mcs/class/referencesource/System.Xml/System/Xml/Resolvers/XmlPreloadedResolverAsync.cs

   1 //------------------------------------------------------------------------------
   2 // <copyright file="XmlPreloadedResolver.cs" company="Microsoft">
   3 //     Copyright (c) Microsoft Corporation.  All rights reserved.
   4 // </copyright>
   5 // <owner current="true" primary="true">[....]</owner>
   6 //------------------------------------------------------------------------------
   7
   8 using System.IO;
   9 using System.Xml;
  10 using System.Threading.Tasks;
  11
  12 namespace System.Xml.Resolvers {
  13
  14     //
  15     // XmlPreloadedResolver is an XmlResolver that which can be pre-loaded with data.
  16     // By default it contains well-known DTDs for XHTML 1.0 and RSS 0.91.
  17     // Custom mappings of URIs to data can be added with the Add method.
  18     //
  19     public partial class XmlPreloadedResolver : XmlResolver {
  20
  21         public override Task<Object> GetEntityAsync(Uri absoluteUri,
  22                                              string role,
  23                                              Type ofObjectToReturn) {
  24
  25             if (absoluteUri == null) {
  26                 throw new ArgumentNullException("absoluteUri");
  27             }
  28
  29             PreloadedData data;
  30             if (!mappings.TryGetValue(absoluteUri, out data)) {
  31                 if (fallbackResolver != null) {
  32                     return fallbackResolver.GetEntityAsync(absoluteUri, role, ofObjectToReturn);
  33                 }
  34                 throw new XmlException(Res.GetString(Res.Xml_CannotResolveUrl, absoluteUri.ToString()));
  35             }
  36
  37             if (ofObjectToReturn == null || ofObjectToReturn == typeof(Stream) || ofObjectToReturn == typeof(Object)) {
  38                 return Task.FromResult<Object>(data.AsStream());
  39             }
  40             else if (ofObjectToReturn == typeof(TextReader)) {
  41                 return Task.FromResult<Object>(data.AsTextReader());
  42             }
  43             else {
  44                 throw new XmlException(Res.GetString(Res.Xml_UnsupportedClass));
  45             }
  46         }
  47     }
  48 }