* src/lalr.c (state_lookahead_tokens_count): Correct comment.

[bison.git] / src / lalr.c

diff --git a/src/lalr.c b/src/lalr.c
index 674a121a86ea482fdcf65906e22bbe44fb7f35e0..fbd2800f0529905c30cd990bf30480c1e1fb75ed 100644 (file)
--- a/src/lalr.c
+++ b/src/lalr.c
@@ -1,539 +1,291 @@
-/* Compute look-ahead criteria for bison,
-   Copyright 1984, 1986, 1989, 2000, 2001  Free Software Foundation, Inc.
+/* Compute lookahead criteria for Bison.
+
+   Copyright (C) 1984, 1986, 1989, 2000, 2001, 2002, 2003, 2004, 2005,
+   2006, 2007, 2008, 2009 Free Software Foundation, Inc.

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

-   Bison is free software; you can redistribute it and/or modify
+   This program is free software: you can redistribute it and/or modify

    it under the terms of the GNU General Public License as published by
    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.
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.

 
 

-   Bison is distributed in the hope that it will be useful,
+   This program 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
    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.  */
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

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

+#include <config.h>

 #include "system.h"
 #include "system.h"

-#include "types.h"
+
+#include <bitset.h>
+#include <bitsetv.h>
+#include <quotearg.h>
+

 #include "LR0.h"
 #include "LR0.h"

-#include "gram.h"

 #include "complain.h"
 #include "complain.h"

+#include "derives.h"
+#include "getargs.h"
+#include "gram.h"

 #include "lalr.h"
 #include "lalr.h"

+#include "muscle-tab.h"

 #include "nullable.h"
 #include "nullable.h"

-#include "derives.h"
-
-/* All the decorated states, indexed by the state number.  Warning:
-   there is a state_TABLE in LR0.c, but it is different and static.
-   */
-state_t *state_table = NULL;
-
-int tokensetsize;
-short *LAruleno;
-unsigned *LA;
-
-short *goto_map;
-short *from_state;
-short *to_state;
-
-extern void berror PARAMS ((const char *));
-
-static int infinity;
-static int ngotos;
-
-/* And for the famous F variable, which name is so descriptive that a
-   comment is hardly needed.  <grin>.  */
-static unsigned *F = NULL;
-#define F(Rule)  (F + (Rule) * tokensetsize)
-
-static short **includes;
-static shorts **lookback;
-static short **R;
-static short *INDEX;
-static short *VERTICES;
-static int top;
-
-
-static void
-traverse (int i)
-{
-  int j;
-  size_t k;
-  int height;
-  size_t size = F (i + 1) - F(i);
-
-  VERTICES[++top] = i;
-  INDEX[i] = height = top;
-
-  if (R[i])
-    for (j = 0; R[i][j] >= 0; ++j)
-      {
-       if (INDEX[R[i][j]] == 0)
-         traverse (R[i][j]);
-
-       if (INDEX[i] > INDEX[R[i][j]])
-         INDEX[i] = INDEX[R[i][j]];
-
-       for (k = 0; k < size; ++k)
-         F (i)[k] |= F (R[i][j])[k];
-      }
-
-  if (INDEX[i] == height)
-    for (;;)
-      {
-       j = VERTICES[top--];
-       INDEX[j] = infinity;
-
-       if (i == j)
-         break;
-
-       for (k = 0; k < size; ++k)
-         F (i)[k] = F (j)[k];
-      }
-}
-
-
-static void
-digraph (short **relation)
+#include "reader.h"
+#include "relation.h"
+#include "symtab.h"
+
+goto_number *goto_map;
+goto_number ngotos;
+state_number *from_state;
+state_number *to_state;
+bitsetv goto_follows = NULL;
+
+/* Linked list of goto numbers.  */
+typedef struct goto_list

 {
 {

-  int i;
+  struct goto_list *next;
+  goto_number value;
+} goto_list;

 
 

-  infinity = ngotos + 2;
-  INDEX = XCALLOC (short, ngotos + 1);
-  VERTICES = XCALLOC (short, ngotos + 1);
-  top = 0;

 
 

-  R = relation;
+/* LA is an NLA 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.  */

 
 

-  for (i = 0; i < ngotos; i++)
-    INDEX[i] = 0;
+static bitsetv LA = NULL;
+size_t nLA;

 
 

-  for (i = 0; i < ngotos; i++)
-    if (INDEX[i] == 0 && R[i])
-      traverse (i);
-
-  XFREE (INDEX);
-  XFREE (VERTICES);
-}

 
 

+static goto_number **includes;
+static goto_list **lookback;

 
 

-/*--------------------.
-| Build STATE_TABLE.  |
-`--------------------*/

 
 

-static void
-set_state_table (void)
-{
-  /* NSTATES + 1 because lookahead for the pseudo state number NSTATES
-     might be used (see conflicts.c).  It is too opaque for me to
-     provide a probably less hacky implementation. --akim */
-  state_table = XCALLOC (state_t, nstates + 1);

 
 

-  {
-    core *sp;
-    for (sp = first_state; sp; sp = sp->next)
-      {
-       state_table[sp->number].state = sp;
-       state_table[sp->number].accessing_symbol = sp->accessing_symbol;
-      }
-  }
-
-  {
-    shifts *sp;
-    for (sp = first_shift; sp; sp = sp->next)
-      state_table[sp->number].shift_table = sp;
-  }

 
 

-  {
-    reductions *rp;
-    for (rp = first_reduction; rp; rp = rp->next)
-      state_table[rp->number].reduction_table = rp;
-  }
-
-  /* Initializing the lookaheads members.  Please note that it must be
-     performed after having set some of the other members which are
-     used below.  Change with extreme caution.  */
-  {
-    int i;
-    int count = 0;
-    for (i = 0; i < nstates; i++)
-      {
-       int k;
-       reductions *rp = state_table[i].reduction_table;
-       shifts *sp = state_table[i].shift_table;
-
-       state_table[i].lookaheads = count;
-
-       if (rp
-           && (rp->nreds > 1
-               || (sp && !ISVAR (state_table[sp->shifts[0]].accessing_symbol))))
-         count += rp->nreds;
-       else
-         state_table[i].consistent = 1;
-
-       if (sp)
-         for (k = 0; k < sp->nshifts; k++)
-           if (state_table[sp->shifts[k]].accessing_symbol
-               == error_token_number)
-             {
-               state_table[i].consistent = 0;
-               break;
-             }
-      }
-     state_table[nstates].lookaheads = count;
-  }
-}
-
-
-static void
-initialize_LA (void)
-{
-  int i;
-  int j;
-  short *np;
-  reductions *rp;
-
-  size_t nLA = state_table[nstates].lookaheads;
-  if (!nLA)
-    nLA = 1;
-
-  LA = XCALLOC (unsigned, nLA * tokensetsize);
-  LAruleno = XCALLOC (short, nLA);
-  lookback = XCALLOC (shorts *, nLA);
-
-  np = LAruleno;
-  for (i = 0; i < nstates; i++)
-    if (!state_table[i].consistent)
-      if ((rp = state_table[i].reduction_table))
-       for (j = 0; j < rp->nreds; j++)
-         *np++ = rp->rules[j];
-}
-
-
-static void
+void

 set_goto_map (void)
 {
 set_goto_map (void)
 {

-  shifts *sp;
-  int i;
-  int symbol;
-  int k;
-  short *temp_map;
-  int state2;
-  int state1;
+  state_number s;
+  goto_number *temp_map;

 
 

-  goto_map = XCALLOC (short, nvars + 1) - ntokens;
-  temp_map = XCALLOC (short, nvars + 1) - ntokens;
+  goto_map = xcalloc (nvars + 1, sizeof *goto_map);
+  temp_map = xnmalloc (nvars + 1, sizeof *temp_map);

 
   ngotos = 0;
 
   ngotos = 0;

-  for (sp = first_shift; sp; sp = sp->next)
+  for (s = 0; s < nstates; ++s)

     {
     {

-      for (i = sp->nshifts - 1; i >= 0; i--)
+      transitions *sp = states[s]->transitions;
+      int i;
+      for (i = sp->num - 1; i >= 0 && TRANSITION_IS_GOTO (sp, i); --i)

        {
        {

-         symbol = state_table[sp->shifts[i]].accessing_symbol;
-
-         if (ISTOKEN (symbol))
-           break;
+         ngotos++;

 
 

-         if (ngotos == MAXSHORT)
-           fatal (_("too many gotos (max %d)"), MAXSHORT);
+         /* Abort if (ngotos + 1) would overflow.  */
+         aver (ngotos != GOTO_NUMBER_MAXIMUM);

 
 

-         ngotos++;
-         goto_map[symbol]++;
+         goto_map[TRANSITION_SYMBOL (sp, i) - ntokens]++;

        }
     }
 
        }
     }
 

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

 
 

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

 
 

-  goto_map[nsyms] = ngotos;
-  temp_map[nsyms] = ngotos;
+    goto_map[nsyms - ntokens] = ngotos;
+    temp_map[nsyms - ntokens] = ngotos;
+  }

 
 

-  from_state = XCALLOC (short, ngotos);
-  to_state = XCALLOC (short, ngotos);
+  from_state = xcalloc (ngotos, sizeof *from_state);
+  to_state = xcalloc (ngotos, sizeof *to_state);

 
 

-  for (sp = first_shift; sp; sp = sp->next)
+  for (s = 0; s < nstates; ++s)

     {
     {

-      state1 = sp->number;
-      for (i = sp->nshifts - 1; i >= 0; i--)
+      transitions *sp = states[s]->transitions;
+      int i;
+      for (i = sp->num - 1; i >= 0 && TRANSITION_IS_GOTO (sp, i); --i)

        {
        {

-         state2 = sp->shifts[i];
-         symbol = state_table[state2].accessing_symbol;
-
-         if (ISTOKEN (symbol))
-           break;
-
-         k = temp_map[symbol]++;
-         from_state[k] = state1;
-         to_state[k] = state2;
+         goto_number k = temp_map[TRANSITION_SYMBOL (sp, i) - ntokens]++;
+         from_state[k] = s;
+         to_state[k] = sp->states[i]->number;

        }
     }
 
        }
     }
 

-  XFREE (temp_map + ntokens);
+  free (temp_map);

 }
 
 
 }
 
 

-
-/*----------------------------------------------------------.
-| Map a state/symbol pair into its numeric representation.  |
-`----------------------------------------------------------*/
-
-static int
-map_goto (int state, int symbol)
+goto_number
+map_goto (state_number s0, symbol_number sym)

 {
 {

-  int high;
-  int low;
-  int middle;
-  int s;
+  goto_number high;
+  goto_number low;
+  goto_number middle;
+  state_number s;

 
 

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

 
 

-  while (low <= high)
+  for (;;)

     {
     {

+      aver (low <= high);

       middle = (low + high) / 2;
       s = from_state[middle];
       middle = (low + high) / 2;
       s = from_state[middle];

-      if (s == state)
+      if (s == s0)

        return middle;
        return middle;

-      else if (s < state)
+      else if (s < s0)

        low = middle + 1;
       else
        high = middle - 1;
     }
        low = middle + 1;
       else
        high = middle - 1;
     }

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

 }
 
 
 static void
 initialize_F (void)
 {
 }
 
 
 static void
 initialize_F (void)
 {

-  short **reads = XCALLOC (short *, ngotos);
-  short *edge = XCALLOC (short, ngotos + 1);
-  int nedges = 0;
+  goto_number **reads = xnmalloc (ngotos, sizeof *reads);
+  goto_number *edge = xnmalloc (ngotos + 1, sizeof *edge);
+  goto_number nedges = 0;

 
 

-  int i;
+  goto_number i;

 
 

-  F = XCALLOC (unsigned, ngotos * tokensetsize);
+  goto_follows = bitsetv_create (ngotos, ntokens, BITSET_FIXED);

 
   for (i = 0; i < ngotos; i++)
     {
 
   for (i = 0; i < ngotos; i++)
     {

-      int stateno = to_state[i];
-      shifts *sp = state_table[stateno].shift_table;
+      state_number stateno = to_state[i];
+      transitions *sp = states[stateno]->transitions;

 
 

-      if (sp)
-       {
-         int j;
-         for (j = 0; j < sp->nshifts; j++)
-           {
-             int symbol = state_table[sp->shifts[j]].accessing_symbol;
-             if (ISVAR (symbol))
-               break;
-             SETBIT (F + i * tokensetsize, symbol);
-           }
+      int j;
+      FOR_EACH_SHIFT (sp, j)
+       bitset_set (goto_follows[i], TRANSITION_SYMBOL (sp, j));

 
 

-         for (; j < sp->nshifts; j++)
-           {
-             int symbol = state_table[sp->shifts[j]].accessing_symbol;
-             if (nullable[symbol])
-               edge[nedges++] = map_goto (stateno, symbol);
-           }
+      for (; j < sp->num; j++)
+       {
+         symbol_number sym = TRANSITION_SYMBOL (sp, j);
+         if (nullable[sym - ntokens])
+           edge[nedges++] = map_goto (stateno, sym);
+       }

 
 

-         if (nedges)
-           {
-             reads[i] = XCALLOC (short, nedges + 1);
-             shortcpy (reads[i], edge, nedges);
-             reads[i][nedges] = -1;
-             nedges = 0;
-           }
+      if (nedges == 0)
+       reads[i] = NULL;
+      else
+       {
+         reads[i] = xnmalloc (nedges + 1, sizeof reads[i][0]);
+         memcpy (reads[i], edge, nedges * sizeof edge[0]);
+         reads[i][nedges] = END_NODE;
+         nedges = 0;

        }
     }
 
        }
     }
 

-  digraph (reads);
+  relation_digraph (reads, ngotos, &goto_follows);

 
   for (i = 0; i < ngotos; i++)
 
   for (i = 0; i < ngotos; i++)

-    XFREE (reads[i]);
+    free (reads[i]);

 
 

-  XFREE (reads);
-  XFREE (edge);
+  free (reads);
+  free (edge);

 }
 
 
 static void
 }
 
 
 static void

-add_lookback_edge (int stateno, int ruleno, int gotono)
+add_lookback_edge (state *s, rule *r, goto_number gotono)

 {
 {

-  int i;
-  int k;
-  int found;
-  shorts *sp;
-
-  i = state_table[stateno].lookaheads;
-  k = state_table[stateno + 1].lookaheads;
-  found = 0;
-  while (!found && i < k)
-    {
-      if (LAruleno[i] == ruleno)
-       found = 1;
-      else
-       i++;
-    }
-
-  assert (found);
-
-  sp = XCALLOC (shorts, 1);
-  sp->next = lookback[i];
+  int ri = state_reduction_find (s, r);
+  goto_list *sp = xmalloc (sizeof *sp);
+  sp->next = lookback[(s->reductions->lookahead_tokens - LA) + ri];

   sp->value = gotono;
   sp->value = gotono;

-  lookback[i] = sp;
+  lookback[(s->reductions->lookahead_tokens - LA) + ri] = sp;

 }
 
 
 }
 
 

-/*-------------------------------------------------------------------.
-| Return the transpose of R_ARG, of size N.  Destroy R_ARG, as it is |
-| replaced with the result.                                          |
-`-------------------------------------------------------------------*/
-
-static short **
-transpose (short **R_arg, int n)
-{
-  short **new_R;
-  short **temp_R;
-  short *nedges;
-  int i;
-
-  nedges = XCALLOC (short, n);
-
-  for (i = 0; i < n; i++)
-    {
-      short *sp = R_arg[i];
-      if (sp)
-       {
-         while (*sp >= 0)
-           nedges[*sp++]++;
-       }
-    }
-
-  new_R = XCALLOC (short *, n);
-  temp_R = XCALLOC (short *, n);
-
-  for (i = 0; i < n; i++)
-    if (nedges[i] > 0)
-      {
-       short *sp = XCALLOC (short, nedges[i] + 1);
-       new_R[i] = sp;
-       temp_R[i] = sp;
-       sp[nedges[i]] = -1;
-      }
-
-  XFREE (nedges);
-
-  for (i = 0; i < n; i++)
-    {
-      short *sp = R_arg[i];
-      if (sp)
-       while (*sp >= 0)
-         *temp_R[*sp++]++ = i;
-    }
-
-  XFREE (temp_R);
-
-  /* Free the input: it is replaced with the result. */
-  for (i = 0; i < n; i++)
-    XFREE (R_arg[i]);
-  XFREE (R_arg);
-
-  return new_R;
-}
-

 
 static void
 build_relations (void)
 {
 
 static void
 build_relations (void)
 {

-  short *edge = XCALLOC (short, ngotos + 1);
-  short *states = XCALLOC (short, ritem_longest_rhs () + 1);
-  int i;
+  goto_number *edge = xnmalloc (ngotos + 1, sizeof *edge);
+  state_number *states1 = xnmalloc (ritem_longest_rhs () + 1, sizeof *states1);
+  goto_number i;

 
 

-  includes = XCALLOC (short *, ngotos);
+  includes = xnmalloc (ngotos, sizeof *includes);

 
   for (i = 0; i < ngotos; i++)
     {
       int nedges = 0;
 
   for (i = 0; i < ngotos; i++)
     {
       int nedges = 0;

-      int state1 = from_state[i];
-      int symbol1 = state_table[to_state[i]].accessing_symbol;
-      short *rulep;
+      symbol_number symbol1 = states[to_state[i]]->accessing_symbol;
+      rule **rulep;

 
 

-      for (rulep = derives[symbol1]; *rulep > 0; rulep++)
+      for (rulep = derives[symbol1 - ntokens]; *rulep; rulep++)

        {
        {

-         int done;
+         bool done;

          int length = 1;
          int length = 1;

-         int stateno = state1;
-         short *rp;
-         states[0] = state1;
+         item_number const *rp;
+         state *s = states[from_state[i]];
+         states1[0] = s->number;

 
 

-         for (rp = ritem + rule_table[*rulep].rhs; *rp > 0; rp++)
+         for (rp = (*rulep)->rhs; ! item_number_is_rule_number (*rp); rp++)

            {
            {

-             shifts *sp = state_table[stateno].shift_table;
-             int j;
-             for (j = 0; j < sp->nshifts; j++)
-               {
-                 stateno = sp->shifts[j];
-                 if (state_table[stateno].accessing_symbol == *rp)
-                   break;
-               }
-
-             states[length++] = stateno;
+             s = transitions_to (s->transitions,
+                                 item_number_as_symbol_number (*rp));
+             states1[length++] = s->number;

            }
 
            }
 

-         if (!state_table[stateno].consistent)
-           add_lookback_edge (stateno, *rulep, i);
+         if (!s->consistent)
+           add_lookback_edge (s, *rulep, i);

 
          length--;
 
          length--;

-         done = 0;
+         done = false;

          while (!done)
            {
          while (!done)
            {

-             done = 1;
+             done = true;
+             /* Each rhs ends in a rule number, and there is a
+                sentinel (ritem[-1]=0) before the first rhs, so it is safe to
+                decrement RP here.  */

              rp--;
              rp--;

-             /* JF added rp>=ritem &&   I hope to god its right! */
-             if (rp >= ritem && ISVAR (*rp))
+             if (ISVAR (*rp))

                {
                {

-                 stateno = states[--length];
-                 edge[nedges++] = map_goto (stateno, *rp);
-                 if (nullable[*rp])
-                   done = 0;
+                 /* Downcasting from item_number to symbol_number.  */
+                 edge[nedges++] = map_goto (states1[--length],
+                                            item_number_as_symbol_number (*rp));
+                 if (nullable[*rp - ntokens])
+                   done = false;

                }
            }
        }
 
                }
            }
        }
 

-      if (nedges)
+      if (nedges == 0)
+       includes[i] = NULL;
+      else

        {
          int j;
        {
          int j;

-         includes[i] = XCALLOC (short, nedges + 1);
+         includes[i] = xnmalloc (nedges + 1, sizeof includes[i][0]);

          for (j = 0; j < nedges; j++)
            includes[i][j] = edge[j];
          for (j = 0; j < nedges; j++)
            includes[i][j] = edge[j];

-         includes[i][nedges] = -1;
+         includes[i][nedges] = END_NODE;

        }
     }
 
        }
     }
 

-  XFREE (edge);
-  XFREE (states);
+  free (edge);
+  free (states1);

 
 

-  includes = transpose (includes, ngotos);
+  relation_transpose (&includes, ngotos);

 }
 
 
 }
 
 


@@ -541,51 +293,211 @@ build_relations (void)
 static void
 compute_FOLLOWS (void)
 {
 static void
 compute_FOLLOWS (void)
 {

-  int i;
+  goto_number i;

 
 

-  digraph (includes);
+  relation_digraph (includes, ngotos, &goto_follows);

 
   for (i = 0; i < ngotos; i++)
 
   for (i = 0; i < ngotos; i++)

-    XFREE (includes[i]);
+    free (includes[i]);

 
 

-  XFREE (includes);
+  free (includes);

 }
 
 
 static void
 }
 
 
 static void

-compute_lookaheads (void)
+compute_lookahead_tokens (void)

 {
 {

-  int i;
-  shorts *sp;
+  size_t i;
+  goto_list *sp;

 
 

-  for (i = 0; i < state_table[nstates].lookaheads; i++)
+  for (i = 0; i < nLA; i++)

     for (sp = lookback[i]; sp; sp = sp->next)
     for (sp = lookback[i]; sp; sp = sp->next)

-      {
-       int size = LA (i + 1) - LA (i);
-       int j;
-       for (j = 0; j < size; ++j)
-         LA (i)[j] |= F (sp->value)[j];
-      }
+      bitset_or (LA[i], LA[i], goto_follows[sp->value]);

 
   /* Free LOOKBACK. */
 
   /* Free LOOKBACK. */

-  for (i = 0; i < state_table[nstates].lookaheads; i++)
-    LIST_FREE (shorts, lookback[i]);
+  for (i = 0; i < nLA; i++)
+    LIST_FREE (goto_list, lookback[i]);

 
 

-  XFREE (lookback);
-  XFREE (F);
+  free (lookback);
+}
+
+
+/*----------------------------------------------------.
+| Count the number of lookahead tokens required for S |
+| (N_LOOKAHEAD_TOKENS member).                        |
+`----------------------------------------------------*/
+
+static int
+state_lookahead_tokens_count (state *s, bool default_reduction_only_for_accept)
+{
+  int n_lookahead_tokens = 0;
+  reductions *rp = s->reductions;
+  transitions *sp = s->transitions;
+
+  /* Transitions are only disabled during conflict resolution, and that
+     hasn't happened yet, so there should be no need to check that
+     transition 0 hasn't been disabled before checking if it is a shift.
+     However, this check was performed at one time, so we leave it as an
+     aver.  */
+  aver (sp->num == 0 || !TRANSITION_IS_DISABLED (sp, 0));
+
+  /* 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'.  However, do not treat a state with any reductions as
+     consistent unless it is the accepting state (because there is never
+     a lookahead token that makes sense there, and so no lookahead token
+     should be read) if the user has otherwise disabled default
+     reductions.  */
+  if (rp->num > 1
+      || (rp->num == 1 && sp->num && TRANSITION_IS_SHIFT (sp, 0))
+      || (rp->num == 1 && rp->rules[0]->number != 0
+          && default_reduction_only_for_accept))
+    n_lookahead_tokens += rp->num;
+  else
+    s->consistent = 1;
+
+  return n_lookahead_tokens;

 }
 
 
 }
 
 

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

 void
 void

-lalr (void)
+initialize_LA (void)

 {
 {

-  tokensetsize = WORDSIZE (ntokens);
+  state_number i;
+  bitsetv pLA;
+  bool default_reduction_only_for_accept;
+  {
+    char *default_reductions =
+      muscle_percent_define_get ("lr.default-reductions");
+    default_reduction_only_for_accept =
+      0 == strcmp (default_reductions, "accepting");
+    free (default_reductions);
+  }
+
+  /* Compute the total number of reductions requiring a lookahead.  */
+  nLA = 0;
+  for (i = 0; i < nstates; i++)
+    nLA +=
+      state_lookahead_tokens_count (states[i],
+                                    default_reduction_only_for_accept);
+  /* Avoid having to special case 0.  */
+  if (!nLA)
+    nLA = 1;

 
 

-  set_state_table ();
+  pLA = LA = bitsetv_create (nLA, ntokens, BITSET_FIXED);
+
+  /* Initialize the members LOOKAHEAD_TOKENS for each state whose reductions
+     require lookahead tokens.  */
+  for (i = 0; i < nstates; i++)
+    {
+      int count =
+        state_lookahead_tokens_count (states[i],
+                                      default_reduction_only_for_accept);
+      if (count)
+       {
+         states[i]->reductions->lookahead_tokens = pLA;
+         pLA += count;
+       }
+    }
+}
+
+
+/*---------------------------------------------.
+| Output the lookahead tokens for each state.  |
+`---------------------------------------------*/
+
+static void
+lookahead_tokens_print (FILE *out)
+{
+  state_number i;
+  int j, k;
+  fprintf (out, "Lookahead tokens: BEGIN\n");
+  for (i = 0; i < nstates; ++i)
+    {
+      reductions *reds = states[i]->reductions;
+      bitset_iterator iter;
+      int n_lookahead_tokens = 0;
+
+      if (reds->lookahead_tokens)
+       for (k = 0; k < reds->num; ++k)
+         if (reds->lookahead_tokens[k])
+           ++n_lookahead_tokens;
+
+      fprintf (out, "State %d: %d lookahead tokens\n",
+              i, n_lookahead_tokens);
+
+      if (reds->lookahead_tokens)
+       for (j = 0; j < reds->num; ++j)
+         BITSET_FOR_EACH (iter, reds->lookahead_tokens[j], k, 0)
+         {
+           fprintf (out, "   on %d (%s) -> rule %d\n",
+                    k, symbols[k]->tag,
+                    reds->rules[j]->number);
+         };
+    }
+  fprintf (out, "Lookahead tokens: END\n");
+}
+
+void
+lalr (void)
+{

   initialize_LA ();
   set_goto_map ();
   initialize_F ();
   initialize_LA ();
   set_goto_map ();
   initialize_F ();

+  lookback = xcalloc (nLA, sizeof *lookback);

   build_relations ();
   compute_FOLLOWS ();
   build_relations ();
   compute_FOLLOWS ();

-  compute_lookaheads ();
+  compute_lookahead_tokens ();
+
+  if (trace_flag & trace_sets)
+    lookahead_tokens_print (stderr);
+}
+
+
+void
+lalr_update_state_numbers (state_number old_to_new[], state_number nstates_old)
+{
+  goto_number ngotos_reachable = 0;
+  symbol_number nonterminal = 0;
+  aver (nsyms == nvars + ntokens);
+  {
+    goto_number i;
+    for (i = 0; i < ngotos; ++i)
+      {
+        while (i == goto_map[nonterminal])
+          goto_map[nonterminal++] = ngotos_reachable;
+        /* If old_to_new[from_state[i]] = nstates_old, remove this goto
+           entry.  */
+        if (old_to_new[from_state[i]] != nstates_old)
+          {
+            /* from_state[i] is not removed, so it and thus to_state[i] are
+               reachable, so to_state[i] != nstates_old.  */
+            aver (old_to_new[to_state[i]] != nstates_old);
+            from_state[ngotos_reachable] = old_to_new[from_state[i]];
+            to_state[ngotos_reachable] = old_to_new[to_state[i]];
+            ++ngotos_reachable;
+          }
+      }
+  }
+  while (nonterminal <= nvars)
+    {
+      aver (ngotos == goto_map[nonterminal]);
+      goto_map[nonterminal++] = ngotos_reachable;
+    }
+  ngotos = ngotos_reachable;
+}
+
+
+void
+lalr_free (void)
+{
+  state_number s;
+  for (s = 0; s < nstates; ++s)
+    states[s]->reductions->lookahead_tokens = NULL;
+  bitsetv_free (LA);

 }
 }