using System;
namespace Spring.Expressions.Parser.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 circular buffer object used by CharBuffer */
public class CharQueue
{
/*Physical circular buffer of tokens */
protected internal char[] 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 CharQueue(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 >= (Int32.MaxValue / 2))
{
init(Int32.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(char 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 char elementAt(int idx)
{
return buffer[(offset + idx) & sizeLessOne];
}
/*Expand the token buffer by doubling its capacity */
private void expand()
{
char[] newBuffer = new char[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
*/
public virtual void init(int size)
{
// Allocate buffer
buffer = new char[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 char from front of queue */
public void removeFirst()
{
offset = (offset + 1) & sizeLessOne;
nbrEntries--;
}
}
}
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