Commit | Line | Data |
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d4719ab8 | 1 | /* Copyright (C) 1995,1996,1997,1998,1999,2000, 2001, 2002 Free Software Foundation, Inc. |
0f2d19dd JB |
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 | |
82892bed JB |
15 | * the Free Software Foundation, Inc., 59 Temple Place, Suite 330, |
16 | * Boston, MA 02111-1307 USA | |
0f2d19dd JB |
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. | |
82892bed | 40 | * If you do not wish that, delete this exception notice. */ |
1bbd0b84 | 41 | |
1bbd0b84 | 42 | |
0f2d19dd JB |
43 | \f |
44 | ||
783e7774 | 45 | #include <string.h> |
a0599745 MD |
46 | #include "libguile/_scm.h" |
47 | #include "libguile/stackchk.h" | |
48 | #include "libguile/dynwind.h" | |
49 | #include "libguile/eval.h" | |
50 | #include "libguile/smob.h" | |
51 | #include "libguile/pairs.h" | |
52 | #include "libguile/throw.h" | |
53 | #include "libguile/fluids.h" | |
54 | #include "libguile/ports.h" | |
55 | ||
56 | #include "libguile/root.h" | |
0f2d19dd JB |
57 | \f |
58 | ||
59 | SCM scm_sys_protects[SCM_NUM_PROTECTS]; | |
d564d753 | 60 | |
92c2555f | 61 | scm_t_bits scm_tc16_root; |
d564d753 MD |
62 | |
63 | #ifndef USE_THREADS | |
64 | struct scm_root_state *scm_root; | |
65 | #endif | |
0f2d19dd JB |
66 | |
67 | \f | |
68 | ||
d564d753 | 69 | static SCM |
e841c3e0 | 70 | root_mark (SCM root) |
d564d753 MD |
71 | { |
72 | scm_root_state *s = SCM_ROOT_STATE (root); | |
dc53f026 | 73 | |
d564d753 MD |
74 | scm_gc_mark (s->rootcont); |
75 | scm_gc_mark (s->dynwinds); | |
d564d753 MD |
76 | scm_gc_mark (s->progargs); |
77 | scm_gc_mark (s->exitval); | |
78 | scm_gc_mark (s->cur_inp); | |
79 | scm_gc_mark (s->cur_outp); | |
80 | scm_gc_mark (s->cur_errp); | |
903073d5 | 81 | /* No need to gc mark def_loadp */ |
d9dfcf80 | 82 | scm_gc_mark (s->fluids); |
a7d3641d | 83 | scm_gc_mark (s->active_asyncs); |
1ceead47 | 84 | scm_gc_mark (s->signal_asyncs); |
d564d753 MD |
85 | return SCM_ROOT_STATE (root) -> parent; |
86 | } | |
0f2d19dd | 87 | |
d564d753 | 88 | |
d564d753 | 89 | static int |
e81d98ec | 90 | root_print (SCM exp, SCM port, scm_print_state *pstate SCM_UNUSED) |
d564d753 | 91 | { |
b7f3516f | 92 | scm_puts ("#<root ", port); |
d564d753 | 93 | scm_intprint(SCM_SEQ (SCM_ROOT_STATE (exp) -> rootcont), 16, port); |
b7f3516f | 94 | scm_putc('>', port); |
d564d753 MD |
95 | return 1; |
96 | } | |
97 | ||
d564d753 MD |
98 | |
99 | \f | |
100 | ||
101 | SCM | |
1bbd0b84 | 102 | scm_make_root (SCM parent) |
d564d753 MD |
103 | { |
104 | SCM root; | |
105 | scm_root_state *root_state; | |
106 | ||
4c9419ac MV |
107 | root_state = (scm_root_state *) scm_gc_malloc (sizeof (scm_root_state), |
108 | "root state"); | |
0c95b57d | 109 | if (SCM_ROOTP (parent)) |
d564d753 MD |
110 | { |
111 | memcpy (root_state, SCM_ROOT_STATE (parent), sizeof (scm_root_state)); | |
d9dfcf80 | 112 | scm_copy_fluids (root_state); |
d564d753 MD |
113 | root_state->parent = parent; |
114 | } | |
115 | else | |
116 | { | |
117 | root_state->parent = SCM_BOOL_F; | |
4ea1f83d JB |
118 | |
119 | /* Initialize everything right now, in case a GC happens early. */ | |
120 | root_state->rootcont | |
121 | = root_state->dynwinds | |
4ea1f83d JB |
122 | = root_state->progargs |
123 | = root_state->exitval | |
124 | = root_state->cur_inp | |
125 | = root_state->cur_outp | |
126 | = root_state->cur_errp | |
4ea1f83d JB |
127 | = root_state->cur_loadp |
128 | = root_state->fluids | |
4ea1f83d JB |
129 | = root_state->handle |
130 | = root_state->parent | |
131 | = SCM_BOOL_F; | |
d564d753 | 132 | } |
d4719ab8 MV |
133 | |
134 | root_state->active_asyncs = SCM_EOL; | |
1ceead47 | 135 | root_state->signal_asyncs = SCM_EOL; |
8ee25fb9 | 136 | root_state->block_asyncs = 0; |
1ceead47 | 137 | root_state->pending_asyncs = 1; |
d4719ab8 | 138 | |
d564d753 | 139 | SCM_REDEFER_INTS; |
23a62151 | 140 | SCM_NEWSMOB (root, scm_tc16_root, root_state); |
d564d753 MD |
141 | root_state->handle = root; |
142 | SCM_REALLOW_INTS; | |
143 | return root; | |
144 | } | |
145 | ||
1cc91f1b | 146 | /* {call-with-dynamic-root} |
d564d753 MD |
147 | * |
148 | * Suspending the current thread to evaluate a thunk on the | |
149 | * same C stack but under a new root. | |
150 | * | |
1cc91f1b | 151 | * Calls to call-with-dynamic-root return exactly once (unless |
e71575d9 | 152 | * the process is somehow exitted). */ |
d564d753 | 153 | |
650fa1ab JB |
154 | /* Some questions about cwdr: |
155 | ||
156 | Couldn't the body just be a closure? Do we really need to pass | |
157 | args through to it? | |
158 | ||
159 | The semantics are a lot like catch's; in fact, we call | |
160 | scm_internal_catch to take care of that part of things. Wouldn't | |
161 | it be cleaner to say that uncaught throws just disappear into the | |
162 | ether (or print a message to stderr), and let the caller use catch | |
163 | themselves if they want to? | |
164 | ||
165 | -JimB */ | |
166 | ||
d564d753 MD |
167 | #if 0 |
168 | SCM scm_exitval; /* INUM with return value */ | |
169 | #endif | |
c014a02e | 170 | static long n_dynamic_roots = 0; |
d564d753 | 171 | |
650fa1ab | 172 | |
e71575d9 MV |
173 | /* cwdr fills out both of these structures, and then passes a pointer |
174 | to them through scm_internal_catch to the cwdr_body and | |
175 | cwdr_handler functions, to tell them how to behave and to get | |
176 | information back from them. | |
650fa1ab JB |
177 | |
178 | A cwdr is a lot like a catch, except there is no tag (all | |
179 | exceptions are caught), and the body procedure takes the arguments | |
e71575d9 MV |
180 | passed to cwdr as A1 and ARGS. The handler is also special since |
181 | it is not directly run from scm_internal_catch. It is executed | |
182 | outside the new dynamic root. */ | |
650fa1ab JB |
183 | |
184 | struct cwdr_body_data { | |
650fa1ab JB |
185 | /* Arguments to pass to the cwdr body function. */ |
186 | SCM a1, args; | |
187 | ||
188 | /* Scheme procedure to use as body of cwdr. */ | |
189 | SCM body_proc; | |
e71575d9 MV |
190 | }; |
191 | ||
192 | struct cwdr_handler_data { | |
193 | /* Do we need to run the handler? */ | |
194 | int run_handler; | |
f032b8a8 | 195 | |
e71575d9 MV |
196 | /* The tag and args to pass it. */ |
197 | SCM tag, args; | |
650fa1ab JB |
198 | }; |
199 | ||
200 | ||
201 | /* Invoke the body of a cwdr, assuming that the throw handler has | |
202 | already been set up. DATA points to a struct set up by cwdr that | |
816a6f06 JB |
203 | says what proc to call, and what args to apply it to. |
204 | ||
205 | With a little thought, we could replace this with scm_body_thunk, | |
206 | but I don't want to mess with that at the moment. */ | |
650fa1ab | 207 | static SCM |
39752bec | 208 | cwdr_body (void *data) |
650fa1ab JB |
209 | { |
210 | struct cwdr_body_data *c = (struct cwdr_body_data *) data; | |
211 | ||
212 | return scm_apply (c->body_proc, c->a1, c->args); | |
213 | } | |
214 | ||
e71575d9 MV |
215 | /* Record the fact that the body of the cwdr has thrown. Record |
216 | enough information to invoke the handler later when the dynamic | |
217 | root has been deestablished. */ | |
650fa1ab | 218 | |
f032b8a8 | 219 | static SCM |
e71575d9 | 220 | cwdr_handler (void *data, SCM tag, SCM args) |
f032b8a8 | 221 | { |
e71575d9 | 222 | struct cwdr_handler_data *c = (struct cwdr_handler_data *) data; |
f032b8a8 | 223 | |
e71575d9 MV |
224 | c->run_handler = 1; |
225 | c->tag = tag; | |
226 | c->args = args; | |
227 | return SCM_UNSPECIFIED; | |
f032b8a8 | 228 | } |
d564d753 MD |
229 | |
230 | /* This is the basic code for new root creation. | |
231 | * | |
232 | * WARNING! The order of actions in this routine is in many ways | |
233 | * critical. E. g., it is essential that an error doesn't leave Guile | |
650fa1ab | 234 | * in a messed up state. */ |
d564d753 | 235 | |
e71575d9 | 236 | SCM |
92c2555f MV |
237 | scm_internal_cwdr (scm_t_catch_body body, void *body_data, |
238 | scm_t_catch_handler handler, void *handler_data, | |
e71575d9 | 239 | SCM_STACKITEM *stack_start) |
d564d753 MD |
240 | { |
241 | int old_ints_disabled = scm_ints_disabled; | |
8938d022 | 242 | SCM old_rootcont, old_winds; |
e71575d9 | 243 | struct cwdr_handler_data my_handler_data; |
d564d753 MD |
244 | SCM answer; |
245 | ||
e71575d9 | 246 | /* Create a fresh root continuation. */ |
d564d753 MD |
247 | { |
248 | SCM new_rootcont; | |
5f144b10 | 249 | |
d564d753 | 250 | SCM_REDEFER_INTS; |
5f144b10 | 251 | { |
4c9419ac MV |
252 | scm_t_contregs *contregs = scm_gc_malloc (sizeof (scm_t_contregs), |
253 | "continuation"); | |
5f144b10 GH |
254 | |
255 | contregs->num_stack_items = 0; | |
256 | contregs->dynenv = SCM_EOL; | |
257 | contregs->base = stack_start; | |
258 | contregs->seq = ++n_dynamic_roots; | |
259 | contregs->throw_value = SCM_BOOL_F; | |
d564d753 | 260 | #ifdef DEBUG_EXTENSIONS |
5f144b10 | 261 | contregs->dframe = 0; |
d564d753 | 262 | #endif |
5f144b10 GH |
263 | SCM_NEWSMOB (new_rootcont, scm_tc16_continuation, contregs); |
264 | } | |
8938d022 MD |
265 | old_rootcont = scm_rootcont; |
266 | scm_rootcont = new_rootcont; | |
d564d753 MD |
267 | SCM_REALLOW_INTS; |
268 | } | |
269 | ||
8938d022 MD |
270 | /* Exit caller's dynamic state. |
271 | */ | |
272 | old_winds = scm_dynwinds; | |
273 | scm_dowinds (SCM_EOL, scm_ilength (scm_dynwinds)); | |
d564d753 | 274 | #ifdef DEBUG_EXTENSIONS |
308277cb | 275 | SCM_DFRAME (old_rootcont) = scm_last_debug_frame; |
8938d022 | 276 | scm_last_debug_frame = 0; |
d564d753 | 277 | #endif |
650fa1ab | 278 | |
e71575d9 MV |
279 | { |
280 | my_handler_data.run_handler = 0; | |
816a6f06 | 281 | answer = scm_internal_catch (SCM_BOOL_T, |
e71575d9 MV |
282 | body, body_data, |
283 | cwdr_handler, &my_handler_data); | |
650fa1ab | 284 | } |
e71575d9 | 285 | |
d564d753 MD |
286 | scm_dowinds (old_winds, - scm_ilength (old_winds)); |
287 | SCM_REDEFER_INTS; | |
d564d753 | 288 | #ifdef DEBUG_EXTENSIONS |
308277cb | 289 | scm_last_debug_frame = SCM_DFRAME (old_rootcont); |
d564d753 | 290 | #endif |
308277cb | 291 | scm_rootcont = old_rootcont; |
d564d753 MD |
292 | SCM_REALLOW_INTS; |
293 | scm_ints_disabled = old_ints_disabled; | |
e71575d9 MV |
294 | |
295 | /* Now run the real handler iff the body did a throw. */ | |
296 | if (my_handler_data.run_handler) | |
297 | return handler (handler_data, my_handler_data.tag, my_handler_data.args); | |
298 | else | |
299 | return answer; | |
d564d753 MD |
300 | } |
301 | ||
e71575d9 MV |
302 | /* The original CWDR for invoking Scheme code with a Scheme handler. */ |
303 | ||
304 | static SCM | |
305 | cwdr (SCM proc, SCM a1, SCM args, SCM handler, SCM_STACKITEM *stack_start) | |
306 | { | |
307 | struct cwdr_body_data c; | |
308 | ||
309 | c.a1 = a1; | |
310 | c.args = args; | |
311 | c.body_proc = proc; | |
312 | ||
313 | return scm_internal_cwdr (cwdr_body, &c, | |
314 | scm_handle_by_proc, &handler, | |
315 | stack_start); | |
316 | } | |
d564d753 | 317 | |
3b3b36dd | 318 | SCM_DEFINE (scm_call_with_dynamic_root, "call-with-dynamic-root", 2, 0, 0, |
1bbd0b84 | 319 | (SCM thunk, SCM handler), |
1bee0e70 | 320 | "Evaluate @code{(thunk)} in a new dynamic context, returning its value.\n\n" |
b380b885 MD |
321 | "If an error occurs during evaluation, apply @var{handler} to the\n" |
322 | "arguments to the throw, just as @code{throw} would. If this happens,\n" | |
323 | "@var{handler} is called outside the scope of the new root -- it is\n" | |
324 | "called in the same dynamic context in which\n" | |
325 | "@code{call-with-dynamic-root} was evaluated.\n\n" | |
326 | "If @var{thunk} captures a continuation, the continuation is rooted at\n" | |
327 | "the call to @var{thunk}. In particular, the call to\n" | |
328 | "@code{call-with-dynamic-root} is not captured. Therefore,\n" | |
329 | "@code{call-with-dynamic-root} always returns at most one time.\n\n" | |
330 | "Before calling @var{thunk}, the dynamic-wind chain is un-wound back to\n" | |
331 | "the root and a new chain started for @var{thunk}. Therefore, this call\n" | |
332 | "may not do what you expect:\n\n" | |
1e6808ea | 333 | "@lisp\n" |
b380b885 MD |
334 | ";; Almost certainly a bug:\n" |
335 | "(with-output-to-port\n" | |
336 | " some-port\n\n" | |
337 | " (lambda ()\n" | |
338 | " (call-with-dynamic-root\n" | |
339 | " (lambda ()\n" | |
340 | " (display 'fnord)\n" | |
341 | " (newline))\n" | |
342 | " (lambda (errcode) errcode))))\n" | |
1e6808ea | 343 | "@end lisp\n\n" |
2a2a730b | 344 | "The problem is, on what port will @samp{fnord} be displayed? You\n" |
b380b885 MD |
345 | "might expect that because of the @code{with-output-to-port} that\n" |
346 | "it will be displayed on the port bound to @code{some-port}. But it\n" | |
347 | "probably won't -- before evaluating the thunk, dynamic winds are\n" | |
348 | "unwound, including those created by @code{with-output-to-port}.\n" | |
349 | "So, the standard output port will have been re-set to its default value\n" | |
350 | "before @code{display} is evaluated.\n\n" | |
351 | "(This function was added to Guile mostly to help calls to functions in C\n" | |
352 | "libraries that can not tolerate non-local exits or calls that return\n" | |
353 | "multiple times. If such functions call back to the interpreter, it should\n" | |
354 | "be under a new dynamic root.)") | |
1bbd0b84 | 355 | #define FUNC_NAME s_scm_call_with_dynamic_root |
d564d753 MD |
356 | { |
357 | SCM_STACKITEM stack_place; | |
8938d022 | 358 | return cwdr (thunk, SCM_EOL, SCM_EOL, handler, &stack_place); |
d564d753 | 359 | } |
1bbd0b84 | 360 | #undef FUNC_NAME |
d564d753 | 361 | |
3b3b36dd | 362 | SCM_DEFINE (scm_dynamic_root, "dynamic-root", 0, 0, 0, |
1bbd0b84 | 363 | (), |
b380b885 MD |
364 | "Return an object representing the current dynamic root.\n\n" |
365 | "These objects are only useful for comparison using @code{eq?}.\n" | |
366 | "They are currently represented as numbers, but your code should\n" | |
367 | "in no way depend on this.") | |
1bbd0b84 | 368 | #define FUNC_NAME s_scm_dynamic_root |
d564d753 MD |
369 | { |
370 | return scm_ulong2num (SCM_SEQ (scm_root->rootcont)); | |
371 | } | |
1bbd0b84 | 372 | #undef FUNC_NAME |
d564d753 | 373 | |
d564d753 | 374 | SCM |
1bbd0b84 | 375 | scm_apply_with_dynamic_root (SCM proc, SCM a1, SCM args, SCM handler) |
d564d753 MD |
376 | { |
377 | SCM_STACKITEM stack_place; | |
8938d022 | 378 | return cwdr (proc, a1, args, handler, &stack_place); |
d564d753 | 379 | } |
0f2d19dd JB |
380 | |
381 | \f | |
382 | ||
d564d753 MD |
383 | void |
384 | scm_init_root () | |
385 | { | |
cc4feeca | 386 | scm_tc16_root = scm_make_smob_type ("root", sizeof (struct scm_root_state)); |
e841c3e0 KN |
387 | scm_set_smob_mark (scm_tc16_root, root_mark); |
388 | scm_set_smob_print (scm_tc16_root, root_print); | |
cc4feeca | 389 | |
a0599745 | 390 | #include "libguile/root.x" |
d564d753 | 391 | } |
89e00824 ML |
392 | |
393 | /* | |
394 | Local Variables: | |
395 | c-file-style: "gnu" | |
396 | End: | |
397 | */ |