Object Explorer Service (#311)

* moving OE service from an old branch

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

@@ -0,0 +1,57 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using Microsoft.SqlServer.Management.Smo;
+
+namespace Microsoft.SqlTools.ServiceLayer.ObjectExplorer.SmoModel
+{
+    /// <summary>
+    /// Wrapper to convert non-generic Smo enumerables to generic enumerable types for easier use in 
+    /// </summary>
+    /// <typeparam name="T"></typeparam>
+    public class SmoCollectionWrapper<T> : IEnumerable<T>
+        where T : SqlSmoObject
+    {
+        private SmoCollectionBase collection;
+
+        /// <summary>
+        /// Constructor which accepts a <see cref="SmoCollectionBase"/> containing the objects
+        /// to wrap 
+        /// </summary>
+        /// <param name="collection"><see cref="SmoCollectionBase"/> or null if none were set</param>
+        public SmoCollectionWrapper(SmoCollectionBase collection)
+        {
+            this.collection = collection;
+        }
+
+        /// <summary>
+        /// <see cref="IEnumerable{T}.GetEnumerator"/>
+        /// </summary>
+        /// <returns></returns>
+        public IEnumerator<T> GetEnumerator()
+        {
+            if (collection == null)
+            {
+                yield break;
+            }
+            foreach(Object obj in collection)
+            {
+                yield return (T)obj;
+            }
+        }
+
+        /// <summary>
+        /// <see cref="IEnumerable.GetEnumerator"/>
+        /// </summary>
+        /// <returns></returns>
+        IEnumerator IEnumerable.GetEnumerator()
+        {
+            return collection?.GetEnumerator();
+        }
+    }
+}