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.camel.util;
018
019import java.lang.reflect.Array;
020import java.util.ArrayList;
021import java.util.Arrays;
022import java.util.Collection;
023import java.util.HashSet;
024import java.util.Iterator;
025import java.util.LinkedHashMap;
026import java.util.List;
027import java.util.Map;
028import java.util.Set;
029
030import org.w3c.dom.NodeList;
031
032/**
033 * A number of helper methods for working with collections
034 *
035 * @version
036 */
037public final class CollectionHelper {
038
039    /**
040     * Utility classes should not have a public constructor.
041     */
042    private CollectionHelper() {
043    }
044
045    /**
046     * Returns the size of the collection if it can be determined to be a collection
047     *
048     * @param value the collection
049     * @return the size, or <tt>null</tt> if not a collection
050     */
051    public static Integer size(Object value) {
052        if (value != null) {
053            if (value instanceof Collection) {
054                Collection<?> collection = (Collection<?>) value;
055                return collection.size();
056            } else if (value instanceof Map) {
057                Map<?, ?> map = (Map<?, ?>) value;
058                return map.size();
059            } else if (value instanceof Object[]) {
060                Object[] array = (Object[]) value;
061                return array.length;
062            } else if (value.getClass().isArray()) {
063                return Array.getLength(value);
064            } else if (value instanceof NodeList) {
065                NodeList nodeList = (NodeList) value;
066                return nodeList.getLength();
067            }
068        }
069        return null;
070    }
071
072    /**
073     * Sets the value of the entry in the map for the given key, though if the
074     * map already contains a value for the given key then the value is appended
075     * to a list of values.
076     *
077     * @param map the map to add the entry to
078     * @param key the key in the map
079     * @param value the value to put in the map
080     */
081    @SuppressWarnings("unchecked")
082    public static void appendValue(Map<String, Object> map, String key, Object value) {
083        Object oldValue = map.get(key);
084        if (oldValue != null) {
085            List<Object> list;
086            if (oldValue instanceof List) {
087                list = (List<Object>) oldValue;
088            } else {
089                list = new ArrayList<Object>();
090                list.add(oldValue);
091                // replace old entry with list
092                map.remove(key);
093                map.put(key, list);
094            }
095            list.add(value);
096        } else {
097            map.put(key, value);
098        }
099    }
100
101    public static <T> Set<T> createSetContaining(T... contents) {
102        Set<T> contentsAsSet = new HashSet<T>();
103        contentsAsSet.addAll(Arrays.asList(contents));
104        return contentsAsSet;
105    }
106
107    public static String collectionAsCommaDelimitedString(String[] col) {
108        if (col == null || col.length == 0) {
109            return "";
110        }
111        return collectionAsCommaDelimitedString(Arrays.asList(col));
112    }
113
114    public static String collectionAsCommaDelimitedString(Collection<?> col) {
115        if (col == null || col.isEmpty()) {
116            return "";
117        }
118
119        StringBuilder sb = new StringBuilder();
120        Iterator<?> it = col.iterator();
121        while (it.hasNext()) {
122            sb.append(it.next().toString());
123            if (it.hasNext()) {
124                sb.append(",");
125            }
126        }
127
128        return sb.toString();
129    }
130
131    /**
132     * Traverses the given map recursively and flattern the keys by combining them with the optional separator.
133     *
134     * @param map  the map
135     * @param separator optional separator to use in key name, for example a hyphen or dot.
136     * @return the map with flattern keys
137     */
138    public static Map<String, Object> flatternKeysInMap(Map<String, Object> map, String separator) {
139        Map<String, Object> answer = new LinkedHashMap<>();
140        doFlatternKeysInMap(map, "", ObjectHelper.isNotEmpty(separator) ? separator : "", answer);
141        return answer;
142    }
143
144    private static void doFlatternKeysInMap(Map<String, Object> source, String prefix, String separator, Map<String, Object> target) {
145        for (Map.Entry<String, Object> entry : source.entrySet()) {
146            String key = entry.getKey();
147            Object value = entry.getValue();
148            String newKey = prefix.isEmpty() ? key : prefix + separator + key;
149
150            if (value instanceof Map) {
151                Map map = (Map) value;
152                doFlatternKeysInMap(map, newKey, separator, target);
153            } else {
154                target.put(newKey, value);
155            }
156        }
157    }
158}