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                                 currentScope.Namespaces [prefix] = nameTable.Add (uri);
  70                         else
  71                                 currentScope.Namespaces.Add (nameTable.Add (prefix), nameTable.Add (uri));
  72                 }
  73
  74                 public virtual IEnumerator GetEnumerator ()
  75                 {
  76                         if (currentScope.Namespaces == null)
  77                                 currentScope.Namespaces = new Hashtable ();
  78
  79                         return currentScope.Namespaces.Keys.GetEnumerator ();
  80                 }
  81
  82                 public virtual bool HasNamespace (string prefix)
  83                 {
  84                         return currentScope != null && currentScope.Namespaces != null && currentScope.Namespaces.Contains (prefix);
  85                 }
  86
  87                 public virtual string LookupNamespace (string prefix)
  88                 {
  89                         NamespaceScope scope = currentScope;
  90
  91                         while (scope != null) {
  92                                 if (scope.Namespaces != null && scope.Namespaces.Contains (prefix))
  93                                         return scope.Namespaces[prefix] as string;
  94                                 scope = scope.Next;
  95                         }
  96
  97                         switch (prefix) {
  98                         case "xmlns":
  99                                 return nameTable.Get ("http://www.w3.org/2000/xmlns/");
 100                         case "xml":
 101                                 return nameTable.Get ("http://www.w3.org/XML/1998/namespace");
 102                         case "":
 103                                 return nameTable.Get (String.Empty);
 104                         }
 105
 106                         return null;
 107                 }
 108
 109                 public virtual string LookupPrefix (string uri)
 110                 {
 111                         if (uri == null)
 112                                 return null;
 113
 114                         NamespaceScope scope = currentScope;
 115
 116                         while (scope != null)
 117                         {
 118                                 if (scope.Namespaces != null && scope.Namespaces.ContainsValue (uri)) {
 119                                         foreach (DictionaryEntry entry in scope.Namespaces) {
 120                                                 if (entry.Value.ToString() == uri)
 121                                                         return nameTable.Get (entry.Key as string) as string;
 122                                         }
 123                                 }
 124
 125                                 scope = scope.Next;
 126                         }
 127
 128                         return String.Empty;
 129                 }
 130
 131                 public virtual bool PopScope ()
 132                 {
 133                         if (currentScope != null)
 134                                 currentScope = currentScope.Next;
 135
 136                         return currentScope != null;
 137                 }
 138
 139                 public virtual void PushScope ()
 140                 {
 141                         NamespaceScope newScope = new NamespaceScope ();
 142                         newScope.Next = currentScope;
 143                         currentScope = newScope;
 144                 }
 145
 146                 public virtual void RemoveNamespace (string prefix, string uri)
 147                 {
 148                         if (prefix == null)
 149                                 throw new ArgumentNullException ("prefix");
 150
 151                         if (uri == null)
 152                                 throw new ArgumentNullException ("uri");
 153
 154                         if (currentScope == null || currentScope.Namespaces == null)
 155                                 return;
 156
 157                         string p = nameTable.Get (prefix);
 158                         string u = nameTable.Get (uri);
 159                         if (p == null || u == null)
 160                                 return;
 161
 162                         string storedUri = currentScope.Namespaces [p] as string;
 163                         if (storedUri == null || storedUri != u)
 164                                 return;
 165
 166                         currentScope.Namespaces.Remove (p);
 167                 }
 168
 169                 #endregion
 170         }
 171
 172         internal class NamespaceScope
 173         {
 174                 internal NamespaceScope Next;
 175                 internal Hashtable Namespaces;
 176         }
 177 }