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