1 files changed, 109 insertions, 0 deletions
diff --git a/Xamarin.Forms.Core/DefinitionCollection.cs b/Xamarin.Forms.Core/DefinitionCollection.cs
new file mode 100644
index 00000000..bf0e4d06
--- /dev/null
+++ b/Xamarin.Forms.Core/DefinitionCollection.cs
@@ -0,0 +1,109 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+
+namespace Xamarin.Forms
+{
+	public class DefinitionCollection<T> : IList<T>, ICollection<T> where T : IDefinition
+	{
+		readonly List<T> _internalList = new List<T>();
+
+		internal DefinitionCollection()
+		{
+		}
+
+		public void Add(T item)
+		{
+			_internalList.Add(item);
+			item.SizeChanged += OnItemSizeChanged;
+			OnItemSizeChanged(this, EventArgs.Empty);
+		}
+
+		public void Clear()
+		{
+			foreach (T item in _internalList)
+				item.SizeChanged -= OnItemSizeChanged;
+			_internalList.Clear();
+			OnItemSizeChanged(this, EventArgs.Empty);
+		}
+
+		public bool Contains(T item)
+		{
+			return _internalList.Contains(item);
+		}
+
+		public void CopyTo(T[] array, int arrayIndex)
+		{
+			_internalList.CopyTo(array, arrayIndex);
+		}
+
+		public int Count
+		{
+			get { return _internalList.Count; }
+		}
+
+		public bool IsReadOnly
+		{
+			get { return false; }
+		}
+
+		public bool Remove(T item)
+		{
+			item.SizeChanged -= OnItemSizeChanged;
+			bool success = _internalList.Remove(item);
+			if (success)
+				OnItemSizeChanged(this, EventArgs.Empty);
+			return success;
+		}
+
+		IEnumerator IEnumerable.GetEnumerator()
+		{
+			return _internalList.GetEnumerator();
+		}
+
+		public IEnumerator<T> GetEnumerator()
+		{
+			return _internalList.GetEnumerator();
+		}
+
+		public int IndexOf(T item)
+		{
+			return _internalList.IndexOf(item);
+		}
+
+		public void Insert(int index, T item)
+		{
+			_internalList.Insert(index, item);
+			item.SizeChanged += OnItemSizeChanged;
+			OnItemSizeChanged(this, EventArgs.Empty);
+		}
+
+		public T this[int index]
+		{
+			get { return _internalList[index]; }
+			set
+			{
+				_internalList[index] = value;
+				value.SizeChanged += OnItemSizeChanged;
+				OnItemSizeChanged(this, EventArgs.Empty);
+			}
+		}
+
+		public void RemoveAt(int index)
+		{
+			T item = _internalList[index];
+			_internalList.RemoveAt(index);
+			item.SizeChanged -= OnItemSizeChanged;
+			OnItemSizeChanged(this, EventArgs.Empty);
+		}
+
+		public event EventHandler ItemSizeChanged;
+
+		void OnItemSizeChanged(object sender, EventArgs e)
+		{
+			EventHandler eh = ItemSizeChanged;
+			if (eh != null)
+				eh(this, EventArgs.Empty);
+		}
+	}
+}
+\ No newline at end of file