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 */
017
018package org.apache.commons.jexl3.internal.introspection;
019
020import java.lang.reflect.Array;
021import java.util.Iterator;
022import java.util.NoSuchElementException;
023
024/**
025 *  <p>
026 *  An Iterator wrapper for an Object[]. This will
027 *  allow us to deal with all array like structures
028 *  in a consistent manner.
029 *  </p>
030 *  <p>
031 *  WARNING : this class's operations are NOT synchronized.
032 *  It is meant to be used in a single thread, newly created
033 *  for each use in the #foreach() directive.
034 *  If this is used or shared, synchronize in the
035 *  next() method.
036 *  </p>
037 *
038 * @since 1.0
039 */
040public class ArrayIterator implements Iterator<Object> {
041    /** The objects to iterate over. */
042    private final Object array;
043    /** The size of the array. */
044    private final int size;
045    /** The current position and size in the array. */
046    private int pos;
047
048    /**
049     * Creates a new iterator instance for the specified array.
050     * @param arr The array for which an iterator is desired.
051     */
052    public ArrayIterator(final Object arr) {
053        if (arr == null) {
054            array = null;
055            pos = 0;
056            size = 0;
057        } else if (!arr.getClass().isArray()) {
058            throw new IllegalArgumentException(arr.getClass() + " is not an array");
059        } else {
060            array = arr;
061            pos = 0;
062            size = Array.getLength(array);
063        }
064    }
065
066    /**
067     * Move to next element in the array.
068     *
069     * @return The next object in the array.
070     */
071    @Override
072    public Object next() {
073        if (pos < size) {
074            return Array.get(array, pos++);
075        }
076        // we screwed up...
077        throw new NoSuchElementException("No more elements: " + pos
078                                         + " / " + size);
079    }
080
081    /**
082     * Check to see if there is another element in the array.
083     *
084     * @return Whether there is another element.
085     */
086    @Override
087    public boolean hasNext() {
088        return (pos < size);
089    }
090
091    /**
092     * No op--merely added to satify the <code>Iterator</code> interface.
093     */
094    @Override
095    public void remove() {
096        throw new UnsupportedOperationException();
097    }
098}