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/* Plural expression evaluation.
Copyright (C) 2000-2002 Free Software Foundation, Inc.
This program 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, or (at your option)
any later version.
This program 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 program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301,
USA. */
#ifndef STATIC
#define STATIC static
#endif
/* Evaluate the plural expression and return an index value. */
STATIC unsigned long int plural_eval PARAMS ((struct expression *pexp,
unsigned long int n))
internal_function;
STATIC
unsigned long int
internal_function
plural_eval (pexp, n)
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:
#if !INTDIV0_RAISES_SIGFPE
if (rightarg == 0)
raise (SIGFPE);
#endif
return leftarg / rightarg;
case module:
#if !INTDIV0_RAISES_SIGFPE
if (rightarg == 0)
raise (SIGFPE);
#endif
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;
}
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