001/*
002 *  Licensed to the Apache Software Foundation (ASF) under one
003 *  or more contributor license agreements.  See the NOTICE file
004 *  distributed with this work for additional information
005 *  regarding copyright ownership.  The ASF licenses this file
006 *  to you under the Apache License, Version 2.0 (the
007 *  "License"); you may not use this file except in compliance
008 *  with the License.  You may obtain a copy of the License at
009 *
010 *    http://www.apache.org/licenses/LICENSE-2.0
011 *
012 *  Unless required by applicable law or agreed to in writing,
013 *  software distributed under the License is distributed on an
014 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 *  KIND, either express or implied.  See the License for the
016 *  specific language governing permissions and limitations
017 *  under the License.
018 *
019 */
020package org.apache.mina.statemachine.context;
021
022/**
023 * {@link StateContextLookup} implementation which always returns the same
024 * {@link StateContext} instance.
025 *
026 * @author <a href="http://mina.apache.org">Apache MINA Project</a>
027 */
028public class SingletonStateContextLookup implements StateContextLookup {
029    private final StateContext context;
030
031    /**
032     * Creates a new instance which always returns the same 
033     * {@link DefaultStateContext} instance.
034     */
035    public SingletonStateContextLookup() {
036        context = new DefaultStateContext();
037    }
038
039    /**
040     * Creates a new instance which uses the specified {@link StateContextFactory}
041     * to create the single instance.
042     * 
043     * @param contextFactory the {@link StateContextFactory} to use to create 
044     *        the singleton instance.
045     */
046    public SingletonStateContextLookup(StateContextFactory contextFactory) {
047        if (contextFactory == null) {
048            throw new IllegalArgumentException("contextFactory");
049        }
050        context = contextFactory.create();
051    }
052
053    public StateContext lookup(Object[] eventArgs) {
054        return context;
055    }
056}