Add project files.

Compat.Private.Serialization/Compat/Runtime/Serialization/HybridObjectCache.cs

@@ -0,0 +1,70 @@
+using System.Collections.Generic;
+
+namespace Compat.Runtime.Serialization
+{
+    internal class HybridObjectCache
+    {
+        private Dictionary<string, object> _objectDictionary;
+        private Dictionary<string, object> _referencedObjectDictionary;
+
+        internal HybridObjectCache()
+        {
+        }
+
+        internal void Add(string id, object obj)
+        {
+            if (_objectDictionary == null)
+            {
+                _objectDictionary = new Dictionary<string, object>();
+            }
+
+            if (_objectDictionary.TryGetValue(id, out object existingObject))
+            {
+                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(XmlObjectSerializer.CreateSerializationException(SR.Format(SR.MultipleIdDefinition, id)));
+            }
+
+            _objectDictionary.Add(id, obj);
+        }
+
+        internal void Remove(string id)
+        {
+            if (_objectDictionary != null)
+            {
+                _objectDictionary.Remove(id);
+            }
+        }
+
+        internal object GetObject(string id)
+        {
+            if (_referencedObjectDictionary == null)
+            {
+                _referencedObjectDictionary = new Dictionary<string, object>
+                {
+                    { id, null }
+                };
+            }
+            else if (!_referencedObjectDictionary.ContainsKey(id))
+            {
+                _referencedObjectDictionary.Add(id, null);
+            }
+
+            if (_objectDictionary != null)
+            {
+                _objectDictionary.TryGetValue(id, out object obj);
+                return obj;
+            }
+
+            return null;
+        }
+
+        internal bool IsObjectReferenced(string id)
+        {
+            if (_referencedObjectDictionary != null)
+            {
+                return _referencedObjectDictionary.ContainsKey(id);
+            }
+            return false;
+        }
+
+    }
+}