Do not let the scan-skel token buffer grow unboundedly in the usual case.

[bison.git] / src / lalr.c

diff --git a/src/lalr.c b/src/lalr.c
index 42cd05ef938f287ae97866fccd98c1c7a02eb29d..4e59d0ad4ac3f5571b1ab7a77b13b35aa7d1e763 100644 (file)
--- a/src/lalr.c
+++ b/src/lalr.c
@@ -1,5 +1,7 @@
-/* Compute look-ahead criteria for bison,
-   Copyright 1984, 1986, 1989, 2000, 2001  Free Software Foundation, Inc.
+/* 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.
 
 
    This file is part of Bison, the GNU Compiler Compiler.
 


@@ -24,313 +26,109 @@
    tokens they accept.  */
 
 #include "system.h"
    tokens they accept.  */
 
 #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 "nullable.h"
 #include "lalr.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 named 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)
-{
-  unsigned *fp1;
-  unsigned *fp2;
-  unsigned *fp3;
-  int j;
-  short *rp;
-
-  int height;
-  unsigned *base;
-
-  VERTICES[++top] = i;
-  INDEX[i] = height = top;
-
-  base = F (i);
-  fp3 = F (i + 1);
-
-  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);
+#include "reader.h"
+#include "relation.h"
+#include "symtab.h"

 
 

-         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);
+goto_number *goto_map = NULL;
+static goto_number ngotos = 0;
+state_number *from_state = NULL;
+state_number *to_state = NULL;

 
 

-         while (fp1 < fp3)
-           *fp2++ = *fp1++;
-       }
-    }
-}
-
-
-static void
-digraph (short **relation)
-{
-  int i;
-
-  infinity = ngotos + 2;
-  INDEX = XCALLOC (short, ngotos + 1);
-  VERTICES = XCALLOC (short, ngotos + 1);
-  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);
-
-  XFREE (INDEX);
-  XFREE (VERTICES);
-}
-
-
-/*--------------------.
-| Build STATE_TABLE.  |
-`--------------------*/
-
-static void
-set_state_table (void)
+/* Linked list of goto numbers.  */
+typedef struct goto_list

 {
 {

-  /* 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);
+  struct goto_list *next;
+  goto_number value;
+} goto_list;

 
 

-  {
-    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;
-  }
-}
-
-
-/* Return the size of the longest ride hand side of the rules. */
-static size_t
-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;
-       }
-    }
+/* 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.  */

 
 

-  return max;
-}
+static bitsetv LA = NULL;
+size_t nLA;

 
 
 
 

-static void
-initialize_LA (void)
-{
-  int i;
-  int j;
-  short *np;
-  reductions *rp;
+/* And for the famous F variable, which name is so descriptive that a
+   comment is hardly needed.  <grin>.  */
+static bitsetv F = NULL;

 
 

-  size_t nLA = state_table[nstates].lookaheads;
-  if (!nLA)
-    nLA = 1;
+static goto_number **includes;
+static goto_list **lookback;

 
 

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

 
   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;
-
-         if (ngotos == MAXSHORT)
-           fatal (_("too many gotos (max %d)"), MAXSHORT);
-
+         if (ngotos >= GOTO_NUMBER_MAXIMUM)
+           abort ();

          ngotos++;
          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];
-    }
+  {
+    int 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);
+  CALLOC (from_state, ngotos);
+  CALLOC (to_state, ngotos);

 
 

-  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;
+         int k = temp_map[TRANSITION_SYMBOL (sp, i) - ntokens]++;
+         from_state[k] = s;
+         to_state[k] = sp->states[i]->number;

        }
     }
 
        }
     }
 

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

 }
 
 
 }
 
 


@@ -340,98 +138,69 @@ set_goto_map (void)
 `----------------------------------------------------------*/
 
 static int
 `----------------------------------------------------------*/
 
 static int

-map_goto (int state, int symbol)
+map_goto (state_number s0, symbol_number sym)

 {
   int high;
   int low;
   int middle;
 {
   int high;
   int low;
   int middle;

-  int s;
+  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 (;;)

     {
     {

+      if (high < low)
+       abort ();

       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)
 {

-  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 = XCALLOC (unsigned, nwords);
-
-  reads = XCALLOC (short *, ngotos);
-  edge = XCALLOC (short, ngotos + 1);
-  nedges = 0;
-
-  rowp = F;
-  for (i = 0; i < ngotos; i++)
-    {
-      stateno = to_state[i];
-      sp = state_table[stateno].shift_table;
-
-      if (sp)
-       {
-         k = sp->nshifts;
+  goto_number **reads = CALLOC (reads, ngotos);
+  goto_number *edge = CALLOC (edge, ngotos + 1);
+  int nedges = 0;

 
 

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

 
 

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

 
 

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

     }
 
     }
 

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

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


@@ -442,143 +211,49 @@ initialize_F (void)
 
 
 static void
 
 
 static void

-add_lookback_edge (int stateno, int ruleno, int gotono)
+add_lookback_edge (state *s, rule *r, int 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 = MALLOC (sp, 1);
+  sp->next = lookback[(s->reductions->lookaheads - LA) + ri];

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

-  lookback[i] = sp;
+  lookback[(s->reductions->lookaheads - 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 = XCALLOC (short, n);
-
-  for (i = 0; i < n; i++)
-    {
-      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++)
-    {
-      k = nedges[i];
-      if (k > 0)
-       {
-         sp = XCALLOC (short, k + 1);
-         new_R[i] = sp;
-         temp_R[i] = sp;
-         sp[k] = -1;
-       }
-    }
-
-  XFREE (nedges);
-
-  for (i = 0; i < n; i++)
-    {
-      sp = R_arg[i];
-      if (sp)
-       {
-         while (*sp >= 0)
-           *temp_R[*sp++]++ = i;
-       }
-    }
-
-  XFREE (temp_R);
-
-  return new_R;
-}
-

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

+  goto_number *edge = CALLOC (edge, ngotos + 1);
+  state_number *states1 = CALLOC (states1, ritem_longest_rhs () + 1);

   int i;
   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 = XCALLOC (short *, ngotos);
-  edge = XCALLOC (short, ngotos + 1);
-  states = XCALLOC (short, maxrhs () + 1);
+
+  CALLOC (includes, ngotos);

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

-      nedges = 0;
-      state1 = from_state[i];
-      symbol1 = state_table[to_state[i]].accessing_symbol;
+      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;
+         int done;
+         int length = 1;
+         item_number *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; *rp >= 0; rp++)

            {
            {

-             symbol2 = *rp;
-             sp = state_table[stateno].shift_table;
-             k = sp->nshifts;
-
-             for (j = 0; j < k; j++)
-               {
-                 stateno = sp->shifts[j];
-                 if (state_table[stateno].accessing_symbol == symbol2)
-                   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--;
          done = 0;
 
          length--;
          done = 0;


@@ -589,9 +264,10 @@ build_relations (void)
              /* JF added rp>=ritem &&   I hope to god its right! */
              if (rp >= ritem && ISVAR (*rp))
                {
              /* JF added rp>=ritem &&   I hope to god its right! */
              if (rp >= ritem && ISVAR (*rp))
                {

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

                    done = 0;
                }
            }
                    done = 0;
                }
            }


@@ -599,25 +275,18 @@ build_relations (void)
 
       if (nedges)
        {
 
       if (nedges)
        {

-         includes[i] = shortp = XCALLOC (short, nedges + 1);
+         int j;
+         CALLOC (includes[i], nedges + 1);

          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] = -1;

        }
     }
 
        }
     }
 

-  new_includes = transpose (includes, ngotos);
-
-  for (i = 0; i < ngotos; i++)
-    if (includes[i])
-      XFREE (includes[i]);
-
-  XFREE (includes);
-
-  includes = new_includes;
-

   XFREE (edge);
   XFREE (edge);

-  XFREE (states);
+  XFREE (states1);
+
+  relation_transpose (&includes, ngotos);

 }
 
 
 }
 
 


@@ -627,7 +296,7 @@ compute_FOLLOWS (void)
 {
   int i;
 
 {
   int i;
 

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

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


@@ -639,37 +308,148 @@ compute_FOLLOWS (void)
 static void
 compute_lookaheads (void)
 {
 static void
 compute_lookaheads (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)

-      {
-       unsigned *fp1 = LA (i);
-       unsigned *fp2 = F (sp->value);
-       while (fp1 < LA (i + 1))
-         *fp1++ |= *fp2++;
-      }
+      bitset_or (LA[i], LA[i], F[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 (lookback);

-  XFREE (F);
+  bitsetv_free (F);
+}
+
+
+/*-----------------------------------------------------------.
+| Count the number of lookaheads required for S (NLOOKAHEADS |
+| member).                                                   |
+`-----------------------------------------------------------*/
+
+static int
+state_lookaheads_count (state *s)
+{
+  int k;
+  int nlookaheads = 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)))
+    nlookaheads += 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 nlookaheads;
+}
+
+
+/*----------------------------------------------.
+| Compute LA, NLA, and the lookaheads 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_lookaheads_count (states[i]);
+  /* Avoid having to special case 0.  */
+  if (!nLA)
+    nLA = 1;
+
+  pLA = LA = bitsetv_create (nLA, ntokens, BITSET_FIXED);
+  CALLOC (lookback, 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 i;
+  int j, k;
+  fprintf (out, "Lookaheads: BEGIN\n");
+  for (i = 0; i < nstates; ++i)
+    {
+      reductions *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)
 {
 void
 lalr (void)
 {

-  tokensetsize = WORDSIZE (ntokens);
-
-  set_state_table ();

   initialize_LA ();
   set_goto_map ();
   initialize_F ();
   build_relations ();
   compute_FOLLOWS ();
   compute_lookaheads ();
   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 s;
+  for (s = 0; s < nstates; ++s)
+    states[s]->reductions->lookaheads = NULL;
+  bitsetv_free (LA);

 }
 }