void _writeMultilineHighlights()

in lib/src/highlighter.dart [283:345]
60 lines of code
21 McCabe index (conditional complexity)

  void _writeMultilineHighlights(
      _Line line, List<_Highlight?> highlightsByColumn,
      {_Highlight? current}) {
    // Whether we've written a sidebar indicator for opening a new span on this
    // line, and which color should be used for that indicator's rightward line.
    var openedOnThisLine = false;
    String? openedOnThisLineColor;

    final currentColor = current == null
        ? null
        : current.isPrimary
            ? _primaryColor
            : _secondaryColor;
    var foundCurrent = false;
    for (var highlight in highlightsByColumn) {
      final startLine = highlight?.span.start.line;
      final endLine = highlight?.span.end.line;
      if (current != null && highlight == current) {
        foundCurrent = true;
        assert(startLine == line.number || endLine == line.number);
        _colorize(() {
          _buffer.write(startLine == line.number
              ? glyph.topLeftCorner
              : glyph.bottomLeftCorner);
        }, color: currentColor);
      } else if (foundCurrent) {
        _colorize(() {
          _buffer.write(highlight == null ? glyph.horizontalLine : glyph.cross);
        }, color: currentColor);
      } else if (highlight == null) {
        if (openedOnThisLine) {
          _colorize(() => _buffer.write(glyph.horizontalLine),
              color: openedOnThisLineColor);
        } else {
          _buffer.write(' ');
        }
      } else {
        _colorize(() {
          final vertical = openedOnThisLine ? glyph.cross : glyph.verticalLine;
          if (current != null) {
            _buffer.write(vertical);
          } else if (startLine == line.number) {
            _colorize(() {
              _buffer
                  .write(glyph.glyphOrAscii(openedOnThisLine ? '┬' : '┌', '/'));
            }, color: openedOnThisLineColor);
            openedOnThisLine = true;
            openedOnThisLineColor ??=
                highlight.isPrimary ? _primaryColor : _secondaryColor;
          } else if (endLine == line.number &&
              highlight.span.end.column == line.text.length) {
            _buffer.write(highlight.label == null
                ? glyph.glyphOrAscii('└', '\\')
                : vertical);
          } else {
            _colorize(() {
              _buffer.write(vertical);
            }, color: openedOnThisLineColor);
          }
        }, color: highlight.isPrimary ? _primaryColor : _secondaryColor);
      }
    }
  }