    001    // Copyright 2010 The Apache Software Foundation
    002    //
    003    // Licensed under the Apache License, Version 2.0 (the "License");
    004    // you may not use this file except in compliance with the License.
    005    // You may obtain a copy of the License at
    006    //
    007    // http://www.apache.org/licenses/LICENSE-2.0
    008    //
    009    // Unless required by applicable law or agreed to in writing, software
    010    // distributed under the License is distributed on an "AS IS" BASIS,
    011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    012    // See the License for the specific language governing permissions and
    013    // limitations under the License.
    014
    015    package org.apache.tapestry5.internal.services;
    016
    017    import org.apache.tapestry5.ioc.MessageFormatter;
    018    import org.apache.tapestry5.ioc.Messages;
    019
    020    /**
    021     * Implementation of {@link Messages} that wraps two other Messages instances: a primary and a delegate.
    022     * The primary handles any keys it contains; method invocations that reference keys not contained by
    023     * the primary are passed on to the delegate.
    024     *
    025     * @since 5.2.0
    026     */
    027    public class DelegatingMessagesImpl implements Messages
    028    {
    029        private final Messages primary, delegate;
    030
    031        public DelegatingMessagesImpl(Messages primary, Messages delegate)
    032        {
    033            this.primary = primary;
    034            this.delegate = delegate;
    035        }
    036
    037        public boolean contains(String key)
    038        {
    039            return primary.contains(key) || delegate.contains(key);
    040        }
    041
    042        private Messages select(String key)
    043        {
    044            return primary.contains(key) ? primary : delegate;
    045        }
    046
    047        public String format(String key, Object... args)
    048        {
    049            return select(key).format(key, args);
    050        }
    051
    052        public String get(String key)
    053        {
    054            return select(key).get(key);
    055        }
    056
    057        public MessageFormatter getFormatter(String key)
    058        {
    059            return select(key).getFormatter(key);
    060        }
    061    }