/* Expression parsing and evaluation for plural form selection.
   Copyright (C) 2000-2024 Free Software Foundation, Inc.
   Written by Ulrich Drepper <drepper@cygnus.com>, 2000.

   This program 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.

   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 Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public License
   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */

#ifndef _PLURAL_EXP_H
#define _PLURAL_EXP_H

#ifndef attribute_hidden
# define attribute_hidden
#endif

#ifdef __cplusplus
extern "C" {
#endif


/* Parsing a plural expression.  */

enum expression_operator
{
  /* Without arguments:  */
  var,				/* The variable "n".  */
  num,				/* Decimal number.  */
  /* Unary operators:  */
  lnot,				/* Logical NOT.  */
  /* Binary operators:  */
  mult,				/* Multiplication.  */
  divide,			/* Division.  */
  module,			/* Modulo operation.  */
  plus,				/* Addition.  */
  minus,			/* Subtraction.  */
  less_than,			/* Comparison.  */
  greater_than,			/* Comparison.  */
  less_or_equal,		/* Comparison.  */
  greater_or_equal,		/* Comparison.  */
  equal,			/* Comparison for equality.  */
  not_equal,			/* Comparison for inequality.  */
  land,				/* Logical AND.  */
  lor,				/* Logical OR.  */
  /* Ternary operators:  */
  qmop				/* Question mark operator.  */
};

/* This is the representation of the expressions to determine the
   plural form.  */
struct expression
{
  int nargs;			/* Number of arguments.  */
  enum expression_operator operation;
  union
  {
    unsigned long int num;	/* Number value for `num'.  */
    struct expression *args[3];	/* Up to three arguments.  */
  } val;
};

/* This is the data structure to pass information to the parser and get
   the result in a thread-safe way.  */
struct parse_args
{
  const char *cp;
  struct expression *res;
};


/* Names for the libintl functions are a problem.  This source code is used
   1. in the GNU C Library library,
   2. in the GNU libintl library,
   3. in the GNU gettext tools.
   The function names in each situation must be different, to allow for
   binary incompatible changes in 'struct expression'.  Furthermore,
   1. in the GNU C Library library, the names have a __ prefix,
   2.+3. in the GNU libintl library and in the GNU gettext tools, the names
         must follow ANSI C and not start with __.
   So we have to distinguish the three cases.  */
#ifdef _LIBC
# define FREE_EXPRESSION __gettext_free_exp
# define PLURAL_PARSE __gettextparse
# define GERMANIC_PLURAL __gettext_germanic_plural
# define EXTRACT_PLURAL_EXPRESSION __gettext_extract_plural
#elif defined (IN_LIBINTL)
# define FREE_EXPRESSION _libintl_gettext_free_exp
# define PLURAL_PARSE _libintl_gettextparse
# define GERMANIC_PLURAL _libintl_gettext_germanic_plural
# define EXTRACT_PLURAL_EXPRESSION _libintl_gettext_extract_plural
#else
# define FREE_EXPRESSION free_plural_expression
# define PLURAL_PARSE parse_plural_expression
# define GERMANIC_PLURAL germanic_plural
# define EXTRACT_PLURAL_EXPRESSION extract_plural_expression
#endif

extern void FREE_EXPRESSION (struct expression *exp) attribute_hidden;
extern int PLURAL_PARSE (struct parse_args *arg);
extern const struct expression GERMANIC_PLURAL attribute_hidden;
extern void EXTRACT_PLURAL_EXPRESSION (const char *nullentry,
				       const struct expression **pluralp,
				       unsigned long int *npluralsp)
     attribute_hidden;


/* Evaluating a parsed plural expression.  */

enum eval_status
{
  PE_OK,        /* Evaluation succeeded, produced a value */
  PE_INTDIV,    /* Integer division by zero */
  PE_INTOVF,    /* Integer overflow */
  PE_STACKOVF,  /* Stack overflow */
  PE_ASSERT     /* Assertion failure */
};

struct eval_result
{
  enum eval_status status;
  unsigned long int value;      /* Only relevant for status == PE_OK */
};

#if !defined (_LIBC) && !defined (IN_LIBINTL)
extern struct eval_result plural_eval (const struct expression *pexp,
				       unsigned long int n);
#endif


#ifdef __cplusplus
}
#endif

#endif /* _PLURAL_EXP_H */
