FakeVim: Keep undo/redo integrity while the plugin is disabled

Change-Id: If17252ecfd7adc6bbe518ce97908f1f8fb2772f1
Reviewed-by: hjk <hjk121@nokiamail.com>

src/plugins/fakevim/fakevimhandler.cpp

@@ -1794,6 +1794,7 @@ public:
     QStack<State> m_undo;
     QStack<State> m_redo;
     State m_undoState;
+    int m_lastUndoSteps;
 
     // extra data for '.'
     void replay(const QString &text);
@@ -1957,6 +1958,7 @@ FakeVimHandler::Private::Private(FakeVimHandler *parent, QWidget *widget)
     if (editor()) {
         connect(EDITOR(document()), SIGNAL(contentsChanged()), SLOT(onContentsChanged()));
         connect(EDITOR(document()), SIGNAL(undoCommandAdded()), SLOT(onUndoCommandAdded()));
+        m_lastUndoSteps = document()->availableUndoSteps();
     }
     //new Highlighter(document(), &pythonRules);
     init();
@@ -2375,10 +2377,7 @@ void FakeVimHandler::Private::restoreWidget(int tabSize)
     EDITOR(setTabStopWidth(charWidth * tabSize));
     m_visualMode = NoVisualMode;
     // Force "ordinary" cursor.
-    m_mode = InsertMode;
+    EDITOR(setOverwriteMode(false));
-    m_submode = NoSubMode;
-    m_subsubmode = NoSubSubMode;
-    updateCursorShape();
     updateSelection();
     updateHighlights();
 }
@@ -7090,17 +7089,37 @@ void FakeVimHandler::Private::onContentsChanged()
 {
     if (!document()->isUndoAvailable())
         m_undo.clear();
-    else if (m_editBlockLevel == 0 && !m_undo.isEmpty() && !isInsertMode())
+
-        m_undo.push(State()); // Save undo state for external change.
+    const int undoSteps = document()->availableUndoSteps();
+
+    if (m_editBlockLevel == 0) {
+        // Break undo/redo stacks on external undo/redo.
+        if (m_lastUndoSteps > undoSteps && !m_undo.isEmpty()) {
+            if ((--m_undo.top().revisions) <= 0)
+                m_undo.pop();
+            m_redo.push(State());
+        } else if (m_lastUndoSteps < undoSteps && !m_redo.isEmpty()) {
+            if ((--m_redo.top().revisions) <= 0)
+                m_redo.pop();
+            m_undo.push(State());
+        }
+    }
+
+    m_lastUndoSteps = undoSteps;
 }
 
 void FakeVimHandler::Private::onUndoCommandAdded()
 {
     m_redo.clear();
-    if (m_editBlockLevel == 0 && !m_undo.isEmpty() && isInsertMode())
+    // Remember chage so it can be correctly undone/redone with undo/redo commands.
-        ++m_undo.top().revisions;
+    if (m_editBlockLevel == 0 && !m_undo.isEmpty()) {
+        if (isInsertMode())
+            ++m_undo.top().revisions; // External change in insert mode (auto-completion etc.)
         else
-        ++m_undoState.revisions;
+            m_undo.push(State()); // External change while FakeVim disabled.
+    } else if (m_editBlockLevel > 0) {
+        ++m_undoState.revisions; // Document revision increased in our edit block.
+    }
 }
 
 char FakeVimHandler::Private::currentModeCode() const
@@ -7164,11 +7183,11 @@ void FakeVimHandler::Private::undoRedo(bool undo)
         setMark(QLatin1Char('`'), lastPos);
         setCursorPosition(m_lastChangePosition);
         setAnchor();
-        stack2.push(state);
     } else {
         updateFirstVisibleLine();
         m_cursor = EDITOR(textCursor());
     }
+    stack2.push(state);
 
     setTargetColumn();
     if (atEndOfLine())