mcs/class/referencesource/System.Xml/System/Xml/XPath/Internal/NamespaceQuery.cs

   1 //------------------------------------------------------------------------------
   2 // <copyright file="NamespaceQuery.cs" company="Microsoft">
   3 //     Copyright (c) Microsoft Corporation.  All rights reserved.
   4 // </copyright>
   5 // <owner current="true" primary="true">Microsoft</owner>
   6 //------------------------------------------------------------------------------
   7
   8 namespace MS.Internal.Xml.XPath {
   9     using System;
  10     using System.Xml;
  11     using System.Xml.XPath;
  12     using System.Diagnostics;
  13     using System.Globalization;
  14
  15     internal sealed class NamespaceQuery : BaseAxisQuery {
  16         private bool onNamespace;
  17
  18         public NamespaceQuery(Query qyParent, string Name, string Prefix, XPathNodeType Type) : base(qyParent, Name, Prefix, Type) {}
  19         private NamespaceQuery(NamespaceQuery other) : base(other) {
  20             this.onNamespace = other.onNamespace;
  21         }
  22
  23         public override void Reset() {
  24             onNamespace = false;
  25             base.Reset();
  26         }
  27
  28         public override XPathNavigator Advance() {
  29             while (true) {
  30                 if (!onNamespace) {
  31                     currentNode = qyInput.Advance();
  32                     if (currentNode == null) {
  33                         return null;
  34                     }
  35                     position = 0;
  36                     currentNode = currentNode.Clone();
  37                     onNamespace = currentNode.MoveToFirstNamespace();
  38                 } else {
  39                     onNamespace = currentNode.MoveToNextNamespace();
  40                 }
  41
  42                 if (onNamespace) {
  43                     if (matches(currentNode)) {
  44                         position++;
  45                         return currentNode;
  46                     }
  47                 }
  48             } // while
  49         } // Advance
  50
  51         public override bool matches(XPathNavigator e) {
  52             Debug.Assert(e.NodeType == XPathNodeType.Namespace);
  53             if (e.Value.Length == 0) {
  54                 Debug.Assert(e.LocalName.Length == 0, "Only xmlns='' can have empty string as a value");
  55                 // Namespace axes never returns xmlns='',
  56                 // because it's not a NS declaration but rather undeclaration.
  57                 return false;
  58             }
  59             if (NameTest) {
  60                 return Name.Equals(e.LocalName);
  61             } else {
  62                 return true;
  63             }
  64         }
  65
  66         public override XPathNodeIterator Clone() { return new NamespaceQuery(this); }
  67     }
  68 }