doc/oldfmt.c

   1 /* Copyright (C) 2000,2001, 2006, 2008 Free Software Foundation, Inc.
   2  *
   3  * This library is free software; you can redistribute it and/or
   4  * modify it under the terms of the GNU Lesser General Public
   5  * License as published by the Free Software Foundation; either
   6  * version 2.1 of the License, or (at your option) any later version.
   7  *
   8  * This library is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * Lesser General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU Lesser General Public
  14  * License along with this library; if not, write to the Free Software
  15  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  16  */
  17
  18 \f
  19
  20 /* From NEWS:
  21  *
  22  * * New primitive: `simple-format', affects `scm-error', scm_display_error, & scm_error message strings
  23  *
  24  * (ice-9 boot) makes `format' an alias for `simple-format' until possibly
  25  * extended by the more sophisticated version in (ice-9 format)
  26  *
  27  * (simple-format port message . args)
  28  * Write MESSAGE to DESTINATION, defaulting to `current-output-port'.
  29  * MESSAGE can contain ~A (was %s) and ~S (was %S) escapes.  When printed,
  30  * the escapes are replaced with corresponding members of ARGS:
  31  * ~A formats using `display' and ~S formats using `write'.
  32  * If DESTINATION is #t, then use the `current-output-port',
  33  * if DESTINATION is #f, then return a string containing the formatted text.
  34  * Does not add a trailing newline."
  35  *
  36  * The two C procedures: scm_display_error and scm_error, as well as the
  37  * primitive `scm-error', now use scm_format to do their work.  This means
  38  * that the message strings of all code must be updated to use ~A where %s
  39  * was used before, and ~S where %S was used before.
  40  *
  41  * During the period when there still are a lot of old Guiles out there,
  42  * you might want to support both old and new versions of Guile.
  43  *
  44  * There are basically two methods to achieve this.  Both methods use
  45  * autoconf.  Put
  46  *
  47  *   AC_CHECK_FUNCS(scm_simple_format)
  48  *
  49  * in your configure.in.
  50  *
  51  * Method 1: Use the string concatenation features of ANSI C's
  52  *           preprocessor.
  53  *
  54  * In C:
  55  *
  56  * #ifdef HAVE_SCM_SIMPLE_FORMAT
  57  * #define FMT_S "~S"
  58  * #else
  59  * #define FMT_S "%S"
  60  * #endif
  61  *
  62  * Then represent each of your error messages using a preprocessor macro:
  63  *
  64  * #define E_SPIDER_ERROR "There's a spider in your " ## FMT_S ## "!!!"
  65  *
  66  * In Scheme:
  67  *
  68  * (define fmt-s (if (defined? 'simple-format) "~S" "%S"))
  69  * (define make-message string-append)
  70  *
  71  * (define e-spider-error
  72  *         (make-message "There's a spider in your " fmt-s "!!!"))
  73  *
  74  * Method 2: Use the oldfmt function found in doc/oldfmt.c.
  75  *
  76  * In C:
  77  *
  78  * scm_misc_error ("picnic", scm_c_oldfmt0 ("There's a spider in your ~S!!!"),
  79  *                 ...);
  80  *
  81  * In Scheme:
  82  *
  83  * (scm-error 'misc-error "picnic" (oldfmt "There's a spider in your ~S!!!")
  84  *            ...)
  85  *
  86  */
  87
  88 /*
  89  * Take a format string FROM adhering to the new standard format (~A and ~S
  90  * as placeholders) of length N and return a string which is adapted
  91  * to the format used by the Guile interpreter which you are running.
  92  *
  93  * On successive calls with similar strings but different storage, the
  94  * same string with same storage is returned.  This is necessary since
  95  * the existence of a garbage collector in the system may cause the same
  96  * format string to be represented with different storage at different
  97  * calls.
  98  */
  99
 100 char *
 101 scm_c_oldfmt (char *from, int n)
 102 {
 103 #ifdef HAVE_SCM_SIMPLE_FORMAT
 104   return from;
 105 #else
 106   static struct { int n; char *from; char *to; } *strings;
 107   static int size = 0;
 108   static int n_strings = 0;
 109   char *to;
 110   int i;
 111
 112   for (i = 0; i < n_strings; ++i)
 113     if (n == strings[i].n && strncmp (from, strings[i].from, n) == 0)
 114       return strings[i].to;
 115
 116   if (n_strings == size)
 117     {
 118       if (size == 0)
 119         {
 120           size = 10;
 121           strings = scm_must_malloc (size * sizeof (*strings), s_oldfmt);
 122         }
 123       else
 124         {
 125           int oldsize = size;
 126           size = 3 * oldsize / 2;
 127           strings = scm_must_realloc (strings,
 128                                       oldsize * sizeof (*strings),
 129                                       size * sizeof (*strings),
 130                                       s_oldfmt);
 131         }
 132     }
 133
 134   strings[n_strings].n = n;
 135   strings[n_strings].from = strncpy (scm_must_malloc (n, s_oldfmt), from, n);
 136   to = strings[n_strings].to = scm_must_malloc (n + 1, s_oldfmt);
 137   n_strings++;
 138
 139   for (i = 0; i < n; ++i)
 140     {
 141       if (from[i] == '~' && ++i < n)
 142         {
 143           if (from[i] == 'A')
 144             {
 145               to[i - 1] = '%';
 146               to[i] = 's';
 147             }
 148           else if (from[i] == 'S')
 149             {
 150               to[i - 1] = '%';
 151               to[i] = 'S';
 152             }
 153           else
 154             {
 155               to[i - 1] = '~';
 156               to[i] = from[i];
 157             }
 158           continue;
 159         }
 160       to[i] = from[i];
 161     }
 162   to[i] = '\0';
 163
 164   return to;
 165 #endif
 166 }
 167
 168 char *
 169 scm_c_oldfmt0 (char *s)
 170 {
 171 #ifdef HAVE_SCM_SIMPLE_FORMAT
 172   return s;
 173 #else
 174   return scm_c_oldfmt (s, strlen (s));
 175 #endif
 176 }
 177
 178 SCM_PROC (s_oldfmt, "oldfmt", 1, 0, 0, scm_oldfmt);
 179
 180 SCM
 181 scm_oldfmt (SCM s)
 182 {
 183 #ifdef HAVE_SCM_SIMPLE_FORMAT
 184   return s;
 185 #else
 186   int n;
 187   SCM_ASSERT (SCM_NIMP (s) && SCM_STRINGP (s), s, 1, s_oldfmt);
 188   n = SCM_LENGTH (s);
 189   return scm_return_first (scm_mem2string (scm_c_oldfmt (SCM_ROCHARS (s), n),
 190                                            n),
 191                            s);
 192 #endif
 193 }