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 *
017 */
018
019package org.apache.commons.exec.util;
020
021import java.util.Map;
022import java.util.HashMap;
023import java.util.Iterator;
024
025/**
026 * Helper classes to manipulate maps to pass substition map to the
027 * CommandLine. This class is not part of the public API and
028 * could change without warning.
029 *
030 * @author <a href="mailto:siegfried.goeschl@it20one.at">Siegfried Goeschl</a>
031 */
032public class MapUtils
033{
034    /**
035     * Clones a map.
036     *
037     * @param source the source map
038     * @return the clone of the source map
039     */
040    public static Map copy(Map source) {
041
042        if(source == null) {
043            return null;
044        }
045
046        Map result = new HashMap();
047        result.putAll(source);
048        return result;
049    }
050
051    /**
052     * Clones a map and prefixes the keys in the clone, e.g.
053     * for mapping "JAVA_HOME" to "env.JAVA_HOME" to simulate
054     * the behaviour of ANT.
055     *
056     * @param source the source map
057     * @param prefix the prefix used for all names
058     * @return the clone of the source map
059     */
060    public static Map prefix(Map source, String prefix) {
061
062        if(source == null) {
063            return null;
064        }
065
066        Map result = new HashMap();
067
068        Iterator iter = source.entrySet().iterator();
069
070        while(iter.hasNext()) {
071            Map.Entry entry = (Map.Entry) iter.next();
072            Object key = entry.getKey();
073            Object value = entry.getValue();
074            result.put(prefix + '.' + key.toString(), value);
075        }
076
077        return result;
078    }
079
080    /**
081     * Clones the lhs map and add all things from the
082     * rhs map.
083     *
084     * @param lhs the first map
085     * @param rhs the second map
086     * @return the merged map
087     */
088    public static Map merge(Map lhs, Map rhs) {
089
090        Map result = null;
091
092        if((lhs == null) || (lhs.size() == 0)) {
093            result = copy(rhs);
094        }
095        else if((rhs == null) || (rhs.size() == 0)) {
096            result = copy(lhs);
097        }
098        else {
099            result = copy(lhs);
100            result.putAll(rhs);
101        }
102        
103        return result;
104    }
105}