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[bison.git] / src / nullable.c

diff --git a/src/nullable.c b/src/nullable.c
index 1a96bef265b6fcf763285b28dd267b926859d63f..7ee661201ec4aeed6f3cb320ecd6aef6b09acd95 100644 (file)
--- a/src/nullable.c
+++ b/src/nullable.c
@@ -1,28 +1,29 @@
-/* Part of the bison parser generator,
-   Copyright (C) 1984, 1989, 2000, 2001, 2002 Free Software Foundation, Inc.
+/* Calculate which nonterminals can expand into the null string for Bison.
+
+   Copyright (C) 1984, 1989, 2000, 2001, 2002, 2003, 2004, 2005, 2006
+   Free Software Foundation, Inc.
 
    This file is part of Bison, the GNU Compiler Compiler.
 
-   Bison is free software; you can redistribute it and/or modify
+   This program 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.
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
 
-   Bison is distributed in the hope that it will be useful,
+   This program 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, Inc., 59 Temple Place - Suite 330,
-   Boston, MA 02111-1307, USA.  */
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
 
 /* 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 <config.h>
 #include "system.h"
 
 #include "getargs.h"
@@ -46,7 +47,8 @@ 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");
+    fprintf (out, "\t%s: %s\n", symbols[i]->tag,
+            nullable[i - ntokens] ? "yes" : "no");
   fputs ("\n\n", out);
 }
 
@@ -58,16 +60,16 @@ nullable_compute (void)
   symbol_number *s2;
   rule_list *p;
 
-  symbol_number *squeue = XCALLOC (symbol_number, nvars);
-  short *rcount = XCALLOC (short, nrules);
+  symbol_number *squeue = xnmalloc (nvars, sizeof *squeue);
+  size_t *rcount = xcalloc (nrules, sizeof *rcount);
   /* RITEM contains all the rules, including useless productions.
      Hence we must allocate room for useless nonterminals too.  */
-  rule_list **rsets = XCALLOC (rule_list *, nvars) - ntokens;
+  rule_list **rsets = xcalloc (nvars, sizeof *rsets);
   /* This is said to be more elements than we actually use.
      Supposedly NRITEMS - NRULES is enough.  But why take the risk?  */
-  rule_list *relts = XCALLOC (rule_list, nritems + nvars + 1);
+  rule_list *relts = xnmalloc (nritems + nvars + 1, sizeof *relts);
 
-  nullable = XCALLOC (bool, nvars) - ntokens;
+  nullable = xcalloc (nvars, sizeof *nullable);
 
   s1 = s2 = squeue;
   p = relts;
@@ -79,53 +81,54 @@ nullable_compute (void)
        if (rules_ruleno->rhs[0] >= 0)
          {
            /* This rule has a non empty RHS. */
-           item_number *r = NULL;
-           int any_tokens = 0;
-           for (r = rules_ruleno->rhs; *r >= 0; ++r)
-             if (ISTOKEN (*r))
-               any_tokens = 1;
+           item_number *rp = NULL;
+           bool any_tokens = false;
+           for (rp = rules_ruleno->rhs; *rp >= 0; ++rp)
+             if (ISTOKEN (*rp))
+               any_tokens = true;
 
            /* This rule has only nonterminals: schedule it for the second
               pass.  */
            if (!any_tokens)
-             for (r = rules_ruleno->rhs; *r >= 0; ++r)
+             for (rp = rules_ruleno->rhs; *rp >= 0; ++rp)
                {
                  rcount[ruleno]++;
-                 p->next = rsets[*r];
+                 p->next = rsets[*rp - ntokens];
                  p->value = rules_ruleno;
-                 rsets[*r] = p;
+                 rsets[*rp - ntokens] = p;
                  p++;
                }
          }
        else
          {
            /* This rule has an empty RHS. */
-           if (item_number_as_rule_number (rules_ruleno->rhs[0]) != ruleno)
-             abort ();
-           if (rules_ruleno->useful && !nullable[rules_ruleno->lhs->number])
+           aver (item_number_as_rule_number (rules_ruleno->rhs[0])
+                 == ruleno);
+           if (rules_ruleno->useful
+               && ! nullable[rules_ruleno->lhs->number - ntokens])
              {
-               nullable[rules_ruleno->lhs->number] = 1;
+               nullable[rules_ruleno->lhs->number - ntokens] = true;
                *s2++ = rules_ruleno->lhs->number;
              }
          }
       }
 
   while (s1 < s2)
-    for (p = rsets[*s1++]; p; p = p->next)
+    for (p = rsets[*s1++ - ntokens]; p; p = p->next)
       {
        rule *r = p->value;
        if (--rcount[r->number] == 0)
-         if (r->useful && !nullable[r->lhs->number])
+         if (r->useful && ! nullable[r->lhs->number - ntokens])
            {
-             nullable[r->lhs->number] = 1;
+             nullable[r->lhs->number - ntokens] = true;
              *s2++ = r->lhs->number;
            }
       }
 
-  XFREE (squeue);
-  XFREE (rcount);
-  XFREE (rsets + ntokens);
-  XFREE (relts);
+  free (squeue);
+  free (rcount);
+  free (rsets);
+  free (relts);
 
   if (trace_flag & trace_sets)
     nullable_print (stderr);
@@ -135,5 +138,5 @@ nullable_compute (void)
 void
 nullable_free (void)
 {
-  XFREE (nullable + ntokens);
+  free (nullable);
 }