001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *     http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.jxpath.servlet;
018
019import org.apache.commons.jxpath.Variables;
020
021/**
022 * Implementation of the Variables interface that provides access
023 * to a single object using a reserved name (keyword).
024 *
025 * @author Dmitri Plotnikov
026 * @version $Revision: 652925 $ $Date: 2008-05-03 00:05:41 +0200 (Sa, 03 Mai 2008) $
027 */
028public class KeywordVariables implements Variables {
029    private static final long serialVersionUID = 894145608741325442L;
030
031    private String keyword;
032    private Object object;
033
034    /**
035     * Create a new KeywordVariables.
036     * @param keyword String
037     * @param object value
038     */
039    public KeywordVariables(String keyword, Object object) {
040        if (keyword == null) {
041            throw new IllegalArgumentException("keyword cannot be null");
042        }
043        this.keyword = keyword;
044        this.object = object;
045    }
046
047    public boolean isDeclaredVariable(String variable) {
048        return variable.equals(keyword);
049    }
050
051    public Object getVariable(String variable) {
052        return isDeclaredVariable(variable) ? object : null;
053    }
054
055    public void declareVariable(String variable, Object value) {
056        throw new UnsupportedOperationException(
057            "Cannot declare new keyword variables.");
058    }
059
060    public void undeclareVariable(String variable) {
061        throw new UnsupportedOperationException(
062            "Cannot undeclare keyword variables.");
063    }
064}