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
  38         {
  39                 XPathNodeIterator source;
  40                 XPathNodeIterator iterator;
  41                 ArrayList list;
  42                 bool finished;
  43
  44                 #region Constructors
  45
  46                 public XmlIteratorNodeList (XPathNodeIterator iter)
  47                 {
  48                         source = iter;
  49                         iterator = iter.Clone ();
  50                         list = new ArrayList ();
  51                 }
  52
  53                 #endregion
  54
  55                 #region Properties
  56
  57                 public override int Count {
  58                         get {
  59 /*
  60                                 // The performance on Count depends on the
  61                                 // iterator which is actually used. In some
  62                                 // iterators, getting iterator.Count is much
  63                                 // faster.
  64
  65                                 // With (current) implementation in general,
  66                                 // those iterators that requires sorting is
  67                                 // likely to have already-computed arrays, so
  68                                 // for them getting Count does not impact on
  69                                 // performance.
  70
  71                                 // But by default, getting iterator.Count means
  72                                 // it internally iterates all the nodes. That
  73                                 // might result in duplicate iteration (so
  74                                 // ineffective). So here I decided that it
  75                                 // just collects all the nodes to the list.
  76
  77                                 if (!finished) {
  78                                         BaseIterator iter = iterator as BaseIterator;
  79                                         if (iter != null && iter.ReverseAxis || iter is SlashIterator)
  80                                                 return iter.Count;
  81
  82                                         while (iterator.MoveNext ())
  83                                                 list.Add (((IHasXmlNode) iterator.Current).GetNode ());
  84                                         finished = true;
  85                                 }
  86                                 return list.Count;
  87 */
  88                                 // anyways such code that uses
  89                                 // XmlNodeList.Count already gives up
  90                                 // performance. Also, storing things in the
  91                                 // list causes extra memory consumption.
  92                                 return iterator.Count;
  93                         }
  94                 }
  95
  96                 #endregion
  97
  98                 #region Methods
  99
 100                 public override IEnumerator GetEnumerator ()
 101                 {
 102                         if (finished)
 103                                 return list.GetEnumerator ();
 104                         else
 105                                 return new XPathNodeIteratorNodeListIterator (source);
 106 //                              return new XPathNodeIteratorNodeListIterator2 (this);
 107                 }
 108
 109                 public override XmlNode Item (int index)
 110                 {
 111                         if (index < 0)
 112                                 return null;
 113                         if (index < list.Count)
 114                                 return (XmlNode) list [index];
 115                         index++;
 116                         while (iterator.CurrentPosition < index) {
 117                                 if (!iterator.MoveNext ()) {
 118                                         finished = true;
 119                                         return null;
 120                                 }
 121                                 list.Add (((IHasXmlNode) iterator.Current).GetNode ());
 122                         }
 123                         return (XmlNode) list [index - 1];
 124                 }
 125
 126                 #endregion
 127
 128                 class XPathNodeIteratorNodeListIterator : IEnumerator
 129                 {
 130                         XPathNodeIterator iter;
 131                         XPathNodeIterator source;
 132                         public XPathNodeIteratorNodeListIterator (XPathNodeIterator source)
 133                         {
 134                                 this.source = source;
 135                                 Reset ();
 136                         }
 137
 138                         public bool MoveNext ()
 139                         {
 140                                 return iter.MoveNext ();
 141                         }
 142
 143                         public object Current {
 144                                 get { return ((IHasXmlNode) iter.Current).GetNode (); }
 145                         }
 146
 147                         public void Reset ()
 148                         {
 149                                 iter = source.Clone ();
 150                         }
 151                 }
 152
 153                 /*
 154                 class XPathNodeIteratorNodeListIterator2 : IEnumerator
 155                 {
 156                         int current = -1;
 157                         XmlIteratorNodeList source;
 158
 159                         public XPathNodeIteratorNodeListIterator2 (XmlIteratorNodeList source)
 160                         {
 161                                 this.source = source;
 162                         }
 163
 164                         public bool MoveNext ()
 165                         {
 166                                 return source [++current] != null;
 167                         }
 168
 169                         public object Current {
 170                                 get { return source [current]; }
 171                         }
 172
 173                         public void Reset ()
 174                         {
 175                                 current = -1;
 176                         }
 177                 }
 178                 */
 179         }
 180 }