git subrepo clone --branch=20.41.6 git@github.com:ETLCPP/etl.git components/etl

subrepo:
  subdir:   "components/etl"
  merged:   "be5537ec"
upstream:
  origin:   "git@github.com:ETLCPP/etl.git"
  branch:   "20.41.6"
  commit:   "be5537ec"
git-subrepo:
  version:  "0.4.9"
  origin:   "???"
  commit:   "???"

components/etl/examples/QueuedMessageRouter/QueuedMessageRouter.cpp

@@ -0,0 +1,149 @@
+
+#include "etl/queue.h"
+#include "etl/message_router.h"
+
+#include <iostream>
+#include <string>
+
+//*****************************************************************************
+// The messages.
+//*****************************************************************************
+struct Message1 : public etl::message<1>
+{
+  Message1(int i_)
+    : i(i_)
+  {
+  }
+
+  int i;
+};
+
+struct Message2 : public etl::message<2>
+{
+  Message2(double d_)
+    : d(d_)
+  {
+  }
+
+  double d;
+};
+
+struct Message3 : public etl::message<3>
+{
+  Message3(const std::string& s_)
+    : s(s_)
+  {
+  }
+
+  std::string s;
+};
+
+struct Message4 : public etl::message<4>
+{
+};
+
+//*****************************************************************************
+// The message router.
+// Handles message types Message1, Message2, Message3.
+//*****************************************************************************
+class Router : public etl::message_router<Router, Message1, Message2, Message3>
+{
+public:
+
+  typedef etl::message_router<Router, Message1, Message2, Message3> Base_t;
+
+  //***************************************************************************
+  Router()
+    : message_router(1)
+  {
+  }
+
+  //***************************************************************************
+  // Override the base class's receive function.
+  void receive(const etl::imessage& msg_)
+  {
+    if (accepts(msg_))
+    {
+      // Place in queue.
+      queue.emplace(msg_);
+
+      std::cout << "Queueing message " << int(msg_.get_message_id()) << std::endl;
+    }
+    else
+    {
+      std::cout << "Ignoring message " << int(msg_.get_message_id()) << std::endl;
+    }
+  }
+
+  //***************************************************************************
+  void process_queue()
+  {
+    while (!queue.empty())
+    {
+      message_packet& packet = queue.front();
+      etl::imessage& msg = packet.get();
+      std::cout << "Processing message " << int(msg.get_message_id()) << std::endl;
+
+      // Call the base class's receive function.
+      // This will route it to the correct on_receive handler.
+      Base_t::receive(msg);
+
+      queue.pop();
+    }
+  }
+
+  //***************************************************************************
+  void on_receive(const Message1& msg)
+  {
+    std::cout << "  Received message " << int(msg.get_message_id()) << " : '" << msg.i << "'" << std::endl;
+  }
+
+  //***************************************************************************
+  void on_receive(const Message2& msg)
+  {
+    std::cout << "  Received message " << int(msg.get_message_id()) << " : '" << msg.d << "'" << std::endl;
+  }
+
+  //***************************************************************************
+  void on_receive(const Message3& msg)
+  {
+    std::cout << "  Received message " << int(msg.get_message_id()) << " : '" << msg.s << "'" << std::endl;
+  }
+
+  //***************************************************************************
+  void on_receive_unknown(const etl::imessage& msg)
+  {
+    std::cout << "  Received unknown message " << int(msg.get_message_id()) << std::endl;
+  }
+
+private:
+
+  etl::queue<message_packet, 10> queue;
+};
+
+//*****************************************************************************
+// The test application.
+//*****************************************************************************
+int main()
+{
+  Router router;
+
+  Message1 m1(1);
+  Message2 m2(1.2);
+  Message3 m3("Hello");
+
+  etl::send_message(router, m1);
+  etl::send_message(router, Message1(2));
+  etl::send_message(router, m2);
+  etl::send_message(router, Message2(3.4));
+  etl::send_message(router, m3);
+  etl::send_message(router, Message3("World"));
+  etl::send_message(router, Message4());
+
+  std::cout << std::endl;
+
+  router.process_queue();
+
+  return 0;
+}
+