FastMember.TypeAccessor.WriteMapImpl C# (CSharp) Метод

        private static void WriteMapImpl(ILGenerator il, Type type, List<MemberInfo> members, FieldBuilder mapField, bool allowNonPublicAccessors, bool isGet)
        {
            OpCode obj, index, value;

            Label fail = il.DefineLabel();
            if (mapField == null)
            {
                index = OpCodes.Ldarg_0;
                obj = OpCodes.Ldarg_1;
                value = OpCodes.Ldarg_2;
            }
            else
            {
                il.DeclareLocal(typeof(int));
                index = OpCodes.Ldloc_0;
                obj = OpCodes.Ldarg_1;
                value = OpCodes.Ldarg_3;

                il.Emit(OpCodes.Ldarg_0);
                il.Emit(OpCodes.Ldfld, mapField);
                il.Emit(OpCodes.Ldarg_2);
                il.Emit(OpCodes.Ldloca_S, (byte)0);
                il.EmitCall(OpCodes.Callvirt, tryGetValue, null);
                il.Emit(OpCodes.Brfalse, fail);
            }            
            Label[] labels = new Label[members.Count];
            for (int i = 0; i < labels.Length; i++)
            {
                labels[i] = il.DefineLabel();
            }
            il.Emit(index);
            il.Emit(OpCodes.Switch, labels);
            il.MarkLabel(fail);
            il.Emit(OpCodes.Ldstr, "name");
            il.Emit(OpCodes.Newobj, typeof(ArgumentOutOfRangeException).GetConstructor(new Type[] { typeof(string) }));
            il.Emit(OpCodes.Throw);
            for (int i = 0; i < labels.Length; i++)
            {
                il.MarkLabel(labels[i]);
                var member = members[i];
                bool isFail = true;
                FieldInfo field;
                PropertyInfo prop;
                if((field = member as FieldInfo) != null)
                {
                    il.Emit(obj);
                    Cast(il, type, true);
                    if (isGet)
                    {
                        il.Emit(OpCodes.Ldfld, field);
                        if (_IsValueType(field.FieldType)) il.Emit(OpCodes.Box, field.FieldType);
                    }
                    else
                    {
                        il.Emit(value);
                        Cast(il, field.FieldType, false);
                        il.Emit(OpCodes.Stfld, field);
                    }
                    il.Emit(OpCodes.Ret);
                    isFail = false;
                }
                else if ((prop = member as PropertyInfo) != null)
                {
                    MethodInfo accessor;
                    if (prop.CanRead && (accessor = isGet ? prop.GetGetMethod(allowNonPublicAccessors) : prop.GetSetMethod(allowNonPublicAccessors)) != null)
                    {
                        il.Emit(obj);
                        Cast(il, type, true);
                        if (isGet)
                        {
                            il.EmitCall(_IsValueType(type) ? OpCodes.Call : OpCodes.Callvirt, accessor, null);
                            if (_IsValueType(prop.PropertyType)) il.Emit(OpCodes.Box, prop.PropertyType);
                        }
                        else
                        {
                            il.Emit(value);
                            Cast(il, prop.PropertyType, false);
                            il.EmitCall(_IsValueType(type) ? OpCodes.Call : OpCodes.Callvirt, accessor, null);
                        }
                        il.Emit(OpCodes.Ret);
                        isFail = false;
                    }
                }
                if (isFail) il.Emit(OpCodes.Br, fail);
            }
        }