/src/Boo.Lang.Parser/antlr/antlr/TokenQueue.cs
C# | 121 lines | 71 code | 11 blank | 39 comment | 6 complexity | 1a862695ce85f00b82e93d9a6ac78016 MD5 | raw file
Possible License(s): GPL-2.0
- using System;
- namespace antlr
- {
- /*ANTLR Translator Generator
- * Project led by Terence Parr at http://www.jGuru.com
- * Software rights: http://www.antlr.org/license.html
- *
- * $Id:$
- */
- //
- // ANTLR C# Code Generator by Micheal Jordan
- // Kunle Odutola : kunle UNDERSCORE odutola AT hotmail DOT com
- // Anthony Oguntimehin
- //
- // With many thanks to Eric V. Smith from the ANTLR list.
- //
-
- /*A private circular buffer object used by the token buffer */
- class TokenQueue
- {
- /*Physical circular buffer of tokens */
- private IToken[] buffer;
- /*buffer.length-1 for quick modulos */
- private int sizeLessOne;
- /*physical index of front token */
- private int offset;
- /*number of tokens in the queue */
- protected internal int nbrEntries;
-
- public TokenQueue(int minSize)
- {
- // Find first power of 2 >= to requested size
- int size;
- if (minSize < 0)
- {
- init(16); // pick some value for them
- return ;
- }
- // check for overflow
- if (minSize >= (int.MaxValue / 2))
- {
- init(int.MaxValue); // wow that's big.
- return ;
- }
- for (size = 2; size < minSize; size *= 2)
- {
- ;
- }
- init(size);
- }
-
- /*Add token to end of the queue
- * @param tok The token to add
- */
- public void append(IToken tok)
- {
- if (nbrEntries == buffer.Length)
- {
- expand();
- }
- buffer[(offset + nbrEntries) & sizeLessOne] = tok;
- nbrEntries++;
- }
-
- /*Fetch a token from the queue by index
- * @param idx The index of the token to fetch, where zero is the token at the front of the queue
- */
- public IToken elementAt(int idx)
- {
- return buffer[(offset + idx) & sizeLessOne];
- }
-
- /*Expand the token buffer by doubling its capacity */
- private void expand()
- {
- IToken[] newBuffer = new IToken[buffer.Length * 2];
- // Copy the contents to the new buffer
- // Note that this will store the first logical item in the
- // first physical array element.
- for (int i = 0; i < buffer.Length; i++)
- {
- newBuffer[i] = elementAt(i);
- }
- // Re-initialize with new contents, keep old nbrEntries
- buffer = newBuffer;
- sizeLessOne = buffer.Length - 1;
- offset = 0;
- }
-
- /*Initialize the queue.
- * @param size The initial size of the queue
- */
- private void init(int size)
- {
- // Allocate buffer
- buffer = new IToken[size];
- // Other initialization
- sizeLessOne = size - 1;
- offset = 0;
- nbrEntries = 0;
- }
-
- /*Clear the queue. Leaving the previous buffer alone.
- */
- public void reset()
- {
- offset = 0;
- nbrEntries = 0;
- }
-
- /*Remove token from front of queue */
- public void removeFirst()
- {
- offset = (offset + 1) & sizeLessOne;
- nbrEntries--;
- }
- }
- }