Stop storing rules from 1 to nrules + 1.

[bison.git] / src / nullable.c

diff --git a/src/nullable.c b/src/nullable.c
index 7240132f526e04914b81d359c23252211d3a7032..6a70fa572be96a66dd3aa90c4b8dc6374234408f 100644 (file)
--- a/src/nullable.c
+++ b/src/nullable.c
@@ -1,5 +1,5 @@
 /* Part of the bison parser generator,
 /* Part of the bison parser generator,

-   Copyright 1984, 1989, 2000 Free Software Foundation, Inc.
+   Copyright (C) 1984, 1989, 2000, 2001, 2002 Free Software Foundation, Inc.

 
    This file is part of Bison, the GNU Compiler Compiler.
 
 
    This file is part of Bison, the GNU Compiler Compiler.
 


@@ -24,108 +24,112 @@
    do so.  */
 
 #include "system.h"
    do so.  */
 
 #include "system.h"

-#include "types.h"
+#include "getargs.h"
+#include "symtab.h"

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

-#include "xalloc.h"
+#include "reduce.h"

 #include "nullable.h"
 
 #include "nullable.h"
 

+/* Linked list of rule numbers.  */
+typedef struct rule_list_s
+{
+  struct rule_list_s *next;
+  rule_number_t value;
+} rule_list_t;
+

 char *nullable = NULL;
 
 char *nullable = NULL;
 

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

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

-  short *r;
-  short *s1;
-  short *s2;
-  int ruleno;
-  int symbol;
-  shorts *p;
-
-  short *squeue;
-  short *rcount;
-  shorts **rsets;
-  shorts *relts;
-  char any_tokens;
-  short *r1;
-
-#ifdef TRACE
-  fprintf (stderr, _("Entering set_nullable"));
-#endif
+  rule_number_t ruleno;
+  symbol_number_t *s1;
+  symbol_number_t *s2;
+  rule_list_t *p;
+
+  symbol_number_t *squeue = XCALLOC (symbol_number_t, nvars);
+  short *rcount = XCALLOC (short, nrules);
+  /* RITEM contains all the rules, including useless productions.
+     Hence we must allocate room for useless nonterminals too.  */
+  rule_list_t **rsets = XCALLOC (rule_list_t *, nvars) - ntokens;
+  /* This is said to be more elements than we actually use.
+     Supposedly NRITEMS - NRULES is enough.  But why take the risk?  */
+  rule_list_t *relts = XCALLOC (rule_list_t, nritems + nvars + 1);
+
+  if (trace_flag)
+    fprintf (stderr, "Entering set_nullable\n");

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

-  squeue = XCALLOC (short, nvars);

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

-
-  rcount = XCALLOC (short, nrules + 1);
-  rsets = XCALLOC (shorts *, nvars) - 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 + 1);

   p = relts;
 
   p = relts;
 

-  r = ritem;
-  while (*r)
-    {
-      if (*r < 0)
-       {
-         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))
+  for (ruleno = 0; ruleno < nrules; ++ruleno)
+    if (rules[ruleno].useful)
+      {
+       rule_t *rule = &rules[ruleno];
+       if (rule->rhs[0] >= 0)
+         {
+           /* This rule has a non empty RHS. */
+           item_number_t *r = NULL;
+           int any_tokens = 0;
+           for (r = rule->rhs; *r >= 0; ++r)
+             if (ISTOKEN (*r))

                any_tokens = 1;
                any_tokens = 1;

-           }

 
 

-         if (!any_tokens)
-           {
-             ruleno = -symbol;
-             r = r1;
-             for (symbol = *r++; symbol > 0; symbol = *r++)
+           /* This rule has only nonterminals: schedule it for the second
+              pass.  */
+           if (!any_tokens)
+             for (r = rule->rhs; *r >= 0; ++r)

                {
                  rcount[ruleno]++;
                {
                  rcount[ruleno]++;

-                 p->next = rsets[symbol];
+                 p->next = rsets[*r];

                  p->value = ruleno;
                  p->value = ruleno;

-                 rsets[symbol] = p;
+                 rsets[*r] = p;

                  p++;
                }
                  p++;
                }

-           }
-       }
-    }
+         }
+       else
+         {
+           /* This rule has an empty RHS. */
+           assert (item_number_as_rule_number (rule->rhs[0]) == ruleno);
+           if (rule->useful && !nullable[rule->lhs->number])
+             {
+               nullable[rule->lhs->number] = 1;
+               *s2++ = rule->lhs->number;
+             }
+         }
+      }

 
   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)
+      {
+       ruleno = p->value;
+       if (--rcount[ruleno] == 0)
+         if (rules[ruleno].useful && !nullable[rules[ruleno].lhs->number])

            {
            {

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

            }
            }

-       }
-    }
+      }

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

+
+  if (trace_flag)
+    nullable_print (stderr);

 }
 
 
 }