[bison.git] / src / lalr.h

/* Compute look-ahead criteria for bison,
   Copyright (C) 1984, 1986, 1989, 2000, 2002 Free Software Foundation, Inc.

   This file is part of Bison, the GNU Compiler Compiler.

   Bison 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, or (at your option)
   any later version.

   Bison 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 Bison; see the file COPYING.  If not, write to
   the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#ifndef LALR_H_
# define LALR_H_

#include "bitset.h"
#include "bitsetv.h"

/* Import the definition of CORE, SHIFTS and REDUCTIONS. */
# include "state.h"

/* Import the definition of RULE_T. */
# include "gram.h"

/* Compute how to make the finite state machine deterministic; find
   which rules need lookahead in each state, and which lookahead
   tokens they accept.  */

void lalr PARAMS ((void));


/* lalr() builds these data structures. */

/* GOTO_MAP, FROM_STATE and TO_STATE -- record each shift transition
   which accepts a variable (a nonterminal).

   FROM_STATE[T] -- state number which a transition leads from.
   TO_STATE[T] -- state number it leads to.

   All the transitions that accept a particular variable are grouped
   together and GOTO_MAP[I - NTOKENS] is the index in FROM_STATE and
   TO_STATE of the first of them.  */

extern short *goto_map;
extern state_number_t *from_state;
extern state_number_t *to_state;

/* LARULE is a vector which records the rules that need lookahead in
   various states.  The elements of LARULE that apply to state S are
   those from LOOKAHEADS[S] through LOOKAHEADS[S+1]-1.

   If LR is the length of LArule, then a number from 0 to LR-1 can
   specify both a rule and a state where the rule might be applied.
   */

extern rule_t **LArule;

/* LA is a LR by NTOKENS matrix of bits.  LA[l, i] is 1 if the rule
   LAruleno[l] is applicable in the appropriate state when the next
   token is symbol i.  If LA[l, i] and LA[l, j] are both 1 for i != j,
   it is a conflict.  */

extern bitsetv LA;


#endif /* !LALR_H_ */
Commit	Line	Data
720d742f	1	/* Compute look-ahead criteria for bison,
b0299a2e	2	Copyright (C) 1984, 1986, 1989, 2000, 2002 Free Software Foundation, Inc.
720d742f AD	3
	4	This file is part of Bison, the GNU Compiler Compiler.
	5
	6	Bison is free software; you can redistribute it and/or modify
	7	it under the terms of the GNU General Public License as published by
	8	the Free Software Foundation; either version 2, or (at your option)
	9	any later version.
	10
	11	Bison is distributed in the hope that it will be useful,
	12	but WITHOUT ANY WARRANTY; without even the implied warranty of
	13	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	14	GNU General Public License for more details.
	15
	16	You should have received a copy of the GNU General Public License
	17	along with Bison; see the file COPYING. If not, write to
	18	the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
	19	Boston, MA 02111-1307, USA. */
	20
	21	#ifndef LALR_H_
	22	# define LALR_H_
	23
602bbf31	24	#include "bitset.h"
e601aa1d	25	#include "bitsetv.h"
a70083a3 AD	26
	27	/* Import the definition of CORE, SHIFTS and REDUCTIONS. */
	28	# include "state.h"
	29
b0299a2e AD	30	/* Import the definition of RULE_T. */
b0299a2e AD	31	# include "gram.h"
a70083a3	32
720d742f AD	33	/* Compute how to make the finite state machine deterministic; find
	34	which rules need lookahead in each state, and which lookahead
	35	tokens they accept. */
	36
	37	void lalr PARAMS ((void));
	38
	39
	40	/* lalr() builds these data structures. */
	41
43591cec	42	/* GOTO_MAP, FROM_STATE and TO_STATE -- record each shift transition
720d742f AD	43	which accepts a variable (a nonterminal).
720d742f AD	44
43591cec AD	45	FROM_STATE[T] -- state number which a transition leads from.
	46	TO_STATE[T] -- state number it leads to.
	47
	48	All the transitions that accept a particular variable are grouped
	49	together and GOTO_MAP[I - NTOKENS] is the index in FROM_STATE and
	50	TO_STATE of the first of them. */
720d742f AD	51
720d742f AD	52	extern short *goto_map;
d57650a5 AD	53	extern state_number_t *from_state;
d57650a5 AD	54	extern state_number_t *to_state;
720d742f	55
b0299a2e AD	56	/* LARULE is a vector which records the rules that need lookahead in
	57	various states. The elements of LARULE that apply to state S are
	58	those from LOOKAHEADS[S] through LOOKAHEADS[S+1]-1.
720d742f	59
b0299a2e	60	If LR is the length of LArule, then a number from 0 to LR-1 can
720d742f AD	61	specify both a rule and a state where the rule might be applied.
	62	*/
	63
b0299a2e	64	extern rule_t **LArule;
720d742f	65
9801d40c	66	/* LA is a LR by NTOKENS matrix of bits. LA[l, i] is 1 if the rule
720d742f AD	67	LAruleno[l] is applicable in the appropriate state when the next
	68	token is symbol i. If LA[l, i] and LA[l, j] are both 1 for i != j,
	69	it is a conflict. */
	70
e601aa1d	71	extern bitsetv LA;
720d742f AD	72
720d742f AD	73
720d742f	74	#endif /* !LALR_H_ */