unistdio (was: Re: new module 'printf-frexpl')

[Bruno Haible]

Daniel Jacobowitz wrote:
> Could you tell me a little bit about unistdio

It's a set of *printf functions for Unicode strings, part of a Unicode string
library that I presented here: [1]. Its include file unistdio.h is appended.

> and how it interacts with (A) the printf we already have,

The interface is very similar to the C99 / POSIX printf; the differences
are
  - the %U directive which accepts a Unicode string argument, even when
    producing a plain 'char *' string or a Unicode string of different width,
  - there are also variants which take an ASCII 'char *' format string
    and produce UTF-16 or UTF-32 results.

The code is similar to vasnprintf.h but with different sets of #ifdefs.
If both implementations were merged, it would become too much of an #if
spaghetti, IMO.

> and (B) the printf I spent all weekend working on merging?

So far, it's unrelated. snprintfv lets me define my own handler for
%U or similar, but I don't see how to produce UTF-16 or UTF-32 strings
with snprintfv, and how to take UTF-16 or UTF-32 strings as arguments
without dirty casting.

> I'm worried that gnulib is developing too
> many different ways to do almost the same thing, all slightly different.

Well, I'm not particularly happy about 'canonicalize' vs. 'canonicalize-lgpl'
or 'xreadlink' vs. 'xreadlink_with_size' either. But the positive side is
that we dare to create a different function if it's useful and needed (even
if a similar function already exists). And that we still do a good amount
of code sharing (look for example how many modules use m4/longdouble.m4
or xstrtol.c).

Different approaches must compete sometimes; there is for example no unique
optimal way to implement a hash table, therefore it's normal that we have
more than one hash table code in gnulib. Let people choose what they need.

      Bruno


[1] http://lists.gnu.org/archive/html/bug-gnulib/2007-01/msg00079.html

=============================== unistdio.h ===================================
/* Elementary Unicode string functions.
   Copyright (C) 2002, 2005-2007 Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or modify it
   under the terms of the GNU Library General Public License as published
   by the Free Software Foundation; either version 2, 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
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
   USA.  */

#ifndef _UNISTDIO_H
#define _UNISTDIO_H

#include "unitypes.h"

/* Get size_t.  */
#include <stddef.h>

/* Get FILE.  */
#include <stdio.h>

/* Get va_list.  */
#include <stdarg.h>

#ifdef __cplusplus
extern "C" {
#endif

/* These work like the printf function family.
   In the format string:
   The format directive 'U' takes an UTF-8 string (const uint8_t *).
   The format directive 'lU' takes an UTF-16 string (const uint16_t *).
   The format directive 'llU' takes an UTF-32 string (const uint32_t *).

   The prefix (ulc_, u8_, u16_, u16_) indicates the type of the resulting
   string.  The prefix 'ulc' stands for "locale encoded".

   An infix 'v' indicates that a va_list is passed instead of multiple
   arguments.

   The functions *sprintf have a 'buf' argument that is assumed to be large
   enough.  (DANGEROUS!  Overflowing the buffer will crash the program.)
   The functions *snprintf have a 'buf' argument that is assumed to be 'size'
   units large.  (DANGEROUS!  The resulting string might be truncated in the
   middle of a multibyte character.)
   The functions *asprintf have a 'resultp' argument.  The result will be
   freshly allocated and stored in *resultp.
   The functions *asnprintf have a (resultbuf, lengthp) argument pair.  If
   resultbuf is not NULL and the result fits into *lengthp units, it is put
   in resultbuf, and resultbuf is returned.  Otherwise, a freshly allocated
   string is returned.  In both cases, *lengthp is set to the length (number
   of units) of the returned string.  In case of error, NULL is returned and
   errno is set.
 */

/* ASCII format string, result in locale dependent encoded 'char *'.  */
extern int
       ulc_sprintf (char *buf,
                    const char *format, ...);
extern int
       ulc_snprintf (char *buf, size_t size,
                     const char *format, ...);
extern int
       ulc_asprintf (char **resultp,
                     const char *format, ...);
extern char *
       ulc_asnprintf (char *resultbuf, size_t *lengthp,
                      const char *format, ...);
extern int
       ulc_vsprintf (char *buf,
                     const char *format, va_list ap);
extern int
       ulc_vsnprintf (char *buf, size_t size,
                      const char *format, va_list ap);
extern int
       ulc_vasprintf (char **resultp,
                      const char *format, va_list ap);
extern char *
       ulc_vasnprintf (char *resultbuf, size_t *lengthp,
                       const char *format, va_list ap);

/* ASCII format string, result in UTF-8 format.  */
extern int
       u8_sprintf (uint8_t *buf,
                   const char *format, ...);
extern int
       u8_snprintf (uint8_t *buf, size_t size,
                    const char *format, ...);
extern int
       u8_asprintf (uint8_t **resultp,
                    const char *format, ...);
extern uint8_t *
       u8_asnprintf (uint8_t *resultbuf, size_t *lengthp,
                     const char *format, ...);
extern int
       u8_vsprintf (uint8_t *buf,
                    const char *format, va_list ap);
extern int
       u8_vsnprintf (uint8_t *buf, size_t size,
                     const char *format, va_list ap);
extern int
       u8_vasprintf (uint8_t **resultp,
                     const char *format, va_list ap);
extern uint8_t *
       u8_vasnprintf (uint8_t *resultbuf, size_t *lengthp,
                      const char *format, va_list ap);

/* UTF-8 format string, result in UTF-8 format.  */
extern int
       u8_u8_sprintf (uint8_t *buf,
                      const uint8_t *format, ...);
extern int
       u8_u8_snprintf (uint8_t *buf, size_t size,
                       const uint8_t *format, ...);
extern int
       u8_u8_asprintf (uint8_t **resultp,
                       const uint8_t *format, ...);
extern uint8_t *
       u8_u8_asnprintf (uint8_t *resultbuf, size_t *lengthp,
                        const uint8_t *format, ...);
extern int
       u8_u8_vsprintf (uint8_t *buf,
                       const uint8_t *format, va_list ap);
extern int
       u8_u8_vsnprintf (uint8_t *buf, size_t size,
                        const uint8_t *format, va_list ap);
extern int
       u8_u8_vasprintf (uint8_t **resultp,
                        const uint8_t *format, va_list ap);
extern uint8_t *
       u8_u8_vasnprintf (uint8_t *resultbuf, size_t *lengthp,
                         const uint8_t *format, va_list ap);

/* ASCII format string, result in UTF-16 format.  */
extern int
       u16_sprintf (uint16_t *buf,
                    const char *format, ...);
extern int
       u16_snprintf (uint16_t *buf, size_t size,
                     const char *format, ...);
extern int
       u16_asprintf (uint16_t **resultp,
                     const char *format, ...);
extern uint16_t *
       u16_asnprintf (uint16_t *resultbuf, size_t *lengthp,
                      const char *format, ...);
extern int
       u16_vsprintf (uint16_t *buf,
                     const char *format, va_list ap);
extern int
       u16_vsnprintf (uint16_t *buf, size_t size,
                      const char *format, va_list ap);
extern int
       u16_vasprintf (uint16_t **resultp,
                      const char *format, va_list ap);
extern uint16_t *
       u16_vasnprintf (uint16_t *resultbuf, size_t *lengthp,
                       const char *format, va_list ap);

/* UTF-16 format string, result in UTF-16 format.  */
extern int
       u16_u16_sprintf (uint16_t *buf,
                        const uint16_t *format, ...);
extern int
       u16_u16_snprintf (uint16_t *buf, size_t size,
                         const uint16_t *format, ...);
extern int
       u16_u16_asprintf (uint16_t **resultp,
                         const uint16_t *format, ...);
extern uint16_t *
       u16_u16_asnprintf (uint16_t *resultbuf, size_t *lengthp,
                          const uint16_t *format, ...);
extern int
       u16_u16_vsprintf (uint16_t *buf,
                         const uint16_t *format, va_list ap);
extern int
       u16_u16_vsnprintf (uint16_t *buf, size_t size,
                          const uint16_t *format, va_list ap);
extern int
       u16_u16_vasprintf (uint16_t **resultp,
                          const uint16_t *format, va_list ap);
extern uint16_t *
       u16_u16_vasnprintf (uint16_t *resultbuf, size_t *lengthp,
                           const uint16_t *format, va_list ap);

/* ASCII format string, result in UTF-32 format.  */
extern int
       u32_sprintf (uint32_t *buf,
                    const char *format, ...);
extern int
       u32_snprintf (uint32_t *buf, size_t size,
                     const char *format, ...);
extern int
       u32_asprintf (uint32_t **resultp,
                     const char *format, ...);
extern uint32_t *
       u32_asnprintf (uint32_t *resultbuf, size_t *lengthp,
                      const char *format, ...);
extern int
       u32_vsprintf (uint32_t *buf,
                     const char *format, va_list ap);
extern int
       u32_vsnprintf (uint32_t *buf, size_t size,
                      const char *format, va_list ap);
extern int
       u32_vasprintf (uint32_t **resultp,
                      const char *format, va_list ap);
extern uint32_t *
       u32_vasnprintf (uint32_t *resultbuf, size_t *lengthp,
                       const char *format, va_list ap);

/* UTF-32 format string, result in UTF-32 format.  */
extern int
       u32_u32_sprintf (uint32_t *buf,
                        const uint32_t *format, ...);
extern int
       u32_u32_snprintf (uint32_t *buf, size_t size,
                         const uint32_t *format, ...);
extern int
       u32_u32_asprintf (uint32_t **resultp,
                         const uint32_t *format, ...);
extern uint32_t *
       u32_u32_asnprintf (uint32_t *resultbuf, size_t *lengthp,
                          const uint32_t *format, ...);
extern int
       u32_u32_vsprintf (uint32_t *buf,
                         const uint32_t *format, va_list ap);
extern int
       u32_u32_vsnprintf (uint32_t *buf, size_t size,
                          const uint32_t *format, va_list ap);
extern int
       u32_u32_vasprintf (uint32_t **resultp,
                          const uint32_t *format, va_list ap);
extern uint32_t *
       u32_u32_vasnprintf (uint32_t *resultbuf, size_t *lengthp,
                           const uint32_t *format, va_list ap);

/* ASCII format string, output to FILE in locale dependent encoding.  */
extern int
       ulc_fprintf (FILE *stream,
                    const char *format, ...);
extern int
       ulc_vfprintf (FILE *stream,
                     const char *format, va_list ap);

#ifdef __cplusplus
}
#endif

#endif /* _UNISTDIO_H */