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

   1 //
   2 // System.Xml.XmlIteratorNodeList
   3 //
   4 // Author:
   5 //      Atsushi Enomoto <atsushi@ximian.com>
   6 //
   7 // (C) 2006 Novell Inc.
   8 //
   9
  10 //
  11 // Permission is hereby granted, free of charge, to any person obtaining
  12 // a copy of this software and associated documentation files (the
  13 // "Software"), to deal in the Software without restriction, including
  14 // without limitation the rights to use, copy, modify, merge, publish,
  15 // distribute, sublicense, and/or sell copies of the Software, and to
  16 // permit persons to whom the Software is furnished to do so, subject to
  17 // the following conditions:
  18 //
  19 // The above copyright notice and this permission notice shall be
  20 // included in all copies or substantial portions of the Software.
  21 //
  22 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  23 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  24 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  25 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  26 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  27 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  28 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  29 //
  30
  31 using System;
  32 using System.Collections;
  33 using System.Xml.XPath;
  34
  35 namespace System.Xml
  36 {
  37         internal class XmlIteratorNodeList : XmlNodeList//, IDisposable
  38         {
  39                 //XmlDocument doc;
  40                 XPathNodeIterator source;
  41                 XPathNodeIterator iterator;
  42                 ArrayList list;
  43                 bool finished;
  44
  45                 #region Constructors
  46
  47                 public XmlIteratorNodeList (XmlDocument doc, XPathNodeIterator iter)
  48                 {
  49                         if (doc == null)
  50                                 throw new Exception ("huh?");
  51                         //this.doc = doc;
  52                         //doc.NodeRemoving += SaveNodeList;
  53                         source = iter;
  54                         iterator = iter.Clone ();
  55                         list = new ArrayList ();
  56                 }
  57
  58                 #endregion
  59
  60                 #region Properties
  61
  62                 public override int Count {
  63                         get {
  64 /*
  65                                 // The performance on Count depends on the
  66                                 // iterator which is actually used. In some
  67                                 // iterators, getting iterator.Count is much
  68                                 // faster.
  69
  70                                 // With (current) implementation in general,
  71                                 // those iterators that requires sorting is
  72                                 // likely to have already-computed arrays, so
  73                                 // for them getting Count does not impact on
  74                                 // performance.
  75
  76                                 // But by default, getting iterator.Count means
  77                                 // it internally iterates all the nodes. That
  78                                 // might result in duplicate iteration (so
  79                                 // ineffective). So here I decided that it
  80                                 // just collects all the nodes to the list.
  81
  82                                 if (!finished) {
  83                                         BaseIterator iter = iterator as BaseIterator;
  84                                         if (iter != null && iter.ReverseAxis || iter is SlashIterator)
  85                                                 return iter.Count;
  86
  87                                         while (iterator.MoveNext ())
  88                                                 list.Add (((IHasXmlNode) iterator.Current).GetNode ());
  89                                         finished = true;
  90                                 }
  91                                 return list.Count;
  92 */
  93                                 // anyways such code that uses
  94                                 // XmlNodeList.Count already gives up
  95                                 // performance. Also, storing things in the
  96                                 // list causes extra memory consumption.
  97                                 return iterator.Count;
  98                         }
  99                 }
 100
 101                 #endregion
 102
 103                 #region Methods
 104
 105                 /*
 106                 void IDisposable.Dispose ()
 107                 {
 108                         if (!event_detached) {
 109                                 event_detached = true;
 110                                 doc.NodeRemoving -= SaveNodeList;
 111                         }
 112                 }
 113
 114                 void SaveNodeList (object o, XmlNodeChangedEventArgs e)
 115                 {
 116                         if (Item (Count) != null || !finished)
 117                                 throw new Exception (); // dummy. It accesses to the end of the list
 118                         doc.NodeRemoving -= SaveNodeList;
 119                         event_detached = true;
 120                 }
 121                 */
 122
 123                 public override IEnumerator GetEnumerator ()
 124                 {
 125                         if (finished)
 126                                 return list.GetEnumerator ();
 127                         else
 128                                 return new XPathNodeIteratorNodeListIterator (source);
 129                                 //return new XPathNodeIteratorNodeListIterator2 (this);
 130                 }
 131
 132                 public override XmlNode Item (int index)
 133                 {
 134                         if (index < 0)
 135                                 return null;
 136                         if (index < list.Count)
 137                                 return (XmlNode) list [index];
 138                         index++;
 139                         while (iterator.CurrentPosition < index) {
 140                                 if (!iterator.MoveNext ()) {
 141                                         finished = true;
 142                                         return null;
 143                                 }
 144                                 list.Add (((IHasXmlNode) iterator.Current).GetNode ());
 145                         }
 146                         return (XmlNode) list [index - 1];
 147                 }
 148
 149                 #endregion
 150
 151                 // FIXME: switch to XPathNodeIteratorNodeListIterator2.
 152                 class XPathNodeIteratorNodeListIterator : IEnumerator
 153                 {
 154                         XPathNodeIterator iter;
 155                         XPathNodeIterator source;
 156                         public XPathNodeIteratorNodeListIterator (XPathNodeIterator source)
 157                         {
 158                                 this.source = source;
 159                                 Reset ();
 160                         }
 161
 162                         public bool MoveNext ()
 163                         {
 164                                 return iter.MoveNext ();
 165                         }
 166
 167                         public object Current {
 168                                 get { return ((IHasXmlNode) iter.Current).GetNode (); }
 169                         }
 170
 171                         public void Reset ()
 172                         {
 173                                 iter = source.Clone ();
 174                         }
 175                 }
 176
 177                 /*
 178                 class XPathNodeIteratorNodeListIterator2 : IEnumerator
 179                 {
 180                         int current = -1;
 181                         XmlIteratorNodeList source;
 182
 183                         public XPathNodeIteratorNodeListIterator2 (XmlIteratorNodeList source)
 184                         {
 185                                 this.source = source;
 186                         }
 187
 188                         public bool MoveNext ()
 189                         {
 190                                 return source [++current] != null;
 191                         }
 192
 193                         public object Current {
 194                                 get { return source [current]; }
 195                         }
 196
 197                         public void Reset ()
 198                         {
 199                                 current = -1;
 200                         }
 201                 }
 202                 */
 203         }
 204 }