app.rs

   1use crate::{
   2    elements::ElementBox,
   3    executor,
   4    keymap::{self, Keystroke},
   5    platform::{self, WindowOptions},
   6    presenter::Presenter,
   7    util::{post_inc, timeout},
   8    AssetCache, AssetSource, ClipboardItem, FontCache, PathPromptOptions, TextLayoutCache,
   9};
  10use anyhow::{anyhow, Result};
  11use async_task::Task;
  12use keymap::MatchResult;
  13use parking_lot::{Mutex, RwLock};
  14use pathfinder_geometry::{rect::RectF, vector::vec2f};
  15use platform::Event;
  16use postage::{mpsc, sink::Sink as _, stream::Stream as _};
  17use smol::prelude::*;
  18use std::{
  19    any::{type_name, Any, TypeId},
  20    cell::RefCell,
  21    collections::{hash_map::Entry, HashMap, HashSet, VecDeque},
  22    fmt::{self, Debug},
  23    hash::{Hash, Hasher},
  24    marker::PhantomData,
  25    path::{Path, PathBuf},
  26    rc::{self, Rc},
  27    sync::{Arc, Weak},
  28    time::Duration,
  29};
  30
  31pub trait Entity: 'static + Send + Sync {
  32    type Event;
  33}
  34
  35pub trait View: Entity {
  36    fn ui_name() -> &'static str;
  37    fn render<'a>(&self, app: &AppContext) -> ElementBox;
  38    fn on_focus(&mut self, _ctx: &mut ViewContext<Self>) {}
  39    fn on_blur(&mut self, _ctx: &mut ViewContext<Self>) {}
  40    fn keymap_context(&self, _: &AppContext) -> keymap::Context {
  41        Self::default_keymap_context()
  42    }
  43    fn default_keymap_context() -> keymap::Context {
  44        let mut ctx = keymap::Context::default();
  45        ctx.set.insert(Self::ui_name().into());
  46        ctx
  47    }
  48}
  49
  50pub trait ReadModel {
  51    fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T;
  52}
  53
  54pub trait ReadModelWith {
  55    fn read_model_with<E: Entity, F: FnOnce(&E, &AppContext) -> T, T>(
  56        &self,
  57        handle: &ModelHandle<E>,
  58        read: F,
  59    ) -> T;
  60}
  61
  62pub trait UpdateModel {
  63    fn update_model<T, F, S>(&mut self, handle: &ModelHandle<T>, update: F) -> S
  64    where
  65        T: Entity,
  66        F: FnOnce(&mut T, &mut ModelContext<T>) -> S;
  67}
  68
  69pub trait ReadView {
  70    fn read_view<T: View>(&self, handle: &ViewHandle<T>) -> &T;
  71}
  72
  73pub trait ReadViewWith {
  74    fn read_view_with<V, F, T>(&self, handle: &ViewHandle<V>, read: F) -> T
  75    where
  76        V: View,
  77        F: FnOnce(&V, &AppContext) -> T;
  78}
  79
  80pub trait UpdateView {
  81    fn update_view<T, F, S>(&mut self, handle: &ViewHandle<T>, update: F) -> S
  82    where
  83        T: View,
  84        F: FnOnce(&mut T, &mut ViewContext<T>) -> S;
  85}
  86
  87pub struct Menu<'a> {
  88    pub name: &'a str,
  89    pub items: Vec<MenuItem<'a>>,
  90}
  91
  92pub enum MenuItem<'a> {
  93    Action {
  94        name: &'a str,
  95        keystroke: Option<&'a str>,
  96        action: &'a str,
  97        arg: Option<Box<dyn Any + 'static>>,
  98    },
  99    Separator,
 100}
 101
 102#[derive(Clone)]
 103pub struct App(Rc<RefCell<MutableAppContext>>);
 104
 105pub struct AsyncAppContext(Rc<RefCell<MutableAppContext>>);
 106
 107#[derive(Clone)]
 108pub struct TestAppContext(Rc<RefCell<MutableAppContext>>, Rc<platform::test::Platform>);
 109
 110impl App {
 111    pub fn test<T, A: AssetSource, F: FnOnce(&mut MutableAppContext) -> T>(
 112        asset_source: A,
 113        f: F,
 114    ) -> T {
 115        let platform = platform::test::platform();
 116        let foreground = Rc::new(executor::Foreground::test());
 117        let ctx = Rc::new(RefCell::new(MutableAppContext::new(
 118            foreground,
 119            Rc::new(platform),
 120            asset_source,
 121        )));
 122        ctx.borrow_mut().weak_self = Some(Rc::downgrade(&ctx));
 123        let mut ctx = ctx.borrow_mut();
 124        f(&mut *ctx)
 125    }
 126
 127    pub fn test_async<T, F, A: AssetSource, Fn>(asset_source: A, f: Fn) -> T
 128    where
 129        Fn: FnOnce(TestAppContext) -> F,
 130        F: Future<Output = T>,
 131    {
 132        let platform = Rc::new(platform::test::platform());
 133        let foreground = Rc::new(executor::Foreground::test());
 134        let ctx = TestAppContext(
 135            Rc::new(RefCell::new(MutableAppContext::new(
 136                foreground.clone(),
 137                platform.clone(),
 138                asset_source,
 139            ))),
 140            platform,
 141        );
 142        ctx.0.borrow_mut().weak_self = Some(Rc::downgrade(&ctx.0));
 143
 144        let future = f(ctx);
 145        smol::block_on(foreground.run(future))
 146    }
 147
 148    pub fn new(asset_source: impl AssetSource) -> Result<Self> {
 149        let platform = platform::current::platform();
 150        let foreground = Rc::new(executor::Foreground::platform(platform.dispatcher())?);
 151        let app = Self(Rc::new(RefCell::new(MutableAppContext::new(
 152            foreground,
 153            platform.clone(),
 154            asset_source,
 155        ))));
 156
 157        let ctx = app.0.clone();
 158        platform.on_menu_command(Box::new(move |command, arg| {
 159            let mut ctx = ctx.borrow_mut();
 160            if let Some(key_window_id) = ctx.platform.key_window_id() {
 161                if let Some((presenter, _)) =
 162                    ctx.presenters_and_platform_windows.get(&key_window_id)
 163                {
 164                    let presenter = presenter.clone();
 165                    let path = presenter.borrow().dispatch_path(ctx.as_ref());
 166                    ctx.dispatch_action_any(key_window_id, &path, command, arg.unwrap_or(&()));
 167                } else {
 168                    ctx.dispatch_global_action_any(command, arg.unwrap_or(&()));
 169                }
 170            } else {
 171                ctx.dispatch_global_action_any(command, arg.unwrap_or(&()));
 172            }
 173        }));
 174
 175        app.0.borrow_mut().weak_self = Some(Rc::downgrade(&app.0));
 176        Ok(app)
 177    }
 178
 179    pub fn on_become_active<F>(self, mut callback: F) -> Self
 180    where
 181        F: 'static + FnMut(&mut MutableAppContext),
 182    {
 183        let ctx = self.0.clone();
 184        self.0
 185            .borrow()
 186            .platform
 187            .on_become_active(Box::new(move || callback(&mut *ctx.borrow_mut())));
 188        self
 189    }
 190
 191    pub fn on_resign_active<F>(self, mut callback: F) -> Self
 192    where
 193        F: 'static + FnMut(&mut MutableAppContext),
 194    {
 195        let ctx = self.0.clone();
 196        self.0
 197            .borrow()
 198            .platform
 199            .on_resign_active(Box::new(move || callback(&mut *ctx.borrow_mut())));
 200        self
 201    }
 202
 203    pub fn on_event<F>(self, mut callback: F) -> Self
 204    where
 205        F: 'static + FnMut(Event, &mut MutableAppContext) -> bool,
 206    {
 207        let ctx = self.0.clone();
 208        self.0.borrow().platform.on_event(Box::new(move |event| {
 209            callback(event, &mut *ctx.borrow_mut())
 210        }));
 211        self
 212    }
 213
 214    pub fn on_open_files<F>(self, mut callback: F) -> Self
 215    where
 216        F: 'static + FnMut(Vec<PathBuf>, &mut MutableAppContext),
 217    {
 218        let ctx = self.0.clone();
 219        self.0
 220            .borrow()
 221            .platform
 222            .on_open_files(Box::new(move |paths| {
 223                callback(paths, &mut *ctx.borrow_mut())
 224            }));
 225        self
 226    }
 227
 228    pub fn run<F>(self, on_finish_launching: F)
 229    where
 230        F: 'static + FnOnce(&mut MutableAppContext),
 231    {
 232        let platform = self.0.borrow().platform.clone();
 233        platform.run(Box::new(move || {
 234            let mut ctx = self.0.borrow_mut();
 235            on_finish_launching(&mut *ctx);
 236        }))
 237    }
 238
 239    pub fn font_cache(&self) -> Arc<FontCache> {
 240        self.0.borrow().ctx.font_cache.clone()
 241    }
 242
 243    fn update<T, F: FnOnce(&mut MutableAppContext) -> T>(&mut self, callback: F) -> T {
 244        let mut state = self.0.borrow_mut();
 245        state.pending_flushes += 1;
 246        let result = callback(&mut *state);
 247        state.flush_effects();
 248        result
 249    }
 250}
 251
 252impl TestAppContext {
 253    pub fn dispatch_action<T: 'static + Any>(
 254        &self,
 255        window_id: usize,
 256        responder_chain: Vec<usize>,
 257        name: &str,
 258        arg: T,
 259    ) {
 260        self.0.borrow_mut().dispatch_action_any(
 261            window_id,
 262            &responder_chain,
 263            name,
 264            Box::new(arg).as_ref(),
 265        );
 266    }
 267
 268    pub fn dispatch_keystroke(
 269        &self,
 270        window_id: usize,
 271        responder_chain: Vec<usize>,
 272        keystroke: &Keystroke,
 273    ) -> Result<bool> {
 274        let mut state = self.0.borrow_mut();
 275        state.dispatch_keystroke(window_id, responder_chain, keystroke)
 276    }
 277
 278    pub fn add_model<T, F>(&mut self, build_model: F) -> ModelHandle<T>
 279    where
 280        T: Entity,
 281        F: FnOnce(&mut ModelContext<T>) -> T,
 282    {
 283        let mut state = self.0.borrow_mut();
 284        state.pending_flushes += 1;
 285        let handle = state.add_model(build_model);
 286        state.flush_effects();
 287        handle
 288    }
 289
 290    pub fn add_window<T, F>(&mut self, build_root_view: F) -> (usize, ViewHandle<T>)
 291    where
 292        T: View,
 293        F: FnOnce(&mut ViewContext<T>) -> T,
 294    {
 295        self.0.borrow_mut().add_window(build_root_view)
 296    }
 297
 298    pub fn window_ids(&self) -> Vec<usize> {
 299        self.0.borrow().window_ids().collect()
 300    }
 301
 302    pub fn root_view<T: View>(&self, window_id: usize) -> Option<ViewHandle<T>> {
 303        self.0.borrow().root_view(window_id)
 304    }
 305
 306    pub fn add_view<T, F>(&mut self, window_id: usize, build_view: F) -> ViewHandle<T>
 307    where
 308        T: View,
 309        F: FnOnce(&mut ViewContext<T>) -> T,
 310    {
 311        let mut state = self.0.borrow_mut();
 312        state.pending_flushes += 1;
 313        let handle = state.add_view(window_id, build_view);
 314        state.flush_effects();
 315        handle
 316    }
 317
 318    pub fn add_option_view<T, F>(
 319        &mut self,
 320        window_id: usize,
 321        build_view: F,
 322    ) -> Option<ViewHandle<T>>
 323    where
 324        T: View,
 325        F: FnOnce(&mut ViewContext<T>) -> Option<T>,
 326    {
 327        let mut state = self.0.borrow_mut();
 328        state.pending_flushes += 1;
 329        let handle = state.add_option_view(window_id, build_view);
 330        state.flush_effects();
 331        handle
 332    }
 333
 334    pub fn read<T, F: FnOnce(&AppContext) -> T>(&self, callback: F) -> T {
 335        callback(self.0.borrow().as_ref())
 336    }
 337
 338    pub fn update<T, F: FnOnce(&mut MutableAppContext) -> T>(&mut self, callback: F) -> T {
 339        let mut state = self.0.borrow_mut();
 340        // Don't increment pending flushes in order to effects to be flushed before the callback
 341        // completes, which is helpful in tests.
 342        let result = callback(&mut *state);
 343        // Flush effects after the callback just in case there are any. This can happen in edge
 344        // cases such as the closure dropping handles.
 345        state.flush_effects();
 346        result
 347    }
 348
 349    pub fn font_cache(&self) -> Arc<FontCache> {
 350        self.0.borrow().ctx.font_cache.clone()
 351    }
 352
 353    pub fn platform(&self) -> Rc<dyn platform::Platform> {
 354        self.0.borrow().platform.clone()
 355    }
 356
 357    pub fn simulate_new_path_selection(&self, result: impl FnOnce(PathBuf) -> Option<PathBuf>) {
 358        self.1.as_ref().simulate_new_path_selection(result);
 359    }
 360
 361    pub fn did_prompt_for_new_path(&self) -> bool {
 362        self.1.as_ref().did_prompt_for_new_path()
 363    }
 364}
 365
 366impl AsyncAppContext {
 367    pub fn read<T, F: FnOnce(&AppContext) -> T>(&mut self, callback: F) -> T {
 368        callback(self.0.borrow().as_ref())
 369    }
 370
 371    pub fn update<T, F: FnOnce(&mut MutableAppContext) -> T>(&mut self, callback: F) -> T {
 372        let mut state = self.0.borrow_mut();
 373        state.pending_flushes += 1;
 374        let result = callback(&mut *state);
 375        state.flush_effects();
 376        result
 377    }
 378
 379    pub fn add_model<T, F>(&mut self, build_model: F) -> ModelHandle<T>
 380    where
 381        T: Entity,
 382        F: FnOnce(&mut ModelContext<T>) -> T,
 383    {
 384        self.update(|ctx| ctx.add_model(build_model))
 385    }
 386}
 387
 388impl UpdateModel for AsyncAppContext {
 389    fn update_model<T, F, S>(&mut self, handle: &ModelHandle<T>, update: F) -> S
 390    where
 391        T: Entity,
 392        F: FnOnce(&mut T, &mut ModelContext<T>) -> S,
 393    {
 394        let mut state = self.0.borrow_mut();
 395        state.pending_flushes += 1;
 396        let result = state.update_model(handle, update);
 397        state.flush_effects();
 398        result
 399    }
 400}
 401
 402impl ReadModelWith for AsyncAppContext {
 403    fn read_model_with<E: Entity, F: FnOnce(&E, &AppContext) -> T, T>(
 404        &self,
 405        handle: &ModelHandle<E>,
 406        read: F,
 407    ) -> T {
 408        let ctx = self.0.borrow();
 409        let ctx = ctx.as_ref();
 410        read(handle.read(ctx), ctx)
 411    }
 412}
 413
 414impl UpdateView for AsyncAppContext {
 415    fn update_view<T, F, S>(&mut self, handle: &ViewHandle<T>, update: F) -> S
 416    where
 417        T: View,
 418        F: FnOnce(&mut T, &mut ViewContext<T>) -> S,
 419    {
 420        let mut state = self.0.borrow_mut();
 421        state.pending_flushes += 1;
 422        let result = state.update_view(handle, update);
 423        state.flush_effects();
 424        result
 425    }
 426}
 427
 428impl ReadViewWith for AsyncAppContext {
 429    fn read_view_with<V, F, T>(&self, handle: &ViewHandle<V>, read: F) -> T
 430    where
 431        V: View,
 432        F: FnOnce(&V, &AppContext) -> T,
 433    {
 434        let ctx = self.0.borrow();
 435        let ctx = ctx.as_ref();
 436        read(handle.read(ctx), ctx)
 437    }
 438}
 439
 440impl UpdateModel for TestAppContext {
 441    fn update_model<T, F, S>(&mut self, handle: &ModelHandle<T>, update: F) -> S
 442    where
 443        T: Entity,
 444        F: FnOnce(&mut T, &mut ModelContext<T>) -> S,
 445    {
 446        let mut state = self.0.borrow_mut();
 447        state.pending_flushes += 1;
 448        let result = state.update_model(handle, update);
 449        state.flush_effects();
 450        result
 451    }
 452}
 453
 454impl ReadModelWith for TestAppContext {
 455    fn read_model_with<E: Entity, F: FnOnce(&E, &AppContext) -> T, T>(
 456        &self,
 457        handle: &ModelHandle<E>,
 458        read: F,
 459    ) -> T {
 460        let ctx = self.0.borrow();
 461        let ctx = ctx.as_ref();
 462        read(handle.read(ctx), ctx)
 463    }
 464}
 465
 466impl UpdateView for TestAppContext {
 467    fn update_view<T, F, S>(&mut self, handle: &ViewHandle<T>, update: F) -> S
 468    where
 469        T: View,
 470        F: FnOnce(&mut T, &mut ViewContext<T>) -> S,
 471    {
 472        let mut state = self.0.borrow_mut();
 473        state.pending_flushes += 1;
 474        let result = state.update_view(handle, update);
 475        state.flush_effects();
 476        result
 477    }
 478}
 479
 480impl ReadViewWith for TestAppContext {
 481    fn read_view_with<V, F, T>(&self, handle: &ViewHandle<V>, read: F) -> T
 482    where
 483        V: View,
 484        F: FnOnce(&V, &AppContext) -> T,
 485    {
 486        let ctx = self.0.borrow();
 487        let ctx = ctx.as_ref();
 488        read(handle.read(ctx), ctx)
 489    }
 490}
 491
 492type ActionCallback =
 493    dyn FnMut(&mut dyn AnyView, &dyn Any, &mut MutableAppContext, usize, usize) -> bool;
 494
 495type GlobalActionCallback = dyn FnMut(&dyn Any, &mut MutableAppContext);
 496
 497pub struct MutableAppContext {
 498    weak_self: Option<rc::Weak<RefCell<Self>>>,
 499    platform: Rc<dyn platform::Platform>,
 500    assets: Arc<AssetCache>,
 501    ctx: AppContext,
 502    actions: HashMap<TypeId, HashMap<String, Vec<Box<ActionCallback>>>>,
 503    global_actions: HashMap<String, Vec<Box<GlobalActionCallback>>>,
 504    keystroke_matcher: keymap::Matcher,
 505    next_entity_id: usize,
 506    next_window_id: usize,
 507    subscriptions: HashMap<usize, Vec<Subscription>>,
 508    model_observations: HashMap<usize, Vec<ModelObservation>>,
 509    view_observations: HashMap<usize, Vec<ViewObservation>>,
 510    presenters_and_platform_windows:
 511        HashMap<usize, (Rc<RefCell<Presenter>>, Box<dyn platform::Window>)>,
 512    debug_elements_callbacks: HashMap<usize, Box<dyn Fn(&AppContext) -> crate::json::Value>>,
 513    foreground: Rc<executor::Foreground>,
 514    pending_effects: VecDeque<Effect>,
 515    pending_flushes: usize,
 516    flushing_effects: bool,
 517}
 518
 519impl MutableAppContext {
 520    pub fn new(
 521        foreground: Rc<executor::Foreground>,
 522        platform: Rc<dyn platform::Platform>,
 523        asset_source: impl AssetSource,
 524    ) -> Self {
 525        let fonts = platform.fonts();
 526        Self {
 527            weak_self: None,
 528            platform,
 529            assets: Arc::new(AssetCache::new(asset_source)),
 530            ctx: AppContext {
 531                models: Default::default(),
 532                views: Default::default(),
 533                windows: Default::default(),
 534                values: Default::default(),
 535                ref_counts: Arc::new(Mutex::new(RefCounts::default())),
 536                background: Arc::new(executor::Background::new()),
 537                thread_pool: scoped_pool::Pool::new(num_cpus::get(), "app"),
 538                font_cache: Arc::new(FontCache::new(fonts)),
 539            },
 540            actions: HashMap::new(),
 541            global_actions: HashMap::new(),
 542            keystroke_matcher: keymap::Matcher::default(),
 543            next_entity_id: 0,
 544            next_window_id: 0,
 545            subscriptions: HashMap::new(),
 546            model_observations: HashMap::new(),
 547            view_observations: HashMap::new(),
 548            presenters_and_platform_windows: HashMap::new(),
 549            debug_elements_callbacks: HashMap::new(),
 550            foreground,
 551            pending_effects: VecDeque::new(),
 552            pending_flushes: 0,
 553            flushing_effects: false,
 554        }
 555    }
 556
 557    pub fn upgrade(&self) -> App {
 558        App(self.weak_self.as_ref().unwrap().upgrade().unwrap())
 559    }
 560
 561    pub fn platform(&self) -> Rc<dyn platform::Platform> {
 562        self.platform.clone()
 563    }
 564
 565    pub fn font_cache(&self) -> &Arc<FontCache> {
 566        &self.ctx.font_cache
 567    }
 568
 569    pub fn foreground_executor(&self) -> &Rc<executor::Foreground> {
 570        &self.foreground
 571    }
 572
 573    pub fn background_executor(&self) -> &Arc<executor::Background> {
 574        &self.ctx.background
 575    }
 576
 577    pub fn on_debug_elements<F>(&mut self, window_id: usize, callback: F)
 578    where
 579        F: 'static + Fn(&AppContext) -> crate::json::Value,
 580    {
 581        self.debug_elements_callbacks
 582            .insert(window_id, Box::new(callback));
 583    }
 584
 585    pub fn debug_elements(&self, window_id: usize) -> Option<crate::json::Value> {
 586        self.debug_elements_callbacks
 587            .get(&window_id)
 588            .map(|debug_elements| debug_elements(&self.ctx))
 589    }
 590
 591    pub fn add_action<S, V, T, F>(&mut self, name: S, mut handler: F)
 592    where
 593        S: Into<String>,
 594        V: View,
 595        T: Any,
 596        F: 'static + FnMut(&mut V, &T, &mut ViewContext<V>),
 597    {
 598        let name = name.into();
 599        let name_clone = name.clone();
 600        let handler = Box::new(
 601            move |view: &mut dyn AnyView,
 602                  arg: &dyn Any,
 603                  app: &mut MutableAppContext,
 604                  window_id: usize,
 605                  view_id: usize| {
 606                match arg.downcast_ref() {
 607                    Some(arg) => {
 608                        let mut ctx = ViewContext::new(app, window_id, view_id);
 609                        handler(
 610                            view.as_any_mut()
 611                                .downcast_mut()
 612                                .expect("downcast is type safe"),
 613                            arg,
 614                            &mut ctx,
 615                        );
 616                        ctx.halt_action_dispatch
 617                    }
 618                    None => {
 619                        log::error!("Could not downcast argument for action {}", name_clone);
 620                        false
 621                    }
 622                }
 623            },
 624        );
 625
 626        self.actions
 627            .entry(TypeId::of::<V>())
 628            .or_default()
 629            .entry(name)
 630            .or_default()
 631            .push(handler);
 632    }
 633
 634    pub fn add_global_action<S, T, F>(&mut self, name: S, mut handler: F)
 635    where
 636        S: Into<String>,
 637        T: 'static + Any,
 638        F: 'static + FnMut(&T, &mut MutableAppContext),
 639    {
 640        let name = name.into();
 641        let name_clone = name.clone();
 642        let handler = Box::new(move |arg: &dyn Any, app: &mut MutableAppContext| {
 643            if let Some(arg) = arg.downcast_ref() {
 644                handler(arg, app);
 645            } else {
 646                log::error!("Could not downcast argument for action {}", name_clone);
 647            }
 648        });
 649
 650        self.global_actions.entry(name).or_default().push(handler);
 651    }
 652
 653    pub fn window_ids(&self) -> impl Iterator<Item = usize> + '_ {
 654        self.ctx.windows.keys().cloned()
 655    }
 656
 657    pub fn root_view<T: View>(&self, window_id: usize) -> Option<ViewHandle<T>> {
 658        self.ctx
 659            .windows
 660            .get(&window_id)
 661            .and_then(|window| window.root_view.clone().downcast::<T>())
 662    }
 663
 664    pub fn root_view_id(&self, window_id: usize) -> Option<usize> {
 665        self.ctx.root_view_id(window_id)
 666    }
 667
 668    pub fn focused_view_id(&self, window_id: usize) -> Option<usize> {
 669        self.ctx.focused_view_id(window_id)
 670    }
 671
 672    pub fn render_view(&self, window_id: usize, view_id: usize) -> Result<ElementBox> {
 673        self.ctx.render_view(window_id, view_id)
 674    }
 675
 676    pub fn render_views(&self, window_id: usize) -> HashMap<usize, ElementBox> {
 677        self.ctx.render_views(window_id)
 678    }
 679
 680    pub fn update<T, F: FnOnce() -> T>(&mut self, callback: F) -> T {
 681        self.pending_flushes += 1;
 682        let result = callback();
 683        self.flush_effects();
 684        result
 685    }
 686
 687    pub fn set_menus(&self, menus: Vec<Menu>) {
 688        self.platform.set_menus(menus);
 689    }
 690
 691    pub fn prompt_for_paths<F>(&self, options: PathPromptOptions, done_fn: F)
 692    where
 693        F: 'static + FnOnce(Option<Vec<PathBuf>>, &mut MutableAppContext),
 694    {
 695        let app = self.weak_self.as_ref().unwrap().upgrade().unwrap();
 696        let foreground = self.foreground.clone();
 697        self.platform().prompt_for_paths(
 698            options,
 699            Box::new(move |paths| {
 700                foreground
 701                    .spawn(async move { (done_fn)(paths, &mut *app.borrow_mut()) })
 702                    .detach();
 703            }),
 704        );
 705    }
 706
 707    pub fn prompt_for_new_path<F>(&self, directory: &Path, done_fn: F)
 708    where
 709        F: 'static + FnOnce(Option<PathBuf>, &mut MutableAppContext),
 710    {
 711        let app = self.weak_self.as_ref().unwrap().upgrade().unwrap();
 712        let foreground = self.foreground.clone();
 713        self.platform().prompt_for_new_path(
 714            directory,
 715            Box::new(move |path| {
 716                foreground
 717                    .spawn(async move { (done_fn)(path, &mut *app.borrow_mut()) })
 718                    .detach();
 719            }),
 720        );
 721    }
 722
 723    pub(crate) fn notify_view(&mut self, window_id: usize, view_id: usize) {
 724        self.pending_effects
 725            .push_back(Effect::ViewNotification { window_id, view_id });
 726    }
 727
 728    pub fn dispatch_action<T: 'static + Any>(
 729        &mut self,
 730        window_id: usize,
 731        responder_chain: Vec<usize>,
 732        name: &str,
 733        arg: T,
 734    ) {
 735        self.dispatch_action_any(window_id, &responder_chain, name, Box::new(arg).as_ref());
 736    }
 737
 738    pub(crate) fn dispatch_action_any(
 739        &mut self,
 740        window_id: usize,
 741        path: &[usize],
 742        name: &str,
 743        arg: &dyn Any,
 744    ) -> bool {
 745        self.pending_flushes += 1;
 746        let mut halted_dispatch = false;
 747
 748        for view_id in path.iter().rev() {
 749            if let Some(mut view) = self.ctx.views.remove(&(window_id, *view_id)) {
 750                let type_id = view.as_any().type_id();
 751
 752                if let Some((name, mut handlers)) = self
 753                    .actions
 754                    .get_mut(&type_id)
 755                    .and_then(|h| h.remove_entry(name))
 756                {
 757                    for handler in handlers.iter_mut().rev() {
 758                        let halt_dispatch = handler(view.as_mut(), arg, self, window_id, *view_id);
 759                        if halt_dispatch {
 760                            halted_dispatch = true;
 761                            break;
 762                        }
 763                    }
 764                    self.actions
 765                        .get_mut(&type_id)
 766                        .unwrap()
 767                        .insert(name, handlers);
 768                }
 769
 770                self.ctx.views.insert((window_id, *view_id), view);
 771
 772                if halted_dispatch {
 773                    break;
 774                }
 775            }
 776        }
 777
 778        if !halted_dispatch {
 779            self.dispatch_global_action_any(name, arg);
 780        }
 781
 782        self.flush_effects();
 783        halted_dispatch
 784    }
 785
 786    pub fn dispatch_global_action<T: 'static + Any>(&mut self, name: &str, arg: T) {
 787        self.dispatch_global_action_any(name, Box::new(arg).as_ref());
 788    }
 789
 790    fn dispatch_global_action_any(&mut self, name: &str, arg: &dyn Any) {
 791        if let Some((name, mut handlers)) = self.global_actions.remove_entry(name) {
 792            self.pending_flushes += 1;
 793            for handler in handlers.iter_mut().rev() {
 794                handler(arg, self);
 795            }
 796            self.global_actions.insert(name, handlers);
 797            self.flush_effects();
 798        }
 799    }
 800
 801    pub fn add_bindings<T: IntoIterator<Item = keymap::Binding>>(&mut self, bindings: T) {
 802        self.keystroke_matcher.add_bindings(bindings);
 803    }
 804
 805    pub fn dispatch_keystroke(
 806        &mut self,
 807        window_id: usize,
 808        responder_chain: Vec<usize>,
 809        keystroke: &Keystroke,
 810    ) -> Result<bool> {
 811        let mut context_chain = Vec::new();
 812        let mut context = keymap::Context::default();
 813        for view_id in &responder_chain {
 814            if let Some(view) = self.ctx.views.get(&(window_id, *view_id)) {
 815                context.extend(view.keymap_context(self.as_ref()));
 816                context_chain.push(context.clone());
 817            } else {
 818                return Err(anyhow!(
 819                    "View {} in responder chain does not exist",
 820                    view_id
 821                ));
 822            }
 823        }
 824
 825        let mut pending = false;
 826        for (i, ctx) in context_chain.iter().enumerate().rev() {
 827            match self
 828                .keystroke_matcher
 829                .push_keystroke(keystroke.clone(), responder_chain[i], ctx)
 830            {
 831                MatchResult::None => {}
 832                MatchResult::Pending => pending = true,
 833                MatchResult::Action { name, arg } => {
 834                    if self.dispatch_action_any(
 835                        window_id,
 836                        &responder_chain[0..=i],
 837                        &name,
 838                        arg.as_ref().map(|arg| arg.as_ref()).unwrap_or(&()),
 839                    ) {
 840                        return Ok(true);
 841                    }
 842                }
 843            }
 844        }
 845
 846        Ok(pending)
 847    }
 848
 849    pub fn add_model<T, F>(&mut self, build_model: F) -> ModelHandle<T>
 850    where
 851        T: Entity,
 852        F: FnOnce(&mut ModelContext<T>) -> T,
 853    {
 854        self.pending_flushes += 1;
 855        let model_id = post_inc(&mut self.next_entity_id);
 856        let handle = ModelHandle::new(model_id, &self.ctx.ref_counts);
 857        let mut ctx = ModelContext::new(self, model_id);
 858        let model = build_model(&mut ctx);
 859        self.ctx.models.insert(model_id, Box::new(model));
 860        self.flush_effects();
 861        handle
 862    }
 863
 864    pub fn add_window<T, F>(&mut self, build_root_view: F) -> (usize, ViewHandle<T>)
 865    where
 866        T: View,
 867        F: FnOnce(&mut ViewContext<T>) -> T,
 868    {
 869        self.pending_flushes += 1;
 870        let window_id = post_inc(&mut self.next_window_id);
 871        let root_view = self.add_view(window_id, build_root_view);
 872
 873        self.ctx.windows.insert(
 874            window_id,
 875            Window {
 876                root_view: root_view.clone().into(),
 877                focused_view_id: root_view.id(),
 878                invalidation: None,
 879            },
 880        );
 881        self.open_platform_window(window_id);
 882        root_view.update(self, |view, ctx| view.on_focus(ctx));
 883        self.flush_effects();
 884
 885        (window_id, root_view)
 886    }
 887
 888    pub fn remove_window(&mut self, window_id: usize) {
 889        self.ctx.windows.remove(&window_id);
 890        self.presenters_and_platform_windows.remove(&window_id);
 891        self.remove_dropped_entities();
 892    }
 893
 894    fn open_platform_window(&mut self, window_id: usize) {
 895        let mut window = self.platform.open_window(
 896            window_id,
 897            WindowOptions {
 898                bounds: RectF::new(vec2f(0., 0.), vec2f(1024., 768.)),
 899                title: "Zed".into(),
 900            },
 901            self.foreground.clone(),
 902        );
 903        let text_layout_cache = TextLayoutCache::new(self.platform.fonts());
 904        let presenter = Rc::new(RefCell::new(Presenter::new(
 905            window_id,
 906            self.ctx.font_cache.clone(),
 907            text_layout_cache,
 908            self.assets.clone(),
 909            self,
 910        )));
 911
 912        {
 913            let mut app = self.upgrade();
 914            let presenter = presenter.clone();
 915            window.on_event(Box::new(move |event| {
 916                app.update(|ctx| {
 917                    if let Event::KeyDown { keystroke, .. } = &event {
 918                        if ctx
 919                            .dispatch_keystroke(
 920                                window_id,
 921                                presenter.borrow().dispatch_path(ctx.as_ref()),
 922                                keystroke,
 923                            )
 924                            .unwrap()
 925                        {
 926                            return;
 927                        }
 928                    }
 929
 930                    presenter.borrow_mut().dispatch_event(event, ctx);
 931                })
 932            }));
 933        }
 934
 935        {
 936            let mut app = self.upgrade();
 937            let presenter = presenter.clone();
 938            window.on_resize(Box::new(move |window| {
 939                app.update(|ctx| {
 940                    let scene = presenter.borrow_mut().build_scene(
 941                        window.size(),
 942                        window.scale_factor(),
 943                        ctx,
 944                    );
 945                    window.present_scene(scene);
 946                })
 947            }));
 948        }
 949
 950        {
 951            let mut app = self.upgrade();
 952            window.on_close(Box::new(move || {
 953                app.update(|ctx| ctx.remove_window(window_id));
 954            }));
 955        }
 956
 957        self.presenters_and_platform_windows
 958            .insert(window_id, (presenter.clone(), window));
 959
 960        self.on_debug_elements(window_id, move |ctx| {
 961            presenter.borrow().debug_elements(ctx).unwrap()
 962        });
 963    }
 964
 965    pub fn add_view<T, F>(&mut self, window_id: usize, build_view: F) -> ViewHandle<T>
 966    where
 967        T: View,
 968        F: FnOnce(&mut ViewContext<T>) -> T,
 969    {
 970        self.add_option_view(window_id, |ctx| Some(build_view(ctx)))
 971            .unwrap()
 972    }
 973
 974    pub fn add_option_view<T, F>(
 975        &mut self,
 976        window_id: usize,
 977        build_view: F,
 978    ) -> Option<ViewHandle<T>>
 979    where
 980        T: View,
 981        F: FnOnce(&mut ViewContext<T>) -> Option<T>,
 982    {
 983        let view_id = post_inc(&mut self.next_entity_id);
 984        self.pending_flushes += 1;
 985        let handle = ViewHandle::new(window_id, view_id, &self.ctx.ref_counts);
 986        let mut ctx = ViewContext::new(self, window_id, view_id);
 987        let handle = if let Some(view) = build_view(&mut ctx) {
 988            self.ctx.views.insert((window_id, view_id), Box::new(view));
 989            if let Some(window) = self.ctx.windows.get_mut(&window_id) {
 990                window
 991                    .invalidation
 992                    .get_or_insert_with(Default::default)
 993                    .updated
 994                    .insert(view_id);
 995            }
 996            Some(handle)
 997        } else {
 998            None
 999        };
1000        self.flush_effects();
1001        handle
1002    }
1003
1004    fn remove_dropped_entities(&mut self) {
1005        loop {
1006            let (dropped_models, dropped_views, dropped_values) =
1007                self.ctx.ref_counts.lock().take_dropped();
1008            if dropped_models.is_empty() && dropped_views.is_empty() && dropped_values.is_empty() {
1009                break;
1010            }
1011
1012            for model_id in dropped_models {
1013                self.ctx.models.remove(&model_id);
1014                self.subscriptions.remove(&model_id);
1015                self.model_observations.remove(&model_id);
1016            }
1017
1018            for (window_id, view_id) in dropped_views {
1019                self.subscriptions.remove(&view_id);
1020                self.model_observations.remove(&view_id);
1021                self.ctx.views.remove(&(window_id, view_id));
1022                let change_focus_to = self.ctx.windows.get_mut(&window_id).and_then(|window| {
1023                    window
1024                        .invalidation
1025                        .get_or_insert_with(Default::default)
1026                        .removed
1027                        .push(view_id);
1028                    if window.focused_view_id == view_id {
1029                        Some(window.root_view.id())
1030                    } else {
1031                        None
1032                    }
1033                });
1034
1035                if let Some(view_id) = change_focus_to {
1036                    self.focus(window_id, view_id);
1037                }
1038            }
1039
1040            let mut values = self.ctx.values.write();
1041            for key in dropped_values {
1042                values.remove(&key);
1043            }
1044        }
1045    }
1046
1047    fn flush_effects(&mut self) {
1048        self.pending_flushes = self.pending_flushes.saturating_sub(1);
1049
1050        if !self.flushing_effects && self.pending_flushes == 0 {
1051            self.flushing_effects = true;
1052
1053            loop {
1054                if let Some(effect) = self.pending_effects.pop_front() {
1055                    match effect {
1056                        Effect::Event { entity_id, payload } => self.emit_event(entity_id, payload),
1057                        Effect::ModelNotification { model_id } => {
1058                            self.notify_model_observers(model_id)
1059                        }
1060                        Effect::ViewNotification { window_id, view_id } => {
1061                            self.notify_view_observers(window_id, view_id)
1062                        }
1063                        Effect::Focus { window_id, view_id } => {
1064                            self.focus(window_id, view_id);
1065                        }
1066                    }
1067                    self.remove_dropped_entities();
1068                } else {
1069                    self.remove_dropped_entities();
1070                    self.update_windows();
1071
1072                    if self.pending_effects.is_empty() {
1073                        self.flushing_effects = false;
1074                        break;
1075                    }
1076                }
1077            }
1078        }
1079    }
1080
1081    fn update_windows(&mut self) {
1082        let mut invalidations = HashMap::new();
1083        for (window_id, window) in &mut self.ctx.windows {
1084            if let Some(invalidation) = window.invalidation.take() {
1085                invalidations.insert(*window_id, invalidation);
1086            }
1087        }
1088
1089        for (window_id, invalidation) in invalidations {
1090            if let Some((presenter, mut window)) =
1091                self.presenters_and_platform_windows.remove(&window_id)
1092            {
1093                {
1094                    let mut presenter = presenter.borrow_mut();
1095                    presenter.invalidate(invalidation, self.as_ref());
1096                    let scene = presenter.build_scene(window.size(), window.scale_factor(), self);
1097                    window.present_scene(scene);
1098                }
1099                self.presenters_and_platform_windows
1100                    .insert(window_id, (presenter, window));
1101            }
1102        }
1103    }
1104
1105    fn emit_event(&mut self, entity_id: usize, payload: Box<dyn Any>) {
1106        if let Some(subscriptions) = self.subscriptions.remove(&entity_id) {
1107            for mut subscription in subscriptions {
1108                let alive = match &mut subscription {
1109                    Subscription::FromModel { model_id, callback } => {
1110                        if let Some(mut model) = self.ctx.models.remove(model_id) {
1111                            callback(model.as_any_mut(), payload.as_ref(), self, *model_id);
1112                            self.ctx.models.insert(*model_id, model);
1113                            true
1114                        } else {
1115                            false
1116                        }
1117                    }
1118                    Subscription::FromView {
1119                        window_id,
1120                        view_id,
1121                        callback,
1122                    } => {
1123                        if let Some(mut view) = self.ctx.views.remove(&(*window_id, *view_id)) {
1124                            callback(
1125                                view.as_any_mut(),
1126                                payload.as_ref(),
1127                                self,
1128                                *window_id,
1129                                *view_id,
1130                            );
1131                            self.ctx.views.insert((*window_id, *view_id), view);
1132                            true
1133                        } else {
1134                            false
1135                        }
1136                    }
1137                };
1138
1139                if alive {
1140                    self.subscriptions
1141                        .entry(entity_id)
1142                        .or_default()
1143                        .push(subscription);
1144                }
1145            }
1146        }
1147    }
1148
1149    fn notify_model_observers(&mut self, observed_id: usize) {
1150        if let Some(observations) = self.model_observations.remove(&observed_id) {
1151            if self.ctx.models.contains_key(&observed_id) {
1152                for mut observation in observations {
1153                    let alive = match &mut observation {
1154                        ModelObservation::FromModel { model_id, callback } => {
1155                            if let Some(mut model) = self.ctx.models.remove(model_id) {
1156                                callback(model.as_any_mut(), observed_id, self, *model_id);
1157                                self.ctx.models.insert(*model_id, model);
1158                                true
1159                            } else {
1160                                false
1161                            }
1162                        }
1163                        ModelObservation::FromView {
1164                            window_id,
1165                            view_id,
1166                            callback,
1167                        } => {
1168                            if let Some(mut view) = self.ctx.views.remove(&(*window_id, *view_id)) {
1169                                callback(
1170                                    view.as_any_mut(),
1171                                    observed_id,
1172                                    self,
1173                                    *window_id,
1174                                    *view_id,
1175                                );
1176                                self.ctx.views.insert((*window_id, *view_id), view);
1177                                true
1178                            } else {
1179                                false
1180                            }
1181                        }
1182                    };
1183
1184                    if alive {
1185                        self.model_observations
1186                            .entry(observed_id)
1187                            .or_default()
1188                            .push(observation);
1189                    }
1190                }
1191            }
1192        }
1193    }
1194
1195    fn notify_view_observers(&mut self, window_id: usize, view_id: usize) {
1196        if let Some(window) = self.ctx.windows.get_mut(&window_id) {
1197            window
1198                .invalidation
1199                .get_or_insert_with(Default::default)
1200                .updated
1201                .insert(view_id);
1202        }
1203
1204        if let Some(observations) = self.view_observations.remove(&view_id) {
1205            if self.ctx.views.contains_key(&(window_id, view_id)) {
1206                for mut observation in observations {
1207                    let alive = if let Some(mut view) = self
1208                        .ctx
1209                        .views
1210                        .remove(&(observation.window_id, observation.view_id))
1211                    {
1212                        (observation.callback)(
1213                            view.as_any_mut(),
1214                            view_id,
1215                            window_id,
1216                            self,
1217                            observation.window_id,
1218                            observation.view_id,
1219                        );
1220                        self.ctx
1221                            .views
1222                            .insert((observation.window_id, observation.view_id), view);
1223                        true
1224                    } else {
1225                        false
1226                    };
1227
1228                    if alive {
1229                        self.view_observations
1230                            .entry(view_id)
1231                            .or_default()
1232                            .push(observation);
1233                    }
1234                }
1235            }
1236        }
1237    }
1238
1239    fn focus(&mut self, window_id: usize, focused_id: usize) {
1240        if self
1241            .ctx
1242            .windows
1243            .get(&window_id)
1244            .map(|w| w.focused_view_id)
1245            .map_or(false, |cur_focused| cur_focused == focused_id)
1246        {
1247            return;
1248        }
1249
1250        self.pending_flushes += 1;
1251
1252        let blurred_id = self.ctx.windows.get_mut(&window_id).map(|window| {
1253            let blurred_id = window.focused_view_id;
1254            window.focused_view_id = focused_id;
1255            blurred_id
1256        });
1257
1258        if let Some(blurred_id) = blurred_id {
1259            if let Some(mut blurred_view) = self.ctx.views.remove(&(window_id, blurred_id)) {
1260                blurred_view.on_blur(self, window_id, blurred_id);
1261                self.ctx.views.insert((window_id, blurred_id), blurred_view);
1262            }
1263        }
1264
1265        if let Some(mut focused_view) = self.ctx.views.remove(&(window_id, focused_id)) {
1266            focused_view.on_focus(self, window_id, focused_id);
1267            self.ctx.views.insert((window_id, focused_id), focused_view);
1268        }
1269
1270        self.flush_effects();
1271    }
1272
1273    pub fn spawn<F, Fut, T>(&self, f: F) -> Task<T>
1274    where
1275        F: FnOnce(AsyncAppContext) -> Fut,
1276        Fut: 'static + Future<Output = T>,
1277        T: 'static,
1278    {
1279        let ctx = AsyncAppContext(self.weak_self.as_ref().unwrap().upgrade().unwrap());
1280        self.foreground.spawn(f(ctx))
1281    }
1282
1283    pub fn write_to_clipboard(&self, item: ClipboardItem) {
1284        self.platform.write_to_clipboard(item);
1285    }
1286
1287    pub fn read_from_clipboard(&self) -> Option<ClipboardItem> {
1288        self.platform.read_from_clipboard()
1289    }
1290}
1291
1292impl ReadModel for MutableAppContext {
1293    fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T {
1294        if let Some(model) = self.ctx.models.get(&handle.model_id) {
1295            model
1296                .as_any()
1297                .downcast_ref()
1298                .expect("downcast is type safe")
1299        } else {
1300            panic!("circular model reference");
1301        }
1302    }
1303}
1304
1305impl UpdateModel for MutableAppContext {
1306    fn update_model<T, F, S>(&mut self, handle: &ModelHandle<T>, update: F) -> S
1307    where
1308        T: Entity,
1309        F: FnOnce(&mut T, &mut ModelContext<T>) -> S,
1310    {
1311        if let Some(mut model) = self.ctx.models.remove(&handle.model_id) {
1312            self.pending_flushes += 1;
1313            let mut ctx = ModelContext::new(self, handle.model_id);
1314            let result = update(
1315                model
1316                    .as_any_mut()
1317                    .downcast_mut()
1318                    .expect("downcast is type safe"),
1319                &mut ctx,
1320            );
1321            self.ctx.models.insert(handle.model_id, model);
1322            self.flush_effects();
1323            result
1324        } else {
1325            panic!("circular model update");
1326        }
1327    }
1328}
1329
1330impl ReadView for MutableAppContext {
1331    fn read_view<T: View>(&self, handle: &ViewHandle<T>) -> &T {
1332        if let Some(view) = self.ctx.views.get(&(handle.window_id, handle.view_id)) {
1333            view.as_any().downcast_ref().expect("downcast is type safe")
1334        } else {
1335            panic!("circular view reference");
1336        }
1337    }
1338}
1339
1340impl UpdateView for MutableAppContext {
1341    fn update_view<T, F, S>(&mut self, handle: &ViewHandle<T>, update: F) -> S
1342    where
1343        T: View,
1344        F: FnOnce(&mut T, &mut ViewContext<T>) -> S,
1345    {
1346        self.pending_flushes += 1;
1347        let mut view = self
1348            .ctx
1349            .views
1350            .remove(&(handle.window_id, handle.view_id))
1351            .expect("circular view update");
1352
1353        let mut ctx = ViewContext::new(self, handle.window_id, handle.view_id);
1354        let result = update(
1355            view.as_any_mut()
1356                .downcast_mut()
1357                .expect("downcast is type safe"),
1358            &mut ctx,
1359        );
1360        self.ctx
1361            .views
1362            .insert((handle.window_id, handle.view_id), view);
1363        self.flush_effects();
1364        result
1365    }
1366}
1367
1368impl AsRef<AppContext> for MutableAppContext {
1369    fn as_ref(&self) -> &AppContext {
1370        &self.ctx
1371    }
1372}
1373
1374pub struct AppContext {
1375    models: HashMap<usize, Box<dyn AnyModel>>,
1376    views: HashMap<(usize, usize), Box<dyn AnyView>>,
1377    windows: HashMap<usize, Window>,
1378    values: RwLock<HashMap<(TypeId, usize), Box<dyn Any>>>,
1379    background: Arc<executor::Background>,
1380    ref_counts: Arc<Mutex<RefCounts>>,
1381    thread_pool: scoped_pool::Pool,
1382    font_cache: Arc<FontCache>,
1383}
1384
1385impl AppContext {
1386    pub fn root_view_id(&self, window_id: usize) -> Option<usize> {
1387        self.windows
1388            .get(&window_id)
1389            .map(|window| window.root_view.id())
1390    }
1391
1392    pub fn focused_view_id(&self, window_id: usize) -> Option<usize> {
1393        self.windows
1394            .get(&window_id)
1395            .map(|window| window.focused_view_id)
1396    }
1397
1398    pub fn render_view(&self, window_id: usize, view_id: usize) -> Result<ElementBox> {
1399        self.views
1400            .get(&(window_id, view_id))
1401            .map(|v| v.render(self))
1402            .ok_or(anyhow!("view not found"))
1403    }
1404
1405    pub fn render_views(&self, window_id: usize) -> HashMap<usize, ElementBox> {
1406        self.views
1407            .iter()
1408            .filter_map(|((win_id, view_id), view)| {
1409                if *win_id == window_id {
1410                    Some((*view_id, view.render(self)))
1411                } else {
1412                    None
1413                }
1414            })
1415            .collect::<HashMap<_, ElementBox>>()
1416    }
1417
1418    pub fn background_executor(&self) -> &Arc<executor::Background> {
1419        &self.background
1420    }
1421
1422    pub fn font_cache(&self) -> &FontCache {
1423        &self.font_cache
1424    }
1425
1426    pub fn thread_pool(&self) -> &scoped_pool::Pool {
1427        &self.thread_pool
1428    }
1429
1430    pub fn value<Tag: 'static, T: 'static + Default>(&self, id: usize) -> ValueHandle<T> {
1431        let key = (TypeId::of::<Tag>(), id);
1432        let mut values = self.values.write();
1433        values.entry(key).or_insert_with(|| Box::new(T::default()));
1434        ValueHandle::new(TypeId::of::<Tag>(), id, &self.ref_counts)
1435    }
1436}
1437
1438impl ReadModel for AppContext {
1439    fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T {
1440        if let Some(model) = self.models.get(&handle.model_id) {
1441            model
1442                .as_any()
1443                .downcast_ref()
1444                .expect("downcast should be type safe")
1445        } else {
1446            panic!("circular model reference");
1447        }
1448    }
1449}
1450
1451impl ReadView for AppContext {
1452    fn read_view<T: View>(&self, handle: &ViewHandle<T>) -> &T {
1453        if let Some(view) = self.views.get(&(handle.window_id, handle.view_id)) {
1454            view.as_any()
1455                .downcast_ref()
1456                .expect("downcast should be type safe")
1457        } else {
1458            panic!("circular view reference");
1459        }
1460    }
1461}
1462
1463struct Window {
1464    root_view: AnyViewHandle,
1465    focused_view_id: usize,
1466    invalidation: Option<WindowInvalidation>,
1467}
1468
1469#[derive(Default, Clone)]
1470pub struct WindowInvalidation {
1471    pub updated: HashSet<usize>,
1472    pub removed: Vec<usize>,
1473}
1474
1475pub enum Effect {
1476    Event {
1477        entity_id: usize,
1478        payload: Box<dyn Any>,
1479    },
1480    ModelNotification {
1481        model_id: usize,
1482    },
1483    ViewNotification {
1484        window_id: usize,
1485        view_id: usize,
1486    },
1487    Focus {
1488        window_id: usize,
1489        view_id: usize,
1490    },
1491}
1492
1493pub trait AnyModel: Send + Sync {
1494    fn as_any(&self) -> &dyn Any;
1495    fn as_any_mut(&mut self) -> &mut dyn Any;
1496}
1497
1498impl<T> AnyModel for T
1499where
1500    T: Entity,
1501{
1502    fn as_any(&self) -> &dyn Any {
1503        self
1504    }
1505
1506    fn as_any_mut(&mut self) -> &mut dyn Any {
1507        self
1508    }
1509}
1510
1511pub trait AnyView: Send + Sync {
1512    fn as_any(&self) -> &dyn Any;
1513    fn as_any_mut(&mut self) -> &mut dyn Any;
1514    fn ui_name(&self) -> &'static str;
1515    fn render<'a>(&self, app: &AppContext) -> ElementBox;
1516    fn on_focus(&mut self, app: &mut MutableAppContext, window_id: usize, view_id: usize);
1517    fn on_blur(&mut self, app: &mut MutableAppContext, window_id: usize, view_id: usize);
1518    fn keymap_context(&self, app: &AppContext) -> keymap::Context;
1519}
1520
1521impl<T> AnyView for T
1522where
1523    T: View,
1524{
1525    fn as_any(&self) -> &dyn Any {
1526        self
1527    }
1528
1529    fn as_any_mut(&mut self) -> &mut dyn Any {
1530        self
1531    }
1532
1533    fn ui_name(&self) -> &'static str {
1534        T::ui_name()
1535    }
1536
1537    fn render<'a>(&self, app: &AppContext) -> ElementBox {
1538        View::render(self, app)
1539    }
1540
1541    fn on_focus(&mut self, app: &mut MutableAppContext, window_id: usize, view_id: usize) {
1542        let mut ctx = ViewContext::new(app, window_id, view_id);
1543        View::on_focus(self, &mut ctx);
1544    }
1545
1546    fn on_blur(&mut self, app: &mut MutableAppContext, window_id: usize, view_id: usize) {
1547        let mut ctx = ViewContext::new(app, window_id, view_id);
1548        View::on_blur(self, &mut ctx);
1549    }
1550
1551    fn keymap_context(&self, app: &AppContext) -> keymap::Context {
1552        View::keymap_context(self, app)
1553    }
1554}
1555
1556pub struct ModelContext<'a, T: ?Sized> {
1557    app: &'a mut MutableAppContext,
1558    model_id: usize,
1559    model_type: PhantomData<T>,
1560    halt_stream: bool,
1561}
1562
1563impl<'a, T: Entity> ModelContext<'a, T> {
1564    fn new(app: &'a mut MutableAppContext, model_id: usize) -> Self {
1565        Self {
1566            app,
1567            model_id,
1568            model_type: PhantomData,
1569            halt_stream: false,
1570        }
1571    }
1572
1573    pub fn background_executor(&self) -> &Arc<executor::Background> {
1574        &self.app.ctx.background
1575    }
1576
1577    pub fn thread_pool(&self) -> &scoped_pool::Pool {
1578        &self.app.ctx.thread_pool
1579    }
1580
1581    pub fn halt_stream(&mut self) {
1582        self.halt_stream = true;
1583    }
1584
1585    pub fn model_id(&self) -> usize {
1586        self.model_id
1587    }
1588
1589    pub fn add_model<S, F>(&mut self, build_model: F) -> ModelHandle<S>
1590    where
1591        S: Entity,
1592        F: FnOnce(&mut ModelContext<S>) -> S,
1593    {
1594        self.app.add_model(build_model)
1595    }
1596
1597    pub fn subscribe<S: Entity, F>(&mut self, handle: &ModelHandle<S>, mut callback: F)
1598    where
1599        S::Event: 'static,
1600        F: 'static + FnMut(&mut T, &S::Event, &mut ModelContext<T>),
1601    {
1602        self.app
1603            .subscriptions
1604            .entry(handle.model_id)
1605            .or_default()
1606            .push(Subscription::FromModel {
1607                model_id: self.model_id,
1608                callback: Box::new(move |model, payload, app, model_id| {
1609                    let model = model.downcast_mut().expect("downcast is type safe");
1610                    let payload = payload.downcast_ref().expect("downcast is type safe");
1611                    let mut ctx = ModelContext::new(app, model_id);
1612                    callback(model, payload, &mut ctx);
1613                }),
1614            });
1615    }
1616
1617    pub fn emit(&mut self, payload: T::Event) {
1618        self.app.pending_effects.push_back(Effect::Event {
1619            entity_id: self.model_id,
1620            payload: Box::new(payload),
1621        });
1622    }
1623
1624    pub fn observe<S, F>(&mut self, handle: &ModelHandle<S>, mut callback: F)
1625    where
1626        S: Entity,
1627        F: 'static + FnMut(&mut T, ModelHandle<S>, &mut ModelContext<T>),
1628    {
1629        self.app
1630            .model_observations
1631            .entry(handle.model_id)
1632            .or_default()
1633            .push(ModelObservation::FromModel {
1634                model_id: self.model_id,
1635                callback: Box::new(move |model, observed_id, app, model_id| {
1636                    let model = model.downcast_mut().expect("downcast is type safe");
1637                    let observed = ModelHandle::new(observed_id, &app.ctx.ref_counts);
1638                    let mut ctx = ModelContext::new(app, model_id);
1639                    callback(model, observed, &mut ctx);
1640                }),
1641            });
1642    }
1643
1644    pub fn notify(&mut self) {
1645        self.app
1646            .pending_effects
1647            .push_back(Effect::ModelNotification {
1648                model_id: self.model_id,
1649            });
1650    }
1651
1652    pub fn handle(&self) -> ModelHandle<T> {
1653        ModelHandle::new(self.model_id, &self.app.ctx.ref_counts)
1654    }
1655
1656    pub fn spawn<F, Fut, S>(&self, f: F) -> Task<S>
1657    where
1658        F: FnOnce(ModelHandle<T>, AsyncAppContext) -> Fut,
1659        Fut: 'static + Future<Output = S>,
1660        S: 'static,
1661    {
1662        let handle = self.handle();
1663        self.app.spawn(|ctx| f(handle, ctx))
1664    }
1665}
1666
1667impl<M> AsRef<AppContext> for ModelContext<'_, M> {
1668    fn as_ref(&self) -> &AppContext {
1669        &self.app.ctx
1670    }
1671}
1672
1673impl<M> AsMut<MutableAppContext> for ModelContext<'_, M> {
1674    fn as_mut(&mut self) -> &mut MutableAppContext {
1675        self.app
1676    }
1677}
1678
1679impl<M> ReadModel for ModelContext<'_, M> {
1680    fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T {
1681        self.app.read_model(handle)
1682    }
1683}
1684
1685impl<M> UpdateModel for ModelContext<'_, M> {
1686    fn update_model<T, F, S>(&mut self, handle: &ModelHandle<T>, update: F) -> S
1687    where
1688        T: Entity,
1689        F: FnOnce(&mut T, &mut ModelContext<T>) -> S,
1690    {
1691        self.app.update_model(handle, update)
1692    }
1693}
1694
1695pub struct ViewContext<'a, T: ?Sized> {
1696    app: &'a mut MutableAppContext,
1697    window_id: usize,
1698    view_id: usize,
1699    view_type: PhantomData<T>,
1700    halt_action_dispatch: bool,
1701}
1702
1703impl<'a, T: View> ViewContext<'a, T> {
1704    fn new(app: &'a mut MutableAppContext, window_id: usize, view_id: usize) -> Self {
1705        Self {
1706            app,
1707            window_id,
1708            view_id,
1709            view_type: PhantomData,
1710            halt_action_dispatch: true,
1711        }
1712    }
1713
1714    pub fn handle(&self) -> ViewHandle<T> {
1715        ViewHandle::new(self.window_id, self.view_id, &self.app.ctx.ref_counts)
1716    }
1717
1718    pub fn window_id(&self) -> usize {
1719        self.window_id
1720    }
1721
1722    pub fn view_id(&self) -> usize {
1723        self.view_id
1724    }
1725
1726    pub fn foreground(&self) -> &Rc<executor::Foreground> {
1727        self.app.foreground_executor()
1728    }
1729
1730    pub fn background_executor(&self) -> &Arc<executor::Background> {
1731        &self.app.ctx.background
1732    }
1733
1734    pub fn prompt_for_paths<F>(&self, options: PathPromptOptions, done_fn: F)
1735    where
1736        F: 'static + FnOnce(Option<Vec<PathBuf>>, &mut MutableAppContext),
1737    {
1738        self.app.prompt_for_paths(options, done_fn)
1739    }
1740
1741    pub fn prompt_for_new_path<F>(&self, directory: &Path, done_fn: F)
1742    where
1743        F: 'static + FnOnce(Option<PathBuf>, &mut MutableAppContext),
1744    {
1745        self.app.prompt_for_new_path(directory, done_fn)
1746    }
1747
1748    pub fn debug_elements(&self) -> crate::json::Value {
1749        self.app.debug_elements(self.window_id).unwrap()
1750    }
1751
1752    pub fn focus<S>(&mut self, handle: S)
1753    where
1754        S: Into<AnyViewHandle>,
1755    {
1756        let handle = handle.into();
1757        self.app.pending_effects.push_back(Effect::Focus {
1758            window_id: handle.window_id,
1759            view_id: handle.view_id,
1760        });
1761    }
1762
1763    pub fn focus_self(&mut self) {
1764        self.app.pending_effects.push_back(Effect::Focus {
1765            window_id: self.window_id,
1766            view_id: self.view_id,
1767        });
1768    }
1769
1770    pub fn add_model<S, F>(&mut self, build_model: F) -> ModelHandle<S>
1771    where
1772        S: Entity,
1773        F: FnOnce(&mut ModelContext<S>) -> S,
1774    {
1775        self.app.add_model(build_model)
1776    }
1777
1778    pub fn add_view<S, F>(&mut self, build_view: F) -> ViewHandle<S>
1779    where
1780        S: View,
1781        F: FnOnce(&mut ViewContext<S>) -> S,
1782    {
1783        self.app.add_view(self.window_id, build_view)
1784    }
1785
1786    pub fn add_option_view<S, F>(&mut self, build_view: F) -> Option<ViewHandle<S>>
1787    where
1788        S: View,
1789        F: FnOnce(&mut ViewContext<S>) -> Option<S>,
1790    {
1791        self.app.add_option_view(self.window_id, build_view)
1792    }
1793
1794    pub fn subscribe_to_model<E, F>(&mut self, handle: &ModelHandle<E>, mut callback: F)
1795    where
1796        E: Entity,
1797        E::Event: 'static,
1798        F: 'static + FnMut(&mut T, ModelHandle<E>, &E::Event, &mut ViewContext<T>),
1799    {
1800        let emitter_handle = handle.downgrade();
1801        self.subscribe(handle, move |model, payload, ctx| {
1802            if let Some(emitter_handle) = emitter_handle.upgrade(ctx.as_ref()) {
1803                callback(model, emitter_handle, payload, ctx);
1804            }
1805        });
1806    }
1807
1808    pub fn subscribe_to_view<V, F>(&mut self, handle: &ViewHandle<V>, mut callback: F)
1809    where
1810        V: View,
1811        V::Event: 'static,
1812        F: 'static + FnMut(&mut T, ViewHandle<V>, &V::Event, &mut ViewContext<T>),
1813    {
1814        let emitter_handle = handle.downgrade();
1815        self.subscribe(handle, move |view, payload, ctx| {
1816            if let Some(emitter_handle) = emitter_handle.upgrade(ctx.as_ref()) {
1817                callback(view, emitter_handle, payload, ctx);
1818            }
1819        });
1820    }
1821
1822    pub fn subscribe<E, F>(&mut self, handle: &impl Handle<E>, mut callback: F)
1823    where
1824        E: Entity,
1825        E::Event: 'static,
1826        F: 'static + FnMut(&mut T, &E::Event, &mut ViewContext<T>),
1827    {
1828        self.app
1829            .subscriptions
1830            .entry(handle.id())
1831            .or_default()
1832            .push(Subscription::FromView {
1833                window_id: self.window_id,
1834                view_id: self.view_id,
1835                callback: Box::new(move |entity, payload, app, window_id, view_id| {
1836                    let entity = entity.downcast_mut().expect("downcast is type safe");
1837                    let payload = payload.downcast_ref().expect("downcast is type safe");
1838                    let mut ctx = ViewContext::new(app, window_id, view_id);
1839                    callback(entity, payload, &mut ctx);
1840                }),
1841            });
1842    }
1843
1844    pub fn emit(&mut self, payload: T::Event) {
1845        self.app.pending_effects.push_back(Effect::Event {
1846            entity_id: self.view_id,
1847            payload: Box::new(payload),
1848        });
1849    }
1850
1851    pub fn observe_model<S, F>(&mut self, handle: &ModelHandle<S>, mut callback: F)
1852    where
1853        S: Entity,
1854        F: 'static + FnMut(&mut T, ModelHandle<S>, &mut ViewContext<T>),
1855    {
1856        self.app
1857            .model_observations
1858            .entry(handle.id())
1859            .or_default()
1860            .push(ModelObservation::FromView {
1861                window_id: self.window_id,
1862                view_id: self.view_id,
1863                callback: Box::new(move |view, observed_id, app, window_id, view_id| {
1864                    let view = view.downcast_mut().expect("downcast is type safe");
1865                    let observed = ModelHandle::new(observed_id, &app.ctx.ref_counts);
1866                    let mut ctx = ViewContext::new(app, window_id, view_id);
1867                    callback(view, observed, &mut ctx);
1868                }),
1869            });
1870    }
1871
1872    pub fn observe_view<S, F>(&mut self, handle: &ViewHandle<S>, mut callback: F)
1873    where
1874        S: View,
1875        F: 'static + FnMut(&mut T, ViewHandle<S>, &mut ViewContext<T>),
1876    {
1877        self.app
1878            .view_observations
1879            .entry(handle.id())
1880            .or_default()
1881            .push(ViewObservation {
1882                window_id: self.window_id,
1883                view_id: self.view_id,
1884                callback: Box::new(
1885                    move |view,
1886                          observed_view_id,
1887                          observed_window_id,
1888                          app,
1889                          observing_window_id,
1890                          observing_view_id| {
1891                        let view = view.downcast_mut().expect("downcast is type safe");
1892                        let observed_handle = ViewHandle::new(
1893                            observed_view_id,
1894                            observed_window_id,
1895                            &app.ctx.ref_counts,
1896                        );
1897                        let mut ctx = ViewContext::new(app, observing_window_id, observing_view_id);
1898                        callback(view, observed_handle, &mut ctx);
1899                    },
1900                ),
1901            });
1902    }
1903
1904    pub fn notify(&mut self) {
1905        self.app.notify_view(self.window_id, self.view_id);
1906    }
1907
1908    pub fn propagate_action(&mut self) {
1909        self.halt_action_dispatch = false;
1910    }
1911
1912    pub fn spawn<F, Fut, S>(&self, f: F) -> Task<S>
1913    where
1914        F: FnOnce(ViewHandle<T>, AsyncAppContext) -> Fut,
1915        Fut: 'static + Future<Output = S>,
1916        S: 'static,
1917    {
1918        let handle = self.handle();
1919        self.app.spawn(|ctx| f(handle, ctx))
1920    }
1921}
1922
1923impl AsRef<AppContext> for &AppContext {
1924    fn as_ref(&self) -> &AppContext {
1925        self
1926    }
1927}
1928
1929impl<M> AsRef<AppContext> for ViewContext<'_, M> {
1930    fn as_ref(&self) -> &AppContext {
1931        &self.app.ctx
1932    }
1933}
1934
1935impl<M> AsMut<MutableAppContext> for ViewContext<'_, M> {
1936    fn as_mut(&mut self) -> &mut MutableAppContext {
1937        self.app
1938    }
1939}
1940
1941impl<V> ReadModel for ViewContext<'_, V> {
1942    fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T {
1943        self.app.read_model(handle)
1944    }
1945}
1946
1947impl<V: View> UpdateModel for ViewContext<'_, V> {
1948    fn update_model<T, F, S>(&mut self, handle: &ModelHandle<T>, update: F) -> S
1949    where
1950        T: Entity,
1951        F: FnOnce(&mut T, &mut ModelContext<T>) -> S,
1952    {
1953        self.app.update_model(handle, update)
1954    }
1955}
1956
1957impl<V: View> ReadView for ViewContext<'_, V> {
1958    fn read_view<T: View>(&self, handle: &ViewHandle<T>) -> &T {
1959        self.app.read_view(handle)
1960    }
1961}
1962
1963impl<V: View> UpdateView for ViewContext<'_, V> {
1964    fn update_view<T, F, S>(&mut self, handle: &ViewHandle<T>, update: F) -> S
1965    where
1966        T: View,
1967        F: FnOnce(&mut T, &mut ViewContext<T>) -> S,
1968    {
1969        self.app.update_view(handle, update)
1970    }
1971}
1972
1973pub trait Handle<T> {
1974    fn id(&self) -> usize;
1975    fn location(&self) -> EntityLocation;
1976}
1977
1978#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash)]
1979pub enum EntityLocation {
1980    Model(usize),
1981    View(usize, usize),
1982}
1983
1984pub struct ModelHandle<T> {
1985    model_id: usize,
1986    model_type: PhantomData<T>,
1987    ref_counts: Arc<Mutex<RefCounts>>,
1988}
1989
1990impl<T: Entity> ModelHandle<T> {
1991    fn new(model_id: usize, ref_counts: &Arc<Mutex<RefCounts>>) -> Self {
1992        ref_counts.lock().inc_model(model_id);
1993        Self {
1994            model_id,
1995            model_type: PhantomData,
1996            ref_counts: ref_counts.clone(),
1997        }
1998    }
1999
2000    pub fn downgrade(&self) -> WeakModelHandle<T> {
2001        WeakModelHandle::new(self.model_id)
2002    }
2003
2004    pub fn id(&self) -> usize {
2005        self.model_id
2006    }
2007
2008    pub fn read<'a, A: ReadModel>(&self, app: &'a A) -> &'a T {
2009        app.read_model(self)
2010    }
2011
2012    pub fn read_with<'a, A, F, S>(&self, ctx: &A, read: F) -> S
2013    where
2014        A: ReadModelWith,
2015        F: FnOnce(&T, &AppContext) -> S,
2016    {
2017        ctx.read_model_with(self, read)
2018    }
2019
2020    pub fn update<A, F, S>(&self, app: &mut A, update: F) -> S
2021    where
2022        A: UpdateModel,
2023        F: FnOnce(&mut T, &mut ModelContext<T>) -> S,
2024    {
2025        app.update_model(self, update)
2026    }
2027
2028    pub fn condition(
2029        &self,
2030        ctx: &TestAppContext,
2031        predicate: impl FnMut(&T, &AppContext) -> bool,
2032    ) -> impl Future<Output = ()> {
2033        self.condition_with_duration(Duration::from_millis(100), ctx, predicate)
2034    }
2035
2036    pub fn condition_with_duration(
2037        &self,
2038        duration: Duration,
2039        ctx: &TestAppContext,
2040        mut predicate: impl FnMut(&T, &AppContext) -> bool,
2041    ) -> impl Future<Output = ()> {
2042        let (tx, mut rx) = mpsc::channel(1024);
2043
2044        let mut ctx = ctx.0.borrow_mut();
2045        self.update(&mut *ctx, |_, ctx| {
2046            ctx.observe(self, {
2047                let mut tx = tx.clone();
2048                move |_, _, _| {
2049                    tx.blocking_send(()).ok();
2050                }
2051            });
2052            ctx.subscribe(self, {
2053                let mut tx = tx.clone();
2054                move |_, _, _| {
2055                    tx.blocking_send(()).ok();
2056                }
2057            })
2058        });
2059
2060        let ctx = ctx.weak_self.as_ref().unwrap().upgrade().unwrap();
2061        let handle = self.downgrade();
2062
2063        async move {
2064            timeout(duration, async move {
2065                loop {
2066                    {
2067                        let ctx = ctx.borrow();
2068                        let ctx = ctx.as_ref();
2069                        if predicate(
2070                            handle
2071                                .upgrade(ctx)
2072                                .expect("model dropped with pending condition")
2073                                .read(ctx),
2074                            ctx,
2075                        ) {
2076                            break;
2077                        }
2078                    }
2079
2080                    rx.recv()
2081                        .await
2082                        .expect("model dropped with pending condition");
2083                }
2084            })
2085            .await
2086            .expect("condition timed out");
2087        }
2088    }
2089}
2090
2091impl<T> Clone for ModelHandle<T> {
2092    fn clone(&self) -> Self {
2093        self.ref_counts.lock().inc_model(self.model_id);
2094        Self {
2095            model_id: self.model_id,
2096            model_type: PhantomData,
2097            ref_counts: self.ref_counts.clone(),
2098        }
2099    }
2100}
2101
2102impl<T> PartialEq for ModelHandle<T> {
2103    fn eq(&self, other: &Self) -> bool {
2104        self.model_id == other.model_id
2105    }
2106}
2107
2108impl<T> Eq for ModelHandle<T> {}
2109
2110impl<T> Hash for ModelHandle<T> {
2111    fn hash<H: Hasher>(&self, state: &mut H) {
2112        self.model_id.hash(state);
2113    }
2114}
2115
2116impl<T> std::borrow::Borrow<usize> for ModelHandle<T> {
2117    fn borrow(&self) -> &usize {
2118        &self.model_id
2119    }
2120}
2121
2122impl<T> Debug for ModelHandle<T> {
2123    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2124        f.debug_tuple(&format!("ModelHandle<{}>", type_name::<T>()))
2125            .field(&self.model_id)
2126            .finish()
2127    }
2128}
2129
2130unsafe impl<T> Send for ModelHandle<T> {}
2131unsafe impl<T> Sync for ModelHandle<T> {}
2132
2133impl<T> Drop for ModelHandle<T> {
2134    fn drop(&mut self) {
2135        self.ref_counts.lock().dec_model(self.model_id);
2136    }
2137}
2138
2139impl<T> Handle<T> for ModelHandle<T> {
2140    fn id(&self) -> usize {
2141        self.model_id
2142    }
2143
2144    fn location(&self) -> EntityLocation {
2145        EntityLocation::Model(self.model_id)
2146    }
2147}
2148
2149pub struct WeakModelHandle<T> {
2150    model_id: usize,
2151    model_type: PhantomData<T>,
2152}
2153
2154impl<T: Entity> WeakModelHandle<T> {
2155    fn new(model_id: usize) -> Self {
2156        Self {
2157            model_id,
2158            model_type: PhantomData,
2159        }
2160    }
2161
2162    pub fn upgrade(&self, ctx: impl AsRef<AppContext>) -> Option<ModelHandle<T>> {
2163        let ctx = ctx.as_ref();
2164        if ctx.models.contains_key(&self.model_id) {
2165            Some(ModelHandle::new(self.model_id, &ctx.ref_counts))
2166        } else {
2167            None
2168        }
2169    }
2170}
2171
2172impl<T> Clone for WeakModelHandle<T> {
2173    fn clone(&self) -> Self {
2174        Self {
2175            model_id: self.model_id,
2176            model_type: PhantomData,
2177        }
2178    }
2179}
2180
2181pub struct ViewHandle<T> {
2182    window_id: usize,
2183    view_id: usize,
2184    view_type: PhantomData<T>,
2185    ref_counts: Arc<Mutex<RefCounts>>,
2186}
2187
2188impl<T: View> ViewHandle<T> {
2189    fn new(window_id: usize, view_id: usize, ref_counts: &Arc<Mutex<RefCounts>>) -> Self {
2190        ref_counts.lock().inc_view(window_id, view_id);
2191        Self {
2192            window_id,
2193            view_id,
2194            view_type: PhantomData,
2195            ref_counts: ref_counts.clone(),
2196        }
2197    }
2198
2199    pub fn downgrade(&self) -> WeakViewHandle<T> {
2200        WeakViewHandle::new(self.window_id, self.view_id)
2201    }
2202
2203    pub fn window_id(&self) -> usize {
2204        self.window_id
2205    }
2206
2207    pub fn id(&self) -> usize {
2208        self.view_id
2209    }
2210
2211    pub fn read<'a, A: ReadView>(&self, app: &'a A) -> &'a T {
2212        app.read_view(self)
2213    }
2214
2215    pub fn read_with<A, F, S>(&self, ctx: &A, read: F) -> S
2216    where
2217        A: ReadViewWith,
2218        F: FnOnce(&T, &AppContext) -> S,
2219    {
2220        ctx.read_view_with(self, read)
2221    }
2222
2223    pub fn update<A, F, S>(&self, app: &mut A, update: F) -> S
2224    where
2225        A: UpdateView,
2226        F: FnOnce(&mut T, &mut ViewContext<T>) -> S,
2227    {
2228        app.update_view(self, update)
2229    }
2230
2231    pub fn is_focused(&self, app: &AppContext) -> bool {
2232        app.focused_view_id(self.window_id)
2233            .map_or(false, |focused_id| focused_id == self.view_id)
2234    }
2235
2236    pub fn condition(
2237        &self,
2238        ctx: &TestAppContext,
2239        predicate: impl FnMut(&T, &AppContext) -> bool,
2240    ) -> impl Future<Output = ()> {
2241        self.condition_with_duration(Duration::from_millis(500), ctx, predicate)
2242    }
2243
2244    pub fn condition_with_duration(
2245        &self,
2246        duration: Duration,
2247        ctx: &TestAppContext,
2248        mut predicate: impl FnMut(&T, &AppContext) -> bool,
2249    ) -> impl Future<Output = ()> {
2250        let (tx, mut rx) = mpsc::channel(1024);
2251
2252        let mut ctx = ctx.0.borrow_mut();
2253        self.update(&mut *ctx, |_, ctx| {
2254            ctx.observe_view(self, {
2255                let mut tx = tx.clone();
2256                move |_, _, _| {
2257                    tx.blocking_send(()).ok();
2258                }
2259            });
2260
2261            ctx.subscribe(self, {
2262                let mut tx = tx.clone();
2263                move |_, _, _| {
2264                    tx.blocking_send(()).ok();
2265                }
2266            })
2267        });
2268
2269        let ctx = ctx.weak_self.as_ref().unwrap().upgrade().unwrap();
2270        let handle = self.downgrade();
2271
2272        async move {
2273            timeout(duration, async move {
2274                loop {
2275                    {
2276                        let ctx = ctx.borrow();
2277                        let ctx = ctx.as_ref();
2278                        if predicate(
2279                            handle
2280                                .upgrade(ctx)
2281                                .expect("view dropped with pending condition")
2282                                .read(ctx),
2283                            ctx,
2284                        ) {
2285                            break;
2286                        }
2287                    }
2288
2289                    rx.recv()
2290                        .await
2291                        .expect("view dropped with pending condition");
2292                }
2293            })
2294            .await
2295            .expect("condition timed out");
2296        }
2297    }
2298}
2299
2300impl<T> Clone for ViewHandle<T> {
2301    fn clone(&self) -> Self {
2302        self.ref_counts
2303            .lock()
2304            .inc_view(self.window_id, self.view_id);
2305        Self {
2306            window_id: self.window_id,
2307            view_id: self.view_id,
2308            view_type: PhantomData,
2309            ref_counts: self.ref_counts.clone(),
2310        }
2311    }
2312}
2313
2314impl<T> PartialEq for ViewHandle<T> {
2315    fn eq(&self, other: &Self) -> bool {
2316        self.window_id == other.window_id && self.view_id == other.view_id
2317    }
2318}
2319
2320impl<T> Eq for ViewHandle<T> {}
2321
2322impl<T> Debug for ViewHandle<T> {
2323    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2324        f.debug_struct(&format!("ViewHandle<{}>", type_name::<T>()))
2325            .field("window_id", &self.window_id)
2326            .field("view_id", &self.view_id)
2327            .finish()
2328    }
2329}
2330
2331impl<T> Drop for ViewHandle<T> {
2332    fn drop(&mut self) {
2333        self.ref_counts
2334            .lock()
2335            .dec_view(self.window_id, self.view_id);
2336    }
2337}
2338
2339impl<T> Handle<T> for ViewHandle<T> {
2340    fn id(&self) -> usize {
2341        self.view_id
2342    }
2343
2344    fn location(&self) -> EntityLocation {
2345        EntityLocation::View(self.window_id, self.view_id)
2346    }
2347}
2348
2349pub struct AnyViewHandle {
2350    window_id: usize,
2351    view_id: usize,
2352    view_type: TypeId,
2353    ref_counts: Arc<Mutex<RefCounts>>,
2354}
2355
2356impl AnyViewHandle {
2357    pub fn id(&self) -> usize {
2358        self.view_id
2359    }
2360
2361    pub fn is<T: 'static>(&self) -> bool {
2362        TypeId::of::<T>() == self.view_type
2363    }
2364
2365    pub fn downcast<T: View>(self) -> Option<ViewHandle<T>> {
2366        if self.is::<T>() {
2367            let result = Some(ViewHandle {
2368                window_id: self.window_id,
2369                view_id: self.view_id,
2370                ref_counts: self.ref_counts.clone(),
2371                view_type: PhantomData,
2372            });
2373            unsafe {
2374                Arc::decrement_strong_count(&self.ref_counts);
2375            }
2376            std::mem::forget(self);
2377            result
2378        } else {
2379            None
2380        }
2381    }
2382}
2383
2384impl Clone for AnyViewHandle {
2385    fn clone(&self) -> Self {
2386        self.ref_counts
2387            .lock()
2388            .inc_view(self.window_id, self.view_id);
2389        Self {
2390            window_id: self.window_id,
2391            view_id: self.view_id,
2392            view_type: self.view_type,
2393            ref_counts: self.ref_counts.clone(),
2394        }
2395    }
2396}
2397
2398impl<T: View> From<&ViewHandle<T>> for AnyViewHandle {
2399    fn from(handle: &ViewHandle<T>) -> Self {
2400        handle
2401            .ref_counts
2402            .lock()
2403            .inc_view(handle.window_id, handle.view_id);
2404        AnyViewHandle {
2405            window_id: handle.window_id,
2406            view_id: handle.view_id,
2407            view_type: TypeId::of::<T>(),
2408            ref_counts: handle.ref_counts.clone(),
2409        }
2410    }
2411}
2412
2413impl<T: View> From<ViewHandle<T>> for AnyViewHandle {
2414    fn from(handle: ViewHandle<T>) -> Self {
2415        let any_handle = AnyViewHandle {
2416            window_id: handle.window_id,
2417            view_id: handle.view_id,
2418            view_type: TypeId::of::<T>(),
2419            ref_counts: handle.ref_counts.clone(),
2420        };
2421        unsafe {
2422            Arc::decrement_strong_count(&handle.ref_counts);
2423        }
2424        std::mem::forget(handle);
2425        any_handle
2426    }
2427}
2428
2429impl Drop for AnyViewHandle {
2430    fn drop(&mut self) {
2431        self.ref_counts
2432            .lock()
2433            .dec_view(self.window_id, self.view_id);
2434    }
2435}
2436
2437pub struct AnyModelHandle {
2438    model_id: usize,
2439    ref_counts: Arc<Mutex<RefCounts>>,
2440}
2441
2442impl<T: Entity> From<ModelHandle<T>> for AnyModelHandle {
2443    fn from(handle: ModelHandle<T>) -> Self {
2444        handle.ref_counts.lock().inc_model(handle.model_id);
2445        Self {
2446            model_id: handle.model_id,
2447            ref_counts: handle.ref_counts.clone(),
2448        }
2449    }
2450}
2451
2452impl Drop for AnyModelHandle {
2453    fn drop(&mut self) {
2454        self.ref_counts.lock().dec_model(self.model_id);
2455    }
2456}
2457pub struct WeakViewHandle<T> {
2458    window_id: usize,
2459    view_id: usize,
2460    view_type: PhantomData<T>,
2461}
2462
2463impl<T: View> WeakViewHandle<T> {
2464    fn new(window_id: usize, view_id: usize) -> Self {
2465        Self {
2466            window_id,
2467            view_id,
2468            view_type: PhantomData,
2469        }
2470    }
2471
2472    pub fn upgrade(&self, ctx: impl AsRef<AppContext>) -> Option<ViewHandle<T>> {
2473        let ctx = ctx.as_ref();
2474        if ctx.ref_counts.lock().is_entity_alive(self.view_id) {
2475            Some(ViewHandle::new(
2476                self.window_id,
2477                self.view_id,
2478                &ctx.ref_counts,
2479            ))
2480        } else {
2481            None
2482        }
2483    }
2484}
2485
2486impl<T> Clone for WeakViewHandle<T> {
2487    fn clone(&self) -> Self {
2488        Self {
2489            window_id: self.window_id,
2490            view_id: self.view_id,
2491            view_type: PhantomData,
2492        }
2493    }
2494}
2495
2496pub struct ValueHandle<T> {
2497    value_type: PhantomData<T>,
2498    tag_type_id: TypeId,
2499    id: usize,
2500    ref_counts: Weak<Mutex<RefCounts>>,
2501}
2502
2503impl<T: 'static> ValueHandle<T> {
2504    fn new(tag_type_id: TypeId, id: usize, ref_counts: &Arc<Mutex<RefCounts>>) -> Self {
2505        ref_counts.lock().inc_value(tag_type_id, id);
2506        Self {
2507            value_type: PhantomData,
2508            tag_type_id,
2509            id,
2510            ref_counts: Arc::downgrade(ref_counts),
2511        }
2512    }
2513
2514    pub fn read<R>(&self, ctx: &AppContext, f: impl FnOnce(&T) -> R) -> R {
2515        f(ctx
2516            .values
2517            .read()
2518            .get(&(self.tag_type_id, self.id))
2519            .unwrap()
2520            .downcast_ref()
2521            .unwrap())
2522    }
2523
2524    pub fn update<R>(&self, ctx: &AppContext, f: impl FnOnce(&mut T) -> R) -> R {
2525        f(ctx
2526            .values
2527            .write()
2528            .get_mut(&(self.tag_type_id, self.id))
2529            .unwrap()
2530            .downcast_mut()
2531            .unwrap())
2532    }
2533}
2534
2535impl<T> Drop for ValueHandle<T> {
2536    fn drop(&mut self) {
2537        if let Some(ref_counts) = self.ref_counts.upgrade() {
2538            ref_counts.lock().dec_value(self.tag_type_id, self.id);
2539        }
2540    }
2541}
2542
2543#[derive(Default)]
2544struct RefCounts {
2545    entity_counts: HashMap<usize, usize>,
2546    value_counts: HashMap<(TypeId, usize), usize>,
2547    dropped_models: HashSet<usize>,
2548    dropped_views: HashSet<(usize, usize)>,
2549    dropped_values: HashSet<(TypeId, usize)>,
2550}
2551
2552impl RefCounts {
2553    fn inc_model(&mut self, model_id: usize) {
2554        match self.entity_counts.entry(model_id) {
2555            Entry::Occupied(mut entry) => *entry.get_mut() += 1,
2556            Entry::Vacant(entry) => {
2557                entry.insert(1);
2558                self.dropped_models.remove(&model_id);
2559            }
2560        }
2561    }
2562
2563    fn inc_view(&mut self, window_id: usize, view_id: usize) {
2564        match self.entity_counts.entry(view_id) {
2565            Entry::Occupied(mut entry) => *entry.get_mut() += 1,
2566            Entry::Vacant(entry) => {
2567                entry.insert(1);
2568                self.dropped_views.remove(&(window_id, view_id));
2569            }
2570        }
2571    }
2572
2573    fn inc_value(&mut self, tag_type_id: TypeId, id: usize) {
2574        *self.value_counts.entry((tag_type_id, id)).or_insert(0) += 1;
2575    }
2576
2577    fn dec_model(&mut self, model_id: usize) {
2578        let count = self.entity_counts.get_mut(&model_id).unwrap();
2579        *count -= 1;
2580        if *count == 0 {
2581            self.entity_counts.remove(&model_id);
2582            self.dropped_models.insert(model_id);
2583        }
2584    }
2585
2586    fn dec_view(&mut self, window_id: usize, view_id: usize) {
2587        let count = self.entity_counts.get_mut(&view_id).unwrap();
2588        *count -= 1;
2589        if *count == 0 {
2590            self.entity_counts.remove(&view_id);
2591            self.dropped_views.insert((window_id, view_id));
2592        }
2593    }
2594
2595    fn dec_value(&mut self, tag_type_id: TypeId, id: usize) {
2596        let key = (tag_type_id, id);
2597        let count = self.value_counts.get_mut(&key).unwrap();
2598        *count -= 1;
2599        if *count == 0 {
2600            self.value_counts.remove(&key);
2601            self.dropped_values.insert(key);
2602        }
2603    }
2604
2605    fn is_entity_alive(&self, entity_id: usize) -> bool {
2606        self.entity_counts.contains_key(&entity_id)
2607    }
2608
2609    fn take_dropped(
2610        &mut self,
2611    ) -> (
2612        HashSet<usize>,
2613        HashSet<(usize, usize)>,
2614        HashSet<(TypeId, usize)>,
2615    ) {
2616        let mut dropped_models = HashSet::new();
2617        let mut dropped_views = HashSet::new();
2618        let mut dropped_values = HashSet::new();
2619        std::mem::swap(&mut self.dropped_models, &mut dropped_models);
2620        std::mem::swap(&mut self.dropped_views, &mut dropped_views);
2621        std::mem::swap(&mut self.dropped_values, &mut dropped_values);
2622        (dropped_models, dropped_views, dropped_values)
2623    }
2624}
2625
2626enum Subscription {
2627    FromModel {
2628        model_id: usize,
2629        callback: Box<dyn FnMut(&mut dyn Any, &dyn Any, &mut MutableAppContext, usize)>,
2630    },
2631    FromView {
2632        window_id: usize,
2633        view_id: usize,
2634        callback: Box<dyn FnMut(&mut dyn Any, &dyn Any, &mut MutableAppContext, usize, usize)>,
2635    },
2636}
2637
2638enum ModelObservation {
2639    FromModel {
2640        model_id: usize,
2641        callback: Box<dyn FnMut(&mut dyn Any, usize, &mut MutableAppContext, usize)>,
2642    },
2643    FromView {
2644        window_id: usize,
2645        view_id: usize,
2646        callback: Box<dyn FnMut(&mut dyn Any, usize, &mut MutableAppContext, usize, usize)>,
2647    },
2648}
2649
2650struct ViewObservation {
2651    window_id: usize,
2652    view_id: usize,
2653    callback: Box<dyn FnMut(&mut dyn Any, usize, usize, &mut MutableAppContext, usize, usize)>,
2654}
2655
2656#[cfg(test)]
2657mod tests {
2658    use super::*;
2659    use crate::elements::*;
2660    use smol::future::poll_once;
2661
2662    #[crate::test(self)]
2663    fn test_model_handles(app: &mut MutableAppContext) {
2664        struct Model {
2665            other: Option<ModelHandle<Model>>,
2666            events: Vec<String>,
2667        }
2668
2669        impl Entity for Model {
2670            type Event = usize;
2671        }
2672
2673        impl Model {
2674            fn new(other: Option<ModelHandle<Self>>, ctx: &mut ModelContext<Self>) -> Self {
2675                if let Some(other) = other.as_ref() {
2676                    ctx.observe(other, |me, _, _| {
2677                        me.events.push("notified".into());
2678                    });
2679                    ctx.subscribe(other, |me, event, _| {
2680                        me.events.push(format!("observed event {}", event));
2681                    });
2682                }
2683
2684                Self {
2685                    other,
2686                    events: Vec::new(),
2687                }
2688            }
2689        }
2690
2691        let handle_1 = app.add_model(|ctx| Model::new(None, ctx));
2692        let handle_2 = app.add_model(|ctx| Model::new(Some(handle_1.clone()), ctx));
2693        assert_eq!(app.ctx.models.len(), 2);
2694
2695        handle_1.update(app, |model, ctx| {
2696            model.events.push("updated".into());
2697            ctx.emit(1);
2698            ctx.notify();
2699            ctx.emit(2);
2700        });
2701        assert_eq!(handle_1.read(app).events, vec!["updated".to_string()]);
2702        assert_eq!(
2703            handle_2.read(app).events,
2704            vec![
2705                "observed event 1".to_string(),
2706                "notified".to_string(),
2707                "observed event 2".to_string(),
2708            ]
2709        );
2710
2711        handle_2.update(app, |model, _| {
2712            drop(handle_1);
2713            model.other.take();
2714        });
2715
2716        assert_eq!(app.ctx.models.len(), 1);
2717        assert!(app.subscriptions.is_empty());
2718        assert!(app.model_observations.is_empty());
2719    }
2720
2721    #[crate::test(self)]
2722    fn test_subscribe_and_emit_from_model(app: &mut MutableAppContext) {
2723        #[derive(Default)]
2724        struct Model {
2725            events: Vec<usize>,
2726        }
2727
2728        impl Entity for Model {
2729            type Event = usize;
2730        }
2731
2732        let handle_1 = app.add_model(|_| Model::default());
2733        let handle_2 = app.add_model(|_| Model::default());
2734        let handle_2b = handle_2.clone();
2735
2736        handle_1.update(app, |_, c| {
2737            c.subscribe(&handle_2, move |model: &mut Model, event, c| {
2738                model.events.push(*event);
2739
2740                c.subscribe(&handle_2b, |model, event, _| {
2741                    model.events.push(*event * 2);
2742                });
2743            });
2744        });
2745
2746        handle_2.update(app, |_, c| c.emit(7));
2747        assert_eq!(handle_1.read(app).events, vec![7]);
2748
2749        handle_2.update(app, |_, c| c.emit(5));
2750        assert_eq!(handle_1.read(app).events, vec![7, 10, 5]);
2751    }
2752
2753    #[crate::test(self)]
2754    fn test_observe_and_notify_from_model(app: &mut MutableAppContext) {
2755        #[derive(Default)]
2756        struct Model {
2757            count: usize,
2758            events: Vec<usize>,
2759        }
2760
2761        impl Entity for Model {
2762            type Event = ();
2763        }
2764
2765        let handle_1 = app.add_model(|_| Model::default());
2766        let handle_2 = app.add_model(|_| Model::default());
2767        let handle_2b = handle_2.clone();
2768
2769        handle_1.update(app, |_, c| {
2770            c.observe(&handle_2, move |model, observed, c| {
2771                model.events.push(observed.read(c).count);
2772                c.observe(&handle_2b, |model, observed, c| {
2773                    model.events.push(observed.read(c).count * 2);
2774                });
2775            });
2776        });
2777
2778        handle_2.update(app, |model, c| {
2779            model.count = 7;
2780            c.notify()
2781        });
2782        assert_eq!(handle_1.read(app).events, vec![7]);
2783
2784        handle_2.update(app, |model, c| {
2785            model.count = 5;
2786            c.notify()
2787        });
2788        assert_eq!(handle_1.read(app).events, vec![7, 10, 5])
2789    }
2790
2791    #[crate::test(self)]
2792    fn test_view_handles(app: &mut MutableAppContext) {
2793        struct View {
2794            other: Option<ViewHandle<View>>,
2795            events: Vec<String>,
2796        }
2797
2798        impl Entity for View {
2799            type Event = usize;
2800        }
2801
2802        impl super::View for View {
2803            fn render<'a>(&self, _: &AppContext) -> ElementBox {
2804                Empty::new().boxed()
2805            }
2806
2807            fn ui_name() -> &'static str {
2808                "View"
2809            }
2810        }
2811
2812        impl View {
2813            fn new(other: Option<ViewHandle<View>>, ctx: &mut ViewContext<Self>) -> Self {
2814                if let Some(other) = other.as_ref() {
2815                    ctx.subscribe_to_view(other, |me, _, event, _| {
2816                        me.events.push(format!("observed event {}", event));
2817                    });
2818                }
2819                Self {
2820                    other,
2821                    events: Vec::new(),
2822                }
2823            }
2824        }
2825
2826        let (window_id, _) = app.add_window(|ctx| View::new(None, ctx));
2827        let handle_1 = app.add_view(window_id, |ctx| View::new(None, ctx));
2828        let handle_2 = app.add_view(window_id, |ctx| View::new(Some(handle_1.clone()), ctx));
2829        assert_eq!(app.ctx.views.len(), 3);
2830
2831        handle_1.update(app, |view, ctx| {
2832            view.events.push("updated".into());
2833            ctx.emit(1);
2834            ctx.emit(2);
2835        });
2836        assert_eq!(handle_1.read(app).events, vec!["updated".to_string()]);
2837        assert_eq!(
2838            handle_2.read(app).events,
2839            vec![
2840                "observed event 1".to_string(),
2841                "observed event 2".to_string(),
2842            ]
2843        );
2844
2845        handle_2.update(app, |view, _| {
2846            drop(handle_1);
2847            view.other.take();
2848        });
2849
2850        assert_eq!(app.ctx.views.len(), 2);
2851        assert!(app.subscriptions.is_empty());
2852        assert!(app.model_observations.is_empty());
2853    }
2854
2855    #[crate::test(self)]
2856    fn test_subscribe_and_emit_from_view(app: &mut MutableAppContext) {
2857        #[derive(Default)]
2858        struct View {
2859            events: Vec<usize>,
2860        }
2861
2862        impl Entity for View {
2863            type Event = usize;
2864        }
2865
2866        impl super::View for View {
2867            fn render<'a>(&self, _: &AppContext) -> ElementBox {
2868                Empty::new().boxed()
2869            }
2870
2871            fn ui_name() -> &'static str {
2872                "View"
2873            }
2874        }
2875
2876        struct Model;
2877
2878        impl Entity for Model {
2879            type Event = usize;
2880        }
2881
2882        let (window_id, handle_1) = app.add_window(|_| View::default());
2883        let handle_2 = app.add_view(window_id, |_| View::default());
2884        let handle_2b = handle_2.clone();
2885        let handle_3 = app.add_model(|_| Model);
2886
2887        handle_1.update(app, |_, c| {
2888            c.subscribe_to_view(&handle_2, move |me, _, event, c| {
2889                me.events.push(*event);
2890
2891                c.subscribe_to_view(&handle_2b, |me, _, event, _| {
2892                    me.events.push(*event * 2);
2893                });
2894            });
2895
2896            c.subscribe_to_model(&handle_3, |me, _, event, _| {
2897                me.events.push(*event);
2898            })
2899        });
2900
2901        handle_2.update(app, |_, c| c.emit(7));
2902        assert_eq!(handle_1.read(app).events, vec![7]);
2903
2904        handle_2.update(app, |_, c| c.emit(5));
2905        assert_eq!(handle_1.read(app).events, vec![7, 10, 5]);
2906
2907        handle_3.update(app, |_, c| c.emit(9));
2908        assert_eq!(handle_1.read(app).events, vec![7, 10, 5, 9]);
2909    }
2910
2911    #[crate::test(self)]
2912    fn test_dropping_subscribers(app: &mut MutableAppContext) {
2913        struct View;
2914
2915        impl Entity for View {
2916            type Event = ();
2917        }
2918
2919        impl super::View for View {
2920            fn render<'a>(&self, _: &AppContext) -> ElementBox {
2921                Empty::new().boxed()
2922            }
2923
2924            fn ui_name() -> &'static str {
2925                "View"
2926            }
2927        }
2928
2929        struct Model;
2930
2931        impl Entity for Model {
2932            type Event = ();
2933        }
2934
2935        let (window_id, _) = app.add_window(|_| View);
2936        let observing_view = app.add_view(window_id, |_| View);
2937        let emitting_view = app.add_view(window_id, |_| View);
2938        let observing_model = app.add_model(|_| Model);
2939        let observed_model = app.add_model(|_| Model);
2940
2941        observing_view.update(app, |_, ctx| {
2942            ctx.subscribe_to_view(&emitting_view, |_, _, _, _| {});
2943            ctx.subscribe_to_model(&observed_model, |_, _, _, _| {});
2944        });
2945        observing_model.update(app, |_, ctx| {
2946            ctx.subscribe(&observed_model, |_, _, _| {});
2947        });
2948
2949        app.update(|| {
2950            drop(observing_view);
2951            drop(observing_model);
2952        });
2953
2954        emitting_view.update(app, |_, ctx| ctx.emit(()));
2955        observed_model.update(app, |_, ctx| ctx.emit(()));
2956    }
2957
2958    #[crate::test(self)]
2959    fn test_observe_and_notify_from_view(app: &mut MutableAppContext) {
2960        #[derive(Default)]
2961        struct View {
2962            events: Vec<usize>,
2963        }
2964
2965        impl Entity for View {
2966            type Event = usize;
2967        }
2968
2969        impl super::View for View {
2970            fn render<'a>(&self, _: &AppContext) -> ElementBox {
2971                Empty::new().boxed()
2972            }
2973
2974            fn ui_name() -> &'static str {
2975                "View"
2976            }
2977        }
2978
2979        #[derive(Default)]
2980        struct Model {
2981            count: usize,
2982        }
2983
2984        impl Entity for Model {
2985            type Event = ();
2986        }
2987
2988        let (_, view) = app.add_window(|_| View::default());
2989        let model = app.add_model(|_| Model::default());
2990
2991        view.update(app, |_, c| {
2992            c.observe_model(&model, |me, observed, c| {
2993                me.events.push(observed.read(c).count)
2994            });
2995        });
2996
2997        model.update(app, |model, c| {
2998            model.count = 11;
2999            c.notify();
3000        });
3001        assert_eq!(view.read(app).events, vec![11]);
3002    }
3003
3004    #[crate::test(self)]
3005    fn test_dropping_observers(app: &mut MutableAppContext) {
3006        struct View;
3007
3008        impl Entity for View {
3009            type Event = ();
3010        }
3011
3012        impl super::View for View {
3013            fn render<'a>(&self, _: &AppContext) -> ElementBox {
3014                Empty::new().boxed()
3015            }
3016
3017            fn ui_name() -> &'static str {
3018                "View"
3019            }
3020        }
3021
3022        struct Model;
3023
3024        impl Entity for Model {
3025            type Event = ();
3026        }
3027
3028        let (window_id, _) = app.add_window(|_| View);
3029        let observing_view = app.add_view(window_id, |_| View);
3030        let observing_model = app.add_model(|_| Model);
3031        let observed_model = app.add_model(|_| Model);
3032
3033        observing_view.update(app, |_, ctx| {
3034            ctx.observe_model(&observed_model, |_, _, _| {});
3035        });
3036        observing_model.update(app, |_, ctx| {
3037            ctx.observe(&observed_model, |_, _, _| {});
3038        });
3039
3040        app.update(|| {
3041            drop(observing_view);
3042            drop(observing_model);
3043        });
3044
3045        observed_model.update(app, |_, ctx| ctx.notify());
3046    }
3047
3048    #[crate::test(self)]
3049    fn test_focus(app: &mut MutableAppContext) {
3050        struct View {
3051            name: String,
3052            events: Arc<Mutex<Vec<String>>>,
3053        }
3054
3055        impl Entity for View {
3056            type Event = ();
3057        }
3058
3059        impl super::View for View {
3060            fn render<'a>(&self, _: &AppContext) -> ElementBox {
3061                Empty::new().boxed()
3062            }
3063
3064            fn ui_name() -> &'static str {
3065                "View"
3066            }
3067
3068            fn on_focus(&mut self, _: &mut ViewContext<Self>) {
3069                self.events.lock().push(format!("{} focused", &self.name));
3070            }
3071
3072            fn on_blur(&mut self, _: &mut ViewContext<Self>) {
3073                self.events.lock().push(format!("{} blurred", &self.name));
3074            }
3075        }
3076
3077        let events: Arc<Mutex<Vec<String>>> = Default::default();
3078        let (window_id, view_1) = app.add_window(|_| View {
3079            events: events.clone(),
3080            name: "view 1".to_string(),
3081        });
3082        let view_2 = app.add_view(window_id, |_| View {
3083            events: events.clone(),
3084            name: "view 2".to_string(),
3085        });
3086
3087        view_1.update(app, |_, ctx| ctx.focus(&view_2));
3088        view_1.update(app, |_, ctx| ctx.focus(&view_1));
3089        view_1.update(app, |_, ctx| ctx.focus(&view_2));
3090        view_1.update(app, |_, _| drop(view_2));
3091
3092        assert_eq!(
3093            *events.lock(),
3094            [
3095                "view 1 focused".to_string(),
3096                "view 1 blurred".to_string(),
3097                "view 2 focused".to_string(),
3098                "view 2 blurred".to_string(),
3099                "view 1 focused".to_string(),
3100                "view 1 blurred".to_string(),
3101                "view 2 focused".to_string(),
3102                "view 1 focused".to_string(),
3103            ],
3104        );
3105    }
3106
3107    #[crate::test(self)]
3108    fn test_dispatch_action(app: &mut MutableAppContext) {
3109        struct ViewA {
3110            id: usize,
3111        }
3112
3113        impl Entity for ViewA {
3114            type Event = ();
3115        }
3116
3117        impl View for ViewA {
3118            fn render<'a>(&self, _: &AppContext) -> ElementBox {
3119                Empty::new().boxed()
3120            }
3121
3122            fn ui_name() -> &'static str {
3123                "View"
3124            }
3125        }
3126
3127        struct ViewB {
3128            id: usize,
3129        }
3130
3131        impl Entity for ViewB {
3132            type Event = ();
3133        }
3134
3135        impl View for ViewB {
3136            fn render<'a>(&self, _: &AppContext) -> ElementBox {
3137                Empty::new().boxed()
3138            }
3139
3140            fn ui_name() -> &'static str {
3141                "View"
3142            }
3143        }
3144
3145        struct ActionArg {
3146            foo: String,
3147        }
3148
3149        let actions = Rc::new(RefCell::new(Vec::new()));
3150
3151        let actions_clone = actions.clone();
3152        app.add_global_action("action", move |_: &ActionArg, _: &mut MutableAppContext| {
3153            actions_clone.borrow_mut().push("global a".to_string());
3154        });
3155
3156        let actions_clone = actions.clone();
3157        app.add_global_action("action", move |_: &ActionArg, _: &mut MutableAppContext| {
3158            actions_clone.borrow_mut().push("global b".to_string());
3159        });
3160
3161        let actions_clone = actions.clone();
3162        app.add_action("action", move |view: &mut ViewA, arg: &ActionArg, ctx| {
3163            assert_eq!(arg.foo, "bar");
3164            ctx.propagate_action();
3165            actions_clone.borrow_mut().push(format!("{} a", view.id));
3166        });
3167
3168        let actions_clone = actions.clone();
3169        app.add_action("action", move |view: &mut ViewA, _: &ActionArg, ctx| {
3170            if view.id != 1 {
3171                ctx.propagate_action();
3172            }
3173            actions_clone.borrow_mut().push(format!("{} b", view.id));
3174        });
3175
3176        let actions_clone = actions.clone();
3177        app.add_action("action", move |view: &mut ViewB, _: &ActionArg, ctx| {
3178            ctx.propagate_action();
3179            actions_clone.borrow_mut().push(format!("{} c", view.id));
3180        });
3181
3182        let actions_clone = actions.clone();
3183        app.add_action("action", move |view: &mut ViewB, _: &ActionArg, ctx| {
3184            ctx.propagate_action();
3185            actions_clone.borrow_mut().push(format!("{} d", view.id));
3186        });
3187
3188        let (window_id, view_1) = app.add_window(|_| ViewA { id: 1 });
3189        let view_2 = app.add_view(window_id, |_| ViewB { id: 2 });
3190        let view_3 = app.add_view(window_id, |_| ViewA { id: 3 });
3191        let view_4 = app.add_view(window_id, |_| ViewB { id: 4 });
3192
3193        app.dispatch_action(
3194            window_id,
3195            vec![view_1.id(), view_2.id(), view_3.id(), view_4.id()],
3196            "action",
3197            ActionArg { foo: "bar".into() },
3198        );
3199
3200        assert_eq!(
3201            *actions.borrow(),
3202            vec!["4 d", "4 c", "3 b", "3 a", "2 d", "2 c", "1 b"]
3203        );
3204
3205        // Remove view_1, which doesn't propagate the action
3206        actions.borrow_mut().clear();
3207        app.dispatch_action(
3208            window_id,
3209            vec![view_2.id(), view_3.id(), view_4.id()],
3210            "action",
3211            ActionArg { foo: "bar".into() },
3212        );
3213
3214        assert_eq!(
3215            *actions.borrow(),
3216            vec!["4 d", "4 c", "3 b", "3 a", "2 d", "2 c", "global b", "global a"]
3217        );
3218    }
3219
3220    #[crate::test(self)]
3221    fn test_dispatch_keystroke(app: &mut MutableAppContext) {
3222        use std::cell::Cell;
3223
3224        #[derive(Clone)]
3225        struct ActionArg {
3226            key: String,
3227        }
3228
3229        struct View {
3230            id: usize,
3231            keymap_context: keymap::Context,
3232        }
3233
3234        impl Entity for View {
3235            type Event = ();
3236        }
3237
3238        impl super::View for View {
3239            fn render<'a>(&self, _: &AppContext) -> ElementBox {
3240                Empty::new().boxed()
3241            }
3242
3243            fn ui_name() -> &'static str {
3244                "View"
3245            }
3246
3247            fn keymap_context(&self, _: &AppContext) -> keymap::Context {
3248                self.keymap_context.clone()
3249            }
3250        }
3251
3252        impl View {
3253            fn new(id: usize) -> Self {
3254                View {
3255                    id,
3256                    keymap_context: keymap::Context::default(),
3257                }
3258            }
3259        }
3260
3261        let mut view_1 = View::new(1);
3262        let mut view_2 = View::new(2);
3263        let mut view_3 = View::new(3);
3264        view_1.keymap_context.set.insert("a".into());
3265        view_2.keymap_context.set.insert("b".into());
3266        view_3.keymap_context.set.insert("c".into());
3267
3268        let (window_id, view_1) = app.add_window(|_| view_1);
3269        let view_2 = app.add_view(window_id, |_| view_2);
3270        let view_3 = app.add_view(window_id, |_| view_3);
3271
3272        // This keymap's only binding dispatches an action on view 2 because that view will have
3273        // "a" and "b" in its context, but not "c".
3274        let binding = keymap::Binding::new("a", "action", Some("a && b && !c"))
3275            .with_arg(ActionArg { key: "a".into() });
3276        app.add_bindings(vec![binding]);
3277
3278        let handled_action = Rc::new(Cell::new(false));
3279        let handled_action_clone = handled_action.clone();
3280        app.add_action("action", move |view: &mut View, arg: &ActionArg, _ctx| {
3281            handled_action_clone.set(true);
3282            assert_eq!(view.id, 2);
3283            assert_eq!(arg.key, "a");
3284        });
3285
3286        app.dispatch_keystroke(
3287            window_id,
3288            vec![view_1.id(), view_2.id(), view_3.id()],
3289            &Keystroke::parse("a").unwrap(),
3290        )
3291        .unwrap();
3292
3293        assert!(handled_action.get());
3294    }
3295
3296    #[crate::test(self)]
3297    async fn test_model_condition(mut app: TestAppContext) {
3298        struct Counter(usize);
3299
3300        impl super::Entity for Counter {
3301            type Event = ();
3302        }
3303
3304        impl Counter {
3305            fn inc(&mut self, ctx: &mut ModelContext<Self>) {
3306                self.0 += 1;
3307                ctx.notify();
3308            }
3309        }
3310
3311        let model = app.add_model(|_| Counter(0));
3312
3313        let condition1 = model.condition(&app, |model, _| model.0 == 2);
3314        let condition2 = model.condition(&app, |model, _| model.0 == 3);
3315        smol::pin!(condition1, condition2);
3316
3317        model.update(&mut app, |model, ctx| model.inc(ctx));
3318        assert_eq!(poll_once(&mut condition1).await, None);
3319        assert_eq!(poll_once(&mut condition2).await, None);
3320
3321        model.update(&mut app, |model, ctx| model.inc(ctx));
3322        assert_eq!(poll_once(&mut condition1).await, Some(()));
3323        assert_eq!(poll_once(&mut condition2).await, None);
3324
3325        model.update(&mut app, |model, ctx| model.inc(ctx));
3326        assert_eq!(poll_once(&mut condition2).await, Some(()));
3327
3328        model.update(&mut app, |_, ctx| ctx.notify());
3329    }
3330
3331    #[crate::test(self)]
3332    #[should_panic]
3333    async fn test_model_condition_timeout(mut app: TestAppContext) {
3334        struct Model;
3335
3336        impl super::Entity for Model {
3337            type Event = ();
3338        }
3339
3340        let model = app.add_model(|_| Model);
3341        model.condition(&app, |_, _| false).await;
3342    }
3343
3344    #[crate::test(self)]
3345    #[should_panic(expected = "model dropped with pending condition")]
3346    async fn test_model_condition_panic_on_drop(mut app: TestAppContext) {
3347        struct Model;
3348
3349        impl super::Entity for Model {
3350            type Event = ();
3351        }
3352
3353        let model = app.add_model(|_| Model);
3354        let condition = model.condition(&app, |_, _| false);
3355        app.update(|_| drop(model));
3356        condition.await;
3357    }
3358
3359    #[crate::test(self)]
3360    async fn test_view_condition(mut app: TestAppContext) {
3361        struct Counter(usize);
3362
3363        impl super::Entity for Counter {
3364            type Event = ();
3365        }
3366
3367        impl super::View for Counter {
3368            fn ui_name() -> &'static str {
3369                "test view"
3370            }
3371
3372            fn render(&self, _: &AppContext) -> ElementBox {
3373                Empty::new().boxed()
3374            }
3375        }
3376
3377        impl Counter {
3378            fn inc(&mut self, ctx: &mut ViewContext<Self>) {
3379                self.0 += 1;
3380                ctx.notify();
3381            }
3382        }
3383
3384        let (_, view) = app.add_window(|_| Counter(0));
3385
3386        let condition1 = view.condition(&app, |view, _| view.0 == 2);
3387        let condition2 = view.condition(&app, |view, _| view.0 == 3);
3388        smol::pin!(condition1, condition2);
3389
3390        view.update(&mut app, |view, ctx| view.inc(ctx));
3391        assert_eq!(poll_once(&mut condition1).await, None);
3392        assert_eq!(poll_once(&mut condition2).await, None);
3393
3394        view.update(&mut app, |view, ctx| view.inc(ctx));
3395        assert_eq!(poll_once(&mut condition1).await, Some(()));
3396        assert_eq!(poll_once(&mut condition2).await, None);
3397
3398        view.update(&mut app, |view, ctx| view.inc(ctx));
3399        assert_eq!(poll_once(&mut condition2).await, Some(()));
3400        view.update(&mut app, |_, ctx| ctx.notify());
3401    }
3402
3403    #[crate::test(self)]
3404    #[should_panic]
3405    async fn test_view_condition_timeout(mut app: TestAppContext) {
3406        struct View;
3407
3408        impl super::Entity for View {
3409            type Event = ();
3410        }
3411
3412        impl super::View for View {
3413            fn ui_name() -> &'static str {
3414                "test view"
3415            }
3416
3417            fn render(&self, _: &AppContext) -> ElementBox {
3418                Empty::new().boxed()
3419            }
3420        }
3421
3422        let (_, view) = app.add_window(|_| View);
3423        view.condition(&app, |_, _| false).await;
3424    }
3425
3426    #[crate::test(self)]
3427    #[should_panic(expected = "view dropped with pending condition")]
3428    async fn test_view_condition_panic_on_drop(mut app: TestAppContext) {
3429        struct View;
3430
3431        impl super::Entity for View {
3432            type Event = ();
3433        }
3434
3435        impl super::View for View {
3436            fn ui_name() -> &'static str {
3437                "test view"
3438            }
3439
3440            fn render(&self, _: &AppContext) -> ElementBox {
3441                Empty::new().boxed()
3442            }
3443        }
3444
3445        let window_id = app.add_window(|_| View).0;
3446        let view = app.add_view(window_id, |_| View);
3447
3448        let condition = view.condition(&app, |_, _| false);
3449        app.update(|_| drop(view));
3450        condition.await;
3451    }
3452
3453    // #[crate::test(self)]
3454    // fn test_ui_and_window_updates() {
3455    //     struct View {
3456    //         count: usize,
3457    //     }
3458
3459    //     impl Entity for View {
3460    //         type Event = ();
3461    //     }
3462
3463    //     impl super::View for View {
3464    //         fn render<'a>(&self, _: &AppContext) -> ElementBox {
3465    //             Empty::new().boxed()
3466    //         }
3467
3468    //         fn ui_name() -> &'static str {
3469    //             "View"
3470    //         }
3471    //     }
3472
3473    //     App::test(|app| async move {
3474    //         let (window_id, _) = app.add_window(|_| View { count: 3 });
3475    //         let view_1 = app.add_view(window_id, |_| View { count: 1 });
3476    //         let view_2 = app.add_view(window_id, |_| View { count: 2 });
3477
3478    //         // Ensure that registering for UI updates after mutating the app still gives us all the
3479    //         // updates.
3480    //         let ui_updates = Rc::new(RefCell::new(Vec::new()));
3481    //         let ui_updates_ = ui_updates.clone();
3482    //         app.on_ui_update(move |update, _| ui_updates_.borrow_mut().push(update));
3483
3484    //         assert_eq!(
3485    //             ui_updates.borrow_mut().drain(..).collect::<Vec<_>>(),
3486    //             vec![UiUpdate::OpenWindow {
3487    //                 window_id,
3488    //                 width: 1024.0,
3489    //                 height: 768.0,
3490    //             }]
3491    //         );
3492
3493    //         let window_invalidations = Rc::new(RefCell::new(Vec::new()));
3494    //         let window_invalidations_ = window_invalidations.clone();
3495    //         app.on_window_invalidated(window_id, move |update, _| {
3496    //             window_invalidations_.borrow_mut().push(update)
3497    //         });
3498
3499    //         let view_2_id = view_2.id();
3500    //         view_1.update(app, |view, ctx| {
3501    //             view.count = 7;
3502    //             ctx.notify();
3503    //             drop(view_2);
3504    //         });
3505
3506    //         let invalidation = window_invalidations.borrow_mut().drain(..).next().unwrap();
3507    //         assert_eq!(invalidation.updated.len(), 1);
3508    //         assert!(invalidation.updated.contains(&view_1.id()));
3509    //         assert_eq!(invalidation.removed, vec![view_2_id]);
3510
3511    //         let view_3 = view_1.update(app, |_, ctx| ctx.add_view(|_| View { count: 8 }));
3512
3513    //         let invalidation = window_invalidations.borrow_mut().drain(..).next().unwrap();
3514    //         assert_eq!(invalidation.updated.len(), 1);
3515    //         assert!(invalidation.updated.contains(&view_3.id()));
3516    //         assert!(invalidation.removed.is_empty());
3517
3518    //         view_3
3519    //             .update(app, |_, ctx| {
3520    //                 ctx.spawn_local(async { 9 }, |me, output, ctx| {
3521    //                     me.count = output;
3522    //                     ctx.notify();
3523    //                 })
3524    //             })
3525    //             .await;
3526
3527    //         let invalidation = window_invalidations.borrow_mut().drain(..).next().unwrap();
3528    //         assert_eq!(invalidation.updated.len(), 1);
3529    //         assert!(invalidation.updated.contains(&view_3.id()));
3530    //         assert!(invalidation.removed.is_empty());
3531    //     });
3532    // }
3533}