Merge remote-tracking branch 'origin/maint'

[bison.git] / src / lalr.c

diff --git a/src/lalr.c b/src/lalr.c
index c6d3f5c3874c7ec82e1beba84f3559f1f0f8e7f2..1ceda002b454fcddd9993da74c665c3d3f84040f 100644 (file)
--- a/src/lalr.c
+++ b/src/lalr.c
@@ -1,682 +1,500 @@
-/* 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, 2000-2012 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 "types.h"
+
+#include <bitset.h>
+#include <bitsetv.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"
+#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
+{
+  struct goto_list *next;
+  goto_number value;
+} goto_list;

 
 

-/* 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;
+/* 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.  */

 
 

-short *goto_map;
-short *from_state;
-short *to_state;
+static bitsetv LA = NULL;
+size_t nLA;

 
 

-extern void berror PARAMS ((const char *));

 
 

-static int infinity;
-static int ngotos;
+static goto_number **includes;
+static goto_list **lookback;

 
 

-/* 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)
+void
+set_goto_map (void)

 {
 {

-  unsigned *fp1;
-  unsigned *fp2;
-  unsigned *fp3;
-  int j;
-  short *rp;
+  state_number s;
+  goto_number *temp_map;

 
 

-  int height;
-  unsigned *base;
+  goto_map = xcalloc (nvars + 1, sizeof *goto_map);
+  temp_map = xnmalloc (nvars + 1, sizeof *temp_map);

 
 

-  VERTICES[++top] = i;
-  INDEX[i] = height = top;
-
-  base = F (i);
-  fp3 = F (i + 1);
-
-  rp = R[i];
-  if (rp)
+  ngotos = 0;
+  for (s = 0; s < nstates; ++s)

     {
     {

-      while ((j = *rp++) >= 0)
-       {
-         if (INDEX[j] == 0)
-           traverse (j);
+      transitions *sp = states[s]->transitions;
+      int i;
+      for (i = sp->num - 1; i >= 0 && TRANSITION_IS_GOTO (sp, i); --i)
+        {
+          ngotos++;

 
 

-         if (INDEX[i] > INDEX[j])
-           INDEX[i] = INDEX[j];
+          /* Abort if (ngotos + 1) would overflow.  */
+          aver (ngotos != GOTO_NUMBER_MAXIMUM);

 
 

-         fp1 = base;
-         fp2 = F (j);
-
-         while (fp1 < fp3)
-           *fp1++ |= *fp2++;
-       }
+          goto_map[TRANSITION_SYMBOL (sp, i) - ntokens]++;
+        }

     }
 
     }
 

-  if (INDEX[i] == height)
-    {
-      for (;;)
-       {
-         j = VERTICES[top--];
-         INDEX[j] = infinity;
-
-         if (i == j)
-           break;
-
-         fp1 = base;
-         fp2 = F (j);
-
-         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)
-{
-  /* 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)
+    goto_number k = 0;
+    int i;
+    for (i = ntokens; i < nsyms; i++)

       {
       {

-       state_table[sp->number].state = sp;
-       state_table[sp->number].accessing_symbol = sp->accessing_symbol;
+        temp_map[i - ntokens] = k;
+        k += goto_map[i - ntokens];

       }
       }

-  }

 
 

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

 
 

-  /* 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;
+    goto_map[nsyms - ntokens] = ngotos;
+    temp_map[nsyms - ntokens] = ngotos;

   }
   }

-}

 
 

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

 
 

-/* 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++)
+  for (s = 0; s < nstates; ++s)

     {
     {

-      if (*itemp > 0)
-       {
-         length++;
-       }
-      else
-       {
-         if (length > max)
-           max = length;
-         length = 0;
-       }
+      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;
+        }

     }
 
     }
 

-  return max;
+  free (temp_map);

 }
 
 
 }
 
 

-static void
-initialize_LA (void)
+goto_number
+map_goto (state_number s0, symbol_number sym)

 {
 {

-  int i;
-  int j;
-  short *np;
-  reductions *rp;
+  goto_number high;
+  goto_number low;
+  goto_number middle;
+  state_number s;

 
 

-  size_t nLA = state_table[nstates].lookaheads;
-  if (!nLA)
-    nLA = 1;
-
-  LA = XCALLOC (unsigned, nLA * tokensetsize);
-  LAruleno = XCALLOC (short, nLA);
-  lookback = XCALLOC (shorts *, nLA);
+  low = goto_map[sym - ntokens];
+  high = goto_map[sym - ntokens + 1] - 1;

 
 

-  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];
+  for (;;)
+    {
+      aver (low <= high);
+      middle = (low + high) / 2;
+      s = from_state[middle];
+      if (s == s0)
+        return middle;
+      else if (s < s0)
+        low = middle + 1;
+      else
+        high = middle - 1;
+    }

 }
 
 
 static void
 }
 
 
 static void

-set_goto_map (void)
+initialize_F (void)

 {
 {

-  shifts *sp;
-  int i;
-  int symbol;
-  int k;
-  short *temp_map;
-  int state2;
-  int state1;
-
-  goto_map = XCALLOC (short, nvars + 1) - ntokens;
-  temp_map = XCALLOC (short, nvars + 1) - ntokens;
-
-  ngotos = 0;
-  for (sp = first_shift; sp; sp = sp->next)
-    {
-      for (i = sp->nshifts - 1; i >= 0; i--)
-       {
-         symbol = state_table[sp->shifts[i]].accessing_symbol;
+  goto_number **reads = xnmalloc (ngotos, sizeof *reads);
+  goto_number *edge = xnmalloc (ngotos + 1, sizeof *edge);
+  goto_number nedges = 0;

 
 

-         if (ISTOKEN (symbol))
-           break;
+  goto_number i;

 
 

-         if (ngotos == MAXSHORT)
-           fatal (_("too many gotos (max %d)"), MAXSHORT);
+  goto_follows = bitsetv_create (ngotos, ntokens, BITSET_FIXED);

 
 

-         ngotos++;
-         goto_map[symbol]++;
-       }
-    }
-
-  k = 0;
-  for (i = ntokens; i < nsyms; i++)
+  for (i = 0; i < ngotos; i++)

     {
     {

-      temp_map[i] = k;
-      k += goto_map[i];
+      state_number stateno = to_state[i];
+      transitions *sp = states[stateno]->transitions;
+
+      int j;
+      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;
+        }

     }
 
     }
 

-  for (i = ntokens; i < nsyms; i++)
-    goto_map[i] = temp_map[i];
+  relation_digraph (reads, ngotos, &goto_follows);

 
 

-  goto_map[nsyms] = ngotos;
-  temp_map[nsyms] = ngotos;
+  for (i = 0; i < ngotos; i++)
+    free (reads[i]);

 
 

-  from_state = XCALLOC (short, ngotos);
-  to_state = XCALLOC (short, ngotos);
+  free (reads);
+  free (edge);
+}

 
 

-  for (sp = first_shift; sp; sp = sp->next)
-    {
-      state1 = sp->number;
-      for (i = sp->nshifts - 1; i >= 0; 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;
-       }
-    }

 
 

-  XFREE (temp_map + ntokens);
+static void
+add_lookback_edge (state *s, rule *r, goto_number gotono)
+{
+  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;
+  lookback[(s->reductions->lookahead_tokens - LA) + ri] = sp;

 }
 
 
 
 }
 
 
 

-/*----------------------------------------------------------.
-| Map a state/symbol pair into its numeric representation.  |
-`----------------------------------------------------------*/
-
-static int
-map_goto (int state, int symbol)
+static void
+build_relations (void)

 {
 {

-  int high;
-  int low;
-  int middle;
-  int s;
+  goto_number *edge = xnmalloc (ngotos + 1, sizeof *edge);
+  state_number *states1 = xnmalloc (ritem_longest_rhs () + 1, sizeof *states1);
+  goto_number i;

 
 

-  low = goto_map[symbol];
-  high = goto_map[symbol + 1] - 1;
+  includes = xnmalloc (ngotos, sizeof *includes);

 
 

-  while (low <= high)
+  for (i = 0; i < ngotos; i++)

     {
     {

-      middle = (low + high) / 2;
-      s = from_state[middle];
-      if (s == state)
-       return middle;
-      else if (s < state)
-       low = middle + 1;
+      int nedges = 0;
+      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
       else

-       high = middle - 1;
+        {
+          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;
+        }

     }
 
     }
 

-  assert (0);
-  /* NOTREACHED */
-  return 0;
+  free (edge);
+  free (states1);
+
+  relation_transpose (&includes, ngotos);

 }
 
 
 }
 
 

+

 static void
 static void

-initialize_F (void)
+compute_FOLLOWS (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;
-
-         for (j = 0; j < k; j++)
-           {
-             symbol = state_table[sp->shifts[j]].accessing_symbol;
-             if (ISVAR (symbol))
-               break;
-             SETBIT (rowp, symbol);
-           }
-
-         for (; j < k; j++)
-           {
-             symbol = state_table[sp->shifts[j]].accessing_symbol;
-             if (nullable[symbol])
-               edge[nedges++] = map_goto (stateno, symbol);
-           }
-
-         if (nedges)
-           {
-             reads[i] = rp = XCALLOC (short, nedges + 1);
-
-             for (j = 0; j < nedges; j++)
-               rp[j] = edge[j];
-
-             rp[nedges] = -1;
-             nedges = 0;
-           }
-       }
-
-      rowp += tokensetsize;
-    }
+  goto_number i;

 
 

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

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

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

 
 

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

 }
 
 
 static void
 }
 
 
 static void

-add_lookback_edge (int stateno, int ruleno, int gotono)
+compute_lookahead_tokens (void)

 {
 {

-  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++;
-    }
+  size_t i;
+  goto_list *sp;

 
 

-  assert (found);
+  for (i = 0; i < nLA; i++)
+    for (sp = lookback[i]; sp; sp = sp->next)
+      bitset_or (LA[i], LA[i], goto_follows[sp->value]);

 
 

-  sp = XCALLOC (shorts, 1);
-  sp->next = lookback[i];
-  sp->value = gotono;
-  lookback[i] = sp;
+  /* Free LOOKBACK. */
+  for (i = 0; i < nLA; i++)
+    LIST_FREE (goto_list, lookback[i]);
+
+  free (lookback);

 }
 
 
 }
 
 

-static short **
-transpose (short **R_arg, int n)
+/*----------------------------------------------------.
+| 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)

 {
 {

-  short **new_R;
-  short **temp_R;
-  short *nedges;
-  short *sp;
-  int i;
-  int k;
+  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;
+}

 
 

-  nedges = XCALLOC (short, n);

 
 

-  for (i = 0; i < n; i++)
-    {
-      sp = R_arg[i];
-      if (sp)
-       {
-         while (*sp >= 0)
-           nedges[*sp++]++;
-       }
-    }
+/*----------------------------------------------------.
+| Compute LA, NLA, and the lookahead_tokens members.  |
+`----------------------------------------------------*/

 
 

-  new_R = XCALLOC (short *, n);
-  temp_R = XCALLOC (short *, n);
+void
+initialize_LA (void)
+{
+  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 = STREQ (default_reductions, "accepting");
+    free (default_reductions);
+  }

 
 

-  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;
-       }
-    }
+  /* 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;

 
 

-  XFREE (nedges);
+  pLA = LA = bitsetv_create (nLA, ntokens, BITSET_FIXED);

 
 

-  for (i = 0; i < n; i++)
+  /* Initialize the members LOOKAHEAD_TOKENS for each state whose reductions
+     require lookahead tokens.  */
+  for (i = 0; i < nstates; i++)

     {
     {

-      sp = R_arg[i];
-      if (sp)
-       {
-         while (*sp >= 0)
-           *temp_R[*sp++]++ = i;
-       }
+      int count =
+        state_lookahead_tokens_count (states[i],
+                                      default_reduction_only_for_accept);
+      if (count)
+        {
+          states[i]->reductions->lookahead_tokens = pLA;
+          pLA += count;
+        }

     }
     }

-
-  XFREE (temp_R);
-
-  return new_R;

 }
 
 
 }
 
 

+/*---------------------------------------------.
+| Output the lookahead tokens for each state.  |
+`---------------------------------------------*/
+

 static void
 static void

-build_relations (void)
+lookahead_tokens_print (FILE *out)

 {
 {

-  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);
-
-  for (i = 0; i < ngotos; i++)
+  state_number i;
+  int j, k;
+  fprintf (out, "Lookahead tokens: BEGIN\n");
+  for (i = 0; i < nstates; ++i)

     {
     {

-      nedges = 0;
-      state1 = from_state[i];
-      symbol1 = state_table[to_state[i]].accessing_symbol;
-
-      for (rulep = derives[symbol1]; *rulep > 0; rulep++)
-       {
-         length = 1;
-         states[0] = state1;
-         stateno = state1;
-
-         for (rp = ritem + rrhs[*rulep]; *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;
-           }
-
-         if (!state_table[stateno].consistent)
-           add_lookback_edge (stateno, *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))
-               {
-                 stateno = states[--length];
-                 edge[nedges++] = map_goto (stateno, *rp);
-                 if (nullable[*rp])
-                   done = 0;
-               }
-           }
-       }
-
-      if (nedges)
-       {
-         includes[i] = shortp = XCALLOC (short, nedges + 1);
-         for (j = 0; j < nedges; j++)
-           shortp[j] = edge[j];
-         shortp[nedges] = -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);
+          };

     }
     }

-
-  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 (states);
+  fprintf (out, "Lookahead tokens: END\n");

 }
 
 }
 

-
-
-static void
-compute_FOLLOWS (void)
+void
+lalr (void)

 {
 {

-  int i;
-
-  digraph (includes);
-
-  for (i = 0; i < ngotos; i++)
-    XFREE (includes[i]);
+  initialize_LA ();
+  set_goto_map ();
+  initialize_F ();
+  lookback = xcalloc (nLA, sizeof *lookback);
+  build_relations ();
+  compute_FOLLOWS ();
+  compute_lookahead_tokens ();

 
 

-  XFREE (includes);
+  if (trace_flag & trace_sets)
+    lookahead_tokens_print (stderr);

 }
 
 
 }
 
 

-static void
-compute_lookaheads (void)
+void
+lalr_update_state_numbers (state_number old_to_new[], state_number nstates_old)

 {
 {

-  int i;
-  shorts *sp;
-
-  for (i = 0; i < state_table[nstates].lookaheads; i++)
-    for (sp = lookback[i]; sp; sp = sp->next)
+  goto_number ngotos_reachable = 0;
+  symbol_number nonterminal = 0;
+  aver (nsyms == nvars + ntokens);
+  {
+    goto_number i;
+    for (i = 0; i < ngotos; ++i)

       {
       {

-       unsigned *fp1 = LA (i);
-       unsigned *fp2 = F (sp->value);
-       while (fp1 < LA (i + 1))
-         *fp1++ |= *fp2++;
+        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;
+          }

       }
       }

-
-  /* Free LOOKBACK. */
-  for (i = 0; i < state_table[nstates].lookaheads; i++)
+  }
+  while (nonterminal <= nvars)

     {
     {

-      shorts *sptmp;
-      for (sp = lookback[i]; sp; sp = sptmp)
-       {
-         sptmp = sp->next;
-         XFREE (sp);
-       }
+      aver (ngotos == goto_map[nonterminal]);
+      goto_map[nonterminal++] = ngotos_reachable;

     }
     }

-
-  XFREE (lookback);
-  XFREE (F);
+  ngotos = ngotos_reachable;

 }
 
 
 void
 }
 
 
 void

-lalr (void)
+lalr_free (void)

 {
 {

-  tokensetsize = WORDSIZE (ntokens);
-
-  set_state_table ();
-  initialize_LA ();
-  set_goto_map ();
-  initialize_F ();
-  build_relations ();
-  compute_FOLLOWS ();
-  compute_lookaheads ();
+  state_number s;
+  for (s = 0; s < nstates; ++s)
+    states[s]->reductions->lookahead_tokens = NULL;
+  bitsetv_free (LA);

 }
 }