Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Web/UI/WebControls/ReadOnlyDataSource.cs

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+//------------------------------------------------------------------------------
+// <copyright file="ReadOnlyDataSource.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>
+//------------------------------------------------------------------------------
+
+namespace System.Web.UI.WebControls {
+
+    using System;
+    using System.Collections;
+    using System.ComponentModel;
+    using System.Web;
+    using System.Web.UI;
+    using System.Web.Util;
+
+
+    /// <devdoc>
+    /// Helper class for data bound controls to wrap an generic data source
+    /// with a strongly typed IDataSource. This class automatically handles
+    /// other IDataSources, IEnumerable, and IListSource objects.
+    /// This class uses ReadOnlyDataSourceView to represent individual views.
+    /// </devdoc>
+    internal sealed class ReadOnlyDataSource : IDataSource {
+
+        private static string[] ViewNames = new string[0];
+
+        private string _dataMember;
+        private object _dataSource;
+
+        public ReadOnlyDataSource(object dataSource, string dataMember) {
+            Debug.Assert(dataSource == null || (dataSource is IEnumerable || dataSource is IDataSource || dataSource is IListSource), "Expected dataSource to be either null, an IEnumerable, an IDataSource, or an IListSource.");
+            _dataSource = dataSource;
+            _dataMember = dataMember;
+        }
+
+        #region Implementation of IDataSource
+        event EventHandler IDataSource.DataSourceChanged {
+            add {
+            }
+            remove {
+            }
+        }
+
+        /// <devdoc>
+        /// Check for IDataSource, IListSource, and IEnumerable, and return an
+        /// approprite DataSourceView.
+        /// </devdoc>
+        DataSourceView IDataSource.GetView(string viewName) {
+            // Check first for IDataSource
+            IDataSource ds = _dataSource as IDataSource;
+            if (ds != null) {
+                return ds.GetView(viewName);
+            }
+
+            IEnumerable enumerable = DataSourceHelper.GetResolvedDataSource(_dataSource, _dataMember);
+            return new ReadOnlyDataSourceView(this, _dataMember, enumerable);
+        }
+
+        ICollection IDataSource.GetViewNames() {
+            return ViewNames;
+        }
+        #endregion
+    }
+}
+