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      1 /*
      2  * libjingle
      3  * Copyright 2004--2005, Google Inc.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions are met:
      7  *
      8  *  1. Redistributions of source code must retain the above copyright notice,
      9  *     this list of conditions and the following disclaimer.
     10  *  2. Redistributions in binary form must reproduce the above copyright notice,
     11  *     this list of conditions and the following disclaimer in the documentation
     12  *     and/or other materials provided with the distribution.
     13  *  3. The name of the author may not be used to endorse or promote products
     14  *     derived from this software without specific prior written permission.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
     17  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
     18  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
     19  * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     20  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     21  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
     22  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
     23  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
     24  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
     25  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     26  */
     27 
     28 #ifndef TALK_BASE_MESSAGEHANDLER_H_
     29 #define TALK_BASE_MESSAGEHANDLER_H_
     30 
     31 #include "talk/base/constructormagic.h"
     32 
     33 namespace talk_base {
     34 
     35 struct Message;
     36 
     37 // Messages get dispatched to a MessageHandler
     38 
     39 class MessageHandler {
     40  public:
     41   virtual ~MessageHandler();
     42   virtual void OnMessage(Message* msg) = 0;
     43 
     44  protected:
     45   MessageHandler() {}
     46 
     47  private:
     48   DISALLOW_COPY_AND_ASSIGN(MessageHandler);
     49 };
     50 
     51 // Helper class to facilitate executing a functor on a thread.
     52 template <class ReturnT, class FunctorT>
     53 class FunctorMessageHandler : public MessageHandler {
     54  public:
     55   explicit FunctorMessageHandler(const FunctorT& functor)
     56       : functor_(functor) {}
     57   virtual void OnMessage(Message* msg) {
     58     result_ = functor_();
     59   }
     60   const ReturnT& result() const { return result_; }
     61 
     62  private:
     63   FunctorT functor_;
     64   ReturnT result_;
     65 };
     66 
     67 // Specialization for ReturnT of void.
     68 template <class FunctorT>
     69 class FunctorMessageHandler<void, FunctorT> : public MessageHandler {
     70  public:
     71   explicit FunctorMessageHandler(const FunctorT& functor)
     72       : functor_(functor) {}
     73   virtual void OnMessage(Message* msg) {
     74     functor_();
     75   }
     76   void result() const {}
     77 
     78  private:
     79   FunctorT functor_;
     80 };
     81 
     82 
     83 } // namespace talk_base
     84 
     85 #endif // TALK_BASE_MESSAGEHANDLER_H_
     86