Regen.

[bison.git] / src / nullable.c

diff --git a/src/nullable.c b/src/nullable.c
index 8e8809e20b993f6f865aade2202fefe4f5c5e6bf..f8c9b32e5cf523b36742cb375ef0a087188ce2be 100644 (file)
--- a/src/nullable.c
+++ b/src/nullable.c
@@ -25,7 +25,7 @@
 
 #include "system.h"
 #include "getargs.h"
 
 #include "system.h"
 #include "getargs.h"

-#include "reader.h"
+#include "symtab.h"

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


@@ -39,82 +39,80 @@ nullable_print (FILE *out)
   int i;
   fputs ("NULLABLE\n", out);
   for (i = ntokens; i < nsyms; i++)
   int i;
   fputs ("NULLABLE\n", out);
   for (i = ntokens; i < nsyms; i++)

-    fprintf (out, "\t%s: %s\n", tags[i], nullable[i] ? "yes" : "no");
+    fprintf (out, "\t%s: %s\n", symbols[i]->tag, nullable[i] ? "yes" : "no");

   fputs ("\n\n", out);
 }
 
 void
 set_nullable (void)
 {
   fputs ("\n\n", out);
 }
 
 void
 set_nullable (void)
 {

-  short *r;
+  int ruleno;

   short *s1;
   short *s2;
   shorts *p;
 
   short *s1;
   short *s2;
   shorts *p;
 

-  short *squeue;
-  short *rcount;
-  shorts **rsets;
-  shorts *relts;
+  short *squeue = XCALLOC (short, nvars);
+  short *rcount = XCALLOC (short, nrules + 1);
+  /* RITEM contains all the rules, including useless productions.
+     Hence we must allocate room for useless nonterminals too.  */
+  shorts **rsets = XCALLOC (shorts *, nvars) - ntokens;
+  /* This is said to be more elements than we actually use.
+     Supposedly NRITEMS - NRULES is enough.  But why take the risk?  */
+  shorts *relts = XCALLOC (shorts, nritems + nvars + 1);

 
   if (trace_flag)
     fprintf (stderr, "Entering set_nullable\n");
 
   nullable = XCALLOC (char, nvars) - ntokens;
 
 
   if (trace_flag)
     fprintf (stderr, "Entering set_nullable\n");
 
   nullable = XCALLOC (char, nvars) - ntokens;
 

-  squeue = XCALLOC (short, nvars);

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

-
-  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?  */
-  relts = XCALLOC (shorts, nitems + nvars + nuseless_nonterminals + 1);

   p = relts;
 
   p = relts;
 

-  for (r = ritem; *r; ++r)
-    {
-      /* 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)
+  for (ruleno = 1; ruleno < nrules + 1; ++ruleno)
+    if (rules[ruleno].useful)
+      {
+       if (ritem[rules[ruleno].rhs] >= 0)

          {
          {

-           rcount[ruleno]++;
-           p->next = rsets[*r];
-           p->value = ruleno;
-           rsets[*r] = p;
-           p++;
+           /* This rule has a non empty RHS. */
+           short *r;
+           int any_tokens = 0;
+           for (r = &ritem[rules[ruleno].rhs]; *r >= 0; ++r)
+             if (ISTOKEN (*r))
+               any_tokens = 1;
+
+           /* This rule has only nonterminals: schedule it for the second
+              pass.  */
+           if (!any_tokens)
+             for (r = &ritem[rules[ruleno].rhs]; *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])
-       {
-         nullable[rule_table[ruleno].lhs] = 1;
-         *s2++ = rule_table[ruleno].lhs;
-        }
-    }
+       else
+         {
+           /* This rule has an empty RHS. */
+           assert (ritem[rules[ruleno].rhs] == -ruleno);
+           if (rules[ruleno].useful && !nullable[rules[ruleno].lhs])
+             {
+               nullable[rules[ruleno].lhs] = 1;
+               *s2++ = rules[ruleno].lhs;
+             }
+         }
+      }

 
   while (s1 < s2)
     for (p = rsets[*s1++]; p; p = p->next)
       {
 
   while (s1 < s2)
     for (p = rsets[*s1++]; p; p = p->next)
       {

-       int ruleno = p->value;
+       ruleno = p->value;

        if (--rcount[ruleno] == 0)
        if (--rcount[ruleno] == 0)

-         if (rule_table[ruleno].useful && !nullable[rule_table[ruleno].lhs])
+         if (rules[ruleno].useful && !nullable[rules[ruleno].lhs])

            {
            {

-             nullable[rule_table[ruleno].lhs] = 1;
-             *s2++ = rule_table[ruleno].lhs;
+             nullable[rules[ruleno].lhs] = 1;
+             *s2++ = rules[ruleno].lhs;

            }
       }
 
            }
       }