Add undo checkpoint command (#2115)

* added undo checkpoint command

* changed add_undo_checkpoint to commit_undo_checkpoint

* mapped commit_undo_checkpoint to Alt-u

* Update default.rs

Co-authored-by: Blaž Hrastnik <blaz@mxxn.io>

helix-term/src/commands.rs

@@ -318,6 +318,7 @@ impl MappableCommand {
         redo, "Redo change",
         earlier, "Move backward in history",
         later, "Move forward in history",
+        commit_undo_checkpoint, "Commit changes to a new checkpoint",
         yank, "Yank selection",
         yank_joined_to_clipboard, "Join and yank selections to clipboard",
         yank_main_selection_to_clipboard, "Yank main selection to clipboard",
@@ -3001,6 +3002,11 @@ fn later(cx: &mut Context) {
     }
 }
 
+fn commit_undo_checkpoint(cx: &mut Context) {
+    let (view, doc) = current!(cx.editor);
+    doc.append_changes_to_history(view.id);
+}
+
 // Yank / Paste
 
 fn yank(cx: &mut Context) {

helix-term/src/keymap/default.rs

@@ -326,6 +326,7 @@ pub fn default() -> HashMap<Mode, Keymap> {
         "C-w" => delete_word_backward,
         "A-backspace" => delete_word_backward,
         "A-d" => delete_word_forward,
+        "C-s" => commit_undo_checkpoint,
 
         "left" => move_char_left,
         "C-b" => move_char_left,