Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

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

@@ -0,0 +1,53 @@
+namespace System.Web.UI.WebControls.Expressions {
+    using System;
+    using System.Collections.ObjectModel;
+    using System.ComponentModel;
+    using System.Diagnostics.CodeAnalysis;
+    using System.Linq;
+    using System.Linq.Expressions;
+    using System.Web;
+    using System.Web.UI;
+
+    [
+    ParseChildren(true, "Expressions"),
+    PersistChildren(false)
+    ]
+    public class QueryExpression {
+        private HttpContext _context;
+        private Control _owner;
+        private IQueryableDataSource _dataSource;
+        private DataSourceExpressionCollection _expressions;
+
+        [
+        PersistenceMode(PersistenceMode.InnerDefaultProperty)
+        ]
+        public DataSourceExpressionCollection Expressions {
+            get {
+                if (_expressions == null) {
+                    _expressions = new DataSourceExpressionCollection();
+                }
+                return _expressions;
+            }
+        }
+
+        public void Initialize(Control owner, HttpContext context, IQueryableDataSource dataSource) {
+            _owner = owner;
+            _context = context;
+            _dataSource = dataSource;
+
+            Expressions.SetContext(owner, context, dataSource);
+        }
+
+        public virtual IQueryable GetQueryable(IQueryable source) {
+            if (source == null) {
+                return null;
+            }
+
+            foreach (DataSourceExpression e in Expressions) {
+                source = e.GetQueryable(source) ?? source;
+            }
+
+            return source;
+        }
+    }
+}