System.Xml.Serialization.SerializableMapping.RetrieveSerializableSchema C# (CSharp) Method

        private void RetrieveSerializableSchema()
        {
            if (_needSchema)
            {
                _needSchema = false;
                if (_getSchemaMethod != null)
                {
                    // get the type info
                    if (_schemas == null)
                        _schemas = new XmlSchemaSet();
                    object typeInfo = _getSchemaMethod.Invoke(null, new object[] { _schemas });
                    _xsiType = XmlQualifiedName.Empty;

                    if (typeInfo != null)
                    {
                        if (typeof(XmlSchemaType).IsAssignableFrom(_getSchemaMethod.ReturnType))
                        {
                            _xsdType = (XmlSchemaType)typeInfo;
                            // check if type is named
                            _xsiType = _xsdType.QualifiedName;
                        }
                        else if (typeof(XmlQualifiedName).IsAssignableFrom(_getSchemaMethod.ReturnType))
                        {
                            _xsiType = (XmlQualifiedName)typeInfo;
                            if (_xsiType.IsEmpty)
                            {
                                throw new InvalidOperationException(SR.Format(SR.XmlGetSchemaEmptyTypeName, _type.FullName, _getSchemaMethod.Name));
                            }
                        }
                        else
                        {
                            throw new InvalidOperationException(SR.Format(SR.XmlGetSchemaMethodReturnType, _type.Name, _getSchemaMethod.Name, typeof(XmlSchemaProviderAttribute).Name, typeof(XmlQualifiedName).FullName));
                        }
                    }
                    else
                    {
                        _any = true;
                    }

                    // make sure that user-specified schemas are valid
                    _schemas.ValidationEventHandler += new ValidationEventHandler(ValidationCallbackWithErrorCode);
                    _schemas.Compile();
                    // at this point we verified that the information returned by the IXmlSerializable is valid
                    // Now check to see if the type was referenced before:
                    // UNDONE check for the duplcate types
                    if (!_xsiType.IsEmpty)
                    {
                        // try to find the type in the schemas collection
                        if (_xsiType.Namespace != XmlSchema.Namespace)
                        {
                            ArrayList srcSchemas = (ArrayList)_schemas.Schemas(_xsiType.Namespace);

                            if (srcSchemas.Count == 0)
                            {
                                throw new InvalidOperationException(SR.Format(SR.XmlMissingSchema, _xsiType.Namespace));
                            }
                            if (srcSchemas.Count > 1)
                            {
                                throw new InvalidOperationException(SR.Format(SR.XmlGetSchemaInclude, _xsiType.Namespace, _getSchemaMethod.DeclaringType.FullName, _getSchemaMethod.Name));
                            }
                            XmlSchema s = (XmlSchema)srcSchemas[0];
                            if (s == null)
                            {
                                throw new InvalidOperationException(SR.Format(SR.XmlMissingSchema, _xsiType.Namespace));
                            }
                            _xsdType = (XmlSchemaType)s.SchemaTypes[_xsiType];
                            if (_xsdType == null)
                            {
                                throw new InvalidOperationException(SR.Format(SR.XmlGetSchemaTypeMissing, _getSchemaMethod.DeclaringType.FullName, _getSchemaMethod.Name, _xsiType.Name, _xsiType.Namespace));
                            }
                            _xsdType = _xsdType.Redefined != null ? _xsdType.Redefined : _xsdType;
                        }
                    }
                }
                else
                {
                    IXmlSerializable serializable = (IXmlSerializable)Activator.CreateInstance(_type);
                    _schema = serializable.GetSchema();

                    if (_schema != null)
                    {
                        if (_schema.Id == null || _schema.Id.Length == 0) throw new InvalidOperationException(SR.Format(SR.XmlSerializableNameMissing1, _type.FullName));
                    }
                }
            }
        }
    }