    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}