Token _scanBlockScalar()

in lib/src/scanner.dart [1100:1225]
77 lines of code
27 McCabe index (conditional complexity)

  Token _scanBlockScalar({bool literal = false}) {
    var start = _scanner.state;

    // Eat the indicator '|' or '>'.
    _scanner.readChar();

    // Check for a chomping indicator.
    var chomping = _Chomping.clip;
    var increment = 0;
    var char = _scanner.peekChar();
    if (char == PLUS || char == HYPHEN) {
      chomping = char == PLUS ? _Chomping.keep : _Chomping.strip;
      _scanner.readChar();

      // Check for an indentation indicator.
      if (_isDigit) {
        // Check that the indentation is greater than 0.
        if (_scanner.peekChar() == NUMBER_0) {
          throw YamlException('0 may not be used as an indentation indicator.',
              _scanner.spanFrom(start));
        }

        increment = _scanner.readChar() - NUMBER_0;
      }
    } else if (_isDigit) {
      // Do the same as above, but in the opposite order.
      if (_scanner.peekChar() == NUMBER_0) {
        throw YamlException('0 may not be used as an indentation indicator.',
            _scanner.spanFrom(start));
      }

      increment = _scanner.readChar() - NUMBER_0;

      char = _scanner.peekChar();
      if (char == PLUS || char == HYPHEN) {
        chomping = char == PLUS ? _Chomping.keep : _Chomping.strip;
        _scanner.readChar();
      }
    }

    // Eat whitespace and comments to the end of the line.
    _skipBlanks();
    _skipComment();

    // Check if we're at the end of the line.
    if (!_isBreakOrEnd) {
      throw YamlException(
          'Expected comment or line break.', _scanner.emptySpan);
    }

    _skipLine();

    // If the block scalar has an explicit indentation indicator, add that to
    // the current indentation to get the indentation level for the scalar's
    // contents.
    var indent = 0;
    if (increment != 0) {
      indent = _indent >= 0 ? _indent + increment : increment;
    }

    // Scan the leading line breaks to determine the indentation level if
    // needed.
    var pair = _scanBlockScalarBreaks(indent);
    indent = pair.first;
    var trailingBreaks = pair.last;

    // Scan the block scalar contents.
    var buffer = StringBuffer();
    var leadingBreak = '';
    var leadingBlank = false;
    var trailingBlank = false;
    var end = _scanner.state;
    while (_scanner.column == indent && !_scanner.isDone) {
      // Check for a document indicator. libyaml doesn't do this, but the spec
      // mandates it. See example 9.5:
      // http://yaml.org/spec/1.2/spec.html#id2801606.
      if (_isDocumentIndicator) break;

      // We are at the beginning of a non-empty line.

      // Is there trailing whitespace?
      trailingBlank = _isBlank;

      // Check if we need to fold the leading line break.
      if (!literal &&
          leadingBreak.isNotEmpty &&
          !leadingBlank &&
          !trailingBlank) {
        // Do we need to join the lines with a space?
        if (trailingBreaks.isEmpty) buffer.writeCharCode(SP);
      } else {
        buffer.write(leadingBreak);
      }
      leadingBreak = '';

      // Append the remaining line breaks.
      buffer.write(trailingBreaks);

      // Is there leading whitespace?
      leadingBlank = _isBlank;

      var startPosition = _scanner.position;
      while (!_isBreakOrEnd) {
        _scanner.readChar();
      }
      buffer.write(_scanner.substring(startPosition));
      end = _scanner.state;

      // libyaml always reads a line here, but this breaks on block scalars at
      // the end of the document that end without newlines. See example 8.1:
      // http://yaml.org/spec/1.2/spec.html#id2793888.
      if (!_scanner.isDone) leadingBreak = _readLine();

      // Eat the following indentation and spaces.
      var pair = _scanBlockScalarBreaks(indent);
      indent = pair.first;
      trailingBreaks = pair.last;
    }

    // Chomp the tail.
    if (chomping != _Chomping.strip) buffer.write(leadingBreak);
    if (chomping == _Chomping.keep) buffer.write(trailingBreaks);

    return ScalarToken(_scanner.spanFrom(start, end), buffer.toString(),
        literal ? ScalarStyle.LITERAL : ScalarStyle.FOLDED);
  }