Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Writer/Xls/Parser.php
private function match($token)
    {
        switch ($token) {
            case '+':
            case '-':
            case '*':
            case '/':
            case '(':
            case ')':
            case ',':
            case ';':
            case '>=':
            case '<=':
            case '=':
            case '<>':
            case '^':
            case '&':
            case '%':
                return $token;

                break;
            case '>':
                if ($this->lookAhead == '=') { // it's a GE token
                    break;
                }

                return $token;

                break;
            case '<':
                // it's a LE or a NE token
                if (($this->lookAhead == '=') or ($this->lookAhead == '>')) {
                    break;
                }

                return $token;

                break;
            default:
                // if it's a reference A1 or $A$1 or $A1 or A$1
                if (preg_match('/^\$?[A-Ia-i]?[A-Za-z]\$?\d+$/', $token) and !preg_match('/\d/', $this->lookAhead) and ($this->lookAhead != ':') and ($this->lookAhead != '.') and ($this->lookAhead != '!')) {
                    return $token;
                } elseif (preg_match('/^' . self::REGEX_SHEET_TITLE_UNQUOTED . '(\\:' . self::REGEX_SHEET_TITLE_UNQUOTED . ')?\\!\$?[A-Ia-i]?[A-Za-z]\$?\\d+$/u', $token) and !preg_match('/\d/', $this->lookAhead) and ($this->lookAhead != ':') and ($this->lookAhead != '.')) {
                    // If it's an external reference (Sheet1!A1 or Sheet1:Sheet2!A1 or Sheet1!$A$1 or Sheet1:Sheet2!$A$1)
                    return $token;
                } elseif (preg_match("/^'" . self::REGEX_SHEET_TITLE_QUOTED . '(\\:' . self::REGEX_SHEET_TITLE_QUOTED . ")?'\\!\\$?[A-Ia-i]?[A-Za-z]\\$?\\d+$/u", $token) and !preg_match('/\d/', $this->lookAhead) and ($this->lookAhead != ':') and ($this->lookAhead != '.')) {
                    // If it's an external reference ('Sheet1'!A1 or 'Sheet1:Sheet2'!A1 or 'Sheet1'!$A$1 or 'Sheet1:Sheet2'!$A$1)
                    return $token;
                } elseif (preg_match('/^(\$)?[A-Ia-i]?[A-Za-z](\$)?\d+:(\$)?[A-Ia-i]?[A-Za-z](\$)?\d+$/', $token) && !preg_match('/\d/', $this->lookAhead)) {
                    // if it's a range A1:A2 or $A$1:$A$2
                    return $token;
                } elseif (preg_match('/^' . self::REGEX_SHEET_TITLE_UNQUOTED . '(\\:' . self::REGEX_SHEET_TITLE_UNQUOTED . ')?\\!\$?([A-Ia-i]?[A-Za-z])?\$?\\d+:\$?([A-Ia-i]?[A-Za-z])?\$?\\d+$/u', $token) and !preg_match('/\d/', $this->lookAhead)) {
                    // If it's an external range like Sheet1!A1:B2 or Sheet1:Sheet2!A1:B2 or Sheet1!$A$1:$B$2 or Sheet1:Sheet2!$A$1:$B$2
                    return $token;
                } elseif (preg_match("/^'" . self::REGEX_SHEET_TITLE_QUOTED . '(\\:' . self::REGEX_SHEET_TITLE_QUOTED . ")?'\\!\\$?([A-Ia-i]?[A-Za-z])?\\$?\\d+:\\$?([A-Ia-i]?[A-Za-z])?\\$?\\d+$/u", $token) and !preg_match('/\d/', $this->lookAhead)) {
                    // If it's an external range like 'Sheet1'!A1:B2 or 'Sheet1:Sheet2'!A1:B2 or 'Sheet1'!$A$1:$B$2 or 'Sheet1:Sheet2'!$A$1:$B$2
                    return $token;
                } elseif (is_numeric($token) and (!is_numeric($token . $this->lookAhead) or ($this->lookAhead == '')) and ($this->lookAhead != '!') and ($this->lookAhead != ':')) {
                    // If it's a number (check that it's not a sheet name or range)
                    return $token;
                } elseif (preg_match('/"([^"]|""){0,255}"/', $token) and $this->lookAhead != '"' and (substr_count($token, '"') % 2 == 0)) {
                    // If it's a string (of maximum 255 characters)
                    return $token;
                } elseif (preg_match('/^#[A-Z0\\/]{3,5}[!?]{1}$/', $token) or $token == '#N/A') {
                    // If it's an error code
                    return $token;
                } elseif (preg_match("/^[A-Z0-9\xc0-\xdc\\.]+$/i", $token) and ($this->lookAhead == '(')) {
                    // if it's a function call
                    return $token;
                } elseif (substr($token, -1) == ')') {
                    //    It's an argument of some description (e.g. a named range),
                    //        precise nature yet to be determined
                    return $token;
                }

                return '';
        }
    }
private function match($token)
    {
        switch ($token) {
            case '+':
            case '-':
            case '*':
            case '/':
            case '(':
            case ')':
            case ',':
            case ';':
            case '>=':
            case '<=':
            case '=':
            case '<>':
            case '^':
            case '&':
            case '%':
                return $token;

                break;
            case '>':
                if ($this->lookAhead == '=') { // it's a GE token
                    break;
                }

                return $token;

                break;
            case '<':
                // it's a LE or a NE token
                if (($this->lookAhead == '=') or ($this->lookAhead == '>')) {
                    break;
                }

                return $token;

                break;
            default:
                // if it's a reference A1 or $A$1 or $A1 or A$1
                if (preg_match('/^\$?[A-Ia-i]?[A-Za-z]\$?\d+$/', $token) and !preg_match('/\d/', $this->lookAhead) and ($this->lookAhead != ':') and ($this->lookAhead != '.') and ($this->lookAhead != '!')) {
                    return $token;
                } elseif (preg_match('/^' . self::REGEX_SHEET_TITLE_UNQUOTED . '(\\:' . self::REGEX_SHEET_TITLE_UNQUOTED . ')?\\!\$?[A-Ia-i]?[A-Za-z]\$?\\d+$/u', $token) and !preg_match('/\d/', $this->lookAhead) and ($this->lookAhead != ':') and ($this->lookAhead != '.')) {
                    // If it's an external reference (Sheet1!A1 or Sheet1:Sheet2!A1 or Sheet1!$A$1 or Sheet1:Sheet2!$A$1)
                    return $token;
                } elseif (preg_match("/^'" . self::REGEX_SHEET_TITLE_QUOTED . '(\\:' . self::REGEX_SHEET_TITLE_QUOTED . ")?'\\!\\$?[A-Ia-i]?[A-Za-z]\\$?\\d+$/u", $token) and !preg_match('/\d/', $this->lookAhead) and ($this->lookAhead != ':') and ($this->lookAhead != '.')) {
                    // If it's an external reference ('Sheet1'!A1 or 'Sheet1:Sheet2'!A1 or 'Sheet1'!$A$1 or 'Sheet1:Sheet2'!$A$1)
                    return $token;
                } elseif (preg_match('/^(\$)?[A-Ia-i]?[A-Za-z](\$)?\d+:(\$)?[A-Ia-i]?[A-Za-z](\$)?\d+$/', $token) && !preg_match('/\d/', $this->lookAhead)) {
                    // if it's a range A1:A2 or $A$1:$A$2
                    return $token;
                } elseif (preg_match('/^' . self::REGEX_SHEET_TITLE_UNQUOTED . '(\\:' . self::REGEX_SHEET_TITLE_UNQUOTED . ')?\\!\$?([A-Ia-i]?[A-Za-z])?\$?\\d+:\$?([A-Ia-i]?[A-Za-z])?\$?\\d+$/u', $token) and !preg_match('/\d/', $this->lookAhead)) {
                    // If it's an external range like Sheet1!A1:B2 or Sheet1:Sheet2!A1:B2 or Sheet1!$A$1:$B$2 or Sheet1:Sheet2!$A$1:$B$2
                    return $token;
                } elseif (preg_match("/^'" . self::REGEX_SHEET_TITLE_QUOTED . '(\\:' . self::REGEX_SHEET_TITLE_QUOTED . ")?'\\!\\$?([A-Ia-i]?[A-Za-z])?\\$?\\d+:\\$?([A-Ia-i]?[A-Za-z])?\\$?\\d+$/u", $token) and !preg_match('/\d/', $this->lookAhead)) {
                    // If it's an external range like 'Sheet1'!A1:B2 or 'Sheet1:Sheet2'!A1:B2 or 'Sheet1'!$A$1:$B$2 or 'Sheet1:Sheet2'!$A$1:$B$2
                    return $token;
                } elseif (is_numeric($token) and (!is_numeric($token . $this->lookAhead) or ($this->lookAhead == '')) and ($this->lookAhead != '!') and ($this->lookAhead != ':')) {
                    // If it's a number (check that it's not a sheet name or range)
                    return $token;
                } elseif (preg_match('/"([^"]|""){0,255}"/', $token) and $this->lookAhead != '"' and (substr_count($token, '"') % 2 == 0)) {
                    // If it's a string (of maximum 255 characters)
                    return $token;
                } elseif (preg_match('/^#[A-Z0\\/]{3,5}[!?]{1}$/', $token) or $token == '#N/A') {
                    // If it's an error code
                    return $token;
                } elseif (preg_match("/^[A-Z0-9\xc0-\xdc\\.]+$/i", $token) and ($this->lookAhead == '(')) {
                    // if it's a function call
                    return $token;
                } elseif (substr($token, -1) == ')') {
                    //    It's an argument of some description (e.g. a named range),
                    //        precise nature yet to be determined
                    return $token;
                }

                return '';
        }
    }
Checks if it's a valid token.

@param mixed $token the token to check

@return mixed The checked token or false on failure