src/lalr.c

/* Compute look-ahead criteria for bison,
   Copyright (C) 1984, 1986, 1989, 2000, 2001, 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.  */


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

#include "system.h"
#include "bitset.h"
#include "bitsetv.h"
#include "relation.h"
#include "quotearg.h"
#include "symtab.h"
#include "gram.h"
#include "reader.h"
#include "LR0.h"
#include "complain.h"
#include "lalr.h"
#include "nullable.h"
#include "derives.h"
#include "getargs.h"

goto_number_t *goto_map = NULL;
static goto_number_t ngotos = 0;
state_number_t *from_state = NULL;
state_number_t *to_state = NULL;

/* Linked list of goto numbers.  */
typedef struct goto_list_s
{
  struct goto_list_s *next;
  goto_number_t value;
} goto_list_t;


rule_t **LArule = NULL;
bitsetv LA = NULL;
size_t nLA;


/* And for the famous F variable, which name is so descriptive that a
   comment is hardly needed.  <grin>.  */
static bitsetv F = NULL;

static goto_number_t **includes;
static goto_list_t **lookback;


static void
initialize_LA (void)
{
  state_number_t i;
  int j;
  rule_t **np;

  /* Avoid having to special case 0.  */
  if (!nLA)
    nLA = 1;

  LA = bitsetv_create (nLA, ntokens, BITSET_FIXED);
  LArule = XCALLOC (rule_t *, nLA);
  lookback = XCALLOC (goto_list_t *, nLA);

  np = LArule;
  for (i = 0; i < nstates; i++)
    if (!states[i]->consistent)
      for (j = 0; j < states[i]->reductions->num; j++)
	*np++ = &rules[states[i]->reductions->rules[j]];
}


static void
set_goto_map (void)
{
  state_number_t state;
  goto_number_t *temp_map;

  goto_map = XCALLOC (goto_number_t, nvars + 1) - ntokens;
  temp_map = XCALLOC (goto_number_t, nvars + 1) - ntokens;

  ngotos = 0;
  for (state = 0; state < nstates; ++state)
    {
      transitions_t *sp = states[state]->transitions;
      int i;
      for (i = sp->num - 1; i >= 0 && TRANSITION_IS_GOTO (sp, i); --i)
	{
	  if (ngotos == GOTO_NUMBER_MAX)
	    fatal (_("too many gotos (max %d)"), GOTO_NUMBER_MAX);

	  ngotos++;
	  goto_map[TRANSITION_SYMBOL (sp, i)]++;
	}
    }

  {
    int k = 0;
    int i;
    for (i = ntokens; i < nsyms; i++)
      {
	temp_map[i] = k;
	k += goto_map[i];
      }

    for (i = ntokens; i < nsyms; i++)
      goto_map[i] = temp_map[i];

    goto_map[nsyms] = ngotos;
    temp_map[nsyms] = ngotos;
  }

  from_state = XCALLOC (state_number_t, ngotos);
  to_state = XCALLOC (state_number_t, ngotos);

  for (state = 0; state < nstates; ++state)
    {
      transitions_t *sp = states[state]->transitions;
      int i;
      for (i = sp->num - 1; i >= 0 && TRANSITION_IS_GOTO (sp, i); --i)
	{
	  int k = temp_map[TRANSITION_SYMBOL (sp, i)]++;
	  from_state[k] = state;
	  to_state[k] = sp->states[i];
	}
    }

  XFREE (temp_map + ntokens);
}


/*----------------------------------------------------------.
| Map a state/symbol pair into its numeric representation.  |
`----------------------------------------------------------*/

static int
map_goto (state_number_t state, symbol_number_t symbol)
{
  int high;
  int low;
  int middle;
  state_number_t s;

  low = goto_map[symbol];
  high = goto_map[symbol + 1] - 1;

  while (low <= high)
    {
      middle = (low + high) / 2;
      s = from_state[middle];
      if (s == state)
	return middle;
      else if (s < state)
	low = middle + 1;
      else
	high = middle - 1;
    }

  assert (0);
  /* NOTREACHED */
  return 0;
}


static void
initialize_F (void)
{
  goto_number_t **reads = XCALLOC (goto_number_t *, ngotos);
  goto_number_t *edge = XCALLOC (goto_number_t, ngotos + 1);
  int nedges = 0;

  int i;

  F = bitsetv_create (ngotos, ntokens, BITSET_FIXED);

  for (i = 0; i < ngotos; i++)
    {
      state_number_t stateno = to_state[i];
      transitions_t *sp = states[stateno]->transitions;

      int j;
      for (j = 0; j < sp->num && TRANSITION_IS_SHIFT (sp, j); j++)
	bitset_set (F[i], TRANSITION_SYMBOL (sp, j));

      for (; j < sp->num; j++)
	{
	  symbol_number_t symbol = TRANSITION_SYMBOL (sp, j);
	  if (nullable[symbol])
	    edge[nedges++] = map_goto (stateno, symbol);
	}

      if (nedges)
	{
	  reads[i] = XCALLOC (goto_number_t, nedges + 1);
	  memcpy (reads[i], edge, nedges * sizeof (edge[0]));
	  reads[i][nedges] = -1;
	  nedges = 0;
	}
    }

  relation_digraph (reads, ngotos, &F);

  for (i = 0; i < ngotos; i++)
    XFREE (reads[i]);

  XFREE (reads);
  XFREE (edge);
}


static void
add_lookback_edge (state_t *state, rule_number_t ruleno, int gotono)
{
  int i;
  goto_list_t *sp;

  for (i = 0; i < state->nlookaheads; ++i)
    if (state->lookaheads_rule[i]->number == ruleno)
      break;

  assert (state->lookaheads_rule[i]->number == ruleno);

  sp = XCALLOC (goto_list_t, 1);
  sp->next = lookback[(state->lookaheads - LA) + i];
  sp->value = gotono;
  lookback[(state->lookaheads - LA) + i] = sp;
}


static void
build_relations (void)
{
  goto_number_t *edge = XCALLOC (goto_number_t, ngotos + 1);
  state_number_t *states1 = XCALLOC (state_number_t, ritem_longest_rhs () + 1);
  int i;

  includes = XCALLOC (goto_number_t *, ngotos);

  for (i = 0; i < ngotos; i++)
    {
      int nedges = 0;
      symbol_number_t symbol1 = states[to_state[i]]->accessing_symbol;
      rule_number_t *rulep;

      for (rulep = derives[symbol1]; *rulep > 0; rulep++)
	{
	  int done;
	  int length = 1;
	  item_number_t *rp;
	  state_t *state = states[from_state[i]];
	  states1[0] = state->number;

	  for (rp = rules[*rulep].rhs; *rp >= 0; rp++)
	    {
	      state = transitions_to (state->transitions,
				      item_number_as_symbol_number (*rp));
	      states1[length++] = state->number;
	    }

	  if (!state->consistent)
	    add_lookback_edge (state, *rulep, i);

	  length--;
	  done = 0;
	  while (!done)
	    {
	      done = 1;
	      rp--;
	      /* JF added rp>=ritem &&   I hope to god its right! */
	      if (rp >= ritem && ISVAR (*rp))
		{
		  /* Downcasting from item_number_t to symbol_number_t. */
		  edge[nedges++] = map_goto (states1[--length],
					     item_number_as_symbol_number (*rp));
		  if (nullable[*rp])
		    done = 0;
		}
	    }
	}

      if (nedges)
	{
	  int j;
	  includes[i] = XCALLOC (goto_number_t, nedges + 1);
	  for (j = 0; j < nedges; j++)
	    includes[i][j] = edge[j];
	  includes[i][nedges] = -1;
	}
    }

  XFREE (edge);
  XFREE (states1);

  relation_transpose (&includes, ngotos);
}


static void
compute_FOLLOWS (void)
{
  int i;

  relation_digraph (includes, ngotos, &F);

  for (i = 0; i < ngotos; i++)
    XFREE (includes[i]);

  XFREE (includes);
}


static void
compute_lookaheads (void)
{
  size_t i;
  goto_list_t *sp;

  for (i = 0; i < nLA; i++)
    for (sp = lookback[i]; sp; sp = sp->next)
      bitset_or (LA[i], LA[i], F[sp->value]);

  /* Free LOOKBACK. */
  for (i = 0; i < nLA; i++)
    LIST_FREE (goto_list_t, lookback[i]);

  XFREE (lookback);
  bitsetv_free (F);
}


/*-------------------------------------------------------------.
| Count the number of lookaheads required for each state       |
| (NLOOKAHEADS member).  Compute the total number of LA, NLA.  |
`-------------------------------------------------------------*/

static void
states_lookaheads_count (void)
{
  state_number_t i;
  nLA = 0;

  /* Count   */
  for (i = 0; i < nstates; i++)
    {
      int k;
      int nlookaheads = 0;
      reductions_t *rp = states[i]->reductions;
      transitions_t *sp = states[i]->transitions;

      /* We need a lookahead either to distinguish different
	 reductions (i.e., there are two or more), or to distinguish a
	 reduction from a shift.  Otherwise, it is straightforward,
	 and the state is `consistent'.  */
      if (rp->num > 1
	  || (rp->num == 1 && sp->num && TRANSITION_IS_SHIFT (sp, 0)))
	nlookaheads += rp->num;
      else
	states[i]->consistent = 1;

      for (k = 0; k < sp->num; k++)
	if (TRANSITION_IS_ERROR (sp, k))
	  {
	    states[i]->consistent = 0;
	    break;
	  }

      states[i]->nlookaheads = nlookaheads;
      nLA += nlookaheads;
    }
}


/*--------------------------------------.
| Initializing the lookaheads members.  |
`--------------------------------------*/

static void
states_lookaheads_initialize (void)
{
  state_number_t i;
  bitsetv pLA = LA;
  rule_t **pLArule = LArule;

  /* Initialize the members LOOKAHEADS and LOOKAHEADS_RULE for each
     state.  */
  for (i = 0; i < nstates; i++)
    {
      states[i]->lookaheads = pLA;
      states[i]->lookaheads_rule = pLArule;
      pLA += states[i]->nlookaheads;
      pLArule += states[i]->nlookaheads;
    }
}


/*---------------------------------------.
| Output the lookaheads for each state.  |
`---------------------------------------*/

static void
lookaheads_print (FILE *out)
{
  state_number_t i;
  int j, k;
  fprintf (out, "Lookaheads: BEGIN\n");
  for (i = 0; i < nstates; ++i)
    {
      bitset_iterator iter;

      fprintf (out, "State %d: %d lookaheads\n",
	       i, states[i]->nlookaheads);

      for (j = 0; j < states[i]->nlookaheads; ++j)
	BITSET_FOR_EACH (iter, states[i]->lookaheads[j], k, 0)
	{
	  fprintf (out, "   on %d (%s) -> rule %d\n",
		   k, symbols[k]->tag,
		   states[i]->lookaheads_rule[j]->number - 1);
	};
    }
  fprintf (out, "Lookaheads: END\n");
}

void
lalr (void)
{
  states_lookaheads_count ();
  initialize_LA ();
  states_lookaheads_initialize ();
  set_goto_map ();
  initialize_F ();
  build_relations ();
  compute_FOLLOWS ();
  compute_lookaheads ();

  if (trace_flag)
    lookaheads_print (stderr);
}
Commit	Line	Data
	1	/* Compute look-ahead criteria for bison,
	2	Copyright (C) 1984, 1986, 1989, 2000, 2001, 2002
	3	Free Software Foundation, Inc.
	4
	5	This file is part of Bison, the GNU Compiler Compiler.
	6
	7	Bison is free software; you can redistribute it and/or modify
	8	it under the terms of the GNU General Public License as published by
	9	the Free Software Foundation; either version 2, or (at your option)
	10	any later version.
	11
	12	Bison is distributed in the hope that it will be useful,
	13	but WITHOUT ANY WARRANTY; without even the implied warranty of
	14	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	15	GNU General Public License for more details.
	16
	17	You should have received a copy of the GNU General Public License
	18	along with Bison; see the file COPYING. If not, write to
	19	the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
	20	Boston, MA 02111-1307, USA. */
	21
	22
	23	/* Compute how to make the finite state machine deterministic; find
	24	which rules need lookahead in each state, and which lookahead
	25	tokens they accept. */
	26
	27	#include "system.h"
	28	#include "bitset.h"
	29	#include "bitsetv.h"
	30	#include "relation.h"
	31	#include "quotearg.h"
	32	#include "symtab.h"
	33	#include "gram.h"
	34	#include "reader.h"
	35	#include "LR0.h"
	36	#include "complain.h"
	37	#include "lalr.h"
	38	#include "nullable.h"
	39	#include "derives.h"
	40	#include "getargs.h"
	41
	42	goto_number_t *goto_map = NULL;
	43	static goto_number_t ngotos = 0;
	44	state_number_t *from_state = NULL;
	45	state_number_t *to_state = NULL;
	46
	47	/* Linked list of goto numbers. */
	48	typedef struct goto_list_s
	49	{
	50	struct goto_list_s *next;
	51	goto_number_t value;
	52	} goto_list_t;
	53
	54
	55	rule_t **LArule = NULL;
	56	bitsetv LA = NULL;
	57	size_t nLA;
	58
	59
	60	/* And for the famous F variable, which name is so descriptive that a
	61	comment is hardly needed. <grin>. */
	62	static bitsetv F = NULL;
	63
	64	static goto_number_t **includes;
	65	static goto_list_t **lookback;
	66
	67
	68
	69
	70	static void
	71	initialize_LA (void)
	72	{
	73	state_number_t i;
	74	int j;
	75	rule_t **np;
	76
	77	/* Avoid having to special case 0. */
	78	if (!nLA)
	79	nLA = 1;
	80
	81	LA = bitsetv_create (nLA, ntokens, BITSET_FIXED);
	82	LArule = XCALLOC (rule_t *, nLA);
	83	lookback = XCALLOC (goto_list_t *, nLA);
	84
	85	np = LArule;
	86	for (i = 0; i < nstates; i++)
	87	if (!states[i]->consistent)
	88	for (j = 0; j < states[i]->reductions->num; j++)
	89	*np++ = &rules[states[i]->reductions->rules[j]];
	90	}
	91
	92
	93	static void
	94	set_goto_map (void)
	95	{
	96	state_number_t state;
	97	goto_number_t *temp_map;
	98
	99	goto_map = XCALLOC (goto_number_t, nvars + 1) - ntokens;
	100	temp_map = XCALLOC (goto_number_t, nvars + 1) - ntokens;
	101
	102	ngotos = 0;
	103	for (state = 0; state < nstates; ++state)
	104	{
	105	transitions_t *sp = states[state]->transitions;
	106	int i;
	107	for (i = sp->num - 1; i >= 0 && TRANSITION_IS_GOTO (sp, i); --i)
	108	{
	109	if (ngotos == GOTO_NUMBER_MAX)
	110	fatal (_("too many gotos (max %d)"), GOTO_NUMBER_MAX);
	111
	112	ngotos++;
	113	goto_map[TRANSITION_SYMBOL (sp, i)]++;
	114	}
	115	}
	116
	117	{
	118	int k = 0;
	119	int i;
	120	for (i = ntokens; i < nsyms; i++)
	121	{
	122	temp_map[i] = k;
	123	k += goto_map[i];
	124	}
	125
	126	for (i = ntokens; i < nsyms; i++)
	127	goto_map[i] = temp_map[i];
	128
	129	goto_map[nsyms] = ngotos;
	130	temp_map[nsyms] = ngotos;
	131	}
	132
	133	from_state = XCALLOC (state_number_t, ngotos);
	134	to_state = XCALLOC (state_number_t, ngotos);
	135
	136	for (state = 0; state < nstates; ++state)
	137	{
	138	transitions_t *sp = states[state]->transitions;
	139	int i;
	140	for (i = sp->num - 1; i >= 0 && TRANSITION_IS_GOTO (sp, i); --i)
	141	{
	142	int k = temp_map[TRANSITION_SYMBOL (sp, i)]++;
	143	from_state[k] = state;
	144	to_state[k] = sp->states[i];
	145	}
	146	}
	147
	148	XFREE (temp_map + ntokens);
	149	}
	150
	151
	152
	153	/*----------------------------------------------------------.
	154	\| Map a state/symbol pair into its numeric representation. \|
	155	`----------------------------------------------------------*/
	156
	157	static int
	158	map_goto (state_number_t state, symbol_number_t symbol)
	159	{
	160	int high;
	161	int low;
	162	int middle;
	163	state_number_t s;
	164
	165	low = goto_map[symbol];
	166	high = goto_map[symbol + 1] - 1;
	167
	168	while (low <= high)
	169	{
	170	middle = (low + high) / 2;
	171	s = from_state[middle];
	172	if (s == state)
	173	return middle;
	174	else if (s < state)
	175	low = middle + 1;
	176	else
	177	high = middle - 1;
	178	}
	179
	180	assert (0);
	181	/* NOTREACHED */
	182	return 0;
	183	}
	184
	185
	186	static void
	187	initialize_F (void)
	188	{
	189	goto_number_t *reads = XCALLOC (goto_number_t , ngotos);
	190	goto_number_t *edge = XCALLOC (goto_number_t, ngotos + 1);
	191	int nedges = 0;
	192
	193	int i;
	194
	195	F = bitsetv_create (ngotos, ntokens, BITSET_FIXED);
	196
	197	for (i = 0; i < ngotos; i++)
	198	{
	199	state_number_t stateno = to_state[i];
	200	transitions_t *sp = states[stateno]->transitions;
	201
	202	int j;
	203	for (j = 0; j < sp->num && TRANSITION_IS_SHIFT (sp, j); j++)
	204	bitset_set (F[i], TRANSITION_SYMBOL (sp, j));
	205
	206	for (; j < sp->num; j++)
	207	{
	208	symbol_number_t symbol = TRANSITION_SYMBOL (sp, j);
	209	if (nullable[symbol])
	210	edge[nedges++] = map_goto (stateno, symbol);
	211	}
	212
	213	if (nedges)
	214	{
	215	reads[i] = XCALLOC (goto_number_t, nedges + 1);
	216	memcpy (reads[i], edge, nedges * sizeof (edge[0]));
	217	reads[i][nedges] = -1;
	218	nedges = 0;
	219	}
	220	}
	221
	222	relation_digraph (reads, ngotos, &F);
	223
	224	for (i = 0; i < ngotos; i++)
	225	XFREE (reads[i]);
	226
	227	XFREE (reads);
	228	XFREE (edge);
	229	}
	230
	231
	232	static void
	233	add_lookback_edge (state_t *state, rule_number_t ruleno, int gotono)
	234	{
	235	int i;
	236	goto_list_t *sp;
	237
	238	for (i = 0; i < state->nlookaheads; ++i)
	239	if (state->lookaheads_rule[i]->number == ruleno)
	240	break;
	241
	242	assert (state->lookaheads_rule[i]->number == ruleno);
	243
	244	sp = XCALLOC (goto_list_t, 1);
	245	sp->next = lookback[(state->lookaheads - LA) + i];
	246	sp->value = gotono;
	247	lookback[(state->lookaheads - LA) + i] = sp;
	248	}
	249
	250
	251
	252	static void
	253	build_relations (void)
	254	{
	255	goto_number_t *edge = XCALLOC (goto_number_t, ngotos + 1);
	256	state_number_t *states1 = XCALLOC (state_number_t, ritem_longest_rhs () + 1);
	257	int i;
	258
	259	includes = XCALLOC (goto_number_t *, ngotos);
	260
	261	for (i = 0; i < ngotos; i++)
	262	{
	263	int nedges = 0;
	264	symbol_number_t symbol1 = states[to_state[i]]->accessing_symbol;
	265	rule_number_t *rulep;
	266
	267	for (rulep = derives[symbol1]; *rulep > 0; rulep++)
	268	{
	269	int done;
	270	int length = 1;
	271	item_number_t *rp;
	272	state_t *state = states[from_state[i]];
	273	states1[0] = state->number;
	274
	275	for (rp = rules[rulep].rhs; rp >= 0; rp++)
	276	{
	277	state = transitions_to (state->transitions,
	278	item_number_as_symbol_number (*rp));
	279	states1[length++] = state->number;
	280	}
	281
	282	if (!state->consistent)
	283	add_lookback_edge (state, *rulep, i);
	284
	285	length--;
	286	done = 0;
	287	while (!done)
	288	{
	289	done = 1;
	290	rp--;
	291	/* JF added rp>=ritem && I hope to god its right! */
	292	if (rp >= ritem && ISVAR (*rp))
	293	{
	294	/* Downcasting from item_number_t to symbol_number_t. */
	295	edge[nedges++] = map_goto (states1[--length],
	296	item_number_as_symbol_number (*rp));
	297	if (nullable[*rp])
	298	done = 0;
	299	}
	300	}
	301	}
	302
	303	if (nedges)
	304	{
	305	int j;
	306	includes[i] = XCALLOC (goto_number_t, nedges + 1);
	307	for (j = 0; j < nedges; j++)
	308	includes[i][j] = edge[j];
	309	includes[i][nedges] = -1;
	310	}
	311	}
	312
	313	XFREE (edge);
	314	XFREE (states1);
	315
	316	relation_transpose (&includes, ngotos);
	317	}
	318
	319
	320
	321	static void
	322	compute_FOLLOWS (void)
	323	{
	324	int i;
	325
	326	relation_digraph (includes, ngotos, &F);
	327
	328	for (i = 0; i < ngotos; i++)
	329	XFREE (includes[i]);
	330
	331	XFREE (includes);
	332	}
	333
	334
	335	static void
	336	compute_lookaheads (void)
	337	{
	338	size_t i;
	339	goto_list_t *sp;
	340
	341	for (i = 0; i < nLA; i++)
	342	for (sp = lookback[i]; sp; sp = sp->next)
	343	bitset_or (LA[i], LA[i], F[sp->value]);
	344
	345	/* Free LOOKBACK. */
	346	for (i = 0; i < nLA; i++)
	347	LIST_FREE (goto_list_t, lookback[i]);
	348
	349	XFREE (lookback);
	350	bitsetv_free (F);
	351	}
	352
	353
	354	/*-------------------------------------------------------------.
	355	\| Count the number of lookaheads required for each state \|
	356	\| (NLOOKAHEADS member). Compute the total number of LA, NLA. \|
	357	`-------------------------------------------------------------*/
	358
	359	static void
	360	states_lookaheads_count (void)
	361	{
	362	state_number_t i;
	363	nLA = 0;
	364
	365	/* Count */
	366	for (i = 0; i < nstates; i++)
	367	{
	368	int k;
	369	int nlookaheads = 0;
	370	reductions_t *rp = states[i]->reductions;
	371	transitions_t *sp = states[i]->transitions;
	372
	373	/* We need a lookahead either to distinguish different
	374	reductions (i.e., there are two or more), or to distinguish a
	375	reduction from a shift. Otherwise, it is straightforward,
	376	and the state is `consistent'. */
	377	if (rp->num > 1
	378	\|\| (rp->num == 1 && sp->num && TRANSITION_IS_SHIFT (sp, 0)))
	379	nlookaheads += rp->num;
	380	else
	381	states[i]->consistent = 1;
	382
	383	for (k = 0; k < sp->num; k++)
	384	if (TRANSITION_IS_ERROR (sp, k))
	385	{
	386	states[i]->consistent = 0;
	387	break;
	388	}
	389
	390	states[i]->nlookaheads = nlookaheads;
	391	nLA += nlookaheads;
	392	}
	393	}
	394
	395
	396	/*--------------------------------------.
	397	\| Initializing the lookaheads members. \|
	398	`--------------------------------------*/
	399
	400	static void
	401	states_lookaheads_initialize (void)
	402	{
	403	state_number_t i;
	404	bitsetv pLA = LA;
	405	rule_t **pLArule = LArule;
	406
	407	/* Initialize the members LOOKAHEADS and LOOKAHEADS_RULE for each
	408	state. */
	409	for (i = 0; i < nstates; i++)
	410	{
	411	states[i]->lookaheads = pLA;
	412	states[i]->lookaheads_rule = pLArule;
	413	pLA += states[i]->nlookaheads;
	414	pLArule += states[i]->nlookaheads;
	415	}
	416	}
	417
	418
	419	/*---------------------------------------.
	420	\| Output the lookaheads for each state. \|
	421	`---------------------------------------*/
	422
	423	static void
	424	lookaheads_print (FILE *out)
	425	{
	426	state_number_t i;
	427	int j, k;
	428	fprintf (out, "Lookaheads: BEGIN\n");
	429	for (i = 0; i < nstates; ++i)
	430	{
	431	bitset_iterator iter;
	432
	433	fprintf (out, "State %d: %d lookaheads\n",
	434	i, states[i]->nlookaheads);
	435
	436	for (j = 0; j < states[i]->nlookaheads; ++j)
	437	BITSET_FOR_EACH (iter, states[i]->lookaheads[j], k, 0)
	438	{
	439	fprintf (out, " on %d (%s) -> rule %d\n",
	440	k, symbols[k]->tag,
	441	states[i]->lookaheads_rule[j]->number - 1);
	442	};
	443	}
	444	fprintf (out, "Lookaheads: END\n");
	445	}
	446
	447	void
	448	lalr (void)
	449	{
	450	states_lookaheads_count ();
	451	initialize_LA ();
	452	states_lookaheads_initialize ();
	453	set_goto_map ();
	454	initialize_F ();
	455	build_relations ();
	456	compute_FOLLOWS ();
	457	compute_lookaheads ();
	458
	459	if (trace_flag)
	460	lookaheads_print (stderr);
	461	}