System.Xml.Serialization.XmlCodeExporter.AddDefaultValueAttribute C# (CSharp) Method

        void AddDefaultValueAttribute(CodeMemberField field, CodeAttributeDeclarationCollection metadata, object defaultValue, TypeMapping mapping, CodeCommentStatementCollection comments, TypeDesc memberTypeDesc, Accessor accessor, CodeConstructor ctor) {
            string attributeName = accessor.IsFixed ? "fixed" : "default";
            if (!memberTypeDesc.HasDefaultSupport) {
                if (comments != null && defaultValue is string) {
                    DropDefaultAttribute(accessor, comments, memberTypeDesc.FullName);
                    // do not generate intializers for the user prefered types if they do not have default capability
                    AddWarningComment(comments, Res.GetString(Res.XmlDropAttributeValue, attributeName, mapping.TypeName, defaultValue.ToString()));
                }
                return;
            }
            if (memberTypeDesc.IsArrayLike && accessor is ElementAccessor) {
                if (comments != null && defaultValue is string) {
                    DropDefaultAttribute(accessor, comments, memberTypeDesc.FullName);
                    // do not generate intializers for array-like types
                    AddWarningComment(comments, Res.GetString(Res.XmlDropArrayAttributeValue, attributeName, defaultValue.ToString(), ((ElementAccessor)accessor).Name));
                }
                return;
            }
            if (mapping.TypeDesc.IsMappedType && field != null && defaultValue is string) {
                SchemaImporterExtension extension = mapping.TypeDesc.ExtendedType.Extension;
                CodeExpression init = extension.ImportDefaultValue((string)defaultValue, mapping.TypeDesc.FullName);

                if (init != null) {
                    if (ctor != null) {
                        AddInitializationStatement(ctor, field, init);
                    }
                    else {
                        field.InitExpression = extension.ImportDefaultValue((string)defaultValue, mapping.TypeDesc.FullName);
                    }
                }
                if (comments != null) {
                    DropDefaultAttribute(accessor, comments, mapping.TypeDesc.FullName);
                    if (init == null) {
                        AddWarningComment(comments, Res.GetString(Res.XmlNotKnownDefaultValue, extension.GetType().FullName, attributeName, (string)defaultValue, mapping.TypeName, mapping.Namespace));
                    }
                }
                return;
            }
            object value = null;
            if (defaultValue is string || defaultValue == null) {
                value = ImportDefault(mapping, (string)defaultValue);
            }
            if (value == null) return;
            if (!(mapping is PrimitiveMapping)) {
                DropDefaultAttribute(accessor, comments, memberTypeDesc.FullName);
                AddWarningComment(comments, Res.GetString(Res.XmlDropNonPrimitiveAttributeValue, attributeName, defaultValue.ToString()));
                return;
            }
            PrimitiveMapping pm = (PrimitiveMapping)mapping;

            if (comments != null && !pm.TypeDesc.HasDefaultSupport && pm.TypeDesc.IsMappedType) {
                // do not generate intializers for the user prefered types if they do not have default capability
                DropDefaultAttribute(accessor, comments, pm.TypeDesc.FullName);
                return;
            }
            if (value == DBNull.Value) {
                if (comments != null) {
                    AddWarningComment(comments, Res.GetString(Res.XmlDropAttributeValue, attributeName, pm.TypeName, defaultValue.ToString()));
                }
                return;
            }
            CodeAttributeArgument[] arguments = null;
            CodeExpression initExpression = null;
            
            if (pm.IsList) {
                #if DEBUG
                    // use exception in the place of Debug.Assert to avoid throwing asserts from a server process such as aspnet_ewp.exe
                    if (value.GetType() != typeof(object[])) throw new InvalidOperationException(Res.GetString(Res.XmlInternalErrorDetails, "Default value for list should be object[], not " + value.GetType().Name));
                #endif

                object[] vals = (object[])value;
                CodeExpression[] initializers = new CodeExpression[vals.Length];
                for (int i = 0; i < vals.Length; i++) {
                    GetDefaultValueArguments(pm, vals[i], out initializers[i]);
                }
                initExpression = new CodeArrayCreateExpression(field.Type, initializers);
                
            }
            else {
                arguments = GetDefaultValueArguments(pm, value, out initExpression);
            }

            if (field != null) {
                if (ctor != null) {
                    AddInitializationStatement(ctor, field, initExpression);
                }
                else {
                    field.InitExpression = initExpression;
                }
            }
            if (arguments != null && pm.TypeDesc.HasDefaultSupport && accessor.IsOptional && !accessor.IsFixed) {
                // Add [DefaultValueAttribute]
                CodeAttributeDeclaration attribute = new CodeAttributeDeclaration(typeof(DefaultValueAttribute).FullName, arguments);
                metadata.Add(attribute);
            }
            else if (comments != null) {
                DropDefaultAttribute(accessor, comments, memberTypeDesc.FullName);
            }
        }