ui-dispatcher.hpp

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/*
  UI-DISPATCHER.hpp  -  dispatch invocations into the UI event thread

   Copyright (C)
     2017,            Hermann Vosseler <Ichthyostega@web.de>

  **Lumiera** is free software; you can redistribute it and/or modify it
  under the terms of the GNU General Public License as published by the
  Free Software Foundation; either version 2 of the License, or (at your
  option) any later version. See the file COPYING for further details.

*/


#ifndef STAGE_CTRL_UI_DISPATCHER_H
#define STAGE_CTRL_UI_DISPATCHER_H

#include "stage/gtk-base.hpp"
#include "lib/call-queue.hpp"
#include "lib/format-string.hpp"
#include "lib/nocopy.hpp"

#include <utility>


namespace stage {
namespace ctrl {
  
  using std::move;
  using ::util::_Fmt;
  
  namespace {
    inline string
    generateErrorResponse (const char* problem = "unexpected problem")
    {
      static _Fmt messageTemplate{"asynchronous UI response failed: %s (error flag was: %s)"};
      string response{messageTemplate % problem % lumiera_error()};
      WARN (stage, "%s", response.c_str());
      return response;
    }
  }
  
  
  class UiDispatcher
    : util::NonCopyable
    {
      lib::CallQueue queue_;
      Glib::Dispatcher dispatcher_;
      
      using Operation = lib::CallQueue::Operation;
      
    public:
      template<class FUN>
      UiDispatcher(FUN notification)
        : queue_{}
        , dispatcher_{}
        {
          dispatcher_.connect(
                         [=]() {try {
                                      queue_.invoke();
                                    }
                                  catch (std::exception& problem)
                                    {
                                      notification (generateErrorResponse(problem.what()));
                                    }
                                  catch (...)
                                    {
                                      notification (generateErrorResponse());
                                    }
                               });
        }
      
      void
      event (Operation&& op)
        {
          queue_.feed (move(op));
          dispatcher_.emit();
        }
    };
  
  
  
}}// namespace stage::ctrl
#endif /*STAGE_CTRL_UI_DISPATCHER_H*/