mcs/class/referencesource/System/sys/system/configuration/DictionarySectionHandler.cs

   1 //------------------------------------------------------------------------------
   2 // <copyright file="DictionarySectionHandler.cs" company="Microsoft">
   3 //     Copyright (c) Microsoft Corporation.  All rights reserved.
   4 // </copyright>
   5 //------------------------------------------------------------------------------
   6
   7 namespace System.Configuration {
   8     using System.Collections;
   9     using System.Collections.Specialized;
  10     using System.Xml;
  11     using System.Globalization;
  12
  13     /// <devdoc>
  14     /// Simple dictionary config factory
  15     /// config is a dictionary mapping key-&gt;value
  16     ///
  17     ///     &lt;add key="name" value="text"&gt;  sets key=text
  18     ///     &lt;remove key="name"&gt;            removes the definition of key
  19     ///     &lt;clear&gt;                        removes all definitions
  20     ///
  21     /// </devdoc>
  22     public class DictionarySectionHandler : IConfigurationSectionHandler {
  23
  24         /// <devdoc>
  25         /// Given a partially composed config object (possibly null)
  26         /// and some input from the config system, return a
  27         /// further partially composed config object
  28         /// </devdoc>
  29         public virtual object Create(Object parent, Object context, XmlNode section) {
  30             Hashtable res;
  31
  32             // start res off as a shallow clone of the parent
  33
  34             if (parent == null)
  35                 res = new Hashtable(StringComparer.OrdinalIgnoreCase);
  36             else
  37                 res = (Hashtable)((Hashtable)parent).Clone();
  38
  39             // process XML
  40
  41             HandlerBase.CheckForUnrecognizedAttributes(section);
  42
  43             foreach (XmlNode child in section.ChildNodes) {
  44
  45                 // skip whitespace and comments, throws if non-element
  46                 if (HandlerBase.IsIgnorableAlsoCheckForNonElement(child))
  47                     continue;
  48
  49                 // handle <add>, <remove>, <clear> tags
  50                 if (child.Name == "add") {
  51                     HandlerBase.CheckForChildNodes(child);
  52                     String key = HandlerBase.RemoveRequiredAttribute(child, KeyAttributeName);
  53                     String value;
  54                     if (ValueRequired)
  55                         value = HandlerBase.RemoveRequiredAttribute(child, ValueAttributeName);
  56                     else
  57                         value = HandlerBase.RemoveAttribute(child, ValueAttributeName);
  58                     HandlerBase.CheckForUnrecognizedAttributes(child);
  59
  60                     if (value == null)
  61                         value = "";
  62
  63                     res[key] = value;
  64                 }
  65                 else if (child.Name == "remove") {
  66                     HandlerBase.CheckForChildNodes(child);
  67                     String key = HandlerBase.RemoveRequiredAttribute(child, KeyAttributeName);
  68                     HandlerBase.CheckForUnrecognizedAttributes(child);
  69
  70                     res.Remove(key);
  71                 }
  72                 else if (child.Name.Equals("clear")) {
  73                     HandlerBase.CheckForChildNodes(child);
  74                     HandlerBase.CheckForUnrecognizedAttributes(child);
  75                     res.Clear();
  76                 }
  77                 else {
  78                     HandlerBase.ThrowUnrecognizedElement(child);
  79                 }
  80             }
  81
  82             return res;
  83         }
  84
  85         /// <devdoc>
  86         ///    Make the name of the key attribute configurable by derived classes.
  87         /// </devdoc>
  88         protected virtual string KeyAttributeName {
  89             get { return "key";}
  90         }
  91
  92         /// <devdoc>
  93         ///    Make the name of the value attribute configurable by derived classes.
  94         /// </devdoc>
  95         protected virtual string ValueAttributeName {
  96             get { return "value";}
  97         }
  98
  99         //
 100         internal virtual bool ValueRequired {
 101             get { return false; }
 102         }
 103     }
 104 }