void _fetchNextToken()

in lib/src/scanner.dart [357:478]
109 lines of code
38 McCabe index (conditional complexity)

  void _fetchNextToken() {
    if (!_streamStartProduced) {
      _fetchStreamStart();
      return;
    }

    _scanToNextToken();
    _staleSimpleKeys();
    _unrollIndent(_scanner.column);

    if (_scanner.isDone) {
      _fetchStreamEnd();
      return;
    }

    if (_scanner.column == 0) {
      if (_scanner.peekChar() == PERCENT) {
        _fetchDirective();
        return;
      }

      if (_isBlankOrEndAt(3)) {
        if (_scanner.matches('---')) {
          _fetchDocumentIndicator(TokenType.documentStart);
          return;
        }

        if (_scanner.matches('...')) {
          _fetchDocumentIndicator(TokenType.documentEnd);
          return;
        }
      }
    }

    switch (_scanner.peekChar()) {
      case LEFT_SQUARE:
        _fetchFlowCollectionStart(TokenType.flowSequenceStart);
        return;
      case LEFT_CURLY:
        _fetchFlowCollectionStart(TokenType.flowMappingStart);
        return;
      case RIGHT_SQUARE:
        _fetchFlowCollectionEnd(TokenType.flowSequenceEnd);
        return;
      case RIGHT_CURLY:
        _fetchFlowCollectionEnd(TokenType.flowMappingEnd);
        return;
      case COMMA:
        _fetchFlowEntry();
        return;
      case ASTERISK:
        _fetchAnchor(anchor: false);
        return;
      case AMPERSAND:
        _fetchAnchor();
        return;
      case EXCLAMATION:
        _fetchTag();
        return;
      case SINGLE_QUOTE:
        _fetchFlowScalar(singleQuote: true);
        return;
      case DOUBLE_QUOTE:
        _fetchFlowScalar();
        return;
      case VERTICAL_BAR:
        if (!_inBlockContext) _invalidScalarCharacter();
        _fetchBlockScalar(literal: true);
        return;
      case RIGHT_ANGLE:
        if (!_inBlockContext) _invalidScalarCharacter();
        _fetchBlockScalar();
        return;
      case PERCENT:
      case AT:
      case GRAVE_ACCENT:
        _invalidScalarCharacter();
        return;

      // These characters may sometimes begin plain scalars.
      case HYPHEN:
        if (_isPlainCharAt(1)) {
          _fetchPlainScalar();
        } else {
          _fetchBlockEntry();
        }
        return;
      case QUESTION:
        if (_isPlainCharAt(1)) {
          _fetchPlainScalar();
        } else {
          _fetchKey();
        }
        return;
      case COLON:
        if (!_inBlockContext && _tokens.isNotEmpty) {
          // If a colon follows a "JSON-like" value (an explicit map or list, or
          // a quoted string) it isn't required to have whitespace after it
          // since it unambiguously describes a map.
          var token = _tokens.last;
          if (token.type == TokenType.flowSequenceEnd ||
              token.type == TokenType.flowMappingEnd ||
              (token.type == TokenType.scalar &&
                  (token as ScalarToken).style.isQuoted)) {
            _fetchValue();
            return;
          }
        }

        if (_isPlainCharAt(1)) {
          _fetchPlainScalar();
        } else {
          _fetchValue();
        }
        return;
      default:
        if (!_isNonBreak) _invalidScalarCharacter();

        _fetchPlainScalar();
        return;
    }
  }