Imported Upstream version 4.0.0~alpha1

Former-commit-id: 806294f5ded97629b74c85c09952f2a74fe182d9

external/referencesource/System.Data/System/NewXml/BaseTreeIterator.cs

@@ -0,0 +1,49 @@
+//------------------------------------------------------------------------------
+// <copyright file="BaseTreeIterator.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>                                                                
+// <owner current="true" primary="true">[....]</owner>
+// <owner current="true" primary="false">[....]</owner>
+//------------------------------------------------------------------------------
+namespace System.Xml {
+
+    // Iterates over non-attribute nodes
+    internal abstract class BaseTreeIterator {
+        protected DataSetMapper   mapper;
+
+        internal BaseTreeIterator( DataSetMapper mapper ) {
+            this.mapper      = mapper;
+        }
+
+        internal abstract void Reset();
+
+        internal abstract XmlNode CurrentNode { get; }
+
+        internal abstract bool Next();
+        internal abstract bool NextRight();
+
+        internal bool NextRowElement() {
+            while ( Next() ) {
+                if ( OnRowElement() )
+                    return true;
+            }
+            return false;
+        }
+
+        internal bool NextRightRowElement() {
+            if ( NextRight() ) {
+                if ( OnRowElement() )
+                    return true;
+                return NextRowElement();
+            }
+            return false;
+        }
+
+        // Returns true if the current node is on a row element (head of a region)
+        internal bool OnRowElement() {
+            XmlBoundElement be = CurrentNode as XmlBoundElement;
+            return (be != null) && (be.Row != null);
+        }
+    }
+}
+