private static HashSet FudgeGraph()

in src/dotnet/PowerToys.CyclomaticComplexity/ComplexityAnalysisElementProblemAnalyzer.cs [161:200]

• 25 lines of code
• 8 McCabe index (conditional complexity)

    private static HashSet<IControlFlowEdge> FudgeGraph(IControlFlowGraph graph, HashSet<IControlFlowEdge> edges)
    {
      // The C# graph treats the unary negation operator `!` as a conditional. It's not,
      // but having it so means that the CC can be way higher than it should be.
      var dodgyEdges = new HashSet<IControlFlowEdge>(new EdgeEqualityComparer());

      // Look at all of the non-leaf elements (the graph is a tree as well as a graph.
      // The tree represents the structure of the code, with the control flow graph
      // running through it)
      foreach (var element in graph.AllElements.Where(e => e.Children.Count != 0))
      {
        var unaryOperatorExpression = element.SourceElement as IUnaryOperatorExpression;
        if (unaryOperatorExpression != null && unaryOperatorExpression.UnaryOperatorType == UnaryOperatorType.EXCL)
        {
          // The unary operator shouldn't have 2 exits. It's not a conditional. If it does,
          // remove one of the edges, and it's path, from the collected edges.
          if (element.Exits.Count == 2)
          {
            var edge = element.Exits.FirstOrDefault();
            do
            {
              dodgyEdges.Add(edge);

              // Get the source of the exit edge. This is the node in the control flow graph,
              // not the element in the program structure tree.
              var source = edge.Source;
              edge = null;

              // Walk back to the control flow graph node that represents the exit of the
              // dodgy condition, so keep going until we have an element with 2 exits.
              if (source.Entries.Count == 1 && source.Exits.Count == 1)
                edge = source.Entries.FirstOrDefault();
            } while (edge != null);
          }
        }
      }

      edges.ExceptWith(dodgyEdges);
      return edges;
    }