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 *      https://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.commons.collections4.map;
018
019import java.util.Comparator;
020import java.util.Iterator;
021import java.util.ListIterator;
022import java.util.Map;
023import java.util.Set;
024import java.util.SortedMap;
025
026import org.apache.commons.collections4.IterableSortedMap;
027import org.apache.commons.collections4.OrderedMapIterator;
028import org.apache.commons.collections4.iterators.ListIteratorWrapper;
029
030/**
031 * Provides a base decorator that enables additional functionality to be added
032 * to a Map via decoration.
033 * <p>
034 * Methods are forwarded directly to the decorated map.
035 * </p>
036 * <p>
037 * This implementation does not perform any special processing with the map views.
038 * Instead it simply returns the set/collection from the wrapped map. This may be
039 * undesirable, for example if you are trying to write a validating implementation
040 * it would provide a loophole around the validation.
041 * But, you might want that loophole, so this class is kept simple.
042 * </p>
043 *
044 * @param <K> The type of the keys in the map
045 * @param <V> The type of the values in the map
046 * @since 3.0
047 */
048public abstract class AbstractSortedMapDecorator<K, V> extends AbstractMapDecorator<K, V> implements
049        IterableSortedMap<K, V> {
050
051    /**
052     * OrderedMapIterator implementation.
053     *
054     * @param <K>  the key type
055     * @param <V>  the value type
056     */
057    protected static class SortedMapIterator<K, V> extends EntrySetToMapIteratorAdapter<K, V>
058            implements OrderedMapIterator<K, V> {
059
060        /**
061         * Create a new AbstractSortedMapDecorator.SortedMapIterator.
062         *
063         * @param entrySet  The entrySet to iterate
064         */
065        protected SortedMapIterator(final Set<Map.Entry<K, V>> entrySet) {
066            super(entrySet);
067        }
068
069        /**
070         * {@inheritDoc}
071         */
072        @Override
073        public boolean hasPrevious() {
074            return ((ListIterator<Map.Entry<K, V>>) iterator).hasPrevious();
075        }
076
077        /**
078         * {@inheritDoc}
079         */
080        @Override
081        public K previous() {
082            entry = ((ListIterator<Map.Entry<K, V>>) iterator).previous();
083            return getKey();
084        }
085
086        /**
087         * {@inheritDoc}
088         */
089        @Override
090        public synchronized void reset() {
091            super.reset();
092            iterator = new ListIteratorWrapper<>(iterator);
093        }
094    }
095
096    /**
097     * Constructor only used in deserialization, do not use otherwise.
098     *
099     * @since 3.1
100     */
101    protected AbstractSortedMapDecorator() {
102    }
103
104    /**
105     * Constructor that wraps (not copies).
106     *
107     * @param map  The map to decorate, must not be null
108     * @throws NullPointerException if the map is null
109     */
110    public AbstractSortedMapDecorator(final SortedMap<K, V> map) {
111        super(map);
112    }
113
114    @Override
115    public Comparator<? super K> comparator() {
116        return decorated().comparator();
117    }
118
119    /**
120     * Gets the map being decorated.
121     *
122     * @return The decorated map
123     */
124    @Override
125    protected SortedMap<K, V> decorated() {
126        return (SortedMap<K, V>) super.decorated();
127    }
128
129    @Override
130    public K firstKey() {
131        return decorated().firstKey();
132    }
133
134    @Override
135    public SortedMap<K, V> headMap(final K toKey) {
136        return decorated().headMap(toKey);
137    }
138
139    @Override
140    public K lastKey() {
141        return decorated().lastKey();
142    }
143
144    /**
145     * {@inheritDoc}
146     */
147    @Override
148    public OrderedMapIterator<K, V> mapIterator() {
149        return new SortedMapIterator<>(entrySet());
150    }
151
152    @Override
153    public K nextKey(final K key) {
154        final Iterator<K> it = tailMap(key).keySet().iterator();
155        it.next();
156        return it.hasNext() ? it.next() : null;
157    }
158
159    @Override
160    public K previousKey(final K key) {
161        final SortedMap<K, V> headMap = headMap(key);
162        return headMap.isEmpty() ? null : headMap.lastKey();
163    }
164
165    @Override
166    public SortedMap<K, V> subMap(final K fromKey, final K toKey) {
167        return decorated().subMap(fromKey, toKey);
168    }
169
170    @Override
171    public SortedMap<K, V> tailMap(final K fromKey) {
172        return decorated().tailMap(fromKey);
173    }
174}