/* sexp-parse.h - S-Exp helper functions
 *	Copyright (C) 2002 Free Software Foundation, Inc.
 *
 * This file is part of GnuPG.
 *
 * GnuPG is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * GnuPG 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
 */

#ifndef SEXP_PARSE_H
#define SEXP_PARSE_H

#include "../common/util.h"

/* Return the length of the next S-Exp part and update the pointer to
   the first data byte.  0 is return on error */
static inline size_t
snext (unsigned char const **buf)
{
  const unsigned char *s;
  int n;

  s = *buf;
  for (n=0; *s && *s != ':' && digitp (s); s++)
    n = n*10 + atoi_1 (s);
  if (!n || *s != ':')
    return 0; /* we don't allow empty lengths */
  *buf = s+1;
  return n;
}

/* Skip over the S-Expression BUF points to and update BUF to point to
   the chacter right behind.  DEPTH gives the initial number of open
   lists and may be passed as a positive number to skip over the
   remainder of an S-Expression if the current position is somewhere
   in an S-Expression.  The function may return an error code if it
   encounters an impossible conditions */
static inline int
sskip (unsigned char const **buf, int *depth)
{
  const unsigned char *s = *buf;
  size_t n;
  int d = *depth;
  
  while (d > 0)
    {
      if (*s == '(')
        {
          d++;
          s++;
        }
      else if (*s == ')')
        {
          d--;
          s++;
        }
      else
        {
          if (!d)
            return gpg_error (GPG_ERR_INV_SEXP);
          n = snext (&s);
          if (!n)
            return gpg_error (GPG_ERR_INV_SEXP); 
          s += n;
        }
    }
  *buf = s;
  *depth = d;
  return 0;
}


/* Check whether the the string at the address BUF points to matches
   the token.  Return true on match and update BUF to point behind the
   token. */
static inline int
smatch (unsigned char const **buf, size_t buflen, const char *token)
{
  size_t toklen = strlen (token);

  if (buflen != toklen || memcmp (*buf, token, toklen))
    return 0;
  *buf += toklen;
  return 1;
}

#endif /*SEXP_PARSE_H*/