add original source

source/listing_c.4.cpp

@@ -0,0 +1,65 @@
+namespace messaging
+{
+    class close_queue
+    {};
+
+    class dispatcher
+    {
+        queue* q;
+        bool chained;
+
+        dispatcher(dispatcher const&)=delete;
+        dispatcher& operator=(dispatcher const&)=delete;
+
+        template<
+            typename Dispatcher,
+            typename Msg,
+            typename Func>
+        friend class TemplateDispatcher;
+
+        void wait_and_dispatch()
+        {
+            for(;;)
+            {
+                auto msg=q->wait_and_pop();
+                dispatch(msg);
+            }
+        }
+
+        bool dispatch(
+            std::shared_ptr<message_base> const& msg)
+        {
+            if(dynamic_cast<wrapped_message<close_queue>*>(msg.get()))
+            {
+                throw close_queue();
+            }
+            return false;
+        }
+    public:
+        dispatcher(dispatcher&& other):
+            q(other.q),chained(other.chained)
+        {
+            other.chained=true;
+        }
+
+        explicit dispatcher(queue* q_):
+            q(q_),chained(false)
+        {}
+
+        template<typename Message,typename Func>
+        TemplateDispatcher<dispatcher,Message,Func>
+        handle(Func&& f)
+        {
+            return TemplateDispatcher<dispatcher,Message,Func>(
+                q,this,std::forward<Func>(f));
+        }
+
+        ~dispatcher() noexcept(false)
+        {
+            if(!chained)
+            {
+                wait_and_dispatch();
+            }
+        }
+    };
+}