1 files changed, 71 insertions, 0 deletions
diff --git a/src/corelib/json/qjson_p.h b/src/corelib/json/qjson_p.h
index 7d0162938d..92330175ba 100644
--- a/src/corelib/json/qjson_p.h
+++ b/src/corelib/json/qjson_p.h
@@ -61,6 +61,8 @@
 #include <qstring.h>
 #include <qendian.h>
 #include <qnumeric.h>
+#include <QtCore/qhash.h>
+#include <QtCore/qmutex.h>
 
 #include <limits.h>
 #include <limits>
@@ -776,6 +778,75 @@ private:
     Q_DISABLE_COPY(Data)
 };
 
+struct ObjectUndefinedKeys
+{
+    static void insertKey(const QJsonObject *object, int index, const QString &key)
+    {
+        QMutexLocker lock(&mutex);
+        keys()[object][index] = key;
+    }
+    static QString takeKey(const QJsonObject *object, int index)
+    {
+        QMutexLocker lock(&mutex);
+        return keys()[object].take(index);
+    }
+    static void removeKeys(const QJsonObject *object)
+    {
+        QMutexLocker lock(&mutex);
+        keys().remove(object);
+    }
+private:
+    typedef QHash<const QJsonObject*, QHash<int, QString> > KeysHash;
+    static KeysHash &keys()
+    {
+        static KeysHash keys;
+        return keys;
+    }
+   static QBasicMutex mutex;
+};
+
+} // namespace QJsonPrivate
+
+struct QJsonValueRef::UnionHelper
+{
+    static inline QJsonObject *untaggedPointer(QJsonObject *object)
+    {
+        const quintptr Mask = ~quintptr(0) << 2;
+        return reinterpret_cast<QJsonObject*>(quintptr(object) & Mask);
+    }
+    static inline QJsonObject *taggedPointer(QJsonObject *object)
+    {
+        const quintptr Mask = 1;
+        return reinterpret_cast<QJsonObject*>(quintptr(object) | Mask);
+    }
+
+    static void setValueAt(QJsonValueRef *ref, QJsonValue value)
+    {
+        using namespace QJsonPrivate;
+        QJsonObject *object = untaggedPointer(ref->o);
+        if (ref->o != object)
+            object->insert(ObjectUndefinedKeys::takeKey(object, ref->index), value);
+        else
+            object->setValueAt(ref->index, value);
+    }
+
+    static QJsonValue valueAt(const QJsonValueRef *ref)
+    {
+        QJsonObject *object = untaggedPointer(ref->o);
+        if (ref->o != object)
+            return QJsonValue::Undefined;
+        return ref->o->valueAt(ref->index);
+    }
+};
+
+/*!
+    \internal
+    Constructor that creates reference to an undefined value in \a object.
+*/
+inline QJsonValueRef::QJsonValueRef(QJsonObject *object, const QString &key)
+    : o(UnionHelper::taggedPointer(object)), is_object(true), index(qHash(key))
+{
+    QJsonPrivate::ObjectUndefinedKeys::insertKey(object, index, key);
 }
 
 QT_END_NAMESPACE