AutoMapper.Execution.TypeMapPlanBuilder.CreateMapperFunc C# (CSharp) Method

        private Expression CreateMapperFunc(Expression assignmentFunc)
        {
            var mapperFunc = assignmentFunc;

            if(_typeMap.Condition != null)
            {
                mapperFunc =
                    Condition(_typeMap.Condition.Body,
                        mapperFunc, Default(_typeMap.DestinationTypeToUse));
                //mapperFunc = (source, context, destFunc) => _condition(context) ? inner(source, context, destFunc) : default(TDestination);
            }

            if(_typeMap.MaxDepth > 0)
            {
                mapperFunc = Condition(
                    LessThanOrEqual(
                        Call(_context, ((MethodCallExpression)GetTypeDepthInfo.Body).Method, Constant(_typeMap.Types)),
                        Constant(_typeMap.MaxDepth)
                    ),
                    mapperFunc,
                    Default(_typeMap.DestinationTypeToUse));
                //mapperFunc = (source, context, destFunc) => context.GetTypeDepth(types) <= maxDepth ? inner(source, context, destFunc) : default(TDestination);
            }

            if(_typeMap.Profile.AllowNullDestinationValues && !_typeMap.SourceType.IsValueType())
            {
                mapperFunc =
                    Condition(Equal(_source, Default(_typeMap.SourceType)),
                        Default(_typeMap.DestinationTypeToUse), mapperFunc.RemoveIfNotNull(_source));
                //mapperFunc = (source, context, destFunc) => source == default(TSource) ? default(TDestination) : inner(source, context, destFunc);
            }

            if(_typeMap.PreserveReferences)
            {
                var cache = Variable(_typeMap.DestinationTypeToUse, "cachedDestination");

                var condition = Condition(
                    AndAlso(
                        NotEqual(_source, Constant(null)),
                        Call(Property(_context, "InstanceCache"), typeof(Dictionary<object, object>).GetDeclaredMethod("ContainsKey"), _source)),
                    Assign(cache,
                        ToType(Property(Property(_context, "InstanceCache"), "Item", _source), _typeMap.DestinationTypeToUse)),
                    Assign(cache, mapperFunc)
                    );

                mapperFunc = Block(new[] { cache }, condition, cache);
            }
            return mapperFunc;
        }