pane.rs

  1use super::{ItemViewHandle, SplitDirection};
  2use crate::{ItemHandle, ItemView, Settings, WeakItemViewHandle, Workspace};
  3use collections::{HashMap, VecDeque};
  4use gpui::{
  5    action,
  6    elements::*,
  7    geometry::{rect::RectF, vector::vec2f},
  8    keymap::Binding,
  9    platform::CursorStyle,
 10    AnyViewHandle, Entity, MutableAppContext, Quad, RenderContext, Task, View, ViewContext,
 11    ViewHandle,
 12};
 13use postage::watch;
 14use project::ProjectPath;
 15use std::{
 16    any::{Any, TypeId},
 17    cell::RefCell,
 18    cmp, mem,
 19    rc::Rc,
 20};
 21use util::ResultExt;
 22
 23action!(Split, SplitDirection);
 24action!(ActivateItem, usize);
 25action!(ActivatePrevItem);
 26action!(ActivateNextItem);
 27action!(CloseActiveItem);
 28action!(CloseInactiveItems);
 29action!(CloseItem, usize);
 30action!(GoBack);
 31action!(GoForward);
 32
 33const MAX_NAVIGATION_HISTORY_LEN: usize = 1024;
 34
 35pub fn init(cx: &mut MutableAppContext) {
 36    cx.add_action(|pane: &mut Pane, action: &ActivateItem, cx| {
 37        pane.activate_item(action.0, cx);
 38    });
 39    cx.add_action(|pane: &mut Pane, _: &ActivatePrevItem, cx| {
 40        pane.activate_prev_item(cx);
 41    });
 42    cx.add_action(|pane: &mut Pane, _: &ActivateNextItem, cx| {
 43        pane.activate_next_item(cx);
 44    });
 45    cx.add_action(|pane: &mut Pane, _: &CloseActiveItem, cx| {
 46        pane.close_active_item(cx);
 47    });
 48    cx.add_action(|pane: &mut Pane, _: &CloseInactiveItems, cx| {
 49        pane.close_inactive_items(cx);
 50    });
 51    cx.add_action(|pane: &mut Pane, action: &CloseItem, cx| {
 52        pane.close_item(action.0, cx);
 53    });
 54    cx.add_action(|pane: &mut Pane, action: &Split, cx| {
 55        pane.split(action.0, cx);
 56    });
 57    cx.add_action(|workspace: &mut Workspace, _: &GoBack, cx| {
 58        Pane::go_back(workspace, cx).detach();
 59    });
 60    cx.add_action(|workspace: &mut Workspace, _: &GoForward, cx| {
 61        Pane::go_forward(workspace, cx).detach();
 62    });
 63
 64    cx.add_bindings(vec![
 65        Binding::new("shift-cmd-{", ActivatePrevItem, Some("Pane")),
 66        Binding::new("shift-cmd-}", ActivateNextItem, Some("Pane")),
 67        Binding::new("cmd-w", CloseActiveItem, Some("Pane")),
 68        Binding::new("alt-cmd-w", CloseInactiveItems, Some("Pane")),
 69        Binding::new("cmd-k up", Split(SplitDirection::Up), Some("Pane")),
 70        Binding::new("cmd-k down", Split(SplitDirection::Down), Some("Pane")),
 71        Binding::new("cmd-k left", Split(SplitDirection::Left), Some("Pane")),
 72        Binding::new("cmd-k right", Split(SplitDirection::Right), Some("Pane")),
 73        Binding::new("ctrl--", GoBack, Some("Pane")),
 74        Binding::new("shift-ctrl-_", GoForward, Some("Pane")),
 75    ]);
 76}
 77
 78pub enum Event {
 79    Activate,
 80    Remove,
 81    Split(SplitDirection),
 82}
 83
 84pub struct Pane {
 85    item_views: Vec<(usize, Box<dyn ItemViewHandle>)>,
 86    active_item_index: usize,
 87    settings: watch::Receiver<Settings>,
 88    nav_history: Rc<RefCell<NavHistory>>,
 89    toolbars: HashMap<TypeId, Box<dyn ToolbarHandle>>,
 90    active_toolbar_type: Option<TypeId>,
 91    active_toolbar_visible: bool,
 92}
 93
 94pub trait Toolbar: View {
 95    fn active_item_changed(
 96        &mut self,
 97        item: Option<Box<dyn ItemViewHandle>>,
 98        cx: &mut ViewContext<Self>,
 99    ) -> bool;
100    fn on_dismiss(&mut self, cx: &mut ViewContext<Self>);
101}
102
103trait ToolbarHandle {
104    fn active_item_changed(
105        &self,
106        item: Option<Box<dyn ItemViewHandle>>,
107        cx: &mut MutableAppContext,
108    ) -> bool;
109    fn on_dismiss(&self, cx: &mut MutableAppContext);
110    fn to_any(&self) -> AnyViewHandle;
111}
112
113pub struct ItemNavHistory {
114    history: Rc<RefCell<NavHistory>>,
115    item_view: Rc<dyn WeakItemViewHandle>,
116}
117
118#[derive(Default)]
119pub struct NavHistory {
120    mode: NavigationMode,
121    backward_stack: VecDeque<NavigationEntry>,
122    forward_stack: VecDeque<NavigationEntry>,
123    paths_by_item: HashMap<usize, ProjectPath>,
124}
125
126#[derive(Copy, Clone)]
127enum NavigationMode {
128    Normal,
129    GoingBack,
130    GoingForward,
131    Disabled,
132}
133
134impl Default for NavigationMode {
135    fn default() -> Self {
136        Self::Normal
137    }
138}
139
140pub struct NavigationEntry {
141    pub item_view: Rc<dyn WeakItemViewHandle>,
142    pub data: Option<Box<dyn Any>>,
143}
144
145impl Pane {
146    pub fn new(settings: watch::Receiver<Settings>) -> Self {
147        Self {
148            item_views: Vec::new(),
149            active_item_index: 0,
150            settings,
151            nav_history: Default::default(),
152            toolbars: Default::default(),
153            active_toolbar_type: Default::default(),
154            active_toolbar_visible: false,
155        }
156    }
157
158    pub fn nav_history(&self) -> &Rc<RefCell<NavHistory>> {
159        &self.nav_history
160    }
161
162    pub fn activate(&self, cx: &mut ViewContext<Self>) {
163        cx.emit(Event::Activate);
164    }
165
166    pub fn go_back(workspace: &mut Workspace, cx: &mut ViewContext<Workspace>) -> Task<()> {
167        Self::navigate_history(
168            workspace,
169            workspace.active_pane().clone(),
170            NavigationMode::GoingBack,
171            cx,
172        )
173    }
174
175    pub fn go_forward(workspace: &mut Workspace, cx: &mut ViewContext<Workspace>) -> Task<()> {
176        Self::navigate_history(
177            workspace,
178            workspace.active_pane().clone(),
179            NavigationMode::GoingForward,
180            cx,
181        )
182    }
183
184    fn navigate_history(
185        workspace: &mut Workspace,
186        pane: ViewHandle<Pane>,
187        mode: NavigationMode,
188        cx: &mut ViewContext<Workspace>,
189    ) -> Task<()> {
190        let to_load = pane.update(cx, |pane, cx| {
191            // Retrieve the weak item handle from the history.
192            let entry = pane.nav_history.borrow_mut().pop(mode)?;
193
194            // If the item is still present in this pane, then activate it.
195            if let Some(index) = entry
196                .item_view
197                .upgrade(cx)
198                .and_then(|v| pane.index_for_item_view(v.as_ref()))
199            {
200                if let Some(item_view) = pane.active_item() {
201                    pane.nav_history.borrow_mut().set_mode(mode);
202                    item_view.deactivated(cx);
203                    pane.nav_history
204                        .borrow_mut()
205                        .set_mode(NavigationMode::Normal);
206                }
207
208                pane.active_item_index = index;
209                pane.focus_active_item(cx);
210                if let Some(data) = entry.data {
211                    pane.active_item()?.navigate(data, cx);
212                }
213                cx.notify();
214                None
215            }
216            // If the item is no longer present in this pane, then retrieve its
217            // project path in order to reopen it.
218            else {
219                pane.nav_history
220                    .borrow_mut()
221                    .paths_by_item
222                    .get(&entry.item_view.id())
223                    .cloned()
224                    .map(|project_path| (project_path, entry))
225            }
226        });
227
228        if let Some((project_path, entry)) = to_load {
229            // If the item was no longer present, then load it again from its previous path.
230            let pane = pane.downgrade();
231            let task = workspace.load_path(project_path, cx);
232            cx.spawn(|workspace, mut cx| async move {
233                let item = task.await;
234                if let Some(pane) = pane.upgrade(&cx) {
235                    if let Some(item) = item.log_err() {
236                        workspace.update(&mut cx, |workspace, cx| {
237                            pane.update(cx, |p, _| p.nav_history.borrow_mut().set_mode(mode));
238                            let item_view = workspace.open_item_in_pane(item, &pane, cx);
239                            pane.update(cx, |p, _| {
240                                p.nav_history.borrow_mut().set_mode(NavigationMode::Normal)
241                            });
242
243                            if let Some(data) = entry.data {
244                                item_view.navigate(data, cx);
245                            }
246                        });
247                    } else {
248                        workspace
249                            .update(&mut cx, |workspace, cx| {
250                                Self::navigate_history(workspace, pane, mode, cx)
251                            })
252                            .await;
253                    }
254                }
255            })
256        } else {
257            Task::ready(())
258        }
259    }
260
261    pub fn open_item<T>(
262        &mut self,
263        item_handle: T,
264        workspace: &Workspace,
265        cx: &mut ViewContext<Self>,
266    ) -> Box<dyn ItemViewHandle>
267    where
268        T: 'static + ItemHandle,
269    {
270        for (ix, (item_id, item_view)) in self.item_views.iter().enumerate() {
271            if *item_id == item_handle.id() {
272                let item_view = item_view.boxed_clone();
273                self.activate_item(ix, cx);
274                return item_view;
275            }
276        }
277
278        let item_view =
279            item_handle.add_view(cx.window_id(), workspace, self.nav_history.clone(), cx);
280        self.add_item_view(item_view.boxed_clone(), cx);
281        item_view
282    }
283
284    pub fn add_item_view(
285        &mut self,
286        mut item_view: Box<dyn ItemViewHandle>,
287        cx: &mut ViewContext<Self>,
288    ) {
289        item_view.added_to_pane(cx);
290        let item_idx = cmp::min(self.active_item_index + 1, self.item_views.len());
291        self.item_views
292            .insert(item_idx, (item_view.item(cx).id(), item_view));
293        self.activate_item(item_idx, cx);
294        cx.notify();
295    }
296
297    pub fn contains_item(&self, item: &dyn ItemHandle) -> bool {
298        let item_id = item.id();
299        self.item_views
300            .iter()
301            .any(|(existing_item_id, _)| *existing_item_id == item_id)
302    }
303
304    pub fn item_views(&self) -> impl Iterator<Item = &Box<dyn ItemViewHandle>> {
305        self.item_views.iter().map(|(_, view)| view)
306    }
307
308    pub fn active_item(&self) -> Option<Box<dyn ItemViewHandle>> {
309        self.item_views
310            .get(self.active_item_index)
311            .map(|(_, view)| view.clone())
312    }
313
314    pub fn index_for_item_view(&self, item_view: &dyn ItemViewHandle) -> Option<usize> {
315        self.item_views
316            .iter()
317            .position(|(_, i)| i.id() == item_view.id())
318    }
319
320    pub fn index_for_item(&self, item: &dyn ItemHandle) -> Option<usize> {
321        self.item_views.iter().position(|(id, _)| *id == item.id())
322    }
323
324    pub fn activate_item(&mut self, index: usize, cx: &mut ViewContext<Self>) {
325        if index < self.item_views.len() {
326            let prev_active_item_ix = mem::replace(&mut self.active_item_index, index);
327            if prev_active_item_ix != self.active_item_index
328                && prev_active_item_ix < self.item_views.len()
329            {
330                self.item_views[prev_active_item_ix].1.deactivated(cx);
331            }
332            self.update_active_toolbar(cx);
333            self.focus_active_item(cx);
334            self.activate(cx);
335            cx.notify();
336        }
337    }
338
339    pub fn activate_prev_item(&mut self, cx: &mut ViewContext<Self>) {
340        let mut index = self.active_item_index;
341        if index > 0 {
342            index -= 1;
343        } else if self.item_views.len() > 0 {
344            index = self.item_views.len() - 1;
345        }
346        self.activate_item(index, cx);
347    }
348
349    pub fn activate_next_item(&mut self, cx: &mut ViewContext<Self>) {
350        let mut index = self.active_item_index;
351        if index + 1 < self.item_views.len() {
352            index += 1;
353        } else {
354            index = 0;
355        }
356        self.activate_item(index, cx);
357    }
358
359    pub fn close_active_item(&mut self, cx: &mut ViewContext<Self>) {
360        if !self.item_views.is_empty() {
361            self.close_item(self.item_views[self.active_item_index].1.id(), cx)
362        }
363    }
364
365    pub fn close_inactive_items(&mut self, cx: &mut ViewContext<Self>) {
366        if !self.item_views.is_empty() {
367            let active_item_id = self.item_views[self.active_item_index].1.id();
368            self.close_items(cx, |id| id != active_item_id);
369        }
370    }
371
372    pub fn close_item(&mut self, view_id_to_close: usize, cx: &mut ViewContext<Self>) {
373        self.close_items(cx, |view_id| view_id == view_id_to_close);
374    }
375
376    pub fn close_items(
377        &mut self,
378        cx: &mut ViewContext<Self>,
379        should_close: impl Fn(usize) -> bool,
380    ) {
381        let mut item_ix = 0;
382        let mut new_active_item_index = self.active_item_index;
383        self.item_views.retain(|(_, item_view)| {
384            if should_close(item_view.id()) {
385                if item_ix == self.active_item_index {
386                    item_view.deactivated(cx);
387                }
388
389                if item_ix < self.active_item_index {
390                    new_active_item_index -= 1;
391                }
392
393                let mut nav_history = self.nav_history.borrow_mut();
394                if let Some(path) = item_view.project_path(cx) {
395                    nav_history.paths_by_item.insert(item_view.id(), path);
396                } else {
397                    nav_history.paths_by_item.remove(&item_view.id());
398                }
399
400                item_ix += 1;
401                false
402            } else {
403                item_ix += 1;
404                true
405            }
406        });
407
408        if self.item_views.is_empty() {
409            cx.emit(Event::Remove);
410        } else {
411            self.active_item_index = cmp::min(new_active_item_index, self.item_views.len() - 1);
412            self.focus_active_item(cx);
413            self.activate(cx);
414        }
415        self.update_active_toolbar(cx);
416
417        cx.notify();
418    }
419
420    fn focus_active_item(&mut self, cx: &mut ViewContext<Self>) {
421        if let Some(active_item) = self.active_item() {
422            cx.focus(active_item);
423        }
424    }
425
426    pub fn split(&mut self, direction: SplitDirection, cx: &mut ViewContext<Self>) {
427        cx.emit(Event::Split(direction));
428    }
429
430    pub fn show_toolbar<F, V>(&mut self, cx: &mut ViewContext<Self>, build_toolbar: F)
431    where
432        F: FnOnce(&mut ViewContext<V>) -> V,
433        V: Toolbar,
434    {
435        let type_id = TypeId::of::<V>();
436        if self.active_toolbar_type != Some(type_id) {
437            self.dismiss_toolbar(cx);
438
439            let active_item = self.active_item();
440            self.toolbars
441                .entry(type_id)
442                .or_insert_with(|| Box::new(cx.add_view(build_toolbar)));
443
444            self.active_toolbar_type = Some(type_id);
445            self.active_toolbar_visible =
446                self.toolbars[&type_id].active_item_changed(active_item, cx);
447            cx.notify();
448        }
449    }
450
451    pub fn dismiss_toolbar(&mut self, cx: &mut ViewContext<Self>) {
452        if let Some(active_toolbar_type) = self.active_toolbar_type.take() {
453            self.toolbars
454                .get_mut(&active_toolbar_type)
455                .unwrap()
456                .on_dismiss(cx);
457            self.active_toolbar_visible = false;
458            self.focus_active_item(cx);
459            cx.notify();
460        }
461    }
462
463    pub fn toolbar<T: Toolbar>(&self) -> Option<ViewHandle<T>> {
464        self.toolbars
465            .get(&TypeId::of::<T>())
466            .and_then(|toolbar| toolbar.to_any().downcast())
467    }
468
469    pub fn active_toolbar(&self) -> Option<AnyViewHandle> {
470        let type_id = self.active_toolbar_type?;
471        let toolbar = self.toolbars.get(&type_id)?;
472        if self.active_toolbar_visible {
473            Some(toolbar.to_any())
474        } else {
475            None
476        }
477    }
478
479    fn update_active_toolbar(&mut self, cx: &mut ViewContext<Self>) {
480        let active_item = self.item_views.get(self.active_item_index);
481        for (toolbar_type_id, toolbar) in &self.toolbars {
482            let visible = toolbar.active_item_changed(active_item.map(|i| i.1.clone()), cx);
483            if Some(*toolbar_type_id) == self.active_toolbar_type {
484                self.active_toolbar_visible = visible;
485            }
486        }
487    }
488
489    fn render_tabs(&self, cx: &mut RenderContext<Self>) -> ElementBox {
490        let settings = self.settings.borrow();
491        let theme = &settings.theme;
492
493        enum Tabs {}
494        let tabs = MouseEventHandler::new::<Tabs, _, _>(0, cx, |mouse_state, cx| {
495            let mut row = Flex::row();
496            for (ix, (_, item_view)) in self.item_views.iter().enumerate() {
497                let is_active = ix == self.active_item_index;
498
499                row.add_child({
500                    let tab_style = if is_active {
501                        theme.workspace.active_tab.clone()
502                    } else {
503                        theme.workspace.tab.clone()
504                    };
505                    let title = item_view.tab_content(&tab_style, cx);
506
507                    let mut style = if is_active {
508                        theme.workspace.active_tab.clone()
509                    } else {
510                        theme.workspace.tab.clone()
511                    };
512                    if ix == 0 {
513                        style.container.border.left = false;
514                    }
515
516                    EventHandler::new(
517                        Container::new(
518                            Flex::row()
519                                .with_child(
520                                    Align::new({
521                                        let diameter = 7.0;
522                                        let icon_color = if item_view.has_conflict(cx) {
523                                            Some(style.icon_conflict)
524                                        } else if item_view.is_dirty(cx) {
525                                            Some(style.icon_dirty)
526                                        } else {
527                                            None
528                                        };
529
530                                        ConstrainedBox::new(
531                                            Canvas::new(move |bounds, _, cx| {
532                                                if let Some(color) = icon_color {
533                                                    let square = RectF::new(
534                                                        bounds.origin(),
535                                                        vec2f(diameter, diameter),
536                                                    );
537                                                    cx.scene.push_quad(Quad {
538                                                        bounds: square,
539                                                        background: Some(color),
540                                                        border: Default::default(),
541                                                        corner_radius: diameter / 2.,
542                                                    });
543                                                }
544                                            })
545                                            .boxed(),
546                                        )
547                                        .with_width(diameter)
548                                        .with_height(diameter)
549                                        .boxed()
550                                    })
551                                    .boxed(),
552                                )
553                                .with_child(
554                                    Container::new(Align::new(title).boxed())
555                                        .with_style(ContainerStyle {
556                                            margin: Margin {
557                                                left: style.spacing,
558                                                right: style.spacing,
559                                                ..Default::default()
560                                            },
561                                            ..Default::default()
562                                        })
563                                        .boxed(),
564                                )
565                                .with_child(
566                                    Align::new(
567                                        ConstrainedBox::new(if mouse_state.hovered {
568                                            let item_id = item_view.id();
569                                            enum TabCloseButton {}
570                                            let icon = Svg::new("icons/x.svg");
571                                            MouseEventHandler::new::<TabCloseButton, _, _>(
572                                                item_id,
573                                                cx,
574                                                |mouse_state, _| {
575                                                    if mouse_state.hovered {
576                                                        icon.with_color(style.icon_close_active)
577                                                            .boxed()
578                                                    } else {
579                                                        icon.with_color(style.icon_close).boxed()
580                                                    }
581                                                },
582                                            )
583                                            .with_padding(Padding::uniform(4.))
584                                            .with_cursor_style(CursorStyle::PointingHand)
585                                            .on_click(move |cx| {
586                                                cx.dispatch_action(CloseItem(item_id))
587                                            })
588                                            .named("close-tab-icon")
589                                        } else {
590                                            Empty::new().boxed()
591                                        })
592                                        .with_width(style.icon_width)
593                                        .boxed(),
594                                    )
595                                    .boxed(),
596                                )
597                                .boxed(),
598                        )
599                        .with_style(style.container)
600                        .boxed(),
601                    )
602                    .on_mouse_down(move |cx| {
603                        cx.dispatch_action(ActivateItem(ix));
604                        true
605                    })
606                    .boxed()
607                })
608            }
609
610            row.add_child(
611                Empty::new()
612                    .contained()
613                    .with_border(theme.workspace.tab.container.border)
614                    .flexible(0., true)
615                    .named("filler"),
616            );
617
618            row.boxed()
619        });
620
621        ConstrainedBox::new(tabs.boxed())
622            .with_height(theme.workspace.tab.height)
623            .named("tabs")
624    }
625}
626
627impl Entity for Pane {
628    type Event = Event;
629}
630
631impl View for Pane {
632    fn ui_name() -> &'static str {
633        "Pane"
634    }
635
636    fn render(&mut self, cx: &mut RenderContext<Self>) -> ElementBox {
637        if let Some(active_item) = self.active_item() {
638            Flex::column()
639                .with_child(self.render_tabs(cx))
640                .with_children(
641                    self.active_toolbar()
642                        .as_ref()
643                        .map(|view| ChildView::new(view).boxed()),
644                )
645                .with_child(ChildView::new(active_item).flexible(1., true).boxed())
646                .named("pane")
647        } else {
648            Empty::new().named("pane")
649        }
650    }
651
652    fn on_focus(&mut self, cx: &mut ViewContext<Self>) {
653        self.focus_active_item(cx);
654    }
655}
656
657impl<T: Toolbar> ToolbarHandle for ViewHandle<T> {
658    fn active_item_changed(
659        &self,
660        item: Option<Box<dyn ItemViewHandle>>,
661        cx: &mut MutableAppContext,
662    ) -> bool {
663        self.update(cx, |this, cx| this.active_item_changed(item, cx))
664    }
665
666    fn on_dismiss(&self, cx: &mut MutableAppContext) {
667        self.update(cx, |this, cx| this.on_dismiss(cx));
668    }
669
670    fn to_any(&self) -> AnyViewHandle {
671        self.into()
672    }
673}
674
675impl ItemNavHistory {
676    pub fn new<T: ItemView>(history: Rc<RefCell<NavHistory>>, item_view: &ViewHandle<T>) -> Self {
677        Self {
678            history,
679            item_view: Rc::new(item_view.downgrade()),
680        }
681    }
682
683    pub fn history(&self) -> Rc<RefCell<NavHistory>> {
684        self.history.clone()
685    }
686
687    pub fn push<D: 'static + Any>(&self, data: Option<D>) {
688        self.history.borrow_mut().push(data, self.item_view.clone());
689    }
690}
691
692impl NavHistory {
693    pub fn disable(&mut self) {
694        self.mode = NavigationMode::Disabled;
695    }
696
697    pub fn enable(&mut self) {
698        self.mode = NavigationMode::Normal;
699    }
700
701    pub fn pop_backward(&mut self) -> Option<NavigationEntry> {
702        self.backward_stack.pop_back()
703    }
704
705    pub fn pop_forward(&mut self) -> Option<NavigationEntry> {
706        self.forward_stack.pop_back()
707    }
708
709    fn pop(&mut self, mode: NavigationMode) -> Option<NavigationEntry> {
710        match mode {
711            NavigationMode::Normal | NavigationMode::Disabled => None,
712            NavigationMode::GoingBack => self.pop_backward(),
713            NavigationMode::GoingForward => self.pop_forward(),
714        }
715    }
716
717    fn set_mode(&mut self, mode: NavigationMode) {
718        self.mode = mode;
719    }
720
721    pub fn push<D: 'static + Any>(
722        &mut self,
723        data: Option<D>,
724        item_view: Rc<dyn WeakItemViewHandle>,
725    ) {
726        match self.mode {
727            NavigationMode::Disabled => {}
728            NavigationMode::Normal => {
729                if self.backward_stack.len() >= MAX_NAVIGATION_HISTORY_LEN {
730                    self.backward_stack.pop_front();
731                }
732                self.backward_stack.push_back(NavigationEntry {
733                    item_view,
734                    data: data.map(|data| Box::new(data) as Box<dyn Any>),
735                });
736                self.forward_stack.clear();
737            }
738            NavigationMode::GoingBack => {
739                if self.forward_stack.len() >= MAX_NAVIGATION_HISTORY_LEN {
740                    self.forward_stack.pop_front();
741                }
742                self.forward_stack.push_back(NavigationEntry {
743                    item_view,
744                    data: data.map(|data| Box::new(data) as Box<dyn Any>),
745                });
746            }
747            NavigationMode::GoingForward => {
748                if self.backward_stack.len() >= MAX_NAVIGATION_HISTORY_LEN {
749                    self.backward_stack.pop_front();
750                }
751                self.backward_stack.push_back(NavigationEntry {
752                    item_view,
753                    data: data.map(|data| Box::new(data) as Box<dyn Any>),
754                });
755            }
756        }
757    }
758}