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
  38         {
  39                 XPathNodeIterator source;
  40                 XPathNodeIterator iterator;
  41                 XmlNode previous;
  42                 ArrayList list;
  43                 bool finished;
  44
  45                 #region Constructors
  46
  47                 public XmlIteratorNodeList (XPathNodeIterator iter)
  48                 {
  49                         source = iter;
  50                         iterator = iter.Clone ();
  51                         list = new ArrayList ();
  52                 }
  53
  54                 #endregion
  55
  56                 #region Properties
  57
  58                 public override int Count {
  59                         get {
  60 /*
  61                                 // The performance on Count depends on the
  62                                 // iterator which is actually used. In some
  63                                 // iterators, getting iterator.Count is much
  64                                 // faster.
  65
  66                                 // With (current) implementation in general,
  67                                 // those iterators that requires sorting is
  68                                 // likely to have already-computed arrays, so
  69                                 // for them getting Count does not impact on
  70                                 // performance.
  71
  72                                 // But by default, getting iterator.Count means
  73                                 // it internally iterates all the nodes. That
  74                                 // might result in duplicate iteration (so
  75                                 // ineffective). So here I decided that it
  76                                 // just collects all the nodes to the list.
  77
  78                                 if (!finished) {
  79                                         BaseIterator iter = iterator as BaseIterator;
  80                                         if (iter != null && iter.ReverseAxis || iter is SlashIterator)
  81                                                 return iter.Count;
  82
  83                                         while (iterator.MoveNext ())
  84                                                 list.Add (((IHasXmlNode) iterator.Current).GetNode ());
  85                                         finished = true;
  86                                 }
  87                                 return list.Count;
  88 */
  89                                 // anyways such code that uses
  90                                 // XmlNodeList.Count already gives up
  91                                 // performance. Also, storing things in the
  92                                 // list causes extra memory consumption.
  93                                 return iterator.Count;
  94                         }
  95                 }
  96
  97                 #endregion
  98
  99                 #region Methods
 100
 101                 public override IEnumerator GetEnumerator ()
 102                 {
 103                         if (finished)
 104                                 return list.GetEnumerator ();
 105                         else
 106                                 return new XPathNodeIteratorNodeListIterator (source);
 107 //                              return new XPathNodeIteratorNodeListIterator2 (this);
 108                 }
 109
 110                 public override XmlNode Item (int index)
 111                 {
 112                         if (index < 0)
 113                                 return null;
 114                         if (index < list.Count)
 115                                 return (XmlNode) list [index];
 116                         index++;
 117                         while (iterator.CurrentPosition < index) {
 118                                 if (!iterator.MoveNext ()) {
 119                                         finished = true;
 120                                         return null;
 121                                 }
 122                                 list.Add (((IHasXmlNode) iterator.Current).GetNode ());
 123                         }
 124                         return (XmlNode) list [index - 1];
 125                 }
 126
 127                 #endregion
 128
 129                 class XPathNodeIteratorNodeListIterator : IEnumerator
 130                 {
 131                         XPathNodeIterator iter;
 132                         XPathNodeIterator source;
 133                         public XPathNodeIteratorNodeListIterator (XPathNodeIterator source)
 134                         {
 135                                 this.source = source;
 136                                 Reset ();
 137                         }
 138
 139                         public bool MoveNext ()
 140                         {
 141                                 return iter.MoveNext ();
 142                         }
 143
 144                         public object Current {
 145                                 get { return ((IHasXmlNode) iter.Current).GetNode (); }
 146                         }
 147
 148                         public void Reset ()
 149                         {
 150                                 iter = source.Clone ();
 151                         }
 152                 }
 153
 154                 /*
 155                 class XPathNodeIteratorNodeListIterator2 : IEnumerator
 156                 {
 157                         int current = -1;
 158                         XmlIteratorNodeList source;
 159
 160                         public XPathNodeIteratorNodeListIterator2 (XmlIteratorNodeList source)
 161                         {
 162                                 this.source = source;
 163                         }
 164
 165                         public bool MoveNext ()
 166                         {
 167                                 return source [++current] != null;
 168                         }
 169
 170                         public object Current {
 171                                 get { return source [current]; }
 172                         }
 173
 174                         public void Reset ()
 175                         {
 176                                 current = -1;
 177                         }
 178                 }
 179                 */
 180         }
 181 }