tag
     */
    public static function format($string, $highlight=true)
    {
        // This variable will be populated with formatted html
        $return = '';

        // Configuration values
        $tab = self::$tab;

        // Starting values
        $indent = 1;
        $newline = false;
        $indented = false;
        $extra_indent = 0;

        // Tokenize String
        $tokens = self::tokenize($string);

        foreach ($tokens as $i=>$token) {
            // Get highlighted token if doing syntax highlighting
            if ($highlight) {
                $highlighted = self::highlightToken($token);
            } else { // If returning raw text
                $highlighted = $token['token'];
            }

            // Don't process whitespace
            if ($token['type'] === 'whitespace') {
                continue;
            }

            // Display comments directly where they appear in the source
            if ($token['type'] === 'comment' || $token['type'] === 'block comment') {
                if ($token['type'] === 'block comment') {
                    $return .= "\n" . str_repeat($tab, $indent);
                }

                $return .= $highlighted;
                $newline = true;
                continue;
            }

            // If this token decreases the indent level
            if ($token['type'] === 'special reserved' || $token['type'] === ')') {
                if ($indented) {
                    ++$extra_indent;
                } elseif ($indent && ($token['type'] === 'special reserved' || $indent > 1)) {
                    --$indent;

                    if ($token['type'] === ')' && $extra_indent) {
                        $indent -= $extra_indent;
                        $extra_indent = 0;
                    }
                } else { // If there are mismatched parentheses
                    if ($highlight) {
                        $return .= self::highlightError(htmlentities($token['token'])).' ';
                    } else {
                        $return .= $highlighted;
                    }

                    continue;
                }
            }

            // If we need a new line before the token
            if ($newline || ($token['type'] === ')' || $token['type'] === 'special reserved')) {
                $newline = false;
                $return .= "\n" . str_repeat($tab, $indent);
            }

            // If we need a new line after the token
            if ($token['type'] === ',' || $token['type'] === '(' || $token['type'] === 'special reserved') {
                $newline = true;
            }

            // If this token increases the indent level
            if ($token['type'] === 'special reserved' || $token['type'] === '(') {
                ++$indent;
                $indented = true;
            } else {
                $indented = false;
            }

            // If the token shouldn't have a space before it
            if ($token['token'] === '.' || $token['token'] === ',' || $token['token'] === ';') {
                $return = rtrim($return, ' ');
            }

            //if this is an opening parentheses, take out the preceding space unless there was whitespace there in the
            //original query
            if ($token['token'][0] === '(' && isset($tokens[$i-1]) && $tokens[$i-1]['type'] !== 'whitespace') {
                $return = rtrim($return,' ');
            }

            $return .= $highlighted.' ';

            // If the token shouldn't have a space after it
            if ($token['token'] === '(' || $token['token'] === '.') {
                $return = rtrim($return,' ');
            }
        }

        // If there are unmatched parentheses
        if ($highlight && $indent !== 1) {
            $return .= "\n".self::highlightError("WARNING: unclosed parentheses or section");
        }

        if ($highlight) {
            return "
" . trim($return) . "
";
        }

        return trim($return);
    }

    /**
     * Add syntax highlighting to a SQL string
     *
     * @param String $string The SQL string
     *
     * @throws Exception when there is a problem tokenizing the input string
     *
     * @return String The SQL string with HTML styles applied
     */
    public static function highlight($string)
    {
        $tokens = self::tokenize($string);

        $return = '';

        foreach ($tokens as $token) {
            $return .= self::highlightToken($token);
        }

        return "
" . trim($return) . "
";
    }

    /**
     * Split a SQL string into multiple queries.
     * Uses ";" as a query delimiter.
     *
     * @param String $string The SQL string
     *
     * @throws Exception when there is a problem tokenizing the input string
     *
     * @return Array An array of individual query strings without trailing semicolons
     */
    public static function splitQuery($string)
    {
        // Comments between queries cause problems, so remove them first
        $string = self::removeComments($string);

        $queries = array();
        $current_query = '';

        $tokens = self::tokenize($string);

        foreach ($tokens as $token) {
            // If this is a query separator
            if ($token['token'] === ';') {
                if (trim($current_query)) {
                    $queries[] = trim($current_query);
                }
                $current_query = '';
                continue;
            }

            $current_query .= $token['token'];
        }

        if (trim($current_query)) {
            $queries[] = trim($current_query);
        }

        return $queries;
    }

    /**
     * Remove all comments from a SQL string
     *
     * @param String $string The SQL string
     *
     * @throws Exception when there is a problem tokenizing the input string
     *
     * @return String The SQL string without comments
     */
    public static function removeComments($string)
    {
        $result = '';

        $tokens = self::tokenize($string);

        foreach ($tokens as $token) {
            // Skip comment tokens
            if ($token['type'] === 'comment' || $token['type'] === 'block comment') {
                continue;
            }

            $result .= $token['token'];
        }

        return $result;
    }

    /**
     * Highlights a token depending on its type.
     *
     * @param Array $token An associative array containing 'token' and 'type' keys.
     *
     * @return String HTML code of the highlighted token.
     */
    protected static function highlightToken($token)
    {
        $type = $token['type'];
        $token = htmlentities($token['token']);

        switch ($type) {
                case 'backtick quote':
                case 'quote':
                    return self::highlightQuote($token, $type);
                case 'reserved':
                case 'special reserved':
                    return self::highlightReservedWord($token);
                case '(':
                case ')':
                    return $token;
                case 'number':
                    return self::highlightNumber($token);
                case 'boundary':
                case '.':
                case ',':
                    return self::highlightBoundary($token);
                case 'comment':
                case 'block comment':
                    return self::highlightComment($token);
                default:
                    return self::highlightDefault($token);
            }
    }

    /**
     * Highlights a quoted string
     *
     * @param String $value The token's value
     * @param String $type  The token's type
     *
     * @return String HTML code of the highlighted token.
     */
    protected static function highlightQuote($value, $type)
    {
        if ($type === 'backtick quote') {
            return "" . $value . "";
        }

        return "" . $value . "";
    }

    /**
     * Highlights a reserved word
     *
     * @param String $value The token's value
     *
     * @return String HTML code of the highlighted token.
     */
    protected static function highlightReservedWord($value)
    {
        return "" . $value . "";
    }

    /**
     * Highlights a boundary token
     *
     * @param String $value The token's value
     *
     * @return String HTML code of the highlighted token.
     */
    protected static function highlightBoundary($value)
    {
        return "" . $value . "";
    }

    /**
     * Highlights a number
     *
     * @param String $value The token's value
     *
     * @return String HTML code of the highlighted token.
     */
    protected static function highlightNumber($value)
    {
        return "" . $value . "";
    }

    /**
     * Highlights an error
     *
     * @param String $value The token's value
     *
     * @return String HTML code of the highlighted token.
     */
    protected static function highlightError($value)
    {
        return "" . $value . "";
    }

    /**
     * Highlights a comment
     *
     * @param String $value The token's value
     *
     * @return String HTML code of the highlighted token.
     */
    protected static function highlightComment($value)
    {
        return "" . $value . "";
    }

    /**
     * Highlights a generic token
     *
     * @param String $value The token's value
     *
     * @return String HTML code of the highlighted token.
     */
    protected static function highlightDefault($value)
    {
        return "" . $value . "";
    }

    /**
     * Helper function for sorting the list of reserved words by length
     *
     * @param String $a The first string
     * @param String $b The second string
     *
     * @return int The comparison of the string lengths
     */
    private static function sortLength($a, $b)
    {
        return strlen($b) - strlen($a);
    }
}