2007-02-07 Paolo Bonzini <bonzini@gnu.org>

[bison.git] / src / lalr.c

diff --git a/src/lalr.c b/src/lalr.c
index af2ea10012d48519898a6df2865a8260b1d5d263..f2bfa96738f2b4e5b1dcce61486bc4381c779064 100644 (file)
--- a/src/lalr.c
+++ b/src/lalr.c
@@ -1,5 +1,7 @@
-/* Compute look-ahead criteria for bison,
-   Copyright (C) 1984, 1986, 1989, 2000 Free Software Foundation, Inc.
+/* Compute lookahead criteria for Bison.
+
+   Copyright (C) 1984, 1986, 1989, 2000, 2001, 2002, 2003, 2004, 2005,
+   2006 Free Software Foundation, Inc.

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


@@ -15,629 +17,284 @@
 
    You should have received a copy of the GNU General Public License
    along with Bison; see the file COPYING.  If not, write to
 
    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.  */
+   the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+   Boston, MA 02110-1301, USA.  */

 
 
 /* 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 "alloc.h"
-#include "gram.h"

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

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

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

-#include "derives.h"
-
-int tokensetsize;
-short *lookaheads;
-short *LAruleno;
-unsigned *LA;
-short *accessing_symbol;
-char *consistent;
-core **state_table;
-shifts **shift_table;
-reductions **reduction_table;
-short *goto_map;
-short *from_state;
-short *to_state;
-
-extern void berror PARAMS ((const char *));
-
-static int infinity;
-static int maxrhs;
-static int ngotos;
-static unsigned *F;
-static short **includes;
-static shorts **lookback;
-static short **R;
-static short *INDEX;
-static short *VERTICES;
-static int top;
-
-
-static void
-traverse (int i)
-{
-  unsigned *fp1;
-  unsigned *fp2;
-  unsigned *fp3;
-  int j;
-  short *rp;
-
-  int height;
-  unsigned *base;
-
-  VERTICES[++top] = i;
-  INDEX[i] = height = top;
-
-  base = F + i * tokensetsize;
-  fp3 = base + tokensetsize;
-
-  rp = R[i];
-  if (rp)
-    {
-      while ((j = *rp++) >= 0)
-       {
-         if (INDEX[j] == 0)
-           traverse (j);
-
-         if (INDEX[i] > INDEX[j])
-           INDEX[i] = INDEX[j];
-
-         fp1 = base;
-         fp2 = F + j * tokensetsize;
-
-         while (fp1 < fp3)
-           *fp1++ |= *fp2++;
-       }
-    }
-
-  if (INDEX[i] == height)
-    {
-      for (;;)
-       {
-         j = VERTICES[top--];
-         INDEX[j] = infinity;
-
-         if (i == j)
-           break;
-
-         fp1 = base;
-         fp2 = F + j * tokensetsize;
-
-         while (fp1 < fp3)
-           *fp2++ = *fp1++;
-       }
-    }
-}
-
-
-static void
-digraph (short **relation)
-{
-  int i;
-
-  infinity = ngotos + 2;
-  INDEX = NEW2 (ngotos + 1, short);
-  VERTICES = NEW2 (ngotos + 1, short);
-  top = 0;
-
-  R = relation;
-
-  for (i = 0; i < ngotos; i++)
-    INDEX[i] = 0;
-
-  for (i = 0; i < ngotos; i++)
-    {
-      if (INDEX[i] == 0 && R[i])
-       traverse (i);
-    }
-
-  FREE (INDEX);
-  FREE (VERTICES);
-}
-
-static void
-set_state_table (void)
-{
-  core *sp;
-
-  state_table = NEW2 (nstates, core *);
-
-  for (sp = first_state; sp; sp = sp->next)
-    state_table[sp->number] = sp;
-}
-
-
-static void
-set_accessing_symbol (void)
-{
-  core *sp;
+#include "reader.h"
+#include "relation.h"
+#include "symtab.h"

 
 

-  accessing_symbol = NEW2 (nstates, short);
+goto_number *goto_map;
+static goto_number ngotos;
+state_number *from_state;
+state_number *to_state;

 
 

-  for (sp = first_state; sp; sp = sp->next)
-    accessing_symbol[sp->number] = sp->accessing_symbol;
-}
-
-
-static void
-set_shift_table (void)
-{
-  shifts *sp;
-
-  shift_table = NEW2 (nstates, shifts *);
-
-  for (sp = first_shift; sp; sp = sp->next)
-    shift_table[sp->number] = sp;
-}
-
-
-static void
-set_reduction_table (void)
-{
-  reductions *rp;
-
-  reduction_table = NEW2 (nstates, reductions *);
-
-  for (rp = first_reduction; rp; rp = rp->next)
-    reduction_table[rp->number] = rp;
-}
-
-
-static void
-set_maxrhs (void)
-{
-  short *itemp;
-  int length;
-  int max;
-
-  length = 0;
-  max = 0;
-  for (itemp = ritem; *itemp; itemp++)
-    {
-      if (*itemp > 0)
-       {
-         length++;
-       }
-      else
-       {
-         if (length > max)
-           max = length;
-         length = 0;
-       }
-    }
-
-  maxrhs = max;
-}
-
-
-static void
-initialize_LA (void)
+/* Linked list of goto numbers.  */
+typedef struct goto_list

 {
 {

-  int i;
-  int j;
-  int count;
-  reductions *rp;
-  shifts *sp;
-  short *np;
+  struct goto_list *next;
+  goto_number value;
+} goto_list;

 
 

-  consistent = NEW2 (nstates, char);
-  lookaheads = NEW2 (nstates + 1, short);

 
 

-  count = 0;
-  for (i = 0; i < nstates; i++)
-    {
-      int k;
+/* 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.  */

 
 

-      lookaheads[i] = count;
+static bitsetv LA = NULL;
+size_t nLA;

 
 

-      rp = reduction_table[i];
-      sp = shift_table[i];
-      if (rp && (rp->nreds > 1
-                || (sp && !ISVAR (accessing_symbol[sp->shifts[0]]))))
-       count += rp->nreds;
-      else
-       consistent[i] = 1;

 
 

-      if (sp)
-       for (k = 0; k < sp->nshifts; k++)
-         {
-           if (accessing_symbol[sp->shifts[k]] == error_token_number)
-             {
-               consistent[i] = 0;
-               break;
-             }
-         }
-    }
+/* And for the famous F variable, which name is so descriptive that a
+   comment is hardly needed.  <grin>.  */
+static bitsetv F = NULL;

 
 

-  lookaheads[nstates] = count;
+static goto_number **includes;
+static goto_list **lookback;

 
 

-  if (count == 0)
-    {
-      LA = NEW2 (1 * tokensetsize, unsigned);
-      LAruleno = NEW2 (1, short);
-      lookback = NEW2 (1, shorts *);
-    }
-  else
-    {
-      LA = NEW2 (count * tokensetsize, unsigned);
-      LAruleno = NEW2 (count, short);
-      lookback = NEW2 (count, shorts *);
-    }

 
 

-  np = LAruleno;
-  for (i = 0; i < nstates; i++)
-    {
-      if (!consistent[i])
-       {
-         if ((rp = reduction_table[i]))
-           for (j = 0; j < rp->nreds; j++)
-             *np++ = rp->rules[j];
-       }
-    }
-}

 
 
 static void
 set_goto_map (void)
 {
 
 
 static 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 = NEW2 (nvars + 1, short) - ntokens;
-  temp_map = NEW2 (nvars + 1, short) - 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 = accessing_symbol[sp->shifts[i]];
-
-         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 = NEW2 (ngotos, short);
-  to_state = NEW2 (ngotos, short);
+  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 = accessing_symbol[state2];
-
-         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;

        }
     }
 
        }
     }
 

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

 }
 
 
 
 }
 
 
 

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

 
 

-static int
-map_goto (int state, int symbol)
+static 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;
     }

-
-  berror ("map_goto");
-/* NOTREACHED */
-  return 0;

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

-  int i;
-  int j;
-  int k;
-  shifts *sp;
-  short *edge;
-  unsigned *rowp;
-  short *rp;
-  short **reads;
-  int nedges;
-  int stateno;
-  int symbol;
-  int nwords;
-
-  nwords = ngotos * tokensetsize;
-  F = NEW2 (nwords, unsigned);
-
-  reads = NEW2 (ngotos, short *);
-  edge = NEW2 (ngotos + 1, short);
-  nedges = 0;
-
-  rowp = F;
-  for (i = 0; i < ngotos; i++)
-    {
-      stateno = to_state[i];
-      sp = shift_table[stateno];
-
-      if (sp)
-       {
-         k = sp->nshifts;
+  goto_number **reads = xnmalloc (ngotos, sizeof *reads);
+  goto_number *edge = xnmalloc (ngotos + 1, sizeof *edge);
+  goto_number nedges = 0;

 
 

-         for (j = 0; j < k; j++)
-           {
-             symbol = accessing_symbol[sp->shifts[j]];
-             if (ISVAR (symbol))
-               break;
-             SETBIT (rowp, symbol);
-           }
+  goto_number i;

 
 

-         for (; j < k; j++)
-           {
-             symbol = accessing_symbol[sp->shifts[j]];
-             if (nullable[symbol])
-               edge[nedges++] = map_goto (stateno, symbol);
-           }
+  F = bitsetv_create (ngotos, ntokens, BITSET_FIXED);

 
 

-         if (nedges)
-           {
-             reads[i] = rp = NEW2 (nedges + 1, short);
+  for (i = 0; i < ngotos; i++)
+    {
+      state_number stateno = to_state[i];
+      transitions *sp = states[stateno]->transitions;

 
 

-             for (j = 0; j < nedges; j++)
-               rp[j] = edge[j];
+      int j;
+      FOR_EACH_SHIFT (sp, j)
+       bitset_set (F[i], TRANSITION_SYMBOL (sp, j));

 
 

-             rp[nedges] = -1;
-             nedges = 0;
-           }
+      for (; j < sp->num; j++)
+       {
+         symbol_number sym = TRANSITION_SYMBOL (sp, j);
+         if (nullable[sym - ntokens])
+           edge[nedges++] = map_goto (stateno, sym);

        }
 
        }
 

-      rowp += tokensetsize;
+      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, &F);

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

-    {
-      if (reads[i])
-       FREE (reads[i]);
-    }
+    free (reads[i]);

 
 

-  FREE (reads);
-  FREE (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 = lookaheads[stateno];
-  k = lookaheads[stateno + 1];
-  found = 0;
-  while (!found && i < k)
-    {
-      if (LAruleno[i] == ruleno)
-       found = 1;
-      else
-       i++;
-    }
-
-  assert (found);
-
-  sp = NEW (shorts);
-  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;

 }
 
 
 }
 
 

-static short **
-transpose (short **R_arg, int n)
-{
-  short **new_R;
-  short **temp_R;
-  short *nedges;
-  short *sp;
-  int i;
-  int k;
-
-  nedges = NEW2 (n, short);
-
-  for (i = 0; i < n; i++)
-    {
-      sp = R_arg[i];
-      if (sp)
-       {
-         while (*sp >= 0)
-           nedges[*sp++]++;
-       }
-    }
-
-  new_R = NEW2 (n, short *);
-  temp_R = NEW2 (n, short *);
-
-  for (i = 0; i < n; i++)
-    {
-      k = nedges[i];
-      if (k > 0)
-       {
-         sp = NEW2 (k + 1, short);
-         new_R[i] = sp;
-         temp_R[i] = sp;
-         sp[k] = -1;
-       }
-    }
-
-  FREE (nedges);
-
-  for (i = 0; i < n; i++)
-    {
-      sp = R_arg[i];
-      if (sp)
-       {
-         while (*sp >= 0)
-           *temp_R[*sp++]++ = i;
-       }
-    }
-
-  FREE (temp_R);
-
-  return new_R;
-}
-

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

-  int i;
-  int j;
-  int k;
-  short *rulep;
-  short *rp;
-  shifts *sp;
-  int length;
-  int nedges;
-  int done;
-  int state1;
-  int stateno;
-  int symbol1;
-  int symbol2;
-  short *shortp;
-  short *edge;
-  short *states;
-  short **new_includes;
-
-  includes = NEW2 (ngotos, short *);
-  edge = NEW2 (ngotos + 1, short);
-  states = NEW2 (maxrhs + 1, short);
+  goto_number *edge = xnmalloc (ngotos + 1, sizeof *edge);
+  state_number *states1 = xnmalloc (ritem_longest_rhs () + 1, sizeof *states1);
+  goto_number i;
+
+  includes = xnmalloc (ngotos, sizeof *includes);

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

-      nedges = 0;
-      state1 = from_state[i];
-      symbol1 = accessing_symbol[to_state[i]];
+      int nedges = 0;
+      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++)

        {
        {

-         length = 1;
-         states[0] = state1;
-         stateno = state1;
+         bool done;
+         int length = 1;
+         item_number const *rp;
+         state *s = states[from_state[i]];
+         states1[0] = s->number;

 
 

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

            {
            {

-             symbol2 = *rp;
-             sp = shift_table[stateno];
-             k = sp->nshifts;
-
-             for (j = 0; j < k; j++)
-               {
-                 stateno = sp->shifts[j];
-                 if (accessing_symbol[stateno] == symbol2)
-                   break;
-               }
-
-             states[length++] = stateno;
+             s = transitions_to (s->transitions,
+                                 item_number_as_symbol_number (*rp));
+             states1[length++] = s->number;

            }
 
            }
 

-         if (!consistent[stateno])
-           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 an item number, and there is a
+                sentinel 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

        {
        {

-         includes[i] = shortp = NEW2 (nedges + 1, short);
+         int j;
+         includes[i] = xnmalloc (nedges + 1, sizeof includes[i][0]);

          for (j = 0; j < nedges; j++)
          for (j = 0; j < nedges; j++)

-           shortp[j] = edge[j];
-         shortp[nedges] = -1;
+           includes[i][j] = edge[j];
+         includes[i][nedges] = END_NODE;

        }
     }
 
        }
     }
 

-  new_includes = transpose (includes, ngotos);
-
-  for (i = 0; i < ngotos; i++)
-    if (includes[i])
-      FREE (includes[i]);
-
-  FREE (includes);
+  free (edge);
+  free (states1);

 
 

-  includes = new_includes;
-
-  FREE (edge);
-  FREE (states);
+  relation_transpose (&includes, ngotos);

 }
 
 
 }
 
 


@@ -645,77 +302,162 @@ build_relations (void)
 static void
 compute_FOLLOWS (void)
 {
 static void
 compute_FOLLOWS (void)
 {

-  int i;
+  goto_number i;

 
 

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

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

-    {
-      if (includes[i])
-       FREE (includes[i]);
-    }
+    free (includes[i]);

 
 

-  FREE (includes);
+  free (includes);

 }
 
 
 static void
 }
 
 
 static void

-compute_lookaheads (void)
+compute_lookahead_tokens (void)

 {
 {

-  int i;
-  int n;
-  unsigned *fp1;
-  unsigned *fp2;
-  unsigned *fp3;
-  shorts *sp;
-  unsigned *rowp;
-  shorts *sptmp;               /* JF */
-
-  rowp = LA;
-  n = lookaheads[nstates];
-  for (i = 0; i < n; i++)
-    {
-      fp3 = rowp + tokensetsize;
-      for (sp = lookback[i]; sp; sp = sp->next)
-       {
-         fp1 = rowp;
-         fp2 = F + tokensetsize * sp->value;
-         while (fp1 < fp3)
-           *fp1++ |= *fp2++;
-       }
+  size_t i;
+  goto_list *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, lookback[i]);
+
+  free (lookback);
+  bitsetv_free (F);
+}
+
+
+/*----------------------------------------------------.
+| Count the number of lookahead tokens required for S |
+| (N_LOOKAHEAD_TOKENS member).                        |
+`----------------------------------------------------*/
+
+static int
+state_lookahead_tokens_count (state *s)
+{
+  int k;
+  int n_lookahead_tokens = 0;
+  reductions *rp = s->reductions;
+  transitions *sp = s->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)))
+    n_lookahead_tokens += rp->num;
+  else
+    s->consistent = 1;
+
+  for (k = 0; k < sp->num; k++)
+    if (!TRANSITION_IS_DISABLED (sp, k) && TRANSITION_IS_ERROR (sp, k))
+      {
+       s->consistent = 0;
+       break;
+      }
+
+  return n_lookahead_tokens;
+}

 
 

-      rowp = fp3;
-    }

 
 

-  for (i = 0; i < n; i++)
+/*----------------------------------------------------.
+| Compute LA, NLA, and the lookahead_tokens members.  |
+`----------------------------------------------------*/
+
+static void
+initialize_LA (void)
+{
+  state_number i;
+  bitsetv pLA;
+
+  /* Compute the total number of reductions requiring a lookahead.  */
+  nLA = 0;
+  for (i = 0; i < nstates; i++)
+    nLA += state_lookahead_tokens_count (states[i]);
+  /* Avoid having to special case 0.  */
+  if (!nLA)
+    nLA = 1;
+
+  pLA = LA = bitsetv_create (nLA, ntokens, BITSET_FIXED);
+  lookback = xcalloc (nLA, sizeof *lookback);
+
+  /* Initialize the members LOOKAHEAD_TOKENS for each state whose reductions
+     require lookahead tokens.  */
+  for (i = 0; i < nstates; i++)

     {
     {

-      /* JF removed ref to freed storage */
-      for (sp = lookback[i]; sp; sp = sptmp)
+      int count = state_lookahead_tokens_count (states[i]);
+      if (count)

        {
        {

-         sptmp = sp->next;
-         FREE (sp);
+         states[i]->reductions->lookahead_tokens = pLA;
+         pLA += count;

        }
     }
        }
     }

-
-  FREE (lookback);
-  FREE (F);

 }
 
 
 }
 
 

+/*---------------------------------------------.
+| 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)
 {
 void
 lalr (void)
 {

-  tokensetsize = WORDSIZE (ntokens);
-
-  set_state_table ();
-  set_accessing_symbol ();
-  set_shift_table ();
-  set_reduction_table ();
-  set_maxrhs ();

   initialize_LA ();
   set_goto_map ();
   initialize_F ();
   build_relations ();
   compute_FOLLOWS ();
   initialize_LA ();
   set_goto_map ();
   initialize_F ();
   build_relations ();
   compute_FOLLOWS ();

-  compute_lookaheads ();
+  compute_lookahead_tokens ();
+
+  if (trace_flag & trace_sets)
+    lookahead_tokens_print (stderr);
+}
+
+
+void
+lalr_free (void)
+{
+  state_number s;
+  for (s = 0; s < nstates; ++s)
+    states[s]->reductions->lookahead_tokens = NULL;
+  bitsetv_free (LA);

 }
 }