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

   1 //------------------------------------------------------------------------------
   2 // <copyright file="VariableQuery.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     using System.Xml.Xsl;
  15
  16     internal sealed class VariableQuery : ExtensionQuery {
  17         private IXsltContextVariable variable;
  18
  19         public VariableQuery(string name, string prefix) : base(prefix, name) {}
  20         private VariableQuery(VariableQuery other) : base(other) {
  21             this.variable = other.variable;
  22         }
  23
  24         public override void SetXsltContext(XsltContext context) {
  25             if (context == null) {
  26                 throw XPathException.Create(Res.Xp_NoContext);
  27             }
  28
  29                         if (this.xsltContext != context) {
  30                 xsltContext = context;
  31                                 variable = xsltContext.ResolveVariable(prefix, name);
  32                 // Since null is allowed for ResolveFunction, allow it for ResolveVariable as well
  33                 if (variable == null) {
  34                     throw XPathException.Create(Res.Xp_UndefVar, QName);
  35                 }
  36             }
  37         }
  38
  39         public override object Evaluate(XPathNodeIterator nodeIterator) {
  40                         if (xsltContext == null) {
  41                                 throw XPathException.Create(Res.Xp_NoContext);
  42                         }
  43
  44             return ProcessResult(variable.Evaluate(xsltContext));
  45         }
  46
  47         public override XPathResultType StaticType { get {
  48             if (variable != null) {  // Temp. fix to overcome dependency on static type
  49                 return GetXPathType(Evaluate(null));
  50             }
  51             XPathResultType result = variable != null ? variable.VariableType : XPathResultType.Any;
  52                         if (result == XPathResultType.Error) {
  53                                 // In v.1 we confused Error & Any so now for backward compatibility we should allow users to return any of them.
  54                                 result = XPathResultType.Any;
  55                         }
  56             return result;
  57         } }
  58
  59         public override XPathNodeIterator Clone() { return new VariableQuery(this); }
  60
  61         public override void PrintQuery(XmlWriter w) {
  62             w.WriteStartElement(this.GetType().Name);
  63             w.WriteAttributeString("name", prefix.Length != 0 ? prefix + ':' + name : name);
  64             w.WriteEndElement();
  65         }
  66     }
  67 }