port from perforce

intromat/Intromat/PersistentModel/NodeCollectionModel.cs

@@ -0,0 +1,74 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
+using System.Xml;
+using System.Xml.Schema;
+using System.Xml.Serialization;
+
+namespace Intromat.PersistentModel
+{
+    public class NodeCollectionModel : IXmlSerializable
+    {
+        public static readonly Dictionary<string, Type> _nodeTypes;
+        public static readonly XmlSerializerNamespaces _nameSpaces;
+
+        static NodeCollectionModel()
+        {
+            _nodeTypes = typeof(NodeModelBase)
+                .Assembly
+                .GetTypes()
+                .Where(t => typeof(NodeModelBase).IsAssignableFrom(t) && !t.IsAbstract)
+                .Select(type =>
+                {
+                    var attrib = (XmlRootAttribute)type.GetCustomAttribute(typeof(XmlRootAttribute))!;
+                    return (attrib.ElementName, Type: type);
+                })
+                .ToDictionary(pair => pair.ElementName, pair => pair.Type);
+            
+            _nameSpaces = new XmlSerializerNamespaces();
+            _nameSpaces.Add(string.Empty, NodeModelBase._namespace);
+            _nameSpaces.Add("x", "http://www.w3.org/2001/XMLSchema-instance");
+        }
+
+        public List<NodeModelBase> Items { get; set; } = new();
+
+        public XmlSchema? GetSchema()
+        {
+            return null;
+        }
+
+        public void ReadXml(XmlReader reader)
+        {
+            reader.MoveToContent();
+            var isEmptyElement = reader.IsEmptyElement;
+            reader.ReadStartElement();
+            if (!isEmptyElement)
+            {
+                while (reader.NodeType != XmlNodeType.EndElement)
+                {
+                    if (_nodeTypes.TryGetValue(reader.Name, out var nodeType))
+                    {
+                        var serializer = new XmlSerializer(nodeType);
+                        var node = (NodeModelBase)serializer.Deserialize(reader)!;
+                        Items.Add(node);
+                    }
+                }
+
+                reader.ReadEndElement();
+            }
+        }
+
+        public void WriteXml(XmlWriter writer)
+        {
+            if (Items.Count == 0)
+                return;
+            
+            foreach (var node in Items)
+            {
+                var serializer = new XmlSerializer(node.GetType());
+                serializer.Serialize(writer, node, _nameSpaces);
+            }
+        }
+    }
+}