SourceMapSpan? spanFor()

in lib/parser.dart [524:561]
33 lines of code
7 McCabe index (conditional complexity)

  SourceMapSpan? spanFor(int line, int column,
      {Map<String, SourceFile>? files, String? uri}) {
    var entry = _findColumn(line, column, _findLine(line));
    if (entry == null) return null;

    var sourceUrlId = entry.sourceUrlId;
    if (sourceUrlId == null) return null;

    var url = urls[sourceUrlId];
    if (sourceRoot != null) {
      url = '$sourceRoot$url';
    }

    var sourceNameId = entry.sourceNameId;
    var file = files?[url];
    if (file != null) {
      var start = file.getOffset(entry.sourceLine!, entry.sourceColumn);
      if (sourceNameId != null) {
        var text = names[sourceNameId];
        return SourceMapFileSpan(file.span(start, start + text.length),
            isIdentifier: true);
      } else {
        return SourceMapFileSpan(file.location(start).pointSpan());
      }
    } else {
      var start = SourceLocation(0,
          sourceUrl: _mapUrl?.resolve(url) ?? url,
          line: entry.sourceLine,
          column: entry.sourceColumn);

      // Offset and other context is not available.
      if (sourceNameId != null) {
        return SourceMapSpan.identifier(start, names[sourceNameId]);
      } else {
        return SourceMapSpan(start, start, '');
      }
    }
  }