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/* Match rules with nonterminals for bison,
Copyright (C) 1984, 1989 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
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.
Bison 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, 675 Mass Ave, Cambridge, MA 02139, USA. */
/* set_derives finds, for each variable (nonterminal), which rules can derive it.
It sets up the value of derives so that
derives[i - ntokens] points to a vector of rule numbers,
terminated with -1. */
#include <stdio.h>
#include "system.h"
#include "new.h"
#include "types.h"
#include "gram.h"
short **derives;
void
set_derives()
{
register int i;
register int lhs;
register shorts *p;
register short *q;
register shorts **dset;
register shorts *delts;
dset = NEW2(nvars, shorts *) - ntokens;
delts = NEW2(nrules + 1, shorts);
p = delts;
for (i = nrules; i > 0; i--)
{
lhs = rlhs[i];
if (lhs >= 0)
{
p->next = dset[lhs];
p->value = i;
dset[lhs] = p;
p++;
}
}
derives = NEW2(nvars, short *) - ntokens;
q = NEW2(nvars + nrules, short);
for (i = ntokens; i < nsyms; i++)
{
derives[i] = q;
p = dset[i];
while (p)
{
*q++ = p->value;
p = p->next;
}
*q++ = -1;
}
#ifdef DEBUG
print_derives();
#endif
FREE(dset + ntokens);
FREE(delts);
}
void
free_derives()
{
FREE(derives[ntokens]);
FREE(derives + ntokens);
}
#ifdef DEBUG
print_derives()
{
register int i;
register short *sp;
extern char **tags;
printf("\n\n\nDERIVES\n\n");
for (i = ntokens; i < nsyms; i++)
{
printf("%s derives", tags[i]);
for (sp = derives[i]; *sp > 0; sp++)
{
printf(" %d", *sp);
}
putchar('\n');
}
putchar('\n');
}
#endif
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