pjs/ef/Utilities/General/SystemEvents.h

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2.2 KiB
C++

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
*
* The contents of this file are subject to the Netscape Public License
* Version 1.0 (the "NPL"); you may not use this file except in
* compliance with the NPL. You may obtain a copy of the NPL at
* http://www.mozilla.org/NPL/
*
* Software distributed under the NPL is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the NPL
* for the specific language governing rights and limitations under the
* NPL.
*
* The Initial Developer of this code under the NPL is Netscape
* Communications Corporation. Portions created by Netscape are
* Copyright (C) 1998 Netscape Communications Corporation. All Rights
* Reserved.
*/
// SystemEvents.h
//
// Scott M. Silver
//
// EventListener and EventBroadcaster which work together
// to distribute interesting events around a system.
class EventListener;
class EventBroadcaster
{
Vector<EventListener*> mListeners;
void addListener(EventListener& inListener) { mListeners.append(&inListener); }
void removeListener(EventListener& inListener) { }
void broadcastEvent(BroadcastEventKind inKind, void* inArgument);
static EventBroadcaster& checkAllocated(EventBroadcaster*& ioBroadcaster)
{
if (!ioBroadcaster)
ioBroadcaster = new EventBroadcaster();
return *ioBroadcaster;
}
public:
static void addListener(EventBroadcaster*& ioBroadcaster, EventListener& inListener)
{
checkAllocated(ioBroadcaster).addListener(inListener);
}
static void broadcastEvent(EventBroadcaster*& ioBroadcaster, BroadcastEventKind inKind, void* inArgument)
{
checkAllocated(ioBroadcaster).broadcastEvent(inKind, inArgument);
}
static void removeListener(EventBroadcaster*& ioBroadcaster, EventListener& inListener)
{
checkAllocated(ioBroadcaster).removeListener(inListener);
}
};
class EventListener
{
#ifdef DEBUG
Vector<EventBroadcaster*> mBroadcasters;
#endif
public:
EventListener(EventBroadcaster*& ioBroadcaster)
{
ioBroadcaster->addListener(ioBroadcaster, *this);
}
~EventListener() { }
virtual void listenToMessage(BroadcastEventKind inKind, void* inArgument) = 0;
};