Merge branch 'master' of https://twinetfs.visualstudio.com/_git/Tango

1 files changed, 63 insertions, 0 deletions

diff --git a/Software/Visual_Studio/Scripting/Tango.Scripting.Editors/Utils/ObserveAddRemoveCollection.cs b/Software/Visual_Studio/Scripting/Tango.Scripting.Editors/Utils/ObserveAddRemoveCollection.cs
new file mode 100644
index 000000000..091de0d91
--- /dev/null
+++ b/Software/Visual_Studio/Scripting/Tango.Scripting.Editors/Utils/ObserveAddRemoveCollection.cs
@@ -0,0 +1,63 @@
+// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
+// This code is distributed under the GNU LGPL (for details please see \doc\license.txt)
+
+using System;
+using System.Collections.ObjectModel;
+
+namespace Tango.Scripting.Editors.Utils
+{
+	/// <summary>
+	/// A collection where adding and removing items causes a callback.
+	/// It is valid for the onAdd callback to throw an exception - this will prevent the new item from
+	/// being added to the collection.
+	/// </summary>
+	sealed class ObserveAddRemoveCollection<T> : Collection<T>
+	{
+		readonly Action<T> onAdd, onRemove;
+		
+		public ObserveAddRemoveCollection(Action<T> onAdd, Action<T> onRemove)
+		{
+			this.onAdd = onAdd;
+			this.onRemove = onRemove;
+		}
+		
+		protected override void ClearItems()
+		{
+			if (onRemove != null) {
+				foreach (T val in this)
+					onRemove(val);
+			}
+			base.ClearItems();
+		}
+		
+		protected override void InsertItem(int index, T item)
+		{
+			if (onAdd != null)
+				onAdd(item);
+			base.InsertItem(index, item);
+		}
+		
+		protected override void RemoveItem(int index)
+		{
+			if (onRemove != null)
+				onRemove(this[index]);
+			base.RemoveItem(index);
+		}
+		
+		protected override void SetItem(int index, T item)
+		{
+			if (onRemove != null)
+				onRemove(this[index]);
+			try {
+				if (onAdd != null)
+					onAdd(item);
+			} catch {
+				// When adding the new item fails, just remove the old one
+				// (we cannot keep the old item since we already successfully called onRemove for it)
+				base.RemoveAt(index);
+				throw;
+			}
+			base.SetItem(index, item);
+		}
+	}
+}