/*
 *
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 *
 */
package org.apache.qpidity;

import java.util.HashMap;
import java.util.Map;

/**
 * A Switch performs generic event dispatch.
 *
 * @author Rafael H. Schloming
 */

abstract class Switch<K,E> implements Handler<E>
{

    final private Map<K,Handler<E>> handlers =
        new HashMap<K,Handler<E>>();

    public void map(K key, Handler<E> handler)
    {
        handlers.put(key, handler);
    }

    public void handle(E event)
    {
        K key = resolve(event);
        Handler<E> handler = handlers.get(key);
        if (handler == null)
        {
            throw new IllegalStateException("no such key: " + key +
                                            " this = " + this +
                                            " handlers = " + handlers);
        }
        handler.handle(event);
    }

    abstract K resolve(E event);

}
