source: trunk/minix/commands/byacc/closure.c@ 20

#include "defs.h"

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

static unsigned *first_derives;
static unsigned *EFF;


set_EFF()
{
    register unsigned *row;
    register int symbol;
    register short *sp;
    register int rowsize;
    register int i;
    register 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
}


set_first_derives()
{
    register unsigned *rrow;
    register unsigned *vrow;
    register int j;
    register unsigned k;
    register unsigned cword;
    register 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);
}


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



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


#ifdef  DEBUG

print_closure(n)
int n;
{
  register short *isp;

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


print_EFF()
{
    register int i, j;
    register unsigned *rowp;
    register unsigned word;
    register 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]);
        }
    }
}


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