Function luaH_resize

3rd/lua-5.4.3/src/ltable.c:542–576

** Resize table 't' for the new given sizes. Both allocations (for ** the hash part and for the array part) can fail, which creates some ** subtleties. If the first allocation, for the hash part, fails, an ** error is raised and that is it. Otherwise, it copies the elements from ** the shrinking part of the array (if it is shrinking) into the new ** hash. Then it reallocates the array part. If th

** parts of the table.
*/
void luaH_resize (lua_State *L, Table *t, unsigned int newasize,
                                          unsigned int nhsize) {
  unsigned int i;
  Table newt;  /* to keep the new hash part */
  unsigned int oldasize = setlimittosize(t);
  TValue *newarray;
  /* create new hash part with appropriate size into 'newt' */
  setnodevector(L, &newt, nhsize);
  if (newasize < oldasize) {  /* will array shrink? */
    t->alimit = newasize;  /* pretend array has new size... */
    exchangehashpart(t, &newt);  /* and new hash */
    /* re-insert into the new hash the elements from vanishing slice */
    for (i = newasize; i < oldasize; i++) {
      if (!isempty(&t->array[i]))
        luaH_setint(L, t, i + 1, &t->array[i]);
    }
    t->alimit = oldasize;  /* restore current size... */
    exchangehashpart(t, &newt);  /* and hash (in case of errors) */
  }
  /* allocate new array */
  newarray = luaM_reallocvector(L, t->array, oldasize, newasize, TValue);
  if (l_unlikely(newarray == NULL && newasize > 0)) {  /* allocation failed? */
    freehash(L, &newt);  /* release new hash part */
    luaM_error(L);  /* raise error (with array unchanged) */
  }
  /* allocation ok; initialize new part of the array */
  exchangehashpart(t, &newt);  /* 't' has the new hash ('newt' has the old) */
  t->array = newarray;  /* set new array part */
  t->alimit = newasize;
  for (i = oldasize; i < newasize; i++)  /* clear new slice of the array */
     setempty(&t->array[i]);
  /* re-insert elements from old hash part into new parts */
  reinsert(L, &newt, t);  /* 'newt' now has the old hash */
  freehash(L, &newt);  /* free old hash part */
}


void luaH_resizearray (lua_State *L, Table *t, unsigned int nasize) {