mcs/class/System.XML/System.Xml/XmlNamespaceManager.cs

   1 //
   2 // XmlNamespaceManager.cs
   3 //
   4 // Author:
   5 //   Jason Diamond (jason@injektilo.org)
   6 //
   7 // (C) 2001 Jason Diamond  http://injektilo.org/
   8 //
   9
  10 using System.Collections;
  11
  12 namespace System.Xml
  13 {
  14         public class XmlNamespaceManager : IEnumerable
  15         {
  16                 #region Fields
  17
  18                 private XmlNameTable nameTable;
  19                 private NamespaceScope currentScope;
  20                 internal const string XmlnsXml = "http://www.w3.org/XML/1998/namespace";
  21                 internal const string XmlnsXmlns = "http://www.w3.org/2000/xmlns/";
  22
  23                 #endregion
  24
  25                 #region Constructor
  26
  27                 internal XmlNamespaceManager () {}
  28                 public XmlNamespaceManager (XmlNameTable nameTable)
  29                 {
  30                         this.nameTable = nameTable;
  31
  32                         nameTable.Add ("xmlns");
  33                         nameTable.Add ("xml");
  34                         nameTable.Add (String.Empty);
  35                         nameTable.Add (XmlnsXmlns);
  36                         nameTable.Add (XmlnsXml);
  37
  38                         PushScope ();
  39                         currentScope.Namespaces = new Hashtable ();
  40                         currentScope.Namespaces.Add ("xml", XmlnsXml);
  41                         currentScope.Namespaces.Add ("xmlns", XmlnsXmlns);
  42                 }
  43
  44                 #endregion
  45
  46                 #region Properties
  47
  48                 public virtual string DefaultNamespace {
  49                         get { return LookupNamespace (String.Empty); }
  50                 }
  51
  52                 public XmlNameTable NameTable {
  53                         get { return nameTable; }
  54                 }
  55
  56                 #endregion
  57
  58                 #region Methods
  59
  60                 public virtual void AddNamespace (string prefix, string uri)
  61                 {
  62                         if (prefix == null)
  63                                 throw new ArgumentNullException ("prefix", "Value cannot be null.");
  64
  65                         if (uri == null)
  66                                 throw new ArgumentNullException ("uri", "Value cannot be null.");
  67
  68                         IsValidDeclaration (prefix, uri, true);
  69
  70                         if (currentScope.Namespaces == null)
  71                                 currentScope.Namespaces = new Hashtable ();
  72
  73                         if (prefix != String.Empty)
  74                                 nameTable.Add (prefix);
  75                         currentScope.Namespaces [prefix] = nameTable.Add (uri);
  76                 }
  77
  78                 internal static string IsValidDeclaration (string prefix, string uri, bool throwException)
  79                 {
  80                         string message = null;
  81                         if (prefix == "xml" && uri != XmlnsXml)
  82                                 message = String.Format ("Prefix \"xml\" is only allowed to the fixed uri \"{0}\"", XmlnsXml);
  83                         else if (uri == XmlnsXml)
  84                                 message = String.Format ("Namespace URI \"{0}\" can only be declared with the fixed prefix \"xml\"", XmlnsXml);
  85                         if (message == null && prefix == "xmlns")
  86                                 message = "Declaring prefix named \"xmlns\" is not allowed to any namespace.";
  87                         if (message == null && uri == XmlnsXmlns)
  88                                 message = String.Format ("Namespace URI \"{0}\" cannot be declared with any namespace.", XmlnsXmlns);
  89                         if (message != null && throwException)
  90                                 throw new ArgumentException (message);
  91                         else
  92                                 return message;
  93                 }
  94
  95                 public virtual IEnumerator GetEnumerator ()
  96                 {
  97                         if (currentScope.Namespaces == null)
  98                                 currentScope.Namespaces = new Hashtable ();
  99
 100                         return currentScope.Namespaces.Keys.GetEnumerator ();
 101                 }
 102
 103                 public virtual bool HasNamespace (string prefix)
 104                 {
 105                         return currentScope != null && currentScope.Namespaces != null && currentScope.Namespaces.Contains (prefix);
 106                 }
 107
 108                 public virtual string LookupNamespace (string prefix)
 109                 {
 110                         NamespaceScope scope = currentScope;
 111
 112                         while (scope != null) {
 113                                 if (scope.Namespaces != null && scope.Namespaces.Contains (prefix))
 114                                         return scope.Namespaces[prefix] as string;
 115                                 scope = scope.Next;
 116                         }
 117
 118                         switch (prefix) {
 119                         case "xmlns":
 120                                 return nameTable.Get (XmlnsXmlns);
 121                         case "xml":
 122                                 return nameTable.Get (XmlnsXml);
 123                         case "":
 124                                 return nameTable.Get (String.Empty);
 125                         }
 126
 127                         return null;
 128                 }
 129
 130                 public virtual string LookupPrefix (string uri)
 131                 {
 132                         if (uri == null)
 133                                 return null;
 134
 135                         NamespaceScope scope = currentScope;
 136
 137                         while (scope != null)
 138                         {
 139                                 if (scope.Namespaces != null && scope.Namespaces.ContainsValue (uri)) {
 140                                         foreach (DictionaryEntry entry in scope.Namespaces) {
 141                                                 if (entry.Value.ToString() == uri)
 142                                                         return nameTable.Get (entry.Key as string) as string;
 143                                         }
 144                                 }
 145
 146                                 scope = scope.Next;
 147                         }
 148
 149                         // ECMA specifies that this method returns String.Empty
 150                         // in case of no match. But actually MS.NET returns null.
 151                         // For more information,see
 152                         //  http://lists.ximian.com/archives/public/mono-list/2003-January/005071.html
 153                         //return String.Empty;
 154                         return null;
 155                 }
 156
 157                 public virtual bool PopScope ()
 158                 {
 159                         if (currentScope != null)
 160                                 currentScope = currentScope.Next;
 161
 162                         return currentScope != null;
 163                 }
 164
 165                 public virtual void PushScope ()
 166                 {
 167                         NamespaceScope newScope = new NamespaceScope ();
 168                         newScope.Next = currentScope;
 169                         currentScope = newScope;
 170                 }
 171
 172                 public virtual void RemoveNamespace (string prefix, string uri)
 173                 {
 174                         if (prefix == null)
 175                                 throw new ArgumentNullException ("prefix");
 176
 177                         if (uri == null)
 178                                 throw new ArgumentNullException ("uri");
 179
 180                         if (currentScope == null || currentScope.Namespaces == null)
 181                                 return;
 182
 183                         string p = nameTable.Get (prefix);
 184                         string u = nameTable.Get (uri);
 185                         if (p == null || u == null)
 186                                 return;
 187
 188                         string storedUri = currentScope.Namespaces [p] as string;
 189                         if (storedUri == null || storedUri != u)
 190                                 return;
 191
 192                         currentScope.Namespaces.Remove (p);
 193                 }
 194
 195                 #endregion
 196         }
 197
 198         internal class NamespaceScope
 199         {
 200                 internal NamespaceScope Next;
 201                 internal Hashtable Namespaces;
 202         }
 203 }