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 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

 /* This Source Code Form is subject to the terms of the Mozilla Public

  * License, v. 2.0. If a copy of the MPL was not distributed with this

  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

 #ifndef mozilla_JSEventHandler_h_

 #define mozilla_JSEventHandler_h_

 #include "mozilla/Attributes.h"

 #include "mozilla/MemoryReporting.h"

 #include "mozilla/dom/EventHandlerBinding.h"

 #include "nsCOMPtr.h"

 #include "nsCycleCollectionParticipant.h"

 #include "nsIAtom.h"

 #include "nsIDOMKeyEvent.h"

 #include "nsIDOMEventListener.h"

 #include "nsIScriptContext.h"

 namespace mozilla {

 class TypedEventHandler

 {

 public:

   enum HandlerType

   {

     eUnset = 0,

     eNormal = 0x1,

     eOnError = 0x2,

     eOnBeforeUnload = 0x3,

     eTypeBits = 0x3

   };

   TypedEventHandler()

     : mBits(0)

   {

   }

   TypedEventHandler(dom::EventHandlerNonNull* aHandler)

   {

     Assign(aHandler, eNormal);

   }

   TypedEventHandler(dom::OnErrorEventHandlerNonNull* aHandler)

   {

     Assign(aHandler, eOnError);

   }

   TypedEventHandler(dom::OnBeforeUnloadEventHandlerNonNull* aHandler)

   {

     Assign(aHandler, eOnBeforeUnload);

   }

   TypedEventHandler(const TypedEventHandler& aOther)

   {

     if (aOther.HasEventHandler()) {

       // Have to make sure we take our own ref

       Assign(aOther.Ptr(), aOther.Type());

     } else {

       mBits = 0;

     }

   }

   ~TypedEventHandler()

   {

     ReleaseHandler();

   }

   HandlerType Type() const

   {

     return HandlerType(mBits & eTypeBits);

   }

   bool HasEventHandler() const

   {

     return !!Ptr();

   }

   void SetHandler(const TypedEventHandler& aHandler)

   {

     if (aHandler.HasEventHandler()) {

       ReleaseHandler();

       Assign(aHandler.Ptr(), aHandler.Type());

     } else {

       ForgetHandler();

     }

   }

   dom::EventHandlerNonNull* NormalEventHandler() const

   {

     MOZ_ASSERT(Type() == eNormal && Ptr());

     return reinterpret_cast<dom::EventHandlerNonNull*>(Ptr());

   }

   void SetHandler(dom::EventHandlerNonNull* aHandler)

   {

     ReleaseHandler();

     Assign(aHandler, eNormal);

   }

   dom::OnBeforeUnloadEventHandlerNonNull* OnBeforeUnloadEventHandler() const

   {

     MOZ_ASSERT(Type() == eOnBeforeUnload);

     return reinterpret_cast<dom::OnBeforeUnloadEventHandlerNonNull*>(Ptr());

   }

   void SetHandler(dom::OnBeforeUnloadEventHandlerNonNull* aHandler)

   {

     ReleaseHandler();

     Assign(aHandler, eOnBeforeUnload);

   }

   dom::OnErrorEventHandlerNonNull* OnErrorEventHandler() const

   {

     MOZ_ASSERT(Type() == eOnError);

     return reinterpret_cast<dom::OnErrorEventHandlerNonNull*>(Ptr());

   }

   void SetHandler(dom::OnErrorEventHandlerNonNull* aHandler)

   {

     ReleaseHandler();

     Assign(aHandler, eOnError);

   }

   dom::CallbackFunction* Ptr() const

   {

     // Have to cast eTypeBits so we don't have to worry about

     // promotion issues after the bitflip.

     return reinterpret_cast<dom::CallbackFunction*>(mBits &

                                                       ~uintptr_t(eTypeBits));

   }

   void ForgetHandler()

   {

     ReleaseHandler();

     mBits = 0;

   }

   bool operator==(const TypedEventHandler& aOther) const

   {

     return

       Ptr() && aOther.Ptr() &&

       Ptr()->CallbackPreserveColor() == aOther.Ptr()->CallbackPreserveColor();

   }

 private:

   void operator=(const TypedEventHandler&) MOZ_DELETE;

   void ReleaseHandler()

   {

     nsISupports* ptr = Ptr();

     NS_IF_RELEASE(ptr);

   }

   void Assign(nsISupports* aHandler, HandlerType aType)

   {

     MOZ_ASSERT(aHandler, "Must have handler");

     NS_ADDREF(aHandler);

     mBits = uintptr_t(aHandler) | uintptr_t(aType);

   }

   uintptr_t mBits;

 };

 /**

  * Implemented by script event listeners. Used to retrieve the script object

  * corresponding to the event target and the handler itself.

  *

  * Note, mTarget is a raw pointer and the owner of the JSEventHandler object

  * is expected to call Disconnect()!

  */

 #define NS_JSEVENTHANDLER_IID \

 { 0x4f486881, 0x1956, 0x4079, \

   { 0x8c, 0xa0, 0xf3, 0xbd, 0x60, 0x5c, 0xc2, 0x79 } }

 class JSEventHandler : public nsIDOMEventListener

 {

 public:

   NS_DECLARE_STATIC_IID_ACCESSOR(NS_JSEVENTHANDLER_IID)

   JSEventHandler(nsISupports* aTarget, nsIAtom* aType,

                  const TypedEventHandler& aTypedHandler);

   virtual ~JSEventHandler();

   NS_DECL_CYCLE_COLLECTING_ISUPPORTS

   // nsIDOMEventListener interface

   NS_DECL_NSIDOMEVENTLISTENER

   nsISupports* GetEventTarget() const

   {

     return mTarget;

   }

   void Disconnect()

   {

     mTarget = nullptr;

   }

   const TypedEventHandler& GetTypedEventHandler() const

   {

     return mTypedHandler;

   }

   void ForgetHandler()

   {

     mTypedHandler.ForgetHandler();

   }

   nsIAtom* EventName() const

   {

     return mEventName;

   }

   // Set a handler for this event listener.  The handler must already

   // be bound to the right target.

   void SetHandler(const TypedEventHandler& aTypedHandler)

   {

     mTypedHandler.SetHandler(aTypedHandler);

   }

   void SetHandler(dom::EventHandlerNonNull* aHandler)

   {

     mTypedHandler.SetHandler(aHandler);

   }

   void SetHandler(dom::OnBeforeUnloadEventHandlerNonNull* aHandler)

   {

     mTypedHandler.SetHandler(aHandler);

   }

   void SetHandler(dom::OnErrorEventHandlerNonNull* aHandler)

   {

     mTypedHandler.SetHandler(aHandler);

   }

   size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const

   {

     return 0;

     // Measurement of the following members may be added later if DMD finds it

     // is worthwhile:

     // - mTarget

     //

     // The following members are not measured:

     // - mTypedHandler: may be shared with others

     // - mEventName: shared with others

   }

   size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf)

   {

     return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);

   }

   NS_DECL_CYCLE_COLLECTION_SKIPPABLE_CLASS(JSEventHandler)

   bool IsBlackForCC();

 protected:

   nsISupports* mTarget;

   nsCOMPtr<nsIAtom> mEventName;

   TypedEventHandler mTypedHandler;

 };

 NS_DEFINE_STATIC_IID_ACCESSOR(JSEventHandler, NS_JSEVENTHANDLER_IID)

 } // namespace mozilla

 /**

  * Factory function.  aHandler must already be bound to aTarget.

  * aContext is allowed to be null if aHandler is already set up.

  */

 nsresult NS_NewJSEventHandler(nsISupports* aTarget,

                               nsIAtom* aType,

                               const mozilla::TypedEventHandler& aTypedHandler,

                               mozilla::JSEventHandler** aReturn);

 #endif // mozilla_JSEventHandler_h_