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

   1 //
   2 // System.Xml.XmlNodeList
   3 //
   4 // Author:
   5 //   Kral Ferch <kral_ferch@hotmail.com>
   6 //
   7 // (C) 2002 Kral Ferch
   8 //
   9
  10 using System;
  11 using System.Collections;
  12
  13 namespace System.Xml
  14 {
  15         public class XmlNodeListChildren : XmlNodeList
  16         {
  17                 #region Enumerator
  18
  19                 private class Enumerator : IEnumerator
  20                 {
  21                         XmlNode parent;
  22                         XmlLinkedNode currentChild;
  23                         bool passedLastNode;
  24
  25                         internal Enumerator (XmlNode parent)
  26                         {
  27                                 currentChild = null;
  28                                 this.parent = parent;
  29                                 passedLastNode = false;
  30                         }
  31
  32                         public virtual object Current {
  33                                 get {
  34                                         if ((currentChild == null) ||
  35                                                 (parent.LastLinkedChild == null) ||
  36                                                 (passedLastNode == true))
  37                                                 throw new InvalidOperationException();
  38
  39                                         return currentChild;
  40                                 }
  41                         }
  42
  43                         public virtual bool MoveNext()
  44                         {
  45                                 bool movedNext = true;
  46
  47                                 if (parent.LastLinkedChild == null) {
  48                                         movedNext = false;
  49                                 }
  50                                 else if (currentChild == null) {
  51                                         currentChild = parent.LastLinkedChild.NextLinkedSibling;
  52                                 }
  53                                 else {
  54                                         if (Object.ReferenceEquals(currentChild, parent.LastLinkedChild)) {
  55                                                 movedNext = false;
  56                                                 passedLastNode = true;
  57                                         }
  58                                         else {
  59                                                 currentChild = currentChild.NextLinkedSibling;
  60                                         }
  61                                 }
  62
  63                                 return movedNext;
  64                         }
  65
  66                         public virtual void Reset()
  67                         {
  68                                 currentChild = null;
  69                         }
  70                 }
  71
  72                 #endregion
  73
  74                 #region Fields
  75
  76                 XmlNode parent;
  77
  78                 #endregion
  79
  80                 #region Constructors
  81                 public XmlNodeListChildren(XmlNode parent)
  82                 {
  83                         this.parent = parent;
  84                 }
  85
  86                 #endregion
  87
  88                 #region Properties
  89
  90                 public override int Count {
  91                         get {
  92                                 int count = 0;
  93
  94                                 if (parent.LastLinkedChild != null) {
  95                                         XmlLinkedNode currentChild = parent.LastLinkedChild.NextLinkedSibling;
  96
  97                                         count = 1;
  98                                         while (!Object.ReferenceEquals(currentChild, parent.LastLinkedChild)) {
  99                                                 currentChild = currentChild.NextLinkedSibling;
 100                                                 count++;
 101                                         }
 102                                 }
 103
 104                                 return count;
 105                         }
 106                 }
 107
 108                 #endregion
 109
 110                 #region Methods
 111
 112                 public override IEnumerator GetEnumerator ()
 113                 {
 114                         return new Enumerator(parent);
 115                 }
 116
 117                 public override XmlNode Item (int index)
 118                 {
 119                         XmlNode requestedNode = null;
 120
 121                         // Instead of checking for && index < Count which has to walk
 122                         // the whole list to get a count, we'll just keep a count since
 123                         // we have to walk the list anyways to get to index.
 124                         if ((index >= 0) && (parent.LastLinkedChild != null)) {
 125                                 XmlLinkedNode currentChild = parent.LastLinkedChild.NextLinkedSibling;
 126                                 int count = 0;
 127
 128                                 while ((count < index) && !Object.ReferenceEquals(currentChild, parent.LastLinkedChild))
 129                                 {
 130                                         currentChild = currentChild.NextLinkedSibling;
 131                                         count++;
 132                                 }
 133
 134                                 if (count == index) {
 135                                         requestedNode = currentChild;
 136                                 }
 137                         }
 138
 139                         return requestedNode;
 140                 }
 141
 142                 #endregion
 143         }
 144
 145
 146 }