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