feat(command): expand_selection_around

Introduces a new command `expand_selection_around` that expands the
selection to the parent node, like `expand_selection`, except it splits
on the selection you start with and continues expansion around this
initial selection.

helix-term/src/commands.rs

@@ -381,6 +381,7 @@ impl MappableCommand {
         rotate_selection_contents_backward, "Rotate selections contents backward",
         expand_selection, "Expand selection to parent syntax node",
         shrink_selection, "Shrink selection to previously expanded syntax node",
+        expand_selection_around, "Expand selection to parent syntax node, but exclude the selection you started with",
         select_next_sibling, "Select next sibling in syntax tree",
         select_prev_sibling, "Select previous sibling in syntax tree",
         jump_forward, "Jump forward on jumplist",
@@ -4300,6 +4301,8 @@ fn rotate_selection_contents_backward(cx: &mut Context) {
 // tree sitter node selection
 
 const EXPAND_KEY: &str = "expand";
+const EXPAND_AROUND_BASE_KEY: &str = "expand_around_base";
+const PARENTS_KEY: &str = "parents";
 
 fn expand_selection(cx: &mut Context) {
     let motion = |editor: &mut Editor| {
@@ -4335,6 +4338,27 @@ fn shrink_selection(cx: &mut Context) {
         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, prev_selection, false);
+
+            // Do a corresponding pop of the parents from `expand_selection_around`
+            view.object_selections
+                .entry(PARENTS_KEY)
+                .and_modify(|parents| {
+                    parents.pop();
+                });
+
+            // need to do this again because borrowing
+            let prev_expansions = view.object_selections.entry(EXPAND_KEY).or_default();
+
+            // if we've emptied out the previous expansions, then clear out the
+            // base history as well so it doesn't get used again erroneously
+            if prev_expansions.is_empty() {
+                view.object_selections
+                    .entry(EXPAND_AROUND_BASE_KEY)
+                    .and_modify(|base| {
+                        base.clear();
+                    });
+            }
+
             return;
         }
 
@@ -4350,6 +4374,68 @@ fn shrink_selection(cx: &mut Context) {
     cx.editor.last_motion = Some(Motion(Box::new(motion)));
 }
 
+fn expand_selection_around(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);
+
+            // [NOTE] we do this pop and push dance because if we don't take
+            //        ownership of the objects, then we require multiple
+            //        mutable references to the view's object selections
+            let mut parents_selection =
+                view.object_selections.entry(PARENTS_KEY).or_default().pop();
+            let mut base_selection = view
+                .object_selections
+                .entry(EXPAND_AROUND_BASE_KEY)
+                .or_default()
+                .pop();
+
+            if parents_selection.is_none() || base_selection.is_none() {
+                parents_selection = Some(current_selection.clone());
+                base_selection = Some(current_selection.clone());
+            }
+
+            let outside_selection =
+                object::expand_selection(syntax, text, parents_selection.clone().unwrap());
+
+            let target_selection = match outside_selection
+                .clone()
+                .without(&base_selection.clone().unwrap())
+            {
+                Some(sel) => sel,
+                None => outside_selection.clone(),
+            };
+
+            // check if selection is different from the last one
+            if target_selection != *current_selection {
+                // save current selection so it can be restored using shrink_selection
+                view.object_selections
+                    .entry(EXPAND_KEY)
+                    .or_default()
+                    .push(current_selection.clone());
+
+                doc.set_selection_clear(view, target_selection, false);
+            }
+
+            let parents = view.object_selections.entry(PARENTS_KEY).or_default();
+
+            parents.push(parents_selection.unwrap());
+            parents.push(outside_selection);
+
+            view.object_selections
+                .entry(EXPAND_AROUND_BASE_KEY)
+                .or_default()
+                .push(base_selection.unwrap());
+        }
+    };
+
+    motion(cx.editor);
+    cx.editor.last_motion = Some(Motion(Box::new(motion)));
+}
+
 fn select_sibling_impl<F>(cx: &mut Context, sibling_fn: &'static F)
 where
     F: Fn(Node) -> Option<Node>,

helix-term/src/keymap/default.rs

@@ -84,6 +84,7 @@ pub fn default() -> HashMap<Mode, Keymap> {
         ";" => collapse_selection,
         "A-;" => flip_selections,
         "A-o" | "A-up" => expand_selection,
+        "A-O" => expand_selection_around,
         "A-i" | "A-down" => shrink_selection,
         "A-p" | "A-left" => select_prev_sibling,
         "A-n" | "A-right" => select_next_sibling,

helix-term/tests/test/commands/movement.rs

@@ -129,3 +129,68 @@ async fn expand_shrink_selection() -> anyhow::Result<()> {
 
     Ok(())
 }
+
+#[tokio::test(flavor = "multi_thread")]
+async fn expand_selection_around() -> anyhow::Result<()> {
+    let tests = vec![
+        // single cursor stays single cursor, first goes to end of current
+        // node, then parent
+        (
+            helpers::platform_line(indoc! {r##"
+                Some(#[thing|]#)
+            "##}),
+            "<A-O><A-O>",
+            helpers::platform_line(indoc! {r##"
+                #[Some(|]#thing#()|)#
+            "##}),
+        ),
+        // shrinking restores previous selection
+        (
+            helpers::platform_line(indoc! {r##"
+                Some(#[thing|]#)
+            "##}),
+            "<A-O><A-O><A-i><A-i>",
+            helpers::platform_line(indoc! {r##"
+                Some(#[thing|]#)
+            "##}),
+        ),
+        // multi range collision merges expand as normal, except with the
+        // original selection removed from the result
+        (
+            helpers::platform_line(indoc! {r##"
+                (
+                    Some(#[thing|]#),
+                    Some(#(other_thing|)#),
+                )
+            "##}),
+            "<A-O><A-O><A-O>",
+            helpers::platform_line(indoc! {r##"
+                #[(
+                    Some(|]#thing#(),
+                    Some(|)#other_thing#(),
+                )|)#
+            "##}),
+        ),
+        (
+            helpers::platform_line(indoc! {r##"
+                (
+                    Some(#[thing|]#),
+                    Some(#(other_thing|)#),
+                )
+            "##}),
+            "<A-O><A-O><A-O><A-i><A-i><A-i>",
+            helpers::platform_line(indoc! {r##"
+                (
+                    Some(#[thing|]#),
+                    Some(#(other_thing|)#),
+                )
+            "##}),
+        ),
+    ];
+
+    for test in tests {
+        test_with_config(AppBuilder::new().with_file("foo.rs", None), test).await?;
+    }
+
+    Ok(())
+}