System.Xml.Xsl.XmlQueryTypeFactory.DescendantsOf C# (CSharp) Method

        public XmlQueryType DescendantsOf(XmlQueryType source, XmlQueryType filter) {
            Debug.Assert(filter.IsNode && filter.Count == 1 && filter.IsSingleton);
            List<XmlQueryType> list = new List<XmlQueryType>();
            XmlQueryCardinality card = XmlQueryCardinality.None;

            foreach (XmlQueryType sourceItem  in source) {
                switch (sourceItem.TypeCode) {
                case XmlTypeCode.Node:
                case XmlTypeCode.Document:
                case XmlTypeCode.Element:
                    XmlQueryCardinality itemCard = XmlQueryCardinality.None;
                    if ((filter.NodeKinds & (XmlNodeKindFlags.Element | XmlNodeKindFlags.Text)) != 0) {
                        Dictionary<XmlQualifiedName, XmlQueryCardinality> allTypes = new Dictionary<XmlQualifiedName, XmlQueryCardinality>();
                        XmlSchemaType sourceSchemaType = sourceItem.SchemaType;
                        if (sourceSchemaType == null) {
                            Debug.Assert(sourceItem.TypeCode == XmlTypeCode.Node);
                            sourceSchemaType = XmlSchemaComplexType.AnyType;
                        }
                        itemCard = AddElementOrTextDescendants(list, allTypes, sourceSchemaType, filter);
                    }
                    itemCard += AddFilteredPrime(list, PI, filter);
                    itemCard += AddFilteredPrime(list, Comment, filter);
                    card |= itemCard;
                    break;

                case XmlTypeCode.Attribute:
                case XmlTypeCode.ProcessingInstruction:
                case XmlTypeCode.Comment:
                case XmlTypeCode.Namespace:
                case XmlTypeCode.Text:
                    card |= XmlQueryCardinality.Zero;
                    break;

                default:
                    Debug.Assert(sourceItem.IsAtomicValue, "missed case for a node");
                        break;
                }
            }
            // Make sure that cardinality is at least Zero
            return PrimeProduct(ChoiceType.Create(list), source.Cardinality * card);
        }