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.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     * Constructor only used in deserialization, do not use otherwise.
053     * @since 3.1
054     */
055    protected AbstractSortedMapDecorator() {
056        super();
057    }
058
059    /**
060     * Constructor that wraps (not copies).
061     *
062     * @param map  the map to decorate, must not be null
063     * @throws NullPointerException if the map is null
064     */
065    public AbstractSortedMapDecorator(final SortedMap<K, V> map) {
066        super(map);
067    }
068
069    /**
070     * Gets the map being decorated.
071     *
072     * @return the decorated map
073     */
074    @Override
075    protected SortedMap<K, V> decorated() {
076        return (SortedMap<K, V>) super.decorated();
077    }
078
079    //-----------------------------------------------------------------------
080    @Override
081    public Comparator<? super K> comparator() {
082        return decorated().comparator();
083    }
084
085    @Override
086    public K firstKey() {
087        return decorated().firstKey();
088    }
089
090    @Override
091    public K lastKey() {
092        return decorated().lastKey();
093    }
094
095    @Override
096    public SortedMap<K, V> subMap(final K fromKey, final K toKey) {
097        return decorated().subMap(fromKey, toKey);
098    }
099
100    @Override
101    public SortedMap<K, V> headMap(final K toKey) {
102        return decorated().headMap(toKey);
103    }
104
105    @Override
106    public SortedMap<K, V> tailMap(final K fromKey) {
107        return decorated().tailMap(fromKey);
108    }
109
110    @Override
111    public K previousKey(final K key) {
112        final SortedMap<K, V> headMap = headMap(key);
113        return headMap.isEmpty() ? null : headMap.lastKey();
114    }
115
116    @Override
117    public K nextKey(final K key) {
118        final Iterator<K> it = tailMap(key).keySet().iterator();
119        it.next();
120        return it.hasNext() ? it.next() : null;
121    }
122
123    /**
124     * {@inheritDoc}
125     */
126    @Override
127    public OrderedMapIterator<K, V> mapIterator() {
128        return new SortedMapIterator<>(entrySet());
129    }
130
131    /**
132     * OrderedMapIterator implementation.
133     *
134     * @param <K>  the key type
135     * @param <V>  the value type
136     */
137    protected static class SortedMapIterator<K, V> extends EntrySetToMapIteratorAdapter<K, V>
138            implements OrderedMapIterator<K, V> {
139
140        /**
141         * Create a new AbstractSortedMapDecorator.SortedMapIterator.
142         * @param entrySet  the entrySet to iterate
143         */
144        protected SortedMapIterator(final Set<Map.Entry<K, V>> entrySet) {
145            super(entrySet);
146        }
147
148        /**
149         * {@inheritDoc}
150         */
151        @Override
152        public synchronized void reset() {
153            super.reset();
154            iterator = new ListIteratorWrapper<>(iterator);
155        }
156
157        /**
158         * {@inheritDoc}
159         */
160        @Override
161        public boolean hasPrevious() {
162            return ((ListIterator<Map.Entry<K, V>>) iterator).hasPrevious();
163        }
164
165        /**
166         * {@inheritDoc}
167         */
168        @Override
169        public K previous() {
170            entry = ((ListIterator<Map.Entry<K, V>>) iterator).previous();
171            return getKey();
172        }
173    }
174}