    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}