build: be sure to include config.h first in the generated parser

[bison.git] / src / lalr.c

diff --git a/src/lalr.c b/src/lalr.c
index 9dda7f05647331a319e6d8ff7a9b24d7ac7d42a5..d99f960fbf903fdad47f62580fb79695c829ffe1 100644 (file)
--- a/src/lalr.c
+++ b/src/lalr.c
@@ -1,472 +1,289 @@
-/* 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, 2000-2013 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
+/* Find which rules need lookahead in each state, and which lookahead

    tokens they accept.  */
 
    tokens they accept.  */
 

+#include <config.h>

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

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

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

-#include "symtab.h"
-#include "gram.h"

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

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

 #include "derives.h"
 #include "getargs.h"
 #include "derives.h"
 #include "getargs.h"

+#include "gram.h"
+#include "lalr.h"
+#include "muscle-tab.h"
+#include "nullable.h"
+#include "reader.h"
+#include "relation.h"
+#include "symtab.h"

 
 

-/* All the decorated states, indexed by the state number.  */
-state_t **states = NULL;
-
-short *LAruleno = NULL;
-bitset *LA = NULL;
-size_t nLA;
-
-static int ngotos;
-short *goto_map = NULL;
-short *from_state = NULL;
-short *to_state = NULL;
-
-/* And for the famous F variable, which name is so descriptive that a
-   comment is hardly needed.  <grin>.  */
-static bitset *F = NULL;
-
-static short **includes;
-static shorts **lookback;
-
-
-/*---------------------------------------------------------------.
-| digraph & traverse.                                            |
-|                                                                |
-| The following variables are used as common storage between the |
-| two.                                                           |
-`---------------------------------------------------------------*/
-
-static short **R;
-static short *INDEX;
-static short *VERTICES;
-static int top;
-static int infinity;
-
-static void
-traverse (int i)
-{
-  int j;
-  int height;
-
-  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]];
-
-       bitset_or (F[i], F[i], F[R[i][j]]);
-      }
-
-  if (INDEX[i] == height)
-    for (;;)
-      {
-       j = VERTICES[top--];
-       INDEX[j] = infinity;
-
-       if (i == j)
-         break;
-
-       bitset_copy (F[j], F[i]);
-      }
-}
-
+goto_number *goto_map;
+goto_number ngotos;
+state_number *from_state;
+state_number *to_state;
+bitsetv goto_follows = NULL;

 
 

-static void
-digraph (short **relation)
+/* Linked list of goto numbers.  */
+typedef struct goto_list

 {
 {

-  int i;
-
-  infinity = ngotos + 2;
-  INDEX = XCALLOC (short, ngotos + 1);
-  VERTICES = XCALLOC (short, ngotos + 1);
-  top = 0;
-
-  R = relation;
+  struct goto_list *next;
+  goto_number value;
+} goto_list;

 
 

-  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);
-}
+/* 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.  */

 
 

+static bitsetv LA = NULL;
+size_t nLA;

 
 

-static void
-initialize_LA (void)
-{
-  size_t i;
-  int j;
-  short *np;

 
 

-  /* Avoid having to special case 0.  */
-  if (!nLA)
-    nLA = 1;
+static goto_number **includes;
+static goto_list **lookback;

 
 

-  LA = XCALLOC (bitset, nLA);
-  for (i = 0; i < nLA; ++i)
-    LA[i] = bitset_create (ntokens, BITSET_FIXED);
-  LAruleno = XCALLOC (short, nLA);
-  lookback = XCALLOC (shorts *, nLA);

 
 

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

 
 
 
 

-static void
+void

 set_goto_map (void)
 {
 set_goto_map (void)
 {

-  size_t state;
-  int i;
-  short *temp_map;
+  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 (state = 0; state < nstates; ++state)
+  for (s = 0; s < nstates; ++s)

     {
     {

-      shifts *sp = states[state]->shifts;
-      for (i = sp->nshifts - 1; i >= 0 && SHIFT_IS_GOTO (sp, i); --i)
-       {
-         if (ngotos == MAXSHORT)
-           fatal (_("too many gotos (max %d)"), MAXSHORT);
-
-         ngotos++;
-         goto_map[SHIFT_SYMBOL (sp, i)]++;
-       }
+      transitions *sp = states[s]->transitions;
+      int i;
+      for (i = sp->num - 1; i >= 0 && TRANSITION_IS_GOTO (sp, i); --i)
+        {
+          ngotos++;
+
+          /* Abort if (ngotos + 1) would overflow.  */
+          aver (ngotos != GOTO_NUMBER_MAXIMUM);
+
+          goto_map[TRANSITION_SYMBOL (sp, i) - ntokens]++;
+        }

     }
 
   {
     }
 
   {

-    int k = 0;
+    goto_number k = 0;
+    int i;

     for (i = ntokens; i < nsyms; i++)
       {
     for (i = ntokens; i < nsyms; i++)
       {

-       temp_map[i] = k;
-       k += goto_map[i];
+        temp_map[i - ntokens] = k;
+        k += goto_map[i - ntokens];

       }
 
     for (i = ntokens; i < nsyms; i++)
       }
 
     for (i = ntokens; i < nsyms; i++)

-      goto_map[i] = temp_map[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 (state = 0; state < nstates; ++state)
+  for (s = 0; s < nstates; ++s)

     {
     {

-      shifts *sp = states[state]->shifts;
-      for (i = sp->nshifts - 1; i >= 0 && SHIFT_IS_GOTO (sp, i); --i)
-       {
-         int k = temp_map[SHIFT_SYMBOL (sp, i)]++;
-         from_state[k] = state;
-         to_state[k] = sp->shifts[i];
-       }
+      transitions *sp = states[s]->transitions;
+      int i;
+      for (i = sp->num - 1; i >= 0 && TRANSITION_IS_GOTO (sp, i); --i)
+        {
+          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)
-       return middle;
-      else if (s < state)
-       low = middle + 1;
+      if (s == s0)
+        return middle;
+      else if (s < s0)
+        low = middle + 1;

       else
       else

-       high = middle - 1;
+        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 (bitset, ngotos);
-  for (i = 0; i < ngotos; ++i)
-    F[i] = bitset_create (ntokens, BITSET_FIXED);
+  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 = states[stateno]->shifts;
+      state_number stateno = to_state[i];
+      transitions *sp = states[stateno]->transitions;

 
       int j;
 
       int j;

-      for (j = 0; j < sp->nshifts && SHIFT_IS_SHIFT (sp, j); j++)
-       bitset_set (F[i], SHIFT_SYMBOL (sp, j));
-
-      for (; j < sp->nshifts; j++)
-       {
-         int symbol = SHIFT_SYMBOL (sp, j);
-         if (nullable[symbol])
-           edge[nedges++] = map_goto (stateno, symbol);
-       }
-
-      if (nedges)
-       {
-         reads[i] = XCALLOC (short, nedges + 1);
-         shortcpy (reads[i], edge, nedges);
-         reads[i][nedges] = -1;
-         nedges = 0;
-       }
+      FOR_EACH_SHIFT (sp, j)
+        bitset_set (goto_follows[i], TRANSITION_SYMBOL (sp, j));
+
+      for (; j < sp->num; j++)
+        {
+          symbol_number sym = TRANSITION_SYMBOL (sp, j);
+          if (nullable[sym - ntokens])
+            edge[nedges++] = map_goto (stateno, sym);
+        }
+
+      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 (state_t *state, int ruleno, int gotono)
+add_lookback_edge (state *s, rule *r, goto_number gotono)

 {
 {

-  int i;
-  shorts *sp;
-
-  for (i = 0; i < state->nlookaheads; ++i)
-    if (LAruleno[state->lookaheadsp + i] == ruleno)
-      break;
-
-  assert (LAruleno[state->lookaheadsp + i] == ruleno);
-
-  sp = XCALLOC (shorts, 1);
-  sp->next = lookback[state->lookaheadsp + 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[state->lookaheadsp + i] = sp;
-}
-
-
-static void
-matrix_print (FILE *out, short **matrix, int n)
-{
-  int i, j;
-
-  for (i = 0; i < n; ++i)
-    {
-      fprintf (out, "%3d: ", i);
-      if (matrix[i])
-       for (j = 0; matrix[i][j] != -1; ++j)
-         fprintf (out, "%3d ", matrix[i][j]);
-      fputc ('\n', out);
-    }
-  fputc ('\n', out);
+  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.                                          |
-|                                                                    |
-| R_ARG[I] is NULL or a -1 terminated list of numbers.               |
-|                                                                    |
-| RESULT[NUM] is NULL or the -1 terminated list of the I such as NUM |
-| is in R_ARG[I].                                                    |
-`-------------------------------------------------------------------*/
-
-static short **
-transpose (short **R_arg, int n)
-{
-  /* The result. */
-  short **new_R = XCALLOC (short *, n);
-  /* END_R[I] -- next entry of NEW_R[I]. */
-  short **end_R = XCALLOC (short *, n);
-  /* NEDGES[I] -- total size of NEW_R[I]. */
-  short *nedges = XCALLOC (short, n);
-  int i, j;
-
-  if (trace_flag)
-    {
-      fputs ("transpose: input\n", stderr);
-      matrix_print (stderr, R_arg, n);
-    }
-
-  /* Count. */
-  for (i = 0; i < n; i++)
-    if (R_arg[i])
-      for (j = 0; R_arg[i][j] >= 0; ++j)
-       ++nedges[R_arg[i][j]];
-
-  /* Allocate. */
-  for (i = 0; i < n; i++)
-    if (nedges[i] > 0)
-      {
-       short *sp = XCALLOC (short, nedges[i] + 1);
-       sp[nedges[i]] = -1;
-       new_R[i] = sp;
-       end_R[i] = sp;
-      }
-
-  /* Store. */
-  for (i = 0; i < n; i++)
-    if (R_arg[i])
-      for (j = 0; R_arg[i][j] >= 0; ++j)
-       {
-         *end_R[R_arg[i][j]] = i;
-         ++end_R[R_arg[i][j]];
-       }
-
-  free (nedges);
-  free (end_R);
-
-  /* Free the input: it is replaced with the result. */
-  for (i = 0; i < n; i++)
-    XFREE (R_arg[i]);
-  free (R_arg);
-
-  if (trace_flag)
-    {
-      fputs ("transpose: output\n", stderr);
-      matrix_print (stderr, new_R, n);
-    }
-
-  return new_R;
-}

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

-  short *edge = XCALLOC (short, ngotos + 1);
-  short *states1 = 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 symbol1 = states[to_state[i]]->accessing_symbol;
-      short *rulep;
-
-      for (rulep = derives[symbol1]; *rulep > 0; rulep++)
-       {
-         int done;
-         int length = 1;
-         short *rp;
-         state_t *state = states[from_state[i]];
-         states1[0] = state->number;
-
-         for (rp = &ritem[rules[*rulep].rhs]; *rp >= 0; rp++)
-           {
-             shifts *sp = state->shifts;
-             int j;
-             for (j = 0; j < sp->nshifts; j++)
-               {
-                 state = states[sp->shifts[j]];
-                 if (state->accessing_symbol == *rp)
-                   break;
-               }
-
-             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))
-               {
-                 edge[nedges++] = map_goto (states1[--length], *rp);
-                 if (nullable[*rp])
-                   done = 0;
-               }
-           }
-       }
-
-      if (nedges)
-       {
-         int j;
-         includes[i] = XCALLOC (short, nedges + 1);
-         for (j = 0; j < nedges; j++)
-           includes[i][j] = edge[j];
-         includes[i][nedges] = -1;
-       }
+      symbol_number symbol1 = states[to_state[i]]->accessing_symbol;
+      rule **rulep;
+
+      for (rulep = derives[symbol1 - ntokens]; *rulep; rulep++)
+        {
+          bool done;
+          int length = 1;
+          item_number const *rp;
+          state *s = states[from_state[i]];
+          states1[0] = s->number;
+
+          for (rp = (*rulep)->rhs; ! item_number_is_rule_number (*rp); rp++)
+            {
+              s = transitions_to (s->transitions,
+                                  item_number_as_symbol_number (*rp));
+              states1[length++] = s->number;
+            }
+
+          if (!s->consistent)
+            add_lookback_edge (s, *rulep, i);
+
+          length--;
+          done = false;
+          while (!done)
+            {
+              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--;
+              if (ISVAR (*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 = false;
+                }
+            }
+        }
+
+      if (nedges == 0)
+        includes[i] = NULL;
+      else
+        {
+          int j;
+          includes[i] = xnmalloc (nedges + 1, sizeof includes[i][0]);
+          for (j = 0; j < nedges; j++)
+            includes[i][j] = edge[j];
+          includes[i][nedges] = END_NODE;
+        }

     }
 
     }
 

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

 
 

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

 }
 
 
 }
 
 


@@ -474,114 +291,210 @@ 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)

 {
   size_t i;
 {
   size_t i;

-  shorts *sp;
+  goto_list *sp;

 
   for (i = 0; i < nLA; i++)
     for (sp = lookback[i]; sp; sp = sp->next)
 
   for (i = 0; i < nLA; i++)
     for (sp = lookback[i]; sp; sp = sp->next)

-      bitset_or (LA[i], LA[i], F[sp->value]);
+      bitset_or (LA[i], LA[i], goto_follows[sp->value]);

 
   /* Free LOOKBACK. */
   for (i = 0; i < nLA; i++)
 
   /* Free LOOKBACK. */
   for (i = 0; i < nLA; i++)

-    LIST_FREE (shorts, lookback[i]);
+    LIST_FREE (goto_list, lookback[i]);

 
 

-  XFREE (lookback);
-  for (i = 0; i < (unsigned) ngotos; ++i)
-    bitset_free (F[i]);
-  XFREE (F);
+  free (lookback);

 }
 
 
 }
 
 

-/*--------------------------------------.
-| Initializing the lookaheads members.  |
-`--------------------------------------*/
+/*----------------------------------------------------.
+| Count the number of lookahead tokens required for S |
+| (N_LOOKAHEAD_TOKENS member).                        |
+`----------------------------------------------------*/

 
 

-static void
-initialize_lookaheads (void)
+static int
+state_lookahead_tokens_count (state *s, bool default_reduction_only_for_accept)

 {
 {

-  size_t i;
+  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
+initialize_LA (void)
+{
+  state_number i;
+  bitsetv pLA;
+  bool default_reduction_only_for_accept;
+  {
+    char *default_reductions =
+      muscle_percent_define_get ("lr.default-reduction");
+    default_reduction_only_for_accept = STREQ (default_reductions, "accepting");
+    free (default_reductions);
+  }
+
+  /* Compute the total number of reductions requiring a lookahead.  */

   nLA = 0;
   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;
+
+  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++)
     {
   for (i = 0; i < nstates; i++)
     {

-      int k;
-      int nlookaheads = 0;
-      reductions *rp = states[i]->reductions;
-      shifts *sp = states[i]->shifts;
-
-      /* 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->nreds > 1
-         || (rp->nreds == 1 && sp->nshifts && SHIFT_IS_SHIFT (sp, 0)))
-       nlookaheads += rp->nreds;
-      else
-       states[i]->consistent = 1;
-
-      for (k = 0; k < sp->nshifts; k++)
-       if (SHIFT_IS_ERROR (sp, k))
-         {
-           states[i]->consistent = 0;
-           break;
-         }
-
-      states[i]->nlookaheads = nlookaheads;
-      states[i]->lookaheadsp = nLA;
-      nLA += nlookaheads;
+      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 lookaheads for each state.  |
-`---------------------------------------*/
+/*---------------------------------------------.
+| Output the lookahead tokens for each state.  |
+`---------------------------------------------*/

 
 static void
 
 static void

-lookaheads_print (FILE *out)
+lookahead_tokens_print (FILE *out)

 {
 {

-  size_t i;
+  state_number i;

   int j, k;
   int j, k;

-  fprintf (out, "Lookaheads: BEGIN\n");
+  fprintf (out, "Lookahead tokens: BEGIN\n");

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

-      fprintf (out, "State %d: %d lookaheads\n",
-              i, states[i]->nlookaheads);
-
-      for (j = 0; j < states[i]->nlookaheads; ++j)
-       for (k = 0; k < ntokens; ++k)
-         if (bitset_test (LA[states[i]->lookaheadsp + j], j))
-           fprintf (out, "   on %d (%s) -> rule %d\n",
-                    k, symbols[k]->tag,
-                    -LAruleno[states[i]->lookaheadsp + j] - 1);
+      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, "Lookaheads: END\n");
+  fprintf (out, "Lookahead tokens: END\n");

 }
 
 void
 lalr (void)
 {
 }
 
 void
 lalr (void)
 {

-  initialize_lookaheads ();

   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)
-    lookaheads_print (stderr);
+  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);

 }
 }