Generalize View::object_selections into map

This allows using multiple distinct state histories. By default, all
history is also cleared any time a view's selection is set, unless
explicitly told to save the state. This way, we can have control over
when selection history is saved. They are also cleared on any text
edit, since an edit could invalidate the previous selection, potentially
causing a panic.

Additionally, the object selections have been moved into `Document`
so that it is easier to manipulate them when changes to the document
happen. They have been put into a wrapper struct named `ViewData`, where
the intention is that any further fields that we want to add in the
future that must be associated with a view, but are more convenient to
store in a document, can be added here, instead of further polluting the
core `Document` type.

helix-term/src/commands.rs

@@ -3662,6 +3662,7 @@ fn goto_first_diag(cx: &mut Context) {
         Some(diag) => Selection::single(diag.range.start, diag.range.end),
         None => return,
     };
+
     doc.set_selection(view.id, selection);
     view.diagnostics_handler
         .immediately_show_diagnostic(doc, view.id);
@@ -3673,6 +3674,7 @@ fn goto_last_diag(cx: &mut Context) {
         Some(diag) => Selection::single(diag.range.start, diag.range.end),
         None => return,
     };
+
     doc.set_selection(view.id, selection);
     view.diagnostics_handler
         .immediately_show_diagnostic(doc, view.id);
@@ -3731,6 +3733,7 @@ fn goto_prev_diag(cx: &mut Context) {
         view.diagnostics_handler
             .immediately_show_diagnostic(doc, view.id);
     };
+
     cx.editor.apply_motion(motion)
 }
 
@@ -5029,6 +5032,8 @@ fn reverse_selection_contents(cx: &mut Context) {
 
 // tree sitter node selection
 
+const EXPAND_KEY: &str = "expand";
+
 fn expand_selection(cx: &mut Context) {
     let motion = |editor: &mut Editor| {
         let (view, doc) = current!(editor);
@@ -5036,42 +5041,52 @@ fn expand_selection(cx: &mut Context) {
         if let Some(syntax) = doc.syntax() {
             let text = doc.text().slice(..);
 
-            let current_selection = doc.selection(view.id);
+            let current_selection = doc.selection(view.id).clone();
             let selection = object::expand_selection(syntax, text, current_selection.clone());
 
             // check if selection is different from the last one
-            if *current_selection != selection {
-                // save current selection so it can be restored using shrink_selection
-                view.object_selections.push(current_selection.clone());
+            if current_selection != selection {
+                let prev_selections = doc
+                    .view_data_mut(view.id)
+                    .object_selections
+                    .entry(EXPAND_KEY)
+                    .or_default();
 
-                doc.set_selection(view.id, selection);
+                // save current selection so it can be restored using shrink_selection
+                prev_selections.push(current_selection);
+                doc.set_selection_clear(view.id, selection, false);
             }
         }
     };
+
     cx.editor.apply_motion(motion);
 }
 
 fn shrink_selection(cx: &mut Context) {
     let motion = |editor: &mut Editor| {
         let (view, doc) = current!(editor);
-        let current_selection = doc.selection(view.id);
+        let current_selection = doc.selection(view.id).clone();
+        let prev_expansions = doc
+            .view_data_mut(view.id)
+            .object_selections
+            .entry(EXPAND_KEY)
+            .or_default();
+
         // try to restore previous selection
-        if let Some(prev_selection) = view.object_selections.pop() {
-            if current_selection.contains(&prev_selection) {
-                doc.set_selection(view.id, prev_selection);
+        if let Some(prev_selection) = prev_expansions.pop() {
+            // allow shrinking the selection only if current selection contains the previous object selection
+            doc.set_selection_clear(view.id, prev_selection, false);
             return;
-            } else {
-                // clear existing selection as they can't be shrunk to anyway
-                view.object_selections.clear();
-            }
         }
+
         // if not previous selection, shrink to first child
         if let Some(syntax) = doc.syntax() {
             let text = doc.text().slice(..);
-            let selection = object::shrink_selection(syntax, text, current_selection.clone());
-            doc.set_selection(view.id, selection);
+            let selection = object::shrink_selection(syntax, text, current_selection);
+            doc.set_selection_clear(view.id, selection, false);
         }
     };
+
     cx.editor.apply_motion(motion);
 }
 
@@ -5190,8 +5205,6 @@ fn match_brackets(cx: &mut Context) {
     doc.set_selection(view.id, selection);
 }
 
-//
-
 fn jump_forward(cx: &mut Context) {
     let count = cx.count();
     let config = cx.editor.config();

helix-view/src/document.rs

@@ -1213,15 +1213,27 @@ impl Document {
         Ok(())
     }
 
-    /// Select text within the [`Document`].
-    pub fn set_selection(&mut self, view_id: ViewId, selection: Selection) {
+    /// Select text within the [`Document`], optionally clearing the previous selection state.
+    pub fn set_selection_clear(&mut self, view_id: ViewId, selection: Selection, clear_prev: bool) {
         // TODO: use a transaction?
         self.selections
             .insert(view_id, selection.ensure_invariants(self.text().slice(..)));
+
         helix_event::dispatch(SelectionDidChange {
             doc: self,
             view: view_id,
-        })
+        });
+
+        if clear_prev {
+            self.view_data
+                .entry(view_id)
+                .and_modify(|view_data| view_data.object_selections.clear());
+        }
+    }
+
+    /// Select text within the [`Document`].
+    pub fn set_selection(&mut self, view_id: ViewId, selection: Selection) {
+        self.set_selection_clear(view_id, selection, true);
     }
 
     /// Find the origin selection of the text in a document, i.e. where
@@ -1408,6 +1420,12 @@ impl Document {
             apply_inlay_hint_changes(padding_after_inlay_hints);
         }
 
+        // clear out all associated view object selections, as they are no
+        // longer valid
+        self.view_data
+            .values_mut()
+            .for_each(|view_data| view_data.object_selections.clear());
+
         helix_event::dispatch(DocumentDidChange {
             doc: self,
             view: view_id,
@@ -1834,13 +1852,13 @@ impl Document {
         &self.selections
     }
 
-    fn view_data(&self, view_id: ViewId) -> &ViewData {
+    pub fn view_data(&self, view_id: ViewId) -> &ViewData {
         self.view_data
             .get(&view_id)
             .expect("This should only be called after ensure_view_init")
     }
 
-    fn view_data_mut(&mut self, view_id: ViewId) -> &mut ViewData {
+    pub fn view_data_mut(&mut self, view_id: ViewId) -> &mut ViewData {
         self.view_data.entry(view_id).or_default()
     }
 
@@ -2134,9 +2152,13 @@ impl Document {
     }
 }
 
+/// Stores data needed for views that are tied to this specific Document.
 #[derive(Debug, Default)]
 pub struct ViewData {
     view_position: ViewPosition,
+
+    /// used to store previous selections of tree-sitter objects
+    pub object_selections: HashMap<&'static str, Vec<Selection>>,
 }
 
 #[derive(Clone, Debug)]
@@ -2188,6 +2210,7 @@ mod test {
             Arc::new(ArcSwap::new(Arc::new(Config::default()))),
         );
         let view = ViewId::default();
+        doc.ensure_view_init(view);
         doc.set_selection(view, Selection::single(0, 0));
 
         let transaction =
@@ -2225,7 +2248,9 @@ mod test {
             None,
             Arc::new(ArcSwap::new(Arc::new(Config::default()))),
         );
+
         let view = ViewId::default();
+        doc.ensure_view_init(view);
         doc.set_selection(view, Selection::single(5, 5));
 
         // insert

helix-view/src/view.rs

@@ -138,8 +138,6 @@ pub struct View {
     // uses two docs because we want to be able to swap between the
     // two last modified docs which we need to manually keep track of
     pub last_modified_docs: [Option<DocumentId>; 2],
-    /// used to store previous selections of tree-sitter objects
-    pub object_selections: Vec<Selection>,
     /// all gutter-related configuration settings, used primarily for gutter rendering
     pub gutters: GutterConfig,
     /// A mapping between documents and the last history revision the view was updated at.
@@ -176,7 +174,6 @@ impl View {
             jumps: JumpList::new((doc, Selection::point(0))), // TODO: use actual sel
             docs_access_history: Vec::new(),
             last_modified_docs: [None, None],
-            object_selections: Vec::new(),
             gutters,
             doc_revisions: HashMap::new(),
             diagnostics_handler: DiagnosticsHandler::new(),