protected override void AnalyzeNode()

in ClrHeapAllocationsAnalyzer/ConcatenationAllocationAnalyzer.cs [23:62]
33 lines of code
8 McCabe index (conditional complexity)

        protected override void AnalyzeNode(SyntaxNodeAnalysisContext context)
        {
            var node = context.Node;
            var semanticModel = context.SemanticModel;
            Action<Diagnostic> reportDiagnostic = context.ReportDiagnostic;
            var cancellationToken = context.CancellationToken;
            string filePath = node.SyntaxTree.FilePath;
            var binaryExpressions = node.DescendantNodesAndSelf().OfType<BinaryExpressionSyntax>().Reverse(); // need inner most expressions

            int stringConcatenationCount = 0;
            foreach (var binaryExpression in binaryExpressions) {
                if (binaryExpression.Left == null || binaryExpression.Right == null) {
                    continue;
                }

                bool isConstant = semanticModel.GetConstantValue(binaryExpression, cancellationToken).HasValue;
                if (isConstant) {
                    continue;
                }

                var left = semanticModel.GetTypeInfo(binaryExpression.Left, cancellationToken);
                var leftConversion = semanticModel.GetConversion(binaryExpression.Left, cancellationToken);
                CheckTypeConversion(left, leftConversion, reportDiagnostic, binaryExpression.Left.GetLocation(), filePath);

                var right = semanticModel.GetTypeInfo(binaryExpression.Right, cancellationToken);
                var rightConversion = semanticModel.GetConversion(binaryExpression.Right, cancellationToken);
                CheckTypeConversion(right, rightConversion, reportDiagnostic, binaryExpression.Right.GetLocation(), filePath);

                // regular string allocation
                if (left.Type?.SpecialType == SpecialType.System_String || right.Type?.SpecialType == SpecialType.System_String) {
                      stringConcatenationCount++;   
                }
            }

            if (stringConcatenationCount > 3)
            {
                reportDiagnostic(Diagnostic.Create(StringConcatenationAllocationRule, node.GetLocation(), EmptyMessageArgs));
                HeapAllocationAnalyzerEventSource.Logger.StringConcatenationAllocation(filePath);
            }
        }