    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one
    003 * or more contributor license agreements.  See the NOTICE file
    004 * distributed with this work for additional information
    005 * regarding copyright ownership.  The ASF licenses this file
    006 * to you under the Apache License, Version 2.0 (the
    007 * "License"); you may not use this file except in compliance
    008 * with the License.  You may obtain a copy of the License at
    009 *
    010 *   https://www.apache.org/licenses/LICENSE-2.0
    011 *
    012 * Unless required by applicable law or agreed to in writing,
    013 * software distributed under the License is distributed on an
    014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    015 * KIND, either express or implied.  See the License for the
    016 * specific language governing permissions and limitations
    017 * under the License.
    018 */
    019
    020package org.apache.commons.exec.util;
    021
    022import java.util.HashMap;
    023import java.util.Map;
    024import java.util.Objects;
    025
    026/**
    027 * Helper classes to manipulate maps to pass substitution map to the CommandLine. This class is not part of the public API and could change without warning.
    028 */
    029public class MapUtils {
    030    /**
    031     * Clones a map.
    032     *
    033     * @param source the Map to clone.
    034     * @param <K>    the map key type.
    035     * @param <V>    the map value type.
    036     * @return the cloned map.
    037     */
    038    public static <K, V> Map<K, V> copy(final Map<K, V> source) {
    039        return source == null ? null : new HashMap<>(source);
    040    }
    041
    042    /**
    043     * Clones the lhs map and add all things from the rhs map.
    044     *
    045     * @param lhs the first map.
    046     * @param rhs the second map.
    047     * @param <K> the map key type.
    048     * @param <V> the map value type.
    049     * @return the merged map.
    050     */
    051    public static <K, V> Map<K, V> merge(final Map<K, V> lhs, final Map<K, V> rhs) {
    052        Map<K, V> result = null;
    053        if (lhs == null || lhs.isEmpty()) {
    054            result = copy(rhs);
    055        } else if (rhs == null || rhs.isEmpty()) {
    056            result = copy(lhs);
    057        } else {
    058            result = copy(lhs);
    059            result.putAll(rhs);
    060        }
    061        return result;
    062    }
    063
    064    /**
    065     * 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.
    066     *
    067     * @param source the source map.
    068     * @param prefix the prefix used for all names.
    069     * @param <K>    the map key type.
    070     * @param <V>    the map value type.
    071     * @return the clone of the source map.
    072     */
    073    public static <K, V> Map<String, V> prefix(final Map<K, V> source, final String prefix) {
    074        if (source == null) {
    075            return null;
    076        }
    077        final Map<String, V> result = new HashMap<>();
    078        for (final Map.Entry<K, V> entry : source.entrySet()) {
    079            result.put(prefix + '.' + Objects.toString(entry.getKey(), ""), entry.getValue());
    080        }
    081        return result;
    082    }
    083
    084    /**
    085     * Constructs a new instance.
    086     *
    087     * @deprecated Will be private in the next major version.
    088     */
    089    @Deprecated
    090    public MapUtils() {
    091        // empty
    092    }
    093}