muscle: factor the computation of variable names

[bison.git] / src / lalr.c

diff --git a/src/lalr.c b/src/lalr.c
index 805797cf334b7299ab65e7c7c4d84e053f2e9bfc..d99f960fbf903fdad47f62580fb79695c829ffe1 100644 (file)
--- a/src/lalr.c
+++ b/src/lalr.c
@@ -1,28 +1,25 @@
 /* Compute lookahead criteria for Bison.
 
 /* Compute lookahead criteria for Bison.
 

-   Copyright (C) 1984, 1986, 1989, 2000, 2001, 2002, 2003, 2004, 2005,
-   2006 Free Software Foundation, Inc.
+   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., 51 Franklin Street, Fifth Floor,
-   Boston, MA 02110-1301, 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.  */
 
 #include <config.h>
    tokens they accept.  */
 
 #include <config.h>


@@ -30,7 +27,6 @@
 
 #include <bitset.h>
 #include <bitsetv.h>
 
 #include <bitset.h>
 #include <bitsetv.h>

-#include <quotearg.h>

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


@@ -38,15 +34,17 @@
 #include "getargs.h"
 #include "gram.h"
 #include "lalr.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"
 
 goto_number *goto_map;
 #include "nullable.h"
 #include "reader.h"
 #include "relation.h"
 #include "symtab.h"
 
 goto_number *goto_map;

-static goto_number ngotos;
+goto_number ngotos;

 state_number *from_state;
 state_number *to_state;
 state_number *from_state;
 state_number *to_state;

+bitsetv goto_follows = NULL;

 
 /* Linked list of goto numbers.  */
 typedef struct goto_list
 
 /* Linked list of goto numbers.  */
 typedef struct goto_list


@@ -65,17 +63,13 @@ static bitsetv LA = NULL;
 size_t nLA;
 
 
 size_t nLA;
 
 

-/* And for the famous F variable, which name is so descriptive that a
-   comment is hardly needed.  <grin>.  */
-static bitsetv F = NULL;
-

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

-static void
+void

 set_goto_map (void)
 {
   state_number s;
 set_goto_map (void)
 {
   state_number s;


@@ -90,14 +84,14 @@ set_goto_map (void)
       transitions *sp = states[s]->transitions;
       int i;
       for (i = sp->num - 1; i >= 0 && TRANSITION_IS_GOTO (sp, i); --i)
       transitions *sp = states[s]->transitions;
       int i;
       for (i = sp->num - 1; i >= 0 && TRANSITION_IS_GOTO (sp, i); --i)

-       {
-         ngotos++;
+        {
+          ngotos++;

 
 

-         /* Abort if (ngotos + 1) would overflow.  */
-         aver (ngotos != GOTO_NUMBER_MAXIMUM);
+          /* Abort if (ngotos + 1) would overflow.  */
+          aver (ngotos != GOTO_NUMBER_MAXIMUM);

 
 

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

     }
 
   {
     }
 
   {


@@ -105,8 +99,8 @@ set_goto_map (void)
     int i;
     for (i = ntokens; i < nsyms; i++)
       {
     int i;
     for (i = ntokens; i < nsyms; i++)
       {

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

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


@@ -124,23 +118,18 @@ set_goto_map (void)
       transitions *sp = states[s]->transitions;
       int i;
       for (i = sp->num - 1; i >= 0 && TRANSITION_IS_GOTO (sp, i); --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;
-       }
+        {
+          goto_number k = temp_map[TRANSITION_SYMBOL (sp, i) - ntokens]++;
+          from_state[k] = s;
+          to_state[k] = sp->states[i]->number;
+        }

     }
 
   free (temp_map);
 }
 
 
     }
 
   free (temp_map);
 }
 
 

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

 map_goto (state_number s0, symbol_number sym)
 {
   goto_number high;
 map_goto (state_number s0, symbol_number sym)
 {
   goto_number high;


@@ -157,11 +146,11 @@ map_goto (state_number s0, symbol_number sym)
       middle = (low + high) / 2;
       s = from_state[middle];
       if (s == s0)
       middle = (low + high) / 2;
       s = from_state[middle];
       if (s == s0)

-       return middle;
+        return middle;

       else if (s < s0)
       else if (s < s0)

-       low = middle + 1;
+        low = middle + 1;

       else
       else

-       high = middle - 1;
+        high = middle - 1;

     }
 }
 
     }
 }
 


@@ -175,7 +164,7 @@ initialize_F (void)
 
   goto_number i;
 
 
   goto_number i;
 

-  F = bitsetv_create (ngotos, ntokens, BITSET_FIXED);
+  goto_follows = bitsetv_create (ngotos, ntokens, BITSET_FIXED);

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


@@ -184,27 +173,27 @@ initialize_F (void)
 
       int j;
       FOR_EACH_SHIFT (sp, j)
 
       int j;
       FOR_EACH_SHIFT (sp, j)

-       bitset_set (F[i], TRANSITION_SYMBOL (sp, j));
+        bitset_set (goto_follows[i], TRANSITION_SYMBOL (sp, j));

 
       for (; j < sp->num; j++)
 
       for (; j < sp->num; j++)

-       {
-         symbol_number sym = TRANSITION_SYMBOL (sp, j);
-         if (nullable[sym - ntokens])
-           edge[nedges++] = map_goto (stateno, sym);
-       }
+        {
+          symbol_number sym = TRANSITION_SYMBOL (sp, j);
+          if (nullable[sym - ntokens])
+            edge[nedges++] = map_goto (stateno, sym);
+        }

 
       if (nedges == 0)
 
       if (nedges == 0)

-       reads[i] = NULL;
+        reads[i] = NULL;

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

     }
 
     }
 

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

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


@@ -242,53 +231,53 @@ build_relations (void)
       rule **rulep;
 
       for (rulep = derives[symbol1 - ntokens]; *rulep; rulep++)
       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 an item number, and there is a
-                sentinel 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;
-               }
-           }
-       }
+        {
+          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)
 
       if (nedges == 0)

-       includes[i] = NULL;
+        includes[i] = NULL;

       else
       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;
-       }
+        {
+          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;
+        }

     }
 
   free (edge);
     }
 
   free (edge);


@@ -304,7 +293,7 @@ compute_FOLLOWS (void)
 {
   goto_number i;
 
 {
   goto_number i;
 

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

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


@@ -321,14 +310,13 @@ compute_lookahead_tokens (void)
 
   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++)
     LIST_FREE (goto_list, lookback[i]);
 
   free (lookback);
 
   /* Free LOOKBACK. */
   for (i = 0; i < nLA; i++)
     LIST_FREE (goto_list, lookback[i]);
 
   free (lookback);

-  bitsetv_free (F);

 }
 
 
 }
 
 


@@ -338,31 +326,35 @@ compute_lookahead_tokens (void)
 `----------------------------------------------------*/
 
 static int
 `----------------------------------------------------*/
 
 static int

-state_lookahead_tokens_count (state *s)
+state_lookahead_tokens_count (state *s, bool default_reduction_only_for_accept)

 {
 {

-  int k;

   int n_lookahead_tokens = 0;
   reductions *rp = s->reductions;
   transitions *sp = s->transitions;
 
   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'.  */
+  /* 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
   if (rp->num > 1

-      || (rp->num == 1 && sp->num &&
-         !TRANSITION_IS_DISABLED (sp, 0) && TRANSITION_IS_SHIFT (sp, 0)))
+      || (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;
 
     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;
 }
 
   return n_lookahead_tokens;
 }
 


@@ -371,33 +363,43 @@ state_lookahead_tokens_count (state *s)
 | Compute LA, NLA, and the lookahead_tokens members.  |
 `----------------------------------------------------*/
 
 | Compute LA, NLA, and the lookahead_tokens members.  |
 `----------------------------------------------------*/
 

-static void
+void

 initialize_LA (void)
 {
   state_number i;
   bitsetv pLA;
 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;
   for (i = 0; i < nstates; i++)
 
   /* Compute the total number of reductions requiring a lookahead.  */
   nLA = 0;
   for (i = 0; i < nstates; i++)

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

-      int count = state_lookahead_tokens_count (states[i]);
+      int count =
+        state_lookahead_tokens_count (states[i],
+                                      default_reduction_only_for_accept);

       if (count)
       if (count)

-       {
-         states[i]->reductions->lookahead_tokens = pLA;
-         pLA += count;
-       }
+        {
+          states[i]->reductions->lookahead_tokens = pLA;
+          pLA += count;
+        }

     }
 }
 
     }
 }
 


@@ -419,21 +421,21 @@ lookahead_tokens_print (FILE *out)
       int n_lookahead_tokens = 0;
 
       if (reds->lookahead_tokens)
       int n_lookahead_tokens = 0;
 
       if (reds->lookahead_tokens)

-       for (k = 0; k < reds->num; ++k)
-         if (reds->lookahead_tokens[k])
-           ++n_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",
 
       fprintf (out, "State %d: %d lookahead tokens\n",

-              i, n_lookahead_tokens);
+               i, n_lookahead_tokens);

 
       if (reds->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);
-         };
+        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");
 }
     }
   fprintf (out, "Lookahead tokens: END\n");
 }


@@ -444,6 +446,7 @@ lalr (void)
   initialize_LA ();
   set_goto_map ();
   initialize_F ();
   initialize_LA ();
   set_goto_map ();
   initialize_F ();

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

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


@@ -453,6 +456,40 @@ lalr (void)
 }
 
 
 }
 
 

+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)
 {
 void
 lalr_free (void)
 {