mcs/class/referencesource/System.Data.SqlXml/System/Xml/Xsl/Runtime/XmlNavigatorStack.cs

   1 //------------------------------------------------------------------------------
   2 // <copyright file="XmlNavigatorStack.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.Xml;
   9 using System.Xml.XPath;
  10 using System.Diagnostics;
  11
  12 namespace System.Xml.Xsl.Runtime {
  13
  14     /// <summary>
  15     /// A dynamic stack of IXmlNavigators.
  16     /// </summary>
  17     internal struct XmlNavigatorStack {
  18         private XPathNavigator[] stkNav;    // Stack of XPathNavigators
  19         private int sp;                     // Stack pointer (size of stack)
  20
  21     #if DEBUG
  22         private const int InitialStackSize = 2;
  23     #else
  24         private const int InitialStackSize = 8;
  25     #endif
  26
  27         /// <summary>
  28         /// Push a navigator onto the stack
  29         /// </summary>
  30         public void Push(XPathNavigator nav) {
  31             if (this.stkNav == null)
  32             {
  33                 this.stkNav = new XPathNavigator[InitialStackSize];
  34             }
  35             else
  36             {
  37                 if (this.sp >= this.stkNav.Length)
  38                 {
  39                     // Resize the stack
  40                     XPathNavigator[] stkOld = this.stkNav;
  41                     this.stkNav = new XPathNavigator[2 * this.sp];
  42                     Array.Copy(stkOld, this.stkNav, this.sp);
  43                 }
  44             }
  45
  46             this.stkNav[this.sp++] = nav;
  47         }
  48
  49         /// <summary>
  50         /// Pop the topmost navigator and return it
  51         /// </summary>
  52         public XPathNavigator Pop() {
  53             Debug.Assert(!IsEmpty);
  54             return this.stkNav[--this.sp];
  55         }
  56
  57         /// <summary>
  58         /// Returns the navigator at the top of the stack without adjusting the stack pointer
  59         /// </summary>
  60         public XPathNavigator Peek() {
  61             Debug.Assert(!IsEmpty);
  62             return this.stkNav[this.sp - 1];
  63         }
  64
  65         /// <summary>
  66         /// Remove all navigators from the stack
  67         /// </summary>
  68         public void Reset() {
  69             this.sp = 0;
  70         }
  71
  72         /// <summary>
  73         /// Returns true if there are no navigators in the stack
  74         /// </summary>
  75         public bool IsEmpty {
  76             get { return this.sp == 0; }
  77         }
  78     }
  79 }