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