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
018package org.apache.commons.exec.util;
019
020import java.util.HashMap;
021import java.util.Map;
022import java.util.Objects;
023
024/**
025 * Helper classes to manipulate maps to pass substition map to the CommandLine. This class is not part of the public API and could change without warning.
026 */
027public class MapUtils {
028    /**
029     * Clones a map.
030     *
031     * @param source the Map to clone.
032     * @param <K>    the map key type.
033     * @param <V>    the map value type.
034     * @return the cloned map.
035     */
036    public static <K, V> Map<K, V> copy(final Map<K, V> source) {
037        return source == null ? null : new HashMap<>(source);
038    }
039
040    /**
041     * Clones the lhs map and add all things from the rhs map.
042     *
043     * @param lhs the first map.
044     * @param rhs the second map.
045     * @param <K> the map key type.
046     * @param <V> the map value type.
047     * @return the merged map.
048     */
049    public static <K, V> Map<K, V> merge(final Map<K, V> lhs, final Map<K, V> rhs) {
050        Map<K, V> result = null;
051        if (lhs == null || lhs.isEmpty()) {
052            result = copy(rhs);
053        } else if (rhs == null || rhs.isEmpty()) {
054            result = copy(lhs);
055        } else {
056            result = copy(lhs);
057            result.putAll(rhs);
058        }
059        return result;
060    }
061
062    /**
063     * Clones a map and prefixes the keys in the clone, e.g. for mapping "JAVA_HOME" to "env.JAVA_HOME" to simulate the behavior of Ant.
064     *
065     * @param source the source map.
066     * @param prefix the prefix used for all names.
067     * @param <K>    the map key type.
068     * @param <V>    the map value type.
069     * @return the clone of the source map.
070     */
071    public static <K, V> Map<String, V> prefix(final Map<K, V> source, final String prefix) {
072        if (source == null) {
073            return null;
074        }
075        final Map<String, V> result = new HashMap<>();
076        for (final Map.Entry<K, V> entry : source.entrySet()) {
077            result.put(prefix + '.' + Objects.toString(entry.getKey(), ""), entry.getValue());
078        }
079        return result;
080    }
081}