For undo/redo, isolate changes made externally from our own changes

Make change X, git revert, make change Y, undo.
Before this commit, undo would take us to before the revert. Now, correctly takes us to before change Y.

Author: J-Fields

src/history/historyTracker.ts

@@ -681,9 +681,9 @@ export class HistoryTracker {
    *
    * Determines what changed by diffing the document against what it used to look like.
    */
-  public addChange(force: boolean = false): void {
+  public addChange(force: boolean = false): boolean {
     if (this.getDocumentVersion() === this.previousDocumentState.versionNumber) {
-      return;
+      return false;
     }
 
     if (this.nextStepCursorsAtStart === undefined) {
@@ -698,12 +698,12 @@ export class HistoryTracker {
       // We can ignore changes while we're in insert/replace mode, since we can't interact with them (via undo, etc.) until we're back to normal mode
       // This allows us to avoid a little bit of work per keystroke, but more importantly, it means we'll get bigger contiguous edit chunks to merge.
       // This is particularly impactful when there are multiple cursors, which are otherwise difficult to optimize.
-      return;
+      return false;
     }
 
     const newText = this.getDocumentText();
     if (newText === this.previousDocumentState.text) {
-      return;
+      return false;
     }
 
     // TODO: This is actually pretty stupid! Since we already have the cursorPosition,
@@ -741,6 +741,8 @@ export class HistoryTracker {
       text: newText,
       versionNumber: this.getDocumentVersion(),
     };
+
+    return true;
   }
 
   /**

src/mode/modeHandler.ts

@@ -613,7 +613,10 @@ export class ModeHandler implements vscode.Disposable, IModeHandler {
     }
 
     // Catch any text change not triggered by us (example: tab completion).
-    this.vimState.historyTracker.addChange();
+    const changeAdded = this.vimState.historyTracker.addChange();
+    if (changeAdded) {
+      this.vimState.historyTracker.finishCurrentStep();
+    }
 
     const recordedState = this.vimState.recordedState;
     recordedState.actionKeys.push(key);

test/mode/normalModeTests/undo.test.ts

@@ -148,6 +148,9 @@ suite('Undo', () => {
       keysPressed: 'R' + '123' + '<C-g>u' + '456' + '<Esc>' + 'u',
       end: ['123|DEF'],
     });
+
+    // TODO: Make change X, git revert, make change Y, undo
+    // TODO: Test interaction with VS Code's native undo
   });
 
   suite('U', () => {