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 //
  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
  34 namespace System.Xml
  35 {
  36         internal class XmlNodeListChildren : XmlNodeList
  37         {
  38                 #region Enumerator
  39
  40                 private class Enumerator : IEnumerator
  41                 {
  42                         XmlNode parent;
  43                         XmlLinkedNode currentChild;
  44                         bool passedLastNode;
  45
  46                         internal Enumerator (XmlNode parent)
  47                         {
  48                                 currentChild = null;
  49                                 this.parent = parent;
  50                                 passedLastNode = false;
  51                         }
  52
  53                         public virtual object Current {
  54                                 get {
  55                                         if ((currentChild == null) ||
  56                                                 (parent.LastLinkedChild == null) ||
  57                                                 (passedLastNode == true))
  58                                                 throw new InvalidOperationException();
  59
  60                                         return currentChild;
  61                                 }
  62                         }
  63
  64                         public virtual bool MoveNext()
  65                         {
  66                                 bool movedNext = true;
  67
  68                                 if (parent.LastLinkedChild == null) {
  69                                         movedNext = false;
  70                                 }
  71                                 else if (currentChild == null) {
  72                                         currentChild = parent.LastLinkedChild.NextLinkedSibling;
  73                                 }
  74                                 else {
  75                                         if (Object.ReferenceEquals(currentChild, parent.LastLinkedChild)) {
  76                                                 movedNext = false;
  77                                                 passedLastNode = true;
  78                                         }
  79                                         else {
  80                                                 currentChild = currentChild.NextLinkedSibling;
  81                                         }
  82                                 }
  83
  84                                 return movedNext;
  85                         }
  86
  87                         public virtual void Reset()
  88                         {
  89                                 currentChild = null;
  90                         }
  91                 }
  92
  93                 #endregion
  94
  95                 #region Fields
  96
  97                 XmlNode parent;
  98
  99                 #endregion
 100
 101                 #region Constructors
 102                 public XmlNodeListChildren(XmlNode parent)
 103                 {
 104                         this.parent = parent;
 105                 }
 106
 107                 #endregion
 108
 109                 #region Properties
 110
 111                 public override int Count {
 112                         get {
 113                                 int count = 0;
 114
 115                                 if (parent.LastLinkedChild != null) {
 116                                         XmlLinkedNode currentChild = parent.LastLinkedChild.NextLinkedSibling;
 117
 118                                         count = 1;
 119                                         while (!Object.ReferenceEquals(currentChild, parent.LastLinkedChild)) {
 120                                                 currentChild = currentChild.NextLinkedSibling;
 121                                                 count++;
 122                                         }
 123                                 }
 124
 125                                 return count;
 126                         }
 127                 }
 128
 129                 #endregion
 130
 131                 #region Methods
 132
 133                 public override IEnumerator GetEnumerator ()
 134                 {
 135                         return new Enumerator(parent);
 136                 }
 137
 138                 public override XmlNode Item (int index)
 139                 {
 140                         XmlNode requestedNode = null;
 141
 142                         // Return null if index is out of range. by  DOM design.
 143                         if (Count <= index)
 144                                 return null;
 145
 146                         // Instead of checking for && index < Count which has to walk
 147                         // the whole list to get a count, we'll just keep a count since
 148                         // we have to walk the list anyways to get to index.
 149                         if ((index >= 0) && (parent.LastLinkedChild != null)) {
 150                                 XmlLinkedNode currentChild = parent.LastLinkedChild.NextLinkedSibling;
 151                                 int count = 0;
 152
 153                                 while ((count < index) && !Object.ReferenceEquals(currentChild, parent.LastLinkedChild))
 154                                 {
 155                                         currentChild = currentChild.NextLinkedSibling;
 156                                         count++;
 157                                 }
 158
 159                                 if (count == index) {
 160                                         requestedNode = currentChild;
 161                                 }
 162                         }
 163
 164                         return requestedNode;
 165                 }
 166
 167                 #endregion
 168         }
 169
 170
 171 }