ArrayIterator.java

/*
* Copyright 2016 Nabarun Mondal
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/


package com.noga.njexl.lang.internal;

import java.util.Iterator;
import java.util.NoSuchElementException;
import java.lang.reflect.Array;

/**
 *  <p>
 *  An Iterator wrapper for an Object[]. This will
 *  allow us to deal with all array like structures
 *  in a consistent manner.
 *  </p>
 *  <p>
 *  WARNING : this class's operations are NOT synchronized.
 *  It is meant to be used in a single thread, newly created
 *  for each use in the #foreach() directive.
 *  If this is used or shared, synchronize in the
 *  next() method.
 *  </p>
 *
 * @since 1.0
 */
public class ArrayIterator implements Iterator<Object> {
    /** The objects to iterate over. */
    private final Object array;
    /** The size of the array. */
    private final int size;
    /** The current position and size in the array. */
    private int pos;

    /**
     * Creates a new iterator instance for the specified array.
     * @param arr The array for which an iterator is desired.
     */
    public ArrayIterator(Object arr) {
        if (!arr.getClass().isArray()) {
            throw new IllegalArgumentException(arr.getClass() + " is not an array");
        }
        array = arr;
        pos = 0;
        size = Array.getLength(array);
    }

    /**
     * Move to next element in the array.
     * Checks are removed, because clearly none should call next() w/o a hasNext()
     * @return The next object in the array.
     */
    public Object next() {
        return Array.get(array, pos++);
    }
    
    /**
     * Check to see if there is another element in the array.
     *
     * @return Whether there is another element.
     */
    public boolean hasNext() {
        return (pos < size);
    }

    /**
     * No op--merely added to satify the <code>Iterator</code> interface.
     * Hence, exceptions are removed, this is a NOP.
     */
    public void remove() {}
}