StringBuffer buff = new StringBuffer(s.length());
        int start = 0;
        int len = replace.length();
        while (true) {
            int i = s.indexOf(replace, start);
            if (i == -1) {
                break;
            }
            buff.append(s.substring(start, i));
            buff.append(with);
            start = i + len;
        }
        buff.append(s.substring(start));
        return buff.toString();
    }

    private static String repeat(String s, int count) {
        StringBuffer buff = new StringBuffer(s.length() * count);
        while (count-- > 0) {
            buff.append(s);
        }
        return buff.toString();
    }

    private static String rawToHex(String s) {
        StringBuffer buff = new StringBuffer(4 * s.length());
        for (int i = 0; i < s.length(); i++) {
            String hex = Integer.toHexString(s.charAt(i) & 0xffff);
            for (int j = hex.length(); j < 4; j++) {
                buff.append('0');
            }
            buff.append(hex);
        }
        return buff.toString();
    }

    private static int locate(String search, String s, int start) {
        if (start < 0) {
            int i = s.length() + start;
            return s.lastIndexOf(search, i) + 1;
        } else {
            int i = (start == 0) ? 0 : start - 1;
            return s.indexOf(search, i) + 1;
        }
    }

    private static String right(String s, int count) {
        if (count < 0) {
            count = 0;
        } else if (count > s.length()) {
            count = s.length();
        }
        return s.substring(s.length() - count);
    }

    private static String left(String s, int count) {
        if (count < 0) {
            count = 0;
        } else if (count > s.length()) {
            count = s.length();
        }
        return s.substring(0, count);
    }

    private static String insert(String s1, int start, int length, String s2) {
        if (s1 == null) {
            return s2;
        }
        if (s2 == null) {
            return s1;
        }
        int len1 = s1.length();
        int len2 = s2.length();
        start--;
        if (start < 0 || length <= 0 || len2 == 0 || start > len1) {
            return s1;
        }
        if (start + length > len1) {
            length = len1 - start;
        }
        return s1.substring(0, start) + s2 + s1.substring(start + length);
    }

    private static String hexToRaw(String s) throws SQLException {
        // TODO function hextoraw compatibility with oracle
        int len = s.length();
        if (len % 4 != 0) {
            throw Message.getSQLException(ErrorCode.DATA_CONVERSION_ERROR_1, s);
        }
        StringBuffer buff = new StringBuffer(len / 4);
        for (int i = 0; i < len; i += 4) {
            try {
                char raw = (char) Integer.parseInt(s.substring(i, i + 4), 16);
                buff.append(raw);
            } catch (NumberFormatException e) {
                throw Message.getSQLException(ErrorCode.DATA_CONVERSION_ERROR_1, s);
            }
        }
        return buff.toString();
    }

    private static int getDifference(String s1, String s2) {
        // TODO function difference: compatibility with SQL Server and HSQLDB
        s1 = getSoundex(s1);
        s2 = getSoundex(s2);
        int e = 0;
        for (int i = 0; i < 4; i++) {
            if (s1.charAt(i) == s2.charAt(i)) {
                e++;
            }
        }
        return e;
    }

    private double roundmagic(double d) {
        if ((d < 0.0000000000001) && (d > -0.0000000000001)) {
            return 0.0;
        }
        if ((d > 1000000000000.) || (d < -1000000000000.)) {
            return d;
        }
        StringBuffer s = new StringBuffer();
        s.append(d);
        if (s.toString().indexOf("E") >= 0) {
            return d;
        }
        int len = s.length();
        if (len < 16) {
            return d;
        }
        if (s.toString().indexOf(".") > len - 3) {
            return d;
        }
        s.delete(len - 2, len);
        len -= 2;
        char c1 = s.charAt(len - 2);
        char c2 = s.charAt(len - 3);
        char c3 = s.charAt(len - 4);
        if ((c1 == '0') && (c2 == '0') && (c3 == '0')) {
            s.setCharAt(len - 1, '0');
        } else if ((c1 == '9') && (c2 == '9') && (c3 == '9')) {
            s.setCharAt(len - 1, '9');
            s.append('9');
            s.append('9');
            s.append('9');
        }
        return Double.valueOf(s.toString()).doubleValue();
    }

    private static String getSoundex(String s) {
        int len = s.length();
        char[] chars = new char[] { '0', '0', '0', '0' };
        char lastDigit = '0';
        for (int i = 0, j = 0; i < len && j < 4; i++) {
            char c = s.charAt(i);
            char newDigit = c > SOUNDEX_INDEX.length ? 0 : SOUNDEX_INDEX[c];
            if (newDigit != 0) {
                if (j == 0) {
                    chars[j++] = c;
                    lastDigit = newDigit;
                } else if (newDigit <= '6') {
                    if (newDigit != lastDigit) {
                        chars[j++] = newDigit;
                        lastDigit = newDigit;
                    }
                } else if (newDigit == '7') {
                    lastDigit = newDigit;
                }
            }
        }
        return new String(chars);
    }

    public int getType() {
        return dataType;
    }

    public void mapColumns(ColumnResolver resolver, int level) throws SQLException {
        for (int i = 0; i < args.length; i++) {
            args[i].mapColumns(resolver, level);
        }
    }

    protected void checkParameterCount(int len) throws SQLException {
        int min = 0, max = Integer.MAX_VALUE;
        switch (info.type) {
        case COALESCE:
        case CSVREAD:
        case LEAST:
        case GREATEST:
            min = 1;
            break;
        case NOW:
        case CURRENT_TIMESTAMP:
        case RAND:
            max = 1;
            break;
        case COMPRESS:
        case LTRIM:
        case RTRIM:
        case TRIM:
        case FILE_READ:
            min = 1;
            max = 2;
            break;
        case REPLACE:
        case LOCATE:
        case INSTR:
        case SUBSTR:
        case SUBSTRING:
        case LPAD:
        case RPAD:
            min = 2;
            max = 3;
            break;
        case CASE:
        case CONCAT:
        case CSVWRITE:
            min = 2;
            break;
        case XMLNODE:
            min = 1;
            max = 3;
            break;
        case FORMATDATETIME:
        case PARSEDATETIME:
            min = 2;
            max = 4;
            break;
        case CURRVAL:
        case NEXTVAL:
            min = 1;
            max = 2;
            break;
        default:
            throw Message.getInternalError("type=" + info.type);
        }
        boolean ok = (len >= min) && (len <= max);
        if (!ok) {
            throw Message.getSQLException(ErrorCode.INVALID_PARAMETER_COUNT_2, new String[] { info.name,
                    min + ".." + max });
        }
    }

    public void doneWithParameters() throws SQLException {
        if (info.parameterCount == VAR_ARGS) {
            int len = varArgs.size();
            checkParameterCount(len);
            args = new Expression[len];
            varArgs.toArray(args);
            varArgs = null;
        } else {
            int len = args.length;
            if (len > 0 && args[len - 1] == null) {
                throw Message
                        .getSQLException(ErrorCode.INVALID_PARAMETER_COUNT_2, new String[] { info.name, "" + len });
            }
        }
    }

    /**
     * Set the result data type of this function.
     * 
     * @param dataType the data type
     * @param precision the precision
     * @param scale the scale
     * @param displaySize the display size
     */
    public void setDataType(int dataType, long precision, int scale, int displaySize) {
        this.dataType = dataType;
        this.precision = precision;
        this.displaySize = displaySize;
        this.scale = scale;
    }

    public void setDataType(Column col) {
        dataType = col.getType();
        precision = col.getPrecision();
        displaySize = col.getDisplaySize();
        scale = col.getScale();
    }

    public Expression optimize(Session session) throws SQLException {
        boolean allConst = info.isDeterministic;
        for (int i = 0; i < args.length; i++) {
            Expression e = args[i].optimize(session);
            args[i] = e;
            if (!e.isConstant()) {
                allConst = false;
            }
        }
        Expression p0 = args.length < 1 ? null : args[0];
        switch (info.type) {
        case IFNULL:
        case NULLIF:
        case COALESCE:
        case LEAST:
        case GREATEST: {
            dataType = Value.UNKNOWN;
            scale = 0;
            precision = 0;
            displaySize = 0;
            for (int i = 0; i < args.length; i++) {
                Expression e = args[i];
                if (e != ValueExpression.NULL && e.getType() != Value.UNKNOWN) {
                    dataType = Value.getHigherOrder(dataType, e.getType());
                    scale = Math.max(scale, e.getScale());
                    precision = Math.max(precision, e.getPrecision());
                    displaySize = Math.max(displaySize, e.getDisplaySize());
                }
            }
            if (dataType == Value.UNKNOWN) {
                dataType = Value.STRING;
                scale = 0;
                precision = Integer.MAX_VALUE;
                displaySize = Integer.MAX_VALUE;
            }
            break;
        }
        case CASEWHEN:
            dataType = Value.getHigherOrder(args[1].ge