static List parseHeader()

in lib/src/authentication_challenge.dart [36:90]
37 lines of code
7 McCabe index (conditional complexity)

  static List<AuthenticationChallenge> parseHeader(String header) =>
      wrapFormatException('authentication header', header, () {
        final scanner = StringScanner(header);
        scanner.scan(whitespace);
        final challenges = parseList(scanner, () {
          final scheme = _scanScheme(scanner, whitespaceName: '" " or "="');

          // Manually parse the inner list. We need to do some lookahead to
          // disambiguate between an auth param and another challenge.
          final params = <String, String>{};

          // Consume initial empty values.
          while (scanner.scan(',')) {
            scanner.scan(whitespace);
          }

          _scanAuthParam(scanner, params);

          var beforeComma = scanner.position;
          while (scanner.scan(',')) {
            scanner.scan(whitespace);

            // Empty elements are allowed, but excluded from the results.
            if (scanner.matches(',') || scanner.isDone) continue;

            scanner.expect(token, name: 'a token');
            final name = scanner.lastMatch![0]!;
            scanner.scan(whitespace);

            // If there's no "=", then this is another challenge rather than a
            // parameter for the current challenge.
            if (!scanner.scan('=')) {
              scanner.position = beforeComma;
              break;
            }

            scanner.scan(whitespace);

            if (scanner.scan(token)) {
              params[name] = scanner.lastMatch![0]!;
            } else {
              params[name] = expectQuotedString(scanner,
                  name: 'a token or a quoted string');
            }

            scanner.scan(whitespace);
            beforeComma = scanner.position;
          }

          return AuthenticationChallenge(scheme, params);
        });

        scanner.expectDone();
        return challenges;
      });