Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Web.Extensions/ui/WebControls/Expressions/OrderByExpression.cs

@@ -0,0 +1,105 @@
+namespace System.Web.UI.WebControls.Expressions {    
+    using System;
+    using System.Collections.ObjectModel;
+    using System.Diagnostics;
+    using System.Linq;
+    using System.Linq.Expressions;
+    using System.Web.Resources;
+    using System.Web.UI;
+
+    [
+    PersistChildren(false),
+    ParseChildren(true, "ThenByExpressions")
+    ]
+    public class OrderByExpression : DataSourceExpression {
+        private const string OrderByMethod = "OrderBy";
+        private const string ThenByMethod = "ThenBy";
+        private const string OrderDescendingByMethod = "OrderByDescending";
+        private const string ThenDescendingByMethod = "ThenByDescending";
+
+        private Collection<ThenBy> _thenByExpressions;
+
+        public string DataField {
+            get {
+                return (string)ViewState["DataField"] ?? String.Empty;
+            }
+            set {
+                ViewState["DataField"] = value;
+            }
+        }
+
+        public SortDirection Direction {
+            get {
+                object o = ViewState["Direction"];
+                return o != null ? (SortDirection)o : SortDirection.Ascending;
+            }
+            set {
+                ViewState["Direction"] = value;
+            }
+        }
+
+        [PersistenceMode(PersistenceMode.InnerDefaultProperty)]
+        public Collection<ThenBy> ThenByExpressions {
+            get {
+                if (_thenByExpressions == null) {
+                    // 
+                    _thenByExpressions = new Collection<ThenBy>();
+                }
+                return _thenByExpressions;
+            }
+        }
+
+        public override IQueryable GetQueryable(IQueryable source) {
+            if (source == null) {
+                return null;
+            }
+
+            if (String.IsNullOrEmpty(DataField)) {
+                throw new InvalidOperationException(AtlasWeb.Expressions_DataFieldRequired);
+            }
+
+            ParameterExpression pe = Expression.Parameter(source.ElementType, String.Empty);
+            source = CreateSortQueryable(source, pe, Direction, DataField, false /* isThenBy */);
+
+            foreach (ThenBy thenBy in ThenByExpressions) {
+                source = CreateSortQueryable(source, pe, thenBy.Direction, thenBy.DataField, true /* isThenBy */);
+            }
+
+            return source;
+        }
+
+        private static IQueryable CreateSortQueryable(IQueryable source, ParameterExpression parameterExpression, SortDirection direction, string dataField, bool isThenBy) {
+            string methodName = isThenBy ? GetThenBySortMethod(direction) : GetSortMethod(direction);
+            Expression propertyExpression = ExpressionHelper.CreatePropertyExpression(parameterExpression, dataField);
+
+            return source.Call(methodName,
+                               Expression.Lambda(propertyExpression, parameterExpression),
+                               source.ElementType,
+                               propertyExpression.Type);
+        }
+
+        private static string GetSortMethod(SortDirection direction) {
+            switch (direction) {
+                case SortDirection.Ascending:
+                    return OrderByMethod;
+                case SortDirection.Descending:
+                    return OrderDescendingByMethod;
+                default:
+                    Debug.Fail("shouldn't get here!");
+                    return OrderByMethod;
+            }
+        }
+
+        private static string GetThenBySortMethod(SortDirection direction) {
+            switch (direction) {
+                case SortDirection.Ascending:
+                    return ThenByMethod;
+                case SortDirection.Descending:
+                    return ThenDescendingByMethod;
+                default:
+                    Debug.Fail("shouldn't get here!");
+                    return null;
+            }
+        }
+    }
+}