/* Printf Extension Example

   Copyright (C) 1991-2018 Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or

   modify it under the terms of the GNU General Public License

   as published by the Free Software Foundation; either version 2

   of the License, or (at your option) any later version.

   This program is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License

   along with this program; if not, if not, see <http://www.gnu.org/licenses/>.

*/

#include <stdio.h>

#include <stdlib.h>

#include <printf.h>

/*@group*/

typedef struct

{

  char *name;

}

Widget;

/*@end group*/

int

print_widget (FILE *stream,

	      const struct printf_info *info,

	      const void *const *args)

{

  const Widget *w;

  char *buffer;

  int len;

  /* Format the output into a string. */

  w = *((const Widget **) (args[0]));

  len = asprintf (&buffer, "<Widget %p: %s>", w, w->name);

  if (len == -1)

    return -1;

  /* Pad to the minimum field width and print to the stream. */

  len = fprintf (stream, "%*s",

		 (info->left ? -info->width : info->width),

		 buffer);

  /* Clean up and return. */

  free (buffer);

  return len;

}

int

print_widget_arginfo (const struct printf_info *info, size_t n,

                      int *argtypes)

{

  /* We always take exactly one argument and this is a pointer to the

     structure..  */

  if (n > 0)

    argtypes[0] = PA_POINTER;

  return 1;

}

int

main (void)

{

  /* Make a widget to print. */

  Widget mywidget;

  mywidget.name = "mywidget";

  /* Register the print function for widgets. */

  register_printf_function ('W', print_widget, print_widget_arginfo);

  /* Now print the widget. */

  printf ("|%W|\n", &mywidget);

  printf ("|%35W|\n", &mywidget);

  printf ("|%-35W|\n", &mywidget);

  return 0;

}