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
  21                 #endregion
  22
  23                 #region Constructor
  24
  25                 public XmlNamespaceManager (XmlNameTable nameTable)
  26                 {
  27                         this.nameTable = nameTable;
  28
  29                         nameTable.Add ("xmlns");
  30                         nameTable.Add ("xml");
  31                         nameTable.Add (String.Empty);
  32                         nameTable.Add ("http://www.w3.org/2000/xmlns/");
  33                         nameTable.Add ("http://www.w3.org/XML/1998/namespace");
  34
  35                         PushScope ();
  36                         currentScope.Namespaces = new Hashtable ();
  37                         currentScope.Namespaces.Add ("xml", "http://www.w3.org/XML/1998/namespace");
  38                         currentScope.Namespaces.Add ("xmlns", "http://www.w3.org/2000/xmlns/");
  39                 }
  40
  41                 #endregion
  42
  43                 #region Properties
  44
  45                 public virtual string DefaultNamespace {
  46                         get { return LookupNamespace (String.Empty); }
  47                 }
  48
  49                 public XmlNameTable NameTable {
  50                         get { return nameTable; }
  51                 }
  52
  53                 #endregion
  54
  55                 #region Methods
  56
  57                 public virtual void AddNamespace (string prefix, string uri)
  58                 {
  59                         if (prefix == null)
  60                                 throw new ArgumentNullException ("prefix", "Value cannot be null.");
  61
  62                         if (uri == null)
  63                                 throw new ArgumentNullException ("uri", "Value cannot be null.");
  64
  65                         if (prefix.Length > 2 && prefix.Substring (0, 3).ToLower () == "xml")
  66                                 throw new ArgumentException ( "Prefixes beginning with \"xml\" (regardless " + "of whether the characters are uppercase, lowercase, or some combination thereof) are reserved for use by XML.", "prefix");
  67
  68                         if (currentScope.Namespaces == null)
  69                                 currentScope.Namespaces = new Hashtable ();
  70
  71                         if (prefix != String.Empty)
  72                                 nameTable.Add (prefix);
  73                         currentScope.Namespaces [prefix] = nameTable.Add (uri);
  74                 }
  75
  76                 public virtual IEnumerator GetEnumerator ()
  77                 {
  78                         if (currentScope.Namespaces == null)
  79                                 currentScope.Namespaces = new Hashtable ();
  80
  81                         return currentScope.Namespaces.Keys.GetEnumerator ();
  82                 }
  83
  84                 public virtual bool HasNamespace (string prefix)
  85                 {
  86                         return currentScope != null && currentScope.Namespaces != null && currentScope.Namespaces.Contains (prefix);
  87                 }
  88
  89                 public virtual string LookupNamespace (string prefix)
  90                 {
  91                         NamespaceScope scope = currentScope;
  92
  93                         while (scope != null) {
  94                                 if (scope.Namespaces != null && scope.Namespaces.Contains (prefix))
  95                                         return scope.Namespaces[prefix] as string;
  96                                 scope = scope.Next;
  97                         }
  98
  99                         switch (prefix) {
 100                         case "xmlns":
 101                                 return nameTable.Get ("http://www.w3.org/2000/xmlns/");
 102                         case "xml":
 103                                 return nameTable.Get ("http://www.w3.org/XML/1998/namespace");
 104                         case "":
 105                                 return nameTable.Get (String.Empty);
 106                         }
 107
 108                         return null;
 109                 }
 110
 111                 public virtual string LookupPrefix (string uri)
 112                 {
 113                         if (uri == null)
 114                                 return null;
 115
 116                         NamespaceScope scope = currentScope;
 117
 118                         while (scope != null)
 119                         {
 120                                 if (scope.Namespaces != null && scope.Namespaces.ContainsValue (uri)) {
 121                                         foreach (DictionaryEntry entry in scope.Namespaces) {
 122                                                 if (entry.Value.ToString() == uri)
 123                                                         return nameTable.Get (entry.Key as string) as string;
 124                                         }
 125                                 }
 126
 127                                 scope = scope.Next;
 128                         }
 129
 130                         // ECMA specifies that this method returns String.Empty
 131                         // in case of no match. But actually MS.NET returns null.
 132                         // For more information,see
 133                         //  http://lists.ximian.com/archives/public/mono-list/2003-January/005071.html
 134                         //return String.Empty;
 135                         return null;
 136                 }
 137
 138                 public virtual bool PopScope ()
 139                 {
 140                         if (currentScope != null)
 141                                 currentScope = currentScope.Next;
 142
 143                         return currentScope != null;
 144                 }
 145
 146                 public virtual void PushScope ()
 147                 {
 148                         NamespaceScope newScope = new NamespaceScope ();
 149                         newScope.Next = currentScope;
 150                         currentScope = newScope;
 151                 }
 152
 153                 public virtual void RemoveNamespace (string prefix, string uri)
 154                 {
 155                         if (prefix == null)
 156                                 throw new ArgumentNullException ("prefix");
 157
 158                         if (uri == null)
 159                                 throw new ArgumentNullException ("uri");
 160
 161                         if (currentScope == null || currentScope.Namespaces == null)
 162                                 return;
 163
 164                         string p = nameTable.Get (prefix);
 165                         string u = nameTable.Get (uri);
 166                         if (p == null || u == null)
 167                                 return;
 168
 169                         string storedUri = currentScope.Namespaces [p] as string;
 170                         if (storedUri == null || storedUri != u)
 171                                 return;
 172
 173                         currentScope.Namespaces.Remove (p);
 174                 }
 175
 176                 #endregion
 177         }
 178
 179         internal class NamespaceScope
 180         {
 181                 internal NamespaceScope Next;
 182                 internal Hashtable Namespaces;
 183         }
 184 }