doc/oldfmt.c

   1 /*      Copyright (C) 2000 Free Software Foundation, Inc.
   2  *
   3  * This program is free software; you can redistribute it and/or modify
   4  * it under the terms of the GNU General Public License as published by
   5  * the Free Software Foundation; either version 2, or (at your option)
   6  * any later version.
   7  *
   8  * This program 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
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License
  14  * along with this software; see the file COPYING.  If not, write to
  15  * the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  16  * Boston, MA 02111-1307 USA
  17  *
  18  * As a special exception, the Free Software Foundation gives permission
  19  * for additional uses of the text contained in its release of GUILE.
  20  *
  21  * The exception is that, if you link the GUILE library with other files
  22  * to produce an executable, this does not by itself cause the
  23  * resulting executable to be covered by the GNU General Public License.
  24  * Your use of that executable is in no way restricted on account of
  25  * linking the GUILE library code into it.
  26  *
  27  * This exception does not however invalidate any other reasons why
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  29  *
  30  * This exception applies only to the code released by the
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  41  */
  42
  43 \f
  44
  45 /* From NEWS:
  46  *
  47  * * New primitive: `simple-format', affects `scm-error', scm_display_error, & scm_error message strings
  48  *
  49  * (ice-9 boot) makes `format' an alias for `simple-format' until possibly
  50  * extended by the more sophisticated version in (ice-9 format)
  51  *
  52  * (simple-format port message . args)
  53  * Write MESSAGE to DESTINATION, defaulting to `current-output-port'.
  54  * MESSAGE can contain ~A (was %s) and ~S (was %S) escapes.  When printed,
  55  * the escapes are replaced with corresponding members of ARGS:
  56  * ~A formats using `display' and ~S formats using `write'.
  57  * If DESTINATION is #t, then use the `current-output-port',
  58  * if DESTINATION is #f, then return a string containing the formatted text.
  59  * Does not add a trailing newline."
  60  *
  61  * The two C procedures: scm_display_error and scm_error, as well as the
  62  * primitive `scm-error', now use scm_format to do their work.  This means
  63  * that the message strings of all code must be updated to use ~A where %s
  64  * was used before, and ~S where %S was used before.
  65  *
  66  * During the period when there still are a lot of old Guiles out there,
  67  * you might want to support both old and new versions of Guile.
  68  *
  69  * There are basically two methods to achieve this.  Both methods use
  70  * autoconf.  Put
  71  *
  72  *   AC_CHECK_FUNCS(scm_simple_format)
  73  *
  74  * in your configure.in.
  75  *
  76  * Method 1: Use the string concatenation features of ANSI C's
  77  *           preprocessor.
  78  *
  79  * In C:
  80  *
  81  * #ifdef HAVE_SCM_SIMPLE_FORMAT
  82  * #define FMT_S "~S"
  83  * #else
  84  * #define FMT_S "%S"
  85  * #endif
  86  *
  87  * Then represent each of your error messages using a preprocessor macro:
  88  *
  89  * #define E_SPIDER_ERROR "There's a spider in your " ## FMT_S ## "!!!"
  90  *
  91  * In Scheme:
  92  *
  93  * (define fmt-s (if (defined? 'simple-format) "~S" "%S"))
  94  * (define make-message string-append)
  95  *
  96  * (define e-spider-error
  97  *         (make-message "There's a spider in your " fmt-s "!!!"))
  98  *
  99  * Method 2: Use the oldfmt function found in doc/oldfmt.c.
 100  *
 101  * In C:
 102  *
 103  * scm_misc_error ("picnic", scm_c_oldfmt0 ("There's a spider in your ~S!!!"),
 104  *                 ...);
 105  *
 106  * In Scheme:
 107  *
 108  * (scm-error 'misc-error "picnic" (oldfmt "There's a spider in your ~S!!!")
 109  *            ...)
 110  *
 111  */
 112
 113 /*
 114  * Take a format string FROM adhering to the new standard format (~A and ~S
 115  * as placeholders) of length N and return a string which is adapted
 116  * to the format used by the Guile interpreter which you are running.
 117  *
 118  * On successive calls with similar strings but different storage, the
 119  * same string with same storage is returned.  This is necessary since
 120  * the existence of a garbage collector in the system may cause the same
 121  * format string to be represented with different storage at different
 122  * calls.
 123  */
 124
 125 char *
 126 scm_c_oldfmt (char *from, int n)
 127 {
 128 #ifdef HAVE_SCM_SIMPLE_FORMAT
 129   return from;
 130 #else
 131   static struct { int n; char *from; char *to; } *strings;
 132   static int size = 0;
 133   static int n_strings = 0;
 134   char *to;
 135   int i;
 136
 137   for (i = 0; i < n_strings; ++i)
 138     if (n == strings[i].n && strncmp (from, strings[i].from, n) == 0)
 139       return strings[i].to;
 140
 141   if (n_strings == size)
 142     {
 143       if (size == 0)
 144         {
 145           size = 10;
 146           strings = scm_must_malloc (size * sizeof (*strings), s_oldfmt);
 147         }
 148       else
 149         {
 150           int oldsize = size;
 151           size = 3 * oldsize / 2;
 152           strings = scm_must_realloc (strings,
 153                                       oldsize * sizeof (*strings),
 154                                       size * sizeof (*strings),
 155                                       s_oldfmt);
 156         }
 157     }
 158
 159   strings[n_strings].n = n;
 160   strings[n_strings].from = strncpy (scm_must_malloc (n, s_oldfmt), from, n);
 161   to = strings[n_strings].to = scm_must_malloc (n + 1, s_oldfmt);
 162   n_strings++;
 163
 164   for (i = 0; i < n; ++i)
 165     {
 166       if (from[i] == '~' && ++i < n)
 167         {
 168           if (from[i] == 'A')
 169             {
 170               to[i - 1] = '%';
 171               to[i] = 's';
 172             }
 173           else if (from[i] == 'S')
 174             {
 175               to[i - 1] = '%';
 176               to[i] = 'S';
 177             }
 178           else
 179             {
 180               to[i - 1] = '~';
 181               to[i] = from[i];
 182             }
 183           continue;
 184         }
 185       to[i] = from[i];
 186     }
 187   to[i] = '\0';
 188
 189   return to;
 190 #endif
 191 }
 192
 193 char *
 194 scm_c_oldfmt0 (char *s)
 195 {
 196 #ifdef HAVE_SCM_SIMPLE_FORMAT
 197   return s;
 198 #else
 199   return scm_c_oldfmt (s, strlen (s));
 200 #endif
 201 }
 202
 203 SCM_PROC (s_oldfmt, "oldfmt", 1, 0, 0, scm_oldfmt);
 204
 205 SCM
 206 scm_oldfmt (SCM s)
 207 {
 208 #ifdef HAVE_SCM_SIMPLE_FORMAT
 209   return s;
 210 #else
 211   int n;
 212   SCM_ASSERT (SCM_NIMP (s) && SCM_STRINGP (s), s, 1, s_oldfmt);
 213   n = SCM_LENGTH (s);
 214   return scm_return_first (scm_makfromstr (scm_c_oldfmt (SCM_ROCHARS (s), n),
 215                                            n,
 216                                            0),
 217                            s);
 218 #endif
 219 }