Add project files.

Compat.Private.Serialization/Compat/Runtime/Serialization/ObjectReferenceStack.cs

@@ -0,0 +1,114 @@
+using System;
+using System.Collections.Generic;
+
+namespace Compat.Runtime.Serialization
+{
+    internal struct ObjectReferenceStack
+    {
+        private const int MaximumArraySize = 16;
+        private const int InitialArraySize = 4;
+        private int count;
+        private object[] objectArray;
+        private bool[] isReferenceArray;
+        private Dictionary<object, object> objectDictionary;
+
+        internal void Push(object obj)
+        {
+            if (objectArray == null)
+            {
+                objectArray = new object[InitialArraySize];
+                objectArray[count++] = obj;
+            }
+            else if (count < MaximumArraySize)
+            {
+                if (count == objectArray.Length)
+                {
+                    Array.Resize<object>(ref objectArray, objectArray.Length * 2);
+                }
+
+                objectArray[count++] = obj;
+            }
+            else
+            {
+                if (objectDictionary == null)
+                {
+                    objectDictionary = new Dictionary<object, object>();
+                }
+
+                objectDictionary.Add(obj, null);
+                count++;
+            }
+        }
+
+        internal void EnsureSetAsIsReference(object obj)
+        {
+            if (count == 0)
+            {
+                return;
+            }
+
+            if (count > MaximumArraySize)
+            {
+                if (objectDictionary == null)
+                {
+                    Fx.Assert("Object reference stack in invalid state");
+                }
+                objectDictionary.Remove(obj);
+            }
+            else
+            {
+                if ((objectArray != null) && objectArray[count - 1] == obj)
+                {
+                    if (isReferenceArray == null)
+                    {
+                        isReferenceArray = new bool[objectArray.Length];
+                    }
+                    else if (count >= isReferenceArray.Length)
+                    {
+
+                        Array.Resize<bool>(ref isReferenceArray, objectArray.Length);
+                    }
+                    isReferenceArray[count - 1] = true;
+                }
+            }
+        }
+
+        internal void Pop(object obj)
+        {
+            if (count > MaximumArraySize)
+            {
+                if (objectDictionary == null)
+                {
+                    Fx.Assert("Object reference stack in invalid state");
+                }
+                objectDictionary.Remove(obj);
+            }
+            count--;
+        }
+
+        internal bool Contains(object obj)
+        {
+            int currentCount = count;
+            if (currentCount > MaximumArraySize)
+            {
+                if (objectDictionary != null && objectDictionary.ContainsKey(obj))
+                {
+                    return true;
+                }
+
+                currentCount = MaximumArraySize;
+            }
+            for (int i = (currentCount - 1); i >= 0; i--)
+            {
+                if (Object.ReferenceEquals(obj, objectArray[i]) && isReferenceArray != null && !isReferenceArray[i])
+                {
+                    return true;
+                }
+            }
+            return false;
+        }
+
+        internal int Count => count;
+
+    }
+}