/*
  ==============================================================================

   This file is part of the JUCE library.
   Copyright (c) 2017 - ROLI Ltd.

   JUCE is an open source library subject to commercial or open-source
   licensing.

   The code included in this file is provided under the terms of the ISC license
   http://www.isc.org/downloads/software-support-policy/isc-license. Permission
   To use, copy, modify, and/or distribute this software for any purpose with or
   without fee is hereby granted provided that the above copyright notice and
   this permission notice appear in all copies.

   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.

  ==============================================================================
*/

namespace juce
{

//==============================================================================
/**
    MessageListener subclasses can post and receive Message objects.

    @see Message, MessageManager, ActionListener, ChangeListener
*/
class JUCE_API  MessageListener
{
public:
    //==============================================================================
    MessageListener() noexcept;

    /** Destructor. */
    virtual ~MessageListener();

    //==============================================================================
    /** This is the callback method that receives incoming messages.

        This is called by the MessageManager from its dispatch loop.

        @see postMessage
    */
    virtual void handleMessage (const Message& message) = 0;

    //==============================================================================
    /** Sends a message to the message queue, for asynchronous delivery to this listener
        later on.

        This method can be called safely by any thread.

        @param message      the message object to send - this will be deleted
                            automatically by the message queue, so make sure it's
                            allocated on the heap, not the stack!
        @see handleMessage
    */
    void postMessage (Message* message) const;

private:
    WeakReference<MessageListener>::Master masterReference;
    friend class WeakReference<MessageListener>;
};

} // namespace juce
