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;


/* LA is a LR by NTOKENS matrix of bits.  LA[l, i] is 1 if the rule
   LArule[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.  */

static 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
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]->number;
	}
    }

  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_EACH_SHIFT (sp, 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_t *rule, int gotono)
{
  int r = state_reduction_find (state, rule);
  goto_list_t *sp = XCALLOC (goto_list_t, 1);
  sp->next = lookback[(state->reductions->lookaheads - LA) + r];
  sp->value = gotono;
  lookback[(state->reductions->lookaheads - LA) + r] = 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_t **rulep;

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

	  for (rp = (*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 STATE (NLOOKAHEADS |
| member).                                                       |
`---------------------------------------------------------------*/

static int
state_lookaheads_count (state_t *state)
{
  int k;
  int nlookaheads = 0;
  reductions_t *rp = state->reductions;
  transitions_t *sp = state->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_DISABLED (sp, 0) && TRANSITION_IS_SHIFT (sp, 0)))
    nlookaheads += rp->num;
  else
    state->consistent = 1;

  for (k = 0; k < sp->num; k++)
    if (!TRANSITION_IS_DISABLED (sp, k) && TRANSITION_IS_ERROR (sp, k))
      {
	state->consistent = 0;
	break;
      }

  return nlookaheads;
}


/*----------------------------------------------.
| Compute LA, NLA, and the lookaheads members.  |
`----------------------------------------------*/

static void
initialize_LA (void)
{
  state_number_t i;
  bitsetv pLA;

  /* Compute the total number of reductions requiring a lookahead.  */
  nLA = 0;
  for (i = 0; i < nstates; i++)
    nLA += state_lookaheads_count (states[i]);
  /* Avoid having to special case 0.  */
  if (!nLA)
    nLA = 1;

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

  /* Initialize the members LOOKAHEADS for each state which reductions
     require lookaheads.  */
  for (i = 0; i < nstates; i++)
    {
      int count = state_lookaheads_count (states[i]);
      if (count)
	{
	  states[i]->reductions->lookaheads = pLA;
	  pLA += count;
	}
    }
}


/*---------------------------------------.
| 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)
    {
      reductions_t *reds = states[i]->reductions;
      bitset_iterator iter;
      int nlookaheads = 0;

      if (reds->lookaheads)
	for (k = 0; k < reds->num; ++k)
	  if (reds->lookaheads[k])
	    ++nlookaheads;

      fprintf (out, "State %d: %d lookaheads\n",
	       i, nlookaheads);

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

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

  if (trace_flag & trace_sets)
    lookaheads_print (stderr);
}


void
lalr_free (void)
{
  state_number_t s;
  for (s = 0; s < nstates; ++s)
    states[s]->reductions->lookaheads = NULL;
  bitsetv_free (LA);
}
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	/* LA is a LR by NTOKENS matrix of bits. LA[l, i] is 1 if the rule
	56	LArule[l] is applicable in the appropriate state when the next
	57	token is symbol i. If LA[l, i] and LA[l, j] are both 1 for i != j,
	58	it is a conflict. */
	59
	60	static bitsetv LA = NULL;
	61	size_t nLA;
	62
	63
	64	/* And for the famous F variable, which name is so descriptive that a
	65	comment is hardly needed. <grin>. */
	66	static bitsetv F = NULL;
	67
	68	static goto_number_t **includes;
	69	static goto_list_t **lookback;
	70
	71
	72
	73
	74	static void
	75	set_goto_map (void)
	76	{
	77	state_number_t state;
	78	goto_number_t *temp_map;
	79
	80	goto_map = XCALLOC (goto_number_t, nvars + 1) - ntokens;
	81	temp_map = XCALLOC (goto_number_t, nvars + 1) - ntokens;
	82
	83	ngotos = 0;
	84	for (state = 0; state < nstates; ++state)
	85	{
	86	transitions_t *sp = states[state]->transitions;
	87	int i;
	88	for (i = sp->num - 1; i >= 0 && TRANSITION_IS_GOTO (sp, i); --i)
	89	{
	90	if (ngotos == GOTO_NUMBER_MAX)
	91	fatal (_("too many gotos (max %d)"), GOTO_NUMBER_MAX);
	92
	93	ngotos++;
	94	goto_map[TRANSITION_SYMBOL (sp, i)]++;
	95	}
	96	}
	97
	98	{
	99	int k = 0;
	100	int i;
	101	for (i = ntokens; i < nsyms; i++)
	102	{
	103	temp_map[i] = k;
	104	k += goto_map[i];
	105	}
	106
	107	for (i = ntokens; i < nsyms; i++)
	108	goto_map[i] = temp_map[i];
	109
	110	goto_map[nsyms] = ngotos;
	111	temp_map[nsyms] = ngotos;
	112	}
	113
	114	from_state = XCALLOC (state_number_t, ngotos);
	115	to_state = XCALLOC (state_number_t, ngotos);
	116
	117	for (state = 0; state < nstates; ++state)
	118	{
	119	transitions_t *sp = states[state]->transitions;
	120	int i;
	121	for (i = sp->num - 1; i >= 0 && TRANSITION_IS_GOTO (sp, i); --i)
	122	{
	123	int k = temp_map[TRANSITION_SYMBOL (sp, i)]++;
	124	from_state[k] = state;
	125	to_state[k] = sp->states[i]->number;
	126	}
	127	}
	128
	129	XFREE (temp_map + ntokens);
	130	}
	131
	132
	133
	134	/*----------------------------------------------------------.
	135	\| Map a state/symbol pair into its numeric representation. \|
	136	`----------------------------------------------------------*/
	137
	138	static int
	139	map_goto (state_number_t state, symbol_number_t symbol)
	140	{
	141	int high;
	142	int low;
	143	int middle;
	144	state_number_t s;
	145
	146	low = goto_map[symbol];
	147	high = goto_map[symbol + 1] - 1;
	148
	149	while (low <= high)
	150	{
	151	middle = (low + high) / 2;
	152	s = from_state[middle];
	153	if (s == state)
	154	return middle;
	155	else if (s < state)
	156	low = middle + 1;
	157	else
	158	high = middle - 1;
	159	}
	160
	161	assert (0);
	162	/* NOTREACHED */
	163	return 0;
	164	}
	165
	166
	167	static void
	168	initialize_F (void)
	169	{
	170	goto_number_t *reads = XCALLOC (goto_number_t , ngotos);
	171	goto_number_t *edge = XCALLOC (goto_number_t, ngotos + 1);
	172	int nedges = 0;
	173
	174	int i;
	175
	176	F = bitsetv_create (ngotos, ntokens, BITSET_FIXED);
	177
	178	for (i = 0; i < ngotos; i++)
	179	{
	180	state_number_t stateno = to_state[i];
	181	transitions_t *sp = states[stateno]->transitions;
	182
	183	int j;
	184	FOR_EACH_SHIFT (sp, j)
	185	bitset_set (F[i], TRANSITION_SYMBOL (sp, j));
	186
	187	for (; j < sp->num; j++)
	188	{
	189	symbol_number_t symbol = TRANSITION_SYMBOL (sp, j);
	190	if (nullable[symbol])
	191	edge[nedges++] = map_goto (stateno, symbol);
	192	}
	193
	194	if (nedges)
	195	{
	196	reads[i] = XCALLOC (goto_number_t, nedges + 1);
	197	memcpy (reads[i], edge, nedges * sizeof (edge[0]));
	198	reads[i][nedges] = -1;
	199	nedges = 0;
	200	}
	201	}
	202
	203	relation_digraph (reads, ngotos, &F);
	204
	205	for (i = 0; i < ngotos; i++)
	206	XFREE (reads[i]);
	207
	208	XFREE (reads);
	209	XFREE (edge);
	210	}
	211
	212
	213	static void
	214	add_lookback_edge (state_t state, rule_t rule, int gotono)
	215	{
	216	int r = state_reduction_find (state, rule);
	217	goto_list_t *sp = XCALLOC (goto_list_t, 1);
	218	sp->next = lookback[(state->reductions->lookaheads - LA) + r];
	219	sp->value = gotono;
	220	lookback[(state->reductions->lookaheads - LA) + r] = sp;
	221	}
	222
	223
	224
	225	static void
	226	build_relations (void)
	227	{
	228	goto_number_t *edge = XCALLOC (goto_number_t, ngotos + 1);
	229	state_number_t *states1 = XCALLOC (state_number_t, ritem_longest_rhs () + 1);
	230	int i;
	231
	232	includes = XCALLOC (goto_number_t *, ngotos);
	233
	234	for (i = 0; i < ngotos; i++)
	235	{
	236	int nedges = 0;
	237	symbol_number_t symbol1 = states[to_state[i]]->accessing_symbol;
	238	rule_t **rulep;
	239
	240	for (rulep = derives[symbol1]; *rulep; rulep++)
	241	{
	242	int done;
	243	int length = 1;
	244	item_number_t *rp;
	245	state_t *state = states[from_state[i]];
	246	states1[0] = state->number;
	247
	248	for (rp = (rulep)->rhs; rp >= 0; rp++)
	249	{
	250	state = transitions_to (state->transitions,
	251	item_number_as_symbol_number (*rp));
	252	states1[length++] = state->number;
	253	}
	254
	255	if (!state->consistent)
	256	add_lookback_edge (state, *rulep, i);
	257
	258	length--;
	259	done = 0;
	260	while (!done)
	261	{
	262	done = 1;
	263	rp--;
	264	/* JF added rp>=ritem && I hope to god its right! */
	265	if (rp >= ritem && ISVAR (*rp))
	266	{
	267	/* Downcasting from item_number_t to symbol_number_t. */
	268	edge[nedges++] = map_goto (states1[--length],
	269	item_number_as_symbol_number (*rp));
	270	if (nullable[*rp])
	271	done = 0;
	272	}
	273	}
	274	}
	275
	276	if (nedges)
	277	{
	278	int j;
	279	includes[i] = XCALLOC (goto_number_t, nedges + 1);
	280	for (j = 0; j < nedges; j++)
	281	includes[i][j] = edge[j];
	282	includes[i][nedges] = -1;
	283	}
	284	}
	285
	286	XFREE (edge);
	287	XFREE (states1);
	288
	289	relation_transpose (&includes, ngotos);
	290	}
	291
	292
	293
	294	static void
	295	compute_FOLLOWS (void)
	296	{
	297	int i;
	298
	299	relation_digraph (includes, ngotos, &F);
	300
	301	for (i = 0; i < ngotos; i++)
	302	XFREE (includes[i]);
	303
	304	XFREE (includes);
	305	}
	306
	307
	308	static void
	309	compute_lookaheads (void)
	310	{
	311	size_t i;
	312	goto_list_t *sp;
	313
	314	for (i = 0; i < nLA; i++)
	315	for (sp = lookback[i]; sp; sp = sp->next)
	316	bitset_or (LA[i], LA[i], F[sp->value]);
	317
	318	/* Free LOOKBACK. */
	319	for (i = 0; i < nLA; i++)
	320	LIST_FREE (goto_list_t, lookback[i]);
	321
	322	XFREE (lookback);
	323	bitsetv_free (F);
	324	}
	325
	326
	327	/*---------------------------------------------------------------.
	328	\| Count the number of lookaheads required for STATE (NLOOKAHEADS \|
	329	\| member). \|
	330	`---------------------------------------------------------------*/
	331
	332	static int
	333	state_lookaheads_count (state_t *state)
	334	{
	335	int k;
	336	int nlookaheads = 0;
	337	reductions_t *rp = state->reductions;
	338	transitions_t *sp = state->transitions;
	339
	340	/* We need a lookahead either to distinguish different
	341	reductions (i.e., there are two or more), or to distinguish a
	342	reduction from a shift. Otherwise, it is straightforward,
	343	and the state is `consistent'. */
	344	if (rp->num > 1
	345	\|\| (rp->num == 1 && sp->num &&
	346	!TRANSITION_IS_DISABLED (sp, 0) && TRANSITION_IS_SHIFT (sp, 0)))
	347	nlookaheads += rp->num;
	348	else
	349	state->consistent = 1;
	350
	351	for (k = 0; k < sp->num; k++)
	352	if (!TRANSITION_IS_DISABLED (sp, k) && TRANSITION_IS_ERROR (sp, k))
	353	{
	354	state->consistent = 0;
	355	break;
	356	}
	357
	358	return nlookaheads;
	359	}
	360
	361
	362	/*----------------------------------------------.
	363	\| Compute LA, NLA, and the lookaheads members. \|
	364	`----------------------------------------------*/
	365
	366	static void
	367	initialize_LA (void)
	368	{
	369	state_number_t i;
	370	bitsetv pLA;
	371
	372	/* Compute the total number of reductions requiring a lookahead. */
	373	nLA = 0;
	374	for (i = 0; i < nstates; i++)
	375	nLA += state_lookaheads_count (states[i]);
	376	/* Avoid having to special case 0. */
	377	if (!nLA)
	378	nLA = 1;
	379
	380	pLA = LA = bitsetv_create (nLA, ntokens, BITSET_FIXED);
	381	lookback = XCALLOC (goto_list_t *, nLA);
	382
	383	/* Initialize the members LOOKAHEADS for each state which reductions
	384	require lookaheads. */
	385	for (i = 0; i < nstates; i++)
	386	{
	387	int count = state_lookaheads_count (states[i]);
	388	if (count)
	389	{
	390	states[i]->reductions->lookaheads = pLA;
	391	pLA += count;
	392	}
	393	}
	394	}
	395
	396
	397	/*---------------------------------------.
	398	\| Output the lookaheads for each state. \|
	399	`---------------------------------------*/
	400
	401	static void
	402	lookaheads_print (FILE *out)
	403	{
	404	state_number_t i;
	405	int j, k;
	406	fprintf (out, "Lookaheads: BEGIN\n");
	407	for (i = 0; i < nstates; ++i)
	408	{
	409	reductions_t *reds = states[i]->reductions;
	410	bitset_iterator iter;
	411	int nlookaheads = 0;
	412
	413	if (reds->lookaheads)
	414	for (k = 0; k < reds->num; ++k)
	415	if (reds->lookaheads[k])
	416	++nlookaheads;
	417
	418	fprintf (out, "State %d: %d lookaheads\n",
	419	i, nlookaheads);
	420
	421	if (reds->lookaheads)
	422	for (j = 0; j < reds->num; ++j)
	423	BITSET_FOR_EACH (iter, reds->lookaheads[j], k, 0)
	424	{
	425	fprintf (out, " on %d (%s) -> rule %d\n",
	426	k, symbols[k]->tag,
	427	reds->rules[j]->number);
	428	};
	429	}
	430	fprintf (out, "Lookaheads: END\n");
	431	}
	432
	433	void
	434	lalr (void)
	435	{
	436	initialize_LA ();
	437	set_goto_map ();
	438	initialize_F ();
	439	build_relations ();
	440	compute_FOLLOWS ();
	441	compute_lookaheads ();
	442
	443	if (trace_flag & trace_sets)
	444	lookaheads_print (stderr);
	445	}
	446
	447
	448	void
	449	lalr_free (void)
	450	{
	451	state_number_t s;
	452	for (s = 0; s < nstates; ++s)
	453	states[s]->reductions->lookaheads = NULL;
	454	bitsetv_free (LA);
	455	}