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
  96 /* Return a list of the current option setting.  The format of an option
  97  * setting is described in the above documentation.  */
  98 static SCM
  99 get_option_setting (const scm_t_option options[], unsigned int n)
 100 {
 101   unsigned int i;
 102   SCM ls = SCM_EOL;
 103   for (i = 0; i != n; ++i)
 104     {
 105       switch (options[i].type)
 106         {
 107         case SCM_OPTION_BOOLEAN:
 108           if (options[i].val)
 109             ls = scm_cons (SCM_PACK (options[i].name), ls);
 110           break;
 111         case SCM_OPTION_INTEGER:
 112           ls = scm_cons (SCM_MAKINUM (options[i].val), ls);
 113           ls = scm_cons (SCM_PACK (options[i].name), ls);
 114           break;
 115         case SCM_OPTION_SCM:
 116           ls = scm_cons (SCM_PACK (options[i].val), ls);
 117           ls = scm_cons (SCM_PACK (options[i].name), ls);
 118         }
 119     }
 120   return ls;
 121 }
 122
 123
 124 /* Return a list of sublists, where each sublist contains option name, value
 125  * and documentation string.  */
 126 static SCM
 127 get_documented_option_setting (const scm_t_option options[], unsigned int n)
 128 {
 129   SCM ans = SCM_EOL;
 130   unsigned int i;
 131
 132   for (i = 0; i != n; ++i)
 133     {
 134       SCM ls = scm_cons (scm_str2string (options[i].doc), SCM_EOL);
 135       switch (options[i].type)
 136         {
 137         case SCM_OPTION_BOOLEAN:
 138           ls = scm_cons (options[i].val ? scm_yes_sym : scm_no_sym, ls);
 139           break;
 140         case SCM_OPTION_INTEGER:
 141           ls = scm_cons (SCM_MAKINUM (options[i].val), ls);
 142           break;
 143         case SCM_OPTION_SCM:
 144           ls = scm_cons (SCM_PACK (options[i].val), ls);
 145         }
 146       ls = scm_cons (SCM_PACK (options[i].name), ls);
 147       ans = scm_cons (ls, ans);
 148     }
 149   return ans;
 150 }
 151
 152
 153 /* Alters options according to the given option setting 'args'.  The value of
 154  * args is known to be a list, but it is not known whether the list is a well
 155  * formed option setting, i. e. if for every non-boolean option a value is
 156  * given.  For this reason, the function applies all changes to a copy of the
 157  * original setting in memory.  Only if 'args' was successfully processed,
 158  * the new setting will overwrite the old one.  */
 159 static void
 160 change_option_setting (SCM args, scm_t_option options[], unsigned int n, const char *s)
 161 {
 162   unsigned int i;
 163   SCM locally_protected_args = args;
 164   SCM malloc_obj = scm_malloc_obj (n * sizeof (scm_t_bits));
 165   scm_t_bits *flags = (scm_t_bits *) SCM_MALLOCDATA (malloc_obj);
 166
 167   for (i = 0; i != n; ++i)
 168     {
 169       if (options[i].type == SCM_OPTION_BOOLEAN)
 170         flags[i] = 0;
 171       else
 172         flags[i] = options[i].val;
 173     }
 174
 175   while (!SCM_NULL_OR_NIL_P (args))
 176     {
 177       SCM name = SCM_CAR (args);
 178       int found = 0;
 179
 180       for (i = 0; i != n && !found; ++i)
 181         {
 182           if (SCM_EQ_P (name, SCM_PACK (options[i].name)))
 183             {
 184               switch (options[i].type)
 185                 {
 186                 case SCM_OPTION_BOOLEAN:
 187                   flags[i] = 1;
 188                   break;
 189                 case SCM_OPTION_INTEGER:
 190                   args = SCM_CDR (args);
 191                   SCM_ASSERT (SCM_CONSP (args), args, SCM_ARG1, s);
 192                   SCM_ASSERT (SCM_INUMP (SCM_CAR (args)), args, SCM_ARG1, s);
 193                   flags[i] = SCM_INUM (SCM_CAR (args));
 194                   break;
 195                 case SCM_OPTION_SCM:
 196                   args = SCM_CDR (args);
 197                   SCM_ASSERT (SCM_CONSP (args), args, SCM_ARG1, s);
 198                   flags[i] = SCM_UNPACK (SCM_CAR (args));
 199                   break;
 200                 }
 201               found = 1;
 202             }
 203         }
 204
 205       if (!found)
 206         scm_misc_error (s, "Unknown option name: ~S", scm_list_1 (name));
 207
 208       args = SCM_CDR (args);
 209     }
 210
 211   for (i = 0; i != n; ++i)
 212     {
 213       if (options[i].type == SCM_OPTION_SCM)
 214         {
 215           SCM old = SCM_PACK (options[i].val);
 216           SCM new = SCM_PACK (flags[i]);
 217           if (!SCM_IMP (old))
 218             protected_objects = scm_delq1_x (old, protected_objects);
 219           if (!SCM_IMP (new))
 220             protected_objects = scm_cons (new, protected_objects);
 221         }
 222       options[i].val = flags[i];
 223     }
 224
 225   scm_remember_upto_here_2 (locally_protected_args, malloc_obj);
 226 }
 227
 228
 229 SCM
 230 scm_options (SCM args, scm_t_option options[], unsigned int n, const char *s)
 231 {
 232   if (SCM_UNBNDP (args))
 233     return get_option_setting (options, n);
 234   else if (!SCM_NULL_OR_NIL_P (args) && !SCM_CONSP (args))
 235     /* Dirk:FIXME:: This criterion should be improved.  IMO it is better to
 236      * demand that args is #t if documentation should be shown than to say
 237      * that every argument except a list will print out documentation.  */
 238     return get_documented_option_setting (options, n);
 239   else
 240     {
 241       SCM old_setting;
 242       SCM_ASSERT (!SCM_FALSEP (scm_list_p (args)), args, 1, s);
 243       old_setting = get_option_setting (options, n);
 244       change_option_setting (args, options, n, s);
 245       return old_setting;
 246     }
 247 }
 248
 249
 250 void
 251 scm_init_opts (SCM (*func) (SCM), scm_t_option options[], unsigned int n)
 252 {
 253   unsigned int i;
 254
 255   for (i = 0; i != n; ++i)
 256     {
 257       SCM name = scm_str2symbol (options[i].name);
 258       options[i].name = (char *) SCM_UNPACK (name);
 259       scm_permanent_object (name);
 260     }
 261   func (SCM_UNDEFINED);
 262 }
 263
 264
 265 void
 266 scm_init_options ()
 267 {
 268   scm_gc_register_root (&protected_objects);
 269
 270 #include "libguile/options.x"
 271 }
 272
 273 /*
 274   Local Variables:
 275   c-file-style: "gnu"
 276   End:
 277 */