Informer.cc

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/*
    Copyright (c) 2002-2009 Tampere University.
 
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/**
 * @file Informer.cc
 *
 * Implementation of Informer class.
 *
 * @author Atte Oksman 2005 (oksman-no.spam-cs.tut.fi)
 * @author Pekka Jääskeläinen 2005 (pjaaskel-no.spam-cs.tut.fi)
 * @note rating: red
 */
 
#include <utility>
 
#include "Informer.hh"
#include "Listener.hh"
#include "Application.hh"
 
 
/**
 * Constructor.
 */
Informer::Informer() {
}
 
 
/**
 * Destructor.
 */
Informer::~Informer() {
}
 
/**
 * Finds the event slot for the given listener listening to the given event.
 *
 * In case the listener is not found, it's added to the list and index of
 * it is returned.
 *
 * @param event Event the listener is listening to.
 * @param listener The listener.
 * @return The index of the event slot.
 */
inline std::size_t
Informer::findListenerSlot(int event, Listener* listener) {
    for (std::size_t i = 0; i < eventListeners_.size(); ++i) {
        if (eventListeners_.at(i).first == event &&
            eventListeners_.at(i).second == listener) {
            return i;
        }
    }
    eventListeners_.push_back(std::make_pair(event, listener));
    return eventListeners_.size() - 1;
}
 
/**
 * Adds the given Listener to the list of listeners of the given event.
 *
 * After this function has been called, the listener will be notified every
 * time the event occurs.
 *
 * @param event The code identifying the event.
 * @param listener The Listener that should be added.
 * @return 'True' if adding of the listener succeeds, 'false' otherwise.
 */
bool
Informer::registerListener(int event, Listener* listener) {
    findListenerSlot(event, listener);
    return true;
}
 
 
/**
 * Removes the given Listener from the list of listeners of the given event.
 *
 * After this function has been called, the listener will not be notified
 * that the event has occurred.
 *
 * @param event The code identifying the event.
 * @param listener The Listener that should be removed.
 * @return 'True' if removing the listener succeeds, 'false' otherwise.
 */
bool
Informer::unregisterListener(int event, Listener* listener) {
    std::size_t index = findListenerSlot(event, listener);
    ListenerList::iterator i = eventListeners_.begin() + index;
    eventListeners_.erase(i);
    return true;
}