3514 - Script Levenstein

DELIMITER $$
CREATE DEFINER=`calcium`@`` FUNCTION `levenshtein`(s1 varchar(255), s2 varchar(255)) RETURNS int(11)
   DETERMINISTIC
BEGIN
 DECLARE s1_len,
          s2_len,
          i,
          j,
         c,
          c_temp,
          cost int;
 DECLARE s1_char char;
 -- max strlen=255
 DECLARE cv0,
          cv1 varbinary(256);
 SET s1_len = CHAR_LENGTH(s1), s2_len = CHAR_LENGTH(s2), cv1 = 0x00, j = 1, i = 1, c = 0;
 IF s1 = s2 THEN
   RETURN 0;
  ELSEIF s1_len = 0 THEN
   RETURN s2_len;
  ELSEIF s2_len = 0 THEN
   RETURN s1_len;
 ELSE
    WHILE j <= s2_len DO
     SET cv1 = CONCAT(cv1, UNHEX(HEX(j))), j = j + 1;
   END WHILE;
    WHILE i <= s1_len DO
     SET s1_char = SUBSTRING(s1, i, 1), c = i, cv0 = UNHEX(HEX(i)), j = 1;
      WHILE j <= s2_len DO
       SET c = c + 1;
       IF s1_char = SUBSTRING(s2, j, 1) THEN
         SET cost = 0;
       ELSE
         SET cost = 1;
       END IF;
       SET c_temp = CONV(HEX(SUBSTRING(cv1, j, 1)), 16, 10) + cost;
       IF c > c_temp THEN
         SET c = c_temp;
       END IF;
       SET c_temp = CONV(HEX(SUBSTRING(cv1, j + 1, 1)), 16, 10) + 1;
       IF c > c_temp THEN
         SET c = c_temp;
       END IF;
       SET cv0 = CONCAT(cv0, UNHEX(HEX(c))), j = j + 1;
     END WHILE;
     SET cv1 = cv0, i = i + 1;
   END WHILE;
 END IF;
 RETURN c;
END$$

DELIMITER ;