/*      $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));
}