Spliterator.java

/*
 * Copyright (C) 2010 eXo Platform SAS.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */

package org.exoplatform.commons.utils;

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


/**
 * An iterator that splits a string into chunks without requiring to allocate an array to hold the various chunks of the
 * splitted string.
 *
 * @author <a href="mailto:julien.viet@exoplatform.com">Julien Viet</a>
 * @version $Revision$
 */
public class Spliterator implements Iterator<String> {

    /** . */
    private final String s;

    /** . */
    private final char separator;

    /** . */
    private int from;

    /** . */
    private Integer to;

    /**
     * Creates a spliterator.
     *
     * @param s the string to split
     * @param separator the separator
     * @throws NullPointerException if the string is null
     */
    public Spliterator(String s, char separator) throws NullPointerException {
        if (s == null) {
            throw new NullPointerException();
        }

        //
        this.s = s;
        this.separator = separator;
        this.from = 0;
        this.to = null;
    }

    public boolean hasNext() {
        if (from == -1) {
            return false;
        } else {
            if (to == null) {
                to = s.indexOf(separator, from);
            }
            return true;
        }
    }

    public String next() {
        if (hasNext()) {
            String next;
            if (to == -1) {
                next = s.substring(from);
                from = -1;
            } else {
                next = s.substring(from, to);
                from = to + 1;
            }
            to = null;
            return next;
        } else {
            throw new NoSuchElementException();
        }
    }

    public void remove() {
        throw new UnsupportedOperationException();
    }
}