Merge branch 'boehm-demers-weiser-gc' into bdw-gc-static-alloc
[bpt/guile.git] / libguile / options.c
1 /* Copyright (C) 1995,1996,1998,2000,2001, 2006, 2008 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 License
5 * as published by the Free Software Foundation; either version 3 of
6 * the License, or (at your option) any later version.
7 *
8 * This library is distributed in the hope that it will be useful, but
9 * 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
16 * 02110-1301 USA
17 */
18
19 \f
20 #ifdef HAVE_CONFIG_H
21 # include <config.h>
22 #endif
23
24 #include "libguile/_scm.h"
25 #include "libguile/mallocs.h"
26 #include "libguile/strings.h"
27 #include "libguile/lang.h"
28
29 #include "libguile/options.h"
30 \f
31
32 /* {Run-time options}
33 *
34 * This is the basic interface for low-level configuration of the
35 * Guile library. It is used for configuring the reader, evaluator,
36 * printer and debugger.
37 *
38 * Motivation:
39 *
40 * 1. Altering option settings can have side effects.
41 * 2. Option values can be stored in native format.
42 * (Important for efficiency in, e. g., the evaluator.)
43 * 3. Doesn't use up name space.
44 * 4. Options can be naturally grouped => ease of use.
45 */
46
47 /* scm_options is the core of all options interface procedures.
48 *
49 * Some definitions:
50 *
51 * Run time options in Guile are arranged in groups. Each group
52 * affects a certain aspect of the behaviour of the library.
53 *
54 * An "options interface procedure" manages one group of options. It
55 * can be used to check or set options, or to get documentation for
56 * all options of a group. The options interface procedure is not
57 * intended to be called directly by the user. The user should
58 * instead call
59 *
60 * (<group>-options)
61 * (<group>-options 'help)
62 * (<group>-options 'full)
63 *
64 * to display current option settings (The second version also
65 * displays documentation. The third version also displays
66 * information about programmer's options.), and
67 *
68 * (<group>-enable '<option-symbol>)
69 * (<group>-disable '<option-symbol>)
70 * (<group>-set! <option-symbol> <value>)
71 * (<group>-options <option setting>)
72 *
73 * to alter the state of an option (The last version sets all
74 * options according to <option setting>.) where <group> is the name
75 * of the option group.
76 *
77 * An "option setting" represents the state of all low-level options
78 * managed by one options interface procedure. It is a list of
79 * single symbols and symbols followed by a value.
80 *
81 * For boolean options, the presence of the symbol of that option in
82 * the option setting indicates a true value. If the symbol isn't a
83 * member of the option setting this represents a false value.
84 *
85 * Other options are represented by a symbol followed by the value.
86 *
87 * If scm_options is called without arguments, the current option
88 * setting is returned. If the argument is an option setting, options
89 * are altered and the old setting is returned. If the argument isn't
90 * a list, a list of sublists is returned, where each sublist contains
91 * option name, value and documentation string.
92 */
93
94 SCM_SYMBOL (scm_yes_sym, "yes");
95 SCM_SYMBOL (scm_no_sym, "no");
96
97 static SCM protected_objects = SCM_EOL;
98
99 /* Return a list of the current option setting. The format of an
100 * option setting is described in the above documentation. */
101 static SCM
102 get_option_setting (const scm_t_option options[])
103 {
104 unsigned int i;
105 SCM ls = SCM_EOL;
106 for (i = 0; options[i].name; ++i)
107 {
108 switch (options[i].type)
109 {
110 case SCM_OPTION_BOOLEAN:
111 if (options[i].val)
112 ls = scm_cons (SCM_PACK (options[i].name), ls);
113 break;
114 case SCM_OPTION_INTEGER:
115 ls = scm_cons (scm_from_unsigned_integer (options[i].val), ls);
116 ls = scm_cons (SCM_PACK (options[i].name), ls);
117 break;
118 case SCM_OPTION_SCM:
119 ls = scm_cons (SCM_PACK (options[i].val), ls);
120 ls = scm_cons (SCM_PACK (options[i].name), ls);
121 }
122 }
123 return ls;
124 }
125
126
127 /* Return a list of sublists, where each sublist contains option name, value
128 * and documentation string. */
129 static SCM
130 get_documented_option_setting (const scm_t_option options[])
131 {
132 SCM ans = SCM_EOL;
133 unsigned int i;
134
135 for (i = 0; options[i].name; ++i)
136 {
137 SCM ls = scm_cons (scm_from_locale_string (options[i].doc), SCM_EOL);
138 switch (options[i].type)
139 {
140 case SCM_OPTION_BOOLEAN:
141 ls = scm_cons (options[i].val ? scm_yes_sym : scm_no_sym, ls);
142 break;
143 case SCM_OPTION_INTEGER:
144 ls = scm_cons (scm_from_unsigned_integer (options[i].val), ls);
145 break;
146 case SCM_OPTION_SCM:
147 ls = scm_cons (SCM_PACK (options[i].val), ls);
148 }
149 ls = scm_cons (SCM_PACK (options[i].name), ls);
150 ans = scm_cons (ls, ans);
151 }
152 return ans;
153 }
154
155
156 static int
157 options_length (scm_t_option options[])
158 {
159 unsigned int i = 0;
160 for (; options[i].name != NULL; ++i)
161 ;
162
163 return i;
164 }
165
166 /* Alters options according to the given option setting 'args'. The value of
167 * args is known to be a list, but it is not known whether the list is a well
168 * formed option setting, i. e. if for every non-boolean option a value is
169 * given. For this reason, the function applies all changes to a copy of the
170 * original setting in memory. Only if 'args' was successfully processed,
171 * the new setting will overwrite the old one.
172 *
173 * If DRY_RUN is set, don't change anything. This is useful for trying out an option
174 * before entering a critical section.
175 */
176 static void
177 change_option_setting (SCM args, scm_t_option options[], const char *s,
178 int dry_run)
179 {
180 unsigned int i;
181 SCM locally_protected_args = args;
182 SCM malloc_obj = scm_malloc_obj (options_length (options) * sizeof (scm_t_bits));
183 scm_t_bits *flags = (scm_t_bits *) SCM_MALLOCDATA (malloc_obj);
184
185 for (i = 0; options[i].name; ++i)
186 {
187 if (options[i].type == SCM_OPTION_BOOLEAN)
188 flags[i] = 0;
189 else
190 flags[i] = options[i].val;
191 }
192
193 while (!SCM_NULL_OR_NIL_P (args))
194 {
195 SCM name = SCM_CAR (args);
196 int found = 0;
197
198 for (i = 0; options[i].name && !found; ++i)
199 {
200 if (scm_is_eq (name, SCM_PACK (options[i].name)))
201 {
202 switch (options[i].type)
203 {
204 case SCM_OPTION_BOOLEAN:
205 flags[i] = 1;
206 break;
207 case SCM_OPTION_INTEGER:
208 args = SCM_CDR (args);
209 flags[i] = scm_to_size_t (scm_car (args));
210 break;
211 case SCM_OPTION_SCM:
212 args = SCM_CDR (args);
213 flags[i] = SCM_UNPACK (scm_car (args));
214 break;
215 }
216 found = 1;
217 }
218 }
219
220 if (!found)
221 scm_misc_error (s, "Unknown option name: ~S", scm_list_1 (name));
222
223 args = SCM_CDR (args);
224 }
225
226 if (dry_run)
227 return;
228
229 for (i = 0; options[i].name; ++i)
230 {
231 if (options[i].type == SCM_OPTION_SCM)
232 {
233 SCM old = SCM_PACK (options[i].val);
234 SCM new = SCM_PACK (flags[i]);
235 if (!SCM_IMP (old))
236 protected_objects = scm_delq1_x (old, protected_objects);
237 if (!SCM_IMP (new))
238 protected_objects = scm_cons (new, protected_objects);
239 }
240 options[i].val = flags[i];
241 }
242
243 scm_remember_upto_here_2 (locally_protected_args, malloc_obj);
244 }
245
246
247 SCM
248 scm_options (SCM args, scm_t_option options[], const char *s)
249 {
250 return scm_options_try (args, options, s, 0);
251 }
252
253 SCM
254 scm_options_try (SCM args, scm_t_option options[], const char *s,
255 int dry_run)
256 {
257 if (SCM_UNBNDP (args))
258 return get_option_setting (options);
259 else if (!SCM_NULL_OR_NIL_P (args) && !scm_is_pair (args))
260 /* Dirk:FIXME:: This criterion should be improved. IMO it is better to
261 * demand that args is #t if documentation should be shown than to say
262 * that every argument except a list will print out documentation. */
263 return get_documented_option_setting (options);
264 else
265 {
266 SCM old_setting;
267 SCM_ASSERT (scm_is_true (scm_list_p (args)), args, 1, s);
268 old_setting = get_option_setting (options);
269 change_option_setting (args, options, s, dry_run);
270 return old_setting;
271 }
272 }
273
274
275 void
276 scm_init_opts (SCM (*func) (SCM), scm_t_option options[])
277 {
278 unsigned int i;
279
280 for (i = 0; options[i].name; ++i)
281 {
282 SCM name = scm_from_locale_symbol (options[i].name);
283 options[i].name = (char *) SCM_UNPACK (name);
284 scm_permanent_object (name);
285 }
286 func (SCM_UNDEFINED);
287 }
288
289
290 void
291 scm_init_options ()
292 {
293 scm_gc_register_root (&protected_objects);
294
295 #include "libguile/options.x"
296 }
297
298 /*
299 Local Variables:
300 c-file-style: "gnu"
301 End:
302 */