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f2c9fcb0 | 1 | /* Copyright (C) 1995,1996,1997,1998, 1999, 2000 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 GB |
41 | |
42 | /* Software engineering face-lift by Greg J. Badros, 11-Dec-1999, | |
43 | gjb@cs.washington.edu, http://www.cs.washington.edu/homes/gjb */ | |
44 | ||
0f2d19dd JB |
45 | \f |
46 | ||
783e7774 | 47 | #include <string.h> |
a0599745 MD |
48 | #include "libguile/_scm.h" |
49 | #include "libguile/stackchk.h" | |
50 | #include "libguile/dynwind.h" | |
51 | #include "libguile/eval.h" | |
52 | #include "libguile/smob.h" | |
53 | #include "libguile/pairs.h" | |
54 | #include "libguile/throw.h" | |
55 | #include "libguile/fluids.h" | |
56 | #include "libguile/ports.h" | |
57 | ||
58 | #include "libguile/root.h" | |
0f2d19dd JB |
59 | \f |
60 | ||
61 | SCM scm_sys_protects[SCM_NUM_PROTECTS]; | |
d564d753 | 62 | |
e841c3e0 | 63 | scm_bits_t scm_tc16_root; |
d564d753 MD |
64 | |
65 | #ifndef USE_THREADS | |
66 | struct scm_root_state *scm_root; | |
67 | #endif | |
0f2d19dd JB |
68 | |
69 | \f | |
70 | ||
d564d753 | 71 | static SCM |
e841c3e0 | 72 | root_mark (SCM root) |
d564d753 MD |
73 | { |
74 | scm_root_state *s = SCM_ROOT_STATE (root); | |
dc53f026 | 75 | |
d564d753 MD |
76 | scm_gc_mark (s->rootcont); |
77 | scm_gc_mark (s->dynwinds); | |
78 | scm_gc_mark (s->continuation_stack); | |
79 | scm_gc_mark (s->continuation_stack_ptr); | |
80 | scm_gc_mark (s->progargs); | |
81 | scm_gc_mark (s->exitval); | |
82 | scm_gc_mark (s->cur_inp); | |
83 | scm_gc_mark (s->cur_outp); | |
84 | scm_gc_mark (s->cur_errp); | |
85 | scm_gc_mark (s->def_inp); | |
86 | scm_gc_mark (s->def_outp); | |
87 | scm_gc_mark (s->def_errp); | |
903073d5 | 88 | /* No need to gc mark def_loadp */ |
d9dfcf80 | 89 | scm_gc_mark (s->fluids); |
d564d753 MD |
90 | return SCM_ROOT_STATE (root) -> parent; |
91 | } | |
0f2d19dd | 92 | |
d564d753 | 93 | |
d564d753 | 94 | static int |
e841c3e0 | 95 | root_print (SCM exp, SCM port, scm_print_state *pstate) |
d564d753 | 96 | { |
b7f3516f | 97 | scm_puts ("#<root ", port); |
d564d753 | 98 | scm_intprint(SCM_SEQ (SCM_ROOT_STATE (exp) -> rootcont), 16, port); |
b7f3516f | 99 | scm_putc('>', port); |
d564d753 MD |
100 | return 1; |
101 | } | |
102 | ||
d564d753 MD |
103 | |
104 | \f | |
105 | ||
106 | SCM | |
1bbd0b84 | 107 | scm_make_root (SCM parent) |
d564d753 MD |
108 | { |
109 | SCM root; | |
110 | scm_root_state *root_state; | |
111 | ||
112 | root_state = (scm_root_state *) scm_must_malloc (sizeof (scm_root_state), | |
113 | "scm_make_root"); | |
0c95b57d | 114 | if (SCM_ROOTP (parent)) |
d564d753 MD |
115 | { |
116 | memcpy (root_state, SCM_ROOT_STATE (parent), sizeof (scm_root_state)); | |
d9dfcf80 | 117 | scm_copy_fluids (root_state); |
d564d753 MD |
118 | root_state->parent = parent; |
119 | } | |
120 | else | |
121 | { | |
122 | root_state->parent = SCM_BOOL_F; | |
4ea1f83d JB |
123 | |
124 | /* Initialize everything right now, in case a GC happens early. */ | |
125 | root_state->rootcont | |
126 | = root_state->dynwinds | |
127 | = root_state->continuation_stack | |
128 | = root_state->continuation_stack_ptr | |
129 | = root_state->progargs | |
130 | = root_state->exitval | |
131 | = root_state->cur_inp | |
132 | = root_state->cur_outp | |
133 | = root_state->cur_errp | |
134 | = root_state->def_inp | |
135 | = root_state->def_outp | |
136 | = root_state->def_errp | |
137 | = root_state->cur_loadp | |
138 | = root_state->fluids | |
4ea1f83d JB |
139 | = root_state->handle |
140 | = root_state->parent | |
141 | = SCM_BOOL_F; | |
d564d753 | 142 | } |
d564d753 | 143 | SCM_REDEFER_INTS; |
23a62151 | 144 | SCM_NEWSMOB (root, scm_tc16_root, root_state); |
d564d753 MD |
145 | root_state->handle = root; |
146 | SCM_REALLOW_INTS; | |
147 | return root; | |
148 | } | |
149 | ||
1cc91f1b | 150 | /* {call-with-dynamic-root} |
d564d753 MD |
151 | * |
152 | * Suspending the current thread to evaluate a thunk on the | |
153 | * same C stack but under a new root. | |
154 | * | |
1cc91f1b | 155 | * Calls to call-with-dynamic-root return exactly once (unless |
e71575d9 | 156 | * the process is somehow exitted). */ |
d564d753 | 157 | |
650fa1ab JB |
158 | /* Some questions about cwdr: |
159 | ||
160 | Couldn't the body just be a closure? Do we really need to pass | |
161 | args through to it? | |
162 | ||
163 | The semantics are a lot like catch's; in fact, we call | |
164 | scm_internal_catch to take care of that part of things. Wouldn't | |
165 | it be cleaner to say that uncaught throws just disappear into the | |
166 | ether (or print a message to stderr), and let the caller use catch | |
167 | themselves if they want to? | |
168 | ||
169 | -JimB */ | |
170 | ||
d564d753 MD |
171 | #if 0 |
172 | SCM scm_exitval; /* INUM with return value */ | |
173 | #endif | |
1be6b49c | 174 | static scm_bits_t n_dynamic_roots = 0; |
d564d753 | 175 | |
650fa1ab | 176 | |
e71575d9 MV |
177 | /* cwdr fills out both of these structures, and then passes a pointer |
178 | to them through scm_internal_catch to the cwdr_body and | |
179 | cwdr_handler functions, to tell them how to behave and to get | |
180 | information back from them. | |
650fa1ab JB |
181 | |
182 | A cwdr is a lot like a catch, except there is no tag (all | |
183 | exceptions are caught), and the body procedure takes the arguments | |
e71575d9 MV |
184 | passed to cwdr as A1 and ARGS. The handler is also special since |
185 | it is not directly run from scm_internal_catch. It is executed | |
186 | outside the new dynamic root. */ | |
650fa1ab JB |
187 | |
188 | struct cwdr_body_data { | |
650fa1ab JB |
189 | /* Arguments to pass to the cwdr body function. */ |
190 | SCM a1, args; | |
191 | ||
192 | /* Scheme procedure to use as body of cwdr. */ | |
193 | SCM body_proc; | |
e71575d9 MV |
194 | }; |
195 | ||
196 | struct cwdr_handler_data { | |
197 | /* Do we need to run the handler? */ | |
198 | int run_handler; | |
f032b8a8 | 199 | |
e71575d9 MV |
200 | /* The tag and args to pass it. */ |
201 | SCM tag, args; | |
650fa1ab JB |
202 | }; |
203 | ||
204 | ||
205 | /* Invoke the body of a cwdr, assuming that the throw handler has | |
206 | already been set up. DATA points to a struct set up by cwdr that | |
816a6f06 JB |
207 | says what proc to call, and what args to apply it to. |
208 | ||
209 | With a little thought, we could replace this with scm_body_thunk, | |
210 | but I don't want to mess with that at the moment. */ | |
650fa1ab | 211 | static SCM |
39752bec | 212 | cwdr_body (void *data) |
650fa1ab JB |
213 | { |
214 | struct cwdr_body_data *c = (struct cwdr_body_data *) data; | |
215 | ||
216 | return scm_apply (c->body_proc, c->a1, c->args); | |
217 | } | |
218 | ||
e71575d9 MV |
219 | /* Record the fact that the body of the cwdr has thrown. Record |
220 | enough information to invoke the handler later when the dynamic | |
221 | root has been deestablished. */ | |
650fa1ab | 222 | |
f032b8a8 | 223 | static SCM |
e71575d9 | 224 | cwdr_handler (void *data, SCM tag, SCM args) |
f032b8a8 | 225 | { |
e71575d9 | 226 | struct cwdr_handler_data *c = (struct cwdr_handler_data *) data; |
f032b8a8 | 227 | |
e71575d9 MV |
228 | c->run_handler = 1; |
229 | c->tag = tag; | |
230 | c->args = args; | |
231 | return SCM_UNSPECIFIED; | |
f032b8a8 | 232 | } |
d564d753 MD |
233 | |
234 | /* This is the basic code for new root creation. | |
235 | * | |
236 | * WARNING! The order of actions in this routine is in many ways | |
237 | * critical. E. g., it is essential that an error doesn't leave Guile | |
650fa1ab | 238 | * in a messed up state. */ |
d564d753 | 239 | |
e71575d9 MV |
240 | SCM |
241 | scm_internal_cwdr (scm_catch_body_t body, void *body_data, | |
242 | scm_catch_handler_t handler, void *handler_data, | |
243 | SCM_STACKITEM *stack_start) | |
d564d753 MD |
244 | { |
245 | int old_ints_disabled = scm_ints_disabled; | |
8938d022 | 246 | SCM old_rootcont, old_winds; |
e71575d9 | 247 | struct cwdr_handler_data my_handler_data; |
d564d753 MD |
248 | SCM answer; |
249 | ||
e71575d9 | 250 | /* Create a fresh root continuation. */ |
d564d753 MD |
251 | { |
252 | SCM new_rootcont; | |
5f144b10 | 253 | |
d564d753 | 254 | SCM_REDEFER_INTS; |
5f144b10 | 255 | { |
1be6b49c | 256 | scm_contregs_t *contregs = scm_must_malloc (sizeof (scm_contregs_t), |
5f144b10 GH |
257 | "inferior root continuation"); |
258 | ||
259 | contregs->num_stack_items = 0; | |
260 | contregs->dynenv = SCM_EOL; | |
261 | contregs->base = stack_start; | |
262 | contregs->seq = ++n_dynamic_roots; | |
263 | contregs->throw_value = SCM_BOOL_F; | |
d564d753 | 264 | #ifdef DEBUG_EXTENSIONS |
5f144b10 | 265 | contregs->dframe = 0; |
d564d753 | 266 | #endif |
5f144b10 GH |
267 | SCM_NEWSMOB (new_rootcont, scm_tc16_continuation, contregs); |
268 | } | |
8938d022 MD |
269 | old_rootcont = scm_rootcont; |
270 | scm_rootcont = new_rootcont; | |
d564d753 MD |
271 | SCM_REALLOW_INTS; |
272 | } | |
273 | ||
8938d022 MD |
274 | /* Exit caller's dynamic state. |
275 | */ | |
276 | old_winds = scm_dynwinds; | |
277 | scm_dowinds (SCM_EOL, scm_ilength (scm_dynwinds)); | |
d564d753 | 278 | #ifdef DEBUG_EXTENSIONS |
308277cb | 279 | SCM_DFRAME (old_rootcont) = scm_last_debug_frame; |
8938d022 | 280 | scm_last_debug_frame = 0; |
d564d753 | 281 | #endif |
650fa1ab | 282 | |
e71575d9 MV |
283 | { |
284 | my_handler_data.run_handler = 0; | |
816a6f06 | 285 | answer = scm_internal_catch (SCM_BOOL_T, |
e71575d9 MV |
286 | body, body_data, |
287 | cwdr_handler, &my_handler_data); | |
650fa1ab | 288 | } |
e71575d9 | 289 | |
d564d753 MD |
290 | scm_dowinds (old_winds, - scm_ilength (old_winds)); |
291 | SCM_REDEFER_INTS; | |
d564d753 | 292 | #ifdef DEBUG_EXTENSIONS |
308277cb | 293 | scm_last_debug_frame = SCM_DFRAME (old_rootcont); |
d564d753 | 294 | #endif |
308277cb | 295 | scm_rootcont = old_rootcont; |
d564d753 MD |
296 | SCM_REALLOW_INTS; |
297 | scm_ints_disabled = old_ints_disabled; | |
e71575d9 MV |
298 | |
299 | /* Now run the real handler iff the body did a throw. */ | |
300 | if (my_handler_data.run_handler) | |
301 | return handler (handler_data, my_handler_data.tag, my_handler_data.args); | |
302 | else | |
303 | return answer; | |
d564d753 MD |
304 | } |
305 | ||
e71575d9 MV |
306 | /* The original CWDR for invoking Scheme code with a Scheme handler. */ |
307 | ||
308 | static SCM | |
309 | cwdr (SCM proc, SCM a1, SCM args, SCM handler, SCM_STACKITEM *stack_start) | |
310 | { | |
311 | struct cwdr_body_data c; | |
312 | ||
313 | c.a1 = a1; | |
314 | c.args = args; | |
315 | c.body_proc = proc; | |
316 | ||
317 | return scm_internal_cwdr (cwdr_body, &c, | |
318 | scm_handle_by_proc, &handler, | |
319 | stack_start); | |
320 | } | |
d564d753 | 321 | |
3b3b36dd | 322 | SCM_DEFINE (scm_call_with_dynamic_root, "call-with-dynamic-root", 2, 0, 0, |
1bbd0b84 | 323 | (SCM thunk, SCM handler), |
1bee0e70 | 324 | "Evaluate @code{(thunk)} in a new dynamic context, returning its value.\n\n" |
b380b885 MD |
325 | "If an error occurs during evaluation, apply @var{handler} to the\n" |
326 | "arguments to the throw, just as @code{throw} would. If this happens,\n" | |
327 | "@var{handler} is called outside the scope of the new root -- it is\n" | |
328 | "called in the same dynamic context in which\n" | |
329 | "@code{call-with-dynamic-root} was evaluated.\n\n" | |
330 | "If @var{thunk} captures a continuation, the continuation is rooted at\n" | |
331 | "the call to @var{thunk}. In particular, the call to\n" | |
332 | "@code{call-with-dynamic-root} is not captured. Therefore,\n" | |
333 | "@code{call-with-dynamic-root} always returns at most one time.\n\n" | |
334 | "Before calling @var{thunk}, the dynamic-wind chain is un-wound back to\n" | |
335 | "the root and a new chain started for @var{thunk}. Therefore, this call\n" | |
336 | "may not do what you expect:\n\n" | |
1e6808ea | 337 | "@lisp\n" |
b380b885 MD |
338 | ";; Almost certainly a bug:\n" |
339 | "(with-output-to-port\n" | |
340 | " some-port\n\n" | |
341 | " (lambda ()\n" | |
342 | " (call-with-dynamic-root\n" | |
343 | " (lambda ()\n" | |
344 | " (display 'fnord)\n" | |
345 | " (newline))\n" | |
346 | " (lambda (errcode) errcode))))\n" | |
1e6808ea | 347 | "@end lisp\n\n" |
2a2a730b | 348 | "The problem is, on what port will @samp{fnord} be displayed? You\n" |
b380b885 MD |
349 | "might expect that because of the @code{with-output-to-port} that\n" |
350 | "it will be displayed on the port bound to @code{some-port}. But it\n" | |
351 | "probably won't -- before evaluating the thunk, dynamic winds are\n" | |
352 | "unwound, including those created by @code{with-output-to-port}.\n" | |
353 | "So, the standard output port will have been re-set to its default value\n" | |
354 | "before @code{display} is evaluated.\n\n" | |
355 | "(This function was added to Guile mostly to help calls to functions in C\n" | |
356 | "libraries that can not tolerate non-local exits or calls that return\n" | |
357 | "multiple times. If such functions call back to the interpreter, it should\n" | |
358 | "be under a new dynamic root.)") | |
1bbd0b84 | 359 | #define FUNC_NAME s_scm_call_with_dynamic_root |
d564d753 MD |
360 | { |
361 | SCM_STACKITEM stack_place; | |
8938d022 | 362 | return cwdr (thunk, SCM_EOL, SCM_EOL, handler, &stack_place); |
d564d753 | 363 | } |
1bbd0b84 | 364 | #undef FUNC_NAME |
d564d753 | 365 | |
3b3b36dd | 366 | SCM_DEFINE (scm_dynamic_root, "dynamic-root", 0, 0, 0, |
1bbd0b84 | 367 | (), |
b380b885 MD |
368 | "Return an object representing the current dynamic root.\n\n" |
369 | "These objects are only useful for comparison using @code{eq?}.\n" | |
370 | "They are currently represented as numbers, but your code should\n" | |
371 | "in no way depend on this.") | |
1bbd0b84 | 372 | #define FUNC_NAME s_scm_dynamic_root |
d564d753 MD |
373 | { |
374 | return scm_ulong2num (SCM_SEQ (scm_root->rootcont)); | |
375 | } | |
1bbd0b84 | 376 | #undef FUNC_NAME |
d564d753 | 377 | |
d564d753 | 378 | SCM |
1bbd0b84 | 379 | scm_apply_with_dynamic_root (SCM proc, SCM a1, SCM args, SCM handler) |
d564d753 MD |
380 | { |
381 | SCM_STACKITEM stack_place; | |
8938d022 | 382 | return cwdr (proc, a1, args, handler, &stack_place); |
d564d753 | 383 | } |
0f2d19dd JB |
384 | |
385 | \f | |
386 | ||
cc4feeca DH |
387 | #if (SCM_DEBUG_DEPRECATED == 0) |
388 | ||
0f2d19dd JB |
389 | /* Call thunk(closure) underneath a top-level error handler. |
390 | * If an error occurs, pass the exitval through err_filter and return it. | |
391 | * If no error occurs, return the value of thunk. | |
392 | */ | |
393 | ||
0f2d19dd JB |
394 | #ifdef _UNICOS |
395 | typedef int setjmp_type; | |
396 | #else | |
397 | typedef long setjmp_type; | |
398 | #endif | |
399 | ||
400 | ||
0f2d19dd | 401 | SCM |
1bbd0b84 | 402 | scm_call_catching_errors (SCM (*thunk)(), SCM (*err_filter)(), void *closure) |
0f2d19dd JB |
403 | { |
404 | SCM answer; | |
405 | setjmp_type i; | |
faa6b3df | 406 | #ifdef DEBUG_EXTENSIONS |
8938d022 | 407 | SCM_DFRAME (scm_rootcont) = scm_last_debug_frame; |
faa6b3df | 408 | #endif |
0f2d19dd | 409 | i = setjmp (SCM_JMPBUF (scm_rootcont)); |
faa6b3df | 410 | scm_stack_checking_enabled_p = SCM_STACK_CHECKING_P; |
0f2d19dd JB |
411 | if (!i) |
412 | { | |
413 | scm_gc_heap_lock = 0; | |
414 | answer = thunk (closure); | |
415 | } | |
416 | else | |
417 | { | |
418 | scm_gc_heap_lock = 1; | |
419 | answer = err_filter (scm_exitval, closure); | |
420 | } | |
421 | return answer; | |
422 | } | |
423 | ||
cc4feeca DH |
424 | #endif /* SCM_DEBUG_DEPRECATED == 0 */ |
425 | ||
426 | ||
d564d753 MD |
427 | void |
428 | scm_init_root () | |
429 | { | |
cc4feeca | 430 | scm_tc16_root = scm_make_smob_type ("root", sizeof (struct scm_root_state)); |
e841c3e0 KN |
431 | scm_set_smob_mark (scm_tc16_root, root_mark); |
432 | scm_set_smob_print (scm_tc16_root, root_print); | |
cc4feeca | 433 | |
8dc9439f | 434 | #ifndef SCM_MAGIC_SNARFER |
a0599745 | 435 | #include "libguile/root.x" |
8dc9439f | 436 | #endif |
d564d753 | 437 | } |
89e00824 ML |
438 | |
439 | /* | |
440 | Local Variables: | |
441 | c-file-style: "gnu" | |
442 | End: | |
443 | */ |