X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/e3e4e81446edb4e92e21cde1fc873f517b9402ea..e9f87b5b7df2e328d2e4196d276c0d96594c906b:/src/nullable.c

diff --git a/src/nullable.c b/src/nullable.c
index 8e8809e2..f8c9b32e 100644
--- a/src/nullable.c
+++ b/src/nullable.c
@@ -25,7 +25,7 @@
 
 #include "system.h"
 #include "getargs.h"
-#include "reader.h"
+#include "symtab.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++)
-    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)
 {
-  short *r;
+  int ruleno;
   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;
 
-  squeue = XCALLOC (short, nvars);
   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;
 
-  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)
       {
-	int ruleno = p->value;
+	ruleno = p->value;
 	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;
 	    }
       }