/* 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.
+ Copyright (C) 1984, 1989, 2000-2006, 2009-2012 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., 51 Franklin Street, Fifth Floor,
- Boston, MA 02110-1301, USA. */
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
/* Set up NULLABLE, a vector saying which nonterminals can expand into
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");
+ fprintf (out, " %s: %s\n", symbols[i]->tag,
+ nullable[i - ntokens] ? "yes" : "no");
fputs ("\n\n", out);
}
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. */
- assert (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;
- }
- }
+ 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;
- }
+ 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);