QmlDesigner: Add rollback function to the RewriterTransaction class

Change-Id: I04874043eb04bd3f2cbf330186bb2105ed7ac82b
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>

src/plugins/qmldesigner/designercore/rewritertransaction.cpp

@@ -29,6 +29,8 @@
 
 #include "rewritertransaction.h"
 #include <abstractview.h>
+#include <designdocument.h>
+#include <qmldesignerplugin.h>
 
 namespace QmlDesigner {
 
@@ -61,6 +63,16 @@ void RewriterTransaction::commit()
     }
 }
 
+void RewriterTransaction::rollback()
+{
+    // TODO: should be implemented with a function in the rewriter
+    if (m_valid) {
+        m_valid = false;
+        view()->emitRewriterEndTransaction();
+        QmlDesignerPlugin::instance()->currentDesignDocument()->undo();
+    }
+}
+
 AbstractView *RewriterTransaction::view()
 {
     return m_view.data();

src/plugins/qmldesigner/designercore/rewritertransaction.h

@@ -45,6 +45,7 @@ public:
     RewriterTransaction(AbstractView *view);
     ~RewriterTransaction();
     void commit();
+    void rollback();
     RewriterTransaction(const RewriterTransaction &other);
     RewriterTransaction& operator=(const RewriterTransaction &other);