Add native Windows binary for bison.

bison/src/bison/2.4.1/bison-2.4.1-src/src/nullable.c

+/* 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.
+
+   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 3 of the License, or
+   (at your option) any later version.
+
+   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 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"
+#include "gram.h"
+#include "nullable.h"
+#include "reduce.h"
+#include "symtab.h"
+
+/* Linked list of rules.  */
+typedef struct rule_list
+{
+  struct rule_list *next;
+  rule *value;
+} rule_list;
+
+bool *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 - ntokens] ? "yes" : "no");
+  fputs ("\n\n", out);
+}
+
+void
+nullable_compute (void)
+{
+  rule_number ruleno;
+  symbol_number *s1;
+  symbol_number *s2;
+  rule_list *p;
+
+  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 (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 = xnmalloc (nritems + nvars + 1, sizeof *relts);
+
+  nullable = xcalloc (nvars, sizeof *nullable);
+
+  s1 = s2 = squeue;
+  p = relts;
+
+  for (ruleno = 0; ruleno < nrules; ++ruleno)
+    if (rules[ruleno].useful)
+      {
+        rule *rules_ruleno = &rules[ruleno];
+        if (rules_ruleno->rhs[0] >= 0)
+          {
+            /* This rule has a non empty RHS. */
+            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 (rp = rules_ruleno->rhs; *rp >= 0; ++rp)
+                {
+                  rcount[ruleno]++;
+                  p->next = rsets[*rp - ntokens];
+                  p->value = rules_ruleno;
+                  rsets[*rp - ntokens] = p;
+                  p++;
+                }
+          }
+        else
+          {
+            /* This rule has an empty RHS. */
+            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 - ntokens] = true;
+                *s2++ = rules_ruleno->lhs->number;
+              }
+          }
+      }
+
+  while (s1 < s2)
+    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 - ntokens])
+            {
+              nullable[r->lhs->number - ntokens] = true;
+              *s2++ = r->lhs->number;
+            }
+      }
+
+  free (squeue);
+  free (rcount);
+  free (rsets);
+  free (relts);
+
+  if (trace_flag & trace_sets)
+    nullable_print (stderr);
+}
+
+
+void
+nullable_free (void)
+{
+  free (nullable);
+}