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