src/derives.c

/* Match rules with nonterminals for bison,
   Copyright 1984, 1989, 2000 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, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, 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 "system.h"
#include "xalloc.h"
#include "types.h"
#include "gram.h"
#include "derives.h"

short **derives;

#if DEBUG

static void
print_derives (void)
{
  int i;
  short *sp;

  fputs ("\n\n\n", stdout);
  printf (_("DERIVES"));
  fputs ("\n\n", stdout);

  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

void
set_derives (void)
{
  int i;
  int lhs;
  shorts *p;
  short *q;
  shorts **dset;
  shorts *delts;

  dset = XCALLOC (shorts *, nvars) - ntokens;
  delts = XCALLOC (shorts, nrules + 1);

  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 = XCALLOC (short *, nvars) - ntokens;
  q = XCALLOC (short, nvars + nrules);

  for (i = ntokens; i < nsyms; i++)
    {
      derives[i] = q;
      p = dset[i];
      while (p)
	{
	  *q++ = p->value;
	  p = p->next;
	}
      *q++ = -1;
    }

#if DEBUG
  print_derives ();
#endif

  XFREE (dset + ntokens);
  XFREE (delts);
}

void
free_derives (void)
{
  XFREE (derives[ntokens]);
  XFREE (derives + ntokens);
}
Commit	Line	Data
	1	/* Match rules with nonterminals for bison,
	2	Copyright 1984, 1989, 2000 Free Software Foundation, Inc.
	3
	4	This file is part of Bison, the GNU Compiler Compiler.
	5
	6	Bison is free software; you can redistribute it and/or modify
	7	it under the terms of the GNU General Public License as published by
	8	the Free Software Foundation; either version 2, or (at your option)
	9	any later version.
	10
	11	Bison is distributed in the hope that it will be useful,
	12	but WITHOUT ANY WARRANTY; without even the implied warranty of
	13	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	14	GNU General Public License for more details.
	15
	16	You should have received a copy of the GNU General Public License
	17	along with Bison; see the file COPYING. If not, write to
	18	the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
	19	Boston, MA 02111-1307, USA. */
	20
	21
	22	/* set_derives finds, for each variable (nonterminal), which rules can
	23	derive it. It sets up the value of derives so that derives[i -
	24	ntokens] points to a vector of rule numbers, terminated with -1.
	25	*/
	26
	27	#include "system.h"
	28	#include "xalloc.h"
	29	#include "types.h"
	30	#include "gram.h"
	31	#include "derives.h"
	32
	33	short **derives;
	34
	35	#if DEBUG
	36
	37	static void
	38	print_derives (void)
	39	{
	40	int i;
	41	short *sp;
	42
	43	fputs ("\n\n\n", stdout);
	44	printf (_("DERIVES"));
	45	fputs ("\n\n", stdout);
	46
	47	for (i = ntokens; i < nsyms; i++)
	48	{
	49	printf (_("%s derives"), tags[i]);
	50	for (sp = derives[i]; *sp > 0; sp++)
	51	{
	52	printf (" %d", *sp);
	53	}
	54	putchar ('\n');
	55	}
	56
	57	putchar ('\n');
	58	}
	59
	60	#endif
	61
	62	void
	63	set_derives (void)
	64	{
	65	int i;
	66	int lhs;
	67	shorts *p;
	68	short *q;
	69	shorts **dset;
	70	shorts *delts;
	71
	72	dset = XCALLOC (shorts *, nvars) - ntokens;
	73	delts = XCALLOC (shorts, nrules + 1);
	74
	75	p = delts;
	76	for (i = nrules; i > 0; i--)
	77	{
	78	lhs = rlhs[i];
	79	if (lhs >= 0)
	80	{
	81	p->next = dset[lhs];
	82	p->value = i;
	83	dset[lhs] = p;
	84	p++;
	85	}
	86	}
	87
	88	derives = XCALLOC (short *, nvars) - ntokens;
	89	q = XCALLOC (short, nvars + nrules);
	90
	91	for (i = ntokens; i < nsyms; i++)
	92	{
	93	derives[i] = q;
	94	p = dset[i];
	95	while (p)
	96	{
	97	*q++ = p->value;
	98	p = p->next;
	99	}
	100	*q++ = -1;
	101	}
	102
	103	#if DEBUG
	104	print_derives ();
	105	#endif
	106
	107	XFREE (dset + ntokens);
	108	XFREE (delts);
	109	}
	110
	111	void
	112	free_derives (void)
	113	{
	114	XFREE (derives[ntokens]);
	115	XFREE (derives + ntokens);
	116	}