DataDictionary.Interpreter.BinaryExpression.GetCalled C# (CSharp) Method

        public override ICallable GetCalled(InterpretationContext context, ExplanationPart explain)
        {
            ICallable retVal = null;

            Function leftFunction = Left.GetCalled(context, explain) as Function;
            List<Parameter> unboundLeft = getUnboundParameter(context, leftFunction);
            if (leftFunction == null || unboundLeft.Count == 0)
            {
                leftFunction = Left.GetValue(context, explain) as Function;
                unboundLeft = getUnboundParametersFromValue(leftFunction);
            }

            Function rightFunction = Right.GetCalled(context, explain) as Function;
            List<Parameter> unboundRight = getUnboundParameter(context, rightFunction);
            if (rightFunction == null || unboundRight.Count == 0)
            {
                rightFunction = Right.GetValue(context, explain) as Function;
                unboundRight = getUnboundParametersFromValue(rightFunction);
            }

            int max = Math.Max(unboundLeft.Count, unboundRight.Count);
            if (max == 0)
            {
                if (leftFunction == null)
                {
                    if (rightFunction == null)
                    {
                        retVal = GetValue(context, explain) as ICallable;
                    }
                    else
                    {
                        if (rightFunction.FormalParameters.Count == 1)
                        {
                            // ReSharper disable once ExpressionIsAlwaysNull
                            retVal = CreateGraphResult(context, leftFunction, unboundLeft, rightFunction, unboundRight,
                                explain);
                        }
                        else if (rightFunction.FormalParameters.Count == 2)
                        {
                            // ReSharper disable once ExpressionIsAlwaysNull
                            retVal = CreateSurfaceResult(context, leftFunction, unboundLeft, rightFunction, unboundRight,
                                explain);
                        }
                        else
                        {
                            retVal = GetValue(context, explain) as ICallable;
                        }
                    }
                }
                else if (rightFunction == null)
                {
                    if (leftFunction.FormalParameters.Count == 1)
                    {
                        // ReSharper disable once ExpressionIsAlwaysNull
                        retVal = CreateGraphResult(context, leftFunction, unboundLeft, rightFunction, unboundRight,
                            explain);
                    }
                    else if (leftFunction.FormalParameters.Count == 2)
                    {
                        // ReSharper disable once ExpressionIsAlwaysNull
                        retVal = CreateSurfaceResult(context, leftFunction, unboundLeft, rightFunction, unboundRight,
                            explain);
                    }
                    else
                    {
                        retVal = GetValue(context, explain) as ICallable;
                    }
                }
                else
                {
                    retVal = GetValue(context, explain) as ICallable;
                }

                if (retVal == null)
                {
                    AddError("Cannot create ICallable when there are no unbound parameters", RuleChecksEnum.ExecutionFailed);
                }
            }
            else if (max == 1)
            {
                retVal = CreateGraphResult(context, leftFunction, unboundLeft, rightFunction, unboundRight, explain);
            }
            else if (max == 2)
            {
                retVal = CreateSurfaceResult(context, leftFunction, unboundLeft, rightFunction, unboundRight, explain);
            }
            else
            {
                AddError("Cannot create graph or structure when more that 2 parameters are unbound", RuleChecksEnum.ExecutionFailed);
            }

            return retVal;
        }