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Unified Diff: bison/src/bison/2.4.1/bison-2.4.1-src/src/nullable.c

Issue 10807020: Add native Windows binary for bison. (Closed) Base URL: svn://chrome-svn/chrome/trunk/deps/third_party/
Patch Set: Created 8 years, 5 months ago
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Index: bison/src/bison/2.4.1/bison-2.4.1-src/src/nullable.c
===================================================================
--- bison/src/bison/2.4.1/bison-2.4.1-src/src/nullable.c (revision 0)
+++ bison/src/bison/2.4.1/bison-2.4.1-src/src/nullable.c (revision 0)
@@ -0,0 +1,142 @@
+/* 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);
+}
Property changes on: bison\src\bison\2.4.1\bison-2.4.1-src\src\nullable.c
___________________________________________________________________
Added: svn:eol-style
+ LF
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