Object Explorer Service (#311)

* moving OE service from an old branch

src/Microsoft.SqlTools.ServiceLayer/ObjectExplorer/SmoModel/FolderNode.cs

@@ -0,0 +1,33 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using Microsoft.SqlServer.Management.Smo;
+
+namespace Microsoft.SqlTools.ServiceLayer.ObjectExplorer.SmoModel
+{
+    /// <summary>
+    /// Represents a folder node in the tree
+    /// </summary>
+    public class FolderNode : SmoTreeNode
+    {
+        /// <summary>
+        /// For folders, this copies the context of its parent if available
+        /// </summary>
+        /// <returns></returns>
+        public override object GetContext()
+        {
+            return Parent?.GetContext();
+        }
+
+        /// <summary>
+        /// For folders, searches for its parent's SMO object rather than copying for itself
+        /// </summary>
+        /// <returns><see cref="NamedSmoObject"/> from this parent's parent, or null if not found</returns>
+        public override NamedSmoObject GetParentSmoObject()
+        {
+            return ParentAs<SmoTreeNode>()?.GetParentSmoObject();
+        }
+    }
+}