_keystroke(keystroke.clone(), responder_chain[i], cx)
1180            {
1181                MatchResult::None => {}
1182                MatchResult::Pending => pending = true,
1183                MatchResult::Action(action) => {
1184                    if self.dispatch_action_any(window_id, &responder_chain[0..=i], action.as_ref())
1185                    {
1186                        self.keystroke_matcher.clear_pending();
1187                        return Ok(true);
1188                    }
1189                }
1190            }
1191        }
1192
1193        Ok(pending)
1194    }
1195
1196    pub fn add_model<T, F>(&mut self, build_model: F) -> ModelHandle<T>
1197    where
1198        T: Entity,
1199        F: FnOnce(&mut ModelContext<T>) -> T,
1200    {
1201        self.update(|this| {
1202            let model_id = post_inc(&mut this.next_entity_id);
1203            let handle = ModelHandle::new(model_id, &this.cx.ref_counts);
1204            let mut cx = ModelContext::new(this, model_id);
1205            let model = build_model(&mut cx);
1206            this.cx.models.insert(model_id, Box::new(model));
1207            handle
1208        })
1209    }
1210
1211    pub fn add_window<T, F>(
1212        &mut self,
1213        window_options: WindowOptions,
1214        build_root_view: F,
1215    ) -> (usize, ViewHandle<T>)
1216    where
1217        T: View,
1218        F: FnOnce(&mut ViewContext<T>) -> T,
1219    {
1220        self.update(|this| {
1221            let window_id = post_inc(&mut this.next_window_id);
1222            let root_view = this.add_view(window_id, build_root_view);
1223
1224            this.cx.windows.insert(
1225                window_id,
1226                Window {
1227                    root_view: root_view.clone().into(),
1228                    focused_view_id: root_view.id(),
1229                    invalidation: None,
1230                },
1231            );
1232            this.open_platform_window(window_id, window_options);
1233            root_view.update(this, |view, cx| {
1234                view.on_focus(cx);
1235                cx.notify();
1236            });
1237
1238            (window_id, root_view)
1239        })
1240    }
1241
1242    pub fn remove_window(&mut self, window_id: usize) {
1243        self.cx.windows.remove(&window_id);
1244        self.presenters_and_platform_windows.remove(&window_id);
1245        self.remove_dropped_entities();
1246    }
1247
1248    fn open_platform_window(&mut self, window_id: usize, window_options: WindowOptions) {
1249        let mut window =
1250            self.cx
1251                .platform
1252                .open_window(window_id, window_options, self.foreground.clone());
1253        let presenter = Rc::new(RefCell::new(
1254            self.build_presenter(window_id, window.titlebar_height()),
1255        ));
1256
1257        {
1258            let mut app = self.upgrade();
1259            let presenter = presenter.clone();
1260            window.on_event(Box::new(move |event| {
1261                app.update(|cx| {
1262                    if let Event::KeyDown { keystroke, .. } = &event {
1263                        if cx
1264                            .dispatch_keystroke(
1265                                window_id,
1266                                presenter.borrow().dispatch_path(cx.as_ref()),
1267                                keystroke,
1268                            )
1269                            .unwrap()
1270                        {
1271                            return;
1272                        }
1273                    }
1274
1275                    presenter.borrow_mut().dispatch_event(event, cx);
1276                })
1277            }));
1278        }
1279
1280        {
1281            let mut app = self.upgrade();
1282            window.on_resize(Box::new(move || {
1283                app.update(|cx| cx.resize_window(window_id))
1284            }));
1285        }
1286
1287        {
1288            let mut app = self.upgrade();
1289            window.on_close(Box::new(move || {
1290                app.update(|cx| cx.remove_window(window_id));
1291            }));
1292        }
1293
1294        self.presenters_and_platform_windows
1295            .insert(window_id, (presenter.clone(), window));
1296
1297        self.on_debug_elements(window_id, move |cx| {
1298            presenter.borrow().debug_elements(cx).unwrap()
1299        });
1300    }
1301
1302    pub fn build_presenter(&mut self, window_id: usize, titlebar_height: f32) -> Presenter {
1303        Presenter::new(
1304            window_id,
1305            titlebar_height,
1306            self.cx.font_cache.clone(),
1307            TextLayoutCache::new(self.cx.platform.fonts()),
1308            self.assets.clone(),
1309            self,
1310        )
1311    }
1312
1313    pub fn build_render_context<V: View>(
1314        &mut self,
1315        window_id: usize,
1316        view_id: usize,
1317        titlebar_height: f32,
1318        refreshing: bool,
1319    ) -> RenderContext<V> {
1320        RenderContext {
1321            app: self,
1322            titlebar_height,
1323            refreshing,
1324            window_id,
1325            view_id,
1326            view_type: PhantomData,
1327        }
1328    }
1329
1330    pub fn add_view<T, F>(&mut self, window_id: usize, build_view: F) -> ViewHandle<T>
1331    where
1332        T: View,
1333        F: FnOnce(&mut ViewContext<T>) -> T,
1334    {
1335        self.add_option_view(window_id, |cx| Some(build_view(cx)))
1336            .unwrap()
1337    }
1338
1339    pub fn add_option_view<T, F>(
1340        &mut self,
1341        window_id: usize,
1342        build_view: F,
1343    ) -> Option<ViewHandle<T>>
1344    where
1345        T: View,
1346        F: FnOnce(&mut ViewContext<T>) -> Option<T>,
1347    {
1348        self.update(|this| {
1349            let view_id = post_inc(&mut this.next_entity_id);
1350            let mut cx = ViewContext::new(this, window_id, view_id);
1351            let handle = if let Some(view) = build_view(&mut cx) {
1352                this.cx.views.insert((window_id, view_id), Box::new(view));
1353                if let Some(window) = this.cx.windows.get_mut(&window_id) {
1354                    window
1355                        .invalidation
1356                        .get_or_insert_with(Default::default)
1357                        .updated
1358                        .insert(view_id);
1359                }
1360                Some(ViewHandle::new(window_id, view_id, &this.cx.ref_counts))
1361            } else {
1362                None
1363            };
1364            handle
1365        })
1366    }
1367
1368    pub fn element_state<Tag: 'static, T: 'static + Default>(
1369        &mut self,
1370        id: ElementStateId,
1371    ) -> ElementStateHandle<T> {
1372        let key = (TypeId::of::<Tag>(), id);
1373        self.cx
1374            .element_states
1375            .entry(key)
1376            .or_insert_with(|| Box::new(T::default()));
1377        ElementStateHandle::new(TypeId::of::<Tag>(), id, &self.cx.ref_counts)
1378    }
1379
1380    fn remove_dropped_entities(&mut self) {
1381        loop {
1382            let (dropped_models, dropped_views, dropped_element_states) =
1383                self.cx.ref_counts.lock().take_dropped();
1384            if dropped_models.is_empty()
1385                && dropped_views.is_empty()
1386                && dropped_element_states.is_empty()
1387            {
1388                break;
1389            }
1390
1391            for model_id in dropped_models {
1392                self.subscriptions.lock().remove(&model_id);
1393                self.observations.lock().remove(&model_id);
1394                let mut model = self.cx.models.remove(&model_id).unwrap();
1395                model.release(self);
1396            }
1397
1398            for (window_id, view_id) in dropped_views {
1399                self.subscriptions.lock().remove(&view_id);
1400                self.observations.lock().remove(&view_id);
1401                let mut view = self.cx.views.remove(&(window_id, view_id)).unwrap();
1402                view.release(self);
1403                let change_focus_to = self.cx.windows.get_mut(&window_id).and_then(|window| {
1404                    window
1405                        .invalidation
1406                        .get_or_insert_with(Default::default)
1407                        .removed
1408                        .push(view_id);
1409                    if window.focused_view_id == view_id {
1410                        Some(window.root_view.id())
1411                    } else {
1412                        None
1413                    }
1414                });
1415
1416                if let Some(view_id) = change_focus_to {
1417                    self.focus(window_id, view_id);
1418                }
1419            }
1420
1421            for key in dropped_element_states {
1422                self.cx.element_states.remove(&key);
1423            }
1424        }
1425    }
1426
1427    fn flush_effects(&mut self) {
1428        self.pending_flushes = self.pending_flushes.saturating_sub(1);
1429
1430        if !self.flushing_effects && self.pending_flushes == 0 {
1431            self.flushing_effects = true;
1432
1433            let mut refreshing = false;
1434            loop {
1435                if let Some(effect) = self.pending_effects.pop_front() {
1436                    match effect {
1437                        Effect::Event { entity_id, payload } => self.emit_event(entity_id, payload),
1438                        Effect::ModelNotification { model_id } => {
1439                            self.notify_model_observers(model_id)
1440                        }
1441                        Effect::ViewNotification { window_id, view_id } => {
1442                            self.notify_view_observers(window_id, view_id)
1443                        }
1444                        Effect::Focus { window_id, view_id } => {
1445                            self.focus(window_id, view_id);
1446                        }
1447                        Effect::ResizeWindow { window_id } => {
1448                            if let Some(window) = self.cx.windows.get_mut(&window_id) {
1449                                window
1450                                    .invalidation
1451                                    .get_or_insert(WindowInvalidation::default());
1452                            }
1453                        }
1454                        Effect::RefreshWindows => {
1455                            refreshing = true;
1456                        }
1457                    }
1458                    self.pending_notifications.clear();
1459                    self.remove_dropped_entities();
1460                } else {
1461                    self.remove_dropped_entities();
1462                    if refreshing {
1463                        self.perform_window_refresh();
1464                    } else {
1465                        self.update_windows();
1466                    }
1467
1468                    if self.pending_effects.is_empty() {
1469                        self.flushing_effects = false;
1470                        self.pending_notifications.clear();
1471                        break;
1472                    } else {
1473                        refreshing = false;
1474                    }
1475                }
1476            }
1477        }
1478    }
1479
1480    fn update_windows(&mut self) {
1481        let mut invalidations = HashMap::new();
1482        for (window_id, window) in &mut self.cx.windows {
1483            if let Some(invalidation) = window.invalidation.take() {
1484                invalidations.insert(*window_id, invalidation);
1485            }
1486        }
1487
1488        for (window_id, invalidation) in invalidations {
1489            if let Some((presenter, mut window)) =
1490                self.presenters_and_platform_windows.remove(&window_id)
1491            {
1492                {
1493                    let mut presenter = presenter.borrow_mut();
1494                    presenter.invalidate(invalidation, self);
1495                    let scene =
1496                        presenter.build_scene(window.size(), window.scale_factor(), false, self);
1497                    window.present_scene(scene);
1498                }
1499                self.presenters_and_platform_windows
1500                    .insert(window_id, (presenter, window));
1501            }
1502        }
1503    }
1504
1505    fn resize_window(&mut self, window_id: usize) {
1506        self.pending_effects
1507            .push_back(Effect::ResizeWindow { window_id });
1508    }
1509
1510    pub fn refresh_windows(&mut self) {
1511        self.pending_effects.push_back(Effect::RefreshWindows);
1512    }
1513
1514    fn perform_window_refresh(&mut self) {
1515        let mut presenters = mem::take(&mut self.presenters_and_platform_windows);
1516        for (window_id, (presenter, window)) in &mut presenters {
1517            let invalidation = self
1518                .cx
1519                .windows
1520                .get_mut(&window_id)
1521                .unwrap()
1522                .invalidation
1523                .take();
1524            let mut presenter = presenter.borrow_mut();
1525            presenter.refresh(invalidation, self);
1526            let scene = presenter.build_scene(window.size(), window.scale_factor(), true, self);
1527            window.present_scene(scene);
1528        }
1529        self.presenters_and_platform_windows = presenters;
1530    }
1531
1532    pub fn set_cursor_style(&mut self, style: CursorStyle) -> CursorStyleHandle {
1533        self.platform.set_cursor_style(style);
1534        let id = self.next_cursor_style_handle_id.fetch_add(1, SeqCst);
1535        CursorStyleHandle {
1536            id,
1537            next_cursor_style_handle_id: self.next_cursor_style_handle_id.clone(),
1538            platform: self.platform(),
1539        }
1540    }
1541
1542    fn emit_event(&mut self, entity_id: usize, payload: Box<dyn Any>) {
1543        let callbacks = self.subscriptions.lock().remove(&entity_id);
1544        if let Some(callbacks) = callbacks {
1545            for (id, mut callback) in callbacks {
1546                let alive = callback(payload.as_ref(), self);
1547                if alive {
1548                    self.subscriptions
1549                        .lock()
1550                        .entry(entity_id)
1551                        .or_default()
1552                        .insert(id, callback);
1553                }
1554            }
1555        }
1556    }
1557
1558    fn notify_model_observers(&mut self, observed_id: usize) {
1559        let callbacks = self.observations.lock().remove(&observed_id);
1560        if let Some(callbacks) = callbacks {
1561            if self.cx.models.contains_key(&observed_id) {
1562                for (id, mut callback) in callbacks {
1563                    let alive = callback(self);
1564                    if alive {
1565                        self.observations
1566                            .lock()
1567                            .entry(observed_id)
1568                            .or_default()
1569                            .insert(id, callback);
1570                    }
1571                }
1572            }
1573        }
1574    }
1575
1576    fn notify_view_observers(&mut self, observed_window_id: usize, observed_view_id: usize) {
1577        if let Some(window) = self.cx.windows.get_mut(&observed_window_id) {
1578            window
1579                .invalidation
1580                .get_or_insert_with(Default::default)
1581                .updated
1582                .insert(observed_view_id);
1583        }
1584
1585        let callbacks = self.observations.lock().remove(&observed_view_id);
1586        if let Some(callbacks) = callbacks {
1587            if self
1588                .cx
1589                .views
1590                .contains_key(&(observed_window_id, observed_view_id))
1591            {
1592                for (id, mut callback) in callbacks {
1593                    let alive = callback(self);
1594                    if alive {
1595                        self.observations
1596                            .lock()
1597                            .entry(observed_view_id)
1598                            .or_default()
1599                            .insert(id, callback);
1600                    }
1601                }
1602            }
1603        }
1604    }
1605
1606    fn focus(&mut self, window_id: usize, focused_id: usize) {
1607        if self
1608            .cx
1609            .windows
1610            .get(&window_id)
1611            .map(|w| w.focused_view_id)
1612            .map_or(false, |cur_focused| cur_focused == focused_id)
1613        {
1614            return;
1615        }
1616
1617        self.update(|this| {
1618            let blurred_id = this.cx.windows.get_mut(&window_id).map(|window| {
1619                let blurred_id = window.focused_view_id;
1620                window.focused_view_id = focused_id;
1621                blurred_id
1622            });
1623
1624            if let Some(blurred_id) = blurred_id {
1625                if let Some(mut blurred_view) = this.cx.views.remove(&(window_id, blurred_id)) {
1626                    blurred_view.on_blur(this, window_id, blurred_id);
1627                    this.cx.views.insert((window_id, blurred_id), blurred_view);
1628                }
1629            }
1630
1631            if let Some(mut focused_view) = this.cx.views.remove(&(window_id, focused_id)) {
1632                focused_view.on_focus(this, window_id, focused_id);
1633                this.cx.views.insert((window_id, focused_id), focused_view);
1634            }
1635        })
1636    }
1637
1638    pub fn spawn<F, Fut, T>(&self, f: F) -> Task<T>
1639    where
1640        F: FnOnce(AsyncAppContext) -> Fut,
1641        Fut: 'static + Future<Output = T>,
1642        T: 'static,
1643    {
1644        let cx = self.to_async();
1645        self.foreground.spawn(f(cx))
1646    }
1647
1648    pub fn to_async(&self) -> AsyncAppContext {
1649        AsyncAppContext(self.weak_self.as_ref().unwrap().upgrade().unwrap())
1650    }
1651
1652    pub fn write_to_clipboard(&self, item: ClipboardItem) {
1653        self.cx.platform.write_to_clipboard(item);
1654    }
1655
1656    pub fn read_from_clipboard(&self) -> Option<ClipboardItem> {
1657        self.cx.platform.read_from_clipboard()
1658    }
1659}
1660
1661impl ReadModel for MutableAppContext {
1662    fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T {
1663        if let Some(model) = self.cx.models.get(&handle.model_id) {
1664            model
1665                .as_any()
1666                .downcast_ref()
1667                .expect("downcast is type safe")
1668        } else {
1669            panic!("circular model reference");
1670        }
1671    }
1672}
1673
1674impl UpdateModel for MutableAppContext {
1675    fn update_model<T: Entity, V>(
1676        &mut self,
1677        handle: &ModelHandle<T>,
1678        update: &mut dyn FnMut(&mut T, &mut ModelContext<T>) -> V,
1679    ) -> V {
1680        if let Some(mut model) = self.cx.models.remove(&handle.model_id) {
1681            self.update(|this| {
1682                let mut cx = ModelContext::new(this, handle.model_id);
1683                let result = update(
1684                    model
1685                        .as_any_mut()
1686                        .downcast_mut()
1687                        .expect("downcast is type safe"),
1688                    &mut cx,
1689                );
1690                this.cx.models.insert(handle.model_id, model);
1691                result
1692            })
1693        } else {
1694            panic!("circular model update");
1695        }
1696    }
1697}
1698
1699impl UpgradeModelHandle for MutableAppContext {
1700    fn upgrade_model_handle<T: Entity>(
1701        &self,
1702        handle: WeakModelHandle<T>,
1703    ) -> Option<ModelHandle<T>> {
1704        self.cx.upgrade_model_handle(handle)
1705    }
1706}
1707
1708impl ReadView for MutableAppContext {
1709    fn read_view<T: View>(&self, handle: &ViewHandle<T>) -> &T {
1710        if let Some(view) = self.cx.views.get(&(handle.window_id, handle.view_id)) {
1711            view.as_any().downcast_ref().expect("downcast is type safe")
1712        } else {
1713            panic!("circular view reference");
1714        }
1715    }
1716}
1717
1718impl UpdateView for MutableAppContext {
1719    fn update_view<T, S>(
1720        &mut self,
1721        handle: &ViewHandle<T>,
1722        update: &mut dyn FnMut(&mut T, &mut ViewContext<T>) -> S,
1723    ) -> S
1724    where
1725        T: View,
1726    {
1727        self.update(|this| {
1728            let mut view = this
1729                .cx
1730                .views
1731                .remove(&(handle.window_id, handle.view_id))
1732                .expect("circular view update");
1733
1734            let mut cx = ViewContext::new(this, handle.window_id, handle.view_id);
1735            let result = update(
1736                view.as_any_mut()
1737                    .downcast_mut()
1738                    .expect("downcast is type safe"),
1739                &mut cx,
1740            );
1741            this.cx
1742                .views
1743                .insert((handle.window_id, handle.view_id), view);
1744            result
1745        })
1746    }
1747}
1748
1749impl AsRef<AppContext> for MutableAppContext {
1750    fn as_ref(&self) -> &AppContext {
1751        &self.cx
1752    }
1753}
1754
1755impl Deref for MutableAppContext {
1756    type Target = AppContext;
1757
1758    fn deref(&self) -> &Self::Target {
1759        &self.cx
1760    }
1761}
1762
1763pub struct AppContext {
1764    models: HashMap<usize, Box<dyn AnyModel>>,
1765    views: HashMap<(usize, usize), Box<dyn AnyView>>,
1766    windows: HashMap<usize, Window>,
1767    element_states: HashMap<(TypeId, ElementStateId), Box<dyn Any>>,
1768    background: Arc<executor::Background>,
1769    ref_counts: Arc<Mutex<RefCounts>>,
1770    font_cache: Arc<FontCache>,
1771    platform: Arc<dyn Platform>,
1772}
1773
1774impl AppContext {
1775    pub fn root_view_id(&self, window_id: usize) -> Option<usize> {
1776        self.windows
1777            .get(&window_id)
1778            .map(|window| window.root_view.id())
1779    }
1780
1781    pub fn focused_view_id(&self, window_id: usize) -> Option<usize> {
1782        self.windows
1783            .get(&window_id)
1784            .map(|window| window.focused_view_id)
1785    }
1786
1787    pub fn background(&self) -> &Arc<executor::Background> {
1788        &self.background
1789    }
1790
1791    pub fn font_cache(&self) -> &Arc<FontCache> {
1792        &self.font_cache
1793    }
1794
1795    pub fn platform(&self) -> &Arc<dyn Platform> {
1796        &self.platform
1797    }
1798}
1799
1800impl ReadModel for AppContext {
1801    fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T {
1802        if let Some(model) = self.models.get(&handle.model_id) {
1803            model
1804                .as_any()
1805                .downcast_ref()
1806                .expect("downcast should be type safe")
1807        } else {
1808            panic!("circular model reference");
1809        }
1810    }
1811}
1812
1813impl UpgradeModelHandle for AppContext {
1814    fn upgrade_model_handle<T: Entity>(
1815        &self,
1816        handle: WeakModelHandle<T>,
1817    ) -> Option<ModelHandle<T>> {
1818        if self.models.contains_key(&handle.model_id) {
1819            Some(ModelHandle::new(handle.model_id, &self.ref_counts))
1820        } else {
1821            None
1822        }
1823    }
1824}
1825
1826impl ReadView for AppContext {
1827    fn read_view<T: View>(&self, handle: &ViewHandle<T>) -> &T {
1828        if let Some(view) = self.views.get(&(handle.window_id, handle.view_id)) {
1829            view.as_any()
1830                .downcast_ref()
1831                .expect("downcast should be type safe")
1832        } else {
1833            panic!("circular view reference");
1834        }
1835    }
1836}
1837
1838struct Window {
1839    root_view: AnyViewHandle,
1840    focused_view_id: usize,
1841    invalidation: Option<WindowInvalidation>,
1842}
1843
1844#[derive(Default, Clone)]
1845pub struct WindowInvalidation {
1846    pub updated: HashSet<usize>,
1847    pub removed: Vec<usize>,
1848}
1849
1850pub enum Effect {
1851    Event {
1852        entity_id: usize,
1853        payload: Box<dyn Any>,
1854    },
1855    ModelNotification {
1856        model_id: usize,
1857    },
1858    ViewNotification {
1859        window_id: usize,
1860        view_id: usize,
1861    },
1862    Focus {
1863        window_id: usize,
1864        view_id: usize,
1865    },
1866    ResizeWindow {
1867        window_id: usize,
1868    },
1869    RefreshWindows,
1870}
1871
1872impl Debug for Effect {
1873    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1874        match self {
1875            Effect::Event { entity_id, .. } => f
1876                .debug_struct("Effect::Event")
1877                .field("entity_id", entity_id)
1878                .finish(),
1879            Effect::ModelNotification { model_id } => f
1880                .debug_struct("Effect::ModelNotification")
1881                .field("model_id", model_id)
1882                .finish(),
1883            Effect::ViewNotification { window_id, view_id } => f
1884                .debug_struct("Effect::ViewNotification")
1885                .field("window_id", window_id)
1886                .field("view_id", view_id)
1887                .finish(),
1888            Effect::Focus { window_id, view_id } => f
1889                .debug_struct("Effect::Focus")
1890                .field("window_id", window_id)
1891                .field("view_id", view_id)
1892                .finish(),
1893            Effect::ResizeWindow { window_id } => f
1894                .debug_struct("Effect::RefreshWindow")
1895                .field("window_id", window_id)
1896                .finish(),
1897            Effect::RefreshWindows => f.debug_struct("Effect::FullViewRefresh").finish(),
1898        }
1899    }
1900}
1901
1902pub trait AnyModel {
1903    fn as_any(&self) -> &dyn Any;
1904    fn as_any_mut(&mut self) -> &mut dyn Any;
1905    fn release(&mut self, cx: &mut MutableAppContext);
1906    fn app_will_quit(
1907        &mut self,
1908        cx: &mut MutableAppContext,
1909    ) -> Option<Pin<Box<dyn 'static + Future<Output = ()>>>>;
1910}
1911
1912impl<T> AnyModel for T
1913where
1914    T: Entity,
1915{
1916    fn as_any(&self) -> &dyn Any {
1917        self
1918    }
1919
1920    fn as_any_mut(&mut self) -> &mut dyn Any {
1921        self
1922    }
1923
1924    fn release(&mut self, cx: &mut MutableAppContext) {
1925        self.release(cx);
1926    }
1927
1928    fn app_will_quit(
1929        &mut self,
1930        cx: &mut MutableAppContext,
1931    ) -> Option<Pin<Box<dyn 'static + Future<Output = ()>>>> {
1932        self.app_will_quit(cx)
1933    }
1934}
1935
1936pub trait AnyView {
1937    fn as_any(&self) -> &dyn Any;
1938    fn as_any_mut(&mut self) -> &mut dyn Any;
1939    fn release(&mut self, cx: &mut MutableAppContext);
1940    fn app_will_quit(
1941        &mut self,
1942        cx: &mut MutableAppContext,
1943    ) -> Option<Pin<Box<dyn 'static + Future<Output = ()>>>>;
1944    fn ui_name(&self) -> &'static str;
1945    fn render<'a>(
1946        &mut self,
1947        window_id: usize,
1948        view_id: usize,
1949        titlebar_height: f32,
1950        refreshing: bool,
1951        cx: &mut MutableAppContext,
1952    ) -> ElementBox;
1953    fn on_focus(&mut self, cx: &mut MutableAppContext, window_id: usize, view_id: usize);
1954    fn on_blur(&mut self, cx: &mut MutableAppContext, window_id: usize, view_id: usize);
1955    fn keymap_context(&self, cx: &AppContext) -> keymap::Context;
1956}
1957
1958impl<T> AnyView for T
1959where
1960    T: View,
1961{
1962    fn as_any(&self) -> &dyn Any {
1963        self
1964    }
1965
1966    fn as_any_mut(&mut self) -> &mut dyn Any {
1967        self
1968    }
1969
1970    fn release(&mut self, cx: &mut MutableAppContext) {
1971        self.release(cx);
1972    }
1973
1974    fn app_will_quit(
1975        &mut self,
1976        cx: &mut MutableAppContext,
1977    ) -> Option<Pin<Box<dyn 'static + Future<Output = ()>>>> {
1978        self.app_will_quit(cx)
1979    }
1980
1981    fn ui_name(&self) -> &'static str {
1982        T::ui_name()
1983    }
1984
1985    fn render<'a>(
1986        &mut self,
1987        window_id: usize,
1988        view_id: usize,
1989        titlebar_height: f32,
1990        refreshing: bool,
1991        cx: &mut MutableAppContext,
1992    ) -> ElementBox {
1993        View::render(
1994            self,
1995            &mut RenderContext {
1996                window_id,
1997                view_id,
1998                app: cx,
1999                view_type: PhantomData::<T>,
2000                titlebar_height,
2001                refreshing,
2002            },
2003        )
2004    }
2005
2006    fn on_focus(&mut self, cx: &mut MutableAppContext, window_id: usize, view_id: usize) {
2007        let mut cx = ViewContext::new(cx, window_id, view_id);
2008        View::on_focus(self, &mut cx);
2009    }
2010
2011    fn on_blur(&mut self, cx: &mut MutableAppContext, window_id: usize, view_id: usize) {
2012        let mut cx = ViewContext::new(cx, window_id, view_id);
2013        View::on_blur(self, &mut cx);
2014    }
2015
2016    fn keymap_context(&self, cx: &AppContext) -> keymap::Context {
2017        View::keymap_context(self, cx)
2018    }
2019}
2020
2021pub struct ModelContext<'a, T: ?Sized> {
2022    app: &'a mut MutableAppContext,
2023    model_id: usize,
2024    model_type: PhantomData<T>,
2025    halt_stream: bool,
2026}
2027
2028impl<'a, T: Entity> ModelContext<'a, T> {
2029    fn new(app: &'a mut MutableAppContext, model_id: usize) -> Self {
2030        Self {
2031            app,
2032            model_id,
2033            model_type: PhantomData,
2034            halt_stream: false,
2035        }
2036    }
2037
2038    pub fn background(&self) -> &Arc<executor::Background> {
2039        &self.app.cx.background
2040    }
2041
2042    pub fn halt_stream(&mut self) {
2043        self.halt_stream = true;
2044    }
2045
2046    pub fn model_id(&self) -> usize {
2047        self.model_id
2048    }
2049
2050    pub fn add_model<S, F>(&mut self, build_model: F) -> ModelHandle<S>
2051    where
2052        S: Entity,
2053        F: FnOnce(&mut ModelContext<S>) -> S,
2054    {
2055        self.app.add_model(build_model)
2056    }
2057
2058    pub fn emit(&mut self, payload: T::Event) {
2059        self.app.pending_effects.push_back(Effect::Event {
2060            entity_id: self.model_id,
2061            payload: Box::new(payload),
2062        });
2063    }
2064
2065    pub fn notify(&mut self) {
2066        self.app.notify_model(self.model_id);
2067    }
2068
2069    pub fn subscribe<S: Entity, F>(
2070        &mut self,
2071        handle: &ModelHandle<S>,
2072        mut callback: F,
2073    ) -> Subscription
2074    where
2075        S::Event: 'static,
2076        F: 'static + FnMut(&mut T, ModelHandle<S>, &S::Event, &mut ModelContext<T>),
2077    {
2078        let subscriber = self.weak_handle();
2079        self.app
2080            .subscribe_internal(handle, move |emitter, event, cx| {
2081                if let Some(subscriber) = subscriber.upgrade(cx) {
2082                    subscriber.update(cx, |subscriber, cx| {
2083                        callback(subscriber, emitter, event, cx);
2084                    });
2085                    true
2086                } else {
2087                    false
2088                }
2089            })
2090    }
2091
2092    pub fn observe<S, F>(&mut self, handle: &ModelHandle<S>, mut callback: F) -> Subscription
2093    where
2094        S: Entity,
2095        F: 'static + FnMut(&mut T, ModelHandle<S>, &mut ModelContext<T>),
2096    {
2097        let observer = self.weak_handle();
2098        self.app.observe_internal(handle, move |observed, cx| {
2099            if let Some(observer) = observer.upgrade(cx) {
2100                observer.update(cx, |observer, cx| {
2101                    callback(observer, observed, cx);
2102                });
2103                true
2104            } else {
2105                false
2106            }
2107        })
2108    }
2109
2110    pub fn handle(&self) -> ModelHandle<T> {
2111        ModelHandle::new(self.model_id, &self.app.cx.ref_counts)
2112    }
2113
2114    pub fn weak_handle(&self) -> WeakModelHandle<T> {
2115        WeakModelHandle::new(self.model_id)
2116    }
2117
2118    pub fn spawn<F, Fut, S>(&self, f: F) -> Task<S>
2119    where
2120        F: FnOnce(ModelHandle<T>, AsyncAppContext) -> Fut,
2121        Fut: 'static + Future<Output = S>,
2122        S: 'static,
2123    {
2124        let handle = self.handle();
2125        self.app.spawn(|cx| f(handle, cx))
2126    }
2127
2128    pub fn spawn_weak<F, Fut, S>(&self, f: F) -> Task<S>
2129    where
2130        F: FnOnce(WeakModelHandle<T>, AsyncAppContext) -> Fut,
2131        Fut: 'static + Future<Output = S>,
2132        S: 'static,
2133    {
2134        let handle = self.weak_handle();
2135        self.app.spawn(|cx| f(handle, cx))
2136    }
2137}
2138
2139impl<M> AsRef<AppContext> for ModelContext<'_, M> {
2140    fn as_ref(&self) -> &AppContext {
2141        &self.app.cx
2142    }
2143}
2144
2145impl<M> AsMut<MutableAppContext> for ModelContext<'_, M> {
2146    fn as_mut(&mut self) -> &mut MutableAppContext {
2147        self.app
2148    }
2149}
2150
2151impl<M> ReadModel for ModelContext<'_, M> {
2152    fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T {
2153        self.app.read_model(handle)
2154    }
2155}
2156
2157impl<M> UpdateModel for ModelContext<'_, M> {
2158    fn update_model<T: Entity, V>(
2159        &mut self,
2160        handle: &ModelHandle<T>,
2161        update: &mut dyn FnMut(&mut T, &mut ModelContext<T>) -> V,
2162    ) -> V {
2163        self.app.update_model(handle, update)
2164    }
2165}
2166
2167impl<M> UpgradeModelHandle for ModelContext<'_, M> {
2168    fn upgrade_model_handle<T: Entity>(
2169        &self,
2170        handle: WeakModelHandle<T>,
2171    ) -> Option<ModelHandle<T>> {
2172        self.cx.upgrade_model_handle(handle)
2173    }
2174}
2175
2176impl<M> Deref for ModelContext<'_, M> {
2177    type Target = MutableAppContext;
2178
2179    fn deref(&self) -> &Self::Target {
2180        &self.app
2181    }
2182}
2183
2184impl<M> DerefMut for ModelContext<'_, M> {
2185    fn deref_mut(&mut self) -> &mut Self::Target {
2186        &mut self.app
2187    }
2188}
2189
2190pub struct ViewContext<'a, T: ?Sized> {
2191    app: &'a mut MutableAppContext,
2192    window_id: usize,
2193    view_id: usize,
2194    view_type: PhantomData<T>,
2195    halt_action_dispatch: bool,
2196}
2197
2198impl<'a, T: View> ViewContext<'a, T> {
2199    fn new(app: &'a mut MutableAppContext, window_id: usize, view_id: usize) -> Self {
2200        Self {
2201            app,
2202            window_id,
2203            view_id,
2204            view_type: PhantomData,
2205            halt_action_dispatch: true,
2206        }
2207    }
2208
2209    pub fn handle(&self) -> ViewHandle<T> {
2210        ViewHandle::new(self.window_id, self.view_id, &self.app.cx.ref_counts)
2211    }
2212
2213    pub fn weak_handle(&self) -> WeakViewHandle<T> {
2214        WeakViewHandle::new(self.window_id, self.view_id)
2215    }
2216
2217    pub fn window_id(&self) -> usize {
2218        self.window_id
2219    }
2220
2221    pub fn view_id(&self) -> usize {
2222        self.view_id
2223    }
2224
2225    pub fn foreground(&self) -> &Rc<executor::Foreground> {
2226        self.app.foreground()
2227    }
2228
2229    pub fn background_executor(&self) -> &Arc<executor::Background> {
2230        &self.app.cx.background
2231    }
2232
2233    pub fn platform(&self) -> Arc<dyn Platform> {
2234        self.app.platform()
2235    }
2236
2237    pub fn prompt<F>(&self, level: PromptLevel, msg: &str, answers: &[&str], done_fn: F)
2238    where
2239        F: 'static + FnOnce(usize, &mut MutableAppContext),
2240    {
2241        self.app
2242            .prompt(self.window_id, level, msg, answers, done_fn)
2243    }
2244
2245    pub fn prompt_for_paths<F>(&self, options: PathPromptOptions, done_fn: F)
2246    where
2247        F: 'static + FnOnce(Option<Vec<PathBuf>>, &mut MutableAppContext),
2248    {
2249        self.app.prompt_for_paths(options, done_fn)
2250    }
2251
2252    pub fn prompt_for_new_path<F>(&self, directory: &Path, done_fn: F)
2253    where
2254        F: 'static + FnOnce(Option<PathBuf>, &mut MutableAppContext),
2255    {
2256        self.app.prompt_for_new_path(directory, done_fn)
2257    }
2258
2259    pub fn debug_elements(&self) -> crate::json::Value {
2260        self.app.debug_elements(self.window_id).unwrap()
2261    }
2262
2263    pub fn focus<S>(&mut self, handle: S)
2264    where
2265        S: Into<AnyViewHandle>,
2266    {
2267        let handle = handle.into();
2268        self.app.pending_effects.push_back(Effect::Focus {
2269            window_id: handle.window_id,
2270            view_id: handle.view_id,
2271        });
2272    }
2273
2274    pub fn focus_self(&mut self) {
2275        self.app.pending_effects.push_back(Effect::Focus {
2276            window_id: self.window_id,
2277            view_id: self.view_id,
2278        });
2279    }
2280
2281    pub fn add_model<S, F>(&mut self, build_model: F) -> ModelHandle<S>
2282    where
2283        S: Entity,
2284        F: FnOnce(&mut ModelContext<S>) -> S,
2285    {
2286        self.app.add_model(build_model)
2287    }
2288
2289    pub fn add_view<S, F>(&mut self, build_view: F) -> ViewHandle<S>
2290    where
2291        S: View,
2292        F: FnOnce(&mut ViewContext<S>) -> S,
2293    {
2294        self.app.add_view(self.window_id, build_view)
2295    }
2296
2297    pub fn add_option_view<S, F>(&mut self, build_view: F) -> Option<ViewHandle<S>>
2298    where
2299        S: View,
2300        F: FnOnce(&mut ViewContext<S>) -> Option<S>,
2301    {
2302        self.app.add_option_view(self.window_id, build_view)
2303    }
2304
2305    pub fn subscribe<E, H, F>(&mut self, handle: &H, mut callback: F) -> Subscription
2306    where
2307        E: Entity,
2308        E::Event: 'static,
2309        H: Handle<E>,
2310        F: 'static + FnMut(&mut T, H, &E::Event, &mut ViewContext<T>),
2311    {
2312        let subscriber = self.weak_handle();
2313        self.app
2314            .subscribe_internal(handle, move |emitter, event, cx| {
2315                if let Some(subscriber) = subscriber.upgrade(cx) {
2316                    subscriber.update(cx, |subscriber, cx| {
2317                        callback(subscriber, emitter, event, cx);
2318                    });
2319                    true
2320                } else {
2321                    false
2322                }
2323            })
2324    }
2325
2326    pub fn observe<E, F, H>(&mut self, handle: &H, mut callback: F) -> Subscription
2327    where
2328        E: Entity,
2329        H: Handle<E>,
2330        F: 'static + FnMut(&mut T, H, &mut ViewContext<T>),
2331    {
2332        let observer = self.weak_handle();
2333        self.app.observe_internal(handle, move |observed, cx| {
2334            if let Some(observer) = observer.upgrade(cx) {
2335                observer.update(cx, |observer, cx| {
2336                    callback(observer, observed, cx);
2337                });
2338                true
2339            } else {
2340                false
2341            }
2342        })
2343    }
2344
2345    pub fn emit(&mut self, payload: T::Event) {
2346        self.app.pending_effects.push_back(Effect::Event {
2347            entity_id: self.view_id,
2348            payload: Box::new(payload),
2349        });
2350    }
2351
2352    pub fn notify(&mut self) {
2353        self.app.notify_view(self.window_id, self.view_id);
2354    }
2355
2356    pub fn propagate_action(&mut self) {
2357        self.halt_action_dispatch = false;
2358    }
2359
2360    pub fn spawn<F, Fut, S>(&self, f: F) -> Task<S>
2361    where
2362        F: FnOnce(ViewHandle<T>, AsyncAppContext) -> Fut,
2363        Fut: 'static + Future<Output = S>,
2364        S: 'static,
2365    {
2366        let handle = self.handle();
2367        self.app.spawn(|cx| f(handle, cx))
2368    }
2369
2370    pub fn spawn_weak<F, Fut, S>(&self, f: F) -> Task<S>
2371    where
2372        F: FnOnce(WeakViewHandle<T>, AsyncAppContext) -> Fut,
2373        Fut: 'static + Future<Output = S>,
2374        S: 'static,
2375    {
2376        let handle = self.weak_handle();
2377        self.app.spawn(|cx| f(handle, cx))
2378    }
2379}
2380
2381pub struct RenderContext<'a, T: View> {
2382    pub app: &'a mut MutableAppContext,
2383    pub titlebar_height: f32,
2384    pub refreshing: bool,
2385    window_id: usize,
2386    view_id: usize,
2387    view_type: PhantomData<T>,
2388}
2389
2390impl<'a, T: View> RenderContext<'a, T> {
2391    pub fn handle(&self) -> WeakViewHandle<T> {
2392        WeakViewHandle::new(self.window_id, self.view_id)
2393    }
2394
2395    pub fn view_id(&self) -> usize {
2396        self.view_id
2397    }
2398}
2399
2400impl AsRef<AppContext> for &AppContext {
2401    fn as_ref(&self) -> &AppContext {
2402        self
2403    }
2404}
2405
2406impl<V: View> Deref for RenderContext<'_, V> {
2407    type Target = MutableAppContext;
2408
2409    fn deref(&self) -> &Self::Target {
2410        self.app
2411    }
2412}
2413
2414impl<V: View> DerefMut for RenderContext<'_, V> {
2415    fn deref_mut(&mut self) -> &mut Self::Target {
2416        self.app
2417    }
2418}
2419
2420impl<V: View> ReadModel for RenderContext<'_, V> {
2421    fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T {
2422        self.app.read_model(handle)
2423    }
2424}
2425
2426impl<V: View> UpdateModel for RenderContext<'_, V> {
2427    fn update_model<T: Entity, O>(
2428        &mut self,
2429        handle: &ModelHandle<T>,
2430        update: &mut dyn FnMut(&mut T, &mut ModelContext<T>) -> O,
2431    ) -> O {
2432        self.app.update_model(handle, update)
2433    }
2434}
2435
2436impl<V: View> ReadView for RenderContext<'_, V> {
2437    fn read_view<T: View>(&self, handle: &ViewHandle<T>) -> &T {
2438        self.app.read_view(handle)
2439    }
2440}
2441
2442impl<M> AsRef<AppContext> for ViewContext<'_, M> {
2443    fn as_ref(&self) -> &AppContext {
2444        &self.app.cx
2445    }
2446}
2447
2448impl<M> Deref for ViewContext<'_, M> {
2449    type Target = MutableAppContext;
2450
2451    fn deref(&self) -> &Self::Target {
2452        &self.app
2453    }
2454}
2455
2456impl<M> DerefMut for ViewContext<'_, M> {
2457    fn deref_mut(&mut self) -> &mut Self::Target {
2458        &mut self.app
2459    }
2460}
2461
2462impl<M> AsMut<MutableAppContext> for ViewContext<'_, M> {
2463    fn as_mut(&mut self) -> &mut MutableAppContext {
2464        self.app
2465    }
2466}
2467
2468impl<V> ReadModel for ViewContext<'_, V> {
2469    fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T {
2470        self.app.read_model(handle)
2471    }
2472}
2473
2474impl<V> UpgradeModelHandle for ViewContext<'_, V> {
2475    fn upgrade_model_handle<T: Entity>(
2476        &self,
2477        handle: WeakModelHandle<T>,
2478    ) -> Option<ModelHandle<T>> {
2479        self.cx.upgrade_model_handle(handle)
2480    }
2481}
2482
2483impl<V: View> UpdateModel for ViewContext<'_, V> {
2484    fn update_model<T: Entity, O>(
2485        &mut self,
2486        handle: &ModelHandle<T>,
2487        update: &mut dyn FnMut(&mut T, &mut ModelContext<T>) -> O,
2488    ) -> O {
2489        self.app.update_model(handle, update)
2490    }
2491}
2492
2493impl<V: View> ReadView for ViewContext<'_, V> {
2494    fn read_view<T: View>(&self, handle: &ViewHandle<T>) -> &T {
2495        self.app.read_view(handle)
2496    }
2497}
2498
2499impl<V: View> UpdateView for ViewContext<'_, V> {
2500    fn update_view<T, S>(
2501        &mut self,
2502        handle: &ViewHandle<T>,
2503        update: &mut dyn FnMut(&mut T, &mut ViewContext<T>) -> S,
2504    ) -> S
2505    where
2506        T: View,
2507    {
2508        self.app.update_view(handle, update)
2509    }
2510}
2511
2512pub trait Handle<T> {
2513    type Weak: 'static;
2514    fn id(&self) -> usize;
2515    fn location(&self) -> EntityLocation;
2516    fn downgrade(&self) -> Self::Weak;
2517    fn upgrade_from(weak: &Self::Weak, cx: &AppContext) -> Option<Self>
2518    where
2519        Self: Sized;
2520}
2521
2522#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash)]
2523pub enum EntityLocation {
2524    Model(usize),
2525    View(usize, usize),
2526}
2527
2528pub struct ModelHandle<T> {
2529    model_id: usize,
2530    model_type: PhantomData<T>,
2531    ref_counts: Arc<Mutex<RefCounts>>,
2532}
2533
2534impl<T: Entity> ModelHandle<T> {
2535    fn new(model_id: usize, ref_counts: &Arc<Mutex<RefCounts>>) -> Self {
2536        ref_counts.lock().inc_model(model_id);
2537        Self {
2538            model_id,
2539            model_type: PhantomData,
2540            ref_counts: ref_counts.clone(),
2541        }
2542    }
2543
2544    pub fn downgrade(&self) -> WeakModelHandle<T> {
2545        WeakModelHandle::new(self.model_id)
2546    }
2547
2548    pub fn id(&self) -> usize {
2549        self.model_id
2550    }
2551
2552    pub fn read<'a, C: ReadModel>(&self, cx: &'a C) -> &'a T {
2553        cx.read_model(self)
2554    }
2555
2556    pub fn read_with<'a, C, F, S>(&self, cx: &C, read: F) -> S
2557    where
2558        C: ReadModelWith,
2559        F: FnOnce(&T, &AppContext) -> S,
2560    {
2561        let mut read = Some(read);
2562        cx.read_model_with(self, &mut |model, cx| {
2563            let read = read.take().unwrap();
2564            read(model, cx)
2565        })
2566    }
2567
2568    pub fn update<C, F, S>(&self, cx: &mut C, update: F) -> S
2569    where
2570        C: UpdateModel,
2571        F: FnOnce(&mut T, &mut ModelContext<T>) -> S,
2572    {
2573        let mut update = Some(update);
2574        cx.update_model(self, &mut |model, cx| {
2575            let update = update.take().unwrap();
2576            update(model, cx)
2577        })
2578    }
2579
2580    pub fn next_notification(&self, cx: &TestAppContext) -> impl Future<Output = ()> {
2581        let (mut tx, mut rx) = mpsc::channel(1);
2582        let mut cx = cx.cx.borrow_mut();
2583        let subscription = cx.observe(self, move |_, _| {
2584            tx.blocking_send(()).ok();
2585        });
2586
2587        let duration = if std::env::var("CI").is_ok() {
2588            Duration::from_secs(5)
2589        } else {
2590            Duration::from_secs(1)
2591        };
2592
2593        async move {
2594            let notification = timeout(duration, rx.recv())
2595                .await
2596                .expect("next notification timed out");
2597            drop(subscription);
2598            notification.expect("model dropped while test was waiting for its next notification")
2599        }
2600    }
2601
2602    pub fn next_event(&self, cx: &TestAppContext) -> impl Future<Output = T::Event>
2603    where
2604        T::Event: Clone,
2605    {
2606        let (mut tx, mut rx) = mpsc::channel(1);
2607        let mut cx = cx.cx.borrow_mut();
2608        let subscription = cx.subscribe(self, move |_, event, _| {
2609            tx.blocking_send(event.clone()).ok();
2610        });
2611
2612        let duration = if std::env::var("CI").is_ok() {
2613            Duration::from_secs(5)
2614        } else {
2615            Duration::from_secs(1)
2616        };
2617
2618        async move {
2619            let event = timeout(duration, rx.recv())
2620                .await
2621                .expect("next event timed out");
2622            drop(subscription);
2623            event.expect("model dropped while test was waiting for its next event")
2624        }
2625    }
2626
2627    pub fn condition(
2628        &self,
2629        cx: &TestAppContext,
2630        mut predicate: impl FnMut(&T, &AppContext) -> bool,
2631    ) -> impl Future<Output = ()> {
2632        let (tx, mut rx) = mpsc::channel(1024);
2633
2634        let mut cx = cx.cx.borrow_mut();
2635        let subscriptions = (
2636            cx.observe(self, {
2637                let mut tx = tx.clone();
2638                move |_, _| {
2639                    tx.blocking_send(()).ok();
2640                }
2641            }),
2642            cx.subscribe(self, {
2643                let mut tx = tx.clone();
2644                move |_, _, _| {
2645                    tx.blocking_send(()).ok();
2646                }
2647            }),
2648        );
2649
2650        let cx = cx.weak_self.as_ref().unwrap().upgrade().unwrap();
2651        let handle = self.downgrade();
2652        let duration = if std::env::var("CI").is_ok() {
2653            Duration::from_secs(5)
2654        } else {
2655            Duration::from_secs(1)
2656        };
2657
2658        async move {
2659            timeout(duration, async move {
2660                loop {
2661                    {
2662                        let cx = cx.borrow();
2663                        let cx = cx.as_ref();
2664                        if predicate(
2665                            handle
2666                                .upgrade(cx)
2667                                .expect("model dropped with pending condition")
2668                                .read(cx),
2669                            cx,
2670                        ) {
2671                            break;
2672                        }
2673                    }
2674
2675                    rx.recv()
2676                        .await
2677                        .expect("model dropped with pending condition");
2678                }
2679            })
2680            .await
2681            .expect("condition timed out");
2682            drop(subscriptions);
2683        }
2684    }
2685}
2686
2687impl<T> Clone for ModelHandle<T> {
2688    fn clone(&self) -> Self {
2689        self.ref_counts.lock().inc_model(self.model_id);
2690        Self {
2691            model_id: self.model_id,
2692            model_type: PhantomData,
2693            ref_counts: self.ref_counts.clone(),
2694        }
2695    }
2696}
2697
2698impl<T> PartialEq for ModelHandle<T> {
2699    fn eq(&self, other: &Self) -> bool {
2700        self.model_id == other.model_id
2701    }
2702}
2703
2704impl<T> Eq for ModelHandle<T> {}
2705
2706impl<T> Hash for ModelHandle<T> {
2707    fn hash<H: Hasher>(&self, state: &mut H) {
2708        self.model_id.hash(state);
2709    }
2710}
2711
2712impl<T> std::borrow::Borrow<usize> for ModelHandle<T> {
2713    fn borrow(&self) -> &usize {
2714        &self.model_id
2715    }
2716}
2717
2718impl<T> Debug for ModelHandle<T> {
2719    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2720        f.debug_tuple(&format!("ModelHandle<{}>", type_name::<T>()))
2721            .field(&self.model_id)
2722            .finish()
2723    }
2724}
2725
2726unsafe impl<T> Send for ModelHandle<T> {}
2727unsafe impl<T> Sync for ModelHandle<T> {}
2728
2729impl<T> Drop for ModelHandle<T> {
2730    fn drop(&mut self) {
2731        self.ref_counts.lock().dec_model(self.model_id);
2732    }
2733}
2734
2735impl<T: Entity> Handle<T> for ModelHandle<T> {
2736    type Weak = WeakModelHandle<T>;
2737
2738    fn id(&self) -> usize {
2739        self.model_id
2740    }
2741
2742    fn location(&self) -> EntityLocation {
2743        EntityLocation::Model(self.model_id)
2744    }
2745
2746    fn downgrade(&self) -> Self::Weak {
2747        self.downgrade()
2748    }
2749
2750    fn upgrade_from(weak: &Self::Weak, cx: &AppContext) -> Option<Self>
2751    where
2752        Self: Sized,
2753    {
2754        weak.upgrade(cx)
2755    }
2756}
2757
2758pub struct WeakModelHandle<T> {
2759    model_id: usize,
2760    model_type: PhantomData<T>,
2761}
2762
2763unsafe impl<T> Send for WeakModelHandle<T> {}
2764unsafe impl<T> Sync for WeakModelHandle<T> {}
2765
2766impl<T: Entity> WeakModelHandle<T> {
2767    fn new(model_id: usize) -> Self {
2768        Self {
2769            model_id,
2770            model_type: PhantomData,
2771        }
2772    }
2773
2774    pub fn upgrade(self, cx: &impl UpgradeModelHandle) -> Option<ModelHandle<T>> {
2775        cx.upgrade_model_handle(self)
2776    }
2777}
2778
2779impl<T> Hash for WeakModelHandle<T> {
2780    fn hash<H: Hasher>(&self, state: &mut H) {
2781        self.model_id.hash(state)
2782    }
2783}
2784
2785impl<T> PartialEq for WeakModelHandle<T> {
2786    fn eq(&self, other: &Self) -> bool {
2787        self.model_id == other.model_id
2788    }
2789}
2790
2791impl<T> Eq for WeakModelHandle<T> {}
2792
2793impl<T> Clone for WeakModelHandle<T> {
2794    fn clone(&self) -> Self {
2795        Self {
2796            model_id: self.model_id,
2797            model_type: PhantomData,
2798        }
2799    }
2800}
2801
2802impl<T> Copy for WeakModelHandle<T> {}
2803
2804pub struct ViewHandle<T> {
2805    window_id: usize,
2806    view_id: usize,
2807    view_type: PhantomData<T>,
2808    ref_counts: Arc<Mutex<RefCounts>>,
2809}
2810
2811impl<T: View> ViewHandle<T> {
2812    fn new(window_id: usize, view_id: usize, ref_counts: &Arc<Mutex<RefCounts>>) -> Self {
2813        ref_counts.lock().inc_view(window_id, view_id);
2814        Self {
2815            window_id,
2816            view_id,
2817            view_type: PhantomData,
2818            ref_counts: ref_counts.clone(),
2819        }
2820    }
2821
2822    pub fn downgrade(&self) -> WeakViewHandle<T> {
2823        WeakViewHandle::new(self.window_id, self.view_id)
2824    }
2825
2826    pub fn window_id(&self) -> usize {
2827        self.window_id
2828    }
2829
2830    pub fn id(&self) -> usize {
2831        self.view_id
2832    }
2833
2834    pub fn read<'a, C: ReadView>(&self, cx: &'a C) -> &'a T {
2835        cx.read_view(self)
2836    }
2837
2838    pub fn read_with<C, F, S>(&self, cx: &C, read: F) -> S
2839    where
2840        C: ReadViewWith,
2841        F: FnOnce(&T, &AppContext) -> S,
2842    {
2843        let mut read = Some(read);
2844        cx.read_view_with(self, &mut |view, cx| {
2845            let read = read.take().unwrap();
2846            read(view, cx)
2847        })
2848    }
2849
2850    pub fn update<C, F, S>(&self, cx: &mut C, update: F) -> S
2851    where
2852        C: UpdateView,
2853        F: FnOnce(&mut T, &mut ViewContext<T>) -> S,
2854    {
2855        let mut update = Some(update);
2856        cx.update_view(self, &mut |view, cx| {
2857            let update = update.take().unwrap();
2858            update(view, cx)
2859        })
2860    }
2861
2862    pub fn is_focused(&self, cx: &AppContext) -> bool {
2863        cx.focused_view_id(self.window_id)
2864            .map_or(false, |focused_id| focused_id == self.view_id)
2865    }
2866
2867    pub fn condition(
2868        &self,
2869        cx: &TestAppContext,
2870        mut predicate: impl FnMut(&T, &AppContext) -> bool,
2871    ) -> impl Future<Output = ()> {
2872        let (tx, mut rx) = mpsc::channel(1024);
2873
2874        let mut cx = cx.cx.borrow_mut();
2875        let subscriptions = self.update(&mut *cx, |_, cx| {
2876            (
2877                cx.observe(self, {
2878                    let mut tx = tx.clone();
2879                    move |_, _, _| {
2880                        tx.blocking_send(()).ok();
2881                    }
2882                }),
2883                cx.subscribe(self, {
2884                    let mut tx = tx.clone();
2885                    move |_, _, _, _| {
2886                        tx.blocking_send(()).ok();
2887                    }
2888                }),
2889            )
2890        });
2891
2892        let cx = cx.weak_self.as_ref().unwrap().upgrade().unwrap();
2893        let handle = self.downgrade();
2894        let duration = if std::env::var("CI").is_ok() {
2895            Duration::from_secs(2)
2896        } else {
2897            Duration::from_millis(500)
2898        };
2899
2900        async move {
2901            timeout(duration, async move {
2902                loop {
2903                    {
2904                        let cx = cx.borrow();
2905                        let cx = cx.as_ref();
2906                        if predicate(
2907                            handle
2908                                .upgrade(cx)
2909                                .expect("view dropped with pending condition")
2910                                .read(cx),
2911                            cx,
2912                        ) {
2913                            break;
2914                        }
2915                    }
2916
2917                    rx.recv()
2918                        .await
2919                        .expect("view dropped with pending condition");
2920                }
2921            })
2922            .await
2923            .expect("condition timed out");
2924            drop(subscriptions);
2925        }
2926    }
2927}
2928
2929impl<T> Clone for ViewHandle<T> {
2930    fn clone(&self) -> Self {
2931        self.ref_counts
2932            .lock()
2933            .inc_view(self.window_id, self.view_id);
2934        Self {
2935            window_id: self.window_id,
2936            view_id: self.view_id,
2937            view_type: PhantomData,
2938            ref_counts: self.ref_counts.clone(),
2939        }
2940    }
2941}
2942
2943impl<T> PartialEq for ViewHandle<T> {
2944    fn eq(&self, other: &Self) -> bool {
2945        self.window_id == other.window_id && self.view_id == other.view_id
2946    }
2947}
2948
2949impl<T> Eq for ViewHandle<T> {}
2950
2951impl<T> Debug for ViewHandle<T> {
2952    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2953        f.debug_struct(&format!("ViewHandle<{}>", type_name::<T>()))
2954            .field("window_id", &self.window_id)
2955            .field("view_id", &self.view_id)
2956            .finish()
2957    }
2958}
2959
2960impl<T> Drop for ViewHandle<T> {
2961    fn drop(&mut self) {
2962        self.ref_counts
2963            .lock()
2964            .dec_view(self.window_id, self.view_id);
2965    }
2966}
2967
2968impl<T: View> Handle<T> for ViewHandle<T> {
2969    type Weak = WeakViewHandle<T>;
2970
2971    fn id(&self) -> usize {
2972        self.view_id
2973    }
2974
2975    fn location(&self) -> EntityLocation {
2976        EntityLocation::View(self.window_id, self.view_id)
2977    }
2978
2979    fn downgrade(&self) -> Self::Weak {
2980        self.downgrade()
2981    }
2982
2983    fn upgrade_from(weak: &Self::Weak, cx: &AppContext) -> Option<Self>
2984    where
2985        Self: Sized,
2986    {
2987        weak.upgrade(cx)
2988    }
2989}
2990
2991pub struct AnyViewHandle {
2992    window_id: usize,
2993    view_id: usize,
2994    view_type: TypeId,
2995    ref_counts: Arc<Mutex<RefCounts>>,
2996}
2997
2998impl AnyViewHandle {
2999    pub fn id(&self) -> usize {
3000        self.view_id
3001    }
3002
3003    pub fn is<T: 'static>(&self) -> bool {
3004        TypeId::of::<T>() == self.view_type
3005    }
3006
3007    pub fn is_focused(&self, cx: &AppContext) -> bool {
3008        cx.focused_view_id(self.window_id)
3009            .map_or(false, |focused_id| focused_id == self.view_id)
3010    }
3011
3012    pub fn downcast<T: View>(self) -> Option<ViewHandle<T>> {
3013        if self.is::<T>() {
3014            let result = Some(ViewHandle {
3015                window_id: self.window_id,
3016                view_id: self.view_id,
3017                ref_counts: self.ref_counts.clone(),
3018                view_type: PhantomData,
3019            });
3020            unsafe {
3021                Arc::decrement_strong_count(&self.ref_counts);
3022            }
3023            std::mem::forget(self);
3024            result
3025        } else {
3026            None
3027        }
3028    }
3029}
3030
3031impl Clone for AnyViewHandle {
3032    fn clone(&self) -> Self {
3033        self.ref_counts
3034            .lock()
3035            .inc_view(self.window_id, self.view_id);
3036        Self {
3037            window_id: self.window_id,
3038            view_id: self.view_id,
3039            view_type: self.view_type,
3040            ref_counts: self.ref_counts.clone(),
3041        }
3042    }
3043}
3044
3045impl From<&AnyViewHandle> for AnyViewHandle {
3046    fn from(handle: &AnyViewHandle) -> Self {
3047        handle.clone()
3048    }
3049}
3050
3051impl<T: View> From<&ViewHandle<T>> for AnyViewHandle {
3052    fn from(handle: &ViewHandle<T>) -> Self {
3053        handle
3054            .ref_counts
3055            .lock()
3056            .inc_view(handle.window_id, handle.view_id);
3057        AnyViewHandle {
3058            window_id: handle.window_id,
3059            view_id: handle.view_id,
3060            view_type: TypeId::of::<T>(),
3061            ref_counts: handle.ref_counts.clone(),
3062        }
3063    }
3064}
3065
3066impl<T: View> From<ViewHandle<T>> for AnyViewHandle {
3067    fn from(handle: ViewHandle<T>) -> Self {
3068        let any_handle = AnyViewHandle {
3069            window_id: handle.window_id,
3070            view_id: handle.view_id,
3071            view_type: TypeId::of::<T>(),
3072            ref_counts: handle.ref_counts.clone(),
3073        };
3074        unsafe {
3075            Arc::decrement_strong_count(&handle.ref_counts);
3076        }
3077        std::mem::forget(handle);
3078        any_handle
3079    }
3080}
3081
3082impl Drop for AnyViewHandle {
3083    fn drop(&mut self) {
3084        self.ref_counts
3085            .lock()
3086            .dec_view(self.window_id, self.view_id);
3087    }
3088}
3089
3090pub struct AnyModelHandle {
3091    model_id: usize,
3092    ref_counts: Arc<Mutex<RefCounts>>,
3093}
3094
3095impl<T: Entity> From<ModelHandle<T>> for AnyModelHandle {
3096    fn from(handle: ModelHandle<T>) -> Self {
3097        handle.ref_counts.lock().inc_model(handle.model_id);
3098        Self {
3099            model_id: handle.model_id,
3100            ref_counts: handle.ref_counts.clone(),
3101        }
3102    }
3103}
3104
3105impl Drop for AnyModelHandle {
3106    fn drop(&mut self) {
3107        self.ref_counts.lock().dec_model(self.model_id);
3108    }
3109}
3110pub struct WeakViewHandle<T> {
3111    window_id: usize,
3112    view_id: usize,
3113    view_type: PhantomData<T>,
3114}
3115
3116impl<T: View> WeakViewHandle<T> {
3117    fn new(window_id: usize, view_id: usize) -> Self {
3118        Self {
3119            window_id,
3120            view_id,
3121            view_type: PhantomData,
3122        }
3123    }
3124
3125    pub fn id(&self) -> usize {
3126        self.view_id
3127    }
3128
3129    pub fn upgrade(&self, cx: &AppContext) -> Option<ViewHandle<T>> {
3130        if cx.ref_counts.lock().is_entity_alive(self.view_id) {
3131            Some(ViewHandle::new(
3132                self.window_id,
3133                self.view_id,
3134                &cx.ref_counts,
3135            ))
3136        } else {
3137            None
3138        }
3139    }
3140}
3141
3142impl<T> Clone for WeakViewHandle<T> {
3143    fn clone(&self) -> Self {
3144        Self {
3145            window_id: self.window_id,
3146            view_id: self.view_id,
3147            view_type: PhantomData,
3148        }
3149    }
3150}
3151
3152#[derive(Clone, Copy, PartialEq, Eq, Hash)]
3153pub struct ElementStateId(usize, usize);
3154
3155impl From<usize> for ElementStateId {
3156    fn from(id: usize) -> Self {
3157        Self(id, 0)
3158    }
3159}
3160
3161impl From<(usize, usize)> for ElementStateId {
3162    fn from(id: (usize, usize)) -> Self {
3163        Self(id.0, id.1)
3164    }
3165}
3166
3167pub struct ElementStateHandle<T> {
3168    value_type: PhantomData<T>,
3169    tag_type_id: TypeId,
3170    id: ElementStateId,
3171    ref_counts: Weak<Mutex<RefCounts>>,
3172}
3173
3174impl<T: 'static> ElementStateHandle<T> {
3175    fn new(tag_type_id: TypeId, id: ElementStateId, ref_counts: &Arc<Mutex<RefCounts>>) -> Self {
3176        ref_counts.lock().inc_element_state(tag_type_id, id);
3177        Self {
3178            value_type: PhantomData,
3179            tag_type_id,
3180            id,
3181            ref_counts: Arc::downgrade(ref_counts),
3182        }
3183    }
3184
3185    pub fn read<'a>(&self, cx: &'a AppContext) -> &'a T {
3186        cx.element_states
3187            .get(&(self.tag_type_id, self.id))
3188            .unwrap()
3189            .downcast_ref()
3190            .unwrap()
3191    }
3192
3193    pub fn update<C, R>(&self, cx: &mut C, f: impl FnOnce(&mut T, &mut C) -> R) -> R
3194    where
3195        C: DerefMut<Target = MutableAppContext>,
3196    {
3197        let mut element_state = cx
3198            .deref_mut()
3199            .cx
3200            .element_states
3201            .remove(&(self.tag_type_id, self.id))
3202            .unwrap();
3203        let result = f(element_state.downcast_mut().unwrap(), cx);
3204        cx.deref_mut()
3205            .cx
3206            .element_states
3207            .insert((self.tag_type_id, self.id), element_state);
3208        result
3209    }
3210}
3211
3212impl<T> Drop for ElementStateHandle<T> {
3213    fn drop(&mut self) {
3214        if let Some(ref_counts) = self.ref_counts.upgrade() {
3215            ref_counts
3216                .lock()
3217                .dec_element_state(self.tag_type_id, self.id);
3218        }
3219    }
3220}
3221
3222pub struct CursorStyleHandle {
3223    id: usize,
3224    next_cursor_style_handle_id: Arc<AtomicUsize>,
3225    platform: Arc<dyn Platform>,
3226}
3227
3228impl Drop for CursorStyleHandle {
3229    fn drop(&mut self) {
3230        if self.id + 1 == self.next_cursor_style_handle_id.load(SeqCst) {
3231            self.platform.set_cursor_style(CursorStyle::Arrow);
3232        }
3233    }
3234}
3235
3236#[must_use]
3237pub enum Subscription {
3238    Subscription {
3239        id: usize,
3240        entity_id: usize,
3241        subscriptions: Option<Weak<Mutex<HashMap<usize, BTreeMap<usize, SubscriptionCallback>>>>>,
3242    },
3243    Observation {
3244        id: usize,
3245        entity_id: usize,
3246        observations: Option<Weak<Mutex<HashMap<usize, BTreeMap<usize, ObservationCallback>>>>>,
3247    },
3248}
3249
3250impl Subscription {
3251    pub fn detach(&mut self) {
3252        match self {
3253            Subscription::Subscription { subscriptions, .. } => {
3254                subscriptions.take();
3255            }
3256            Subscription::Observation { observations, .. } => {
3257                observations.take();
3258            }
3259        }
3260    }
3261}
3262
3263impl Drop for Subscription {
3264    fn drop(&mut self) {
3265        match self {
3266            Subscription::Observation {
3267                id,
3268                entity_id,
3269                observations,
3270            } => {
3271                if let Some(observations) = observations.as_ref().and_then(Weak::upgrade) {
3272                    if let Some(observations) = observations.lock().get_mut(entity_id) {
3273                        observations.remove(id);
3274                    }
3275                }
3276            }
3277            Subscription::Subscription {
3278                id,
3279                entity_id,
3280                subscriptions,
3281            } => {
3282                if let Some(subscriptions) = subscriptions.as_ref().and_then(Weak::upgrade) {
3283                    if let Some(subscriptions) = subscriptions.lock().get_mut(entity_id) {
3284                        subscriptions.remove(id);
3285                    }
3286                }
3287            }
3288        }
3289    }
3290}
3291
3292#[derive(Default)]
3293struct RefCounts {
3294    entity_counts: HashMap<usize, usize>,
3295    element_state_counts: HashMap<(TypeId, ElementStateId), usize>,
3296    dropped_models: HashSet<usize>,
3297    dropped_views: HashSet<(usize, usize)>,
3298    dropped_element_states: HashSet<(TypeId, ElementStateId)>,
3299}
3300
3301impl RefCounts {
3302    fn inc_model(&mut self, model_id: usize) {
3303        match self.entity_counts.entry(model_id) {
3304            Entry::Occupied(mut entry) => {
3305                *entry.get_mut() += 1;
3306            }
3307            Entry::Vacant(entry) => {
3308                entry.insert(1);
3309                self.dropped_models.remove(&model_id);
3310            }
3311        }
3312    }
3313
3314    fn inc_view(&mut self, window_id: usize, view_id: usize) {
3315        match self.entity_counts.entry(view_id) {
3316            Entry::Occupied(mut entry) => *entry.get_mut() += 1,
3317            Entry::Vacant(entry) => {
3318                entry.insert(1);
3319                self.dropped_views.remove(&(window_id, view_id));
3320            }
3321        }
3322    }
3323
3324    fn inc_element_state(&mut self, tag_type_id: TypeId, id: ElementStateId) {
3325        match self.element_state_counts.entry((tag_type_id, id)) {
3326            Entry::Occupied(mut entry) => *entry.get_mut() += 1,
3327            Entry::Vacant(entry) => {
3328                entry.insert(1);
3329                self.dropped_element_states.remove(&(tag_type_id, id));
3330            }
3331        }
3332    }
3333
3334    fn dec_model(&mut self, model_id: usize) {
3335        let count = self.entity_counts.get_mut(&model_id).unwrap();
3336        *count -= 1;
3337        if *count == 0 {
3338            self.entity_counts.remove(&model_id);
3339            self.dropped_models.insert(model_id);
3340        }
3341    }
3342
3343    fn dec_view(&mut self, window_id: usize, view_id: usize) {
3344        let count = self.entity_counts.get_mut(&view_id).unwrap();
3345        *count -= 1;
3346        if *count == 0 {
3347            self.entity_counts.remove(&view_id);
3348            self.dropped_views.insert((window_id, view_id));
3349        }
3350    }
3351
3352    fn dec_element_state(&mut self, tag_type_id: TypeId, id: ElementStateId) {
3353        let key = (tag_type_id, id);
3354        let count = self.element_state_counts.get_mut(&key).unwrap();
3355        *count -= 1;
3356        if *count == 0 {
3357            self.element_state_counts.remove(&key);
3358            self.dropped_element_states.insert(key);
3359        }
3360    }
3361
3362    fn is_entity_alive(&self, entity_id: usize) -> bool {
3363        self.entity_counts.contains_key(&entity_id)
3364    }
3365
3366    fn take_dropped(
3367        &mut self,
3368    ) -> (
3369        HashSet<usize>,
3370        HashSet<(usize, usize)>,
3371        HashSet<(TypeId, ElementStateId)>,
3372    ) {
3373        (
3374            std::mem::take(&mut self.dropped_models),
3375            std::mem::take(&mut self.dropped_views),
3376            std::mem::take(&mut self.dropped_element_states),
3377        )
3378    }
3379}
3380
3381#[cfg(test)]
3382mod tests {
3383    use super::*;
3384    use crate::elements::*;
3385    use smol::future::poll_once;
3386    use std::sync::atomic::{AtomicUsize, Ordering::SeqCst};
3387
3388    #[crate::test(self)]
3389    fn test_model_handles(cx: &mut MutableAppContext) {
3390        struct Model {
3391            other: Option<ModelHandle<Model>>,
3392            events: Vec<String>,
3393        }
3394
3395        impl Entity for Model {
3396            type Event = usize;
3397        }
3398
3399        impl Model {
3400            fn new(other: Option<ModelHandle<Self>>, cx: &mut ModelContext<Self>) -> Self {
3401                if let Some(other) = other.as_ref() {
3402                    cx.observe(other, |me, _, _| {
3403                        me.events.push("notified".into());
3404                    })
3405                    .detach();
3406                    cx.subscribe(other, |me, _, event, _| {
3407                        me.events.push(format!("observed event {}", event));
3408                    })
3409                    .detach();
3410                }
3411
3412                Self {
3413                    other,
3414                    events: Vec::new(),
3415                }
3416            }
3417        }
3418
3419        let handle_1 = cx.add_model(|cx| Model::new(None, cx));
3420        let handle_2 = cx.add_model(|cx| Model::new(Some(handle_1.clone()), cx));
3421        assert_eq!(cx.cx.models.len(), 2);
3422
3423        handle_1.update(cx, |model, cx| {
3424            model.events.push("updated".into());
3425            cx.emit(1);
3426            cx.notify();
3427            cx.emit(2);
3428        });
3429        assert_eq!(handle_1.read(cx).events, vec!["updated".to_string()]);
3430        assert_eq!(
3431            handle_2.read(cx).events,
3432            vec![
3433                "observed event 1".to_string(),
3434                "notified".to_string(),
3435                "observed event 2".to_string(),
3436            ]
3437        );
3438
3439        handle_2.update(cx, |model, _| {
3440            drop(handle_1);
3441            model.other.take();
3442        });
3443
3444        assert_eq!(cx.cx.models.len(), 1);
3445        assert!(cx.subscriptions.lock().is_empty());
3446        assert!(cx.observations.lock().is_empty());
3447    }
3448
3449    #[crate::test(self)]
3450    fn test_subscribe_and_emit_from_model(cx: &mut MutableAppContext) {
3451        #[derive(Default)]
3452        struct Model {
3453            events: Vec<usize>,
3454        }
3455
3456        impl Entity for Model {
3457            type Event = usize;
3458        }
3459
3460        let handle_1 = cx.add_model(|_| Model::default());
3461        let handle_2 = cx.add_model(|_| Model::default());
3462        let handle_2b = handle_2.clone();
3463
3464        handle_1.update(cx, |_, c| {
3465            c.subscribe(&handle_2, move |model: &mut Model, _, event, c| {
3466                model.events.push(*event);
3467
3468                c.subscribe(&handle_2b, |model, _, event, _| {
3469                    model.events.push(*event * 2);
3470                })
3471                .detach();
3472            })
3473            .detach();
3474        });
3475
3476        handle_2.update(cx, |_, c| c.emit(7));
3477        assert_eq!(handle_1.read(cx).events, vec![7]);
3478
3479        handle_2.update(cx, |_, c| c.emit(5));
3480        assert_eq!(handle_1.read(cx).events, vec![7, 5, 10]);
3481    }
3482
3483    #[crate::test(self)]
3484    fn test_observe_and_notify_from_model(cx: &mut MutableAppContext) {
3485        #[derive(Default)]
3486        struct Model {
3487            count: usize,
3488            events: Vec<usize>,
3489        }
3490
3491        impl Entity for Model {
3492            type Event = ();
3493        }
3494
3495        let handle_1 = cx.add_model(|_| Model::default());
3496        let handle_2 = cx.add_model(|_| Model::default());
3497        let handle_2b = handle_2.clone();
3498
3499        handle_1.update(cx, |_, c| {
3500            c.observe(&handle_2, move |model, observed, c| {
3501                model.events.push(observed.read(c).count);
3502                c.observe(&handle_2b, |model, observed, c| {
3503                    model.events.push(observed.read(c).count * 2);
3504                })
3505                .detach();
3506            })
3507            .detach();
3508        });
3509
3510        handle_2.update(cx, |model, c| {
3511            model.count = 7;
3512            c.notify()
3513        });
3514        assert_eq!(handle_1.read(cx).events, vec![7]);
3515
3516        handle_2.update(cx, |model, c| {
3517            model.count = 5;
3518            c.notify()
3519        });
3520        assert_eq!(handle_1.read(cx).events, vec![7, 5, 10])
3521    }
3522
3523    #[crate::test(self)]
3524    fn test_view_handles(cx: &mut MutableAppContext) {
3525        struct View {
3526            other: Option<ViewHandle<View>>,
3527            events: Vec<String>,
3528        }
3529
3530        impl Entity for View {
3531            type Event = usize;
3532        }
3533
3534        impl super::View for View {
3535            fn render(&mut self, _: &mut RenderContext<Self>) -> ElementBox {
3536                Empty::new().boxed()
3537            }
3538
3539            fn ui_name() -> &'static str {
3540                "View"
3541            }
3542        }
3543
3544        impl View {
3545            fn new(other: Option<ViewHandle<View>>, cx: &mut ViewContext<Self>) -> Self {
3546                if let Some(other) = other.as_ref() {
3547                    cx.subscribe(other, |me, _, event, _| {
3548                        me.events.push(format!("observed event {}", event));
3549                    })
3550                    .detach();
3551                }
3552                Self {
3553                    other,
3554                    events: Vec::new(),
3555                }
3556            }
3557        }
3558
3559        let (window_id, _) = cx.add_window(Default::default(), |cx| View::new(None, cx));
3560        let handle_1 = cx.add_view(window_id, |cx| View::new(None, cx));
3561        let handle_2 = cx.add_view(window_id, |cx| View::new(Some(handle_1.clone()), cx));
3562        assert_eq!(cx.cx.views.len(), 3);
3563
3564        handle_1.update(cx, |view, cx| {
3565            view.events.push("updated".into());
3566            cx.emit(1);
3567            cx.emit(2);
3568        });
3569        assert_eq!(handle_1.read(cx).events, vec!["updated".to_string()]);
3570        assert_eq!(
3571            handle_2.read(cx).events,
3572            vec![
3573                "observed event 1".to_string(),
3574                "observed event 2".to_string(),
3575            ]
3576        );
3577
3578        handle_2.update(cx, |view, _| {
3579            drop(handle_1);
3580            view.other.take();
3581        });
3582
3583        assert_eq!(cx.cx.views.len(), 2);
3584        assert!(cx.subscriptions.lock().is_empty());
3585        assert!(cx.observations.lock().is_empty());
3586    }
3587
3588    #[crate::test(self)]
3589    fn test_add_window(cx: &mut MutableAppContext) {
3590        struct View {
3591            mouse_down_count: Arc<AtomicUsize>,
3592        }
3593
3594        impl Entity for View {
3595            type Event = ();
3596        }
3597
3598        impl super::View for View {
3599            fn render(&mut self, _: &mut RenderContext<Self>) -> ElementBox {
3600                let mouse_down_count = self.mouse_down_count.clone();
3601                EventHandler::new(Empty::new().boxed())
3602                    .on_mouse_down(move |_| {
3603                        mouse_down_count.fetch_add(1, SeqCst);
3604                        true
3605                    })
3606                    .boxed()
3607            }
3608
3609            fn ui_name() -> &'static str {
3610                "View"
3611            }
3612        }
3613
3614        let mouse_down_count = Arc::new(AtomicUsize::new(0));
3615        let (window_id, _) = cx.add_window(Default::default(), |_| View {
3616            mouse_down_count: mouse_down_count.clone(),
3617        });
3618        let presenter = cx.presenters_and_platform_windows[&window_id].0.clone();
3619        // Ensure window's root element is in a valid lifecycle state.
3620        presenter.borrow_mut().dispatch_event(
3621            Event::LeftMouseDown {
3622                position: Default::default(),
3623                ctrl: false,
3624                alt: false,
3625                shift: false,
3626                cmd: false,
3627                click_count: 1,
3628            },
3629            cx,
3630        );
3631        assert_eq!(mouse_down_count.load(SeqCst), 1);
3632    }
3633
3634    #[crate::test(self)]
3635    fn test_entity_release_hooks(cx: &mut MutableAppContext) {
3636        struct Model {
3637            released: Arc<Mutex<bool>>,
3638        }
3639
3640        struct View {
3641            released: Arc<Mutex<bool>>,
3642        }
3643
3644        impl Entity for Model {
3645            type Event = ();
3646
3647            fn release(&mut self, _: &mut MutableAppContext) {
3648                *self.released.lock() = true;
3649            }
3650        }
3651
3652        impl Entity for View {
3653            type Event = ();
3654
3655            fn release(&mut self, _: &mut MutableAppContext) {
3656                *self.released.lock() = true;
3657            }
3658        }
3659
3660        impl super::View for View {
3661            fn ui_name() -> &'static str {
3662                "View"
3663            }
3664
3665            fn render(&mut self, _: &mut RenderContext<Self>) -> ElementBox {
3666                Empty::new().boxed()
3667            }
3668        }
3669
3670        let model_released = Arc::new(Mutex::new(false));
3671        let view_released = Arc::new(Mutex::new(false));
3672
3673        let model = cx.add_model(|_| Model {
3674            released: model_released.clone(),
3675        });
3676
3677        let (window_id, _) = cx.add_window(Default::default(), |_| View {
3678            released: view_released.clone(),
3679        });
3680
3681        assert!(!*model_released.lock());
3682        assert!(!*view_released.lock());
3683
3684        cx.update(move |_| {
3685            drop(model);
3686        });
3687        assert!(*model_released.lock());
3688
3689        drop(cx.remove_window(window_id));
3690        assert!(*view_released.lock());
3691    }
3692
3693    #[crate::test(self)]
3694    fn test_subscribe_and_emit_from_view(cx: &mut MutableAppContext) {
3695        #[derive(Default)]
3696        struct View {
3697            events: Vec<usize>,
3698        }
3699
3700        impl Entity for View {
3701            type Event = usize;
3702        }
3703
3704        impl super::View for View {
3705            fn render(&mut self, _: &mut RenderContext<Self>) -> ElementBox {
3706                Empty::new().boxed()
3707            }
3708
3709            fn ui_name() -> &'static str {
3710                "View"
3711            }
3712        }
3713
3714        struct Model;
3715
3716        impl Entity for Model {
3717            type Event = usize;
3718        }
3719
3720        let (window_id, handle_1) = cx.add_window(Default::default(), |_| View::default());
3721        let handle_2 = cx.add_view(window_id, |_| View::default());
3722        let handle_2b = handle_2.clone();
3723        let handle_3 = cx.add_model(|_| Model);
3724
3725        handle_1.update(cx, |_, c| {
3726            c.subscribe(&handle_2, move |me, _, event, c| {
3727                me.events.push(*event);
3728
3729                c.subscribe(&handle_2b, |me, _, event, _| {
3730                    me.events.push(*event * 2);
3731                })
3732                .detach();
3733            })
3734            .detach();
3735
3736            c.subscribe(&handle_3, |me, _, event, _| {
3737                me.events.push(*event);
3738            })
3739            .detach();
3740        });
3741
3742        handle_2.update(cx, |_, c| c.emit(7));
3743        assert_eq!(handle_1.read(cx).events, vec![7]);
3744
3745        handle_2.update(cx, |_, c| c.emit(5));
3746        assert_eq!(handle_1.read(cx).events, vec![7, 5, 10]);
3747
3748        handle_3.update(cx, |_, c| c.emit(9));
3749        assert_eq!(handle_1.read(cx).events, vec![7, 5, 10, 9]);
3750    }
3751
3752    #[crate::test(self)]
3753    fn test_dropping_subscribers(cx: &mut MutableAppContext) {
3754        struct View;
3755
3756        impl Entity for View {
3757            type Event = ();
3758        }
3759
3760        impl super::View for View {
3761            fn render(&mut self, _: &mut RenderContext<Self>) -> ElementBox {
3762                Empty::new().boxed()
3763            }
3764
3765            fn ui_name() -> &'static str {
3766                "View"
3767            }
3768        }
3769
3770        struct Model;
3771
3772        impl Entity for Model {
3773            type Event = ();
3774        }
3775
3776        let (window_id, _) = cx.add_window(Default::default(), |_| View);
3777        let observing_view = cx.add_view(window_id, |_| View);
3778        let emitting_view = cx.add_view(window_id, |_| View);
3779        let observing_model = cx.add_model(|_| Model);
3780        let observed_model = cx.add_model(|_| Model);
3781
3782        observing_view.update(cx, |_, cx| {
3783            cx.subscribe(&emitting_view, |_, _, _, _| {}).detach();
3784            cx.subscribe(&observed_model, |_, _, _, _| {}).detach();
3785        });
3786        observing_model.update(cx, |_, cx| {
3787            cx.subscribe(&observed_model, |_, _, _, _| {}).detach();
3788        });
3789
3790        cx.update(|_| {
3791            drop(observing_view);
3792            drop(observing_model);
3793        });
3794
3795        emitting_view.update(cx, |_, cx| cx.emit(()));
3796        observed_model.update(cx, |_, cx| cx.emit(()));
3797    }
3798
3799    #[crate::test(self)]
3800    fn test_observe_and_notify_from_view(cx: &mut MutableAppContext) {
3801        #[derive(Default)]
3802        struct View {
3803            events: Vec<usize>,
3804        }
3805
3806        impl Entity for View {
3807            type Event = usize;
3808        }
3809
3810        impl super::View for View {
3811            fn render(&mut self, _: &mut RenderContext<Self>) -> ElementBox {
3812                Empty::new().boxed()
3813            }
3814
3815            fn ui_name() -> &'static str {
3816                "View"
3817            }
3818        }
3819
3820        #[derive(Default)]
3821        struct Model {
3822            count: usize,
3823        }
3824
3825        impl Entity for Model {
3826            type Event = ();
3827        }
3828
3829        let (_, view) = cx.add_window(Default::default(), |_| View::default());
3830        let model = cx.add_model(|_| Model::default());
3831
3832        view.update(cx, |_, c| {
3833            c.observe(&model, |me, observed, c| {
3834                me.events.push(observed.read(c).count)
3835            })
3836            .detach();
3837        });
3838
3839        model.update(cx, |model, c| {
3840            model.count = 11;
3841            c.notify();
3842        });
3843        assert_eq!(view.read(cx).events, vec![11]);
3844    }
3845
3846    #[crate::test(self)]
3847    fn test_dropping_observers(cx: &mut MutableAppContext) {
3848        struct View;
3849
3850        impl Entity for View {
3851            type Event = ();
3852        }
3853
3854        impl super::View for View {
3855            fn render(&mut self, _: &mut RenderContext<Self>) -> ElementBox {
3856                Empty::new().boxed()
3857            }
3858
3859            fn ui_name() -> &'static str {
3860                "View"
3861            }
3862        }
3863
3864        struct Model;
3865
3866        impl Entity for Model {
3867            type Event = ();
3868        }
3869
3870        let (window_id, _) = cx.add_window(Default::default(), |_| View);
3871        let observing_view = cx.add_view(window_id, |_| View);
3872        let observing_model = cx.add_model(|_| Model);
3873        let observed_model = cx.add_model(|_| Model);
3874
3875        observing_view.update(cx, |_, cx| {
3876            cx.observe(&observed_model, |_, _, _| {}).detach();
3877        });
3878        observing_model.update(cx, |_, cx| {
3879            cx.observe(&observed_model, |_, _, _| {}).detach();
3880        });
3881
3882        cx.update(|_| {
3883            drop(observing_view);
3884            drop(observing_model);
3885        });
3886
3887        observed_model.update(cx, |_, cx| cx.notify());
3888    }
3889
3890    #[crate::test(self)]
3891    fn test_focus(cx: &mut MutableAppContext) {
3892        struct View {
3893            name: String,
3894            events: Arc<Mutex<Vec<String>>>,
3895        }
3896
3897        impl Entity for View {
3898            type Event = ();
3899        }
3900
3901        impl super::View for View {
3902            fn render(&mut self, _: &mut RenderContext<Self>) -> ElementBox {
3903                Empty::new().boxed()
3904            }
3905
3906            fn ui_name() -> &'static str {
3907                "View"
3908            }
3909
3910            fn on_focus(&mut self, _: &mut ViewContext<Self>) {
3911                self.events.lock().push(format!("{} focused", &self.name));
3912            }
3913
3914            fn on_blur(&mut self, _: &mut ViewContext<Self>) {
3915                self.events.lock().push(format!("{} blurred", &self.name));
3916            }
3917        }
3918
3919        let events: Arc<Mutex<Vec<String>>> = Default::default();
3920        let (window_id, view_1) = cx.add_window(Default::default(), |_| View {
3921            events: events.clone(),
3922            name: "view 1".to_string(),
3923        });
3924        let view_2 = cx.add_view(window_id, |_| View {
3925            events: events.clone(),
3926            name: "view 2".to_string(),
3927        });
3928
3929        view_1.update(cx, |_, cx| cx.focus(&view_2));
3930        view_1.update(cx, |_, cx| cx.focus(&view_1));
3931        view_1.update(cx, |_, cx| cx.focus(&view_2));
3932        view_1.update(cx, |_, _| drop(view_2));
3933
3934        assert_eq!(
3935            *events.lock(),
3936            [
3937                "view 1 focused".to_string(),
3938                "view 1 blurred".to_string(),
3939                "view 2 focused".to_string(),
3940                "view 2 blurred".to_string(),
3941                "view 1 focused".to_string(),
3942                "view 1 blurred".to_string(),
3943                "view 2 focused".to_string(),
3944                "view 1 focused".to_string(),
3945            ],
3946        );
3947    }
3948
3949    #[crate::test(self)]
3950    fn test_dispatch_action(cx: &mut MutableAppContext) {
3951        struct ViewA {
3952            id: usize,
3953        }
3954
3955        impl Entity for ViewA {
3956            type Event = ();
3957        }
3958
3959        impl View for ViewA {
3960            fn render(&mut self, _: &mut RenderContext<Self>) -> ElementBox {
3961                Empty::new().boxed()
3962            }
3963
3964            fn ui_name() -> &'static str {
3965                "View"
3966            }
3967        }
3968
3969        struct ViewB {
3970            id: usize,
3971        }
3972
3973        impl Entity for ViewB {
3974            type Event = ();
3975        }
3976
3977        impl View for ViewB {
3978            fn render(&mut self, _: &mut RenderContext<Self>) -> ElementBox {
3979                Empty::new().boxed()
3980            }
3981
3982            fn ui_name() -> &'static str {
3983                "View"
3984            }
3985        }
3986
3987        action!(Action, &'static str);
3988
3989        let actions = Rc::new(RefCell::new(Vec::new()));
3990
3991        let actions_clone = actions.clone();
3992        cx.add_global_action(move |_: &Action, _: &mut MutableAppContext| {
3993            actions_clone.borrow_mut().push("global".to_string());
3994        });
3995
3996        let actions_clone = actions.clone();
3997        cx.add_action(move |view: &mut ViewA, action: &Action, cx| {
3998            assert_eq!(action.0, "bar");
3999            cx.propagate_action();
4000            actions_clone.borrow_mut().push(format!("{} a", view.id));
4001        });
4002
4003        let actions_clone = actions.clone();
4004        cx.add_action(move |view: &mut ViewA, _: &Action, cx| {
4005            if view.id != 1 {
4006                cx.propagate_action();
4007            }
4008            actions_clone.borrow_mut().push(format!("{} b", view.id));
4009        });
4010
4011        let actions_clone = actions.clone();
4012        cx.add_action(move |view: &mut ViewB, _: &Action, cx| {
4013            cx.propagate_action();
4014            actions_clone.borrow_mut().push(format!("{} c", view.id));
4015        });
4016
4017        let actions_clone = actions.clone();
4018        cx.add_action(move |view: &mut ViewB, _: &Action, cx| {
4019            cx.propagate_action();
4020            actions_clone.borrow_mut().push(format!("{} d", view.id));
4021        });
4022
4023        let (window_id, view_1) = cx.add_window(Default::default(), |_| ViewA { id: 1 });
4024        let view_2 = cx.add_view(window_id, |_| ViewB { id: 2 });
4025        let view_3 = cx.add_view(window_id, |_| ViewA { id: 3 });
4026        let view_4 = cx.add_view(window_id, |_| ViewB { id: 4 });
4027
4028        cx.dispatch_action(
4029            window_id,
4030            vec![view_1.id(), view_2.id(), view_3.id(), view_4.id()],
4031            &Action("bar"),
4032        );
4033
4034        assert_eq!(
4035            *actions.borrow(),
4036            vec!["4 d", "4 c", "3 b", "3 a", "2 d", "2 c", "1 b"]
4037        );
4038
4039        // Remove view_1, which doesn't propagate the action
4040        actions.borrow_mut().clear();
4041        cx.dispatch_action(
4042            window_id,
4043            vec![view_2.id(), view_3.id(), view_4.id()],
4044            &Action("bar"),
4045        );
4046
4047        assert_eq!(
4048            *actions.borrow(),
4049            vec!["4 d", "4 c", "3 b", "3 a", "2 d", "2 c", "global"]
4050        );
4051    }
4052
4053    #[crate::test(self)]
4054    fn test_dispatch_keystroke(cx: &mut MutableAppContext) {
4055        use std::cell::Cell;
4056
4057        action!(Action, &'static str);
4058
4059        struct View {
4060            id: usize,
4061            keymap_context: keymap::Context,
4062        }
4063
4064        impl Entity for View {
4065            type Event = ();
4066        }
4067
4068        impl super::View for View {
4069            fn render(&mut self, _: &mut RenderContext<Self>) -> ElementBox {
4070                Empty::new().boxed()
4071            }
4072
4073            fn ui_name() -> &'static str {
4074                "View"
4075            }
4076
4077            fn keymap_context(&self, _: &AppContext) -> keymap::Context {
4078                self.keymap_context.clone()
4079            }
4080        }
4081
4082        impl View {
4083            fn new(id: usize) -> Self {
4084                View {
4085                    id,
4086                    keymap_context: keymap::Context::default(),
4087                }
4088            }
4089        }
4090
4091        let mut view_1 = View::new(1);
4092        let mut view_2 = View::new(2);
4093        let mut view_3 = View::new(3);
4094        view_1.keymap_context.set.insert("a".into());
4095        view_2.keymap_context.set.insert("a".into());
4096        view_2.keymap_context.set.insert("b".into());
4097        view_3.keymap_context.set.insert("a".into());
4098        view_3.keymap_context.set.insert("b".into());
4099        view_3.keymap_context.set.insert("c".into());
4100
4101        let (window_id, view_1) = cx.add_window(Default::default(), |_| view_1);
4102        let view_2 = cx.add_view(window_id, |_| view_2);
4103        let view_3 = cx.add_view(window_id, |_| view_3);
4104
4105        // This keymap's only binding dispatches an action on view 2 because that view will have
4106        // "a" and "b" in its context, but not "c".
4107        cx.add_bindings(vec![keymap::Binding::new(
4108            "a",
4109            Action("a"),
4110            Some("a && b && !c"),
4111        )]);
4112
4113        let handled_action = Rc::new(Cell::new(false));
4114        let handled_action_clone = handled_action.clone();
4115        cx.add_action(move |view: &mut View, action: &Action, _| {
4116            handled_action_clone.set(true);
4117            assert_eq!(view.id, 2);
4118            assert_eq!(action.0, "a");
4119        });
4120
4121        cx.dispatch_keystroke(
4122            window_id,
4123            vec![view_1.id(), view_2.id(), view_3.id()],
4124            &Keystroke::parse("a").unwrap(),
4125        )
4126        .unwrap();
4127
4128        assert!(handled_action.get());
4129    }
4130
4131    #[crate::test(self)]
4132    async fn test_model_condition(mut cx: TestAppContext) {
4133        struct Counter(usize);
4134
4135        impl super::Entity for Counter {
4136            type Event = ();
4137        }
4138
4139        impl Counter {
4140            fn inc(&mut self, cx: &mut ModelContext<Self>) {
4141                self.0 += 1;
4142                cx.notify();
4143            }
4144        }
4145
4146        let model = cx.add_model(|_| Counter(0));
4147
4148        let condition1 = model.condition(&cx, |model, _| model.0 == 2);
4149        let condition2 = model.condition(&cx, |model, _| model.0 == 3);
4150        smol::pin!(condition1, condition2);
4151
4152        model.update(&mut cx, |model, cx| model.inc(cx));
4153        assert_eq!(poll_once(&mut condition1).await, None);
4154        assert_eq!(poll_once(&mut condition2).await, None);
4155
4156        model.update(&mut cx, |model, cx| model.inc(cx));
4157        assert_eq!(poll_once(&mut condition1).await, Some(()));
4158        assert_eq!(poll_once(&mut condition2).await, None);
4159
4160        model.update(&mut cx, |model, cx| model.inc(cx));
4161        assert_eq!(poll_once(&mut condition2).await, Some(()));
4162
4163        model.update(&mut cx, |_, cx| cx.notify());
4164    }
4165
4166    #[crate::test(self)]
4167    #[should_panic]
4168    async fn test_model_condition_timeout(mut cx: TestAppContext) {
4169        struct Model;
4170
4171        impl super::Entity for Model {
4172            type Event = ();
4173        }
4174
4175        let model = cx.add_model(|_| Model);
4176        model.condition(&cx, |_, _| false).await;
4177    }
4178
4179    #[crate::test(self)]
4180    #[should_panic(expected = "model dropped with pending condition")]
4181    async fn test_model_condition_panic_on_drop(mut cx: TestAppContext) {
4182        struct Model;
4183
4184        impl super::Entity for Model {
4185            type Event = ();
4186        }
4187
4188        let model = cx.add_model(|_| Model);
4189        let condition = model.condition(&cx, |_, _| false);
4190        cx.update(|_| drop(model));
4191        condition.await;
4192    }
4193
4194    #[crate::test(self)]
4195    async fn test_view_condition(mut cx: TestAppContext) {
4196        struct Counter(usize);
4197
4198        impl super::Entity for Counter {
4199            type Event = ();
4200        }
4201
4202        impl super::View for Counter {
4203            fn ui_name() -> &'static str {
4204                "test view"
4205            }
4206
4207            fn render(&mut self, _: &mut RenderContext<Self>) -> ElementBox {
4208                Empty::new().boxed()
4209            }
4210        }
4211
4212        impl Counter {
4213            fn inc(&mut self, cx: &mut ViewContext<Self>) {
4214                self.0 += 1;
4215                cx.notify();
4216            }
4217        }
4218
4219        let (_, view) = cx.add_window(|_| Counter(0));
4220
4221        let condition1 = view.condition(&cx, |view, _| view.0 == 2);
4222        let condition2 = view.condition(&cx, |view, _| view.0 == 3);
4223        smol::pin!(condition1, condition2);
4224
4225        view.update(&mut cx, |view, cx| view.inc(cx));
4226        assert_eq!(poll_once(&mut condition1).await, None);
4227        assert_eq!(poll_once(&mut condition2).await, None);
4228
4229        view.update(&mut cx, |view, cx| view.inc(cx));
4230        assert_eq!(poll_once(&mut condition1).await, Some(()));
4231        assert_eq!(poll_once(&mut condition2).await, None);
4232
4233        view.update(&mut cx, |view, cx| view.inc(cx));
4234        assert_eq!(poll_once(&mut condition2).await, Some(()));
4235        view.update(&mut cx, |_, cx| cx.notify());
4236    }
4237
4238    #[crate::test(self)]
4239    #[should_panic]
4240    async fn test_view_condition_timeout(mut cx: TestAppContext) {
4241        struct View;
4242
4243        impl super::Entity for View {
4244            type Event = ();
4245        }
4246
4247        impl super::View for View {
4248            fn ui_name() -> &'static str {
4249                "test view"
4250            }
4251
4252            fn render(&mut self, _: &mut RenderContext<Self>) -> ElementBox {
4253                Empty::new().boxed()
4254            }
4255        }
4256
4257        let (_, view) = cx.add_window(|_| View);
4258        view.condition(&cx, |_, _| false).await;
4259    }
4260
4261    #[crate::test(self)]
4262    #[should_panic(expected = "view dropped with pending condition")]
4263    async fn test_view_condition_panic_on_drop(mut cx: TestAppContext) {
4264        struct View;
4265
4266        impl super::Entity for View {
4267            type Event = ();
4268        }
4269
4270        impl super::View for View {
4271            fn ui_name() -> &'static str {
4272                "test view"
4273            }
4274
4275            fn render(&mut self, _: &mut RenderContext<Self>) -> ElementBox {
4276                Empty::new().boxed()
4277            }
4278        }
4279
4280        let window_id = cx.add_window(|_| View).0;
4281        let view = cx.add_view(window_id, |_| View);
4282
4283        let condition = view.condition(&cx, |_, _| false);
4284        cx.update(|_| drop(view));
4285        condition.await;
4286    }
4287}