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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/core/v8/DOMWrapperWorld.h"
     35 #include "bindings/core/v8/ScopedPersistent.h"
     36 #include "core/events/EventListener.h"
     37 #include "wtf/PassRefPtr.h"
     38 #include "wtf/RefCounted.h"
     39 #include <v8.h>
     40 
     41 namespace blink {
     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>);
    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 blink
    157 
    158 #endif // V8AbstractEventListener_h
    159