* src/LR0.c (augment_automaton): Better variable locality.

[bison.git] / src / nullable.c

diff --git a/src/nullable.c b/src/nullable.c
index f931f4a99bf306a39790ad59937de23b0779dace..8e8809e20b993f6f865aade2202fefe4f5c5e6bf 100644 (file)
--- a/src/nullable.c
+++ b/src/nullable.c
@@ -1,138 +1,135 @@
 /* Part of the bison parser generator,
 /* Part of the bison parser generator,

-   Copyright (C) 1984, 1989 Free Software Foundation, Inc.
+   Copyright 1984, 1989, 2000, 2001 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
-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.
+   Bison is free software; you can redistribute it and/or modify
+   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.

 
 

-Bison 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.
+   Bison 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
-along with Bison; see the file COPYING.  If not, write to
-the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
+   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.  */

 
 
 
 

-/* set up nullable, a vector saying which nonterminals can expand into the null string.
-   nullable[i - ntokens] is nonzero if symbol i can do so.  */
+/* Set up NULLABLE, a vector saying which nonterminals can expand into
+   the null string.  NULLABLE[I - NTOKENS] is nonzero if symbol I can
+   do so.  */

 
 

-#include <stdio.h>

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

+#include "getargs.h"
+#include "reader.h"

 #include "types.h"
 #include "gram.h"
 #include "types.h"
 #include "gram.h"

-#include "alloc.h"
+#include "reduce.h"
+#include "nullable.h"

 
 

+char *nullable = NULL;

 
 

-char *nullable;
-
-void free_nullable PARAMS((void));
-void set_nullable PARAMS((void));
+static void
+nullable_print (FILE *out)
+{
+  int i;
+  fputs ("NULLABLE\n", out);
+  for (i = ntokens; i < nsyms; i++)
+    fprintf (out, "\t%s: %s\n", tags[i], nullable[i] ? "yes" : "no");
+  fputs ("\n\n", out);
+}

 
 void
 set_nullable (void)
 {
 
 void
 set_nullable (void)
 {

-  register short *r;
-  register short *s1;
-  register short *s2;
-  register int ruleno;
-  register int symbol;
-  register shorts *p;
+  short *r;
+  short *s1;
+  short *s2;
+  shorts *p;

 
   short *squeue;
   short *rcount;
   shorts **rsets;
   shorts *relts;
 
   short *squeue;
   short *rcount;
   shorts **rsets;
   shorts *relts;

-  char any_tokens;
-  short *r1;

 
 

-#ifdef TRACE
-  fprintf(stderr, _("Entering set_nullable"));
-#endif
+  if (trace_flag)
+    fprintf (stderr, "Entering set_nullable\n");

 
 

-  nullable = NEW2(nvars, char) - ntokens;
+  nullable = XCALLOC (char, nvars) - ntokens;

 
 

-  squeue = NEW2(nvars, short);
+  squeue = XCALLOC (short, nvars);

   s1 = s2 = squeue;
 
   s1 = s2 = squeue;
 

-  rcount = NEW2(nrules + 1, short);
-  rsets = NEW2(nvars, shorts *) - ntokens;
+  rcount = XCALLOC (short, nrules + 1);
+
+  /* RITEM contains all the rules, including useless productions.
+     Hence we must allocate room for useless nonterminals too.  */
+  rsets = XCALLOC (shorts *, nvars + nuseless_nonterminals) - ntokens;

   /* This is said to be more elements than we actually use.
      Supposedly nitems - nrules is enough.
      But why take the risk?  */
   /* This is said to be more elements than we actually use.
      Supposedly nitems - nrules is enough.
      But why take the risk?  */

-  relts = NEW2(nitems + nvars + 1, shorts);
+  relts = XCALLOC (shorts, nitems + nvars + nuseless_nonterminals + 1);

   p = relts;
 
   p = relts;
 

-  r = ritem;
-  while (*r)
+  for (r = ritem; *r; ++r)

     {
     {

-      if (*r < 0)
+      /* Walk RITEM to find (i), if there are any tokens in the
+        RHS, and (ii), to find RULENO. */
+      int ruleno;
+      int any_tokens = 0;
+      short *r1;
+      for (r1 = r; *r1 > 0; ++r1)
+       if (ISTOKEN (*r1))
+         any_tokens = 1;
+      ruleno = -*r1;
+
+      /* Examine the RHS of the rule.  */
+      if (!any_tokens)
+       for (/* Nothing. */; *r > 0; ++r)
+         {
+           rcount[ruleno]++;
+           p->next = rsets[*r];
+           p->value = ruleno;
+           rsets[*r] = p;
+           p++;
+         }
+
+      /* Examine its LHS. */
+      if (rule_table[ruleno].useful && !nullable[rule_table[ruleno].lhs])

        {
        {

-         symbol = rlhs[-(*r++)];
-         if (symbol >= 0 && !nullable[symbol])
-           {
-             nullable[symbol] = 1;
-             *s2++ = symbol;
-           }
-       }
-      else
-       {
-         r1 = r;
-         any_tokens = 0;
-         for (symbol = *r++; symbol > 0; symbol = *r++)
-           {
-             if (ISTOKEN(symbol))
-               any_tokens = 1;
-           }
-
-         if (!any_tokens)
-           {
-             ruleno = -symbol;
-             r = r1;
-             for (symbol = *r++; symbol > 0; symbol = *r++)
-               {
-                 rcount[ruleno]++;
-                 p->next = rsets[symbol];
-                 p->value = ruleno;
-                 rsets[symbol] = p;
-                 p++;
-               }
-           }
-       }
+         nullable[rule_table[ruleno].lhs] = 1;
+         *s2++ = rule_table[ruleno].lhs;
+        }

     }
 
   while (s1 < s2)
     }
 
   while (s1 < s2)

-    {
-      p = rsets[*s1++];
-      while (p)
-       {
-         ruleno = p->value;
-         p = p->next;
-         if (--rcount[ruleno] == 0)
+    for (p = rsets[*s1++]; p; p = p->next)
+      {
+       int ruleno = p->value;
+       if (--rcount[ruleno] == 0)
+         if (rule_table[ruleno].useful && !nullable[rule_table[ruleno].lhs])

            {
            {

-             symbol = rlhs[ruleno];
-             if (symbol >= 0 && !nullable[symbol])
-               {
-                 nullable[symbol] = 1;
-                 *s2++ = symbol;
-               }
+             nullable[rule_table[ruleno].lhs] = 1;
+             *s2++ = rule_table[ruleno].lhs;

            }
            }

-       }
-    }
+      }
+
+  XFREE (squeue);
+  XFREE (rcount);
+  XFREE (rsets + ntokens);
+  XFREE (relts);

 
 

-  FREE(squeue);
-  FREE(rcount);
-  FREE(rsets + ntokens);
-  FREE(relts);
+  if (trace_flag)
+    nullable_print (stderr);

 }
 
 
 void
 free_nullable (void)
 {
 }
 
 
 void
 free_nullable (void)
 {

-  FREE(nullable + ntokens);
+  XFREE (nullable + ntokens);

 }
 }