[bison.git] / src / lalr.h

/* Compute look-ahead criteria for bison,
   Copyright (C) 1984, 1986, 1989 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_


/* Import the definition of CORE, SHIFTS and REDUCTIONS. */
# include "state.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] is the state number which a transition leads from and
   to_state[t] is the 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 short *from_state;
extern short *to_state;

/* CONSISTENT[S] is nonzero if no lookahead is needed to decide what
   to do in state S.  */

extern char *consistent;


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

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

extern short *LAruleno;

/* 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 unsigned *LA;


extern int tokensetsize;
extern short *lookaheads;
extern short *accessing_symbol;
extern core **state_table;
extern shifts **shift_table;
extern reductions **reduction_table;


#endif /* !LALR_H_ */
Commit	Line	Data
720d742f AD	1	/* Compute look-ahead criteria for bison,
	2	Copyright (C) 1984, 1986, 1989 Free Software Foundation, Inc.
	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
a70083a3 AD	24
	25	/* Import the definition of CORE, SHIFTS and REDUCTIONS. */
	26	# include "state.h"
	27
	28
720d742f AD	29	/* Compute how to make the finite state machine deterministic; find
	30	which rules need lookahead in each state, and which lookahead
	31	tokens they accept. */
	32
	33	void lalr PARAMS ((void));
	34
	35
	36	/* lalr() builds these data structures. */
	37
	38	/* goto_map, from_state and to_state --record each shift transition
	39	which accepts a variable (a nonterminal).
	40
	41	from_state[t] is the state number which a transition leads from and
	42	to_state[t] is the state number it leads to. All the transitions
	43	that accept a particular variable are grouped together and
	44	goto_map[i - ntokens] is the index in from_state and to_state of
	45	the first of them. */
	46
	47	extern short *goto_map;
	48	extern short *from_state;
	49	extern short *to_state;
	50
	51	/* CONSISTENT[S] is nonzero if no lookahead is needed to decide what
	52	to do in state S. */
	53
	54	extern char *consistent;
	55
	56
	57	/* LARULENO is a vector which records the rules that need lookahead in
	58	various states. The elements of LARULENO that apply to state S are
	59	those from LOOKAHEADS[S] through LOOKAHEADS[S+1]-1. Each element
	60	of LARULENO is a rule number.
	61
	62	If LR is the length of LAruleno, then a number from 0 to LR-1 can
	63	specify both a rule and a state where the rule might be applied.
	64	*/
	65
	66	extern short *LAruleno;
	67
	68	/* LA is a lr by ntokens matrix of bits. LA[l, i] is 1 if the rule
	69	LAruleno[l] is applicable in the appropriate state when the next
	70	token is symbol i. If LA[l, i] and LA[l, j] are both 1 for i != j,
	71	it is a conflict. */
	72
	73	extern unsigned *LA;
	74
	75
	76	extern int tokensetsize;
	77	extern short *lookaheads;
	78	extern short *accessing_symbol;
	79	extern core **state_table;
	80	extern shifts **shift_table;
	81	extern reductions **reduction_table;
	82
	83
	84
	85	#endif /* !LALR_H_ */