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 ("", "");
  41                         currentScope.Namespaces.Add ("xml", XmlnsXml);
  42                         currentScope.Namespaces.Add ("xmlns", XmlnsXmlns);
  43                 }
  44
  45                 #endregion
  46
  47                 #region Properties
  48
  49                 public virtual string DefaultNamespace {
  50                         get { return LookupNamespace (String.Empty); }
  51                 }
  52
  53                 public XmlNameTable NameTable {
  54                         get { return nameTable; }
  55                 }
  56
  57                 #endregion
  58
  59                 #region Methods
  60
  61                 public virtual void AddNamespace (string prefix, string uri)
  62                 {
  63                         if (prefix == null)
  64                                 throw new ArgumentNullException ("prefix", "Value cannot be null.");
  65
  66                         if (uri == null)
  67                                 throw new ArgumentNullException ("uri", "Value cannot be null.");
  68
  69                         IsValidDeclaration (prefix, uri, true);
  70
  71                         if (currentScope.Namespaces == null)
  72                                 currentScope.Namespaces = new Hashtable ();
  73
  74                         if (prefix != String.Empty)
  75                                 nameTable.Add (prefix);
  76                         currentScope.Namespaces [prefix] = nameTable.Add (uri);
  77                 }
  78
  79                 internal static string IsValidDeclaration (string prefix, string uri, bool throwException)
  80                 {
  81                         string message = null;
  82                         if (prefix == "xml" && uri != XmlnsXml)
  83                                 message = String.Format ("Prefix \"xml\" is only allowed to the fixed uri \"{0}\"", XmlnsXml);
  84                         else if (uri == XmlnsXml)
  85                                 message = String.Format ("Namespace URI \"{0}\" can only be declared with the fixed prefix \"xml\"", XmlnsXml);
  86                         if (message == null && prefix == "xmlns")
  87                                 message = "Declaring prefix named \"xmlns\" is not allowed to any namespace.";
  88                         if (message == null && uri == XmlnsXmlns)
  89                                 message = String.Format ("Namespace URI \"{0}\" cannot be declared with any namespace.", XmlnsXmlns);
  90                         if (message != null && throwException)
  91                                 throw new ArgumentException (message);
  92                         else
  93                                 return message;
  94                 }
  95
  96                 public virtual IEnumerator GetEnumerator ()
  97                 {
  98                         /*
  99                         if (currentScope.Namespaces == null)
 100                                 currentScope.Namespaces = new Hashtable ();
 101
 102                         return currentScope.Namespaces.Keys.GetEnumerator ();
 103                         */
 104
 105                         // In fact it returns such table's enumerator that contains all the namespaces.
 106                         // while HasNamespace() ignores pushed namespaces.
 107                         Hashtable ht = new Hashtable ();
 108                         NamespaceScope scope = currentScope;
 109
 110                         while (scope != null) {
 111                                 if (scope.Namespaces != null) {
 112                                         IEnumerator e = scope.Namespaces.Keys.GetEnumerator ();
 113                                         while (e.MoveNext ()) {
 114                                                 if (!ht.ContainsKey (e.Current))
 115                                                         ht.Add (e.Current, scope.Namespaces [e.Current]);
 116                                         }
 117                                 }
 118                                 scope = scope.Next;
 119                         }
 120                         return ht.Keys.GetEnumerator ();
 121                 }
 122
 123                 public virtual bool HasNamespace (string prefix)
 124                 {
 125                         return currentScope != null && currentScope.Namespaces != null && currentScope.Namespaces.Contains (prefix);
 126                 }
 127
 128                 public virtual string LookupNamespace (string prefix)
 129                 {
 130                         NamespaceScope scope = currentScope;
 131
 132                         while (scope != null) {
 133                                 if (scope.Namespaces != null && scope.Namespaces.Contains (prefix))
 134                                         return scope.Namespaces[prefix] as string;
 135                                 scope = scope.Next;
 136                         }
 137
 138                         switch (prefix) {
 139                         case "xmlns":
 140                                 return nameTable.Get (XmlnsXmlns);
 141                         case "xml":
 142                                 return nameTable.Get (XmlnsXml);
 143                         case "":
 144                                 return nameTable.Get (String.Empty);
 145                         }
 146
 147                         return null;
 148                 }
 149
 150                 public virtual string LookupPrefix (string uri)
 151                 {
 152                         if (uri == null)
 153                                 return null;
 154
 155                         NamespaceScope scope = currentScope;
 156
 157                         while (scope != null)
 158                         {
 159                                 if (scope.Namespaces != null && scope.Namespaces.ContainsValue (uri)) {
 160                                         foreach (DictionaryEntry entry in scope.Namespaces) {
 161                                                 if (entry.Value.ToString() == uri)
 162                                                         return nameTable.Get (entry.Key as string) as string;
 163                                         }
 164                                 }
 165
 166                                 scope = scope.Next;
 167                         }
 168
 169                         // ECMA specifies that this method returns String.Empty
 170                         // in case of no match. But actually MS.NET returns null.
 171                         // For more information,see
 172                         //  http://lists.ximian.com/archives/public/mono-list/2003-January/005071.html
 173                         //return String.Empty;
 174                         return null;
 175                 }
 176
 177                 public virtual bool PopScope ()
 178                 {
 179                         if (currentScope != null)
 180                                 currentScope = currentScope.Next;
 181
 182                         return currentScope != null;
 183                 }
 184
 185                 public virtual void PushScope ()
 186                 {
 187                         NamespaceScope newScope = new NamespaceScope ();
 188                         newScope.Next = currentScope;
 189                         currentScope = newScope;
 190                 }
 191
 192                 public virtual void RemoveNamespace (string prefix, string uri)
 193                 {
 194                         if (prefix == null)
 195                                 throw new ArgumentNullException ("prefix");
 196
 197                         if (uri == null)
 198                                 throw new ArgumentNullException ("uri");
 199
 200                         if (currentScope == null || currentScope.Namespaces == null)
 201                                 return;
 202
 203                         string p = nameTable.Get (prefix);
 204                         string u = nameTable.Get (uri);
 205                         if (p == null || u == null)
 206                                 return;
 207
 208                         string storedUri = currentScope.Namespaces [p] as string;
 209                         if (storedUri == null || storedUri != u)
 210                                 return;
 211
 212                         currentScope.Namespaces.Remove (p);
 213                 }
 214
 215                 #endregion
 216         }
 217
 218         internal class NamespaceScope
 219         {
 220                 internal NamespaceScope Next;
 221                 internal Hashtable Namespaces;
 222         }
 223 }