Added OrderedSet utility class.

src/Generator/Utils/OrderedSet.cs

@@ -0,0 +1,85 @@
+using System.Collections;
+using System.Collections.Generic;
+
+namespace CppSharp.Utils
+{
+    /// <summary>
+    /// Works just like an HashSet but preserves insertion order.
+    /// </summary>
+    /// <typeparam name="T"></typeparam>
+    public class OrderedSet<T> : ICollection<T>
+    {
+        private readonly IDictionary<T, LinkedListNode<T>> dictionary;
+        private readonly LinkedList<T> linkedList;
+
+        public OrderedSet()
+            : this(EqualityComparer<T>.Default)
+        {
+        }
+
+        public OrderedSet(IEqualityComparer<T> comparer)
+        {
+            dictionary = new Dictionary<T, LinkedListNode<T>>(comparer);
+            linkedList = new LinkedList<T>();
+        }
+
+        public int Count
+        {
+            get { return dictionary.Count; }
+        }
+
+        public virtual bool IsReadOnly
+        {
+            get { return dictionary.IsReadOnly; }
+        }
+
+        void ICollection<T>.Add(T item)
+        {
+            Add(item);
+        }
+
+        public bool Add(T item)
+        {
+            if (dictionary.ContainsKey(item)) return false;
+            LinkedListNode<T> node = linkedList.AddLast(item);
+            dictionary.Add(item, node);
+            return true;
+        }
+
+        public void Clear()
+        {
+            linkedList.Clear();
+            dictionary.Clear();
+        }
+
+        public bool Remove(T item)
+        {
+            LinkedListNode<T> node;
+            bool found = dictionary.TryGetValue(item, out node);
+            if (!found) return false;
+            dictionary.Remove(item);
+            linkedList.Remove(node);
+            return true;
+        }
+
+        public IEnumerator<T> GetEnumerator()
+        {
+            return linkedList.GetEnumerator();
+        }
+
+        IEnumerator IEnumerable.GetEnumerator()
+        {
+            return GetEnumerator();
+        }
+
+        public bool Contains(T item)
+        {
+            return dictionary.ContainsKey(item);
+        }
+
+        public void CopyTo(T[] array, int arrayIndex)
+        {
+            linkedList.CopyTo(array, arrayIndex);
+        }
+    }
+}