* src/nullable.c (set_nullable): Deobfuscate the handling of

ritem.
`symbol >= 0' is wrong now, use `rule_table[ruleno].useful'.

ChangeLog

@@ -1,3 +1,10 @@
+2001-12-05  Akim Demaille  <akim@epita.fr>
+
+	* src/nullable.c (set_nullable): Deobfuscate the handling of
+	ritem.
+	`symbol >= 0' is wrong now, use `rule_table[ruleno].useful'.
+
+	
 2001-12-05  Akim Demaille  <akim@epita.fr>
 
 	* src/gram.c, src/gram.h (ritem_print): New.

src/nullable.c

@@ -71,40 +71,34 @@ set_nullable (void)
   relts = XCALLOC (shorts, nitems + nvars + 1);
   p = relts;
 
-  r = ritem;
+  for (r = ritem; *r; ++r)
-  while (*r)
-    {
-      if (*r < 0)
-	{
-	  int symbol = rule_table[-(*r++)].lhs;
-	  if (symbol >= 0 && !nullable[symbol])
-	    {
-	      nullable[symbol] = 1;
-	      *s2++ = symbol;
-	    }
-	}
-      else
     {
+      /* Walk RITEM to find (i), if there are any tokens in the
+	 RHS, and (ii), to find RULENO. */
+      int ruleno;
       int any_tokens = 0;
-	  int symbol;
+      short *r1;
-	  short *r1 = r;
+      for (r1 = r; *r1 > 0; ++r1)
-	  for (symbol = *r++; symbol > 0; symbol = *r++)
+	if (ISTOKEN (*r1))
-	    if (ISTOKEN (symbol))
 	  any_tokens = 1;
+      ruleno = -*r1;
 
+      /* Examine the RHS of the rule.  */
       if (!any_tokens)
-	    {
+	for (/* Nothing. */; *r > 0; ++r)
-	      int ruleno = -symbol;
-	      r = r1;
-	      for (symbol = *r++; symbol > 0; symbol = *r++)
 	  {
 	    rcount[ruleno]++;
-		  p->next = rsets[symbol];
+	    p->next = rsets[*r];
 	    p->value = ruleno;
-		  rsets[symbol] = p;
+	    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;
         }
     }