Re: stack module

[Marc Nieper-Wißkirchen]

So here is the updated stack module. The name "CLEAR" has been changed
to "DESTROY" as suggested by Bruno. Error checking has been included.
The macro interface remains. Although a macro interface means macros,
the macros are trivial and the type safety wins here, I think. I have
renamed STACK_BASE to STACK_CURRENT_BASE because the base may be
invalidated when items are pushed onto the stack and reallocation has
to happen.

As I haven't heard anything from the FSF yet, I wouldn't mind if you
considered the following in the public domain...

#ifndef _GL_STACK_H
#define _GL_STACK_H

#include <stddef.h>
#include <stdlib.h>

#include "assure.h"
#include "xalloc.h"

#define STACK(type)                \
  struct {                    \
    type *base;                    \
    size_t size;                \
    size_t allocated;                \
  }

#define STACK_INIT(stack)                \
  do                            \
    {                            \
      (stack).base = NULL;                \
      (stack).size = 0;                    \
      (stack).allocated = 0;                \
    }                            \
  while (0)

#define STACK_DESTROY(stack)            \
  free ((stack).base)

#define STACK_EMPTY(stack)            \
  ((stack).size == 0)

#define STACK_CURRENT_BASE(stack)            \
  ((stack).base)

#define STACK_PUSH(stack, item)                        \
  do                                    \
    {                                    \
      if ((stack).size == (stack).allocated)                \
    (stack).base = x2nrealloc ((stack).base, &(stack).allocated,
sizeof (item)); \
      (stack).base [(stack).size++] = item;                \
    }                                    \
  while (0)

#define STACK_POP(stack)            \
  (affirm (!STACK_EMPTY (stack)), (stack).base [--(stack).size])

#define STACK_DISCARD(stack)            \
  (affirm (!STACK_EMPTY (stack)), (--(stack).size))

#define STACK_TOP(stack)            \
  (affirm (!STACK_EMPTY (stack)), (stack).base[(stack).size - 1)

#define STACK_SIZE(stack)            \
  ((stack).size)

#endif /* _GL_STACK_H */

Am So., 24. Mai 2020 um 21:26 Uhr schrieb Bruno Haible <bruno@clisp.org>:
>
> Paul Eggert wrote:
> > I don't want to encourage programmers to supply an E with side effects, as 
> > side
> > effects are trouble here.
>
> +1
>