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.iterators;
018
019import org.apache.commons.collections4.OrderedMapIterator;
020import org.apache.commons.collections4.Unmodifiable;
021
022/**
023 * Decorates an ordered map iterator such that it cannot be modified.
024 * <p>
025 * Attempts to modify it will result in an UnsupportedOperationException.
026 *
027 * @since 3.0
028 */
029public final class UnmodifiableOrderedMapIterator<K, V> implements OrderedMapIterator<K, V>,
030        Unmodifiable {
031
032    /** The iterator being decorated */
033    private final OrderedMapIterator<? extends K, ? extends V> iterator;
034
035    //-----------------------------------------------------------------------
036    /**
037     * Decorates the specified iterator such that it cannot be modified.
038     *
039     * @param <K>  the key type
040     * @param <V>  the value type
041     * @param iterator  the iterator to decorate
042     * @return a new unmodifiable ordered map iterator
043     * @throws NullPointerException if the iterator is null
044     */
045    public static <K, V> OrderedMapIterator<K, V> unmodifiableOrderedMapIterator(
046            final OrderedMapIterator<K, ? extends V> iterator) {
047
048        if (iterator == null) {
049            throw new NullPointerException("OrderedMapIterator must not be null");
050        }
051        if (iterator instanceof Unmodifiable) {
052            @SuppressWarnings("unchecked") // safe to upcast
053            final OrderedMapIterator<K, V> tmpIterator = (OrderedMapIterator<K, V>) iterator;
054            return tmpIterator;
055        }
056        return new UnmodifiableOrderedMapIterator<>(iterator);
057    }
058
059    //-----------------------------------------------------------------------
060    /**
061     * Constructor.
062     *
063     * @param iterator  the iterator to decorate
064     */
065    private UnmodifiableOrderedMapIterator(final OrderedMapIterator<K, ? extends V> iterator) {
066        super();
067        this.iterator = iterator;
068    }
069
070    //-----------------------------------------------------------------------
071    @Override
072    public boolean hasNext() {
073        return iterator.hasNext();
074    }
075
076    @Override
077    public K next() {
078        return iterator.next();
079    }
080
081    @Override
082    public boolean hasPrevious() {
083        return iterator.hasPrevious();
084    }
085
086    @Override
087    public K previous() {
088        return iterator.previous();
089    }
090
091    @Override
092    public K getKey() {
093        return iterator.getKey();
094    }
095
096    @Override
097    public V getValue() {
098        return iterator.getValue();
099    }
100
101    @Override
102    public V setValue(final V value) {
103        throw new UnsupportedOperationException("setValue() is not supported");
104    }
105
106    @Override
107    public void remove() {
108        throw new UnsupportedOperationException("remove() is not supported");
109    }
110
111}