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
015package org.apache.tapestry5.internal.services;
016
017import org.apache.tapestry5.ioc.MessageFormatter;
018import 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 */
027public 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}