DMDirc-Util/src/com/dmdirc/util/ListenerList.java

/*
 * Copyright (c) 2006-2010 Chris Smith, Shane Mc Cormack, Gregory Holmes
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

package com.dmdirc.util;

import java.util.Collection;
import java.util.Comparator;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.ConcurrentSkipListSet;

/**
 * Represents a list of event listeners, similar to EventListenerList, but
 * not swing specific.
 * 
 * @author chris
 */
public class ListenerList {

    /** The comparator to use. */
    protected static EqualComparator COMPARATOR = new EqualComparator();
    
    /** The map of class->listener or string->listener that we're using. */
    private final Map<Object, Collection<Object>> listeners
            = new HashMap<Object, Collection<Object>>();
    
    /**
     * Creates a new instance of ListenerList.
     */
    public ListenerList() {
        // Do nothing
    }
    
    /**
     * Adds a new listener of the specified type to this listener list.
     * 
     * @param listenerType The type of listener to be added
     * @param listener The listener to be added
     */
    public <T> void add(final Class<T> listenerType, final T listener) {
        if (!listeners.containsKey(listenerType)) {
            listeners.put(listenerType, new ConcurrentSkipListSet<Object>(COMPARATOR));
        }

        listeners.get(listenerType).add(listener);
    }
    
    /**
     * Adds a new listener of the specified type to this listener list.
     * 
     * @param listenerType The name of the type of listener that's being added
     * @param listener The listener to be added
     */
    public void add(final String listenerType, final Object listener) {
        if (!listeners.containsKey(listenerType)) {
            listeners.put(listenerType, new ConcurrentSkipListSet<Object>(COMPARATOR));
        }

        listeners.get(listenerType).add(listener);
    }
    
    /**
     * Removes the specified listener from the list of listeners for the
     * specified type.
     * 
     * @param listenerType The type that the listener should be removed from
     * @param listener The listener to be removed
     */
    public <T> void remove(final Class<T> listenerType, final T listener) {
        listeners.get(listenerType).remove(listener);
    }
    
    /**
     * Removes the specified listener from the list of listeners for the
     * specified type.
     * 
     * @param listenerType The name of the type that the listener should be
     * removed from
     * @param listener The listener to be removed
     */
    public void remove(final String listenerType, final Object listener) {
        listeners.get(listenerType).remove(listener);
    }
    
    /**
     * Retrieves the list of listeners for the specified type.
     * 
     * @param listenerType The type of listener that's being retrieved
     * @return A list of listeners for the specified type
     */
    @SuppressWarnings("unchecked")
    public <T> Collection<T> get(final Class<T> listenerType) {
        if (listeners.containsKey(listenerType)) {
            return (Collection<T>) listeners.get(listenerType);
        } else {
            return new ConcurrentSkipListSet<T>(COMPARATOR);
        }
    }
    
    /**
     * Retrieves the list of listeners for the specified type.
     * 
     * @param listenerType The type of listener to be retrieved
     * @return A list of listeners for the specified type
     */
    public Collection<Object> get(final String listenerType) {
        if (listeners.containsKey(listenerType)) {
            return listeners.get(listenerType);
        } else {
            return new ConcurrentSkipListSet<Object>(COMPARATOR);
        }
    }

    /**
     * A comparator that says any two objects are equal.
     *
     * @since 0.6.4
     */
    protected static class EqualComparator implements Comparator<Object> {

        /** {@inheritDoc} */
        @Override
        public int compare(final Object o1, final Object o2) {
            return 0;
        }

    }

}