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The TwelveMonkeys Core library. Contains common utility classes.
There is a newer version: 2.3
/*
 * Copyright (c) 2008, Harald Kuhr
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name "TwelveMonkeys" nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package com.twelvemonkeys.util.regex;

import com.twelvemonkeys.util.AbstractTokenIterator;

import java.util.NoSuchElementException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.regex.PatternSyntaxException;

/**
 * {@code StringTokenizer} replacement, that uses regular expressions to split
 * strings into tokens.
 * 
 * @see java.util.regex.Pattern for pattern syntax.
 *
 * @author Harald Kuhr
 * @version $Id: //depot/branches/personal/haraldk/twelvemonkeys/release-2/twelvemonkeys-core/src/main/java/com/twelvemonkeys/util/regex/RegExTokenIterator.java#1 $
 */
public class RegExTokenIterator extends AbstractTokenIterator {
    private final Matcher mMatcher;
    private boolean mNext = false;

    /**
     * Creates a {@code RegExTokenIterator}.
     * Default pettern is {@code "\S+"}.
     *
     * @param pString the string to be parsed.
     *
     * @throws IllegalArgumentException if {@code pString} is {@code null}
     */
    public RegExTokenIterator(String pString) {
        this(pString, "\\S+");
    }

    /**
     * Creates a {@code RegExTokenIterator}.
     *
     * @see Pattern for pattern syntax.
     *
     * @param pString the string to be parsed.
     * @param pPattern the pattern
     *
     * @throws PatternSyntaxException if {@code pPattern} is not a valid pattern
     * @throws IllegalArgumentException if any of the arguments are {@code null}
     */
    public RegExTokenIterator(String pString, String pPattern) {
        if (pString == null) {
            throw new IllegalArgumentException("string == null");
        }

        if (pPattern == null) {
            throw new IllegalArgumentException("pattern == null");
        }

        mMatcher = Pattern.compile(pPattern).matcher(pString);
    }

    /**
     * Resets this iterator.
     *
     */
    public void reset() {
        mMatcher.reset();
    }

    public boolean hasNext() {
        return mNext || (mNext = mMatcher.find());
    }

    public String next() {
        if (!hasNext()) {
            throw new NoSuchElementException();
        }
        mNext = false;
        return mMatcher.group();
    }
}