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.

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

@@ -2945,6 +2945,7 @@ 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);
 }
 
@@ -2954,6 +2955,7 @@ 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);
 }
 
@@ -2975,6 +2977,7 @@ fn goto_next_diag(cx: &mut Context) {
         Some(diag) => Selection::single(diag.range.start, diag.range.end),
         None => return,
     };
+
     doc.set_selection(view.id, selection);
 }
 
@@ -2999,6 +3002,7 @@ fn goto_prev_diag(cx: &mut Context) {
         Some(diag) => Selection::single(diag.range.end, diag.range.start),
         None => return,
     };
+
     doc.set_selection(view.id, selection);
 }
 
@@ -4295,51 +4299,62 @@ fn rotate_selection_contents_backward(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);
 
         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);
             }
         }
     };
+
     motion(cx.editor);
     cx.editor.last_motion = Some(Motion(Box::new(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) {
-                // allow shrinking the selection only if current selection contains the previous object selection
-                doc.set_selection(view.id, prev_selection);
-                return;
-            } else {
-                // clear existing selection as they can't be shrunk to anyway
-                view.object_selections.clear();
-            }
+        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;
         }
+
         // 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);
         }
     };
+
     motion(cx.editor);
     cx.editor.last_motion = Some(Motion(Box::new(motion)));
 }
@@ -4389,8 +4404,6 @@ fn match_brackets(cx: &mut Context) {
     }
 }
 
-//
-
 fn jump_forward(cx: &mut Context) {
     let count = cx.count();
     let config = cx.editor.config();

helix-view/src/document.rs

@@ -109,6 +109,7 @@ pub struct Document {
     pub(crate) id: DocumentId,
     text: Rope,
     selections: HashMap<ViewId, Selection>,
+    view_data: HashMap<ViewId, ViewData>,
 
     path: Option<PathBuf>,
     encoding: &'static encoding::Encoding,
@@ -159,6 +160,7 @@ impl fmt::Debug for Document {
             .field("id", &self.id)
             .field("text", &self.text)
             .field("selections", &self.selections)
+            .field("view_data", &self.view_data)
             .field("path", &self.path)
             .field("encoding", &self.encoding)
             .field("restore_cursor", &self.restore_cursor)
@@ -379,6 +381,7 @@ impl Document {
             encoding,
             text,
             selections: HashMap::default(),
+            view_data: Default::default(),
             indent_style: DEFAULT_INDENT,
             line_ending: DEFAULT_LINE_ENDING,
             restore_cursor: false,
@@ -773,11 +776,22 @@ impl Document {
         self.language_server = language_server;
     }
 
-    /// 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(..)));
+
+        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
@@ -1165,6 +1179,14 @@ impl Document {
         &self.selections
     }
 
+    pub fn view_data(&mut self, view_id: ViewId) -> &ViewData {
+        self.view_data.entry(view_id).or_default()
+    }
+
+    pub fn view_data_mut(&mut self, view_id: ViewId) -> &mut ViewData {
+        self.view_data.entry(view_id).or_default()
+    }
+
     pub fn relative_path(&self) -> Option<PathBuf> {
         self.path
             .as_deref()
@@ -1304,6 +1326,13 @@ impl Document {
     }
 }
 
+/// Stores data needed for views that are tied to this specific Document.
+#[derive(Debug, Default)]
+pub struct ViewData {
+    /// used to store previous selections of tree-sitter objects
+    pub object_selections: HashMap<&'static str, Vec<Selection>>,
+}
+
 #[derive(Clone, Debug)]
 pub enum FormatterError {
     SpawningFailed {
@@ -1353,6 +1382,7 @@ 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 =
@@ -1390,7 +1420,9 @@ 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

@@ -116,8 +116,6 @@ 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.
@@ -151,7 +149,6 @@ 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(),
         }