// This may look like C code, but it is really -*- C++ -*-
/* 
Copyright (C) 1989 Free Software Foundation
    written by Doug Lea (dl@rocky.oswego.edu)

This file is part of the GNU C++ Library.  This library is free
software; you can redistribute it and/or modify it under the terms of
the GNU Library General Public License as published by the Free
Software Foundation; either version 2 of the License, or (at your
option) any later version.  This library is distributed in the hope
that it will be useful, but WITHOUT ANY WARRANTY; without even the
implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE.  See the GNU Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with this library; if not, write to the Free Software
Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
*/


#ifndef _AllocRing_h
#ifdef __GNUG__
#pragma interface
#endif
#define _AllocRing_h 1


/*
 * dl/per: the typing for sizes in this entire lib really sucks man!
 * it really screws us on the atari where:
 *    size_t != long != (necessarily) int != short
 *
 * yeah, yeah, i know i should'nt be complaining free software and all that
 * jazz, but this is even asthetically displeasing: having a signed type for
 * sizes firstly restricts the size (try int == 16 bits), and secondly
 * it cuts out the possibility of catching silly error where the size
 * is or becomes negative.
 *
 *  ++jrb
 */


/*
  An AllocRing holds the last n malloc'ed strings, reallocating/reusing 
  one only when the queue wraps around. It thus guarantees that the
  last n allocations are intact. It is useful for things like I/O
  formatting where reasonable restrictions may be made about the
  number of allowable live allocations before auto-deletion.
*/

class AllocRing
{

  struct AllocQNode
  {
    void*  ptr;
    size_t sz;
  };

  AllocQNode* nodes;
  size_t      n;
  size_t      current;

  long        find(void* p);

public:

              AllocRing(size_t max);
             ~AllocRing();

  void*       alloc(size_t size);
  int         contains(void* ptr);
  void        clear();
  void        free(void* p);
};


#endif