xref: /openbsd/usr.bin/yacc/closure.c (revision d1e49392)

/*	$OpenBSD: closure.c,v 1.7 2003/06/19 16:34:53 pvalchev Exp $	*/
/*	$NetBSD: closure.c,v 1.4 1996/03/19 03:21:29 jtc Exp $	*/

/*
 * Copyright (c) 1989 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Robert Paul Corbett.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#ifndef lint
#if 0
static char sccsid[] = "@(#)closure.c	5.3 (Berkeley) 5/24/93";
#else
static char rcsid[] = "$OpenBSD: closure.c,v 1.7 2003/06/19 16:34:53 pvalchev Exp $";
#endif
#endif /* not lint */

#include "defs.h"

short *itemset;
short *itemsetend;
unsigned *ruleset;

static unsigned *first_derives;
static unsigned *EFF;


void
set_EFF(void)
{
    unsigned *row;
    int symbol;
    short *sp;
    int rowsize;
    int i;
    int rule;

    rowsize = WORDSIZE(nvars);
    EFF = NEW2(nvars * rowsize, unsigned);

    row = EFF;
    for (i = start_symbol; i < nsyms; i++)
    {
	sp = derives[i];
	for (rule = *sp; rule > 0; rule = *++sp)
	{
	    symbol = ritem[rrhs[rule]];
	    if (ISVAR(symbol))
	    {
		symbol -= start_symbol;
		SETBIT(row, symbol);
	    }
	}
	row += rowsize;
    }

    reflexive_transitive_closure(EFF, nvars);

#ifdef	DEBUG
    print_EFF();
#endif
}


void
set_first_derives(void)
{
    unsigned *rrow;
    unsigned *vrow;
    int j;
    unsigned k;
    unsigned cword;
    short *rp;

    int rule;
    int i;
    int rulesetsize;
    int varsetsize;

    rulesetsize = WORDSIZE(nrules);
    varsetsize = WORDSIZE(nvars);
    first_derives = NEW2(nvars * rulesetsize, unsigned) - ntokens * rulesetsize;

    set_EFF();

    rrow = first_derives + ntokens * rulesetsize;
    for (i = start_symbol; i < nsyms; i++)
    {
	vrow = EFF + ((i - ntokens) * varsetsize);
	k = BITS_PER_WORD;
	for (j = start_symbol; j < nsyms; k++, j++)
	{
	    if (k >= BITS_PER_WORD)
	    {
		cword = *vrow++;
		k = 0;
	    }

	    if (cword & (1 << k))
	    {
		rp = derives[j];
		while ((rule = *rp++) >= 0)
		{
		    SETBIT(rrow, rule);
		}
	    }
	}

	vrow += varsetsize;
	rrow += rulesetsize;
    }

#ifdef	DEBUG
    print_first_derives();
#endif

    FREE(EFF);
}


void
closure(short *nucleus, int n)
{
    int ruleno;
    unsigned word;
    unsigned i;
    short *csp;
    unsigned *dsp;
    unsigned *rsp;
    int rulesetsize;

    short *csend;
    unsigned *rsend;
    int symbol;
    int itemno;

    rulesetsize = WORDSIZE(nrules);
    rsp = ruleset;
    rsend = ruleset + rulesetsize;
    for (rsp = ruleset; rsp < rsend; rsp++)
	*rsp = 0;

    csend = nucleus + n;
    for (csp = nucleus; csp < csend; ++csp)
    {
	symbol = ritem[*csp];
	if (ISVAR(symbol))
	{
	    dsp = first_derives + symbol * rulesetsize;
	    rsp = ruleset;
	    while (rsp < rsend)
		*rsp++ |= *dsp++;
	}
    }

    ruleno = 0;
    itemsetend = itemset;
    csp = nucleus;
    for (rsp = ruleset; rsp < rsend; ++rsp)
    {
	word = *rsp;
	if (word)
	{
	    for (i = 0; i < BITS_PER_WORD; ++i)
	    {
		if (word & (1 << i))
		{
		    itemno = rrhs[ruleno+i];
		    while (csp < csend && *csp < itemno)
			*itemsetend++ = *csp++;
		    *itemsetend++ = itemno;
		    while (csp < csend && *csp == itemno)
			++csp;
		}
	    }
	}
	ruleno += BITS_PER_WORD;
    }

    while (csp < csend)
	*itemsetend++ = *csp++;

#ifdef	DEBUG
  print_closure(n);
#endif
}



void
finalize_closure(void)
{
  FREE(itemset);
  FREE(ruleset);
  FREE(first_derives + ntokens * WORDSIZE(nrules));
}


#ifdef	DEBUG

void
print_closure(int n)
{
  short *isp;

  printf("\n\nn = %d\n\n", n);
  for (isp = itemset; isp < itemsetend; isp++)
    printf("   %d\n", *isp);
}

void
print_EFF(void)
{
    int i, j;
    unsigned *rowp;
    unsigned word;
    unsigned k;

    printf("\n\nEpsilon Free Firsts\n");

    for (i = start_symbol; i < nsyms; i++)
    {
	printf("\n%s", symbol_name[i]);
	rowp = EFF + ((i - start_symbol) * WORDSIZE(nvars));
	word = *rowp++;

	k = BITS_PER_WORD;
	for (j = 0; j < nvars; k++, j++)
	{
	    if (k >= BITS_PER_WORD)
	    {
		word = *rowp++;
		k = 0;
	    }

	    if (word & (1 << k))
		printf("  %s", symbol_name[start_symbol + j]);
	}
    }
}

void
print_first_derives(void)
{
    int i;
    int j;
    unsigned *rp;
    unsigned cword;
    unsigned k;

    printf("\n\n\nFirst Derives\n");

    for (i = start_symbol; i < nsyms; i++)
    {
	printf("\n%s derives\n", symbol_name[i]);
	rp = first_derives + i * WORDSIZE(nrules);
	k = BITS_PER_WORD;
	for (j = 0; j <= nrules; k++, j++)
        {
	  if (k >= BITS_PER_WORD)
	  {
	      cword = *rp++;
	      k = 0;
	  }

	  if (cword & (1 << k))
	    printf("   %d\n", j);
	}
    }

  fflush(stdout);
}

#endif