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.HashMap;
022import java.util.Map;
023
024/**
025 * Helper classes to manipulate maps to pass substition map to the CommandLine. This class is not part of the public API
026 * and could change without warning.
027 *
028 * @version $Id: MapUtils.java 1636205 2014-11-02 22:32:33Z ggregory $
029 */
030public class MapUtils
031{
032    /**
033     * Clones a map.
034     * 
035     * @param source
036     *            the Map to clone
037     * @param <K>
038     *            the map key type
039     * @param <V>
040     *            the map value type
041     * @return the cloned map
042     */
043   public static <K, V> Map<K, V> copy(final Map<K, V> source) {
044
045        if (source == null) {
046            return null;
047        }
048
049        final Map<K, V> result = new HashMap<K, V>();
050        result.putAll(source);
051        return result;
052    }
053
054    /**
055     * Clones a map and prefixes the keys in the clone, e.g. for mapping "JAVA_HOME" to "env.JAVA_HOME" to simulate the
056     * behaviour of Ant.
057     *
058     * @param source
059     *            the source map
060     * @param prefix
061     *            the prefix used for all names
062     * @param <K>
063     *            the map key type
064     * @param <V>
065     *            the map value type
066     * @return the clone of the source map
067     */
068    public static <K, V> Map<String, V> prefix(final Map<K, V> source, final String prefix) {
069
070        if (source == null) {
071            return null;
072        }
073
074        final Map<String, V> result = new HashMap<String, V>();
075
076        for (final Map.Entry<K, V> entry : source.entrySet()) {
077            final K key = entry.getKey();
078            final V value = entry.getValue();
079            result.put(prefix + '.' + key.toString(), value);
080        }
081
082        return result;
083    }
084
085    /**
086     * Clones the lhs map and add all things from the rhs map.
087     *
088     * @param lhs
089     *            the first map
090     * @param rhs
091     *            the second map
092     * @param <K>
093     *            the map key type
094     * @param <V>
095     *            the map value type
096     * @return the merged map
097     */
098    public static <K, V> Map<K, V> merge(final Map<K, V> lhs, final Map<K, V> rhs) {
099
100        Map<K, V> result = null;
101
102        if (lhs == null || lhs.size() == 0) {
103            result = copy(rhs);
104        }
105        else if (rhs == null || rhs.size() == 0) {
106            result = copy(lhs);
107        }
108        else {
109            result = copy(lhs);
110            result.putAll(rhs);
111        }
112        
113        return result;
114    }
115}