pike.git/ src/ builtin.cmod

Branch: Tag:

2019-06-24

2019-06-24 16:25:52 by Henrik Grubbström (Grubba) <grubba@grubba.org>

ADT.Stack: Added pop_to().

This is useful to undo an unknown number of push()es.

6650:    *! from the top. If no value is given the top element is    *! popped and returned. All popped entries are freed from    *! the stack. +  *! +  *! @seealso +  *! @[quick_pop()], @[pop_to()]    */    PIKEFUN mixed pop(void|int val)    {
6670:    THIS->arr->size = new_size;    Pike_sp++;    +  /* NB: +1 to skip freeing the returned element. */    free_svalues(ITEM(THIS->arr) + new_size + 1, old_size - (new_size + 1),    THIS->arr->type_field);    } else {
6684:    *! Pops @[val] entries from the stack, or one entry    *! if no value is given. The popped entries are not    *! returned. +  *! +  *! @seealso +  *! @[pop()], @[pop_to()]    */    PIKEFUN void quick_pop(void|int val)    {
6691:    push_int(0);    }    +  /*! @decl void pop_to(int depth) +  *! +  *! Pops entries from the stack until it reaches the specified depth. +  *! +  *! The popped entries are not returned. +  *! +  *! @throws +  *! Throws an error if there are fewer than @[depth] elements +  *! on the stack. +  *! +  *! @seealso +  *! @[pop()], @[quick_pop()] +  */ +  PIKEFUN void pop_to(int depth) +  { +  ptrdiff_t old_size; +  +  if (!THIS->arr) { +  if (!depth) return; +  Pike_error("Stack underflow.\n"); +  } +  +  if ((depth < 0) || (THIS->arr->size < depth)) { +  Pike_error("Stack underflow.\n"); +  } +  +  old_size = THIS->arr->size; +  if (old_size == depth) return; /* NOOP */ +  +  if (!depth) { /* Pop all. */ +  free_array(THIS->arr); +  THIS->arr = NULL; +  return; +  } +  +  THIS->arr->size = depth; +  +  free_svalues(ITEM(THIS->arr) + depth, old_size - depth, +  THIS->arr->type_field); +  } +     /*! @decl void reset(int|void initial_size)    *! Empties the stack, resets the stack pointer    *! and shrinks the stack size to the given value