Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Xml/System/Xml/Schema/SchemaNamespacemanager.cs

@@ -0,0 +1,55 @@
+//------------------------------------------------------------------------------
+// <copyright file="SchemaNamespaceManager.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>
+// <owner current="true" primary="true">[....]</owner>                                                                
+//------------------------------------------------------------------------------
+
+namespace System.Xml.Schema {
+    using System;
+    using System.Diagnostics;
+    using System.Collections;
+
+    internal class SchemaNamespaceManager : XmlNamespaceManager {
+        XmlSchemaObject node;
+    
+        public SchemaNamespaceManager(XmlSchemaObject node) {
+            this.node = node;
+        }
+        
+        public override string LookupNamespace(string prefix) {
+            if (prefix == "xml") { //Special case for the XML namespace
+                return XmlReservedNs.NsXml;
+            }
+            Hashtable namespaces;
+            for (XmlSchemaObject current = node; current != null; current = current.Parent) {
+                namespaces = current.Namespaces.Namespaces;
+                if (namespaces != null && namespaces.Count > 0) {
+                    object uri = namespaces[prefix];
+                    if (uri != null)
+                        return (string)uri;
+                }
+            }
+            return prefix.Length == 0 ? string.Empty : null;
+        }
+
+        public override string LookupPrefix(string ns) {
+            if (ns == XmlReservedNs.NsXml) { //Special case for the XML namespace
+                return "xml";
+            }
+            Hashtable namespaces;
+            for (XmlSchemaObject current = node; current != null; current = current.Parent) {
+                namespaces = current.Namespaces.Namespaces;
+                if (namespaces != null && namespaces.Count > 0) {
+                    foreach(DictionaryEntry entry in namespaces) {
+                        if (entry.Value.Equals(ns)) {
+                            return (string)entry.Key;
+                        }
+                    }
+                }
+            }
+            return null;
+        }
+
+  }; //SchemaNamespaceManager
+}