Start laying the foundation for a per-pane navigation system

crates/workspace/src/pane.rs

@@ -1,5 +1,6 @@
 use super::{ItemViewHandle, SplitDirection};
-use crate::{ItemHandle, Settings, Workspace};
+use crate::{ItemHandle, ItemView, Settings, WeakItemViewHandle, Workspace};
+use collections::HashMap;
 use gpui::{
     action,
     elements::*,
@@ -9,7 +10,8 @@ use gpui::{
     Entity, MutableAppContext, Quad, RenderContext, View, ViewContext,
 };
 use postage::watch;
-use std::cmp;
+use project::ProjectPath;
+use std::{any::Any, cell::RefCell, cmp, rc::Rc};
 
 action!(Split, SplitDirection);
 action!(ActivateItem, usize);
@@ -17,6 +19,8 @@ action!(ActivatePrevItem);
 action!(ActivateNextItem);
 action!(CloseActiveItem);
 action!(CloseItem, usize);
+action!(GoBack);
+action!(GoForward);
 
 pub fn init(cx: &mut MutableAppContext) {
     cx.add_action(|pane: &mut Pane, action: &ActivateItem, cx| {
@@ -37,6 +41,8 @@ pub fn init(cx: &mut MutableAppContext) {
     cx.add_action(|pane: &mut Pane, action: &Split, cx| {
         pane.split(action.0, cx);
     });
+    cx.add_action(Pane::go_back);
+    cx.add_action(Pane::go_forward);
 
     cx.add_bindings(vec![
         Binding::new("shift-cmd-{", ActivatePrevItem, Some("Pane")),
@@ -46,6 +52,8 @@ pub fn init(cx: &mut MutableAppContext) {
         Binding::new("cmd-k down", Split(SplitDirection::Down), Some("Pane")),
         Binding::new("cmd-k left", Split(SplitDirection::Left), Some("Pane")),
         Binding::new("cmd-k right", Split(SplitDirection::Right), Some("Pane")),
+        Binding::new("ctrl-", GoBack, Some("Pane")),
+        Binding::new("ctrl-shift-_", GoForward, Some("Pane")),
     ]);
 }
 
@@ -61,6 +69,22 @@ pub struct Pane {
     item_views: Vec<(usize, Box<dyn ItemViewHandle>)>,
     active_item: usize,
     settings: watch::Receiver<Settings>,
+    navigation: Rc<Navigation>,
+}
+
+#[derive(Default)]
+pub struct Navigation(RefCell<NavigationHistory>);
+
+#[derive(Default)]
+struct NavigationHistory {
+    backward_stack: Vec<NavigationEntry>,
+    forward_stack: Vec<NavigationEntry>,
+    paths_by_item: HashMap<usize, ProjectPath>,
+}
+
+struct NavigationEntry {
+    item_view: Box<dyn WeakItemViewHandle>,
+    data: Option<Box<dyn Any>>,
 }
 
 impl Pane {
@@ -69,6 +93,7 @@ impl Pane {
             item_views: Vec::new(),
             active_item: 0,
             settings,
+            navigation: Default::default(),
         }
     }
 
@@ -76,6 +101,16 @@ impl Pane {
         cx.emit(Event::Activate);
     }
 
+    pub fn go_back(&mut self, _: &GoBack, cx: &mut ViewContext<Self>) {
+        let mut navigation = self.navigation.0.borrow_mut();
+        if let Some(entry) = navigation.go_back() {}
+    }
+
+    pub fn go_forward(&mut self, _: &GoForward, cx: &mut ViewContext<Self>) {
+        let mut navigation = self.navigation.0.borrow_mut();
+        if let Some(entry) = navigation.go_forward() {}
+    }
+
     pub fn open_item<T>(
         &mut self,
         item_handle: T,
@@ -93,14 +128,15 @@ impl Pane {
             }
         }
 
-        let item_view = item_handle.add_view(cx.window_id(), workspace, cx);
+        let item_view =
+            item_handle.add_view(cx.window_id(), workspace, self.navigation.clone(), cx);
         self.add_item_view(item_view.boxed_clone(), cx);
         item_view
     }
 
     pub fn add_item_view(
         &mut self,
-        item_view: Box<dyn ItemViewHandle>,
+        mut item_view: Box<dyn ItemViewHandle>,
         cx: &mut ViewContext<Self>,
     ) {
         item_view.added_to_pane(cx);
@@ -142,6 +178,7 @@ impl Pane {
         if index < self.item_views.len() {
             self.active_item = index;
             self.focus_active_item(cx);
+            self.item_views[index].1.activated(cx);
             cx.notify();
         }
     }
@@ -172,8 +209,21 @@ impl Pane {
         }
     }
 
-    pub fn close_item(&mut self, item_id: usize, cx: &mut ViewContext<Self>) {
-        self.item_views.retain(|(_, item)| item.id() != item_id);
+    pub fn close_item(&mut self, item_view_id: usize, cx: &mut ViewContext<Self>) {
+        self.item_views.retain(|(item_id, item)| {
+            if item.id() == item_view_id {
+                let mut navigation = self.navigation.0.borrow_mut();
+                if let Some(path) = item.project_path(cx) {
+                    navigation.paths_by_item.insert(*item_id, path);
+                } else {
+                    navigation.paths_by_item.remove(item_id);
+                }
+
+                false
+            } else {
+                true
+            }
+        });
         self.active_item = cmp::min(self.active_item, self.item_views.len().saturating_sub(1));
         if self.item_views.is_empty() {
             cx.emit(Event::Remove);
@@ -369,3 +419,33 @@ impl View for Pane {
         self.focus_active_item(cx);
     }
 }
+
+impl Navigation {
+    pub fn push<D: 'static + Any, T: ItemView>(&self, data: Option<D>, cx: &mut ViewContext<T>) {
+        let mut state = self.0.borrow_mut();
+        state.backward_stack.push(NavigationEntry {
+            item_view: Box::new(cx.weak_handle()),
+            data: data.map(|data| Box::new(data) as Box<dyn Any>),
+        });
+    }
+}
+
+impl NavigationHistory {
+    fn go_back(&mut self) -> Option<&NavigationEntry> {
+        if let Some(backward) = self.backward_stack.pop() {
+            self.forward_stack.push(backward);
+            self.forward_stack.last()
+        } else {
+            None
+        }
+    }
+
+    fn go_forward(&mut self) -> Option<&NavigationEntry> {
+        if let Some(forward) = self.forward_stack.pop() {
+            self.backward_stack.push(forward);
+            self.backward_stack.last()
+        } else {
+            None
+        }
+    }
+}