Re-activate the most recently-activated project search on cmd-shift-F

This commits adds the beginnings of an application state facility as a non-static place to store the most recently-activated search for each project.

I also store workspace items by descending order of their entity id so that we always fetch the newest item of a given type when calling `Workspace::item_of_type`.

crates/workspace/src/workspace.rs

@@ -9,7 +9,7 @@ mod status_bar;
 use anyhow::{anyhow, Result};
 use client::{Authenticate, ChannelList, Client, User, UserStore};
 use clock::ReplicaId;
-use collections::HashSet;
+use collections::BTreeMap;
 use gpui::{
     action,
     color::Color,
@@ -36,6 +36,7 @@ pub use status_bar::StatusItemView;
 use std::{
     any::{Any, TypeId},
     cell::RefCell,
+    cmp::Reverse,
     future::Future,
     hash::{Hash, Hasher},
     path::{Path, PathBuf},
@@ -569,7 +570,7 @@ pub struct Workspace {
     status_bar: ViewHandle<StatusBar>,
     project: ModelHandle<Project>,
     path_openers: Arc<[Box<dyn PathOpener>]>,
-    items: HashSet<Box<dyn WeakItemHandle>>,
+    items: BTreeMap<Reverse<usize>, Box<dyn WeakItemHandle>>,
     _observe_current_user: Task<()>,
 }
 
@@ -815,14 +816,14 @@ impl Workspace {
 
     fn item_for_path(&self, path: &ProjectPath, cx: &AppContext) -> Option<Box<dyn ItemHandle>> {
         self.items
-            .iter()
+            .values()
             .filter_map(|i| i.upgrade(cx))
             .find(|i| i.project_path(cx).as_ref() == Some(path))
     }
 
     pub fn item_of_type<T: Item>(&self, cx: &AppContext) -> Option<ModelHandle<T>> {
         self.items
-            .iter()
+            .values()
             .find_map(|i| i.upgrade(cx).and_then(|i| i.to_any().downcast()))
     }
 
@@ -831,7 +832,7 @@ impl Workspace {
         cx: &'a AppContext,
     ) -> impl 'a + Iterator<Item = ModelHandle<T>> {
         self.items
-            .iter()
+            .values()
             .filter_map(|i| i.upgrade(cx).and_then(|i| i.to_any().downcast()))
     }
 
@@ -974,7 +975,8 @@ impl Workspace {
     where
         T: 'static + ItemHandle,
     {
-        self.items.insert(item_handle.downgrade());
+        self.items
+            .insert(Reverse(item_handle.id()), item_handle.downgrade());
         pane.update(cx, |pane, cx| pane.open_item(item_handle, self, cx))
     }
 
@@ -1068,7 +1070,8 @@ impl Workspace {
         if let Some(item) = pane.read(cx).active_item() {
             let nav_history = new_pane.read(cx).nav_history().clone();
             if let Some(clone) = item.clone_on_split(nav_history, cx.as_mut()) {
-                self.items.insert(clone.item(cx).downgrade());
+                let item = clone.item(cx).downgrade();
+                self.items.insert(Reverse(item.id()), item);
                 new_pane.update(cx, |new_pane, cx| new_pane.add_item_view(clone, cx));
             }
         }