    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}