functionmatchbytes.java

High performance DB query

/*
 * @(#)$Id: FunctionMatchbytes.java,v 1.2 2005/03/08 02:17:09 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.ArrayList;
import java.util.Collection;

/**
 * Class FunctionConcat
 *
 */
public class FunctionMatchbytes extends FunctionMatchpart implements Function {

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

        if ((params == 3) || (params == 4)) {
            Byte[] bytes1 = (Byte[]) parameters[0];
            Byte[] bytes2 = (Byte[]) parameters[1];
            int setLength = ((Integer) parameters[2]).intValue();
            boolean toDistance = (params == 4)
                                 ? ((Boolean) parameters[3]).booleanValue()
                                 : true;

            if ((bytes1 == null) || (bytes2 == null)) {
                return new Integer(-1);
            }

            ArrayList set1 = (ArrayList) getParts(new ArrayList(), bytes1,
                                                  setLength);
            ArrayList set2 = (ArrayList) getParts(new ArrayList(), bytes2,
                                                  setLength);

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

    /**
     * Method getParts
     *
     * @param parts
     * @param bytes
     * @param setLength
     * @return
     */
    protected Collection getParts(Collection parts, Byte[] bytes,
                                  int setLength) {
        for (int start = 0; start < bytes.length; start += setLength) {
            parts.add(new ByteSet(bytes, start, setLength));
        }

        return parts;
    }

    /**
     * Class ByteSet
     *
     */
    public class ByteSet {

        private Byte[] bytes;
        private int start;
        private int length;

        /**
         * Constructor ByteSet
         *
         * @param bytes
         * @param start
         * @param length
         */
        public ByteSet(Byte[] bytes, int start, int length) {
            this.bytes = bytes;
            this.start = start;
            this.length = length;
        }

        /**
         * Method equals
         *
         * @param other
         * @return
         */
        public boolean equals(Object other) {
            if (other instanceof ByteSet) {
                ByteSet otherSet = (ByteSet) other;

                if (otherSet.length == length) {
                    for (int i = 0; i < length; i++) {
                        if ( !(bytes[start + i].equals(
                                otherSet.bytes[otherSet.start + i]))) {
                            return false;
                        }
                    }

                    return true;
                }

                return false;
            } else {
                throw new RuntimeException(
                    "Unsupported data type for comparing: " + this.getClass()
                    + " and " + other.getClass());
            }
        }
    }
}