Power-Programmierung/CD2.mdf/c/compcomp/byacc/lr0.c

C/C++ Source or Header | 1990-12-15 | 10.0 KB | 605 lines

#include "defs.h"

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

int nstates;
core *first_state;
shifts *first_shift;
reductions *first_reduction;

int get_state();
core *new_state();

static core **state_set;
static core *this_state;
static core *last_state;
static shifts *last_shift;
static reductions *last_reduction;

static int nshifts;
static short *shift_symbol;

static short *redset;
static short *shiftset;

static short **kernel_base;
static short **kernel_end;
static short *kernel_items;


allocate_itemsets()
{
  register short *itemp;
  register short *item_end;
  register int symbol;
  register int i;
  register int count;
  register int max;
  register short *symbol_count;

  count = 0;
  symbol_count = NEW2(nsyms, short);

  item_end = ritem + nitems;
  for (itemp = ritem; itemp < item_end; itemp++)
    {
      symbol = *itemp;
      if (symbol >= 0)
    {
      count++;
      symbol_count[symbol]++;
    }
    }

  kernel_base = NEW2(nsyms, short *);
  kernel_items = NEW2(count, short);

  count = 0;
  max = 0;
  for (i = 0; i < nsyms; i++)
    {
      kernel_base[i] = kernel_items + count;
      count += symbol_count[i];
      if (max < symbol_count[i])
    max = symbol_count[i];
    }

  shift_symbol = symbol_count;
  kernel_end = NEW2(nsyms, short *);
}



allocate_storage()
{
  allocate_itemsets();

  shiftset = NEW2(nsyms, short);
  redset = NEW2(nrules + 1, short);
  state_set = NEW2(nitems, core *);
}



append_states()
{
  register int i;
  register int j;
  register int symbol;

#ifdef    TRACE
  fprintf(stderr, "Entering append_states\n");
#endif

  for (i = 1; i < nshifts; i++)
    {
      symbol = shift_symbol[i];
      j = i;
      while (j > 0 && shift_symbol[j - 1] > symbol)
    {
      shift_symbol[j] = shift_symbol[j - 1];
      j--;
    }
      shift_symbol[j] = symbol;
    }

  for (i = 0; i < nshifts; i++)
    {
      symbol = shift_symbol[i];
      shiftset[i] = get_state(symbol);
    }
}


free_storage()
{
  FREE(shift_symbol);
  FREE(redset);
  FREE(shiftset);
  FREE(kernel_base);
  FREE(kernel_end);
  FREE(kernel_items);
  FREE(state_set);
}



generate_states()
{
  allocate_storage();
  itemset = NEW2(nitems, short);
  ruleset = NEW2(WORDSIZE(nrules), unsigned);
  set_first_derives();
  initialize_states();

  while (this_state)
    {
      closure(this_state->items, this_state->nitems);
      save_reductions();
      new_itemsets();
      append_states();

      if (nshifts > 0)
        save_shifts();

      this_state = this_state->next;
    }

  finalize_closure();
  free_storage();
}



int
get_state(symbol)
int symbol;
{
  register int key;
  register short *isp1;
  register short *isp2;
  register short *iend;
  register core *sp;
  register int found;

  int n;

#ifdef    TRACE
  fprintf(stderr, "Entering get_state, symbol = %d\n", symbol);
#endif

  isp1 = kernel_base[symbol];
  iend = kernel_end[symbol];
  n = iend - isp1;

  key = *isp1;
  assert(0 <= key && key < nitems);
  sp = state_set[key];
  if (sp)
    {
      found = 0;
      while (!found)
    {
      if (sp->nitems == n)
        {
          found = 1;
          isp1 = kernel_base[symbol];
          isp2 = sp->items;

          while (found && isp1 < iend)
        {
          if (*isp1++ != *isp2++)
            found = 0;
        }
        }

      if (!found)
        {
          if (sp->link)
        {
          sp = sp->link;
        }
          else
        {
          sp = sp->link = new_state(symbol);
          found = 1;
        }
        }
    }
    }
  else
    {
      state_set[key] = sp = new_state(symbol);
    }

  return (sp->number);
}



initialize_states()
{
    register int i;
    register short *start_derives;
    register core *p;

    start_derives = derives[start_symbol];
    for (i = 0; start_derives[i] >= 0; ++i)
    continue;

    p = (core *) MALLOC(sizeof(core) + i*sizeof(short));
    if (p == 0) no_space();

    p->next = 0;
    p->link = 0;
    p->number = 0;
    p->accessing_symbol = 0;
    p->nitems = i;

    for (i = 0;  start_derives[i] >= 0; ++i)
    p->items[i] = rrhs[start_derives[i]];

    first_state = last_state = this_state = p;
    nstates = 1;
}


new_itemsets()
{
  register int i;
  register int shiftcount;
  register short *isp;
  register short *ksp;
  register int symbol;

  for (i = 0; i < nsyms; i++)
    kernel_end[i] = 0;

  shiftcount = 0;
  isp = itemset;
  while (isp < itemsetend)
    {
      i = *isp++;
      symbol = ritem[i];
      if (symbol > 0)
    {
          ksp = kernel_end[symbol];

          if (!ksp)
        {
          shift_symbol[shiftcount++] = symbol;
          ksp = kernel_base[symbol];
        }

          *ksp++ = i + 1;
          kernel_end[symbol] = ksp;
    }
    }

  nshifts = shiftcount;
}



core *
new_state(symbol)
int symbol;
{
  register int n;
  register core *p;
  register short *isp1;
  register short *isp2;
  register short *iend;

#ifdef    TRACE
  fprintf(stderr, "Entering new_state, symbol = %d\n", symbol);
#endif

  if (nstates >= MAXSHORT)
    fatal("too many states");

  isp1 = kernel_base[symbol];
  iend = kernel_end[symbol];
  n = iend - isp1;

  p = (core *) allocate((unsigned) (sizeof(core) + (n - 1) * sizeof(short)));
  p->accessing_symbol = symbol;
  p->number = nstates;
  p->nitems = n;

  isp2 = p->items;
  while (isp1 < iend)
    *isp2++ = *isp1++;

  last_state->next = p;
  last_state = p;

  nstates++;

  return (p);
}


/* show_cores is used for debugging */

show_cores()
{
    core *p;
    int i, j, k, n;
    int itemno;

    k = 0;
    for (p = first_state; p; ++k, p = p->next)
    {
    if (k) printf("\n");
    printf("state %d, number = %d, accessing symbol = %s\n",
        k, p->number, symbol_name[p->accessing_symbol]);
    n = p->nitems;
    for (i = 0; i < n; ++i)
    {
        itemno = p->items[i];
        printf("%4d  ", itemno);
        j = itemno;
        while (ritem[j] >= 0) ++j;
        printf("%s :", symbol_name[rlhs[-ritem[j]]]);
        j = rrhs[-ritem[j]];
        while (j < itemno)
        printf(" %s", symbol_name[ritem[j++]]);
        printf(" .");
        while (ritem[j] >= 0)
        printf(" %s", symbol_name[ritem[j++]]);
        printf("\n");
        fflush(stdout);
    }
    }
}


/* show_ritems is used for debugging */

show_ritems()
{
    int i;

    for (i = 0; i < nitems; ++i)
    printf("ritem[%d] = %d\n", i, ritem[i]);
}


/* show_rrhs is used for debugging */
show_rrhs()
{
    int i;

    for (i = 0; i < nrules; ++i)
    printf("rrhs[%d] = %d\n", i, rrhs[i]);
}


/* show_shifts is used for debugging */

show_shifts()
{
    shifts *p;
    int i, j, k;

    k = 0;
    for (p = first_shift; p; ++k, p = p->next)
    {
    if (k) printf("\n");
    printf("shift %d, number = %d, nshifts = %d\n", k, p->number,
        p->nshifts);
    j = p->nshifts;
    for (i = 0; i < j; ++i)
        printf("\t%d\n", p->shift[i]);
    }
}


save_shifts()
{
  register shifts *p;
  register short *sp1;
  register short *sp2;
  register short *send;

  p = (shifts *) allocate((unsigned) (sizeof(shifts) +
            (nshifts - 1) * sizeof(short)));

  p->number = this_state->number;
  p->nshifts = nshifts;

  sp1 = shiftset;
  sp2 = p->shift;
  send = shiftset + nshifts;

  while (sp1 < send)
    *sp2++ = *sp1++;

  if (last_shift)
    {
      last_shift->next = p;
      last_shift = p;
    }
  else
    {
      first_shift = p;
      last_shift = p;
    }
}



save_reductions()
{
  register short *isp;
  register short *rp1;
  register short *rp2;
  register int item;
  register int count;
  register reductions *p;

  short *rend;

  count = 0;
  for (isp = itemset; isp < itemsetend; isp++)
    {
      item = ritem[*isp];
      if (item < 0)
    {
      redset[count++] = -item;
    }
    }

  if (count)
    {
      p = (reductions *) allocate((unsigned) (sizeof(reductions) +
                    (count - 1) * sizeof(short)));

      p->number = this_state->number;
      p->nreds = count;

      rp1 = redset;
      rp2 = p->rules;
      rend = rp1 + count;

      while (rp1 < rend)
    *rp2++ = *rp1++;

      if (last_reduction)
    {
      last_reduction->next = p;
      last_reduction = p;
    }
      else
    {
      first_reduction = p;
      last_reduction = p;
    }
    }
}


set_derives()
{
  register int i, k;
  register int lhs;
  register short *rules;

  derives = NEW2(nsyms, short *);
  rules = NEW2(nvars + nrules, short);

  k = 0;
  for (lhs = start_symbol; lhs < nsyms; lhs++)
    {
      derives[lhs] = rules + k;
      for (i = 0; i < nrules; i++)
    {
      if (rlhs[i] == lhs)
        {
          rules[k] = i;
          k++;
        }
    }
      rules[k] = -1;
      k++;
    }

#ifdef    DEBUG
  print_derives();
#endif
}

free_derives()
{
  FREE(derives[start_symbol]);
  FREE(derives);
}

#ifdef    DEBUG
print_derives()
{
  register int i;
  register short *sp;

  printf("\nDERIVES\n\n");

  for (i = start_symbol; i < nsyms; i++)
    {
      printf("%s derives ", symbol_name[i]);
      for (sp = derives[i]; *sp >= 0; sp++)
    {
      printf("  %d", *sp);
    }
      putchar('\n');
    }

  putchar('\n');
}
#endif


set_nullable()
{
    register int i, j;
    register int empty;
    int done;

    nullable = MALLOC(nsyms);
    if (nullable == 0) no_space();

    for (i = 0; i < nsyms; ++i)
    nullable[i] = 0;

    done = 0;
    while (!done)
    {
    done = 1;
    for (i = 1; i < nitems; i++)
    {
        empty = 1;
        while ((j = ritem[i]) >= 0)
        {
        if (!nullable[j])
            empty = 0;
        ++i;
        }
        if (empty)
        {
        j = rlhs[-j];
        if (!nullable[j])
        {
            nullable[j] = 1;
            done = 0;
        }
        }
    }
    }

#ifdef DEBUG
    for (i = 0; i < nsyms; i++)
    {
    if (nullable[i])
        printf("%s is nullable\n", symbol_name[i]);
    else
        printf("%s is not nullable\n", symbol_name[i]);
    }
#endif
}


free_nullable()
{
  FREE(nullable);
}


lr0()
{
    set_derives();
    set_nullable();
    generate_states();
}