Imported Upstream version 4.0.0~alpha1

Former-commit-id: 806294f5ded97629b74c85c09952f2a74fe182d9

external/referencesource/System.Xml/System/Xml/XPath/XPathNavigatorKeyComparer.cs

@@ -0,0 +1,55 @@
+//------------------------------------------------------------------------------
+// <copyright file="XmlNavigatorReader.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>
+// <owner current="true" primary="true">[....]</owner>
+//------------------------------------------------------------------------------
+
+using System.IO;
+using System.Xml.Schema;
+using System.Collections;
+using System.Diagnostics;
+using MS.Internal.Xml.Cache;
+
+namespace System.Xml.XPath {
+    internal class XPathNavigatorKeyComparer : IEqualityComparer {
+        bool IEqualityComparer.Equals( Object obj1, Object obj2 ) {
+            XPathNavigator nav1 = obj1 as XPathNavigator;
+            XPathNavigator nav2 = obj2 as XPathNavigator;
+            if( ( nav1 != null ) && ( nav2 != null ) ) {
+                if( nav1.IsSamePosition( nav2 ) )
+                    return true;
+            }
+            return false;
+        }
+
+        int IEqualityComparer.GetHashCode ( Object obj ) {
+            int hashCode;
+            XPathNavigator nav;
+            XPathDocumentNavigator xpdocNav;
+
+            if (obj == null) {
+                throw new ArgumentNullException("obj");
+            }
+            else if ( null != (xpdocNav = obj as XPathDocumentNavigator) ) {
+                hashCode = xpdocNav.GetPositionHashCode();
+            }
+            else if( null != (nav = obj as XPathNavigator) ) {
+                Object underlyingObject = nav.UnderlyingObject;
+                if (underlyingObject != null) {
+                    hashCode = underlyingObject.GetHashCode();
+                }
+                else {
+                    hashCode = (int)nav.NodeType;
+                    hashCode ^= nav.LocalName.GetHashCode();
+                    hashCode ^= nav.Prefix.GetHashCode();
+                    hashCode ^= nav.NamespaceURI.GetHashCode();
+                }
+            } 
+            else {
+                hashCode = obj.GetHashCode();
+            }
+            return hashCode;
+        }
+    }
+}