implement ability to dynamically change class of script objects

With an object created by QScriptEngine::newObject(), it should
be possible to call QScriptValue::setClass() to dynamically
change the behavior of that object. Similarly, it should be
possible to promote plain script objects to QObject (QVariant)
wrappers by calling the overload of QScriptEngine::newQObject()
(newVariant()) that takes a script object as the first argument.
This commit implements this capability.

The premise is the (internal) QScriptObject class, which inherits
JSC::JSObject. It reimplements all the methods for getting/setting
properties etc. Then there's a level of indirection to facilitate
dynamic change of the class: Each QScriptObject can have a
delegate associated with it that will handle operations on the
object. By default there is no delegate, so the object behaves as
a normal JS object, as you expect. However, once a delegate is set
(e.g., when QScriptValue::setScriptClass() is called),
QScriptObject will give the delegate the chance to handle the
object operation.

In addition to a delegate implementation for QScriptClass-based
objects, there are also delegates for QObject and QVariant
wrappers. These replace the QObjectWrapperObject and
QVariantWrapperObject classes.

1 files changed, 9 insertions, 16 deletions

diff --git a/src/script/bridge/qscriptvariant_p.h b/src/script/bridge/qscriptvariant_p.h
index 6e74a6b..ae6564c 100644
--- a/src/script/bridge/qscriptvariant_p.h
+++ b/src/script/bridge/qscriptvariant_p.h
@@ -27,36 +27,29 @@
 
 #ifndef QT_NO_SCRIPT
 
-#include "JSObject.h"
+#include "qscriptobject_p.h"
 
 QT_BEGIN_NAMESPACE
 
 namespace QScript
 {
 
-class QVariantWrapperObject : public JSC::JSObject
+class QVariantDelegate : public QScriptObjectDelegate
 {
 public:
-     // work around CELL_SIZE limitation
-    struct Data
-    {
-        QVariant value;
-    };
+    QVariantDelegate(const QVariant &value);
+    ~QVariantDelegate();
 
-    explicit QVariantWrapperObject(WTF::PassRefPtr<JSC::Structure> sid);
-    ~QVariantWrapperObject();
-    
-    virtual const JSC::ClassInfo* classInfo() const { return &info; }
-    static const JSC::ClassInfo info;
+    QVariant &value();
+    void setValue(const QVariant &value);
 
-    inline QVariant &value() const { return data->value; }
-    inline void setValue(const QVariant &value) { data->value = value; }
+    Type type() const;
 
 private:
-    Data *data;
+    QVariant m_value;
 };
 
-class QVariantPrototype : public QVariantWrapperObject
+class QVariantPrototype : public QScriptObject
 {
 public:
     QVariantPrototype(JSC::ExecState*, WTF::PassRefPtr<JSC::Structure>,