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      1 /*
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     28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     29  */
     30 
     31 #ifndef V8AbstractEventListener_h
     32 #define V8AbstractEventListener_h
     33 
     34 #include "bindings/v8/DOMWrapperWorld.h"
     35 #include "bindings/v8/ScopedPersistent.h"
     36 #include "bindings/v8/V8Utilities.h"
     37 #include "core/events/EventListener.h"
     38 #include <v8.h>
     39 #include "wtf/PassRefPtr.h"
     40 #include "wtf/RefCounted.h"
     41 
     42 namespace WebCore {
     43 
     44     class Event;
     45 
     46     // There are two kinds of event listeners: HTML or non-HMTL. onload,
     47     // onfocus, etc (attributes) are always HTML event handler type; Event
     48     // listeners added by Window.addEventListener or
     49     // EventTargetNode::addEventListener are non-HTML type.
     50     //
     51     // Why does this matter?
     52     // WebKit does not allow duplicated HTML event handlers of the same type,
     53     // but ALLOWs duplicated non-HTML event handlers.
     54     class V8AbstractEventListener : public EventListener {
     55     public:
     56         virtual ~V8AbstractEventListener();
     57 
     58         static const V8AbstractEventListener* cast(const EventListener* listener)
     59         {
     60             return listener->type() == JSEventListenerType
     61                 ? static_cast<const V8AbstractEventListener*>(listener)
     62                 : 0;
     63         }
     64 
     65         static V8AbstractEventListener* cast(EventListener* listener)
     66         {
     67             return const_cast<V8AbstractEventListener*>(cast(const_cast<const EventListener*>(listener)));
     68         }
     69 
     70         // Implementation of EventListener interface.
     71 
     72         virtual bool operator==(const EventListener& other) { return this == &other; }
     73 
     74         virtual void handleEvent(ExecutionContext*, Event*);
     75 
     76         virtual bool isLazy() const { return false; }
     77 
     78         // Returns the listener object, either a function or an object.
     79         v8::Local<v8::Object> getListenerObject(ExecutionContext* context)
     80         {
     81             // prepareListenerObject can potentially deref this event listener
     82             // as it may attempt to compile a function (lazy event listener), get an error
     83             // and invoke onerror callback which can execute arbitrary JS code.
     84             // Protect this event listener to keep it alive.
     85             RefPtr<V8AbstractEventListener> guard(this);
     86             prepareListenerObject(context);
     87             return m_listener.newLocal(m_isolate);
     88         }
     89 
     90         v8::Local<v8::Object> getExistingListenerObject()
     91         {
     92             return m_listener.newLocal(m_isolate);
     93         }
     94 
     95         // Provides access to the underlying handle for GC. Returned
     96         // value is a weak handle and so not guaranteed to stay alive.
     97         v8::Persistent<v8::Object>& existingListenerObjectPersistentHandle()
     98         {
     99             return m_listener.getUnsafe();
    100         }
    101 
    102         bool hasExistingListenerObject()
    103         {
    104             return !m_listener.isEmpty();
    105         }
    106 
    107         void clearListenerObject()
    108         {
    109             m_listener.clear();
    110         }
    111 
    112         virtual DOMWrapperWorld* world() const OVERRIDE FINAL { return m_world.get(); }
    113         v8::Isolate* isolate() const { return m_isolate; }
    114 
    115     protected:
    116         V8AbstractEventListener(bool isAttribute, PassRefPtr<DOMWrapperWorld>, v8::Isolate*);
    117 
    118         virtual void prepareListenerObject(ExecutionContext*) { }
    119 
    120         void setListenerObject(v8::Handle<v8::Object> listener);
    121 
    122         void invokeEventHandler(ExecutionContext*, Event*, v8::Local<v8::Value> jsEvent);
    123 
    124         // Get the receiver object to use for event listener call.
    125         v8::Local<v8::Object> getReceiverObject(ExecutionContext*, Event*);
    126 
    127     private:
    128         // Implementation of EventListener function.
    129         virtual bool virtualisAttribute() const { return m_isAttribute; }
    130 
    131         virtual v8::Local<v8::Value> callListenerFunction(ExecutionContext*, v8::Handle<v8::Value> jsevent, Event*) = 0;
    132 
    133         virtual bool shouldPreventDefault(v8::Local<v8::Value> returnValue);
    134 
    135         static void setWeakCallback(const v8::WeakCallbackData<v8::Object, V8AbstractEventListener>&);
    136 
    137         ScopedPersistent<v8::Object> m_listener;
    138 
    139         // Indicates if this is an HTML type listener.
    140         bool m_isAttribute;
    141 
    142         RefPtr<DOMWrapperWorld> m_world;
    143         v8::Isolate* m_isolate;
    144     };
    145 
    146 } // namespace WebCore
    147 
    148 #endif // V8AbstractEventListener_h
    149