/* Plural expression evaluation.
   Copyright (C) 2000, 2001, 2007 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

static unsigned long int plural_eval (const struct expression *pexp,
				      unsigned long int n)
     internal_function;

static unsigned long int
internal_function
plural_eval (pexp, n)
     const struct expression *pexp;
     unsigned long int n;
{
  switch (pexp->nargs)
    {
    case 0:
      switch (pexp->operation)
	{
	case var:
	  return n;
	case num:
	  return pexp->val.num;
	default:
	  break;
	}
      /* NOTREACHED */
      break;
    case 1:
      {
	/* pexp->operation must be lnot.  */
	unsigned long int arg = plural_eval (pexp->val.args[0], n);
	return ! arg;
      }
    case 2:
      {
	unsigned long int leftarg = plural_eval (pexp->val.args[0], n);
	if (pexp->operation == lor)
	  return leftarg || plural_eval (pexp->val.args[1], n);
	else if (pexp->operation == land)
	  return leftarg && plural_eval (pexp->val.args[1], n);
	else
	  {
	    unsigned long int rightarg = plural_eval (pexp->val.args[1], n);

	    switch (pexp->operation)
	      {
	      case mult:
		return leftarg * rightarg;
	      case divide:
		return leftarg / rightarg;
	      case module:
		return leftarg % rightarg;
	      case plus:
		return leftarg + rightarg;
	      case minus:
		return leftarg - rightarg;
	      case less_than:
		return leftarg < rightarg;
	      case greater_than:
		return leftarg > rightarg;
	      case less_or_equal:
		return leftarg <= rightarg;
	      case greater_or_equal:
		return leftarg >= rightarg;
	      case equal:
		return leftarg == rightarg;
	      case not_equal:
		return leftarg != rightarg;
	      default:
		break;
	      }
	  }
	/* NOTREACHED */
	break;
      }
    case 3:
      {
	/* pexp->operation must be qmop.  */
	unsigned long int boolarg = plural_eval (pexp->val.args[0], n);
	return plural_eval (pexp->val.args[boolarg ? 1 : 2], n);
      }
    }
  /* NOTREACHED */
  return 0;
}