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