libguile/options.c

   1 /*      Copyright (C) 1995, 1996, 1998, 2000, 2001 Free Software Foundation
   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
  28  * the executable file might be covered by the GNU General Public License.
  29  *
  30  * This exception applies only to the code released by the
  31  * Free Software Foundation under the name GUILE.  If you copy
  32  * code from other Free Software Foundation releases into a copy of
  33  * GUILE, as the General Public License permits, the exception does
  34  * not apply to the code that you add in this way.  To avoid misleading
  35  * anyone as to the status of such modified files, you must delete
  36  * this exception notice from them.
  37  *
  38  * If you write modifications of your own for GUILE, it is your choice
  39  * whether to permit this exception to apply to your modifications.
  40  * If you do not wish that, delete this exception notice.
  41  *
  42  * The author can be reached at djurfeldt@nada.kth.se
  43  * Mikael Djurfeldt, SANS/NADA KTH, 10044 STOCKHOLM, SWEDEN */
  44
  45
  46 \f
  47
  48 #include "libguile/_scm.h"
  49 #include "libguile/strings.h"
  50
  51 #include "libguile/options.h"
  52 \f
  53
  54 /* {Run-time options}
  55  *
  56  * This is the basic interface for low-level configuration of the
  57  * Guile library.  It is used for configuring the reader, evaluator,
  58  * printer and debugger.
  59  *
  60  * Motivation:
  61  *
  62  * 1. Altering option settings can have side effects.
  63  * 2. Option values can be stored in native format.
  64  *    (Important for efficiency in, e. g., the evaluator.)
  65  * 3. Doesn't use up name space.
  66  * 4. Options can be naturally grouped => ease of use.
  67  */
  68
  69 /* scm_options is the core of all options interface procedures.
  70  *
  71  * Some definitions:
  72  *
  73  * Run time options in Guile are arranged in groups.  Each group
  74  * affects a certain aspect of the behaviour of the library.
  75  *
  76  * An "options interface procedure" manages one group of options.  It
  77  * can be used to check or set options, or to get documentation for
  78  * all options of a group.  The options interface procedure is not
  79  * intended to be called directly by the user.  The user should
  80  * instead call
  81  *
  82  *   (<group>-options)
  83  *   (<group>-options 'help)
  84  *   (<group>-options 'full)
  85  *
  86  * to display current option settings (The second version also
  87  * displays documentation.  The third version also displays
  88  * information about programmer's options.), and
  89  *
  90  *   (<group>-enable  '<option-symbol>)
  91  *   (<group>-disable '<option-symbol>)
  92  *   (<group>-set! <option-symbol> <value>)
  93  *   (<group>-options <option setting>)
  94  *
  95  * to alter the state of an option  (The last version sets all
  96  * options according to <option setting>.) where <group> is the name
  97  * of the option group.
  98  *
  99  * An "option setting" represents the state of all low-level options
 100  * managed by one options interface procedure.  It is a list of
 101  * single symbols and symbols followed by a value.
 102  *
 103  * For boolean options, the presence of the symbol of that option in
 104  * the option setting indicates a true value.  If the symbol isn't a
 105  * member of the option setting this represents a false value.
 106  *
 107  * Other options are represented by a symbol followed by the value.
 108  *
 109  * If scm_options is called without arguments, the current option
 110  * setting is returned.  If the argument is an option setting, options
 111  * are altered and the old setting is returned.  If the argument isn't
 112  * a list, a list of sublists is returned, where each sublist contains
 113  * option name, value and documentation string.
 114  */
 115
 116 SCM_SYMBOL (scm_yes_sym, "yes");
 117 SCM_SYMBOL (scm_no_sym, "no");
 118
 119 static SCM protected_objects;
 120
 121 SCM
 122 scm_options (SCM arg, scm_t_option options[], int n, const char *s)
 123 {
 124   int i, docp = (!SCM_UNBNDP (arg) && !SCM_NULLP (arg) && !SCM_CONSP (arg));
 125   /* Let `arg' GC protect the arguments */
 126   SCM new_mode = arg, ans = SCM_EOL, ls;
 127   for (i = 0; i < n; ++i)
 128     {
 129       ls = docp ? scm_cons ((SCM) options[i].doc, SCM_EOL) : ans;
 130       switch (options[i].type)
 131         {
 132         case SCM_OPTION_BOOLEAN:
 133           if (docp)
 134             ls = scm_cons ((int) options[i].val
 135                            ? scm_yes_sym
 136                            : scm_no_sym,
 137                            ls);
 138           break;
 139         case SCM_OPTION_INTEGER:
 140           ls = scm_cons (SCM_MAKINUM (options[i].val), ls);
 141           break;
 142         case SCM_OPTION_SCM:
 143           ls = scm_cons ((SCM) options[i].val, ls);
 144         }
 145       if (!((options[i].type == SCM_OPTION_BOOLEAN)
 146             && !docp
 147             && ! (int) options[i].val))
 148         ls = scm_cons ((SCM) options[i].name, ls);
 149       ans = docp ? scm_cons (ls, ans) : ls;
 150     }
 151   if (!(SCM_UNBNDP (new_mode) || docp))
 152     {
 153       unsigned long *flags;
 154       flags = (unsigned long *) scm_must_malloc (n * sizeof (unsigned long),
 155                                                  "mode buffer");
 156       for (i = 0; i < n; ++i)
 157         if (options[i].type == SCM_OPTION_BOOLEAN)
 158           flags[i] = 0;
 159         else
 160           flags[i] = (unsigned long) options[i].val;
 161       while (SCM_NNULLP (new_mode))
 162         {
 163           SCM_ASSERT (SCM_CONSP (new_mode),
 164                       new_mode,
 165                       SCM_ARG1,
 166                       s);
 167           for (i = 0; i < n; ++i)
 168             if (SCM_CAR (new_mode) == (SCM) options[i].name)
 169               switch (options[i].type)
 170                 {
 171                 case SCM_OPTION_BOOLEAN:
 172                   flags[i] = 1;
 173                   goto cont;
 174                 case SCM_OPTION_INTEGER:
 175                   new_mode = SCM_CDR (new_mode);
 176                   SCM_ASSERT (   SCM_CONSP (new_mode)
 177                               && SCM_INUMP (SCM_CAR (new_mode)),
 178                               new_mode,
 179                               SCM_ARG1,
 180                               s);
 181                   flags[i] = (unsigned long) SCM_INUM (SCM_CAR (new_mode));
 182                   goto cont;
 183                 case SCM_OPTION_SCM:
 184                   new_mode = SCM_CDR (new_mode);
 185                   flags[i] = SCM_UNPACK (SCM_CAR (new_mode));
 186                   goto cont;
 187                 }
 188 #ifndef SCM_RECKLESS
 189           scm_must_free ((char *) flags);
 190           scm_misc_error (s, "Unknown mode flag: ~S",
 191                           scm_list_1 (SCM_CAR (new_mode)));
 192 #endif
 193         cont:
 194           new_mode = SCM_CDR (new_mode);
 195         }
 196       for (i = 0; i < n; ++i)
 197         {
 198           /* scm_option doesn't know if its a long or an SCM */
 199           if (options[i].type == SCM_OPTION_SCM)
 200             SCM_SETCDR (protected_objects,
 201                         scm_cons (SCM_PACK(flags[i]),
 202                                   scm_delq1_x (SCM_PACK(options[i].val),
 203                                                SCM_CDR (protected_objects))));
 204           options[i].val = flags[i];
 205         }
 206       scm_must_free ((char *) flags);
 207     }
 208   return ans;
 209 }
 210
 211
 212 void
 213 scm_init_opts (SCM (*func) (SCM), scm_t_option options[], int n)
 214 {
 215   int i;
 216
 217   for (i = 0; i < n; ++i)
 218     {
 219       SCM name;
 220       SCM doc;
 221
 222       name = scm_str2symbol (options[i].name);
 223       options[i].name = (char *) name;
 224       scm_permanent_object (name);
 225       doc = scm_take0str (options[i].doc);
 226       options[i].doc = (char *) doc;
 227       scm_permanent_object (doc);
 228       if (options[i].type == SCM_OPTION_SCM)
 229         SCM_SETCDR (protected_objects,
 230                     scm_cons (SCM_PACK(options[i].val), SCM_CDR (protected_objects)));
 231     }
 232   func (SCM_UNDEFINED);
 233 }
 234
 235
 236 void
 237 scm_init_options ()
 238 {
 239   protected_objects = scm_permanent_object (scm_cons (SCM_UNDEFINED, SCM_EOL));
 240 #ifndef SCM_MAGIC_SNARFER
 241 #include "libguile/options.x"
 242 #endif
 243 }
 244
 245 /*
 246   Local Variables:
 247   c-file-style: "gnu"
 248   End:
 249 */