mcs/class/referencesource/System.Data.SqlXml/System/Xml/Xsl/QIL/SubstitutionList.cs

   1 //------------------------------------------------------------------------------
   2 // <copyright file="SubstitutionList.cs" company="Microsoft">
   3 //     Copyright (c) Microsoft Corporation.  All rights reserved.
   4 // </copyright>
   5 // <owner current="true" primary="true">Microsoft</owner>
   6 //------------------------------------------------------------------------------
   7 using System;
   8 using System.Collections;
   9 using System.Diagnostics;
  10
  11 namespace System.Xml.Xsl.Qil {
  12
  13     /// <summary>
  14     /// Data structure for use in CloneAndReplace
  15     /// </summary>
  16     /// <remarks>Isolates the many QilNode classes from changes in
  17     /// the underlying data structure.</remarks>
  18     internal sealed class SubstitutionList {
  19         //
  20         private ArrayList s;
  21
  22         public SubstitutionList() {
  23             this.s = new ArrayList(4);
  24         }
  25
  26         /// <summary>
  27         /// Add a substituion pair
  28         /// </summary>
  29         /// <param name="find">a node to be replaced</param>
  30         /// <param name="replace">its replacement</param>
  31         public void AddSubstitutionPair(QilNode find, QilNode replace) {
  32             s.Add(find);
  33             s.Add(replace);
  34         }
  35
  36         /// <summary>
  37         /// Remove the last a substituion pair
  38         /// </summary>
  39         public void RemoveLastSubstitutionPair() {
  40             s.RemoveRange(s.Count - 2, 2);
  41         }
  42
  43         /// <summary>
  44         /// Remove the last N substitution pairs
  45         /// </summary>
  46         public void RemoveLastNSubstitutionPairs(int n) {
  47             Debug.Assert(n >= 0, "n must be nonnegative");
  48             if (n > 0) {
  49                 n *= 2;
  50                 s.RemoveRange(s.Count - n, n);
  51             }
  52         }
  53
  54         /// <summary>
  55         /// Find the replacement for a node
  56         /// </summary>
  57         /// <param name="n">the node to replace</param>
  58         /// <returns>null if no replacement is found</returns>
  59         public QilNode FindReplacement(QilNode n) {
  60             Debug.Assert(s.Count % 2 == 0);
  61             for (int i = s.Count-2; i >= 0; i-=2)
  62                 if (s[i] == n)
  63                     return (QilNode)s[i+1];
  64             return null;
  65         }
  66     }
  67 }