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      1 /*
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     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 "core/events/EventListener.h"
     37 #include <v8.h>
     38 #include "wtf/PassRefPtr.h"
     39 #include "wtf/RefCounted.h"
     40 
     41 namespace WebCore {
     42 
     43     class Event;
     44 
     45     // There are two kinds of event listeners: HTML or non-HMTL. onload,
     46     // onfocus, etc (attributes) are always HTML event handler type; Event
     47     // listeners added by Window.addEventListener or
     48     // EventTargetNode::addEventListener are non-HTML type.
     49     //
     50     // Why does this matter?
     51     // WebKit does not allow duplicated HTML event handlers of the same type,
     52     // but ALLOWs duplicated non-HTML event handlers.
     53     class V8AbstractEventListener : public EventListener {
     54     public:
     55         virtual ~V8AbstractEventListener();
     56 
     57         static const V8AbstractEventListener* cast(const EventListener* listener)
     58         {
     59             return listener->type() == JSEventListenerType
     60                 ? static_cast<const V8AbstractEventListener*>(listener)
     61                 : 0;
     62         }
     63 
     64         static V8AbstractEventListener* cast(EventListener* listener)
     65         {
     66             return const_cast<V8AbstractEventListener*>(cast(const_cast<const EventListener*>(listener)));
     67         }
     68 
     69         // Implementation of EventListener interface.
     70 
     71         virtual bool operator==(const EventListener& other) OVERRIDE { return this == &other; }
     72 
     73         virtual void handleEvent(ExecutionContext*, Event*) OVERRIDE;
     74 
     75         virtual bool isLazy() const { return false; }
     76 
     77         // Returns the listener object, either a function or an object.
     78         v8::Local<v8::Object> getListenerObject(ExecutionContext* context)
     79         {
     80             // prepareListenerObject can potentially deref this event listener
     81             // as it may attempt to compile a function (lazy event listener), get an error
     82             // and invoke onerror callback which can execute arbitrary JS code.
     83             // Protect this event listener to keep it alive.
     84             RefPtr<V8AbstractEventListener> guard(this);
     85             prepareListenerObject(context);
     86             return m_listener.newLocal(m_isolate);
     87         }
     88 
     89         v8::Local<v8::Object> getExistingListenerObject()
     90         {
     91             return m_listener.newLocal(m_isolate);
     92         }
     93 
     94         // Provides access to the underlying handle for GC. Returned
     95         // value is a weak handle and so not guaranteed to stay alive.
     96         v8::Persistent<v8::Object>& existingListenerObjectPersistentHandle()
     97         {
     98             return m_listener.getUnsafe();
     99         }
    100 
    101         bool hasExistingListenerObject()
    102         {
    103             return !m_listener.isEmpty();
    104         }
    105 
    106         void clearListenerObject()
    107         {
    108             m_listener.clear();
    109         }
    110 
    111         virtual bool belongsToTheCurrentWorld() const OVERRIDE FINAL;
    112         v8::Isolate* isolate() const { return m_isolate; }
    113         virtual DOMWrapperWorld& world() const { return scriptState()->world(); }
    114         ScriptState* scriptState() const
    115         {
    116             ASSERT(m_scriptState);
    117             return m_scriptState.get();
    118         }
    119         void setScriptState(ScriptState* scriptState) { m_scriptState = scriptState; }
    120 
    121     protected:
    122         V8AbstractEventListener(bool isAttribute, ScriptState*);
    123         V8AbstractEventListener(bool isAttribute, v8::Isolate*);
    124 
    125         virtual void prepareListenerObject(ExecutionContext*) { }
    126 
    127         void setListenerObject(v8::Handle<v8::Object> listener);
    128 
    129         void invokeEventHandler(Event*, v8::Local<v8::Value> jsEvent);
    130 
    131         // Get the receiver object to use for event listener call.
    132         v8::Local<v8::Object> getReceiverObject(Event*);
    133 
    134     private:
    135         // Implementation of EventListener function.
    136         virtual bool virtualisAttribute() const OVERRIDE { return m_isAttribute; }
    137 
    138         virtual v8::Local<v8::Value> callListenerFunction(v8::Handle<v8::Value> jsevent, Event*) = 0;
    139 
    140         virtual bool shouldPreventDefault(v8::Local<v8::Value> returnValue);
    141 
    142         static void setWeakCallback(const v8::WeakCallbackData<v8::Object, V8AbstractEventListener>&);
    143 
    144         ScopedPersistent<v8::Object> m_listener;
    145 
    146         // Indicates if this is an HTML type listener.
    147         bool m_isAttribute;
    148 
    149         // For V8LazyEventListener, m_scriptState can be 0 until V8LazyEventListener is actually used.
    150         // m_scriptState is set lazily because V8LazyEventListener doesn't know the associated frame
    151         // until the listener is actually used.
    152         RefPtr<ScriptState> m_scriptState;
    153         v8::Isolate* m_isolate;
    154     };
    155 
    156 } // namespace WebCore
    157 
    158 #endif // V8AbstractEventListener_h
    159