1pub mod action;
   2mod callback_collection;
   3mod menu;
   4pub(crate) mod ref_counts;
   5#[cfg(any(test, feature = "test-support"))]
   6pub mod test_app_context;
   7pub(crate) mod window;
   8mod window_input_handler;
   9
  10use std::{
  11    any::{type_name, Any, TypeId},
  12    cell::RefCell,
  13    fmt::{self, Debug},
  14    hash::{Hash, Hasher},
  15    marker::PhantomData,
  16    mem,
  17    ops::{Deref, DerefMut, Range},
  18    path::{Path, PathBuf},
  19    pin::Pin,
  20    rc::{self, Rc},
  21    sync::{Arc, Weak},
  22    time::Duration,
  23};
  24
  25use anyhow::{anyhow, Context, Result};
  26use parking_lot::Mutex;
  27use postage::oneshot;
  28use smallvec::SmallVec;
  29use smol::prelude::*;
  30use util::ResultExt;
  31use uuid::Uuid;
  32
  33pub use action::*;
  34use callback_collection::CallbackCollection;
  35use collections::{hash_map::Entry, BTreeMap, HashMap, HashSet, VecDeque};
  36pub use menu::*;
  37use platform::Event;
  38#[cfg(any(test, feature = "test-support"))]
  39use ref_counts::LeakDetector;
  40#[cfg(any(test, feature = "test-support"))]
  41pub use test_app_context::{ContextHandle, TestAppContext};
  42use window_input_handler::WindowInputHandler;
  43
  44use crate::{
  45    elements::{AnyElement, AnyRootElement, RootElement},
  46    executor::{self, Task},
  47    json,
  48    keymap_matcher::{self, Binding, KeymapContext, KeymapMatcher, Keystroke, MatchResult},
  49    platform::{
  50        self, FontSystem, KeyDownEvent, KeyUpEvent, ModifiersChangedEvent, MouseButton,
  51        PathPromptOptions, Platform, PromptLevel, WindowBounds, WindowOptions,
  52    },
  53    util::post_inc,
  54    window::{Window, WindowContext},
  55    AssetCache, AssetSource, ClipboardItem, FontCache, MouseRegionId,
  56};
  57
  58use self::ref_counts::RefCounts;
  59
  60pub trait Entity: 'static {
  61    type Event;
  62
  63    fn release(&mut self, _: &mut AppContext) {}
  64    fn app_will_quit(
  65        &mut self,
  66        _: &mut AppContext,
  67    ) -> Option<Pin<Box<dyn 'static + Future<Output = ()>>>> {
  68        None
  69    }
  70}
  71
  72pub trait View: Entity + Sized {
  73    fn ui_name() -> &'static str;
  74    fn render(&mut self, cx: &mut ViewContext<'_, '_, Self>) -> AnyElement<Self>;
  75    fn focus_in(&mut self, _: AnyViewHandle, _: &mut ViewContext<Self>) {}
  76    fn focus_out(&mut self, _: AnyViewHandle, _: &mut ViewContext<Self>) {}
  77    fn key_down(&mut self, _: &KeyDownEvent, _: &mut ViewContext<Self>) -> bool {
  78        false
  79    }
  80    fn key_up(&mut self, _: &KeyUpEvent, _: &mut ViewContext<Self>) -> bool {
  81        false
  82    }
  83    fn modifiers_changed(&mut self, _: &ModifiersChangedEvent, _: &mut ViewContext<Self>) -> bool {
  84        false
  85    }
  86
  87    fn update_keymap_context(&self, keymap: &mut keymap_matcher::KeymapContext, _: &AppContext) {
  88        Self::reset_to_default_keymap_context(keymap);
  89    }
  90
  91    fn reset_to_default_keymap_context(keymap: &mut keymap_matcher::KeymapContext) {
  92        keymap.clear();
  93        keymap.add_identifier(Self::ui_name());
  94    }
  95
  96    fn debug_json(&self, _: &AppContext) -> serde_json::Value {
  97        serde_json::Value::Null
  98    }
  99
 100    fn text_for_range(&self, _: Range<usize>, _: &AppContext) -> Option<String> {
 101        None
 102    }
 103    fn selected_text_range(&self, _: &AppContext) -> Option<Range<usize>> {
 104        None
 105    }
 106    fn marked_text_range(&self, _: &AppContext) -> Option<Range<usize>> {
 107        None
 108    }
 109    fn unmark_text(&mut self, _: &mut ViewContext<Self>) {}
 110    fn replace_text_in_range(
 111        &mut self,
 112        _: Option<Range<usize>>,
 113        _: &str,
 114        _: &mut ViewContext<Self>,
 115    ) {
 116    }
 117    fn replace_and_mark_text_in_range(
 118        &mut self,
 119        _: Option<Range<usize>>,
 120        _: &str,
 121        _: Option<Range<usize>>,
 122        _: &mut ViewContext<Self>,
 123    ) {
 124    }
 125}
 126
 127pub trait BorrowAppContext {
 128    fn read_with<T, F: FnOnce(&AppContext) -> T>(&self, f: F) -> T;
 129    fn update<T, F: FnOnce(&mut AppContext) -> T>(&mut self, f: F) -> T;
 130}
 131
 132pub trait BorrowWindowContext {
 133    fn read_with<T, F: FnOnce(&WindowContext) -> T>(&self, window_id: usize, f: F) -> T;
 134    fn update<T, F: FnOnce(&mut WindowContext) -> T>(&mut self, window_id: usize, f: F) -> T;
 135}
 136
 137#[derive(Clone)]
 138pub struct App(Rc<RefCell<AppContext>>);
 139
 140impl App {
 141    pub fn new(asset_source: impl AssetSource) -> Result<Self> {
 142        let platform = platform::current::platform();
 143        let foreground = Rc::new(executor::Foreground::platform(platform.dispatcher())?);
 144        let foreground_platform = platform::current::foreground_platform(foreground.clone());
 145        let app = Self(Rc::new(RefCell::new(AppContext::new(
 146            foreground,
 147            Arc::new(executor::Background::new()),
 148            platform.clone(),
 149            foreground_platform.clone(),
 150            Arc::new(FontCache::new(platform.fonts())),
 151            Default::default(),
 152            asset_source,
 153        ))));
 154
 155        foreground_platform.on_quit(Box::new({
 156            let cx = app.0.clone();
 157            move || {
 158                cx.borrow_mut().quit();
 159            }
 160        }));
 161        setup_menu_handlers(foreground_platform.as_ref(), &app);
 162
 163        app.0.borrow_mut().weak_self = Some(Rc::downgrade(&app.0));
 164        Ok(app)
 165    }
 166
 167    pub fn background(&self) -> Arc<executor::Background> {
 168        self.0.borrow().background().clone()
 169    }
 170
 171    pub fn on_become_active<F>(self, mut callback: F) -> Self
 172    where
 173        F: 'static + FnMut(&mut AppContext),
 174    {
 175        let cx = self.0.clone();
 176        self.0
 177            .borrow_mut()
 178            .foreground_platform
 179            .on_become_active(Box::new(move || callback(&mut *cx.borrow_mut())));
 180        self
 181    }
 182
 183    pub fn on_resign_active<F>(self, mut callback: F) -> Self
 184    where
 185        F: 'static + FnMut(&mut AppContext),
 186    {
 187        let cx = self.0.clone();
 188        self.0
 189            .borrow_mut()
 190            .foreground_platform
 191            .on_resign_active(Box::new(move || callback(&mut *cx.borrow_mut())));
 192        self
 193    }
 194
 195    pub fn on_quit<F>(&mut self, mut callback: F) -> &mut Self
 196    where
 197        F: 'static + FnMut(&mut AppContext),
 198    {
 199        let cx = self.0.clone();
 200        self.0
 201            .borrow_mut()
 202            .foreground_platform
 203            .on_quit(Box::new(move || callback(&mut *cx.borrow_mut())));
 204        self
 205    }
 206
 207    /// Handle the application being re-activated when no windows are open.
 208    pub fn on_reopen<F>(&mut self, mut callback: F) -> &mut Self
 209    where
 210        F: 'static + FnMut(&mut AppContext),
 211    {
 212        let cx = self.0.clone();
 213        self.0
 214            .borrow_mut()
 215            .foreground_platform
 216            .on_reopen(Box::new(move || callback(&mut *cx.borrow_mut())));
 217        self
 218    }
 219
 220    pub fn on_event<F>(&mut self, mut callback: F) -> &mut Self
 221    where
 222        F: 'static + FnMut(Event, &mut AppContext) -> bool,
 223    {
 224        let cx = self.0.clone();
 225        self.0
 226            .borrow_mut()
 227            .foreground_platform
 228            .on_event(Box::new(move |event| {
 229                callback(event, &mut *cx.borrow_mut())
 230            }));
 231        self
 232    }
 233
 234    pub fn on_open_urls<F>(&mut self, mut callback: F) -> &mut Self
 235    where
 236        F: 'static + FnMut(Vec<String>, &mut AppContext),
 237    {
 238        let cx = self.0.clone();
 239        self.0
 240            .borrow_mut()
 241            .foreground_platform
 242            .on_open_urls(Box::new(move |urls| callback(urls, &mut *cx.borrow_mut())));
 243        self
 244    }
 245
 246    pub fn run<F>(self, on_finish_launching: F)
 247    where
 248        F: 'static + FnOnce(&mut AppContext),
 249    {
 250        let platform = self.0.borrow().foreground_platform.clone();
 251        platform.run(Box::new(move || {
 252            let mut cx = self.0.borrow_mut();
 253            let cx = &mut *cx;
 254            crate::views::init(cx);
 255            on_finish_launching(cx);
 256        }))
 257    }
 258
 259    pub fn platform(&self) -> Arc<dyn Platform> {
 260        self.0.borrow().platform.clone()
 261    }
 262
 263    pub fn font_cache(&self) -> Arc<FontCache> {
 264        self.0.borrow().font_cache.clone()
 265    }
 266
 267    fn update<T, F: FnOnce(&mut AppContext) -> T>(&mut self, callback: F) -> T {
 268        let mut state = self.0.borrow_mut();
 269        let result = state.update(callback);
 270        state.pending_notifications.clear();
 271        result
 272    }
 273
 274    fn update_window<T, F: FnOnce(&mut WindowContext) -> T>(
 275        &mut self,
 276        window_id: usize,
 277        callback: F,
 278    ) -> Option<T> {
 279        let mut state = self.0.borrow_mut();
 280        let result = state.update_window(window_id, callback);
 281        state.pending_notifications.clear();
 282        result
 283    }
 284}
 285
 286#[derive(Clone)]
 287pub struct AsyncAppContext(Rc<RefCell<AppContext>>);
 288
 289impl AsyncAppContext {
 290    pub fn spawn<F, Fut, T>(&self, f: F) -> Task<T>
 291    where
 292        F: FnOnce(AsyncAppContext) -> Fut,
 293        Fut: 'static + Future<Output = T>,
 294        T: 'static,
 295    {
 296        self.0.borrow().foreground.spawn(f(self.clone()))
 297    }
 298
 299    pub fn read<T, F: FnOnce(&AppContext) -> T>(&self, callback: F) -> T {
 300        callback(&*self.0.borrow())
 301    }
 302
 303    pub fn update<T, F: FnOnce(&mut AppContext) -> T>(&mut self, callback: F) -> T {
 304        self.0.borrow_mut().update(callback)
 305    }
 306
 307    pub fn read_window<T, F: FnOnce(&WindowContext) -> T>(
 308        &self,
 309        window_id: usize,
 310        callback: F,
 311    ) -> Option<T> {
 312        self.0.borrow_mut().read_window(window_id, callback)
 313    }
 314
 315    pub fn update_window<T, F: FnOnce(&mut WindowContext) -> T>(
 316        &mut self,
 317        window_id: usize,
 318        callback: F,
 319    ) -> Option<T> {
 320        self.0.borrow_mut().update_window(window_id, callback)
 321    }
 322
 323    pub fn debug_elements(&self, window_id: usize) -> Option<json::Value> {
 324        self.0.borrow().read_window(window_id, |cx| {
 325            let root_view = cx.window.root_view();
 326            let root_element = cx.window.rendered_views.get(&root_view.id())?;
 327            root_element.debug(cx).log_err()
 328        })?
 329    }
 330
 331    pub fn dispatch_action(
 332        &mut self,
 333        window_id: usize,
 334        view_id: usize,
 335        action: &dyn Action,
 336    ) -> Result<()> {
 337        self.0
 338            .borrow_mut()
 339            .update_window(window_id, |window| {
 340                window.dispatch_action(Some(view_id), action);
 341            })
 342            .ok_or_else(|| anyhow!("window not found"))
 343    }
 344
 345    pub fn available_actions(
 346        &self,
 347        window_id: usize,
 348        view_id: usize,
 349    ) -> Vec<(&'static str, Box<dyn Action>, SmallVec<[Binding; 1]>)> {
 350        self.read_window(window_id, |cx| cx.available_actions(view_id))
 351            .unwrap_or_default()
 352    }
 353
 354    pub fn has_window(&self, window_id: usize) -> bool {
 355        self.read(|cx| cx.windows.contains_key(&window_id))
 356    }
 357
 358    pub fn window_is_active(&self, window_id: usize) -> bool {
 359        self.read(|cx| cx.windows.get(&window_id).map_or(false, |w| w.is_active))
 360    }
 361
 362    pub fn root_view(&self, window_id: usize) -> Option<AnyViewHandle> {
 363        self.read(|cx| cx.windows.get(&window_id).map(|w| w.root_view().clone()))
 364    }
 365
 366    pub fn window_ids(&self) -> Vec<usize> {
 367        self.read(|cx| cx.windows.keys().copied().collect())
 368    }
 369
 370    pub fn add_model<T, F>(&mut self, build_model: F) -> ModelHandle<T>
 371    where
 372        T: Entity,
 373        F: FnOnce(&mut ModelContext<T>) -> T,
 374    {
 375        self.update(|cx| cx.add_model(build_model))
 376    }
 377
 378    pub fn add_window<T, F>(
 379        &mut self,
 380        window_options: WindowOptions,
 381        build_root_view: F,
 382    ) -> (usize, ViewHandle<T>)
 383    where
 384        T: View,
 385        F: FnOnce(&mut ViewContext<T>) -> T,
 386    {
 387        self.update(|cx| cx.add_window(window_options, build_root_view))
 388    }
 389
 390    pub fn remove_window(&mut self, window_id: usize) {
 391        self.update_window(window_id, |cx| cx.remove_window());
 392    }
 393
 394    pub fn activate_window(&mut self, window_id: usize) {
 395        self.update_window(window_id, |cx| cx.activate_window());
 396    }
 397
 398    // TODO: Can we eliminate this method and move it to WindowContext then call it with update_window?s
 399    pub fn prompt(
 400        &mut self,
 401        window_id: usize,
 402        level: PromptLevel,
 403        msg: &str,
 404        answers: &[&str],
 405    ) -> Option<oneshot::Receiver<usize>> {
 406        self.update_window(window_id, |cx| cx.prompt(level, msg, answers))
 407    }
 408
 409    pub fn platform(&self) -> Arc<dyn Platform> {
 410        self.0.borrow().platform().clone()
 411    }
 412
 413    pub fn foreground(&self) -> Rc<executor::Foreground> {
 414        self.0.borrow().foreground.clone()
 415    }
 416
 417    pub fn background(&self) -> Arc<executor::Background> {
 418        self.0.borrow().background.clone()
 419    }
 420}
 421
 422impl BorrowAppContext for AsyncAppContext {
 423    fn read_with<T, F: FnOnce(&AppContext) -> T>(&self, f: F) -> T {
 424        self.0.borrow().read_with(f)
 425    }
 426
 427    fn update<T, F: FnOnce(&mut AppContext) -> T>(&mut self, f: F) -> T {
 428        self.0.borrow_mut().update(f)
 429    }
 430}
 431
 432type ActionCallback = dyn FnMut(&mut dyn AnyView, &dyn Action, &mut WindowContext, usize);
 433type GlobalActionCallback = dyn FnMut(&dyn Action, &mut AppContext);
 434
 435type SubscriptionCallback = Box<dyn FnMut(&dyn Any, &mut AppContext) -> bool>;
 436type GlobalSubscriptionCallback = Box<dyn FnMut(&dyn Any, &mut AppContext)>;
 437type ObservationCallback = Box<dyn FnMut(&mut AppContext) -> bool>;
 438type GlobalObservationCallback = Box<dyn FnMut(&mut AppContext)>;
 439type FocusObservationCallback = Box<dyn FnMut(bool, &mut WindowContext) -> bool>;
 440type ReleaseObservationCallback = Box<dyn FnMut(&dyn Any, &mut AppContext)>;
 441type ActionObservationCallback = Box<dyn FnMut(TypeId, &mut AppContext)>;
 442type WindowActivationCallback = Box<dyn FnMut(bool, &mut WindowContext) -> bool>;
 443type WindowFullscreenCallback = Box<dyn FnMut(bool, &mut WindowContext) -> bool>;
 444type WindowBoundsCallback = Box<dyn FnMut(WindowBounds, Uuid, &mut WindowContext) -> bool>;
 445type KeystrokeCallback =
 446    Box<dyn FnMut(&Keystroke, &MatchResult, Option<&Box<dyn Action>>, &mut WindowContext) -> bool>;
 447type ActiveLabeledTasksCallback = Box<dyn FnMut(&mut AppContext) -> bool>;
 448type DeserializeActionCallback = fn(json: &str) -> anyhow::Result<Box<dyn Action>>;
 449type WindowShouldCloseSubscriptionCallback = Box<dyn FnMut(&mut AppContext) -> bool>;
 450
 451pub struct AppContext {
 452    models: HashMap<usize, Box<dyn AnyModel>>,
 453    views: HashMap<(usize, usize), Box<dyn AnyView>>,
 454    views_metadata: HashMap<(usize, usize), ViewMetadata>,
 455    windows: HashMap<usize, Window>,
 456    globals: HashMap<TypeId, Box<dyn Any>>,
 457    element_states: HashMap<ElementStateId, Box<dyn Any>>,
 458    background: Arc<executor::Background>,
 459    ref_counts: Arc<Mutex<RefCounts>>,
 460
 461    weak_self: Option<rc::Weak<RefCell<Self>>>,
 462    platform: Arc<dyn Platform>,
 463    foreground_platform: Rc<dyn platform::ForegroundPlatform>,
 464    pub asset_cache: Arc<AssetCache>,
 465    font_system: Arc<dyn FontSystem>,
 466    pub font_cache: Arc<FontCache>,
 467    action_deserializers: HashMap<&'static str, (TypeId, DeserializeActionCallback)>,
 468    capture_actions: HashMap<TypeId, HashMap<TypeId, Vec<Box<ActionCallback>>>>,
 469    // Entity Types -> { Action Types -> Action Handlers }
 470    actions: HashMap<TypeId, HashMap<TypeId, Vec<Box<ActionCallback>>>>,
 471    // Action Types -> Action Handlers
 472    global_actions: HashMap<TypeId, Box<GlobalActionCallback>>,
 473    keystroke_matcher: KeymapMatcher,
 474    next_entity_id: usize,
 475    next_window_id: usize,
 476    next_subscription_id: usize,
 477    frame_count: usize,
 478
 479    subscriptions: CallbackCollection<usize, SubscriptionCallback>,
 480    global_subscriptions: CallbackCollection<TypeId, GlobalSubscriptionCallback>,
 481    observations: CallbackCollection<usize, ObservationCallback>,
 482    global_observations: CallbackCollection<TypeId, GlobalObservationCallback>,
 483    focus_observations: CallbackCollection<usize, FocusObservationCallback>,
 484    release_observations: CallbackCollection<usize, ReleaseObservationCallback>,
 485    action_dispatch_observations: CallbackCollection<(), ActionObservationCallback>,
 486    window_activation_observations: CallbackCollection<usize, WindowActivationCallback>,
 487    window_fullscreen_observations: CallbackCollection<usize, WindowFullscreenCallback>,
 488    window_bounds_observations: CallbackCollection<usize, WindowBoundsCallback>,
 489    keystroke_observations: CallbackCollection<usize, KeystrokeCallback>,
 490    active_labeled_task_observations: CallbackCollection<(), ActiveLabeledTasksCallback>,
 491
 492    foreground: Rc<executor::Foreground>,
 493    pending_effects: VecDeque<Effect>,
 494    pending_notifications: HashSet<usize>,
 495    pending_global_notifications: HashSet<TypeId>,
 496    pending_flushes: usize,
 497    flushing_effects: bool,
 498    halt_action_dispatch: bool,
 499    next_labeled_task_id: usize,
 500    active_labeled_tasks: BTreeMap<usize, &'static str>,
 501}
 502
 503impl AppContext {
 504    fn new(
 505        foreground: Rc<executor::Foreground>,
 506        background: Arc<executor::Background>,
 507        platform: Arc<dyn platform::Platform>,
 508        foreground_platform: Rc<dyn platform::ForegroundPlatform>,
 509        font_cache: Arc<FontCache>,
 510        ref_counts: RefCounts,
 511        asset_source: impl AssetSource,
 512    ) -> Self {
 513        Self {
 514            models: Default::default(),
 515            views: Default::default(),
 516            views_metadata: Default::default(),
 517            windows: Default::default(),
 518            globals: Default::default(),
 519            element_states: Default::default(),
 520            ref_counts: Arc::new(Mutex::new(ref_counts)),
 521            background,
 522
 523            weak_self: None,
 524            font_system: platform.fonts(),
 525            platform,
 526            foreground_platform,
 527            font_cache,
 528            asset_cache: Arc::new(AssetCache::new(asset_source)),
 529            action_deserializers: Default::default(),
 530            capture_actions: Default::default(),
 531            actions: Default::default(),
 532            global_actions: Default::default(),
 533            keystroke_matcher: KeymapMatcher::default(),
 534            next_entity_id: 0,
 535            next_window_id: 0,
 536            next_subscription_id: 0,
 537            frame_count: 0,
 538            subscriptions: Default::default(),
 539            global_subscriptions: Default::default(),
 540            observations: Default::default(),
 541            focus_observations: Default::default(),
 542            release_observations: Default::default(),
 543            global_observations: Default::default(),
 544            window_activation_observations: Default::default(),
 545            window_fullscreen_observations: Default::default(),
 546            window_bounds_observations: Default::default(),
 547            keystroke_observations: Default::default(),
 548            action_dispatch_observations: Default::default(),
 549            active_labeled_task_observations: Default::default(),
 550            foreground,
 551            pending_effects: VecDeque::new(),
 552            pending_notifications: Default::default(),
 553            pending_global_notifications: Default::default(),
 554            pending_flushes: 0,
 555            flushing_effects: false,
 556            halt_action_dispatch: false,
 557            next_labeled_task_id: 0,
 558            active_labeled_tasks: Default::default(),
 559        }
 560    }
 561
 562    pub fn background(&self) -> &Arc<executor::Background> {
 563        &self.background
 564    }
 565
 566    pub fn font_cache(&self) -> &Arc<FontCache> {
 567        &self.font_cache
 568    }
 569
 570    pub fn platform(&self) -> &Arc<dyn Platform> {
 571        &self.platform
 572    }
 573
 574    pub fn has_global<T: 'static>(&self) -> bool {
 575        self.globals.contains_key(&TypeId::of::<T>())
 576    }
 577
 578    pub fn global<T: 'static>(&self) -> &T {
 579        if let Some(global) = self.globals.get(&TypeId::of::<T>()) {
 580            global.downcast_ref().unwrap()
 581        } else {
 582            panic!("no global has been added for {}", type_name::<T>());
 583        }
 584    }
 585
 586    pub fn upgrade(&self) -> App {
 587        App(self.weak_self.as_ref().unwrap().upgrade().unwrap())
 588    }
 589
 590    fn quit(&mut self) {
 591        let mut futures = Vec::new();
 592
 593        self.update(|cx| {
 594            for model_id in cx.models.keys().copied().collect::<Vec<_>>() {
 595                let mut model = cx.models.remove(&model_id).unwrap();
 596                futures.extend(model.app_will_quit(cx));
 597                cx.models.insert(model_id, model);
 598            }
 599
 600            for view_id in cx.views.keys().copied().collect::<Vec<_>>() {
 601                let mut view = cx.views.remove(&view_id).unwrap();
 602                futures.extend(view.app_will_quit(cx));
 603                cx.views.insert(view_id, view);
 604            }
 605        });
 606
 607        self.windows.clear();
 608        self.flush_effects();
 609
 610        let futures = futures::future::join_all(futures);
 611        if self
 612            .background
 613            .block_with_timeout(Duration::from_millis(100), futures)
 614            .is_err()
 615        {
 616            log::error!("timed out waiting on app_will_quit");
 617        }
 618    }
 619
 620    pub fn foreground(&self) -> &Rc<executor::Foreground> {
 621        &self.foreground
 622    }
 623
 624    pub fn deserialize_action(
 625        &self,
 626        name: &str,
 627        argument: Option<&str>,
 628    ) -> Result<Box<dyn Action>> {
 629        let callback = self
 630            .action_deserializers
 631            .get(name)
 632            .ok_or_else(|| anyhow!("unknown action {}", name))?
 633            .1;
 634        callback(argument.unwrap_or("{}"))
 635            .with_context(|| format!("invalid data for action {}", name))
 636    }
 637
 638    pub fn add_action<A, V, F, R>(&mut self, handler: F)
 639    where
 640        A: Action,
 641        V: View,
 642        F: 'static + FnMut(&mut V, &A, &mut ViewContext<V>) -> R,
 643    {
 644        self.add_action_internal(handler, false)
 645    }
 646
 647    pub fn capture_action<A, V, F>(&mut self, handler: F)
 648    where
 649        A: Action,
 650        V: View,
 651        F: 'static + FnMut(&mut V, &A, &mut ViewContext<V>),
 652    {
 653        self.add_action_internal(handler, true)
 654    }
 655
 656    fn add_action_internal<A, V, F, R>(&mut self, mut handler: F, capture: bool)
 657    where
 658        A: Action,
 659        V: View,
 660        F: 'static + FnMut(&mut V, &A, &mut ViewContext<V>) -> R,
 661    {
 662        let handler = Box::new(
 663            move |view: &mut dyn AnyView,
 664                  action: &dyn Action,
 665                  cx: &mut WindowContext,
 666                  view_id: usize| {
 667                let action = action.as_any().downcast_ref().unwrap();
 668                let mut cx = ViewContext::mutable(cx, view_id);
 669                handler(
 670                    view.as_any_mut()
 671                        .downcast_mut()
 672                        .expect("downcast is type safe"),
 673                    action,
 674                    &mut cx,
 675                );
 676            },
 677        );
 678
 679        self.action_deserializers
 680            .entry(A::qualified_name())
 681            .or_insert((TypeId::of::<A>(), A::from_json_str));
 682
 683        let actions = if capture {
 684            &mut self.capture_actions
 685        } else {
 686            &mut self.actions
 687        };
 688
 689        actions
 690            .entry(TypeId::of::<V>())
 691            .or_default()
 692            .entry(TypeId::of::<A>())
 693            .or_default()
 694            .push(handler);
 695    }
 696
 697    pub fn add_async_action<A, V, F>(&mut self, mut handler: F)
 698    where
 699        A: Action,
 700        V: View,
 701        F: 'static + FnMut(&mut V, &A, &mut ViewContext<V>) -> Option<Task<Result<()>>>,
 702    {
 703        self.add_action(move |view, action, cx| {
 704            if let Some(task) = handler(view, action, cx) {
 705                task.detach_and_log_err(cx);
 706            }
 707        })
 708    }
 709
 710    pub fn add_global_action<A, F>(&mut self, mut handler: F)
 711    where
 712        A: Action,
 713        F: 'static + FnMut(&A, &mut AppContext),
 714    {
 715        let handler = Box::new(move |action: &dyn Action, cx: &mut AppContext| {
 716            let action = action.as_any().downcast_ref().unwrap();
 717            handler(action, cx);
 718        });
 719
 720        self.action_deserializers
 721            .entry(A::qualified_name())
 722            .or_insert((TypeId::of::<A>(), A::from_json_str));
 723
 724        if self
 725            .global_actions
 726            .insert(TypeId::of::<A>(), handler)
 727            .is_some()
 728        {
 729            panic!(
 730                "registered multiple global handlers for {}",
 731                type_name::<A>()
 732            );
 733        }
 734    }
 735
 736    pub fn view_ui_name(&self, window_id: usize, view_id: usize) -> Option<&'static str> {
 737        Some(self.views.get(&(window_id, view_id))?.ui_name())
 738    }
 739
 740    pub fn view_type_id(&self, window_id: usize, view_id: usize) -> Option<TypeId> {
 741        self.views_metadata
 742            .get(&(window_id, view_id))
 743            .map(|metadata| metadata.type_id)
 744    }
 745
 746    pub fn active_labeled_tasks<'a>(
 747        &'a self,
 748    ) -> impl DoubleEndedIterator<Item = &'static str> + 'a {
 749        self.active_labeled_tasks.values().cloned()
 750    }
 751
 752    pub(crate) fn start_frame(&mut self) {
 753        self.frame_count += 1;
 754    }
 755
 756    pub fn update<T, F: FnOnce(&mut Self) -> T>(&mut self, callback: F) -> T {
 757        self.pending_flushes += 1;
 758        let result = callback(self);
 759        self.flush_effects();
 760        result
 761    }
 762
 763    pub fn read_window<T, F: FnOnce(&WindowContext) -> T>(
 764        &self,
 765        window_id: usize,
 766        callback: F,
 767    ) -> Option<T> {
 768        let window = self.windows.get(&window_id)?;
 769        let window_context = WindowContext::immutable(self, &window, window_id);
 770        Some(callback(&window_context))
 771    }
 772
 773    pub fn update_window<T, F: FnOnce(&mut WindowContext) -> T>(
 774        &mut self,
 775        window_id: usize,
 776        callback: F,
 777    ) -> Option<T> {
 778        self.update(|app_context| {
 779            let mut window = app_context.windows.remove(&window_id)?;
 780            let mut window_context = WindowContext::mutable(app_context, &mut window, window_id);
 781            let result = callback(&mut window_context);
 782            if !window_context.removed {
 783                app_context.windows.insert(window_id, window);
 784            }
 785            Some(result)
 786        })
 787    }
 788
 789    pub fn update_active_window<T, F: FnOnce(&mut WindowContext) -> T>(
 790        &mut self,
 791        callback: F,
 792    ) -> Option<T> {
 793        self.platform
 794            .main_window_id()
 795            .and_then(|id| self.update_window(id, callback))
 796    }
 797
 798    pub fn prompt_for_paths(
 799        &self,
 800        options: PathPromptOptions,
 801    ) -> oneshot::Receiver<Option<Vec<PathBuf>>> {
 802        self.foreground_platform.prompt_for_paths(options)
 803    }
 804
 805    pub fn prompt_for_new_path(&self, directory: &Path) -> oneshot::Receiver<Option<PathBuf>> {
 806        self.foreground_platform.prompt_for_new_path(directory)
 807    }
 808
 809    pub fn reveal_path(&self, path: &Path) {
 810        self.foreground_platform.reveal_path(path)
 811    }
 812
 813    pub fn emit_global<E: Any>(&mut self, payload: E) {
 814        self.pending_effects.push_back(Effect::GlobalEvent {
 815            payload: Box::new(payload),
 816        });
 817    }
 818
 819    pub fn subscribe<E, H, F>(&mut self, handle: &H, mut callback: F) -> Subscription
 820    where
 821        E: Entity,
 822        E::Event: 'static,
 823        H: Handle<E>,
 824        F: 'static + FnMut(H, &E::Event, &mut Self),
 825    {
 826        self.subscribe_internal(handle, move |handle, event, cx| {
 827            callback(handle, event, cx);
 828            true
 829        })
 830    }
 831
 832    pub fn subscribe_global<E, F>(&mut self, mut callback: F) -> Subscription
 833    where
 834        E: Any,
 835        F: 'static + FnMut(&E, &mut Self),
 836    {
 837        let subscription_id = post_inc(&mut self.next_subscription_id);
 838        let type_id = TypeId::of::<E>();
 839        self.pending_effects.push_back(Effect::GlobalSubscription {
 840            type_id,
 841            subscription_id,
 842            callback: Box::new(move |payload, cx| {
 843                let payload = payload.downcast_ref().expect("downcast is type safe");
 844                callback(payload, cx)
 845            }),
 846        });
 847        Subscription::GlobalSubscription(
 848            self.global_subscriptions
 849                .subscribe(type_id, subscription_id),
 850        )
 851    }
 852
 853    pub fn observe<E, H, F>(&mut self, handle: &H, mut callback: F) -> Subscription
 854    where
 855        E: Entity,
 856        E::Event: 'static,
 857        H: Handle<E>,
 858        F: 'static + FnMut(H, &mut Self),
 859    {
 860        self.observe_internal(handle, move |handle, cx| {
 861            callback(handle, cx);
 862            true
 863        })
 864    }
 865
 866    fn subscribe_internal<E, H, F>(&mut self, handle: &H, mut callback: F) -> Subscription
 867    where
 868        E: Entity,
 869        E::Event: 'static,
 870        H: Handle<E>,
 871        F: 'static + FnMut(H, &E::Event, &mut Self) -> bool,
 872    {
 873        let subscription_id = post_inc(&mut self.next_subscription_id);
 874        let emitter = handle.downgrade();
 875        self.pending_effects.push_back(Effect::Subscription {
 876            entity_id: handle.id(),
 877            subscription_id,
 878            callback: Box::new(move |payload, cx| {
 879                if let Some(emitter) = H::upgrade_from(&emitter, cx) {
 880                    let payload = payload.downcast_ref().expect("downcast is type safe");
 881                    callback(emitter, payload, cx)
 882                } else {
 883                    false
 884                }
 885            }),
 886        });
 887        Subscription::Subscription(self.subscriptions.subscribe(handle.id(), subscription_id))
 888    }
 889
 890    fn observe_internal<E, H, F>(&mut self, handle: &H, mut callback: F) -> Subscription
 891    where
 892        E: Entity,
 893        E::Event: 'static,
 894        H: Handle<E>,
 895        F: 'static + FnMut(H, &mut Self) -> bool,
 896    {
 897        let subscription_id = post_inc(&mut self.next_subscription_id);
 898        let observed = handle.downgrade();
 899        let entity_id = handle.id();
 900        self.pending_effects.push_back(Effect::Observation {
 901            entity_id,
 902            subscription_id,
 903            callback: Box::new(move |cx| {
 904                if let Some(observed) = H::upgrade_from(&observed, cx) {
 905                    callback(observed, cx)
 906                } else {
 907                    false
 908                }
 909            }),
 910        });
 911        Subscription::Observation(self.observations.subscribe(entity_id, subscription_id))
 912    }
 913
 914    fn observe_focus<F, V>(&mut self, handle: &ViewHandle<V>, mut callback: F) -> Subscription
 915    where
 916        F: 'static + FnMut(ViewHandle<V>, bool, &mut WindowContext) -> bool,
 917        V: View,
 918    {
 919        let subscription_id = post_inc(&mut self.next_subscription_id);
 920        let observed = handle.downgrade();
 921        let view_id = handle.id();
 922
 923        self.pending_effects.push_back(Effect::FocusObservation {
 924            view_id,
 925            subscription_id,
 926            callback: Box::new(move |focused, cx| {
 927                if let Some(observed) = observed.upgrade(cx) {
 928                    callback(observed, focused, cx)
 929                } else {
 930                    false
 931                }
 932            }),
 933        });
 934        Subscription::FocusObservation(self.focus_observations.subscribe(view_id, subscription_id))
 935    }
 936
 937    pub fn observe_global<G, F>(&mut self, mut observe: F) -> Subscription
 938    where
 939        G: Any,
 940        F: 'static + FnMut(&mut AppContext),
 941    {
 942        let type_id = TypeId::of::<G>();
 943        let id = post_inc(&mut self.next_subscription_id);
 944
 945        self.global_observations.add_callback(
 946            type_id,
 947            id,
 948            Box::new(move |cx: &mut AppContext| observe(cx)),
 949        );
 950        Subscription::GlobalObservation(self.global_observations.subscribe(type_id, id))
 951    }
 952
 953    pub fn observe_default_global<G, F>(&mut self, observe: F) -> Subscription
 954    where
 955        G: Any + Default,
 956        F: 'static + FnMut(&mut AppContext),
 957    {
 958        if !self.has_global::<G>() {
 959            self.set_global(G::default());
 960        }
 961        self.observe_global::<G, F>(observe)
 962    }
 963
 964    pub fn observe_release<E, H, F>(&mut self, handle: &H, callback: F) -> Subscription
 965    where
 966        E: Entity,
 967        E::Event: 'static,
 968        H: Handle<E>,
 969        F: 'static + FnOnce(&E, &mut Self),
 970    {
 971        let id = post_inc(&mut self.next_subscription_id);
 972        let mut callback = Some(callback);
 973        self.release_observations.add_callback(
 974            handle.id(),
 975            id,
 976            Box::new(move |released, cx| {
 977                let released = released.downcast_ref().unwrap();
 978                if let Some(callback) = callback.take() {
 979                    callback(released, cx)
 980                }
 981            }),
 982        );
 983        Subscription::ReleaseObservation(self.release_observations.subscribe(handle.id(), id))
 984    }
 985
 986    pub fn observe_actions<F>(&mut self, callback: F) -> Subscription
 987    where
 988        F: 'static + FnMut(TypeId, &mut AppContext),
 989    {
 990        let subscription_id = post_inc(&mut self.next_subscription_id);
 991        self.action_dispatch_observations
 992            .add_callback((), subscription_id, Box::new(callback));
 993        Subscription::ActionObservation(
 994            self.action_dispatch_observations
 995                .subscribe((), subscription_id),
 996        )
 997    }
 998
 999    fn observe_active_labeled_tasks<F>(&mut self, callback: F) -> Subscription
1000    where
1001        F: 'static + FnMut(&mut AppContext) -> bool,
1002    {
1003        let subscription_id = post_inc(&mut self.next_subscription_id);
1004        self.active_labeled_task_observations
1005            .add_callback((), subscription_id, Box::new(callback));
1006        Subscription::ActiveLabeledTasksObservation(
1007            self.active_labeled_task_observations
1008                .subscribe((), subscription_id),
1009        )
1010    }
1011
1012    pub fn defer(&mut self, callback: impl 'static + FnOnce(&mut AppContext)) {
1013        self.pending_effects.push_back(Effect::Deferred {
1014            callback: Box::new(callback),
1015            after_window_update: false,
1016        })
1017    }
1018
1019    pub fn after_window_update(&mut self, callback: impl 'static + FnOnce(&mut AppContext)) {
1020        self.pending_effects.push_back(Effect::Deferred {
1021            callback: Box::new(callback),
1022            after_window_update: true,
1023        })
1024    }
1025
1026    fn notify_model(&mut self, model_id: usize) {
1027        if self.pending_notifications.insert(model_id) {
1028            self.pending_effects
1029                .push_back(Effect::ModelNotification { model_id });
1030        }
1031    }
1032
1033    fn notify_view(&mut self, window_id: usize, view_id: usize) {
1034        if self.pending_notifications.insert(view_id) {
1035            self.pending_effects
1036                .push_back(Effect::ViewNotification { window_id, view_id });
1037        }
1038    }
1039
1040    fn notify_global(&mut self, type_id: TypeId) {
1041        if self.pending_global_notifications.insert(type_id) {
1042            self.pending_effects
1043                .push_back(Effect::GlobalNotification { type_id });
1044        }
1045    }
1046
1047    pub fn all_action_names<'a>(&'a self) -> impl Iterator<Item = &'static str> + 'a {
1048        self.action_deserializers.keys().copied()
1049    }
1050
1051    pub fn is_action_available(&self, action: &dyn Action) -> bool {
1052        let mut available_in_window = false;
1053        let action_type = action.as_any().type_id();
1054        if let Some(window_id) = self.platform.main_window_id() {
1055            available_in_window = self
1056                .read_window(window_id, |cx| {
1057                    if let Some(focused_view_id) = cx.focused_view_id() {
1058                        for view_id in cx.ancestors(focused_view_id) {
1059                            if let Some(view_metadata) =
1060                                cx.views_metadata.get(&(window_id, view_id))
1061                            {
1062                                if let Some(actions) = cx.actions.get(&view_metadata.type_id) {
1063                                    if actions.contains_key(&action_type) {
1064                                        return true;
1065                                    }
1066                                }
1067                            }
1068                        }
1069                    }
1070                    false
1071                })
1072                .unwrap_or(false);
1073        }
1074        available_in_window || self.global_actions.contains_key(&action_type)
1075    }
1076
1077    fn actions_mut(
1078        &mut self,
1079        capture_phase: bool,
1080    ) -> &mut HashMap<TypeId, HashMap<TypeId, Vec<Box<ActionCallback>>>> {
1081        if capture_phase {
1082            &mut self.capture_actions
1083        } else {
1084            &mut self.actions
1085        }
1086    }
1087
1088    fn dispatch_global_action_any(&mut self, action: &dyn Action) -> bool {
1089        self.update(|this| {
1090            if let Some((name, mut handler)) = this.global_actions.remove_entry(&action.id()) {
1091                handler(action, this);
1092                this.global_actions.insert(name, handler);
1093                true
1094            } else {
1095                false
1096            }
1097        })
1098    }
1099
1100    pub fn add_bindings<T: IntoIterator<Item = Binding>>(&mut self, bindings: T) {
1101        self.keystroke_matcher.add_bindings(bindings);
1102    }
1103
1104    pub fn clear_bindings(&mut self) {
1105        self.keystroke_matcher.clear_bindings();
1106    }
1107
1108    pub fn default_global<T: 'static + Default>(&mut self) -> &T {
1109        let type_id = TypeId::of::<T>();
1110        self.update(|this| {
1111            if let Entry::Vacant(entry) = this.globals.entry(type_id) {
1112                entry.insert(Box::new(T::default()));
1113                this.notify_global(type_id);
1114            }
1115        });
1116        self.globals.get(&type_id).unwrap().downcast_ref().unwrap()
1117    }
1118
1119    pub fn set_global<T: 'static>(&mut self, state: T) {
1120        self.update(|this| {
1121            let type_id = TypeId::of::<T>();
1122            this.globals.insert(type_id, Box::new(state));
1123            this.notify_global(type_id);
1124        });
1125    }
1126
1127    pub fn update_default_global<T, F, U>(&mut self, update: F) -> U
1128    where
1129        T: 'static + Default,
1130        F: FnOnce(&mut T, &mut AppContext) -> U,
1131    {
1132        self.update(|mut this| {
1133            Self::update_default_global_internal(&mut this, |global, cx| update(global, cx))
1134        })
1135    }
1136
1137    fn update_default_global_internal<C, T, F, U>(this: &mut C, update: F) -> U
1138    where
1139        C: DerefMut<Target = AppContext>,
1140        T: 'static + Default,
1141        F: FnOnce(&mut T, &mut C) -> U,
1142    {
1143        let type_id = TypeId::of::<T>();
1144        let mut state = this
1145            .globals
1146            .remove(&type_id)
1147            .unwrap_or_else(|| Box::new(T::default()));
1148        let result = update(state.downcast_mut().unwrap(), this);
1149        this.globals.insert(type_id, state);
1150        this.notify_global(type_id);
1151        result
1152    }
1153
1154    pub fn update_global<T, F, U>(&mut self, update: F) -> U
1155    where
1156        T: 'static,
1157        F: FnOnce(&mut T, &mut AppContext) -> U,
1158    {
1159        self.update(|mut this| {
1160            Self::update_global_internal(&mut this, |global, cx| update(global, cx))
1161        })
1162    }
1163
1164    fn update_global_internal<C, T, F, U>(this: &mut C, update: F) -> U
1165    where
1166        C: DerefMut<Target = AppContext>,
1167        T: 'static,
1168        F: FnOnce(&mut T, &mut C) -> U,
1169    {
1170        let type_id = TypeId::of::<T>();
1171        if let Some(mut state) = this.globals.remove(&type_id) {
1172            let result = update(state.downcast_mut().unwrap(), this);
1173            this.globals.insert(type_id, state);
1174            this.notify_global(type_id);
1175            result
1176        } else {
1177            panic!("no global added for {}", std::any::type_name::<T>());
1178        }
1179    }
1180
1181    pub fn clear_globals(&mut self) {
1182        self.globals.clear();
1183    }
1184
1185    pub fn remove_global<T: 'static>(&mut self) -> T {
1186        *self
1187            .globals
1188            .remove(&TypeId::of::<T>())
1189            .unwrap_or_else(|| panic!("no global added for {}", std::any::type_name::<T>()))
1190            .downcast()
1191            .unwrap()
1192    }
1193
1194    pub fn add_model<T, F>(&mut self, build_model: F) -> ModelHandle<T>
1195    where
1196        T: Entity,
1197        F: FnOnce(&mut ModelContext<T>) -> T,
1198    {
1199        self.update(|this| {
1200            let model_id = post_inc(&mut this.next_entity_id);
1201            let handle = ModelHandle::new(model_id, &this.ref_counts);
1202            let mut cx = ModelContext::new(this, model_id);
1203            let model = build_model(&mut cx);
1204            this.models.insert(model_id, Box::new(model));
1205            handle
1206        })
1207    }
1208
1209    pub fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T {
1210        if let Some(model) = self.models.get(&handle.model_id) {
1211            model
1212                .as_any()
1213                .downcast_ref()
1214                .expect("downcast is type safe")
1215        } else {
1216            panic!("circular model reference");
1217        }
1218    }
1219
1220    fn update_model<T: Entity, V>(
1221        &mut self,
1222        handle: &ModelHandle<T>,
1223        update: &mut dyn FnMut(&mut T, &mut ModelContext<T>) -> V,
1224    ) -> V {
1225        if let Some(mut model) = self.models.remove(&handle.model_id) {
1226            self.update(|this| {
1227                let mut cx = ModelContext::new(this, handle.model_id);
1228                let result = update(
1229                    model
1230                        .as_any_mut()
1231                        .downcast_mut()
1232                        .expect("downcast is type safe"),
1233                    &mut cx,
1234                );
1235                this.models.insert(handle.model_id, model);
1236                result
1237            })
1238        } else {
1239            panic!("circular model update");
1240        }
1241    }
1242
1243    fn upgrade_model_handle<T: Entity>(
1244        &self,
1245        handle: &WeakModelHandle<T>,
1246    ) -> Option<ModelHandle<T>> {
1247        if self.ref_counts.lock().is_entity_alive(handle.model_id) {
1248            Some(ModelHandle::new(handle.model_id, &self.ref_counts))
1249        } else {
1250            None
1251        }
1252    }
1253
1254    fn model_handle_is_upgradable<T: Entity>(&self, handle: &WeakModelHandle<T>) -> bool {
1255        self.ref_counts.lock().is_entity_alive(handle.model_id)
1256    }
1257
1258    fn upgrade_any_model_handle(&self, handle: &AnyWeakModelHandle) -> Option<AnyModelHandle> {
1259        if self.ref_counts.lock().is_entity_alive(handle.model_id) {
1260            Some(AnyModelHandle::new(
1261                handle.model_id,
1262                handle.model_type,
1263                self.ref_counts.clone(),
1264            ))
1265        } else {
1266            None
1267        }
1268    }
1269
1270    pub fn add_window<V, F>(
1271        &mut self,
1272        window_options: WindowOptions,
1273        build_root_view: F,
1274    ) -> (usize, ViewHandle<V>)
1275    where
1276        V: View,
1277        F: FnOnce(&mut ViewContext<V>) -> V,
1278    {
1279        self.update(|this| {
1280            let window_id = post_inc(&mut this.next_window_id);
1281            let platform_window =
1282                this.platform
1283                    .open_window(window_id, window_options, this.foreground.clone());
1284            let window = this.build_window(window_id, platform_window, build_root_view);
1285            let root_view = window.root_view().clone().downcast::<V>().unwrap();
1286            this.windows.insert(window_id, window);
1287            (window_id, root_view)
1288        })
1289    }
1290
1291    pub fn add_status_bar_item<V, F>(&mut self, build_root_view: F) -> (usize, ViewHandle<V>)
1292    where
1293        V: View,
1294        F: FnOnce(&mut ViewContext<V>) -> V,
1295    {
1296        self.update(|this| {
1297            let window_id = post_inc(&mut this.next_window_id);
1298            let platform_window = this.platform.add_status_item(window_id);
1299            let window = this.build_window(window_id, platform_window, build_root_view);
1300            let root_view = window.root_view().clone().downcast::<V>().unwrap();
1301
1302            this.windows.insert(window_id, window);
1303            this.update_window(window_id, |cx| {
1304                root_view.update(cx, |view, cx| view.focus_in(cx.handle().into_any(), cx))
1305            });
1306
1307            (window_id, root_view)
1308        })
1309    }
1310
1311    pub fn build_window<V, F>(
1312        &mut self,
1313        window_id: usize,
1314        mut platform_window: Box<dyn platform::Window>,
1315        build_root_view: F,
1316    ) -> Window
1317    where
1318        V: View,
1319        F: FnOnce(&mut ViewContext<V>) -> V,
1320    {
1321        {
1322            let mut app = self.upgrade();
1323
1324            platform_window.on_event(Box::new(move |event| {
1325                app.update_window(window_id, |cx| {
1326                    if let Event::KeyDown(KeyDownEvent { keystroke, .. }) = &event {
1327                        if cx.dispatch_keystroke(keystroke) {
1328                            return true;
1329                        }
1330                    }
1331
1332                    cx.dispatch_event(event, false)
1333                })
1334                .unwrap_or(false)
1335            }));
1336        }
1337
1338        {
1339            let mut app = self.upgrade();
1340            platform_window.on_active_status_change(Box::new(move |is_active| {
1341                app.update(|cx| cx.window_changed_active_status(window_id, is_active))
1342            }));
1343        }
1344
1345        {
1346            let mut app = self.upgrade();
1347            platform_window.on_resize(Box::new(move || {
1348                app.update(|cx| cx.window_was_resized(window_id))
1349            }));
1350        }
1351
1352        {
1353            let mut app = self.upgrade();
1354            platform_window.on_moved(Box::new(move || {
1355                app.update(|cx| cx.window_was_moved(window_id))
1356            }));
1357        }
1358
1359        {
1360            let mut app = self.upgrade();
1361            platform_window.on_fullscreen(Box::new(move |is_fullscreen| {
1362                app.update(|cx| cx.window_was_fullscreen_changed(window_id, is_fullscreen))
1363            }));
1364        }
1365
1366        {
1367            let mut app = self.upgrade();
1368            platform_window.on_close(Box::new(move || {
1369                app.update(|cx| cx.update_window(window_id, |cx| cx.remove_window()));
1370            }));
1371        }
1372
1373        {
1374            let mut app = self.upgrade();
1375            platform_window
1376                .on_appearance_changed(Box::new(move || app.update(|cx| cx.refresh_windows())));
1377        }
1378
1379        platform_window.set_input_handler(Box::new(WindowInputHandler {
1380            app: self.upgrade().0,
1381            window_id,
1382        }));
1383
1384        let mut window = Window::new(window_id, platform_window, self, build_root_view);
1385        let mut cx = WindowContext::mutable(self, &mut window, window_id);
1386        cx.layout(false).expect("initial layout should not error");
1387        let scene = cx.paint().expect("initial paint should not error");
1388        window.platform_window.present_scene(scene);
1389        window
1390    }
1391
1392    pub fn replace_root_view<V, F>(
1393        &mut self,
1394        window_id: usize,
1395        build_root_view: F,
1396    ) -> Option<ViewHandle<V>>
1397    where
1398        V: View,
1399        F: FnOnce(&mut ViewContext<V>) -> V,
1400    {
1401        self.update_window(window_id, |cx| cx.replace_root_view(build_root_view))
1402    }
1403
1404    pub fn read_view<T: View>(&self, handle: &ViewHandle<T>) -> &T {
1405        if let Some(view) = self.views.get(&(handle.window_id, handle.view_id)) {
1406            view.as_any().downcast_ref().expect("downcast is type safe")
1407        } else {
1408            panic!("circular view reference for type {}", type_name::<T>());
1409        }
1410    }
1411
1412    fn upgrade_view_handle<T: View>(&self, handle: &WeakViewHandle<T>) -> Option<ViewHandle<T>> {
1413        if self.ref_counts.lock().is_entity_alive(handle.view_id) {
1414            Some(ViewHandle::new(
1415                handle.window_id,
1416                handle.view_id,
1417                &self.ref_counts,
1418            ))
1419        } else {
1420            None
1421        }
1422    }
1423
1424    fn upgrade_any_view_handle(&self, handle: &AnyWeakViewHandle) -> Option<AnyViewHandle> {
1425        if self.ref_counts.lock().is_entity_alive(handle.view_id) {
1426            Some(AnyViewHandle::new(
1427                handle.window_id,
1428                handle.view_id,
1429                handle.view_type,
1430                self.ref_counts.clone(),
1431            ))
1432        } else {
1433            None
1434        }
1435    }
1436
1437    fn remove_dropped_entities(&mut self) {
1438        loop {
1439            let (dropped_models, dropped_views, dropped_element_states) =
1440                self.ref_counts.lock().take_dropped();
1441            if dropped_models.is_empty()
1442                && dropped_views.is_empty()
1443                && dropped_element_states.is_empty()
1444            {
1445                break;
1446            }
1447
1448            for model_id in dropped_models {
1449                self.subscriptions.remove(model_id);
1450                self.observations.remove(model_id);
1451                let mut model = self.models.remove(&model_id).unwrap();
1452                model.release(self);
1453                self.pending_effects
1454                    .push_back(Effect::ModelRelease { model_id, model });
1455            }
1456
1457            for (window_id, view_id) in dropped_views {
1458                self.subscriptions.remove(view_id);
1459                self.observations.remove(view_id);
1460                self.views_metadata.remove(&(window_id, view_id));
1461                let mut view = self.views.remove(&(window_id, view_id)).unwrap();
1462                view.release(self);
1463                let change_focus_to = self.windows.get_mut(&window_id).and_then(|window| {
1464                    window.parents.remove(&view_id);
1465                    window
1466                        .invalidation
1467                        .get_or_insert_with(Default::default)
1468                        .removed
1469                        .push(view_id);
1470                    if window.focused_view_id == Some(view_id) {
1471                        Some(window.root_view().id())
1472                    } else {
1473                        None
1474                    }
1475                });
1476
1477                if let Some(view_id) = change_focus_to {
1478                    self.pending_effects
1479                        .push_back(Effect::Focus(FocusEffect::View {
1480                            window_id,
1481                            view_id: Some(view_id),
1482                            is_forced: false,
1483                        }));
1484                }
1485
1486                self.pending_effects
1487                    .push_back(Effect::ViewRelease { view_id, view });
1488            }
1489
1490            for key in dropped_element_states {
1491                self.element_states.remove(&key);
1492            }
1493        }
1494    }
1495
1496    fn flush_effects(&mut self) {
1497        self.pending_flushes = self.pending_flushes.saturating_sub(1);
1498        let mut after_window_update_callbacks = Vec::new();
1499
1500        if !self.flushing_effects && self.pending_flushes == 0 {
1501            self.flushing_effects = true;
1502
1503            let mut refreshing = false;
1504            let mut updated_windows = HashSet::default();
1505            let mut focus_effects = HashMap::<usize, FocusEffect>::default();
1506            loop {
1507                self.remove_dropped_entities();
1508                if let Some(effect) = self.pending_effects.pop_front() {
1509                    match effect {
1510                        Effect::Subscription {
1511                            entity_id,
1512                            subscription_id,
1513                            callback,
1514                        } => self
1515                            .subscriptions
1516                            .add_callback(entity_id, subscription_id, callback),
1517
1518                        Effect::Event { entity_id, payload } => {
1519                            let mut subscriptions = self.subscriptions.clone();
1520                            subscriptions
1521                                .emit(entity_id, |callback| callback(payload.as_ref(), self))
1522                        }
1523
1524                        Effect::GlobalSubscription {
1525                            type_id,
1526                            subscription_id,
1527                            callback,
1528                        } => self.global_subscriptions.add_callback(
1529                            type_id,
1530                            subscription_id,
1531                            callback,
1532                        ),
1533
1534                        Effect::GlobalEvent { payload } => self.emit_global_event(payload),
1535
1536                        Effect::Observation {
1537                            entity_id,
1538                            subscription_id,
1539                            callback,
1540                        } => self
1541                            .observations
1542                            .add_callback(entity_id, subscription_id, callback),
1543
1544                        Effect::ModelNotification { model_id } => {
1545                            let mut observations = self.observations.clone();
1546                            observations.emit(model_id, |callback| callback(self));
1547                        }
1548
1549                        Effect::ViewNotification { window_id, view_id } => {
1550                            self.handle_view_notification_effect(window_id, view_id)
1551                        }
1552
1553                        Effect::GlobalNotification { type_id } => {
1554                            let mut subscriptions = self.global_observations.clone();
1555                            subscriptions.emit(type_id, |callback| {
1556                                callback(self);
1557                                true
1558                            });
1559                        }
1560
1561                        Effect::Deferred {
1562                            callback,
1563                            after_window_update,
1564                        } => {
1565                            if after_window_update {
1566                                after_window_update_callbacks.push(callback);
1567                            } else {
1568                                callback(self)
1569                            }
1570                        }
1571
1572                        Effect::ModelRelease { model_id, model } => {
1573                            self.handle_entity_release_effect(model_id, model.as_any())
1574                        }
1575
1576                        Effect::ViewRelease { view_id, view } => {
1577                            self.handle_entity_release_effect(view_id, view.as_any())
1578                        }
1579
1580                        Effect::Focus(mut effect) => {
1581                            if focus_effects
1582                                .get(&effect.window_id())
1583                                .map_or(false, |prev_effect| prev_effect.is_forced())
1584                            {
1585                                effect.force();
1586                            }
1587
1588                            focus_effects.insert(effect.window_id(), effect);
1589                        }
1590
1591                        Effect::FocusObservation {
1592                            view_id,
1593                            subscription_id,
1594                            callback,
1595                        } => {
1596                            self.focus_observations.add_callback(
1597                                view_id,
1598                                subscription_id,
1599                                callback,
1600                            );
1601                        }
1602
1603                        Effect::ResizeWindow { window_id } => {
1604                            if let Some(window) = self.windows.get_mut(&window_id) {
1605                                window
1606                                    .invalidation
1607                                    .get_or_insert(WindowInvalidation::default());
1608                            }
1609                            self.handle_window_moved(window_id);
1610                        }
1611
1612                        Effect::MoveWindow { window_id } => {
1613                            self.handle_window_moved(window_id);
1614                        }
1615
1616                        Effect::WindowActivationObservation {
1617                            window_id,
1618                            subscription_id,
1619                            callback,
1620                        } => self.window_activation_observations.add_callback(
1621                            window_id,
1622                            subscription_id,
1623                            callback,
1624                        ),
1625
1626                        Effect::ActivateWindow {
1627                            window_id,
1628                            is_active,
1629                        } => {
1630                            if self.handle_window_activation_effect(window_id, is_active)
1631                                && is_active
1632                            {
1633                                focus_effects
1634                                    .entry(window_id)
1635                                    .or_insert_with(|| FocusEffect::View {
1636                                        window_id,
1637                                        view_id: self
1638                                            .read_window(window_id, |cx| cx.focused_view_id())
1639                                            .flatten(),
1640                                        is_forced: true,
1641                                    })
1642                                    .force();
1643                            }
1644                        }
1645
1646                        Effect::WindowFullscreenObservation {
1647                            window_id,
1648                            subscription_id,
1649                            callback,
1650                        } => self.window_fullscreen_observations.add_callback(
1651                            window_id,
1652                            subscription_id,
1653                            callback,
1654                        ),
1655
1656                        Effect::FullscreenWindow {
1657                            window_id,
1658                            is_fullscreen,
1659                        } => self.handle_fullscreen_effect(window_id, is_fullscreen),
1660
1661                        Effect::WindowBoundsObservation {
1662                            window_id,
1663                            subscription_id,
1664                            callback,
1665                        } => self.window_bounds_observations.add_callback(
1666                            window_id,
1667                            subscription_id,
1668                            callback,
1669                        ),
1670
1671                        Effect::RefreshWindows => {
1672                            refreshing = true;
1673                        }
1674
1675                        Effect::ActionDispatchNotification { action_id } => {
1676                            self.handle_action_dispatch_notification_effect(action_id)
1677                        }
1678                        Effect::WindowShouldCloseSubscription {
1679                            window_id,
1680                            callback,
1681                        } => {
1682                            self.handle_window_should_close_subscription_effect(window_id, callback)
1683                        }
1684                        Effect::Keystroke {
1685                            window_id,
1686                            keystroke,
1687                            handled_by,
1688                            result,
1689                        } => self.handle_keystroke_effect(window_id, keystroke, handled_by, result),
1690                        Effect::ActiveLabeledTasksChanged => {
1691                            self.handle_active_labeled_tasks_changed_effect()
1692                        }
1693                        Effect::ActiveLabeledTasksObservation {
1694                            subscription_id,
1695                            callback,
1696                        } => self.active_labeled_task_observations.add_callback(
1697                            (),
1698                            subscription_id,
1699                            callback,
1700                        ),
1701                    }
1702                    self.pending_notifications.clear();
1703                } else {
1704                    for window_id in self.windows.keys().cloned().collect::<Vec<_>>() {
1705                        self.update_window(window_id, |cx| {
1706                            let invalidation = if refreshing {
1707                                let mut invalidation =
1708                                    cx.window.invalidation.take().unwrap_or_default();
1709                                invalidation
1710                                    .updated
1711                                    .extend(cx.window.rendered_views.keys().copied());
1712                                Some(invalidation)
1713                            } else {
1714                                cx.window.invalidation.take()
1715                            };
1716
1717                            if let Some(invalidation) = invalidation {
1718                                let appearance = cx.window.platform_window.appearance();
1719                                cx.invalidate(invalidation, appearance);
1720                                if cx.layout(refreshing).log_err().is_some() {
1721                                    updated_windows.insert(window_id);
1722                                }
1723                            }
1724                        });
1725                    }
1726
1727                    for (_, effect) in focus_effects.drain() {
1728                        self.handle_focus_effect(effect);
1729                    }
1730
1731                    if self.pending_effects.is_empty() {
1732                        for callback in after_window_update_callbacks.drain(..) {
1733                            callback(self);
1734                        }
1735
1736                        for window_id in updated_windows.drain() {
1737                            self.update_window(window_id, |cx| {
1738                                if let Some(scene) = cx.paint().log_err() {
1739                                    cx.window.platform_window.present_scene(scene);
1740                                }
1741                            });
1742                        }
1743
1744                        if self.pending_effects.is_empty() {
1745                            self.flushing_effects = false;
1746                            self.pending_notifications.clear();
1747                            self.pending_global_notifications.clear();
1748                            break;
1749                        }
1750                    }
1751
1752                    refreshing = false;
1753                }
1754            }
1755        }
1756    }
1757
1758    fn window_was_resized(&mut self, window_id: usize) {
1759        self.pending_effects
1760            .push_back(Effect::ResizeWindow { window_id });
1761    }
1762
1763    fn window_was_moved(&mut self, window_id: usize) {
1764        self.pending_effects
1765            .push_back(Effect::MoveWindow { window_id });
1766    }
1767
1768    fn window_was_fullscreen_changed(&mut self, window_id: usize, is_fullscreen: bool) {
1769        self.pending_effects.push_back(Effect::FullscreenWindow {
1770            window_id,
1771            is_fullscreen,
1772        });
1773    }
1774
1775    fn window_changed_active_status(&mut self, window_id: usize, is_active: bool) {
1776        self.pending_effects.push_back(Effect::ActivateWindow {
1777            window_id,
1778            is_active,
1779        });
1780    }
1781
1782    fn keystroke(
1783        &mut self,
1784        window_id: usize,
1785        keystroke: Keystroke,
1786        handled_by: Option<Box<dyn Action>>,
1787        result: MatchResult,
1788    ) {
1789        self.pending_effects.push_back(Effect::Keystroke {
1790            window_id,
1791            keystroke,
1792            handled_by,
1793            result,
1794        });
1795    }
1796
1797    pub fn refresh_windows(&mut self) {
1798        self.pending_effects.push_back(Effect::RefreshWindows);
1799    }
1800
1801    fn emit_global_event(&mut self, payload: Box<dyn Any>) {
1802        let type_id = (&*payload).type_id();
1803
1804        let mut subscriptions = self.global_subscriptions.clone();
1805        subscriptions.emit(type_id, |callback| {
1806            callback(payload.as_ref(), self);
1807            true //Always alive
1808        });
1809    }
1810
1811    fn handle_view_notification_effect(
1812        &mut self,
1813        observed_window_id: usize,
1814        observed_view_id: usize,
1815    ) {
1816        let view_key = (observed_window_id, observed_view_id);
1817        if let Some((view, mut view_metadata)) = self
1818            .views
1819            .remove(&view_key)
1820            .zip(self.views_metadata.remove(&view_key))
1821        {
1822            if let Some(window) = self.windows.get_mut(&observed_window_id) {
1823                window
1824                    .invalidation
1825                    .get_or_insert_with(Default::default)
1826                    .updated
1827                    .insert(observed_view_id);
1828            }
1829
1830            view.update_keymap_context(&mut view_metadata.keymap_context, self);
1831            self.views.insert(view_key, view);
1832            self.views_metadata.insert(view_key, view_metadata);
1833
1834            let mut observations = self.observations.clone();
1835            observations.emit(observed_view_id, |callback| callback(self));
1836        }
1837    }
1838
1839    fn handle_entity_release_effect(&mut self, entity_id: usize, entity: &dyn Any) {
1840        self.release_observations
1841            .clone()
1842            .emit(entity_id, |callback| {
1843                callback(entity, self);
1844                // Release observations happen one time. So clear the callback by returning false
1845                false
1846            })
1847    }
1848
1849    fn handle_fullscreen_effect(&mut self, window_id: usize, is_fullscreen: bool) {
1850        self.update_window(window_id, |cx| {
1851            cx.window.is_fullscreen = is_fullscreen;
1852
1853            let mut fullscreen_observations = cx.window_fullscreen_observations.clone();
1854            fullscreen_observations.emit(window_id, |callback| callback(is_fullscreen, cx));
1855
1856            if let Some(uuid) = cx.window_display_uuid() {
1857                let bounds = cx.window_bounds();
1858                let mut bounds_observations = cx.window_bounds_observations.clone();
1859                bounds_observations.emit(window_id, |callback| callback(bounds, uuid, cx));
1860            }
1861
1862            Some(())
1863        });
1864    }
1865
1866    fn handle_keystroke_effect(
1867        &mut self,
1868        window_id: usize,
1869        keystroke: Keystroke,
1870        handled_by: Option<Box<dyn Action>>,
1871        result: MatchResult,
1872    ) {
1873        self.update_window(window_id, |cx| {
1874            let mut observations = cx.keystroke_observations.clone();
1875            observations.emit(window_id, move |callback| {
1876                callback(&keystroke, &result, handled_by.as_ref(), cx)
1877            });
1878        });
1879    }
1880
1881    fn handle_window_activation_effect(&mut self, window_id: usize, active: bool) -> bool {
1882        self.update_window(window_id, |cx| {
1883            if cx.window.is_active == active {
1884                return false;
1885            }
1886            cx.window.is_active = active;
1887
1888            let mut observations = cx.window_activation_observations.clone();
1889            observations.emit(window_id, |callback| callback(active, cx));
1890            true
1891        })
1892        .unwrap_or(false)
1893    }
1894
1895    fn handle_focus_effect(&mut self, effect: FocusEffect) {
1896        let window_id = effect.window_id();
1897        self.update_window(window_id, |cx| {
1898            let focused_id = match effect {
1899                FocusEffect::View { view_id, .. } => view_id,
1900                FocusEffect::ViewParent { view_id, .. } => cx.ancestors(view_id).skip(1).next(),
1901            };
1902
1903            let focus_changed = cx.window.focused_view_id != focused_id;
1904            let blurred_id = cx.window.focused_view_id;
1905            cx.window.focused_view_id = focused_id;
1906
1907            if focus_changed {
1908                if let Some(blurred_id) = blurred_id {
1909                    for view_id in cx.ancestors(blurred_id).collect::<Vec<_>>() {
1910                        if let Some(mut view) = cx.views.remove(&(window_id, view_id)) {
1911                            view.focus_out(blurred_id, cx, view_id);
1912                            cx.views.insert((window_id, view_id), view);
1913                        }
1914                    }
1915
1916                    let mut subscriptions = cx.focus_observations.clone();
1917                    subscriptions.emit(blurred_id, |callback| callback(false, cx));
1918                }
1919            }
1920
1921            if focus_changed || effect.is_forced() {
1922                if let Some(focused_id) = focused_id {
1923                    for view_id in cx.ancestors(focused_id).collect::<Vec<_>>() {
1924                        if let Some(mut view) = cx.views.remove(&(window_id, view_id)) {
1925                            view.focus_in(focused_id, cx, view_id);
1926                            cx.views.insert((window_id, view_id), view);
1927                        }
1928                    }
1929
1930                    let mut subscriptions = cx.focus_observations.clone();
1931                    subscriptions.emit(focused_id, |callback| callback(true, cx));
1932                }
1933            }
1934        });
1935    }
1936
1937    fn handle_action_dispatch_notification_effect(&mut self, action_id: TypeId) {
1938        self.action_dispatch_observations
1939            .clone()
1940            .emit((), |callback| {
1941                callback(action_id, self);
1942                true
1943            });
1944    }
1945
1946    fn handle_window_should_close_subscription_effect(
1947        &mut self,
1948        window_id: usize,
1949        mut callback: WindowShouldCloseSubscriptionCallback,
1950    ) {
1951        let mut app = self.upgrade();
1952        if let Some(window) = self.windows.get_mut(&window_id) {
1953            window
1954                .platform_window
1955                .on_should_close(Box::new(move || app.update(|cx| callback(cx))))
1956        }
1957    }
1958
1959    fn handle_window_moved(&mut self, window_id: usize) {
1960        self.update_window(window_id, |cx| {
1961            if let Some(display) = cx.window_display_uuid() {
1962                let bounds = cx.window_bounds();
1963                cx.window_bounds_observations
1964                    .clone()
1965                    .emit(window_id, move |callback| {
1966                        callback(bounds, display, cx);
1967                        true
1968                    });
1969            }
1970        });
1971    }
1972
1973    fn handle_active_labeled_tasks_changed_effect(&mut self) {
1974        self.active_labeled_task_observations
1975            .clone()
1976            .emit((), move |callback| {
1977                callback(self);
1978                true
1979            });
1980    }
1981
1982    pub fn focus(&mut self, window_id: usize, view_id: Option<usize>) {
1983        self.pending_effects
1984            .push_back(Effect::Focus(FocusEffect::View {
1985                window_id,
1986                view_id,
1987                is_forced: false,
1988            }));
1989    }
1990
1991    fn spawn_internal<F, Fut, T>(&mut self, task_name: Option<&'static str>, f: F) -> Task<T>
1992    where
1993        F: FnOnce(AsyncAppContext) -> Fut,
1994        Fut: 'static + Future<Output = T>,
1995        T: 'static,
1996    {
1997        let label_id = task_name.map(|task_name| {
1998            let id = post_inc(&mut self.next_labeled_task_id);
1999            self.active_labeled_tasks.insert(id, task_name);
2000            self.pending_effects
2001                .push_back(Effect::ActiveLabeledTasksChanged);
2002            id
2003        });
2004
2005        let future = f(self.to_async());
2006        let cx = self.to_async();
2007        self.foreground.spawn(async move {
2008            let result = future.await;
2009            let mut cx = cx.0.borrow_mut();
2010
2011            if let Some(completed_label_id) = label_id {
2012                cx.active_labeled_tasks.remove(&completed_label_id);
2013                cx.pending_effects
2014                    .push_back(Effect::ActiveLabeledTasksChanged);
2015            }
2016            cx.flush_effects();
2017            result
2018        })
2019    }
2020
2021    pub fn spawn_labeled<F, Fut, T>(&mut self, task_name: &'static str, f: F) -> Task<T>
2022    where
2023        F: FnOnce(AsyncAppContext) -> Fut,
2024        Fut: 'static + Future<Output = T>,
2025        T: 'static,
2026    {
2027        self.spawn_internal(Some(task_name), f)
2028    }
2029
2030    pub fn spawn<F, Fut, T>(&mut self, f: F) -> Task<T>
2031    where
2032        F: FnOnce(AsyncAppContext) -> Fut,
2033        Fut: 'static + Future<Output = T>,
2034        T: 'static,
2035    {
2036        self.spawn_internal(None, f)
2037    }
2038
2039    pub fn to_async(&self) -> AsyncAppContext {
2040        AsyncAppContext(self.weak_self.as_ref().unwrap().upgrade().unwrap())
2041    }
2042
2043    pub fn write_to_clipboard(&self, item: ClipboardItem) {
2044        self.platform.write_to_clipboard(item);
2045    }
2046
2047    pub fn read_from_clipboard(&self) -> Option<ClipboardItem> {
2048        self.platform.read_from_clipboard()
2049    }
2050
2051    #[cfg(any(test, feature = "test-support"))]
2052    pub fn leak_detector(&self) -> Arc<Mutex<LeakDetector>> {
2053        self.ref_counts.lock().leak_detector.clone()
2054    }
2055}
2056
2057impl BorrowAppContext for AppContext {
2058    fn read_with<T, F: FnOnce(&AppContext) -> T>(&self, f: F) -> T {
2059        f(self)
2060    }
2061
2062    fn update<T, F: FnOnce(&mut AppContext) -> T>(&mut self, f: F) -> T {
2063        f(self)
2064    }
2065}
2066
2067#[derive(Debug)]
2068pub enum ParentId {
2069    View(usize),
2070    Root,
2071}
2072
2073struct ViewMetadata {
2074    type_id: TypeId,
2075    keymap_context: KeymapContext,
2076}
2077
2078#[derive(Default, Clone)]
2079pub struct WindowInvalidation {
2080    pub updated: HashSet<usize>,
2081    pub removed: Vec<usize>,
2082}
2083
2084#[derive(Debug)]
2085pub enum FocusEffect {
2086    View {
2087        window_id: usize,
2088        view_id: Option<usize>,
2089        is_forced: bool,
2090    },
2091    ViewParent {
2092        window_id: usize,
2093        view_id: usize,
2094        is_forced: bool,
2095    },
2096}
2097
2098impl FocusEffect {
2099    fn window_id(&self) -> usize {
2100        match self {
2101            FocusEffect::View { window_id, .. } => *window_id,
2102            FocusEffect::ViewParent { window_id, .. } => *window_id,
2103        }
2104    }
2105
2106    fn is_forced(&self) -> bool {
2107        match self {
2108            FocusEffect::View { is_forced, .. } => *is_forced,
2109            FocusEffect::ViewParent { is_forced, .. } => *is_forced,
2110        }
2111    }
2112
2113    fn force(&mut self) {
2114        match self {
2115            FocusEffect::View { is_forced, .. } => *is_forced = true,
2116            FocusEffect::ViewParent { is_forced, .. } => *is_forced = true,
2117        }
2118    }
2119}
2120
2121pub enum Effect {
2122    Subscription {
2123        entity_id: usize,
2124        subscription_id: usize,
2125        callback: SubscriptionCallback,
2126    },
2127    Event {
2128        entity_id: usize,
2129        payload: Box<dyn Any>,
2130    },
2131    GlobalSubscription {
2132        type_id: TypeId,
2133        subscription_id: usize,
2134        callback: GlobalSubscriptionCallback,
2135    },
2136    GlobalEvent {
2137        payload: Box<dyn Any>,
2138    },
2139    Observation {
2140        entity_id: usize,
2141        subscription_id: usize,
2142        callback: ObservationCallback,
2143    },
2144    ModelNotification {
2145        model_id: usize,
2146    },
2147    ViewNotification {
2148        window_id: usize,
2149        view_id: usize,
2150    },
2151    Deferred {
2152        callback: Box<dyn FnOnce(&mut AppContext)>,
2153        after_window_update: bool,
2154    },
2155    GlobalNotification {
2156        type_id: TypeId,
2157    },
2158    ModelRelease {
2159        model_id: usize,
2160        model: Box<dyn AnyModel>,
2161    },
2162    ViewRelease {
2163        view_id: usize,
2164        view: Box<dyn AnyView>,
2165    },
2166    Focus(FocusEffect),
2167    FocusObservation {
2168        view_id: usize,
2169        subscription_id: usize,
2170        callback: FocusObservationCallback,
2171    },
2172    ResizeWindow {
2173        window_id: usize,
2174    },
2175    MoveWindow {
2176        window_id: usize,
2177    },
2178    ActivateWindow {
2179        window_id: usize,
2180        is_active: bool,
2181    },
2182    WindowActivationObservation {
2183        window_id: usize,
2184        subscription_id: usize,
2185        callback: WindowActivationCallback,
2186    },
2187    FullscreenWindow {
2188        window_id: usize,
2189        is_fullscreen: bool,
2190    },
2191    WindowFullscreenObservation {
2192        window_id: usize,
2193        subscription_id: usize,
2194        callback: WindowFullscreenCallback,
2195    },
2196    WindowBoundsObservation {
2197        window_id: usize,
2198        subscription_id: usize,
2199        callback: WindowBoundsCallback,
2200    },
2201    Keystroke {
2202        window_id: usize,
2203        keystroke: Keystroke,
2204        handled_by: Option<Box<dyn Action>>,
2205        result: MatchResult,
2206    },
2207    RefreshWindows,
2208    ActionDispatchNotification {
2209        action_id: TypeId,
2210    },
2211    WindowShouldCloseSubscription {
2212        window_id: usize,
2213        callback: WindowShouldCloseSubscriptionCallback,
2214    },
2215    ActiveLabeledTasksChanged,
2216    ActiveLabeledTasksObservation {
2217        subscription_id: usize,
2218        callback: ActiveLabeledTasksCallback,
2219    },
2220}
2221
2222impl Debug for Effect {
2223    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2224        match self {
2225            Effect::Subscription {
2226                entity_id,
2227                subscription_id,
2228                ..
2229            } => f
2230                .debug_struct("Effect::Subscribe")
2231                .field("entity_id", entity_id)
2232                .field("subscription_id", subscription_id)
2233                .finish(),
2234            Effect::Event { entity_id, .. } => f
2235                .debug_struct("Effect::Event")
2236                .field("entity_id", entity_id)
2237                .finish(),
2238            Effect::GlobalSubscription {
2239                type_id,
2240                subscription_id,
2241                ..
2242            } => f
2243                .debug_struct("Effect::Subscribe")
2244                .field("type_id", type_id)
2245                .field("subscription_id", subscription_id)
2246                .finish(),
2247            Effect::GlobalEvent { payload, .. } => f
2248                .debug_struct("Effect::GlobalEvent")
2249                .field("type_id", &(&*payload).type_id())
2250                .finish(),
2251            Effect::Observation {
2252                entity_id,
2253                subscription_id,
2254                ..
2255            } => f
2256                .debug_struct("Effect::Observation")
2257                .field("entity_id", entity_id)
2258                .field("subscription_id", subscription_id)
2259                .finish(),
2260            Effect::ModelNotification { model_id } => f
2261                .debug_struct("Effect::ModelNotification")
2262                .field("model_id", model_id)
2263                .finish(),
2264            Effect::ViewNotification { window_id, view_id } => f
2265                .debug_struct("Effect::ViewNotification")
2266                .field("window_id", window_id)
2267                .field("view_id", view_id)
2268                .finish(),
2269            Effect::GlobalNotification { type_id } => f
2270                .debug_struct("Effect::GlobalNotification")
2271                .field("type_id", type_id)
2272                .finish(),
2273            Effect::Deferred { .. } => f.debug_struct("Effect::Deferred").finish(),
2274            Effect::ModelRelease { model_id, .. } => f
2275                .debug_struct("Effect::ModelRelease")
2276                .field("model_id", model_id)
2277                .finish(),
2278            Effect::ViewRelease { view_id, .. } => f
2279                .debug_struct("Effect::ViewRelease")
2280                .field("view_id", view_id)
2281                .finish(),
2282            Effect::Focus(focus) => f.debug_tuple("Effect::Focus").field(focus).finish(),
2283            Effect::FocusObservation {
2284                view_id,
2285                subscription_id,
2286                ..
2287            } => f
2288                .debug_struct("Effect::FocusObservation")
2289                .field("view_id", view_id)
2290                .field("subscription_id", subscription_id)
2291                .finish(),
2292            Effect::ActionDispatchNotification { action_id, .. } => f
2293                .debug_struct("Effect::ActionDispatchNotification")
2294                .field("action_id", action_id)
2295                .finish(),
2296            Effect::ResizeWindow { window_id } => f
2297                .debug_struct("Effect::RefreshWindow")
2298                .field("window_id", window_id)
2299                .finish(),
2300            Effect::MoveWindow { window_id } => f
2301                .debug_struct("Effect::MoveWindow")
2302                .field("window_id", window_id)
2303                .finish(),
2304            Effect::WindowActivationObservation {
2305                window_id,
2306                subscription_id,
2307                ..
2308            } => f
2309                .debug_struct("Effect::WindowActivationObservation")
2310                .field("window_id", window_id)
2311                .field("subscription_id", subscription_id)
2312                .finish(),
2313            Effect::ActivateWindow {
2314                window_id,
2315                is_active,
2316            } => f
2317                .debug_struct("Effect::ActivateWindow")
2318                .field("window_id", window_id)
2319                .field("is_active", is_active)
2320                .finish(),
2321            Effect::FullscreenWindow {
2322                window_id,
2323                is_fullscreen,
2324            } => f
2325                .debug_struct("Effect::FullscreenWindow")
2326                .field("window_id", window_id)
2327                .field("is_fullscreen", is_fullscreen)
2328                .finish(),
2329            Effect::WindowFullscreenObservation {
2330                window_id,
2331                subscription_id,
2332                callback: _,
2333            } => f
2334                .debug_struct("Effect::WindowFullscreenObservation")
2335                .field("window_id", window_id)
2336                .field("subscription_id", subscription_id)
2337                .finish(),
2338
2339            Effect::WindowBoundsObservation {
2340                window_id,
2341                subscription_id,
2342                callback: _,
2343            } => f
2344                .debug_struct("Effect::WindowBoundsObservation")
2345                .field("window_id", window_id)
2346                .field("subscription_id", subscription_id)
2347                .finish(),
2348            Effect::RefreshWindows => f.debug_struct("Effect::FullViewRefresh").finish(),
2349            Effect::WindowShouldCloseSubscription { window_id, .. } => f
2350                .debug_struct("Effect::WindowShouldCloseSubscription")
2351                .field("window_id", window_id)
2352                .finish(),
2353            Effect::Keystroke {
2354                window_id,
2355                keystroke,
2356                handled_by,
2357                result,
2358            } => f
2359                .debug_struct("Effect::Keystroke")
2360                .field("window_id", window_id)
2361                .field("keystroke", keystroke)
2362                .field(
2363                    "keystroke",
2364                    &handled_by.as_ref().map(|handled_by| handled_by.name()),
2365                )
2366                .field("result", result)
2367                .finish(),
2368            Effect::ActiveLabeledTasksChanged => {
2369                f.debug_struct("Effect::ActiveLabeledTasksChanged").finish()
2370            }
2371            Effect::ActiveLabeledTasksObservation {
2372                subscription_id,
2373                callback: _,
2374            } => f
2375                .debug_struct("Effect::ActiveLabeledTasksObservation")
2376                .field("subscription_id", subscription_id)
2377                .finish(),
2378        }
2379    }
2380}
2381
2382pub trait AnyModel {
2383    fn as_any(&self) -> &dyn Any;
2384    fn as_any_mut(&mut self) -> &mut dyn Any;
2385    fn release(&mut self, cx: &mut AppContext);
2386    fn app_will_quit(
2387        &mut self,
2388        cx: &mut AppContext,
2389    ) -> Option<Pin<Box<dyn 'static + Future<Output = ()>>>>;
2390}
2391
2392impl<T> AnyModel for T
2393where
2394    T: Entity,
2395{
2396    fn as_any(&self) -> &dyn Any {
2397        self
2398    }
2399
2400    fn as_any_mut(&mut self) -> &mut dyn Any {
2401        self
2402    }
2403
2404    fn release(&mut self, cx: &mut AppContext) {
2405        self.release(cx);
2406    }
2407
2408    fn app_will_quit(
2409        &mut self,
2410        cx: &mut AppContext,
2411    ) -> Option<Pin<Box<dyn 'static + Future<Output = ()>>>> {
2412        self.app_will_quit(cx)
2413    }
2414}
2415
2416pub trait AnyView {
2417    fn as_any(&self) -> &dyn Any;
2418    fn as_any_mut(&mut self) -> &mut dyn Any;
2419    fn release(&mut self, cx: &mut AppContext);
2420    fn app_will_quit(
2421        &mut self,
2422        cx: &mut AppContext,
2423    ) -> Option<Pin<Box<dyn 'static + Future<Output = ()>>>>;
2424    fn ui_name(&self) -> &'static str;
2425    fn render(&mut self, cx: &mut WindowContext, view_id: usize) -> Box<dyn AnyRootElement>;
2426    fn focus_in<'a, 'b>(&mut self, focused_id: usize, cx: &mut WindowContext<'a>, view_id: usize);
2427    fn focus_out(&mut self, focused_id: usize, cx: &mut WindowContext, view_id: usize);
2428    fn key_down(&mut self, event: &KeyDownEvent, cx: &mut WindowContext, view_id: usize) -> bool;
2429    fn key_up(&mut self, event: &KeyUpEvent, cx: &mut WindowContext, view_id: usize) -> bool;
2430    fn modifiers_changed(
2431        &mut self,
2432        event: &ModifiersChangedEvent,
2433        cx: &mut WindowContext,
2434        view_id: usize,
2435    ) -> bool;
2436    fn update_keymap_context(&self, keymap: &mut KeymapContext, cx: &AppContext);
2437    fn debug_json(&self, cx: &WindowContext) -> serde_json::Value;
2438
2439    fn text_for_range(&self, range: Range<usize>, cx: &WindowContext) -> Option<String>;
2440    fn selected_text_range(&self, cx: &WindowContext) -> Option<Range<usize>>;
2441    fn marked_text_range(&self, cx: &WindowContext) -> Option<Range<usize>>;
2442    fn unmark_text(&mut self, cx: &mut WindowContext, view_id: usize);
2443    fn replace_text_in_range(
2444        &mut self,
2445        range: Option<Range<usize>>,
2446        text: &str,
2447        cx: &mut WindowContext,
2448        view_id: usize,
2449    );
2450    fn replace_and_mark_text_in_range(
2451        &mut self,
2452        range: Option<Range<usize>>,
2453        new_text: &str,
2454        new_selected_range: Option<Range<usize>>,
2455        cx: &mut WindowContext,
2456        view_id: usize,
2457    );
2458    fn any_handle(&self, window_id: usize, view_id: usize, cx: &AppContext) -> AnyViewHandle {
2459        AnyViewHandle::new(
2460            window_id,
2461            view_id,
2462            self.as_any().type_id(),
2463            cx.ref_counts.clone(),
2464        )
2465    }
2466}
2467
2468impl<V> AnyView for V
2469where
2470    V: View,
2471{
2472    fn as_any(&self) -> &dyn Any {
2473        self
2474    }
2475
2476    fn as_any_mut(&mut self) -> &mut dyn Any {
2477        self
2478    }
2479
2480    fn release(&mut self, cx: &mut AppContext) {
2481        self.release(cx);
2482    }
2483
2484    fn app_will_quit(
2485        &mut self,
2486        cx: &mut AppContext,
2487    ) -> Option<Pin<Box<dyn 'static + Future<Output = ()>>>> {
2488        self.app_will_quit(cx)
2489    }
2490
2491    fn ui_name(&self) -> &'static str {
2492        V::ui_name()
2493    }
2494
2495    fn render(&mut self, cx: &mut WindowContext, view_id: usize) -> Box<dyn AnyRootElement> {
2496        let mut view_context = ViewContext::mutable(cx, view_id);
2497        let element = V::render(self, &mut view_context);
2498        let view = WeakViewHandle::new(cx.window_id, view_id);
2499        Box::new(RootElement::new(element, view))
2500    }
2501
2502    fn focus_in(&mut self, focused_id: usize, cx: &mut WindowContext, view_id: usize) {
2503        let mut cx = ViewContext::mutable(cx, view_id);
2504        let focused_view_handle: AnyViewHandle = if view_id == focused_id {
2505            cx.handle().into_any()
2506        } else {
2507            let focused_type = cx
2508                .views_metadata
2509                .get(&(cx.window_id, focused_id))
2510                .unwrap()
2511                .type_id;
2512            AnyViewHandle::new(
2513                cx.window_id,
2514                focused_id,
2515                focused_type,
2516                cx.ref_counts.clone(),
2517            )
2518        };
2519        View::focus_in(self, focused_view_handle, &mut cx);
2520    }
2521
2522    fn focus_out(&mut self, blurred_id: usize, cx: &mut WindowContext, view_id: usize) {
2523        let mut cx = ViewContext::mutable(cx, view_id);
2524        let blurred_view_handle: AnyViewHandle = if view_id == blurred_id {
2525            cx.handle().into_any()
2526        } else {
2527            let blurred_type = cx
2528                .views_metadata
2529                .get(&(cx.window_id, blurred_id))
2530                .unwrap()
2531                .type_id;
2532            AnyViewHandle::new(
2533                cx.window_id,
2534                blurred_id,
2535                blurred_type,
2536                cx.ref_counts.clone(),
2537            )
2538        };
2539        View::focus_out(self, blurred_view_handle, &mut cx);
2540    }
2541
2542    fn key_down(&mut self, event: &KeyDownEvent, cx: &mut WindowContext, view_id: usize) -> bool {
2543        let mut cx = ViewContext::mutable(cx, view_id);
2544        View::key_down(self, event, &mut cx)
2545    }
2546
2547    fn key_up(&mut self, event: &KeyUpEvent, cx: &mut WindowContext, view_id: usize) -> bool {
2548        let mut cx = ViewContext::mutable(cx, view_id);
2549        View::key_up(self, event, &mut cx)
2550    }
2551
2552    fn modifiers_changed(
2553        &mut self,
2554        event: &ModifiersChangedEvent,
2555        cx: &mut WindowContext,
2556        view_id: usize,
2557    ) -> bool {
2558        let mut cx = ViewContext::mutable(cx, view_id);
2559        View::modifiers_changed(self, event, &mut cx)
2560    }
2561
2562    fn update_keymap_context(&self, keymap: &mut KeymapContext, cx: &AppContext) {
2563        View::update_keymap_context(self, keymap, cx)
2564    }
2565
2566    fn debug_json(&self, cx: &WindowContext) -> serde_json::Value {
2567        View::debug_json(self, cx)
2568    }
2569
2570    fn text_for_range(&self, range: Range<usize>, cx: &WindowContext) -> Option<String> {
2571        View::text_for_range(self, range, cx)
2572    }
2573
2574    fn selected_text_range(&self, cx: &WindowContext) -> Option<Range<usize>> {
2575        View::selected_text_range(self, cx)
2576    }
2577
2578    fn marked_text_range(&self, cx: &WindowContext) -> Option<Range<usize>> {
2579        View::marked_text_range(self, cx)
2580    }
2581
2582    fn unmark_text(&mut self, cx: &mut WindowContext, view_id: usize) {
2583        let mut cx = ViewContext::mutable(cx, view_id);
2584        View::unmark_text(self, &mut cx)
2585    }
2586
2587    fn replace_text_in_range(
2588        &mut self,
2589        range: Option<Range<usize>>,
2590        text: &str,
2591        cx: &mut WindowContext,
2592        view_id: usize,
2593    ) {
2594        let mut cx = ViewContext::mutable(cx, view_id);
2595        View::replace_text_in_range(self, range, text, &mut cx)
2596    }
2597
2598    fn replace_and_mark_text_in_range(
2599        &mut self,
2600        range: Option<Range<usize>>,
2601        new_text: &str,
2602        new_selected_range: Option<Range<usize>>,
2603        cx: &mut WindowContext,
2604        view_id: usize,
2605    ) {
2606        let mut cx = ViewContext::mutable(cx, view_id);
2607        View::replace_and_mark_text_in_range(self, range, new_text, new_selected_range, &mut cx)
2608    }
2609}
2610
2611pub struct ModelContext<'a, T: ?Sized> {
2612    app: &'a mut AppContext,
2613    model_id: usize,
2614    model_type: PhantomData<T>,
2615    halt_stream: bool,
2616}
2617
2618impl<'a, T: Entity> ModelContext<'a, T> {
2619    fn new(app: &'a mut AppContext, model_id: usize) -> Self {
2620        Self {
2621            app,
2622            model_id,
2623            model_type: PhantomData,
2624            halt_stream: false,
2625        }
2626    }
2627
2628    pub fn background(&self) -> &Arc<executor::Background> {
2629        &self.app.background
2630    }
2631
2632    pub fn halt_stream(&mut self) {
2633        self.halt_stream = true;
2634    }
2635
2636    pub fn model_id(&self) -> usize {
2637        self.model_id
2638    }
2639
2640    pub fn add_model<S, F>(&mut self, build_model: F) -> ModelHandle<S>
2641    where
2642        S: Entity,
2643        F: FnOnce(&mut ModelContext<S>) -> S,
2644    {
2645        self.app.add_model(build_model)
2646    }
2647
2648    pub fn emit(&mut self, payload: T::Event) {
2649        self.app.pending_effects.push_back(Effect::Event {
2650            entity_id: self.model_id,
2651            payload: Box::new(payload),
2652        });
2653    }
2654
2655    pub fn notify(&mut self) {
2656        self.app.notify_model(self.model_id);
2657    }
2658
2659    pub fn subscribe<S: Entity, F>(
2660        &mut self,
2661        handle: &ModelHandle<S>,
2662        mut callback: F,
2663    ) -> Subscription
2664    where
2665        S::Event: 'static,
2666        F: 'static + FnMut(&mut T, ModelHandle<S>, &S::Event, &mut ModelContext<T>),
2667    {
2668        let subscriber = self.weak_handle();
2669        self.app
2670            .subscribe_internal(handle, move |emitter, event, cx| {
2671                if let Some(subscriber) = subscriber.upgrade(cx) {
2672                    subscriber.update(cx, |subscriber, cx| {
2673                        callback(subscriber, emitter, event, cx);
2674                    });
2675                    true
2676                } else {
2677                    false
2678                }
2679            })
2680    }
2681
2682    pub fn observe<S, F>(&mut self, handle: &ModelHandle<S>, mut callback: F) -> Subscription
2683    where
2684        S: Entity,
2685        F: 'static + FnMut(&mut T, ModelHandle<S>, &mut ModelContext<T>),
2686    {
2687        let observer = self.weak_handle();
2688        self.app.observe_internal(handle, move |observed, cx| {
2689            if let Some(observer) = observer.upgrade(cx) {
2690                observer.update(cx, |observer, cx| {
2691                    callback(observer, observed, cx);
2692                });
2693                true
2694            } else {
2695                false
2696            }
2697        })
2698    }
2699
2700    pub fn observe_global<G, F>(&mut self, mut callback: F) -> Subscription
2701    where
2702        G: Any,
2703        F: 'static + FnMut(&mut T, &mut ModelContext<T>),
2704    {
2705        let observer = self.weak_handle();
2706        self.app.observe_global::<G, _>(move |cx| {
2707            if let Some(observer) = observer.upgrade(cx) {
2708                observer.update(cx, |observer, cx| callback(observer, cx));
2709            }
2710        })
2711    }
2712
2713    pub fn observe_release<S, F>(
2714        &mut self,
2715        handle: &ModelHandle<S>,
2716        mut callback: F,
2717    ) -> Subscription
2718    where
2719        S: Entity,
2720        F: 'static + FnMut(&mut T, &S, &mut ModelContext<T>),
2721    {
2722        let observer = self.weak_handle();
2723        self.app.observe_release(handle, move |released, cx| {
2724            if let Some(observer) = observer.upgrade(cx) {
2725                observer.update(cx, |observer, cx| {
2726                    callback(observer, released, cx);
2727                });
2728            }
2729        })
2730    }
2731
2732    pub fn handle(&self) -> ModelHandle<T> {
2733        ModelHandle::new(self.model_id, &self.app.ref_counts)
2734    }
2735
2736    pub fn weak_handle(&self) -> WeakModelHandle<T> {
2737        WeakModelHandle::new(self.model_id)
2738    }
2739
2740    pub fn spawn<F, Fut, S>(&mut self, f: F) -> Task<S>
2741    where
2742        F: FnOnce(ModelHandle<T>, AsyncAppContext) -> Fut,
2743        Fut: 'static + Future<Output = S>,
2744        S: 'static,
2745    {
2746        let handle = self.handle();
2747        self.app.spawn(|cx| f(handle, cx))
2748    }
2749
2750    pub fn spawn_weak<F, Fut, S>(&mut self, f: F) -> Task<S>
2751    where
2752        F: FnOnce(WeakModelHandle<T>, AsyncAppContext) -> Fut,
2753        Fut: 'static + Future<Output = S>,
2754        S: 'static,
2755    {
2756        let handle = self.weak_handle();
2757        self.app.spawn(|cx| f(handle, cx))
2758    }
2759}
2760
2761impl<M> AsRef<AppContext> for ModelContext<'_, M> {
2762    fn as_ref(&self) -> &AppContext {
2763        &self.app
2764    }
2765}
2766
2767impl<M> AsMut<AppContext> for ModelContext<'_, M> {
2768    fn as_mut(&mut self) -> &mut AppContext {
2769        self.app
2770    }
2771}
2772
2773impl<M> BorrowAppContext for ModelContext<'_, M> {
2774    fn read_with<T, F: FnOnce(&AppContext) -> T>(&self, f: F) -> T {
2775        self.app.read_with(f)
2776    }
2777
2778    fn update<T, F: FnOnce(&mut AppContext) -> T>(&mut self, f: F) -> T {
2779        self.app.update(f)
2780    }
2781}
2782
2783impl<M> Deref for ModelContext<'_, M> {
2784    type Target = AppContext;
2785
2786    fn deref(&self) -> &Self::Target {
2787        self.app
2788    }
2789}
2790
2791impl<M> DerefMut for ModelContext<'_, M> {
2792    fn deref_mut(&mut self) -> &mut Self::Target {
2793        &mut self.app
2794    }
2795}
2796
2797pub struct ViewContext<'a, 'b, T: ?Sized> {
2798    window_context: Reference<'b, WindowContext<'a>>,
2799    view_id: usize,
2800    view_type: PhantomData<T>,
2801}
2802
2803impl<'a, 'b, T: View> Deref for ViewContext<'a, 'b, T> {
2804    type Target = WindowContext<'a>;
2805
2806    fn deref(&self) -> &Self::Target {
2807        &self.window_context
2808    }
2809}
2810
2811impl<T: View> DerefMut for ViewContext<'_, '_, T> {
2812    fn deref_mut(&mut self) -> &mut Self::Target {
2813        &mut self.window_context
2814    }
2815}
2816
2817impl<'a, 'b, V: View> ViewContext<'a, 'b, V> {
2818    pub(crate) fn mutable(window_context: &'b mut WindowContext<'a>, view_id: usize) -> Self {
2819        Self {
2820            window_context: Reference::Mutable(window_context),
2821            view_id,
2822            view_type: PhantomData,
2823        }
2824    }
2825
2826    pub(crate) fn immutable(window_context: &'b WindowContext<'a>, view_id: usize) -> Self {
2827        Self {
2828            window_context: Reference::Immutable(window_context),
2829            view_id,
2830            view_type: PhantomData,
2831        }
2832    }
2833
2834    pub fn window_context(&mut self) -> &mut WindowContext<'a> {
2835        &mut self.window_context
2836    }
2837
2838    pub fn handle(&self) -> ViewHandle<V> {
2839        ViewHandle::new(
2840            self.window_id,
2841            self.view_id,
2842            &self.window_context.ref_counts,
2843        )
2844    }
2845
2846    pub fn weak_handle(&self) -> WeakViewHandle<V> {
2847        WeakViewHandle::new(self.window_id, self.view_id)
2848    }
2849
2850    pub fn window_id(&self) -> usize {
2851        self.window_id
2852    }
2853
2854    pub fn view_id(&self) -> usize {
2855        self.view_id
2856    }
2857
2858    pub fn foreground(&self) -> &Rc<executor::Foreground> {
2859        self.window_context.foreground()
2860    }
2861
2862    pub fn background_executor(&self) -> &Arc<executor::Background> {
2863        &self.window_context.background
2864    }
2865
2866    pub fn platform(&self) -> &Arc<dyn Platform> {
2867        self.window_context.platform()
2868    }
2869
2870    pub fn prompt_for_paths(
2871        &self,
2872        options: PathPromptOptions,
2873    ) -> oneshot::Receiver<Option<Vec<PathBuf>>> {
2874        self.window_context.prompt_for_paths(options)
2875    }
2876
2877    pub fn prompt_for_new_path(&self, directory: &Path) -> oneshot::Receiver<Option<PathBuf>> {
2878        self.window_context.prompt_for_new_path(directory)
2879    }
2880
2881    pub fn reveal_path(&self, path: &Path) {
2882        self.window_context.reveal_path(path)
2883    }
2884
2885    pub fn focus(&mut self, handle: &AnyViewHandle) {
2886        self.window_context
2887            .focus(handle.window_id, Some(handle.view_id));
2888    }
2889
2890    pub fn focus_self(&mut self) {
2891        let window_id = self.window_id;
2892        let view_id = self.view_id;
2893        self.window_context.focus(window_id, Some(view_id));
2894    }
2895
2896    pub fn is_self_focused(&self) -> bool {
2897        self.window.focused_view_id == Some(self.view_id)
2898    }
2899
2900    pub fn focus_parent(&mut self) {
2901        let window_id = self.window_id;
2902        let view_id = self.view_id;
2903        self.pending_effects
2904            .push_back(Effect::Focus(FocusEffect::ViewParent {
2905                window_id,
2906                view_id,
2907                is_forced: false,
2908            }));
2909    }
2910
2911    pub fn blur(&mut self) {
2912        let window_id = self.window_id;
2913        self.window_context.focus(window_id, None);
2914    }
2915
2916    pub fn on_window_should_close<F>(&mut self, mut callback: F)
2917    where
2918        F: 'static + FnMut(&mut V, &mut ViewContext<V>) -> bool,
2919    {
2920        let window_id = self.window_id;
2921        let view = self.weak_handle();
2922        self.pending_effects
2923            .push_back(Effect::WindowShouldCloseSubscription {
2924                window_id,
2925                callback: Box::new(move |cx| {
2926                    cx.update_window(window_id, |cx| {
2927                        if let Some(view) = view.upgrade(cx) {
2928                            view.update(cx, |view, cx| callback(view, cx))
2929                        } else {
2930                            true
2931                        }
2932                    })
2933                    .unwrap_or(true)
2934                }),
2935            });
2936    }
2937
2938    pub fn subscribe<E, H, F>(&mut self, handle: &H, mut callback: F) -> Subscription
2939    where
2940        E: Entity,
2941        E::Event: 'static,
2942        H: Handle<E>,
2943        F: 'static + FnMut(&mut V, H, &E::Event, &mut ViewContext<V>),
2944    {
2945        let subscriber = self.weak_handle();
2946        self.window_context
2947            .subscribe_internal(handle, move |emitter, event, cx| {
2948                if let Some(subscriber) = subscriber.upgrade(cx) {
2949                    subscriber.update(cx, |subscriber, cx| {
2950                        callback(subscriber, emitter, event, cx);
2951                    });
2952                    true
2953                } else {
2954                    false
2955                }
2956            })
2957    }
2958
2959    pub fn observe<E, F, H>(&mut self, handle: &H, mut callback: F) -> Subscription
2960    where
2961        E: Entity,
2962        H: Handle<E>,
2963        F: 'static + FnMut(&mut V, H, &mut ViewContext<V>),
2964    {
2965        let window_id = self.window_id;
2966        let observer = self.weak_handle();
2967        self.window_context
2968            .observe_internal(handle, move |observed, cx| {
2969                cx.update_window(window_id, |cx| {
2970                    if let Some(observer) = observer.upgrade(cx) {
2971                        observer.update(cx, |observer, cx| {
2972                            callback(observer, observed, cx);
2973                        });
2974                        true
2975                    } else {
2976                        false
2977                    }
2978                })
2979                .unwrap_or(false)
2980            })
2981    }
2982
2983    pub fn observe_global<G, F>(&mut self, mut callback: F) -> Subscription
2984    where
2985        G: Any,
2986        F: 'static + FnMut(&mut V, &mut ViewContext<V>),
2987    {
2988        let window_id = self.window_id;
2989        let observer = self.weak_handle();
2990        self.window_context.observe_global::<G, _>(move |cx| {
2991            cx.update_window(window_id, |cx| {
2992                if let Some(observer) = observer.upgrade(cx) {
2993                    observer.update(cx, |observer, cx| callback(observer, cx));
2994                }
2995            });
2996        })
2997    }
2998
2999    pub fn observe_focus<F, W>(&mut self, handle: &ViewHandle<W>, mut callback: F) -> Subscription
3000    where
3001        F: 'static + FnMut(&mut V, ViewHandle<W>, bool, &mut ViewContext<V>),
3002        W: View,
3003    {
3004        let observer = self.weak_handle();
3005        self.window_context
3006            .observe_focus(handle, move |observed, focused, cx| {
3007                if let Some(observer) = observer.upgrade(cx) {
3008                    observer.update(cx, |observer, cx| {
3009                        callback(observer, observed, focused, cx);
3010                    });
3011                    true
3012                } else {
3013                    false
3014                }
3015            })
3016    }
3017
3018    pub fn observe_release<E, F, H>(&mut self, handle: &H, mut callback: F) -> Subscription
3019    where
3020        E: Entity,
3021        H: Handle<E>,
3022        F: 'static + FnMut(&mut V, &E, &mut ViewContext<V>),
3023    {
3024        let window_id = self.window_id;
3025        let observer = self.weak_handle();
3026        self.window_context
3027            .observe_release(handle, move |released, cx| {
3028                cx.update_window(window_id, |cx| {
3029                    if let Some(observer) = observer.upgrade(cx) {
3030                        observer.update(cx, |observer, cx| {
3031                            callback(observer, released, cx);
3032                        });
3033                    }
3034                });
3035            })
3036    }
3037
3038    pub fn observe_actions<F>(&mut self, mut callback: F) -> Subscription
3039    where
3040        F: 'static + FnMut(&mut V, TypeId, &mut ViewContext<V>),
3041    {
3042        let window_id = self.window_id;
3043        let observer = self.weak_handle();
3044        self.window_context.observe_actions(move |action_id, cx| {
3045            cx.update_window(window_id, |cx| {
3046                if let Some(observer) = observer.upgrade(cx) {
3047                    observer.update(cx, |observer, cx| {
3048                        callback(observer, action_id, cx);
3049                    });
3050                }
3051            });
3052        })
3053    }
3054
3055    pub fn observe_window_activation<F>(&mut self, mut callback: F) -> Subscription
3056    where
3057        F: 'static + FnMut(&mut V, bool, &mut ViewContext<V>),
3058    {
3059        let observer = self.weak_handle();
3060        self.window_context
3061            .observe_window_activation(move |active, cx| {
3062                if let Some(observer) = observer.upgrade(cx) {
3063                    observer.update(cx, |observer, cx| {
3064                        callback(observer, active, cx);
3065                    });
3066                    true
3067                } else {
3068                    false
3069                }
3070            })
3071    }
3072
3073    pub fn observe_fullscreen<F>(&mut self, mut callback: F) -> Subscription
3074    where
3075        F: 'static + FnMut(&mut V, bool, &mut ViewContext<V>),
3076    {
3077        let observer = self.weak_handle();
3078        self.window_context.observe_fullscreen(move |active, cx| {
3079            if let Some(observer) = observer.upgrade(cx) {
3080                observer.update(cx, |observer, cx| {
3081                    callback(observer, active, cx);
3082                });
3083                true
3084            } else {
3085                false
3086            }
3087        })
3088    }
3089
3090    pub fn observe_keystrokes<F>(&mut self, mut callback: F) -> Subscription
3091    where
3092        F: 'static
3093            + FnMut(
3094                &mut V,
3095                &Keystroke,
3096                Option<&Box<dyn Action>>,
3097                &MatchResult,
3098                &mut ViewContext<V>,
3099            ) -> bool,
3100    {
3101        let observer = self.weak_handle();
3102        self.window_context
3103            .observe_keystrokes(move |keystroke, result, handled_by, cx| {
3104                if let Some(observer) = observer.upgrade(cx) {
3105                    observer.update(cx, |observer, cx| {
3106                        callback(observer, keystroke, handled_by, result, cx);
3107                    });
3108                    true
3109                } else {
3110                    false
3111                }
3112            })
3113    }
3114
3115    pub fn observe_window_bounds<F>(&mut self, mut callback: F) -> Subscription
3116    where
3117        F: 'static + FnMut(&mut V, WindowBounds, Uuid, &mut ViewContext<V>),
3118    {
3119        let observer = self.weak_handle();
3120        self.window_context
3121            .observe_window_bounds(move |bounds, display, cx| {
3122                if let Some(observer) = observer.upgrade(cx) {
3123                    observer.update(cx, |observer, cx| {
3124                        callback(observer, bounds, display, cx);
3125                    });
3126                    true
3127                } else {
3128                    false
3129                }
3130            })
3131    }
3132
3133    pub fn observe_active_labeled_tasks<F>(&mut self, mut callback: F) -> Subscription
3134    where
3135        F: 'static + FnMut(&mut V, &mut ViewContext<V>),
3136    {
3137        let window_id = self.window_id;
3138        let observer = self.weak_handle();
3139        self.window_context.observe_active_labeled_tasks(move |cx| {
3140            cx.update_window(window_id, |cx| {
3141                if let Some(observer) = observer.upgrade(cx) {
3142                    observer.update(cx, |observer, cx| {
3143                        callback(observer, cx);
3144                    });
3145                    true
3146                } else {
3147                    false
3148                }
3149            })
3150            .unwrap_or(false)
3151        })
3152    }
3153
3154    pub fn emit(&mut self, payload: V::Event) {
3155        self.window_context
3156            .pending_effects
3157            .push_back(Effect::Event {
3158                entity_id: self.view_id,
3159                payload: Box::new(payload),
3160            });
3161    }
3162
3163    pub fn notify(&mut self) {
3164        let window_id = self.window_id;
3165        let view_id = self.view_id;
3166        self.window_context.notify_view(window_id, view_id);
3167    }
3168
3169    pub fn defer(&mut self, callback: impl 'static + FnOnce(&mut V, &mut ViewContext<V>)) {
3170        let handle = self.handle();
3171        self.window_context
3172            .defer(move |cx| handle.update(cx, |view, cx| callback(view, cx)))
3173    }
3174
3175    pub fn after_window_update(
3176        &mut self,
3177        callback: impl 'static + FnOnce(&mut V, &mut ViewContext<V>),
3178    ) {
3179        let window_id = self.window_id;
3180        let handle = self.handle();
3181        self.window_context.after_window_update(move |cx| {
3182            cx.update_window(window_id, |cx| {
3183                handle.update(cx, |view, cx| {
3184                    callback(view, cx);
3185                })
3186            });
3187        })
3188    }
3189
3190    pub fn propagate_action(&mut self) {
3191        self.window_context.halt_action_dispatch = false;
3192    }
3193
3194    pub fn spawn_labeled<F, Fut, S>(&mut self, task_label: &'static str, f: F) -> Task<S>
3195    where
3196        F: FnOnce(WeakViewHandle<V>, AsyncAppContext) -> Fut,
3197        Fut: 'static + Future<Output = S>,
3198        S: 'static,
3199    {
3200        let handle = self.weak_handle();
3201        self.window_context
3202            .spawn_labeled(task_label, |cx| f(handle, cx))
3203    }
3204
3205    pub fn spawn<F, Fut, S>(&mut self, f: F) -> Task<S>
3206    where
3207        F: FnOnce(WeakViewHandle<V>, AsyncAppContext) -> Fut,
3208        Fut: 'static + Future<Output = S>,
3209        S: 'static,
3210    {
3211        let handle = self.weak_handle();
3212        self.window_context.spawn(|cx| f(handle, cx))
3213    }
3214
3215    pub fn mouse_state<Tag: 'static>(&self, region_id: usize) -> MouseState {
3216        let region_id = MouseRegionId::new::<Tag>(self.view_id, region_id);
3217        MouseState {
3218            hovered: self.window.hovered_region_ids.contains(&region_id),
3219            clicked: self
3220                .window
3221                .clicked_region_ids
3222                .get(&region_id)
3223                .and_then(|_| self.window.clicked_button),
3224            accessed_hovered: false,
3225            accessed_clicked: false,
3226        }
3227    }
3228
3229    pub fn element_state<Tag: 'static, T: 'static>(
3230        &mut self,
3231        element_id: usize,
3232        initial: T,
3233    ) -> ElementStateHandle<T> {
3234        let id = ElementStateId {
3235            view_id: self.view_id(),
3236            element_id,
3237            tag: TypeId::of::<Tag>(),
3238        };
3239        self.element_states
3240            .entry(id)
3241            .or_insert_with(|| Box::new(initial));
3242        ElementStateHandle::new(id, self.frame_count, &self.ref_counts)
3243    }
3244
3245    pub fn default_element_state<Tag: 'static, T: 'static + Default>(
3246        &mut self,
3247        element_id: usize,
3248    ) -> ElementStateHandle<T> {
3249        self.element_state::<Tag, T>(element_id, T::default())
3250    }
3251}
3252
3253impl<V> BorrowAppContext for ViewContext<'_, '_, V> {
3254    fn read_with<T, F: FnOnce(&AppContext) -> T>(&self, f: F) -> T {
3255        BorrowAppContext::read_with(&*self.window_context, f)
3256    }
3257
3258    fn update<T, F: FnOnce(&mut AppContext) -> T>(&mut self, f: F) -> T {
3259        BorrowAppContext::update(&mut *self.window_context, f)
3260    }
3261}
3262
3263impl<V> BorrowWindowContext for ViewContext<'_, '_, V> {
3264    fn read_with<T, F: FnOnce(&WindowContext) -> T>(&self, window_id: usize, f: F) -> T {
3265        BorrowWindowContext::read_with(&*self.window_context, window_id, f)
3266    }
3267
3268    fn update<T, F: FnOnce(&mut WindowContext) -> T>(&mut self, window_id: usize, f: F) -> T {
3269        BorrowWindowContext::update(&mut *self.window_context, window_id, f)
3270    }
3271}
3272
3273pub struct LayoutContext<'a, 'b, 'c, V: View> {
3274    view_context: &'c mut ViewContext<'a, 'b, V>,
3275    new_parents: &'c mut HashMap<usize, usize>,
3276    views_to_notify_if_ancestors_change: &'c mut HashMap<usize, SmallVec<[usize; 2]>>,
3277    pub refreshing: bool,
3278}
3279
3280impl<'a, 'b, 'c, V: View> LayoutContext<'a, 'b, 'c, V> {
3281    pub fn new(
3282        view_context: &'c mut ViewContext<'a, 'b, V>,
3283        new_parents: &'c mut HashMap<usize, usize>,
3284        views_to_notify_if_ancestors_change: &'c mut HashMap<usize, SmallVec<[usize; 2]>>,
3285        refreshing: bool,
3286    ) -> Self {
3287        Self {
3288            view_context,
3289            new_parents,
3290            views_to_notify_if_ancestors_change,
3291            refreshing,
3292        }
3293    }
3294
3295    pub fn view_context(&mut self) -> &mut ViewContext<'a, 'b, V> {
3296        self.view_context
3297    }
3298
3299    /// Return keystrokes that would dispatch the given action on the given view.
3300    pub(crate) fn keystrokes_for_action(
3301        &mut self,
3302        view_id: usize,
3303        action: &dyn Action,
3304    ) -> Option<SmallVec<[Keystroke; 2]>> {
3305        self.notify_if_view_ancestors_change(view_id);
3306
3307        let window_id = self.window_id;
3308        let mut contexts = Vec::new();
3309        let mut handler_depth = None;
3310        for (i, view_id) in self.ancestors(view_id).enumerate() {
3311            if let Some(view_metadata) = self.views_metadata.get(&(window_id, view_id)) {
3312                if let Some(actions) = self.actions.get(&view_metadata.type_id) {
3313                    if actions.contains_key(&action.as_any().type_id()) {
3314                        handler_depth = Some(i);
3315                    }
3316                }
3317                contexts.push(view_metadata.keymap_context.clone());
3318            }
3319        }
3320
3321        if self.global_actions.contains_key(&action.as_any().type_id()) {
3322            handler_depth = Some(contexts.len())
3323        }
3324
3325        self.keystroke_matcher
3326            .bindings_for_action_type(action.as_any().type_id())
3327            .find_map(|b| {
3328                handler_depth
3329                    .map(|highest_handler| {
3330                        if (0..=highest_handler).any(|depth| b.match_context(&contexts[depth..])) {
3331                            Some(b.keystrokes().into())
3332                        } else {
3333                            None
3334                        }
3335                    })
3336                    .flatten()
3337            })
3338    }
3339
3340    fn notify_if_view_ancestors_change(&mut self, view_id: usize) {
3341        let self_view_id = self.view_id;
3342        self.views_to_notify_if_ancestors_change
3343            .entry(view_id)
3344            .or_default()
3345            .push(self_view_id);
3346    }
3347}
3348
3349impl<'a, 'b, 'c, V: View> Deref for LayoutContext<'a, 'b, 'c, V> {
3350    type Target = ViewContext<'a, 'b, V>;
3351
3352    fn deref(&self) -> &Self::Target {
3353        &self.view_context
3354    }
3355}
3356
3357impl<V: View> DerefMut for LayoutContext<'_, '_, '_, V> {
3358    fn deref_mut(&mut self) -> &mut Self::Target {
3359        &mut self.view_context
3360    }
3361}
3362
3363impl<V: View> BorrowAppContext for LayoutContext<'_, '_, '_, V> {
3364    fn read_with<T, F: FnOnce(&AppContext) -> T>(&self, f: F) -> T {
3365        BorrowAppContext::read_with(&*self.view_context, f)
3366    }
3367
3368    fn update<T, F: FnOnce(&mut AppContext) -> T>(&mut self, f: F) -> T {
3369        BorrowAppContext::update(&mut *self.view_context, f)
3370    }
3371}
3372
3373impl<V: View> BorrowWindowContext for LayoutContext<'_, '_, '_, V> {
3374    fn read_with<T, F: FnOnce(&WindowContext) -> T>(&self, window_id: usize, f: F) -> T {
3375        BorrowWindowContext::read_with(&*self.view_context, window_id, f)
3376    }
3377
3378    fn update<T, F: FnOnce(&mut WindowContext) -> T>(&mut self, window_id: usize, f: F) -> T {
3379        BorrowWindowContext::update(&mut *self.view_context, window_id, f)
3380    }
3381}
3382
3383pub struct EventContext<'a, 'b, 'c, V: View> {
3384    view_context: &'c mut ViewContext<'a, 'b, V>,
3385    pub(crate) handled: bool,
3386}
3387
3388impl<'a, 'b, 'c, V: View> EventContext<'a, 'b, 'c, V> {
3389    pub(crate) fn new(view_context: &'c mut ViewContext<'a, 'b, V>) -> Self {
3390        EventContext {
3391            view_context,
3392            handled: true,
3393        }
3394    }
3395
3396    pub fn propagate_event(&mut self) {
3397        self.handled = false;
3398    }
3399}
3400
3401impl<'a, 'b, 'c, V: View> Deref for EventContext<'a, 'b, 'c, V> {
3402    type Target = ViewContext<'a, 'b, V>;
3403
3404    fn deref(&self) -> &Self::Target {
3405        &self.view_context
3406    }
3407}
3408
3409impl<V: View> DerefMut for EventContext<'_, '_, '_, V> {
3410    fn deref_mut(&mut self) -> &mut Self::Target {
3411        &mut self.view_context
3412    }
3413}
3414
3415impl<V: View> BorrowAppContext for EventContext<'_, '_, '_, V> {
3416    fn read_with<T, F: FnOnce(&AppContext) -> T>(&self, f: F) -> T {
3417        BorrowAppContext::read_with(&*self.view_context, f)
3418    }
3419
3420    fn update<T, F: FnOnce(&mut AppContext) -> T>(&mut self, f: F) -> T {
3421        BorrowAppContext::update(&mut *self.view_context, f)
3422    }
3423}
3424
3425impl<V: View> BorrowWindowContext for EventContext<'_, '_, '_, V> {
3426    fn read_with<T, F: FnOnce(&WindowContext) -> T>(&self, window_id: usize, f: F) -> T {
3427        BorrowWindowContext::read_with(&*self.view_context, window_id, f)
3428    }
3429
3430    fn update<T, F: FnOnce(&mut WindowContext) -> T>(&mut self, window_id: usize, f: F) -> T {
3431        BorrowWindowContext::update(&mut *self.view_context, window_id, f)
3432    }
3433}
3434
3435pub(crate) enum Reference<'a, T> {
3436    Immutable(&'a T),
3437    Mutable(&'a mut T),
3438}
3439
3440impl<'a, T> Deref for Reference<'a, T> {
3441    type Target = T;
3442
3443    fn deref(&self) -> &Self::Target {
3444        match self {
3445            Reference::Immutable(target) => target,
3446            Reference::Mutable(target) => target,
3447        }
3448    }
3449}
3450
3451impl<'a, T> DerefMut for Reference<'a, T> {
3452    fn deref_mut(&mut self) -> &mut Self::Target {
3453        match self {
3454            Reference::Immutable(_) => {
3455                panic!("cannot mutably deref an immutable reference. this is a bug in GPUI.");
3456            }
3457            Reference::Mutable(target) => target,
3458        }
3459    }
3460}
3461
3462#[derive(Debug, Clone, Default)]
3463pub struct MouseState {
3464    pub(crate) hovered: bool,
3465    pub(crate) clicked: Option<MouseButton>,
3466    pub(crate) accessed_hovered: bool,
3467    pub(crate) accessed_clicked: bool,
3468}
3469
3470impl MouseState {
3471    pub fn hovered(&mut self) -> bool {
3472        self.accessed_hovered = true;
3473        self.hovered
3474    }
3475
3476    pub fn clicked(&mut self) -> Option<MouseButton> {
3477        self.accessed_clicked = true;
3478        self.clicked
3479    }
3480
3481    pub fn accessed_hovered(&self) -> bool {
3482        self.accessed_hovered
3483    }
3484
3485    pub fn accessed_clicked(&self) -> bool {
3486        self.accessed_clicked
3487    }
3488}
3489
3490pub trait Handle<T> {
3491    type Weak: 'static;
3492    fn id(&self) -> usize;
3493    fn location(&self) -> EntityLocation;
3494    fn downgrade(&self) -> Self::Weak;
3495    fn upgrade_from(weak: &Self::Weak, cx: &AppContext) -> Option<Self>
3496    where
3497        Self: Sized;
3498}
3499
3500pub trait WeakHandle {
3501    fn id(&self) -> usize;
3502}
3503
3504#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash)]
3505pub enum EntityLocation {
3506    Model(usize),
3507    View(usize, usize),
3508}
3509
3510pub struct ModelHandle<T: Entity> {
3511    any_handle: AnyModelHandle,
3512    model_type: PhantomData<T>,
3513}
3514
3515impl<T: Entity> Deref for ModelHandle<T> {
3516    type Target = AnyModelHandle;
3517
3518    fn deref(&self) -> &Self::Target {
3519        &self.any_handle
3520    }
3521}
3522
3523impl<T: Entity> ModelHandle<T> {
3524    fn new(model_id: usize, ref_counts: &Arc<Mutex<RefCounts>>) -> Self {
3525        Self {
3526            any_handle: AnyModelHandle::new(model_id, TypeId::of::<T>(), ref_counts.clone()),
3527            model_type: PhantomData,
3528        }
3529    }
3530
3531    pub fn downgrade(&self) -> WeakModelHandle<T> {
3532        WeakModelHandle::new(self.model_id)
3533    }
3534
3535    pub fn id(&self) -> usize {
3536        self.model_id
3537    }
3538
3539    pub fn read<'a>(&self, cx: &'a AppContext) -> &'a T {
3540        cx.read_model(self)
3541    }
3542
3543    pub fn read_with<C, F, S>(&self, cx: &C, read: F) -> S
3544    where
3545        C: BorrowAppContext,
3546        F: FnOnce(&T, &AppContext) -> S,
3547    {
3548        cx.read_with(|cx| read(self.read(cx), cx))
3549    }
3550
3551    pub fn update<C, F, S>(&self, cx: &mut C, update: F) -> S
3552    where
3553        C: BorrowAppContext,
3554        F: FnOnce(&mut T, &mut ModelContext<T>) -> S,
3555    {
3556        let mut update = Some(update);
3557        cx.update(|cx| {
3558            cx.update_model(self, &mut |model, cx| {
3559                let update = update.take().unwrap();
3560                update(model, cx)
3561            })
3562        })
3563    }
3564}
3565
3566impl<T: Entity> Clone for ModelHandle<T> {
3567    fn clone(&self) -> Self {
3568        Self::new(self.model_id, &self.ref_counts)
3569    }
3570}
3571
3572impl<T: Entity> PartialEq for ModelHandle<T> {
3573    fn eq(&self, other: &Self) -> bool {
3574        self.model_id == other.model_id
3575    }
3576}
3577
3578impl<T: Entity> Eq for ModelHandle<T> {}
3579
3580impl<T: Entity> PartialEq<WeakModelHandle<T>> for ModelHandle<T> {
3581    fn eq(&self, other: &WeakModelHandle<T>) -> bool {
3582        self.model_id == other.model_id
3583    }
3584}
3585
3586impl<T: Entity> Hash for ModelHandle<T> {
3587    fn hash<H: Hasher>(&self, state: &mut H) {
3588        self.model_id.hash(state);
3589    }
3590}
3591
3592impl<T: Entity> std::borrow::Borrow<usize> for ModelHandle<T> {
3593    fn borrow(&self) -> &usize {
3594        &self.model_id
3595    }
3596}
3597
3598impl<T: Entity> Debug for ModelHandle<T> {
3599    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
3600        f.debug_tuple(&format!("ModelHandle<{}>", type_name::<T>()))
3601            .field(&self.model_id)
3602            .finish()
3603    }
3604}
3605
3606unsafe impl<T: Entity> Send for ModelHandle<T> {}
3607unsafe impl<T: Entity> Sync for ModelHandle<T> {}
3608
3609impl<T: Entity> Handle<T> for ModelHandle<T> {
3610    type Weak = WeakModelHandle<T>;
3611
3612    fn id(&self) -> usize {
3613        self.model_id
3614    }
3615
3616    fn location(&self) -> EntityLocation {
3617        EntityLocation::Model(self.model_id)
3618    }
3619
3620    fn downgrade(&self) -> Self::Weak {
3621        self.downgrade()
3622    }
3623
3624    fn upgrade_from(weak: &Self::Weak, cx: &AppContext) -> Option<Self>
3625    where
3626        Self: Sized,
3627    {
3628        weak.upgrade(cx)
3629    }
3630}
3631
3632pub struct WeakModelHandle<T> {
3633    any_handle: AnyWeakModelHandle,
3634    model_type: PhantomData<T>,
3635}
3636
3637impl<T> WeakModelHandle<T> {
3638    pub fn into_any(self) -> AnyWeakModelHandle {
3639        self.any_handle
3640    }
3641}
3642
3643impl<T> Deref for WeakModelHandle<T> {
3644    type Target = AnyWeakModelHandle;
3645
3646    fn deref(&self) -> &Self::Target {
3647        &self.any_handle
3648    }
3649}
3650
3651impl<T> WeakHandle for WeakModelHandle<T> {
3652    fn id(&self) -> usize {
3653        self.model_id
3654    }
3655}
3656
3657unsafe impl<T> Send for WeakModelHandle<T> {}
3658unsafe impl<T> Sync for WeakModelHandle<T> {}
3659
3660impl<T: Entity> WeakModelHandle<T> {
3661    fn new(model_id: usize) -> Self {
3662        Self {
3663            any_handle: AnyWeakModelHandle {
3664                model_id,
3665                model_type: TypeId::of::<T>(),
3666            },
3667            model_type: PhantomData,
3668        }
3669    }
3670
3671    pub fn id(&self) -> usize {
3672        self.model_id
3673    }
3674
3675    pub fn is_upgradable(&self, cx: &impl BorrowAppContext) -> bool {
3676        cx.read_with(|cx| cx.model_handle_is_upgradable(self))
3677    }
3678
3679    pub fn upgrade(&self, cx: &impl BorrowAppContext) -> Option<ModelHandle<T>> {
3680        cx.read_with(|cx| cx.upgrade_model_handle(self))
3681    }
3682}
3683
3684impl<T> Hash for WeakModelHandle<T> {
3685    fn hash<H: Hasher>(&self, state: &mut H) {
3686        self.model_id.hash(state)
3687    }
3688}
3689
3690impl<T> PartialEq for WeakModelHandle<T> {
3691    fn eq(&self, other: &Self) -> bool {
3692        self.model_id == other.model_id
3693    }
3694}
3695
3696impl<T> Eq for WeakModelHandle<T> {}
3697
3698impl<T: Entity> PartialEq<ModelHandle<T>> for WeakModelHandle<T> {
3699    fn eq(&self, other: &ModelHandle<T>) -> bool {
3700        self.model_id == other.model_id
3701    }
3702}
3703
3704impl<T> Clone for WeakModelHandle<T> {
3705    fn clone(&self) -> Self {
3706        Self {
3707            any_handle: self.any_handle.clone(),
3708            model_type: PhantomData,
3709        }
3710    }
3711}
3712
3713impl<T> Copy for WeakModelHandle<T> {}
3714
3715#[repr(transparent)]
3716pub struct ViewHandle<T> {
3717    any_handle: AnyViewHandle,
3718    view_type: PhantomData<T>,
3719}
3720
3721impl<T> Deref for ViewHandle<T> {
3722    type Target = AnyViewHandle;
3723
3724    fn deref(&self) -> &Self::Target {
3725        &self.any_handle
3726    }
3727}
3728
3729impl<T: View> ViewHandle<T> {
3730    fn new(window_id: usize, view_id: usize, ref_counts: &Arc<Mutex<RefCounts>>) -> Self {
3731        Self {
3732            any_handle: AnyViewHandle::new(
3733                window_id,
3734                view_id,
3735                TypeId::of::<T>(),
3736                ref_counts.clone(),
3737            ),
3738            view_type: PhantomData,
3739        }
3740    }
3741
3742    pub fn downgrade(&self) -> WeakViewHandle<T> {
3743        WeakViewHandle::new(self.window_id, self.view_id)
3744    }
3745
3746    pub fn into_any(self) -> AnyViewHandle {
3747        self.any_handle
3748    }
3749
3750    pub fn window_id(&self) -> usize {
3751        self.window_id
3752    }
3753
3754    pub fn id(&self) -> usize {
3755        self.view_id
3756    }
3757
3758    pub fn read<'a>(&self, cx: &'a AppContext) -> &'a T {
3759        cx.read_view(self)
3760    }
3761
3762    pub fn read_with<C, F, S>(&self, cx: &C, read: F) -> S
3763    where
3764        C: BorrowWindowContext,
3765        F: FnOnce(&T, &ViewContext<T>) -> S,
3766    {
3767        cx.read_with(self.window_id, |cx| {
3768            let cx = ViewContext::immutable(cx, self.view_id);
3769            read(cx.read_view(self), &cx)
3770        })
3771    }
3772
3773    pub fn update<C, F, S>(&self, cx: &mut C, update: F) -> S
3774    where
3775        C: BorrowWindowContext,
3776        F: FnOnce(&mut T, &mut ViewContext<T>) -> S,
3777    {
3778        let mut update = Some(update);
3779
3780        cx.update(self.window_id, |cx| {
3781            cx.update_view(self, &mut |view, cx| {
3782                let update = update.take().unwrap();
3783                update(view, cx)
3784            })
3785        })
3786    }
3787
3788    pub fn is_focused(&self, cx: &WindowContext) -> bool {
3789        cx.focused_view_id() == Some(self.view_id)
3790    }
3791}
3792
3793impl<T: View> Clone for ViewHandle<T> {
3794    fn clone(&self) -> Self {
3795        ViewHandle::new(self.window_id, self.view_id, &self.ref_counts)
3796    }
3797}
3798
3799impl<T> PartialEq for ViewHandle<T> {
3800    fn eq(&self, other: &Self) -> bool {
3801        self.window_id == other.window_id && self.view_id == other.view_id
3802    }
3803}
3804
3805impl<T> PartialEq<WeakViewHandle<T>> for ViewHandle<T> {
3806    fn eq(&self, other: &WeakViewHandle<T>) -> bool {
3807        self.window_id == other.window_id && self.view_id == other.view_id
3808    }
3809}
3810
3811impl<T> PartialEq<ViewHandle<T>> for WeakViewHandle<T> {
3812    fn eq(&self, other: &ViewHandle<T>) -> bool {
3813        self.window_id == other.window_id && self.view_id == other.view_id
3814    }
3815}
3816
3817impl<T> Eq for ViewHandle<T> {}
3818
3819impl<T> Hash for ViewHandle<T> {
3820    fn hash<H: Hasher>(&self, state: &mut H) {
3821        self.window_id.hash(state);
3822        self.view_id.hash(state);
3823    }
3824}
3825
3826impl<T> Debug for ViewHandle<T> {
3827    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
3828        f.debug_struct(&format!("ViewHandle<{}>", type_name::<T>()))
3829            .field("window_id", &self.window_id)
3830            .field("view_id", &self.view_id)
3831            .finish()
3832    }
3833}
3834
3835impl<T: View> Handle<T> for ViewHandle<T> {
3836    type Weak = WeakViewHandle<T>;
3837
3838    fn id(&self) -> usize {
3839        self.view_id
3840    }
3841
3842    fn location(&self) -> EntityLocation {
3843        EntityLocation::View(self.window_id, self.view_id)
3844    }
3845
3846    fn downgrade(&self) -> Self::Weak {
3847        self.downgrade()
3848    }
3849
3850    fn upgrade_from(weak: &Self::Weak, cx: &AppContext) -> Option<Self>
3851    where
3852        Self: Sized,
3853    {
3854        weak.upgrade(cx)
3855    }
3856}
3857
3858pub struct AnyViewHandle {
3859    window_id: usize,
3860    view_id: usize,
3861    view_type: TypeId,
3862    ref_counts: Arc<Mutex<RefCounts>>,
3863
3864    #[cfg(any(test, feature = "test-support"))]
3865    handle_id: usize,
3866}
3867
3868impl AnyViewHandle {
3869    fn new(
3870        window_id: usize,
3871        view_id: usize,
3872        view_type: TypeId,
3873        ref_counts: Arc<Mutex<RefCounts>>,
3874    ) -> Self {
3875        ref_counts.lock().inc_view(window_id, view_id);
3876
3877        #[cfg(any(test, feature = "test-support"))]
3878        let handle_id = ref_counts
3879            .lock()
3880            .leak_detector
3881            .lock()
3882            .handle_created(None, view_id);
3883
3884        Self {
3885            window_id,
3886            view_id,
3887            view_type,
3888            ref_counts,
3889            #[cfg(any(test, feature = "test-support"))]
3890            handle_id,
3891        }
3892    }
3893
3894    pub fn window_id(&self) -> usize {
3895        self.window_id
3896    }
3897
3898    pub fn id(&self) -> usize {
3899        self.view_id
3900    }
3901
3902    pub fn is<T: 'static>(&self) -> bool {
3903        TypeId::of::<T>() == self.view_type
3904    }
3905
3906    pub fn downcast<T: View>(self) -> Option<ViewHandle<T>> {
3907        if self.is::<T>() {
3908            Some(ViewHandle {
3909                any_handle: self,
3910                view_type: PhantomData,
3911            })
3912        } else {
3913            None
3914        }
3915    }
3916
3917    pub fn downcast_ref<T: View>(&self) -> Option<&ViewHandle<T>> {
3918        if self.is::<T>() {
3919            Some(unsafe { mem::transmute(self) })
3920        } else {
3921            None
3922        }
3923    }
3924
3925    pub fn downgrade(&self) -> AnyWeakViewHandle {
3926        AnyWeakViewHandle {
3927            window_id: self.window_id,
3928            view_id: self.view_id,
3929            view_type: self.view_type,
3930        }
3931    }
3932
3933    pub fn view_type(&self) -> TypeId {
3934        self.view_type
3935    }
3936
3937    pub fn debug_json<'a, 'b>(&self, cx: &'b WindowContext<'a>) -> serde_json::Value {
3938        cx.views
3939            .get(&(self.window_id, self.view_id))
3940            .map_or_else(|| serde_json::Value::Null, |view| view.debug_json(cx))
3941    }
3942}
3943
3944impl Clone for AnyViewHandle {
3945    fn clone(&self) -> Self {
3946        Self::new(
3947            self.window_id,
3948            self.view_id,
3949            self.view_type,
3950            self.ref_counts.clone(),
3951        )
3952    }
3953}
3954
3955impl<T> PartialEq<ViewHandle<T>> for AnyViewHandle {
3956    fn eq(&self, other: &ViewHandle<T>) -> bool {
3957        self.window_id == other.window_id && self.view_id == other.view_id
3958    }
3959}
3960
3961impl Drop for AnyViewHandle {
3962    fn drop(&mut self) {
3963        self.ref_counts
3964            .lock()
3965            .dec_view(self.window_id, self.view_id);
3966        #[cfg(any(test, feature = "test-support"))]
3967        self.ref_counts
3968            .lock()
3969            .leak_detector
3970            .lock()
3971            .handle_dropped(self.view_id, self.handle_id);
3972    }
3973}
3974
3975impl Debug for AnyViewHandle {
3976    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
3977        f.debug_struct("AnyViewHandle")
3978            .field("window_id", &self.window_id)
3979            .field("view_id", &self.view_id)
3980            .finish()
3981    }
3982}
3983
3984pub struct AnyModelHandle {
3985    model_id: usize,
3986    model_type: TypeId,
3987    ref_counts: Arc<Mutex<RefCounts>>,
3988
3989    #[cfg(any(test, feature = "test-support"))]
3990    handle_id: usize,
3991}
3992
3993impl AnyModelHandle {
3994    fn new(model_id: usize, model_type: TypeId, ref_counts: Arc<Mutex<RefCounts>>) -> Self {
3995        ref_counts.lock().inc_model(model_id);
3996
3997        #[cfg(any(test, feature = "test-support"))]
3998        let handle_id = ref_counts
3999            .lock()
4000            .leak_detector
4001            .lock()
4002            .handle_created(None, model_id);
4003
4004        Self {
4005            model_id,
4006            model_type,
4007            ref_counts,
4008
4009            #[cfg(any(test, feature = "test-support"))]
4010            handle_id,
4011        }
4012    }
4013
4014    pub fn downcast<T: Entity>(self) -> Option<ModelHandle<T>> {
4015        if self.is::<T>() {
4016            Some(ModelHandle {
4017                any_handle: self,
4018                model_type: PhantomData,
4019            })
4020        } else {
4021            None
4022        }
4023    }
4024
4025    pub fn downgrade(&self) -> AnyWeakModelHandle {
4026        AnyWeakModelHandle {
4027            model_id: self.model_id,
4028            model_type: self.model_type,
4029        }
4030    }
4031
4032    pub fn is<T: Entity>(&self) -> bool {
4033        self.model_type == TypeId::of::<T>()
4034    }
4035
4036    pub fn model_type(&self) -> TypeId {
4037        self.model_type
4038    }
4039}
4040
4041impl Clone for AnyModelHandle {
4042    fn clone(&self) -> Self {
4043        Self::new(self.model_id, self.model_type, self.ref_counts.clone())
4044    }
4045}
4046
4047impl Drop for AnyModelHandle {
4048    fn drop(&mut self) {
4049        let mut ref_counts = self.ref_counts.lock();
4050        ref_counts.dec_model(self.model_id);
4051
4052        #[cfg(any(test, feature = "test-support"))]
4053        ref_counts
4054            .leak_detector
4055            .lock()
4056            .handle_dropped(self.model_id, self.handle_id);
4057    }
4058}
4059
4060#[derive(Hash, PartialEq, Eq, Debug, Clone, Copy)]
4061pub struct AnyWeakModelHandle {
4062    model_id: usize,
4063    model_type: TypeId,
4064}
4065
4066impl AnyWeakModelHandle {
4067    pub fn upgrade(&self, cx: &impl BorrowAppContext) -> Option<AnyModelHandle> {
4068        cx.read_with(|cx| cx.upgrade_any_model_handle(self))
4069    }
4070
4071    pub fn model_type(&self) -> TypeId {
4072        self.model_type
4073    }
4074
4075    fn is<T: 'static>(&self) -> bool {
4076        TypeId::of::<T>() == self.model_type
4077    }
4078
4079    pub fn downcast<T: Entity>(self) -> Option<WeakModelHandle<T>> {
4080        if self.is::<T>() {
4081            let result = Some(WeakModelHandle {
4082                any_handle: self,
4083                model_type: PhantomData,
4084            });
4085
4086            result
4087        } else {
4088            None
4089        }
4090    }
4091}
4092
4093#[derive(Copy)]
4094pub struct WeakViewHandle<T> {
4095    any_handle: AnyWeakViewHandle,
4096    view_type: PhantomData<T>,
4097}
4098
4099impl<T> Debug for WeakViewHandle<T> {
4100    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
4101        f.debug_struct(&format!("WeakViewHandle<{}>", type_name::<T>()))
4102            .field("any_handle", &self.any_handle)
4103            .finish()
4104    }
4105}
4106
4107impl<T> WeakHandle for WeakViewHandle<T> {
4108    fn id(&self) -> usize {
4109        self.view_id
4110    }
4111}
4112
4113impl<V: View> WeakViewHandle<V> {
4114    fn new(window_id: usize, view_id: usize) -> Self {
4115        Self {
4116            any_handle: AnyWeakViewHandle {
4117                window_id,
4118                view_id,
4119                view_type: TypeId::of::<V>(),
4120            },
4121            view_type: PhantomData,
4122        }
4123    }
4124
4125    pub fn id(&self) -> usize {
4126        self.view_id
4127    }
4128
4129    pub fn window_id(&self) -> usize {
4130        self.window_id
4131    }
4132
4133    pub fn into_any(self) -> AnyWeakViewHandle {
4134        self.any_handle
4135    }
4136
4137    pub fn upgrade(&self, cx: &impl BorrowAppContext) -> Option<ViewHandle<V>> {
4138        cx.read_with(|cx| cx.upgrade_view_handle(self))
4139    }
4140
4141    pub fn read_with<T>(
4142        &self,
4143        cx: &AsyncAppContext,
4144        read: impl FnOnce(&V, &ViewContext<V>) -> T,
4145    ) -> Result<T> {
4146        cx.read(|cx| {
4147            let handle = cx
4148                .upgrade_view_handle(self)
4149                .ok_or_else(|| anyhow!("view {} was dropped", V::ui_name()))?;
4150            cx.read_window(self.window_id, |cx| handle.read_with(cx, read))
4151                .ok_or_else(|| anyhow!("window was removed"))
4152        })
4153    }
4154
4155    pub fn update<T>(
4156        &self,
4157        cx: &mut AsyncAppContext,
4158        update: impl FnOnce(&mut V, &mut ViewContext<V>) -> T,
4159    ) -> Result<T> {
4160        cx.update(|cx| {
4161            let handle = cx
4162                .upgrade_view_handle(self)
4163                .ok_or_else(|| anyhow!("view {} was dropped", V::ui_name()))?;
4164            cx.update_window(self.window_id, |cx| handle.update(cx, update))
4165                .ok_or_else(|| anyhow!("window was removed"))
4166        })
4167    }
4168}
4169
4170impl<T> Deref for WeakViewHandle<T> {
4171    type Target = AnyWeakViewHandle;
4172
4173    fn deref(&self) -> &Self::Target {
4174        &self.any_handle
4175    }
4176}
4177
4178impl<T> Clone for WeakViewHandle<T> {
4179    fn clone(&self) -> Self {
4180        Self {
4181            any_handle: self.any_handle.clone(),
4182            view_type: PhantomData,
4183        }
4184    }
4185}
4186
4187impl<T> PartialEq for WeakViewHandle<T> {
4188    fn eq(&self, other: &Self) -> bool {
4189        self.window_id == other.window_id && self.view_id == other.view_id
4190    }
4191}
4192
4193impl<T> Eq for WeakViewHandle<T> {}
4194
4195impl<T> Hash for WeakViewHandle<T> {
4196    fn hash<H: Hasher>(&self, state: &mut H) {
4197        self.any_handle.hash(state);
4198    }
4199}
4200
4201#[derive(Debug, Clone, Copy)]
4202pub struct AnyWeakViewHandle {
4203    window_id: usize,
4204    view_id: usize,
4205    view_type: TypeId,
4206}
4207
4208impl AnyWeakViewHandle {
4209    pub fn id(&self) -> usize {
4210        self.view_id
4211    }
4212
4213    fn is<T: 'static>(&self) -> bool {
4214        TypeId::of::<T>() == self.view_type
4215    }
4216
4217    pub fn upgrade(&self, cx: &impl BorrowAppContext) -> Option<AnyViewHandle> {
4218        cx.read_with(|cx| cx.upgrade_any_view_handle(self))
4219    }
4220
4221    pub fn downcast<T: View>(self) -> Option<WeakViewHandle<T>> {
4222        if self.is::<T>() {
4223            Some(WeakViewHandle {
4224                any_handle: self,
4225                view_type: PhantomData,
4226            })
4227        } else {
4228            None
4229        }
4230    }
4231}
4232
4233impl Hash for AnyWeakViewHandle {
4234    fn hash<H: Hasher>(&self, state: &mut H) {
4235        self.window_id.hash(state);
4236        self.view_id.hash(state);
4237        self.view_type.hash(state);
4238    }
4239}
4240
4241#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
4242pub struct ElementStateId {
4243    view_id: usize,
4244    element_id: usize,
4245    tag: TypeId,
4246}
4247
4248pub struct ElementStateHandle<T> {
4249    value_type: PhantomData<T>,
4250    id: ElementStateId,
4251    ref_counts: Weak<Mutex<RefCounts>>,
4252}
4253
4254impl<T: 'static> ElementStateHandle<T> {
4255    fn new(id: ElementStateId, frame_id: usize, ref_counts: &Arc<Mutex<RefCounts>>) -> Self {
4256        ref_counts.lock().inc_element_state(id, frame_id);
4257        Self {
4258            value_type: PhantomData,
4259            id,
4260            ref_counts: Arc::downgrade(ref_counts),
4261        }
4262    }
4263
4264    pub fn id(&self) -> ElementStateId {
4265        self.id
4266    }
4267
4268    pub fn read<'a>(&self, cx: &'a AppContext) -> &'a T {
4269        cx.element_states
4270            .get(&self.id)
4271            .unwrap()
4272            .downcast_ref()
4273            .unwrap()
4274    }
4275
4276    pub fn update<C, D, R>(&self, cx: &mut C, f: impl FnOnce(&mut T, &mut C) -> R) -> R
4277    where
4278        C: DerefMut<Target = D>,
4279        D: DerefMut<Target = AppContext>,
4280    {
4281        let mut element_state = cx.deref_mut().element_states.remove(&self.id).unwrap();
4282        let result = f(element_state.downcast_mut().unwrap(), cx);
4283        cx.deref_mut().element_states.insert(self.id, element_state);
4284        result
4285    }
4286}
4287
4288impl<T> Drop for ElementStateHandle<T> {
4289    fn drop(&mut self) {
4290        if let Some(ref_counts) = self.ref_counts.upgrade() {
4291            ref_counts.lock().dec_element_state(self.id);
4292        }
4293    }
4294}
4295
4296#[must_use]
4297pub enum Subscription {
4298    Subscription(callback_collection::Subscription<usize, SubscriptionCallback>),
4299    Observation(callback_collection::Subscription<usize, ObservationCallback>),
4300    GlobalSubscription(callback_collection::Subscription<TypeId, GlobalSubscriptionCallback>),
4301    GlobalObservation(callback_collection::Subscription<TypeId, GlobalObservationCallback>),
4302    FocusObservation(callback_collection::Subscription<usize, FocusObservationCallback>),
4303    WindowActivationObservation(callback_collection::Subscription<usize, WindowActivationCallback>),
4304    WindowFullscreenObservation(callback_collection::Subscription<usize, WindowFullscreenCallback>),
4305    WindowBoundsObservation(callback_collection::Subscription<usize, WindowBoundsCallback>),
4306    KeystrokeObservation(callback_collection::Subscription<usize, KeystrokeCallback>),
4307    ReleaseObservation(callback_collection::Subscription<usize, ReleaseObservationCallback>),
4308    ActionObservation(callback_collection::Subscription<(), ActionObservationCallback>),
4309    ActiveLabeledTasksObservation(
4310        callback_collection::Subscription<(), ActiveLabeledTasksCallback>,
4311    ),
4312}
4313
4314impl Subscription {
4315    pub fn id(&self) -> usize {
4316        match self {
4317            Subscription::Subscription(subscription) => subscription.id(),
4318            Subscription::Observation(subscription) => subscription.id(),
4319            Subscription::GlobalSubscription(subscription) => subscription.id(),
4320            Subscription::GlobalObservation(subscription) => subscription.id(),
4321            Subscription::FocusObservation(subscription) => subscription.id(),
4322            Subscription::WindowActivationObservation(subscription) => subscription.id(),
4323            Subscription::WindowFullscreenObservation(subscription) => subscription.id(),
4324            Subscription::WindowBoundsObservation(subscription) => subscription.id(),
4325            Subscription::KeystrokeObservation(subscription) => subscription.id(),
4326            Subscription::ReleaseObservation(subscription) => subscription.id(),
4327            Subscription::ActionObservation(subscription) => subscription.id(),
4328            Subscription::ActiveLabeledTasksObservation(subscription) => subscription.id(),
4329        }
4330    }
4331
4332    pub fn detach(&mut self) {
4333        match self {
4334            Subscription::Subscription(subscription) => subscription.detach(),
4335            Subscription::GlobalSubscription(subscription) => subscription.detach(),
4336            Subscription::Observation(subscription) => subscription.detach(),
4337            Subscription::GlobalObservation(subscription) => subscription.detach(),
4338            Subscription::FocusObservation(subscription) => subscription.detach(),
4339            Subscription::KeystrokeObservation(subscription) => subscription.detach(),
4340            Subscription::WindowActivationObservation(subscription) => subscription.detach(),
4341            Subscription::WindowFullscreenObservation(subscription) => subscription.detach(),
4342            Subscription::WindowBoundsObservation(subscription) => subscription.detach(),
4343            Subscription::ReleaseObservation(subscription) => subscription.detach(),
4344            Subscription::ActionObservation(subscription) => subscription.detach(),
4345            Subscription::ActiveLabeledTasksObservation(subscription) => subscription.detach(),
4346        }
4347    }
4348}
4349
4350#[cfg(test)]
4351mod tests {
4352    use super::*;
4353    use crate::{
4354        actions,
4355        elements::*,
4356        impl_actions,
4357        platform::{MouseButton, MouseButtonEvent},
4358        window::ChildView,
4359    };
4360    use itertools::Itertools;
4361    use postage::{sink::Sink, stream::Stream};
4362    use serde::Deserialize;
4363    use smol::future::poll_once;
4364    use std::{
4365        cell::Cell,
4366        sync::atomic::{AtomicBool, AtomicUsize, Ordering::SeqCst},
4367    };
4368
4369    #[crate::test(self)]
4370    fn test_model_handles(cx: &mut AppContext) {
4371        struct Model {
4372            other: Option<ModelHandle<Model>>,
4373            events: Vec<String>,
4374        }
4375
4376        impl Entity for Model {
4377            type Event = usize;
4378        }
4379
4380        impl Model {
4381            fn new(other: Option<ModelHandle<Self>>, cx: &mut ModelContext<Self>) -> Self {
4382                if let Some(other) = other.as_ref() {
4383                    cx.observe(other, |me, _, _| {
4384                        me.events.push("notified".into());
4385                    })
4386                    .detach();
4387                    cx.subscribe(other, |me, _, event, _| {
4388                        me.events.push(format!("observed event {}", event));
4389                    })
4390                    .detach();
4391                }
4392
4393                Self {
4394                    other,
4395                    events: Vec::new(),
4396                }
4397            }
4398        }
4399
4400        let handle_1 = cx.add_model(|cx| Model::new(None, cx));
4401        let handle_2 = cx.add_model(|cx| Model::new(Some(handle_1.clone()), cx));
4402        assert_eq!(cx.models.len(), 2);
4403
4404        handle_1.update(cx, |model, cx| {
4405            model.events.push("updated".into());
4406            cx.emit(1);
4407            cx.notify();
4408            cx.emit(2);
4409        });
4410        assert_eq!(handle_1.read(cx).events, vec!["updated".to_string()]);
4411        assert_eq!(
4412            handle_2.read(cx).events,
4413            vec![
4414                "observed event 1".to_string(),
4415                "notified".to_string(),
4416                "observed event 2".to_string(),
4417            ]
4418        );
4419
4420        handle_2.update(cx, |model, _| {
4421            drop(handle_1);
4422            model.other.take();
4423        });
4424
4425        assert_eq!(cx.models.len(), 1);
4426        assert!(cx.subscriptions.is_empty());
4427        assert!(cx.observations.is_empty());
4428    }
4429
4430    #[crate::test(self)]
4431    fn test_model_events(cx: &mut AppContext) {
4432        #[derive(Default)]
4433        struct Model {
4434            events: Vec<usize>,
4435        }
4436
4437        impl Entity for Model {
4438            type Event = usize;
4439        }
4440
4441        let handle_1 = cx.add_model(|_| Model::default());
4442        let handle_2 = cx.add_model(|_| Model::default());
4443
4444        handle_1.update(cx, |_, cx| {
4445            cx.subscribe(&handle_2, move |model: &mut Model, emitter, event, cx| {
4446                model.events.push(*event);
4447
4448                cx.subscribe(&emitter, |model, _, event, _| {
4449                    model.events.push(*event * 2);
4450                })
4451                .detach();
4452            })
4453            .detach();
4454        });
4455
4456        handle_2.update(cx, |_, c| c.emit(7));
4457        assert_eq!(handle_1.read(cx).events, vec![7]);
4458
4459        handle_2.update(cx, |_, c| c.emit(5));
4460        assert_eq!(handle_1.read(cx).events, vec![7, 5, 10]);
4461    }
4462
4463    #[crate::test(self)]
4464    fn test_model_emit_before_subscribe_in_same_update_cycle(cx: &mut AppContext) {
4465        #[derive(Default)]
4466        struct Model;
4467
4468        impl Entity for Model {
4469            type Event = ();
4470        }
4471
4472        let events = Rc::new(RefCell::new(Vec::new()));
4473        cx.add_model(|cx| {
4474            drop(cx.subscribe(&cx.handle(), {
4475                let events = events.clone();
4476                move |_, _, _, _| events.borrow_mut().push("dropped before flush")
4477            }));
4478            cx.subscribe(&cx.handle(), {
4479                let events = events.clone();
4480                move |_, _, _, _| events.borrow_mut().push("before emit")
4481            })
4482            .detach();
4483            cx.emit(());
4484            cx.subscribe(&cx.handle(), {
4485                let events = events.clone();
4486                move |_, _, _, _| events.borrow_mut().push("after emit")
4487            })
4488            .detach();
4489            Model
4490        });
4491        assert_eq!(*events.borrow(), ["before emit"]);
4492    }
4493
4494    #[crate::test(self)]
4495    fn test_observe_and_notify_from_model(cx: &mut AppContext) {
4496        #[derive(Default)]
4497        struct Model {
4498            count: usize,
4499            events: Vec<usize>,
4500        }
4501
4502        impl Entity for Model {
4503            type Event = ();
4504        }
4505
4506        let handle_1 = cx.add_model(|_| Model::default());
4507        let handle_2 = cx.add_model(|_| Model::default());
4508
4509        handle_1.update(cx, |_, c| {
4510            c.observe(&handle_2, move |model, observed, c| {
4511                model.events.push(observed.read(c).count);
4512                c.observe(&observed, |model, observed, c| {
4513                    model.events.push(observed.read(c).count * 2);
4514                })
4515                .detach();
4516            })
4517            .detach();
4518        });
4519
4520        handle_2.update(cx, |model, c| {
4521            model.count = 7;
4522            c.notify()
4523        });
4524        assert_eq!(handle_1.read(cx).events, vec![7]);
4525
4526        handle_2.update(cx, |model, c| {
4527            model.count = 5;
4528            c.notify()
4529        });
4530        assert_eq!(handle_1.read(cx).events, vec![7, 5, 10])
4531    }
4532
4533    #[crate::test(self)]
4534    fn test_model_notify_before_observe_in_same_update_cycle(cx: &mut AppContext) {
4535        #[derive(Default)]
4536        struct Model;
4537
4538        impl Entity for Model {
4539            type Event = ();
4540        }
4541
4542        let events = Rc::new(RefCell::new(Vec::new()));
4543        cx.add_model(|cx| {
4544            drop(cx.observe(&cx.handle(), {
4545                let events = events.clone();
4546                move |_, _, _| events.borrow_mut().push("dropped before flush")
4547            }));
4548            cx.observe(&cx.handle(), {
4549                let events = events.clone();
4550                move |_, _, _| events.borrow_mut().push("before notify")
4551            })
4552            .detach();
4553            cx.notify();
4554            cx.observe(&cx.handle(), {
4555                let events = events.clone();
4556                move |_, _, _| events.borrow_mut().push("after notify")
4557            })
4558            .detach();
4559            Model
4560        });
4561        assert_eq!(*events.borrow(), ["before notify"]);
4562    }
4563
4564    #[crate::test(self)]
4565    fn test_defer_and_after_window_update(cx: &mut TestAppContext) {
4566        struct View {
4567            render_count: usize,
4568        }
4569
4570        impl Entity for View {
4571            type Event = usize;
4572        }
4573
4574        impl super::View for View {
4575            fn render(&mut self, _: &mut ViewContext<Self>) -> AnyElement<Self> {
4576                post_inc(&mut self.render_count);
4577                Empty::new().into_any()
4578            }
4579
4580            fn ui_name() -> &'static str {
4581                "View"
4582            }
4583        }
4584
4585        let (_, view) = cx.add_window(|_| View { render_count: 0 });
4586        let called_defer = Rc::new(AtomicBool::new(false));
4587        let called_after_window_update = Rc::new(AtomicBool::new(false));
4588
4589        view.update(cx, |this, cx| {
4590            assert_eq!(this.render_count, 1);
4591            cx.defer({
4592                let called_defer = called_defer.clone();
4593                move |this, _| {
4594                    assert_eq!(this.render_count, 1);
4595                    called_defer.store(true, SeqCst);
4596                }
4597            });
4598            cx.after_window_update({
4599                let called_after_window_update = called_after_window_update.clone();
4600                move |this, cx| {
4601                    assert_eq!(this.render_count, 2);
4602                    called_after_window_update.store(true, SeqCst);
4603                    cx.notify();
4604                }
4605            });
4606            assert!(!called_defer.load(SeqCst));
4607            assert!(!called_after_window_update.load(SeqCst));
4608            cx.notify();
4609        });
4610
4611        assert!(called_defer.load(SeqCst));
4612        assert!(called_after_window_update.load(SeqCst));
4613        assert_eq!(view.read_with(cx, |view, _| view.render_count), 3);
4614    }
4615
4616    #[crate::test(self)]
4617    fn test_view_handles(cx: &mut TestAppContext) {
4618        struct View {
4619            other: Option<ViewHandle<View>>,
4620            events: Vec<String>,
4621        }
4622
4623        impl Entity for View {
4624            type Event = usize;
4625        }
4626
4627        impl super::View for View {
4628            fn render(&mut self, _: &mut ViewContext<Self>) -> AnyElement<Self> {
4629                Empty::new().into_any()
4630            }
4631
4632            fn ui_name() -> &'static str {
4633                "View"
4634            }
4635        }
4636
4637        impl View {
4638            fn new(other: Option<ViewHandle<View>>, cx: &mut ViewContext<Self>) -> Self {
4639                if let Some(other) = other.as_ref() {
4640                    cx.subscribe(other, |me, _, event, _| {
4641                        me.events.push(format!("observed event {}", event));
4642                    })
4643                    .detach();
4644                }
4645                Self {
4646                    other,
4647                    events: Vec::new(),
4648                }
4649            }
4650        }
4651
4652        let (window_id, _root_view) = cx.add_window(|cx| View::new(None, cx));
4653        let handle_1 = cx.add_view(window_id, |cx| View::new(None, cx));
4654        let handle_2 = cx.add_view(window_id, |cx| View::new(Some(handle_1.clone()), cx));
4655        assert_eq!(cx.read(|cx| cx.views.len()), 3);
4656
4657        handle_1.update(cx, |view, cx| {
4658            view.events.push("updated".into());
4659            cx.emit(1);
4660            cx.emit(2);
4661        });
4662        handle_1.read_with(cx, |view, _| {
4663            assert_eq!(view.events, vec!["updated".to_string()]);
4664        });
4665        handle_2.read_with(cx, |view, _| {
4666            assert_eq!(
4667                view.events,
4668                vec![
4669                    "observed event 1".to_string(),
4670                    "observed event 2".to_string(),
4671                ]
4672            );
4673        });
4674
4675        handle_2.update(cx, |view, _| {
4676            drop(handle_1);
4677            view.other.take();
4678        });
4679
4680        cx.read(|cx| {
4681            assert_eq!(cx.views.len(), 2);
4682            assert!(cx.subscriptions.is_empty());
4683            assert!(cx.observations.is_empty());
4684        });
4685    }
4686
4687    #[crate::test(self)]
4688    fn test_add_window(cx: &mut AppContext) {
4689        struct View {
4690            mouse_down_count: Arc<AtomicUsize>,
4691        }
4692
4693        impl Entity for View {
4694            type Event = ();
4695        }
4696
4697        impl super::View for View {
4698            fn render(&mut self, cx: &mut ViewContext<Self>) -> AnyElement<Self> {
4699                enum Handler {}
4700                let mouse_down_count = self.mouse_down_count.clone();
4701                MouseEventHandler::<Handler, _>::new(0, cx, |_, _| Empty::new())
4702                    .on_down(MouseButton::Left, move |_, _, _| {
4703                        mouse_down_count.fetch_add(1, SeqCst);
4704                    })
4705                    .into_any()
4706            }
4707
4708            fn ui_name() -> &'static str {
4709                "View"
4710            }
4711        }
4712
4713        let mouse_down_count = Arc::new(AtomicUsize::new(0));
4714        let (window_id, _) = cx.add_window(Default::default(), |_| View {
4715            mouse_down_count: mouse_down_count.clone(),
4716        });
4717
4718        cx.update_window(window_id, |cx| {
4719            // Ensure window's root element is in a valid lifecycle state.
4720            cx.dispatch_event(
4721                Event::MouseDown(MouseButtonEvent {
4722                    position: Default::default(),
4723                    button: MouseButton::Left,
4724                    modifiers: Default::default(),
4725                    click_count: 1,
4726                }),
4727                false,
4728            );
4729            assert_eq!(mouse_down_count.load(SeqCst), 1);
4730        });
4731    }
4732
4733    #[crate::test(self)]
4734    fn test_entity_release_hooks(cx: &mut AppContext) {
4735        struct Model {
4736            released: Rc<Cell<bool>>,
4737        }
4738
4739        struct View {
4740            released: Rc<Cell<bool>>,
4741        }
4742
4743        impl Entity for Model {
4744            type Event = ();
4745
4746            fn release(&mut self, _: &mut AppContext) {
4747                self.released.set(true);
4748            }
4749        }
4750
4751        impl Entity for View {
4752            type Event = ();
4753
4754            fn release(&mut self, _: &mut AppContext) {
4755                self.released.set(true);
4756            }
4757        }
4758
4759        impl super::View for View {
4760            fn ui_name() -> &'static str {
4761                "View"
4762            }
4763
4764            fn render(&mut self, _: &mut ViewContext<Self>) -> AnyElement<Self> {
4765                Empty::new().into_any()
4766            }
4767        }
4768
4769        let model_released = Rc::new(Cell::new(false));
4770        let model_release_observed = Rc::new(Cell::new(false));
4771        let view_released = Rc::new(Cell::new(false));
4772        let view_release_observed = Rc::new(Cell::new(false));
4773
4774        let model = cx.add_model(|_| Model {
4775            released: model_released.clone(),
4776        });
4777        let (window_id, view) = cx.add_window(Default::default(), |_| View {
4778            released: view_released.clone(),
4779        });
4780        assert!(!model_released.get());
4781        assert!(!view_released.get());
4782
4783        cx.observe_release(&model, {
4784            let model_release_observed = model_release_observed.clone();
4785            move |_, _| model_release_observed.set(true)
4786        })
4787        .detach();
4788        cx.observe_release(&view, {
4789            let view_release_observed = view_release_observed.clone();
4790            move |_, _| view_release_observed.set(true)
4791        })
4792        .detach();
4793
4794        cx.update(move |_| {
4795            drop(model);
4796        });
4797        assert!(model_released.get());
4798        assert!(model_release_observed.get());
4799
4800        drop(view);
4801        cx.update_window(window_id, |cx| cx.remove_window());
4802        assert!(view_released.get());
4803        assert!(view_release_observed.get());
4804    }
4805
4806    #[crate::test(self)]
4807    fn test_view_events(cx: &mut TestAppContext) {
4808        struct Model;
4809
4810        impl Entity for Model {
4811            type Event = String;
4812        }
4813
4814        let (window_id, handle_1) = cx.add_window(|_| TestView::default());
4815        let handle_2 = cx.add_view(window_id, |_| TestView::default());
4816        let handle_3 = cx.add_model(|_| Model);
4817
4818        handle_1.update(cx, |_, cx| {
4819            cx.subscribe(&handle_2, move |me, emitter, event, cx| {
4820                me.events.push(event.clone());
4821
4822                cx.subscribe(&emitter, |me, _, event, _| {
4823                    me.events.push(format!("{event} from inner"));
4824                })
4825                .detach();
4826            })
4827            .detach();
4828
4829            cx.subscribe(&handle_3, |me, _, event, _| {
4830                me.events.push(event.clone());
4831            })
4832            .detach();
4833        });
4834
4835        handle_2.update(cx, |_, c| c.emit("7".into()));
4836        handle_1.read_with(cx, |view, _| assert_eq!(view.events, ["7"]));
4837
4838        handle_2.update(cx, |_, c| c.emit("5".into()));
4839        handle_1.read_with(cx, |view, _| {
4840            assert_eq!(view.events, ["7", "5", "5 from inner"])
4841        });
4842
4843        handle_3.update(cx, |_, c| c.emit("9".into()));
4844        handle_1.read_with(cx, |view, _| {
4845            assert_eq!(view.events, ["7", "5", "5 from inner", "9"])
4846        });
4847    }
4848
4849    #[crate::test(self)]
4850    fn test_global_events(cx: &mut AppContext) {
4851        #[derive(Clone, Debug, Eq, PartialEq)]
4852        struct GlobalEvent(u64);
4853
4854        let events = Rc::new(RefCell::new(Vec::new()));
4855        let first_subscription;
4856        let second_subscription;
4857
4858        {
4859            let events = events.clone();
4860            first_subscription = cx.subscribe_global(move |e: &GlobalEvent, _| {
4861                events.borrow_mut().push(("First", e.clone()));
4862            });
4863        }
4864
4865        {
4866            let events = events.clone();
4867            second_subscription = cx.subscribe_global(move |e: &GlobalEvent, _| {
4868                events.borrow_mut().push(("Second", e.clone()));
4869            });
4870        }
4871
4872        cx.update(|cx| {
4873            cx.emit_global(GlobalEvent(1));
4874            cx.emit_global(GlobalEvent(2));
4875        });
4876
4877        drop(first_subscription);
4878
4879        cx.update(|cx| {
4880            cx.emit_global(GlobalEvent(3));
4881        });
4882
4883        drop(second_subscription);
4884
4885        cx.update(|cx| {
4886            cx.emit_global(GlobalEvent(4));
4887        });
4888
4889        assert_eq!(
4890            &*events.borrow(),
4891            &[
4892                ("First", GlobalEvent(1)),
4893                ("Second", GlobalEvent(1)),
4894                ("First", GlobalEvent(2)),
4895                ("Second", GlobalEvent(2)),
4896                ("Second", GlobalEvent(3)),
4897            ]
4898        );
4899    }
4900
4901    #[crate::test(self)]
4902    fn test_global_events_emitted_before_subscription_in_same_update_cycle(cx: &mut AppContext) {
4903        let events = Rc::new(RefCell::new(Vec::new()));
4904        cx.update(|cx| {
4905            {
4906                let events = events.clone();
4907                drop(cx.subscribe_global(move |_: &(), _| {
4908                    events.borrow_mut().push("dropped before emit");
4909                }));
4910            }
4911
4912            {
4913                let events = events.clone();
4914                cx.subscribe_global(move |_: &(), _| {
4915                    events.borrow_mut().push("before emit");
4916                })
4917                .detach();
4918            }
4919
4920            cx.emit_global(());
4921
4922            {
4923                let events = events.clone();
4924                cx.subscribe_global(move |_: &(), _| {
4925                    events.borrow_mut().push("after emit");
4926                })
4927                .detach();
4928            }
4929        });
4930
4931        assert_eq!(*events.borrow(), ["before emit"]);
4932    }
4933
4934    #[crate::test(self)]
4935    fn test_global_nested_events(cx: &mut AppContext) {
4936        #[derive(Clone, Debug, Eq, PartialEq)]
4937        struct GlobalEvent(u64);
4938
4939        let events = Rc::new(RefCell::new(Vec::new()));
4940
4941        {
4942            let events = events.clone();
4943            cx.subscribe_global(move |e: &GlobalEvent, cx| {
4944                events.borrow_mut().push(("Outer", e.clone()));
4945
4946                if e.0 == 1 {
4947                    let events = events.clone();
4948                    cx.subscribe_global(move |e: &GlobalEvent, _| {
4949                        events.borrow_mut().push(("Inner", e.clone()));
4950                    })
4951                    .detach();
4952                }
4953            })
4954            .detach();
4955        }
4956
4957        cx.update(|cx| {
4958            cx.emit_global(GlobalEvent(1));
4959            cx.emit_global(GlobalEvent(2));
4960            cx.emit_global(GlobalEvent(3));
4961        });
4962        cx.update(|cx| {
4963            cx.emit_global(GlobalEvent(4));
4964        });
4965
4966        assert_eq!(
4967            &*events.borrow(),
4968            &[
4969                ("Outer", GlobalEvent(1)),
4970                ("Outer", GlobalEvent(2)),
4971                ("Outer", GlobalEvent(3)),
4972                ("Outer", GlobalEvent(4)),
4973                ("Inner", GlobalEvent(4)),
4974            ]
4975        );
4976    }
4977
4978    #[crate::test(self)]
4979    fn test_global(cx: &mut AppContext) {
4980        type Global = usize;
4981
4982        let observation_count = Rc::new(RefCell::new(0));
4983        let subscription = cx.observe_global::<Global, _>({
4984            let observation_count = observation_count.clone();
4985            move |_| {
4986                *observation_count.borrow_mut() += 1;
4987            }
4988        });
4989
4990        assert!(!cx.has_global::<Global>());
4991        assert_eq!(cx.default_global::<Global>(), &0);
4992        assert_eq!(*observation_count.borrow(), 1);
4993        assert!(cx.has_global::<Global>());
4994        assert_eq!(
4995            cx.update_global::<Global, _, _>(|global, _| {
4996                *global = 1;
4997                "Update Result"
4998            }),
4999            "Update Result"
5000        );
5001        assert_eq!(*observation_count.borrow(), 2);
5002        assert_eq!(cx.global::<Global>(), &1);
5003
5004        drop(subscription);
5005        cx.update_global::<Global, _, _>(|global, _| {
5006            *global = 2;
5007        });
5008        assert_eq!(*observation_count.borrow(), 2);
5009
5010        type OtherGlobal = f32;
5011
5012        let observation_count = Rc::new(RefCell::new(0));
5013        cx.observe_global::<OtherGlobal, _>({
5014            let observation_count = observation_count.clone();
5015            move |_| {
5016                *observation_count.borrow_mut() += 1;
5017            }
5018        })
5019        .detach();
5020
5021        assert_eq!(
5022            cx.update_default_global::<OtherGlobal, _, _>(|global, _| {
5023                assert_eq!(global, &0.0);
5024                *global = 2.0;
5025                "Default update result"
5026            }),
5027            "Default update result"
5028        );
5029        assert_eq!(cx.global::<OtherGlobal>(), &2.0);
5030        assert_eq!(*observation_count.borrow(), 1);
5031    }
5032
5033    #[crate::test(self)]
5034    fn test_dropping_subscribers(cx: &mut TestAppContext) {
5035        struct Model;
5036
5037        impl Entity for Model {
5038            type Event = ();
5039        }
5040
5041        let (window_id, _root_view) = cx.add_window(|_| TestView::default());
5042        let observing_view = cx.add_view(window_id, |_| TestView::default());
5043        let emitting_view = cx.add_view(window_id, |_| TestView::default());
5044        let observing_model = cx.add_model(|_| Model);
5045        let observed_model = cx.add_model(|_| Model);
5046
5047        observing_view.update(cx, |_, cx| {
5048            cx.subscribe(&emitting_view, |_, _, _, _| {}).detach();
5049            cx.subscribe(&observed_model, |_, _, _, _| {}).detach();
5050        });
5051        observing_model.update(cx, |_, cx| {
5052            cx.subscribe(&observed_model, |_, _, _, _| {}).detach();
5053        });
5054
5055        cx.update(|_| {
5056            drop(observing_view);
5057            drop(observing_model);
5058        });
5059
5060        emitting_view.update(cx, |_, cx| cx.emit(Default::default()));
5061        observed_model.update(cx, |_, cx| cx.emit(()));
5062    }
5063
5064    #[crate::test(self)]
5065    fn test_view_emit_before_subscribe_in_same_update_cycle(cx: &mut AppContext) {
5066        let (_, view) = cx.add_window::<TestView, _>(Default::default(), |cx| {
5067            drop(cx.subscribe(&cx.handle(), {
5068                move |this, _, _, _| this.events.push("dropped before flush".into())
5069            }));
5070            cx.subscribe(&cx.handle(), {
5071                move |this, _, _, _| this.events.push("before emit".into())
5072            })
5073            .detach();
5074            cx.emit("the event".into());
5075            cx.subscribe(&cx.handle(), {
5076                move |this, _, _, _| this.events.push("after emit".into())
5077            })
5078            .detach();
5079            TestView { events: Vec::new() }
5080        });
5081
5082        assert_eq!(view.read(cx).events, ["before emit"]);
5083    }
5084
5085    #[crate::test(self)]
5086    fn test_observe_and_notify_from_view(cx: &mut TestAppContext) {
5087        #[derive(Default)]
5088        struct Model {
5089            state: String,
5090        }
5091
5092        impl Entity for Model {
5093            type Event = ();
5094        }
5095
5096        let (_, view) = cx.add_window(|_| TestView::default());
5097        let model = cx.add_model(|_| Model {
5098            state: "old-state".into(),
5099        });
5100
5101        view.update(cx, |_, c| {
5102            c.observe(&model, |me, observed, cx| {
5103                me.events.push(observed.read(cx).state.clone())
5104            })
5105            .detach();
5106        });
5107
5108        model.update(cx, |model, cx| {
5109            model.state = "new-state".into();
5110            cx.notify();
5111        });
5112        view.read_with(cx, |view, _| assert_eq!(view.events, ["new-state"]));
5113    }
5114
5115    #[crate::test(self)]
5116    fn test_view_notify_before_observe_in_same_update_cycle(cx: &mut AppContext) {
5117        let (_, view) = cx.add_window::<TestView, _>(Default::default(), |cx| {
5118            drop(cx.observe(&cx.handle(), {
5119                move |this, _, _| this.events.push("dropped before flush".into())
5120            }));
5121            cx.observe(&cx.handle(), {
5122                move |this, _, _| this.events.push("before notify".into())
5123            })
5124            .detach();
5125            cx.notify();
5126            cx.observe(&cx.handle(), {
5127                move |this, _, _| this.events.push("after notify".into())
5128            })
5129            .detach();
5130            TestView { events: Vec::new() }
5131        });
5132
5133        assert_eq!(view.read(cx).events, ["before notify"]);
5134    }
5135
5136    #[crate::test(self)]
5137    fn test_notify_and_drop_observe_subscription_in_same_update_cycle(cx: &mut TestAppContext) {
5138        struct Model;
5139        impl Entity for Model {
5140            type Event = ();
5141        }
5142
5143        let model = cx.add_model(|_| Model);
5144        let (_, view) = cx.add_window(|_| TestView::default());
5145
5146        view.update(cx, |_, cx| {
5147            model.update(cx, |_, cx| cx.notify());
5148            drop(cx.observe(&model, move |this, _, _| {
5149                this.events.push("model notified".into());
5150            }));
5151            model.update(cx, |_, cx| cx.notify());
5152        });
5153
5154        for _ in 0..3 {
5155            model.update(cx, |_, cx| cx.notify());
5156        }
5157        view.read_with(cx, |view, _| assert_eq!(view.events, Vec::<&str>::new()));
5158    }
5159
5160    #[crate::test(self)]
5161    fn test_dropping_observers(cx: &mut TestAppContext) {
5162        struct Model;
5163
5164        impl Entity for Model {
5165            type Event = ();
5166        }
5167
5168        let (window_id, _root_view) = cx.add_window(|_| TestView::default());
5169        let observing_view = cx.add_view(window_id, |_| TestView::default());
5170        let observing_model = cx.add_model(|_| Model);
5171        let observed_model = cx.add_model(|_| Model);
5172
5173        observing_view.update(cx, |_, cx| {
5174            cx.observe(&observed_model, |_, _, _| {}).detach();
5175        });
5176        observing_model.update(cx, |_, cx| {
5177            cx.observe(&observed_model, |_, _, _| {}).detach();
5178        });
5179
5180        cx.update(|_| {
5181            drop(observing_view);
5182            drop(observing_model);
5183        });
5184
5185        observed_model.update(cx, |_, cx| cx.notify());
5186    }
5187
5188    #[crate::test(self)]
5189    fn test_dropping_subscriptions_during_callback(cx: &mut TestAppContext) {
5190        struct Model;
5191
5192        impl Entity for Model {
5193            type Event = u64;
5194        }
5195
5196        // Events
5197        let observing_model = cx.add_model(|_| Model);
5198        let observed_model = cx.add_model(|_| Model);
5199
5200        let events = Rc::new(RefCell::new(Vec::new()));
5201
5202        observing_model.update(cx, |_, cx| {
5203            let events = events.clone();
5204            let subscription = Rc::new(RefCell::new(None));
5205            *subscription.borrow_mut() = Some(cx.subscribe(&observed_model, {
5206                let subscription = subscription.clone();
5207                move |_, _, e, _| {
5208                    subscription.borrow_mut().take();
5209                    events.borrow_mut().push(*e);
5210                }
5211            }));
5212        });
5213
5214        observed_model.update(cx, |_, cx| {
5215            cx.emit(1);
5216            cx.emit(2);
5217        });
5218
5219        assert_eq!(*events.borrow(), [1]);
5220
5221        // Global Events
5222        #[derive(Clone, Debug, Eq, PartialEq)]
5223        struct GlobalEvent(u64);
5224
5225        let events = Rc::new(RefCell::new(Vec::new()));
5226
5227        {
5228            let events = events.clone();
5229            let subscription = Rc::new(RefCell::new(None));
5230            *subscription.borrow_mut() = Some(cx.subscribe_global({
5231                let subscription = subscription.clone();
5232                move |e: &GlobalEvent, _| {
5233                    subscription.borrow_mut().take();
5234                    events.borrow_mut().push(e.clone());
5235                }
5236            }));
5237        }
5238
5239        cx.update(|cx| {
5240            cx.emit_global(GlobalEvent(1));
5241            cx.emit_global(GlobalEvent(2));
5242        });
5243
5244        assert_eq!(*events.borrow(), [GlobalEvent(1)]);
5245
5246        // Model Observation
5247        let observing_model = cx.add_model(|_| Model);
5248        let observed_model = cx.add_model(|_| Model);
5249
5250        let observation_count = Rc::new(RefCell::new(0));
5251
5252        observing_model.update(cx, |_, cx| {
5253            let observation_count = observation_count.clone();
5254            let subscription = Rc::new(RefCell::new(None));
5255            *subscription.borrow_mut() = Some(cx.observe(&observed_model, {
5256                let subscription = subscription.clone();
5257                move |_, _, _| {
5258                    subscription.borrow_mut().take();
5259                    *observation_count.borrow_mut() += 1;
5260                }
5261            }));
5262        });
5263
5264        observed_model.update(cx, |_, cx| {
5265            cx.notify();
5266        });
5267
5268        observed_model.update(cx, |_, cx| {
5269            cx.notify();
5270        });
5271
5272        assert_eq!(*observation_count.borrow(), 1);
5273
5274        // View Observation
5275        struct View;
5276
5277        impl Entity for View {
5278            type Event = ();
5279        }
5280
5281        impl super::View for View {
5282            fn render(&mut self, _: &mut ViewContext<Self>) -> AnyElement<Self> {
5283                Empty::new().into_any()
5284            }
5285
5286            fn ui_name() -> &'static str {
5287                "View"
5288            }
5289        }
5290
5291        let (window_id, _root_view) = cx.add_window(|_| View);
5292        let observing_view = cx.add_view(window_id, |_| View);
5293        let observed_view = cx.add_view(window_id, |_| View);
5294
5295        let observation_count = Rc::new(RefCell::new(0));
5296        observing_view.update(cx, |_, cx| {
5297            let observation_count = observation_count.clone();
5298            let subscription = Rc::new(RefCell::new(None));
5299            *subscription.borrow_mut() = Some(cx.observe(&observed_view, {
5300                let subscription = subscription.clone();
5301                move |_, _, _| {
5302                    subscription.borrow_mut().take();
5303                    *observation_count.borrow_mut() += 1;
5304                }
5305            }));
5306        });
5307
5308        observed_view.update(cx, |_, cx| {
5309            cx.notify();
5310        });
5311
5312        observed_view.update(cx, |_, cx| {
5313            cx.notify();
5314        });
5315
5316        assert_eq!(*observation_count.borrow(), 1);
5317
5318        // Global Observation
5319        let observation_count = Rc::new(RefCell::new(0));
5320        let subscription = Rc::new(RefCell::new(None));
5321        *subscription.borrow_mut() = Some(cx.observe_global::<(), _>({
5322            let observation_count = observation_count.clone();
5323            let subscription = subscription.clone();
5324            move |_| {
5325                subscription.borrow_mut().take();
5326                *observation_count.borrow_mut() += 1;
5327            }
5328        }));
5329
5330        cx.update(|cx| {
5331            cx.default_global::<()>();
5332            cx.set_global(());
5333        });
5334        assert_eq!(*observation_count.borrow(), 1);
5335    }
5336
5337    #[crate::test(self)]
5338    fn test_focus(cx: &mut TestAppContext) {
5339        struct View {
5340            name: String,
5341            events: Arc<Mutex<Vec<String>>>,
5342            child: Option<AnyViewHandle>,
5343        }
5344
5345        impl Entity for View {
5346            type Event = ();
5347        }
5348
5349        impl super::View for View {
5350            fn render(&mut self, cx: &mut ViewContext<Self>) -> AnyElement<Self> {
5351                self.child
5352                    .as_ref()
5353                    .map(|child| ChildView::new(child, cx).into_any())
5354                    .unwrap_or(Empty::new().into_any())
5355            }
5356
5357            fn ui_name() -> &'static str {
5358                "View"
5359            }
5360
5361            fn focus_in(&mut self, focused: AnyViewHandle, cx: &mut ViewContext<Self>) {
5362                if cx.handle().id() == focused.id() {
5363                    self.events.lock().push(format!("{} focused", &self.name));
5364                }
5365            }
5366
5367            fn focus_out(&mut self, blurred: AnyViewHandle, cx: &mut ViewContext<Self>) {
5368                if cx.handle().id() == blurred.id() {
5369                    self.events.lock().push(format!("{} blurred", &self.name));
5370                }
5371            }
5372        }
5373
5374        let view_events: Arc<Mutex<Vec<String>>> = Default::default();
5375        let (window_id, view_1) = cx.add_window(|_| View {
5376            events: view_events.clone(),
5377            name: "view 1".to_string(),
5378            child: None,
5379        });
5380        let view_2 = cx
5381            .update_window(window_id, |cx| {
5382                let view_2 = cx.add_view(|_| View {
5383                    events: view_events.clone(),
5384                    name: "view 2".to_string(),
5385                    child: None,
5386                });
5387                view_1.update(cx, |view_1, cx| {
5388                    view_1.child = Some(view_2.clone().into_any());
5389                    cx.notify();
5390                });
5391                view_2
5392            })
5393            .unwrap();
5394
5395        let observed_events: Arc<Mutex<Vec<String>>> = Default::default();
5396        view_1.update(cx, |_, cx| {
5397            cx.observe_focus(&view_2, {
5398                let observed_events = observed_events.clone();
5399                move |this, view, focused, cx| {
5400                    let label = if focused { "focus" } else { "blur" };
5401                    observed_events.lock().push(format!(
5402                        "{} observed {}'s {}",
5403                        this.name,
5404                        view.read(cx).name,
5405                        label
5406                    ))
5407                }
5408            })
5409            .detach();
5410        });
5411        view_2.update(cx, |_, cx| {
5412            cx.observe_focus(&view_1, {
5413                let observed_events = observed_events.clone();
5414                move |this, view, focused, cx| {
5415                    let label = if focused { "focus" } else { "blur" };
5416                    observed_events.lock().push(format!(
5417                        "{} observed {}'s {}",
5418                        this.name,
5419                        view.read(cx).name,
5420                        label
5421                    ))
5422                }
5423            })
5424            .detach();
5425        });
5426        assert_eq!(mem::take(&mut *view_events.lock()), ["view 1 focused"]);
5427        assert_eq!(mem::take(&mut *observed_events.lock()), Vec::<&str>::new());
5428
5429        view_1.update(cx, |_, cx| {
5430            // Ensure only the last focus event is honored.
5431            cx.focus(&view_2);
5432            cx.focus(&view_1);
5433            cx.focus(&view_2);
5434        });
5435
5436        assert_eq!(
5437            mem::take(&mut *view_events.lock()),
5438            ["view 1 blurred", "view 2 focused"],
5439        );
5440        assert_eq!(
5441            mem::take(&mut *observed_events.lock()),
5442            [
5443                "view 2 observed view 1's blur",
5444                "view 1 observed view 2's focus"
5445            ]
5446        );
5447
5448        view_1.update(cx, |_, cx| cx.focus(&view_1));
5449        assert_eq!(
5450            mem::take(&mut *view_events.lock()),
5451            ["view 2 blurred", "view 1 focused"],
5452        );
5453        assert_eq!(
5454            mem::take(&mut *observed_events.lock()),
5455            [
5456                "view 1 observed view 2's blur",
5457                "view 2 observed view 1's focus"
5458            ]
5459        );
5460
5461        view_1.update(cx, |_, cx| cx.focus(&view_2));
5462        assert_eq!(
5463            mem::take(&mut *view_events.lock()),
5464            ["view 1 blurred", "view 2 focused"],
5465        );
5466        assert_eq!(
5467            mem::take(&mut *observed_events.lock()),
5468            [
5469                "view 2 observed view 1's blur",
5470                "view 1 observed view 2's focus"
5471            ]
5472        );
5473
5474        println!("=====================");
5475        view_1.update(cx, |view, _| {
5476            drop(view_2);
5477            view.child = None;
5478        });
5479        assert_eq!(mem::take(&mut *view_events.lock()), ["view 1 focused"]);
5480        assert_eq!(mem::take(&mut *observed_events.lock()), Vec::<&str>::new());
5481    }
5482
5483    #[crate::test(self)]
5484    fn test_deserialize_actions(cx: &mut AppContext) {
5485        #[derive(Clone, Debug, Deserialize, PartialEq, Eq)]
5486        pub struct ComplexAction {
5487            arg: String,
5488            count: usize,
5489        }
5490
5491        actions!(test::something, [SimpleAction]);
5492        impl_actions!(test::something, [ComplexAction]);
5493
5494        cx.add_global_action(move |_: &SimpleAction, _: &mut AppContext| {});
5495        cx.add_global_action(move |_: &ComplexAction, _: &mut AppContext| {});
5496
5497        let action1 = cx
5498            .deserialize_action(
5499                "test::something::ComplexAction",
5500                Some(r#"{"arg": "a", "count": 5}"#),
5501            )
5502            .unwrap();
5503        let action2 = cx
5504            .deserialize_action("test::something::SimpleAction", None)
5505            .unwrap();
5506        assert_eq!(
5507            action1.as_any().downcast_ref::<ComplexAction>().unwrap(),
5508            &ComplexAction {
5509                arg: "a".to_string(),
5510                count: 5,
5511            }
5512        );
5513        assert_eq!(
5514            action2.as_any().downcast_ref::<SimpleAction>().unwrap(),
5515            &SimpleAction
5516        );
5517    }
5518
5519    #[crate::test(self)]
5520    fn test_dispatch_action(cx: &mut AppContext) {
5521        struct ViewA {
5522            id: usize,
5523            child: Option<AnyViewHandle>,
5524        }
5525
5526        impl Entity for ViewA {
5527            type Event = ();
5528        }
5529
5530        impl View for ViewA {
5531            fn render(&mut self, cx: &mut ViewContext<Self>) -> AnyElement<Self> {
5532                self.child
5533                    .as_ref()
5534                    .map(|child| ChildView::new(child, cx).into_any())
5535                    .unwrap_or(Empty::new().into_any())
5536            }
5537
5538            fn ui_name() -> &'static str {
5539                "View"
5540            }
5541        }
5542
5543        struct ViewB {
5544            id: usize,
5545            child: Option<AnyViewHandle>,
5546        }
5547
5548        impl Entity for ViewB {
5549            type Event = ();
5550        }
5551
5552        impl View for ViewB {
5553            fn render(&mut self, cx: &mut ViewContext<Self>) -> AnyElement<Self> {
5554                self.child
5555                    .as_ref()
5556                    .map(|child| ChildView::new(child, cx).into_any())
5557                    .unwrap_or(Empty::new().into_any())
5558            }
5559
5560            fn ui_name() -> &'static str {
5561                "View"
5562            }
5563        }
5564
5565        #[derive(Clone, Default, Deserialize, PartialEq)]
5566        pub struct Action(pub String);
5567
5568        impl_actions!(test, [Action]);
5569
5570        let actions = Rc::new(RefCell::new(Vec::new()));
5571
5572        cx.add_global_action({
5573            let actions = actions.clone();
5574            move |_: &Action, _: &mut AppContext| {
5575                actions.borrow_mut().push("global".to_string());
5576            }
5577        });
5578
5579        cx.add_action({
5580            let actions = actions.clone();
5581            move |view: &mut ViewA, action: &Action, cx| {
5582                assert_eq!(action.0, "bar");
5583                cx.propagate_action();
5584                actions.borrow_mut().push(format!("{} a", view.id));
5585            }
5586        });
5587
5588        cx.add_action({
5589            let actions = actions.clone();
5590            move |view: &mut ViewA, _: &Action, cx| {
5591                if view.id != 1 {
5592                    cx.add_view(|cx| {
5593                        cx.propagate_action(); // Still works on a nested ViewContext
5594                        ViewB { id: 5, child: None }
5595                    });
5596                }
5597                actions.borrow_mut().push(format!("{} b", view.id));
5598            }
5599        });
5600
5601        cx.add_action({
5602            let actions = actions.clone();
5603            move |view: &mut ViewB, _: &Action, cx| {
5604                cx.propagate_action();
5605                actions.borrow_mut().push(format!("{} c", view.id));
5606            }
5607        });
5608
5609        cx.add_action({
5610            let actions = actions.clone();
5611            move |view: &mut ViewB, _: &Action, cx| {
5612                cx.propagate_action();
5613                actions.borrow_mut().push(format!("{} d", view.id));
5614            }
5615        });
5616
5617        cx.capture_action({
5618            let actions = actions.clone();
5619            move |view: &mut ViewA, _: &Action, cx| {
5620                cx.propagate_action();
5621                actions.borrow_mut().push(format!("{} capture", view.id));
5622            }
5623        });
5624
5625        let observed_actions = Rc::new(RefCell::new(Vec::new()));
5626        cx.observe_actions({
5627            let observed_actions = observed_actions.clone();
5628            move |action_id, _| observed_actions.borrow_mut().push(action_id)
5629        })
5630        .detach();
5631
5632        let (window_id, view_1) =
5633            cx.add_window(Default::default(), |_| ViewA { id: 1, child: None });
5634        let view_2 = cx
5635            .update_window(window_id, |cx| {
5636                let child = cx.add_view(|_| ViewB { id: 2, child: None });
5637                view_1.update(cx, |view, cx| {
5638                    view.child = Some(child.clone().into_any());
5639                    cx.notify();
5640                });
5641                child
5642            })
5643            .unwrap();
5644        let view_3 = cx
5645            .update_window(window_id, |cx| {
5646                let child = cx.add_view(|_| ViewA { id: 3, child: None });
5647                view_2.update(cx, |view, cx| {
5648                    view.child = Some(child.clone().into_any());
5649                    cx.notify();
5650                });
5651                child
5652            })
5653            .unwrap();
5654        let view_4 = cx
5655            .update_window(window_id, |cx| {
5656                let child = cx.add_view(|_| ViewB { id: 4, child: None });
5657                view_3.update(cx, |view, cx| {
5658                    view.child = Some(child.clone().into_any());
5659                    cx.notify();
5660                });
5661                child
5662            })
5663            .unwrap();
5664
5665        cx.update_window(window_id, |cx| {
5666            cx.dispatch_action(Some(view_4.id()), &Action("bar".to_string()))
5667        });
5668
5669        assert_eq!(
5670            *actions.borrow(),
5671            vec![
5672                "1 capture",
5673                "3 capture",
5674                "4 d",
5675                "4 c",
5676                "3 b",
5677                "3 a",
5678                "2 d",
5679                "2 c",
5680                "1 b"
5681            ]
5682        );
5683        assert_eq!(*observed_actions.borrow(), [Action::default().id()]);
5684
5685        // Remove view_1, which doesn't propagate the action
5686
5687        let (window_id, view_2) =
5688            cx.add_window(Default::default(), |_| ViewB { id: 2, child: None });
5689        let view_3 = cx
5690            .update_window(window_id, |cx| {
5691                let child = cx.add_view(|_| ViewA { id: 3, child: None });
5692                view_2.update(cx, |view, cx| {
5693                    view.child = Some(child.clone().into_any());
5694                    cx.notify();
5695                });
5696                child
5697            })
5698            .unwrap();
5699        let view_4 = cx
5700            .update_window(window_id, |cx| {
5701                let child = cx.add_view(|_| ViewB { id: 4, child: None });
5702                view_3.update(cx, |view, cx| {
5703                    view.child = Some(child.clone().into_any());
5704                    cx.notify();
5705                });
5706                child
5707            })
5708            .unwrap();
5709
5710        actions.borrow_mut().clear();
5711        cx.update_window(window_id, |cx| {
5712            cx.dispatch_action(Some(view_4.id()), &Action("bar".to_string()))
5713        });
5714
5715        assert_eq!(
5716            *actions.borrow(),
5717            vec![
5718                "3 capture",
5719                "4 d",
5720                "4 c",
5721                "3 b",
5722                "3 a",
5723                "2 d",
5724                "2 c",
5725                "global"
5726            ]
5727        );
5728        assert_eq!(
5729            *observed_actions.borrow(),
5730            [Action::default().id(), Action::default().id()]
5731        );
5732    }
5733
5734    #[crate::test(self)]
5735    fn test_dispatch_keystroke(cx: &mut AppContext) {
5736        #[derive(Clone, Deserialize, PartialEq)]
5737        pub struct Action(String);
5738
5739        impl_actions!(test, [Action]);
5740
5741        struct View {
5742            id: usize,
5743            keymap_context: KeymapContext,
5744            child: Option<AnyViewHandle>,
5745        }
5746
5747        impl Entity for View {
5748            type Event = ();
5749        }
5750
5751        impl super::View for View {
5752            fn render(&mut self, cx: &mut ViewContext<Self>) -> AnyElement<Self> {
5753                self.child
5754                    .as_ref()
5755                    .map(|child| ChildView::new(child, cx).into_any())
5756                    .unwrap_or(Empty::new().into_any())
5757            }
5758
5759            fn ui_name() -> &'static str {
5760                "View"
5761            }
5762
5763            fn update_keymap_context(&self, keymap: &mut KeymapContext, _: &AppContext) {
5764                *keymap = self.keymap_context.clone();
5765            }
5766        }
5767
5768        impl View {
5769            fn new(id: usize) -> Self {
5770                View {
5771                    id,
5772                    keymap_context: KeymapContext::default(),
5773                    child: None,
5774                }
5775            }
5776        }
5777
5778        let mut view_1 = View::new(1);
5779        let mut view_2 = View::new(2);
5780        let mut view_3 = View::new(3);
5781        view_1.keymap_context.add_identifier("a");
5782        view_2.keymap_context.add_identifier("a");
5783        view_2.keymap_context.add_identifier("b");
5784        view_3.keymap_context.add_identifier("a");
5785        view_3.keymap_context.add_identifier("b");
5786        view_3.keymap_context.add_identifier("c");
5787
5788        let (window_id, _view_1) = cx.add_window(Default::default(), |cx| {
5789            let view_2 = cx.add_view(|cx| {
5790                let view_3 = cx.add_view(|cx| {
5791                    cx.focus_self();
5792                    view_3
5793                });
5794                view_2.child = Some(view_3.into_any());
5795                view_2
5796            });
5797            view_1.child = Some(view_2.into_any());
5798            view_1
5799        });
5800
5801        // This binding only dispatches an action on view 2 because that view will have
5802        // "a" and "b" in its context, but not "c".
5803        cx.add_bindings(vec![Binding::new(
5804            "a",
5805            Action("a".to_string()),
5806            Some("a && b && !c"),
5807        )]);
5808
5809        cx.add_bindings(vec![Binding::new("b", Action("b".to_string()), None)]);
5810
5811        // This binding only dispatches an action on views 2 and 3, because they have
5812        // a parent view with a in its context
5813        cx.add_bindings(vec![Binding::new(
5814            "c",
5815            Action("c".to_string()),
5816            Some("b > c"),
5817        )]);
5818
5819        // This binding only dispatches an action on view 2, because they have
5820        // a parent view with a in its context
5821        cx.add_bindings(vec![Binding::new(
5822            "d",
5823            Action("d".to_string()),
5824            Some("a && !b > b"),
5825        )]);
5826
5827        let actions = Rc::new(RefCell::new(Vec::new()));
5828        cx.add_action({
5829            let actions = actions.clone();
5830            move |view: &mut View, action: &Action, cx| {
5831                actions
5832                    .borrow_mut()
5833                    .push(format!("{} {}", view.id, action.0));
5834
5835                if action.0 == "b" {
5836                    cx.propagate_action();
5837                }
5838            }
5839        });
5840
5841        cx.add_global_action({
5842            let actions = actions.clone();
5843            move |action: &Action, _| {
5844                actions.borrow_mut().push(format!("global {}", action.0));
5845            }
5846        });
5847
5848        cx.update_window(window_id, |cx| {
5849            cx.dispatch_keystroke(&Keystroke::parse("a").unwrap())
5850        });
5851        assert_eq!(&*actions.borrow(), &["2 a"]);
5852        actions.borrow_mut().clear();
5853
5854        cx.update_window(window_id, |cx| {
5855            cx.dispatch_keystroke(&Keystroke::parse("b").unwrap());
5856        });
5857
5858        assert_eq!(&*actions.borrow(), &["3 b", "2 b", "1 b", "global b"]);
5859        actions.borrow_mut().clear();
5860
5861        cx.update_window(window_id, |cx| {
5862            cx.dispatch_keystroke(&Keystroke::parse("c").unwrap());
5863        });
5864        assert_eq!(&*actions.borrow(), &["3 c"]);
5865        actions.borrow_mut().clear();
5866
5867        cx.update_window(window_id, |cx| {
5868            cx.dispatch_keystroke(&Keystroke::parse("d").unwrap());
5869        });
5870        assert_eq!(&*actions.borrow(), &["2 d"]);
5871        actions.borrow_mut().clear();
5872    }
5873
5874    #[crate::test(self)]
5875    fn test_keystrokes_for_action(cx: &mut TestAppContext) {
5876        actions!(test, [Action1, Action2, GlobalAction]);
5877
5878        struct View1 {
5879            child: ViewHandle<View2>,
5880        }
5881        struct View2 {}
5882
5883        impl Entity for View1 {
5884            type Event = ();
5885        }
5886        impl Entity for View2 {
5887            type Event = ();
5888        }
5889
5890        impl super::View for View1 {
5891            fn render(&mut self, cx: &mut ViewContext<Self>) -> AnyElement<Self> {
5892                ChildView::new(&self.child, cx).into_any()
5893            }
5894            fn ui_name() -> &'static str {
5895                "View1"
5896            }
5897        }
5898        impl super::View for View2 {
5899            fn render(&mut self, _: &mut ViewContext<Self>) -> AnyElement<Self> {
5900                Empty::new().into_any()
5901            }
5902            fn ui_name() -> &'static str {
5903                "View2"
5904            }
5905        }
5906
5907        let (window_id, view_1) = cx.add_window(|cx| {
5908            let view_2 = cx.add_view(|cx| {
5909                cx.focus_self();
5910                View2 {}
5911            });
5912            View1 { child: view_2 }
5913        });
5914        let view_2 = view_1.read_with(cx, |view, _| view.child.clone());
5915
5916        cx.update(|cx| {
5917            cx.add_action(|_: &mut View1, _: &Action1, _cx| {});
5918            cx.add_action(|_: &mut View2, _: &Action2, _cx| {});
5919            cx.add_global_action(|_: &GlobalAction, _| {});
5920            cx.add_bindings(vec![
5921                Binding::new("a", Action1, Some("View1")),
5922                Binding::new("b", Action2, Some("View1 > View2")),
5923                Binding::new("c", GlobalAction, Some("View3")), // View 3 does not exist
5924            ]);
5925        });
5926
5927        let view_1_id = view_1.id();
5928        view_1.update(cx, |_, cx| {
5929            view_2.update(cx, |_, cx| {
5930                // Sanity check
5931                let mut new_parents = Default::default();
5932                let mut notify_views_if_parents_change = Default::default();
5933                let mut layout_cx = LayoutContext::new(
5934                    cx,
5935                    &mut new_parents,
5936                    &mut notify_views_if_parents_change,
5937                    false,
5938                );
5939                assert_eq!(
5940                    layout_cx
5941                        .keystrokes_for_action(view_1_id, &Action1)
5942                        .unwrap()
5943                        .as_slice(),
5944                    &[Keystroke::parse("a").unwrap()]
5945                );
5946                assert_eq!(
5947                    layout_cx
5948                        .keystrokes_for_action(view_2.id(), &Action2)
5949                        .unwrap()
5950                        .as_slice(),
5951                    &[Keystroke::parse("b").unwrap()]
5952                );
5953
5954                // The 'a' keystroke propagates up the view tree from view_2
5955                // to view_1. The action, Action1, is handled by view_1.
5956                assert_eq!(
5957                    layout_cx
5958                        .keystrokes_for_action(view_2.id(), &Action1)
5959                        .unwrap()
5960                        .as_slice(),
5961                    &[Keystroke::parse("a").unwrap()]
5962                );
5963
5964                // Actions that are handled below the current view don't have bindings
5965                assert_eq!(layout_cx.keystrokes_for_action(view_1_id, &Action2), None);
5966
5967                // Actions that are handled in other branches of the tree should not have a binding
5968                assert_eq!(
5969                    layout_cx.keystrokes_for_action(view_2.id(), &GlobalAction),
5970                    None
5971                );
5972            });
5973        });
5974
5975        // Check that global actions do not have a binding, even if a binding does exist in another view
5976        assert_eq!(
5977            &available_actions(window_id, view_1.id(), cx),
5978            &[
5979                ("test::Action1", vec![Keystroke::parse("a").unwrap()]),
5980                ("test::GlobalAction", vec![])
5981            ],
5982        );
5983
5984        // Check that view 1 actions and bindings are available even when called from view 2
5985        assert_eq!(
5986            &available_actions(window_id, view_2.id(), cx),
5987            &[
5988                ("test::Action1", vec![Keystroke::parse("a").unwrap()]),
5989                ("test::Action2", vec![Keystroke::parse("b").unwrap()]),
5990                ("test::GlobalAction", vec![]),
5991            ],
5992        );
5993
5994        // Produces a list of actions and key bindings
5995        fn available_actions(
5996            window_id: usize,
5997            view_id: usize,
5998            cx: &TestAppContext,
5999        ) -> Vec<(&'static str, Vec<Keystroke>)> {
6000            cx.available_actions(window_id, view_id)
6001                .into_iter()
6002                .map(|(action_name, _, bindings)| {
6003                    (
6004                        action_name,
6005                        bindings
6006                            .iter()
6007                            .map(|binding| binding.keystrokes()[0].clone())
6008                            .collect::<Vec<_>>(),
6009                    )
6010                })
6011                .sorted_by(|(name1, _), (name2, _)| name1.cmp(name2))
6012                .collect()
6013        }
6014    }
6015
6016    #[crate::test(self)]
6017    async fn test_model_condition(cx: &mut TestAppContext) {
6018        struct Counter(usize);
6019
6020        impl super::Entity for Counter {
6021            type Event = ();
6022        }
6023
6024        impl Counter {
6025            fn inc(&mut self, cx: &mut ModelContext<Self>) {
6026                self.0 += 1;
6027                cx.notify();
6028            }
6029        }
6030
6031        let model = cx.add_model(|_| Counter(0));
6032
6033        let condition1 = model.condition(cx, |model, _| model.0 == 2);
6034        let condition2 = model.condition(cx, |model, _| model.0 == 3);
6035        smol::pin!(condition1, condition2);
6036
6037        model.update(cx, |model, cx| model.inc(cx));
6038        assert_eq!(poll_once(&mut condition1).await, None);
6039        assert_eq!(poll_once(&mut condition2).await, None);
6040
6041        model.update(cx, |model, cx| model.inc(cx));
6042        assert_eq!(poll_once(&mut condition1).await, Some(()));
6043        assert_eq!(poll_once(&mut condition2).await, None);
6044
6045        model.update(cx, |model, cx| model.inc(cx));
6046        assert_eq!(poll_once(&mut condition2).await, Some(()));
6047
6048        model.update(cx, |_, cx| cx.notify());
6049    }
6050
6051    #[crate::test(self)]
6052    #[should_panic]
6053    async fn test_model_condition_timeout(cx: &mut TestAppContext) {
6054        struct Model;
6055
6056        impl super::Entity for Model {
6057            type Event = ();
6058        }
6059
6060        let model = cx.add_model(|_| Model);
6061        model.condition(cx, |_, _| false).await;
6062    }
6063
6064    #[crate::test(self)]
6065    #[should_panic(expected = "model dropped with pending condition")]
6066    async fn test_model_condition_panic_on_drop(cx: &mut TestAppContext) {
6067        struct Model;
6068
6069        impl super::Entity for Model {
6070            type Event = ();
6071        }
6072
6073        let model = cx.add_model(|_| Model);
6074        let condition = model.condition(cx, |_, _| false);
6075        cx.update(|_| drop(model));
6076        condition.await;
6077    }
6078
6079    #[crate::test(self)]
6080    async fn test_view_condition(cx: &mut TestAppContext) {
6081        struct Counter(usize);
6082
6083        impl super::Entity for Counter {
6084            type Event = ();
6085        }
6086
6087        impl super::View for Counter {
6088            fn ui_name() -> &'static str {
6089                "test view"
6090            }
6091
6092            fn render(&mut self, _: &mut ViewContext<Self>) -> AnyElement<Self> {
6093                Empty::new().into_any()
6094            }
6095        }
6096
6097        impl Counter {
6098            fn inc(&mut self, cx: &mut ViewContext<Self>) {
6099                self.0 += 1;
6100                cx.notify();
6101            }
6102        }
6103
6104        let (_, view) = cx.add_window(|_| Counter(0));
6105
6106        let condition1 = view.condition(cx, |view, _| view.0 == 2);
6107        let condition2 = view.condition(cx, |view, _| view.0 == 3);
6108        smol::pin!(condition1, condition2);
6109
6110        view.update(cx, |view, cx| view.inc(cx));
6111        assert_eq!(poll_once(&mut condition1).await, None);
6112        assert_eq!(poll_once(&mut condition2).await, None);
6113
6114        view.update(cx, |view, cx| view.inc(cx));
6115        assert_eq!(poll_once(&mut condition1).await, Some(()));
6116        assert_eq!(poll_once(&mut condition2).await, None);
6117
6118        view.update(cx, |view, cx| view.inc(cx));
6119        assert_eq!(poll_once(&mut condition2).await, Some(()));
6120        view.update(cx, |_, cx| cx.notify());
6121    }
6122
6123    #[crate::test(self)]
6124    #[should_panic]
6125    async fn test_view_condition_timeout(cx: &mut TestAppContext) {
6126        let (_, view) = cx.add_window(|_| TestView::default());
6127        view.condition(cx, |_, _| false).await;
6128    }
6129
6130    #[crate::test(self)]
6131    #[should_panic(expected = "view dropped with pending condition")]
6132    async fn test_view_condition_panic_on_drop(cx: &mut TestAppContext) {
6133        let (window_id, _root_view) = cx.add_window(|_| TestView::default());
6134        let view = cx.add_view(window_id, |_| TestView::default());
6135
6136        let condition = view.condition(cx, |_, _| false);
6137        cx.update(|_| drop(view));
6138        condition.await;
6139    }
6140
6141    #[crate::test(self)]
6142    fn test_refresh_windows(cx: &mut AppContext) {
6143        struct View(usize);
6144
6145        impl super::Entity for View {
6146            type Event = ();
6147        }
6148
6149        impl super::View for View {
6150            fn ui_name() -> &'static str {
6151                "test view"
6152            }
6153
6154            fn render(&mut self, _: &mut ViewContext<Self>) -> AnyElement<Self> {
6155                Empty::new().into_any_named(format!("render count: {}", post_inc(&mut self.0)))
6156            }
6157        }
6158
6159        let (window_id, root_view) = cx.add_window(Default::default(), |_| View(0));
6160        cx.update_window(window_id, |cx| {
6161            assert_eq!(
6162                cx.window.rendered_views[&root_view.id()].name(),
6163                Some("render count: 0")
6164            );
6165        });
6166
6167        let view = cx
6168            .update_window(window_id, |cx| {
6169                cx.refresh_windows();
6170                cx.add_view(|_| View(0))
6171            })
6172            .unwrap();
6173
6174        cx.update_window(window_id, |cx| {
6175            assert_eq!(
6176                cx.window.rendered_views[&root_view.id()].name(),
6177                Some("render count: 1")
6178            );
6179            assert_eq!(
6180                cx.window.rendered_views[&view.id()].name(),
6181                Some("render count: 0")
6182            );
6183        });
6184
6185        cx.update(|cx| cx.refresh_windows());
6186
6187        cx.update_window(window_id, |cx| {
6188            assert_eq!(
6189                cx.window.rendered_views[&root_view.id()].name(),
6190                Some("render count: 2")
6191            );
6192            assert_eq!(
6193                cx.window.rendered_views[&view.id()].name(),
6194                Some("render count: 1")
6195            );
6196        });
6197
6198        cx.update(|cx| {
6199            cx.refresh_windows();
6200            drop(view);
6201        });
6202
6203        cx.update_window(window_id, |cx| {
6204            assert_eq!(
6205                cx.window.rendered_views[&root_view.id()].name(),
6206                Some("render count: 3")
6207            );
6208            assert_eq!(cx.window.rendered_views.len(), 1);
6209        });
6210    }
6211
6212    #[crate::test(self)]
6213    async fn test_labeled_tasks(cx: &mut TestAppContext) {
6214        assert_eq!(None, cx.update(|cx| cx.active_labeled_tasks().next()));
6215        let (mut sender, mut reciever) = postage::oneshot::channel::<()>();
6216        let task = cx
6217            .update(|cx| cx.spawn_labeled("Test Label", |_| async move { reciever.recv().await }));
6218
6219        assert_eq!(
6220            Some("Test Label"),
6221            cx.update(|cx| cx.active_labeled_tasks().next())
6222        );
6223        sender
6224            .send(())
6225            .await
6226            .expect("Could not send message to complete task");
6227        task.await;
6228
6229        assert_eq!(None, cx.update(|cx| cx.active_labeled_tasks().next()));
6230    }
6231
6232    #[crate::test(self)]
6233    async fn test_window_activation(cx: &mut TestAppContext) {
6234        struct View(&'static str);
6235
6236        impl super::Entity for View {
6237            type Event = ();
6238        }
6239
6240        impl super::View for View {
6241            fn ui_name() -> &'static str {
6242                "test view"
6243            }
6244
6245            fn render(&mut self, _: &mut ViewContext<Self>) -> AnyElement<Self> {
6246                Empty::new().into_any()
6247            }
6248        }
6249
6250        let events = Rc::new(RefCell::new(Vec::new()));
6251        let (window_1, _) = cx.add_window(|cx: &mut ViewContext<View>| {
6252            cx.observe_window_activation({
6253                let events = events.clone();
6254                move |this, active, _| events.borrow_mut().push((this.0, active))
6255            })
6256            .detach();
6257            View("window 1")
6258        });
6259        assert_eq!(mem::take(&mut *events.borrow_mut()), [("window 1", true)]);
6260
6261        let (window_2, _) = cx.add_window(|cx: &mut ViewContext<View>| {
6262            cx.observe_window_activation({
6263                let events = events.clone();
6264                move |this, active, _| events.borrow_mut().push((this.0, active))
6265            })
6266            .detach();
6267            View("window 2")
6268        });
6269        assert_eq!(
6270            mem::take(&mut *events.borrow_mut()),
6271            [("window 1", false), ("window 2", true)]
6272        );
6273
6274        let (window_3, _) = cx.add_window(|cx: &mut ViewContext<View>| {
6275            cx.observe_window_activation({
6276                let events = events.clone();
6277                move |this, active, _| events.borrow_mut().push((this.0, active))
6278            })
6279            .detach();
6280            View("window 3")
6281        });
6282        assert_eq!(
6283            mem::take(&mut *events.borrow_mut()),
6284            [("window 2", false), ("window 3", true)]
6285        );
6286
6287        cx.simulate_window_activation(Some(window_2));
6288        assert_eq!(
6289            mem::take(&mut *events.borrow_mut()),
6290            [("window 3", false), ("window 2", true)]
6291        );
6292
6293        cx.simulate_window_activation(Some(window_1));
6294        assert_eq!(
6295            mem::take(&mut *events.borrow_mut()),
6296            [("window 2", false), ("window 1", true)]
6297        );
6298
6299        cx.simulate_window_activation(Some(window_3));
6300        assert_eq!(
6301            mem::take(&mut *events.borrow_mut()),
6302            [("window 1", false), ("window 3", true)]
6303        );
6304
6305        cx.simulate_window_activation(Some(window_3));
6306        assert_eq!(mem::take(&mut *events.borrow_mut()), []);
6307    }
6308
6309    #[crate::test(self)]
6310    fn test_child_view(cx: &mut TestAppContext) {
6311        struct Child {
6312            rendered: Rc<Cell<bool>>,
6313            dropped: Rc<Cell<bool>>,
6314        }
6315
6316        impl super::Entity for Child {
6317            type Event = ();
6318        }
6319
6320        impl super::View for Child {
6321            fn ui_name() -> &'static str {
6322                "child view"
6323            }
6324
6325            fn render(&mut self, _: &mut ViewContext<Self>) -> AnyElement<Self> {
6326                self.rendered.set(true);
6327                Empty::new().into_any()
6328            }
6329        }
6330
6331        impl Drop for Child {
6332            fn drop(&mut self) {
6333                self.dropped.set(true);
6334            }
6335        }
6336
6337        struct Parent {
6338            child: Option<ViewHandle<Child>>,
6339        }
6340
6341        impl super::Entity for Parent {
6342            type Event = ();
6343        }
6344
6345        impl super::View for Parent {
6346            fn ui_name() -> &'static str {
6347                "parent view"
6348            }
6349
6350            fn render(&mut self, cx: &mut ViewContext<Self>) -> AnyElement<Self> {
6351                if let Some(child) = self.child.as_ref() {
6352                    ChildView::new(child, cx).into_any()
6353                } else {
6354                    Empty::new().into_any()
6355                }
6356            }
6357        }
6358
6359        let child_rendered = Rc::new(Cell::new(false));
6360        let child_dropped = Rc::new(Cell::new(false));
6361        let (_, root_view) = cx.add_window(|cx| Parent {
6362            child: Some(cx.add_view(|_| Child {
6363                rendered: child_rendered.clone(),
6364                dropped: child_dropped.clone(),
6365            })),
6366        });
6367        assert!(child_rendered.take());
6368        assert!(!child_dropped.take());
6369
6370        root_view.update(cx, |view, cx| {
6371            view.child.take();
6372            cx.notify();
6373        });
6374        assert!(!child_rendered.take());
6375        assert!(child_dropped.take());
6376    }
6377
6378    #[derive(Default)]
6379    struct TestView {
6380        events: Vec<String>,
6381    }
6382
6383    impl Entity for TestView {
6384        type Event = String;
6385    }
6386
6387    impl View for TestView {
6388        fn ui_name() -> &'static str {
6389            "TestView"
6390        }
6391
6392        fn render(&mut self, _: &mut ViewContext<Self>) -> AnyElement<Self> {
6393            Empty::new().into_any()
6394        }
6395    }
6396}