src/Domain/Value/Identifier/Uri.php
protected static function isValidScheme(?string $scheme): bool
    {
        // http://tools.ietf.org/html/rfc3986#section-3
        // The scheme and path components are required, though the path may be
        // empty (no characters)
        if ($scheme === null || $scheme === '') {
            return false;
        }

        return !!preg_match(static::SCHEME_PATTERN, $scheme);
    }
protected static function isValidScheme(?string $scheme): bool
    {
        // http://tools.ietf.org/html/rfc3986#section-3
        // The scheme and path components are required, though the path may be
        // empty (no characters)
        if ($scheme === null || $scheme === '') {
            return false;
        }

        return !!preg_match(static::SCHEME_PATTERN, $scheme);
    }
protected static function isValidScheme ( ? string $ scheme ) : bool { // http://tools.ietf.org/html/rfc3986#section-3 // The scheme and path components are required, though the path may be // empty (no characters) if ( $ scheme === null || $ scheme === '' ) { return false ; } return ! ! preg_match ( static :: SCHEME_PATTERN , $ scheme ) ; }
Checks if a scheme is valid

@param string|null $scheme The scheme

@return bool
Checks if a scheme is valid