com.sun.electric.util.collections.ArrayIterator Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of electric-utils Show documentation
Electric utils.
The newest version!
/* -*- tab-width: 4 -*-
 *
 * Electric(tm) VLSI Design System
 *
 * File: ArrayIterarator.java
 * Written by: Dmitry Nadezhin, Sun Microsystems.
 *
 * Copyright (c) 2003, Oracle and/or its affiliates. All rights reserved.
 *
 * Electric(tm) is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * Electric(tm) is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Electric(tm); see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
 * Boston, Mass 02111-1307, USA.
 */
package com.sun.electric.util.collections;

import java.util.Iterator;
import java.util.ArrayList;
import java.util.NoSuchElementException;

/**
 * An iterator over an array.
 */
public class ArrayIterator implements Iterator {

    private final E[] array;
    private final int limit;
    private int cursor;

    private ArrayIterator(E[] array) {
        this.array = array;
        limit = array.length;
        cursor = 0;
    }

    private ArrayIterator(E[] array, int start, int limit) {
        this.array = array;
        this.limit = limit;
        cursor = start;
    }

    /**
     * Returns iterator over elements of array.
     * @param array array with elements or null.
     * @return iterator over elements of the array or NULL_ITERATOR.
     */
    public static  Iterator iterator(E[] array) {
        if (array != null && array.length > 0) {
            return new ArrayIterator(array);
        }
        Iterator emptyIterator = emptyIterator();
        return emptyIterator;
    }

    /**
     * Returns iterator over range [start,limit) of elements of array.
     * @param array array with elements or null.
     * @param start start index of the range.
     * @param limit limit of the range
     * @return iterator over range of elements of the array or EMPTY_ITERATOR.
     * @throws IndexOutOfBoundsException if start or limit are not correct
     */
    public static  Iterator iterator(E[] array, int start, int limit) {
        if (array != null) {
            if (start >= 0 && limit <= array.length) {
                if (start < limit) {
                    return new ArrayIterator(array, start, limit);
                } else if (start == limit) {
                    Iterator emptyIterator = emptyIterator();
                    return emptyIterator;
                }
            }
        } else if (start == 0 && limit == 0) {
            Iterator emptyIterator = emptyIterator();
            return emptyIterator;
        }
        throw new IndexOutOfBoundsException();
    }

    /**
     * Returns true if the iteration has more elements. (In other
     * words, returns true if next would return an element
     * rather than throwing an exception.)
     *
     * @return true if the iterator has more elements.
     */
    public boolean hasNext() {
        return cursor < limit;
    }

    /**
     * Returns the next element in the iteration.  Calling this method
     * repeatedly until the {@link #hasNext()} method returns false will
     * return each element in the underlying collection exactly once.
     *
     * @return the next element in the iteration.
     * @exception NoSuchElementException iteration has no more elements.
     */
    public E next() {
        if (cursor >= limit) {
            throw new NoSuchElementException();
        }
        E next = array[cursor];
        cursor++;
        return next;
    }

    /**
     * Removes from the underlying collection the last element returned by the
     * iterator (unsupported operation).
     *
     * @exception UnsupportedOperationException
     */
    public void remove() {
        throw new UnsupportedOperationException();
    }

    /**
     * Null iterator which has no elements.
     */
    private static class EmptyIterator extends ArrayIterator