xref: /openbsd/usr.bin/yacc/closure.c (revision 54b00945)

/*	$OpenBSD: closure.c,v 1.15 2017/05/25 20:11:03 tedu 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.
 */

#include "defs.h"

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

static unsigned *first_derives;
static unsigned *EFF;


#ifdef	DEBUG

static void
print_closure(int n)
{
	short *isp;

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

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

	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]);
		}
	}
}

static void
print_first_derives(void)
{
	int i, j;
	unsigned int *rp;
	unsigned int k, cword = 0;

	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


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

	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 int *rrow, *vrow;
	unsigned int k, cword = 0;
	int i, j, rule, rulesetsize, varsetsize;
	short *rp;

	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);
				}
			}
		}
		rrow += rulesetsize;
	}

#ifdef	DEBUG
	print_first_derives();
#endif

	free(EFF);
}


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

	rulesetsize = WORDSIZE(nrules);
	rsend = ruleset + rulesetsize;
	memset(ruleset, 0, rulesetsize * sizeof(*ruleset));

	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));
}