functionismatchpart.java

High performance DB query

/*
 * @(#)$Id: FunctionIsmatchpart.java,v 1.1 2004/12/17 20:15:09 huebsch Exp $
 *
 * Copyright (c) 2001-2004 Regents of the University of California.
 * All rights reserved.
 *
 * This file is distributed under the terms in the attached BERKELEY-LICENSE
 * file. If you do not find these files, copies can be found by writing to:
 * Computer Science Division, Database Group, Universite of California,
 * 617 Soda Hall #1776, Berkeley, CA 94720-1776. Attention: Berkeley License
 *
 * Copyright (c) 2003-2004 Intel Corporation. All rights reserved.
 *
 * This file is distributed under the terms in the attached INTEL-LICENSE file.
 * If you do not find these files, copies can be found by writing to:
 * Intel Research Berkeley, 2150 Shattuck Avenue, Suite 1300,
 * Berkeley, CA, 94704.  Attention:  Intel License Inquiry.
 */


package pier.helpers.functions;

import java.util.Collection;
import java.util.Iterator;
import java.util.StringTokenizer;
import java.util.TreeSet;

/**
 * Class FunctionConcat
 *
 */
public class FunctionIsmatchpart implements Function {

    /**
     * Method evaluate
     *
     * @param parameters
     * @return
     */
    public Object evaluate(Object[] parameters) {
        int params = parameters.length;

        if ((params == 3) || (params == 4)) {
            String delim1 = parameters[2].toString();
            String delim2 = (params == 4)
                            ? delim2 = parameters[3].toString()
                            : delim1;
            TreeSet set1 = (TreeSet) getParts(new TreeSet(),
                                              parameters[0].toString(), delim1);
            TreeSet set2 = (TreeSet) getParts(new TreeSet(),
                                              parameters[1].toString(), delim2);

            return new Boolean(haveMatch(set1, set2));
        } else {
            return null;
        }
    }

    /**
     * Method getParts
     *
     *
     * @param parts
     * @param string
     * @param delim
     * @return
     */
    protected Collection getParts(Collection parts, String string, String delim) {
        StringTokenizer strTokenizer = new StringTokenizer(string, delim);
        int count = strTokenizer.countTokens();

        for (int i = 0; i < count; i++) {
            parts.add(strTokenizer.nextToken());
        }

        return parts;
    }

    /**
     * Method haveMatch
     *
     * @param set1
     * @param set2
     * @return
     */
    protected boolean haveMatch(Collection set1, Collection set2) {
        Iterator iterator1 = set1.iterator();
        Iterator iterator2 = set2.iterator();

        if ((iterator1.hasNext() == false) || (iterator2.hasNext() == false)) {
            return false;
        }

        String head1 = (String) iterator1.next();
        String head2 = (String) iterator2.next();

        while (true) {
            int compareResult = head1.compareTo(head2);

            if (compareResult == 0) {
                return true;
            }

            if (compareResult < 0) {
                if (iterator1.hasNext()) {
                    head1 = (String) iterator1.next();
                } else {
                    return false;
                }
            } else {
                if (iterator2.hasNext()) {
                    head2 = (String) iterator2.next();
                } else {
                    return false;
                }
            }
        }
    }

    /**
     * Method cacheable
     * @return
     */
    public boolean cacheable() {
        return true;
    }
}