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.Collections;
024import java.util.HashMap;
025import java.util.HashSet;
026import java.util.Iterator;
027import java.util.LinkedHashMap;
028import java.util.List;
029import java.util.Map;
030import java.util.Properties;
031import java.util.Set;
032import java.util.function.Supplier;
033
034import org.w3c.dom.NodeList;
035
036/**
037 * A number of helper methods for working with collections
038 */
039public final class CollectionHelper {
040
041    /**
042     * Utility classes should not have a public constructor.
043     */
044    private CollectionHelper() {
045    }
046
047    /**
048     * Returns the size of the collection if it can be determined to be a collection
049     *
050     * @param value the collection
051     * @return the size, or <tt>null</tt> if not a collection
052     */
053    public static Integer size(Object value) {
054        if (value != null) {
055            if (value instanceof Collection) {
056                Collection<?> collection = (Collection<?>) value;
057                return collection.size();
058            } else if (value instanceof Map) {
059                Map<?, ?> map = (Map<?, ?>) value;
060                return map.size();
061            } else if (value instanceof Object[]) {
062                Object[] array = (Object[]) value;
063                return array.length;
064            } else if (value.getClass().isArray()) {
065                return Array.getLength(value);
066            } else if (value instanceof NodeList) {
067                NodeList nodeList = (NodeList) value;
068                return nodeList.getLength();
069            }
070        }
071        return null;
072    }
073
074    /**
075     * Sets the value of the entry in the map for the given key, though if the
076     * map already contains a value for the given key then the value is appended
077     * to a list of values.
078     *
079     * @param map the map to add the entry to
080     * @param key the key in the map
081     * @param value the value to put in the map
082     */
083    @SuppressWarnings("unchecked")
084    public static void appendValue(Map<String, Object> map, String key, Object value) {
085        Object oldValue = map.get(key);
086        if (oldValue != null) {
087            List<Object> list;
088            if (oldValue instanceof List) {
089                list = (List<Object>) oldValue;
090            } else {
091                list = new ArrayList<>();
092                list.add(oldValue);
093                // replace old entry with list
094                map.remove(key);
095                map.put(key, list);
096            }
097            list.add(value);
098        } else {
099            map.put(key, value);
100        }
101    }
102
103    public static <T> Set<T> createSetContaining(T... contents) {
104        return new HashSet<>(Arrays.asList(contents));
105    }
106
107    public static String collectionAsCommaDelimitedString(Collection<?> col) {
108        if (col == null || col.isEmpty()) {
109            return "";
110        }
111
112        StringBuilder sb = new StringBuilder();
113        Iterator<?> it = col.iterator();
114        while (it.hasNext()) {
115            sb.append(it.next().toString());
116            if (it.hasNext()) {
117                sb.append(",");
118            }
119        }
120
121        return sb.toString();
122    }
123
124    /**
125     * Traverses the given map recursively and flattern the keys by combining them with the optional separator.
126     *
127     * @param map  the map
128     * @param separator optional separator to use in key name, for example a hyphen or dot.
129     * @return the map with flattern keys
130     */
131    public static Map<String, Object> flattenKeysInMap(Map<String, Object> map, String separator) {
132        Map<String, Object> answer = new LinkedHashMap<>();
133        doFlattenKeysInMap(map, "", ObjectHelper.isNotEmpty(separator) ? separator : "", answer);
134        return answer;
135    }
136
137    private static void doFlattenKeysInMap(Map<String, Object> source, String prefix, String separator, Map<String, Object> target) {
138        for (Map.Entry<String, Object> entry : source.entrySet()) {
139            String key = entry.getKey();
140            Object value = entry.getValue();
141            String newKey = prefix.isEmpty() ? key : prefix + separator + key;
142
143            if (value instanceof Map) {
144                Map map = (Map) value;
145                doFlattenKeysInMap(map, newKey, separator, target);
146            } else {
147                target.put(newKey, value);
148            }
149        }
150    }
151
152    /**
153     * Build an unmodifiable map on top of a given map. Note tha thew given map is
154     * copied if not null.
155     *
156     * @param map a map
157     * @return an unmodifiable map.
158     */
159    public static <K, V> Map<K, V> unmodifiableMap(Map<K, V> map) {
160        return map == null
161            ? Collections.emptyMap()
162            : Collections.unmodifiableMap(new HashMap<>(map));
163    }
164
165
166    /**
167     * Build a map from varargs.
168     */
169    public static <K, V> Map<K, V> mapOf(Supplier<Map<K, V>> creator, K key, V value, Object... keyVals) {
170        Map<K, V> map = creator.get();
171        map.put(key, value);
172
173        for (int i = 0; i < keyVals.length; i += 2) {
174            map.put(
175                (K) keyVals[i],
176                (V) keyVals[i + 1]
177            );
178        }
179
180        return map;
181    }
182
183
184    /**
185     * Build an immutable map from varargs.
186     */
187    public static <K, V> Map<K, V> immutableMapOf(Supplier<Map<K, V>> creator, K key, V value, Object... keyVals) {
188        return Collections.unmodifiableMap(
189            mapOf(creator, key, value, keyVals)
190        );
191    }
192
193    /**
194     * Build a map from varargs.
195     */
196    public static <K, V> Map<K, V> mapOf(K key, V value, Object... keyVals) {
197        return mapOf(HashMap::new, key, value, keyVals);
198    }
199
200    /**
201     * Build an immutable map from varargs.
202     */
203    public static <K, V> Map<K, V> immutableMapOf(K key, V value, Object... keyVals) {
204        return Collections.unmodifiableMap(
205            mapOf(HashMap::new, key, value, keyVals)
206        );
207    }
208
209    /**
210     * Build a {@link java.util.Properties} from varargs.
211     */
212    public static Properties propertiesOf(String key, String value, String... keyVals) {
213        Properties properties = new Properties();
214        properties.setProperty(key, value);
215
216        for (int i = 0; i < keyVals.length; i += 2) {
217            properties.setProperty(
218                keyVals[i],
219                keyVals[i + 1]
220            );
221        }
222
223        return properties;
224    }
225}