Implement selection rotation with `(` and `)`

book/src/keymap.md

@@ -76,6 +76,8 @@
 | `Alt-;`  | Flip selection cursor and anchor                                  |
 | `C`      | Copy selection onto the next line                                 |
 | `Alt-C`  | Copy selection onto the previous line                             |
+| `(`      | Rotate main selection forward                                     |
+| `)`      | Rotate main selection backward                                    |
 | `%`      | Select entire file                                                |
 | `x`      | Select current line, if already selected, extend to next line     |
 | `X`      | Extend selection to line bounds (line-wise selection)             |

helix-term/src/commands.rs

@@ -275,6 +275,8 @@ impl Command {
         completion, "Invoke completion popup",
         hover, "Show docs for item under cursor",
         toggle_comments, "Comment/uncomment selections",
+        rotate_selections_forward, "Rotate selections forward",
+        rotate_selections_backward, "Rotate selections backward",
         expand_selection, "Expand selection to parent syntax node",
         jump_forward, "Jump forward on jumplist",
         jump_backward, "Jump backward on jumplist",
@@ -3747,6 +3749,25 @@ fn toggle_comments(cx: &mut Context) {
     doc.append_changes_to_history(view.id);
 }
 
+fn rotate_selections(cx: &mut Context, direction: Direction) {
+    let count = cx.count();
+    let (view, doc) = current!(cx.editor);
+    let mut selection = doc.selection(view.id).clone();
+    let index = selection.primary_index();
+    let len = selection.len();
+    selection.set_primary_index(match direction {
+        Direction::Forward => (index + count) % len,
+        Direction::Backward => (index + (len.saturating_sub(count) % len)) % len,
+    });
+    doc.set_selection(view.id, selection);
+}
+fn rotate_selections_forward(cx: &mut Context) {
+    rotate_selections(cx, Direction::Forward)
+}
+fn rotate_selections_backward(cx: &mut Context) {
+    rotate_selections(cx, Direction::Backward)
+}
+
 // tree sitter node selection
 
 fn expand_selection(cx: &mut Context) {

helix-term/src/keymap.rs

@@ -451,7 +451,8 @@ impl Default for Keymaps {
             // & align selections
             // _ trim selections
 
-            // C / altC = copy (repeat) selections on prev/next lines
+            "(" => rotate_selections_backward,
+            ")" => rotate_selections_forward,
 
             "esc" => normal_mode,
             "C-b" | "pageup" => page_up,
@@ -508,9 +509,6 @@ impl Default for Keymaps {
             "\"" => select_register,
             "C-z" => suspend,
         });
-        // TODO: decide whether we want normal mode to also be select mode (kakoune-like), or whether
-        // we keep this separate select mode. More keys can fit into normal mode then, but it's weird
-        // because some selection operations can now be done from normal mode, some from select mode.
         let mut select = normal.clone();
         select.merge_nodes(keymap!({ "Select mode"
             "h" | "left" => extend_char_left,