libguile/options.c

   1 /* Copyright (C) 1995,1996,1998,2000,2001 Free Software Foundation
   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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  16  */
  17
  18 \f
  19
  20 #include "libguile/_scm.h"
  21 #include "libguile/mallocs.h"
  22 #include "libguile/strings.h"
  23 #include "libguile/lang.h"
  24
  25 #include "libguile/options.h"
  26 \f
  27
  28 /* {Run-time options}
  29  *
  30  * This is the basic interface for low-level configuration of the
  31  * Guile library.  It is used for configuring the reader, evaluator,
  32  * printer and debugger.
  33  *
  34  * Motivation:
  35  *
  36  * 1. Altering option settings can have side effects.
  37  * 2. Option values can be stored in native format.
  38  *    (Important for efficiency in, e. g., the evaluator.)
  39  * 3. Doesn't use up name space.
  40  * 4. Options can be naturally grouped => ease of use.
  41  */
  42
  43 /* scm_options is the core of all options interface procedures.
  44  *
  45  * Some definitions:
  46  *
  47  * Run time options in Guile are arranged in groups.  Each group
  48  * affects a certain aspect of the behaviour of the library.
  49  *
  50  * An "options interface procedure" manages one group of options.  It
  51  * can be used to check or set options, or to get documentation for
  52  * all options of a group.  The options interface procedure is not
  53  * intended to be called directly by the user.  The user should
  54  * instead call
  55  *
  56  *   (<group>-options)
  57  *   (<group>-options 'help)
  58  *   (<group>-options 'full)
  59  *
  60  * to display current option settings (The second version also
  61  * displays documentation.  The third version also displays
  62  * information about programmer's options.), and
  63  *
  64  *   (<group>-enable  '<option-symbol>)
  65  *   (<group>-disable '<option-symbol>)
  66  *   (<group>-set! <option-symbol> <value>)
  67  *   (<group>-options <option setting>)
  68  *
  69  * to alter the state of an option  (The last version sets all
  70  * options according to <option setting>.) where <group> is the name
  71  * of the option group.
  72  *
  73  * An "option setting" represents the state of all low-level options
  74  * managed by one options interface procedure.  It is a list of
  75  * single symbols and symbols followed by a value.
  76  *
  77  * For boolean options, the presence of the symbol of that option in
  78  * the option setting indicates a true value.  If the symbol isn't a
  79  * member of the option setting this represents a false value.
  80  *
  81  * Other options are represented by a symbol followed by the value.
  82  *
  83  * If scm_options is called without arguments, the current option
  84  * setting is returned.  If the argument is an option setting, options
  85  * are altered and the old setting is returned.  If the argument isn't
  86  * a list, a list of sublists is returned, where each sublist contains
  87  * option name, value and documentation string.
  88  */
  89
  90 SCM_SYMBOL (scm_yes_sym, "yes");
  91 SCM_SYMBOL (scm_no_sym, "no");
  92
  93 static SCM protected_objects = SCM_EOL;
  94
  95 /* Return a list of the current option setting.  The format of an
  96  * option setting is described in the above documentation.  */
  97 static SCM
  98 get_option_setting (const scm_t_option options[], unsigned int n)
  99 {
 100   unsigned int i;
 101   SCM ls = SCM_EOL;
 102   for (i = 0; i != n; ++i)
 103     {
 104       switch (options[i].type)
 105         {
 106         case SCM_OPTION_BOOLEAN:
 107           if (options[i].val)
 108             ls = scm_cons (SCM_PACK (options[i].name), ls);
 109           break;
 110         case SCM_OPTION_INTEGER:
 111           ls = scm_cons (scm_from_unsigned_integer (options[i].val), ls);
 112           ls = scm_cons (SCM_PACK (options[i].name), ls);
 113           break;
 114         case SCM_OPTION_SCM:
 115           ls = scm_cons (SCM_PACK (options[i].val), ls);
 116           ls = scm_cons (SCM_PACK (options[i].name), ls);
 117         }
 118     }
 119   return ls;
 120 }
 121
 122
 123 /* Return a list of sublists, where each sublist contains option name, value
 124  * and documentation string.  */
 125 static SCM
 126 get_documented_option_setting (const scm_t_option options[], unsigned int n)
 127 {
 128   SCM ans = SCM_EOL;
 129   unsigned int i;
 130
 131   for (i = 0; i != n; ++i)
 132     {
 133       SCM ls = scm_cons (scm_str2string (options[i].doc), SCM_EOL);
 134       switch (options[i].type)
 135         {
 136         case SCM_OPTION_BOOLEAN:
 137           ls = scm_cons (options[i].val ? scm_yes_sym : scm_no_sym, ls);
 138           break;
 139         case SCM_OPTION_INTEGER:
 140           ls = scm_cons (scm_from_unsigned_integer (options[i].val), ls);
 141           break;
 142         case SCM_OPTION_SCM:
 143           ls = scm_cons (SCM_PACK (options[i].val), ls);
 144         }
 145       ls = scm_cons (SCM_PACK (options[i].name), ls);
 146       ans = scm_cons (ls, ans);
 147     }
 148   return ans;
 149 }
 150
 151
 152 /* Alters options according to the given option setting 'args'.  The value of
 153  * args is known to be a list, but it is not known whether the list is a well
 154  * formed option setting, i. e. if for every non-boolean option a value is
 155  * given.  For this reason, the function applies all changes to a copy of the
 156  * original setting in memory.  Only if 'args' was successfully processed,
 157  * the new setting will overwrite the old one.  */
 158 static void
 159 change_option_setting (SCM args, scm_t_option options[], unsigned int n, const char *s)
 160 {
 161   unsigned int i;
 162   SCM locally_protected_args = args;
 163   SCM malloc_obj = scm_malloc_obj (n * sizeof (scm_t_bits));
 164   scm_t_bits *flags = (scm_t_bits *) SCM_MALLOCDATA (malloc_obj);
 165
 166   for (i = 0; i != n; ++i)
 167     {
 168       if (options[i].type == SCM_OPTION_BOOLEAN)
 169         flags[i] = 0;
 170       else
 171         flags[i] = options[i].val;
 172     }
 173
 174   while (!SCM_NULL_OR_NIL_P (args))
 175     {
 176       SCM name = SCM_CAR (args);
 177       int found = 0;
 178
 179       for (i = 0; i != n && !found; ++i)
 180         {
 181           if (scm_is_eq (name, SCM_PACK (options[i].name)))
 182             {
 183               switch (options[i].type)
 184                 {
 185                 case SCM_OPTION_BOOLEAN:
 186                   flags[i] = 1;
 187                   break;
 188                 case SCM_OPTION_INTEGER:
 189                   args = SCM_CDR (args);
 190                   SCM_ASSERT (SCM_CONSP (args), args, SCM_ARG1, s);
 191                   flags[i] = scm_to_size_t (SCM_CAR (args));
 192                   break;
 193                 case SCM_OPTION_SCM:
 194                   args = SCM_CDR (args);
 195                   SCM_ASSERT (SCM_CONSP (args), args, SCM_ARG1, s);
 196                   flags[i] = SCM_UNPACK (SCM_CAR (args));
 197                   break;
 198                 }
 199               found = 1;
 200             }
 201         }
 202
 203       if (!found)
 204         scm_misc_error (s, "Unknown option name: ~S", scm_list_1 (name));
 205
 206       args = SCM_CDR (args);
 207     }
 208
 209   for (i = 0; i != n; ++i)
 210     {
 211       if (options[i].type == SCM_OPTION_SCM)
 212         {
 213           SCM old = SCM_PACK (options[i].val);
 214           SCM new = SCM_PACK (flags[i]);
 215           if (!SCM_IMP (old))
 216             protected_objects = scm_delq1_x (old, protected_objects);
 217           if (!SCM_IMP (new))
 218             protected_objects = scm_cons (new, protected_objects);
 219         }
 220       options[i].val = flags[i];
 221     }
 222
 223   scm_remember_upto_here_2 (locally_protected_args, malloc_obj);
 224 }
 225
 226
 227 SCM
 228 scm_options (SCM args, scm_t_option options[], unsigned int n, const char *s)
 229 {
 230   if (SCM_UNBNDP (args))
 231     return get_option_setting (options, n);
 232   else if (!SCM_NULL_OR_NIL_P (args) && !SCM_CONSP (args))
 233     /* Dirk:FIXME:: This criterion should be improved.  IMO it is better to
 234      * demand that args is #t if documentation should be shown than to say
 235      * that every argument except a list will print out documentation.  */
 236     return get_documented_option_setting (options, n);
 237   else
 238     {
 239       SCM old_setting;
 240       SCM_ASSERT (scm_is_true (scm_list_p (args)), args, 1, s);
 241       old_setting = get_option_setting (options, n);
 242       change_option_setting (args, options, n, s);
 243       return old_setting;
 244     }
 245 }
 246
 247
 248 void
 249 scm_init_opts (SCM (*func) (SCM), scm_t_option options[], unsigned int n)
 250 {
 251   unsigned int i;
 252
 253   for (i = 0; i != n; ++i)
 254     {
 255       SCM name = scm_str2symbol (options[i].name);
 256       options[i].name = (char *) SCM_UNPACK (name);
 257       scm_permanent_object (name);
 258     }
 259   func (SCM_UNDEFINED);
 260 }
 261
 262
 263 void
 264 scm_init_options ()
 265 {
 266   scm_gc_register_root (&protected_objects);
 267
 268 #include "libguile/options.x"
 269 }
 270
 271 /*
 272   Local Variables:
 273   c-file-style: "gnu"
 274   End:
 275 */