119 lines
2.2 KiB
C
119 lines
2.2 KiB
C
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/* Match rules with nonterminals for bison,
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Copyright (C) 1984, 1989 Free Software Foundation, Inc.
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This file is part of Bison, the GNU Compiler Compiler.
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Bison is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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Bison is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with Bison; see the file COPYING. If not, write to
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the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
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/* set_derives finds, for each variable (nonterminal), which rules can derive it.
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It sets up the value of derives so that
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derives[i - ntokens] points to a vector of rule numbers,
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terminated with -1. */
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#include <stdio.h>
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#include "system.h"
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#include "new.h"
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#include "types.h"
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#include "gram.h"
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short **derives;
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void
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set_derives()
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{
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register int i;
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register int lhs;
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register shorts *p;
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register short *q;
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register shorts **dset;
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register shorts *delts;
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dset = NEW2(nvars, shorts *) - ntokens;
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delts = NEW2(nrules + 1, shorts);
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p = delts;
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for (i = nrules; i > 0; i--)
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{
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lhs = rlhs[i];
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if (lhs >= 0)
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{
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p->next = dset[lhs];
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p->value = i;
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dset[lhs] = p;
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p++;
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}
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}
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derives = NEW2(nvars, short *) - ntokens;
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q = NEW2(nvars + nrules, short);
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for (i = ntokens; i < nsyms; i++)
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{
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derives[i] = q;
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p = dset[i];
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while (p)
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{
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*q++ = p->value;
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p = p->next;
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}
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*q++ = -1;
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}
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#ifdef DEBUG
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print_derives();
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#endif
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FREE(dset + ntokens);
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FREE(delts);
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}
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void
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free_derives()
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{
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FREE(derives[ntokens]);
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FREE(derives + ntokens);
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}
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#ifdef DEBUG
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print_derives()
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{
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register int i;
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register short *sp;
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extern char **tags;
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printf("\n\n\nDERIVES\n\n");
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for (i = ntokens; i < nsyms; i++)
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{
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printf("%s derives", tags[i]);
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for (sp = derives[i]; *sp > 0; sp++)
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{
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printf(" %d", *sp);
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}
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putchar('\n');
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}
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putchar('\n');
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}
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#endif
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