System.Xml.Serialization.XmlReflectionImporter.ImportSpecialMapping C# (CSharp) Method

        private SpecialMapping ImportSpecialMapping(Type type, TypeDesc typeDesc, string ns, ImportContext context, RecursionLimiter limiter)
        {
            if (_specials == null)
                _specials = new Hashtable();
            SpecialMapping mapping = (SpecialMapping)_specials[type];
            if (mapping != null)
            {
                CheckContext(mapping.TypeDesc, context);
                return mapping;
            }
            if (typeDesc.Kind == TypeKind.Serializable)
            {
                SerializableMapping serializableMapping = null;

                // get the schema method info
                object[] attrs = type.GetCustomAttributes(typeof(XmlSchemaProviderAttribute), false);

                if (attrs.Length > 0)
                {
                    // new IXmlSerializable
                    XmlSchemaProviderAttribute provider = (XmlSchemaProviderAttribute)attrs[0];
                    MethodInfo method = GetMethodFromSchemaProvider(provider, type);
                    serializableMapping = new SerializableMapping(method, provider.IsAny, ns);
                    XmlQualifiedName qname = serializableMapping.XsiType;
                    if (qname != null && !qname.IsEmpty)
                    {
                        if (_serializables == null)
                            _serializables = new NameTable();
                        SerializableMapping existingMapping = (SerializableMapping)_serializables[qname];
                        if (existingMapping != null)
                        {
                            if (existingMapping.Type == null)
                            {
                                serializableMapping = existingMapping;
                            }
                            else if (existingMapping.Type != type)
                            {
                                SerializableMapping next = existingMapping.Next;
                                existingMapping.Next = serializableMapping;
                                serializableMapping.Next = next;
                            }
                        }
                        else
                        {
                            XmlSchemaType xsdType = serializableMapping.XsdType;
                            if (xsdType != null)
                                SetBase(serializableMapping, xsdType.DerivedFrom);
                            _serializables[qname] = serializableMapping;
                        }
                        serializableMapping.TypeName = qname.Name;
                        serializableMapping.Namespace = qname.Namespace;
                    }
                    serializableMapping.TypeDesc = typeDesc;
                    serializableMapping.Type = type;
                    IncludeTypes(type.GetTypeInfo());
                }
                else
                {
                    // old IXmlSerializable
                    serializableMapping = new SerializableMapping();
                    serializableMapping.TypeDesc = typeDesc;
                    serializableMapping.Type = type;
                }
                mapping = serializableMapping;
            }
            else
            {
                mapping = new SpecialMapping();
                mapping.TypeDesc = typeDesc;
            }
            CheckContext(typeDesc, context);
            _specials.Add(type, mapping);
            _typeScope.AddTypeMapping(mapping);
            return mapping;
        }