Experiments/Attic/Rook/Castle.Rook.Compiler/Parser/antlr/TokenQueue.cs

   1 using System;
   2
   3 namespace antlr
   4 {
   5         /*ANTLR Translator Generator
   6         * Project led by Terence Parr at http://www.jGuru.com
   7         * Software rights: http://www.antlr.org/license.html
   8         *
   9         * $Id:$
  10         */
  11
  12         //
  13         // ANTLR C# Code Generator by Micheal Jordan
  14         //                            Kunle Odutola       : kunle UNDERSCORE odutola AT hotmail DOT com
  15         //                            Anthony Oguntimehin
  16         //
  17         // With many thanks to Eric V. Smith from the ANTLR list.
  18         //
  19
  20         /*A private circular buffer object used by the token buffer */
  21
  22         class TokenQueue
  23         {
  24                 /*Physical circular buffer of tokens */
  25                 private IToken[] buffer;
  26                 /*buffer.length-1 for quick modulos */
  27                 private int sizeLessOne;
  28                 /*physical index of front token */
  29                 private int offset;
  30                 /*number of tokens in the queue */
  31                 protected internal int nbrEntries;
  32
  33                 public TokenQueue(int minSize)
  34                 {
  35                         // Find first power of 2 >= to requested size
  36                         int size;
  37                         if (minSize < 0)
  38                         {
  39                                 init(16); // pick some value for them
  40                                 return ;
  41                         }
  42                         // check for overflow
  43                         if (minSize >= (int.MaxValue / 2))
  44                         {
  45                                 init(int.MaxValue); // wow that's big.
  46                                 return ;
  47                         }
  48                          for (size = 2; size < minSize; size *= 2)
  49                         {
  50                                 ;
  51                         }
  52                         init(size);
  53                 }
  54
  55                 /*Add token to end of the queue
  56                 * @param tok The token to add
  57                 */
  58                 public void  append(IToken tok)
  59                 {
  60                         if (nbrEntries == buffer.Length)
  61                         {
  62                                 expand();
  63                         }
  64                         buffer[(offset + nbrEntries) & sizeLessOne] = tok;
  65                         nbrEntries++;
  66                 }
  67
  68                 /*Fetch a token from the queue by index
  69                 * @param idx The index of the token to fetch, where zero is the token at the front of the queue
  70                 */
  71                 public IToken elementAt(int idx)
  72                 {
  73                         return buffer[(offset + idx) & sizeLessOne];
  74                 }
  75
  76                 /*Expand the token buffer by doubling its capacity */
  77                 private void  expand()
  78                 {
  79                         IToken[] newBuffer = new IToken[buffer.Length * 2];
  80                         // Copy the contents to the new buffer
  81                         // Note that this will store the first logical item in the
  82                         // first physical array element.
  83                          for (int i = 0; i < buffer.Length; i++)
  84                         {
  85                                 newBuffer[i] = elementAt(i);
  86                         }
  87                         // Re-initialize with new contents, keep old nbrEntries
  88                         buffer = newBuffer;
  89                         sizeLessOne = buffer.Length - 1;
  90                         offset = 0;
  91                 }
  92
  93                 /*Initialize the queue.
  94                 * @param size The initial size of the queue
  95                 */
  96                 private void  init(int size)
  97                 {
  98                         // Allocate buffer
  99                         buffer = new IToken[size];
 100                         // Other initialization
 101                         sizeLessOne = size - 1;
 102                         offset = 0;
 103                         nbrEntries = 0;
 104                 }
 105
 106                 /*Clear the queue. Leaving the previous buffer alone.
 107                 */
 108                 public void  reset()
 109                 {
 110                         offset = 0;
 111                         nbrEntries = 0;
 112                 }
 113
 114                 /*Remove token from front of queue */
 115                 public void  removeFirst()
 116                 {
 117                         offset = (offset + 1) & sizeLessOne;
 118                         nbrEntries--;
 119                 }
 120         }
 121 }