Commit | Line | Data |
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d691ac20 | 1 | /* Copyright (C) 1995,1996,1998,2000,2001,2004, 2006, 2008, 2009, 2010, 2011, 2012, 2013 Free Software Foundation, Inc. |
0f2d19dd | 2 | * |
73be1d9e | 3 | * This library is free software; you can redistribute it and/or |
53befeb7 NJ |
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. | |
0f2d19dd | 7 | * |
53befeb7 NJ |
8 | * This library is distributed in the hope that it will be useful, but |
9 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
73be1d9e MV |
10 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
11 | * Lesser General Public License for more details. | |
0f2d19dd | 12 | * |
73be1d9e MV |
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 | |
53befeb7 NJ |
15 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
16 | * 02110-1301 USA | |
73be1d9e | 17 | */ |
1bbd0b84 | 18 | |
1bbd0b84 | 19 | |
0f2d19dd | 20 | \f |
dbb605f5 LC |
21 | #ifdef HAVE_CONFIG_H |
22 | # include <config.h> | |
23 | #endif | |
0f2d19dd | 24 | |
bbd43f03 RB |
25 | #include "libguile/_scm.h" |
26 | ||
9ede013f | 27 | #include <assert.h> |
13070bd3 | 28 | #include <string.h> |
8b7f0bb3 | 29 | #include <stdio.h> |
13070bd3 | 30 | |
8b7f0bb3 | 31 | #include "libguile/async.h" |
d0f6ceb8 | 32 | #include "libguile/debug.h" |
a0599745 MD |
33 | #include "libguile/root.h" |
34 | #include "libguile/stackchk.h" | |
5f144b10 GH |
35 | #include "libguile/smob.h" |
36 | #include "libguile/ports.h" | |
9ede013f | 37 | #include "libguile/dynstack.h" |
9de87eea | 38 | #include "libguile/eval.h" |
bfffd258 | 39 | #include "libguile/vm.h" |
1d1cae0e | 40 | #include "libguile/instructions.h" |
5f144b10 | 41 | |
db4b4ca6 | 42 | #include "libguile/validate.h" |
a0599745 | 43 | #include "libguile/continuations.h" |
01c8a3dd | 44 | |
0f2d19dd JB |
45 | \f |
46 | ||
1d1cae0e AW |
47 | static scm_t_bits tc16_continuation; |
48 | #define SCM_CONTREGSP(x) SCM_TYP16_PREDICATE (tc16_continuation, x) | |
49 | ||
50 | #define SCM_CONTREGS(x) ((scm_t_contregs *) SCM_SMOB_DATA_1 (x)) | |
51 | ||
52 | #define SCM_CONTINUATION_LENGTH(x) (SCM_CONTREGS (x)->num_stack_items) | |
53 | #define SCM_SET_CONTINUATION_LENGTH(x, n)\ | |
54 | (SCM_CONTREGS (x)->num_stack_items = (n)) | |
55 | #define SCM_JMPBUF(x) ((SCM_CONTREGS (x))->jmpbuf) | |
1d1cae0e AW |
56 | #define SCM_CONTINUATION_ROOT(x) ((SCM_CONTREGS (x))->root) |
57 | #define SCM_DFRAME(x) ((SCM_CONTREGS (x))->dframe) | |
58 | ||
59 | \f | |
60 | ||
d691ac20 AW |
61 | /* scm_i_make_continuation will return a procedure whose code will |
62 | reinstate the continuation. Here, as in gsubr.c, we define the form | |
63 | of that trampoline function. | |
0f2d19dd JB |
64 | */ |
65 | ||
d691ac20 AW |
66 | static const scm_t_uint32 continuation_stub_code[] = |
67 | { | |
68 | SCM_PACK_RTL_24 (scm_rtl_op_continuation_call, 0) | |
69 | }; | |
1d1cae0e | 70 | |
d691ac20 AW |
71 | /* Before Scheme's call/cc is compiled, eval.c will use this hand-coded |
72 | call/cc. */ | |
babfc7b2 | 73 | |
d691ac20 AW |
74 | static const scm_t_uint32 call_cc_code[] = |
75 | { | |
76 | SCM_PACK_RTL_24 (scm_rtl_op_assert_nargs_ee, 2), | |
77 | SCM_PACK_RTL_24 (scm_rtl_op_call_cc, 0) | |
78 | }; | |
babfc7b2 | 79 | |
1d1cae0e AW |
80 | static SCM |
81 | make_continuation_trampoline (SCM contregs) | |
82 | { | |
d691ac20 AW |
83 | SCM ret; |
84 | scm_t_bits nfree = 1; | |
85 | scm_t_bits flags = SCM_F_PROGRAM_IS_CONTINUATION; | |
86 | ||
87 | ret = scm_words (scm_tc7_rtl_program | (nfree << 16) | flags, nfree + 2); | |
88 | SCM_SET_CELL_WORD_1 (ret, continuation_stub_code); | |
89 | SCM_RTL_PROGRAM_FREE_VARIABLE_SET (ret, 0, contregs); | |
1d1cae0e AW |
90 | |
91 | return ret; | |
92 | } | |
93 | ||
94 | ||
95 | /* {Continuations} | |
96 | */ | |
0f2d19dd | 97 | |
01c8a3dd | 98 | |
e841c3e0 | 99 | static int |
e81d98ec | 100 | continuation_print (SCM obj, SCM port, scm_print_state *state SCM_UNUSED) |
5f144b10 | 101 | { |
92c2555f | 102 | scm_t_contregs *continuation = SCM_CONTREGS (obj); |
5f144b10 | 103 | |
0607ebbf | 104 | scm_puts_unlocked ("#<continuation ", port); |
5f144b10 | 105 | scm_intprint (continuation->num_stack_items, 10, port); |
0607ebbf | 106 | scm_puts_unlocked (" @ ", port); |
0236bc68 | 107 | scm_uintprint (SCM_SMOB_DATA_1 (obj), 16, port); |
0607ebbf | 108 | scm_putc_unlocked ('>', port); |
5f144b10 GH |
109 | return 1; |
110 | } | |
1cc91f1b | 111 | |
2acdd822 AW |
112 | /* James Clark came up with this neat one instruction fix for |
113 | * continuations on the SPARC. It flushes the register windows so | |
114 | * that all the state of the process is contained in the stack. | |
115 | */ | |
116 | ||
117 | #if defined (sparc) || defined (__sparc__) || defined (__sparc) | |
118 | # define SCM_FLUSH_REGISTER_WINDOWS asm("ta 3") | |
119 | #else | |
120 | # define SCM_FLUSH_REGISTER_WINDOWS /* empty */ | |
121 | #endif | |
122 | ||
5f144b10 | 123 | /* this may return more than once: the first time with the escape |
d8873dfe AW |
124 | procedure, then subsequently with SCM_UNDEFINED (the vals already having been |
125 | placed on the VM stack). */ | |
997659f8 | 126 | #define FUNC_NAME "scm_i_make_continuation" |
0f2d19dd | 127 | SCM |
269479e3 | 128 | scm_i_make_continuation (int *first, SCM vm, SCM vm_cont) |
0f2d19dd | 129 | { |
9de87eea MV |
130 | scm_i_thread *thread = SCM_I_CURRENT_THREAD; |
131 | SCM cont; | |
92c2555f | 132 | scm_t_contregs *continuation; |
c014a02e | 133 | long stack_size; |
01c8a3dd | 134 | SCM_STACKITEM * src; |
0f2d19dd | 135 | |
0f2d19dd | 136 | SCM_FLUSH_REGISTER_WINDOWS; |
9de87eea | 137 | stack_size = scm_stack_size (thread->continuation_base); |
4c9419ac MV |
138 | continuation = scm_gc_malloc (sizeof (scm_t_contregs) |
139 | + (stack_size - 1) * sizeof (SCM_STACKITEM), | |
140 | "continuation"); | |
5f144b10 | 141 | continuation->num_stack_items = stack_size; |
9de87eea | 142 | continuation->root = thread->continuation_root; |
9de87eea | 143 | src = thread->continuation_base; |
4ccb2cd2 | 144 | #if ! SCM_STACK_GROWS_UP |
5f144b10 GH |
145 | src -= stack_size; |
146 | #endif | |
5c5c27dc | 147 | continuation->offset = continuation->stack - src; |
5f144b10 | 148 | memcpy (continuation->stack, src, sizeof (SCM_STACKITEM) * stack_size); |
269479e3 AW |
149 | continuation->vm = vm; |
150 | continuation->vm_cont = vm_cont; | |
5f144b10 | 151 | |
1d1cae0e | 152 | SCM_NEWSMOB (cont, tc16_continuation, continuation); |
79824460 | 153 | |
a4dbe1ac | 154 | *first = !SCM_I_SETJMP (continuation->jmpbuf); |
346e4402 | 155 | if (*first) |
193297d8 | 156 | { |
346e4402 | 157 | #ifdef __ia64__ |
9a5fa6e9 | 158 | continuation->backing_store_size = |
346e4402 | 159 | (char *) scm_ia64_ar_bsp(&continuation->jmpbuf.ctx) |
9a5fa6e9 | 160 | - |
346e4402 | 161 | (char *) thread->register_backing_store_base; |
193297d8 RB |
162 | continuation->backing_store = NULL; |
163 | continuation->backing_store = | |
4c9419ac MV |
164 | scm_gc_malloc (continuation->backing_store_size, |
165 | "continuation backing store"); | |
193297d8 | 166 | memcpy (continuation->backing_store, |
346e4402 | 167 | (void *) thread->register_backing_store_base, |
193297d8 | 168 | continuation->backing_store_size); |
346e4402 | 169 | #endif /* __ia64__ */ |
1d1cae0e | 170 | return make_continuation_trampoline (cont); |
193297d8 RB |
171 | } |
172 | else | |
d8873dfe | 173 | return SCM_UNDEFINED; |
0f2d19dd | 174 | } |
5f144b10 | 175 | #undef FUNC_NAME |
0f2d19dd | 176 | |
babfc7b2 AW |
177 | SCM |
178 | scm_i_call_with_current_continuation (SCM proc) | |
179 | { | |
180 | static SCM call_cc = SCM_BOOL_F; | |
181 | ||
182 | if (scm_is_false (call_cc)) | |
d691ac20 | 183 | call_cc = scm_i_make_rtl_program (call_cc_code); |
babfc7b2 AW |
184 | |
185 | return scm_call_1 (call_cc, proc); | |
186 | } | |
187 | ||
1d1cae0e AW |
188 | SCM |
189 | scm_i_continuation_to_frame (SCM continuation) | |
190 | { | |
191 | SCM contregs; | |
192 | scm_t_contregs *cont; | |
193 | ||
d691ac20 | 194 | contregs = SCM_RTL_PROGRAM_FREE_VARIABLE_REF (continuation, 0); |
1d1cae0e AW |
195 | cont = SCM_CONTREGS (contregs); |
196 | ||
269479e3 | 197 | if (scm_is_true (cont->vm_cont)) |
1d1cae0e | 198 | { |
269479e3 AW |
199 | struct scm_vm_cont *data = SCM_VM_CONT_DATA (cont->vm_cont); |
200 | return scm_c_make_frame (cont->vm_cont, | |
1d1cae0e AW |
201 | data->fp + data->reloc, |
202 | data->sp + data->reloc, | |
d8873dfe | 203 | data->ra, |
1d1cae0e AW |
204 | data->reloc); |
205 | } | |
206 | else | |
207 | return SCM_BOOL_F; | |
208 | } | |
209 | ||
d8873dfe AW |
210 | SCM |
211 | scm_i_contregs_vm (SCM contregs) | |
212 | { | |
213 | return SCM_CONTREGS (contregs)->vm; | |
214 | } | |
215 | ||
216 | SCM | |
217 | scm_i_contregs_vm_cont (SCM contregs) | |
218 | { | |
219 | return SCM_CONTREGS (contregs)->vm_cont; | |
220 | } | |
221 | ||
1d1cae0e AW |
222 | |
223 | /* {Apply} | |
224 | */ | |
d3c6aef9 MV |
225 | |
226 | /* Invoking a continuation proceeds as follows: | |
227 | * | |
228 | * - the stack is made large enough for the called continuation | |
229 | * - the old windchain is unwound down to the branching point | |
230 | * - the continuation stack is copied into place | |
231 | * - the windchain is rewound up to the continuation's context | |
232 | * - the continuation is invoked via longjmp (or setcontext) | |
233 | * | |
234 | * This order is important so that unwind and rewind handlers are run | |
235 | * with their correct stack. | |
236 | */ | |
237 | ||
d8873dfe | 238 | static void scm_dynthrow (SCM); |
01c8a3dd DH |
239 | |
240 | /* Grow the stack by a fixed amount to provide space to copy in the | |
241 | * continuation. Possibly this function has to be called several times | |
242 | * recursively before enough space is available. Make sure the compiler does | |
243 | * not optimize the growth array away by storing it's address into a global | |
244 | * variable. | |
245 | */ | |
246 | ||
8c93b597 | 247 | static scm_t_bits scm_i_dummy; |
1cc91f1b | 248 | |
0f2d19dd | 249 | static void |
d8873dfe | 250 | grow_stack (SCM cont) |
01c8a3dd | 251 | { |
92c2555f | 252 | scm_t_bits growth[100]; |
01c8a3dd | 253 | |
92c2555f | 254 | scm_i_dummy = (scm_t_bits) growth; |
d8873dfe | 255 | scm_dynthrow (cont); |
0f2d19dd | 256 | } |
0f2d19dd | 257 | |
1cc91f1b | 258 | |
01c8a3dd DH |
259 | /* Copy the continuation stack into the current stack. Calling functions from |
260 | * within this function is safe, since only stack frames below this function's | |
261 | * own frame are overwritten. Thus, memcpy can be used for best performance. | |
262 | */ | |
d3c6aef9 | 263 | |
d3c6aef9 | 264 | static void |
d8873dfe | 265 | copy_stack_and_call (scm_t_contregs *continuation, |
5f144b10 | 266 | SCM_STACKITEM * dst) |
0f2d19dd | 267 | { |
9ede013f AW |
268 | scm_t_dynstack *dynstack; |
269 | scm_t_bits *joint; | |
270 | scm_i_thread *thread = SCM_I_CURRENT_THREAD; | |
271 | ||
272 | dynstack = SCM_VM_CONT_DATA (continuation->vm_cont)->dynstack; | |
273 | ||
274 | joint = scm_dynstack_unwind_fork (&thread->dynstack, dynstack); | |
275 | ||
276 | memcpy (dst, continuation->stack, | |
277 | sizeof (SCM_STACKITEM) * continuation->num_stack_items); | |
278 | #ifdef __ia64__ | |
279 | thread->pending_rbs_continuation = continuation; | |
280 | #endif | |
d3c6aef9 | 281 | |
9ede013f | 282 | scm_dynstack_wind (&thread->dynstack, joint); |
01c8a3dd | 283 | |
a4dbe1ac | 284 | SCM_I_LONGJMP (continuation->jmpbuf, 1); |
01c8a3dd DH |
285 | } |
286 | ||
346e4402 NJ |
287 | #ifdef __ia64__ |
288 | void | |
a4dbe1ac | 289 | scm_ia64_longjmp (scm_i_jmp_buf *JB, int VAL) |
346e4402 NJ |
290 | { |
291 | scm_i_thread *t = SCM_I_CURRENT_THREAD; | |
292 | ||
293 | if (t->pending_rbs_continuation) | |
294 | { | |
295 | memcpy (t->register_backing_store_base, | |
296 | t->pending_rbs_continuation->backing_store, | |
297 | t->pending_rbs_continuation->backing_store_size); | |
298 | t->pending_rbs_continuation = NULL; | |
299 | } | |
300 | setcontext (&JB->ctx); | |
301 | } | |
302 | #endif | |
303 | ||
01c8a3dd DH |
304 | /* Call grow_stack until the stack space is large enough, then, as the current |
305 | * stack frame might get overwritten, let copy_stack_and_call perform the | |
306 | * actual copying and continuation calling. | |
307 | */ | |
308 | static void | |
d8873dfe | 309 | scm_dynthrow (SCM cont) |
01c8a3dd | 310 | { |
9de87eea | 311 | scm_i_thread *thread = SCM_I_CURRENT_THREAD; |
92c2555f | 312 | scm_t_contregs *continuation = SCM_CONTREGS (cont); |
9de87eea | 313 | SCM_STACKITEM *dst = thread->continuation_base; |
01c8a3dd DH |
314 | SCM_STACKITEM stack_top_element; |
315 | ||
87f30eda | 316 | if (thread->critical_section_level) |
8b7f0bb3 MV |
317 | { |
318 | fprintf (stderr, "continuation invoked from within critical section.\n"); | |
319 | abort (); | |
320 | } | |
321 | ||
4ccb2cd2 | 322 | #if SCM_STACK_GROWS_UP |
5afcf08b | 323 | if (dst + continuation->num_stack_items >= &stack_top_element) |
d8873dfe | 324 | grow_stack (cont); |
0f2d19dd | 325 | #else |
5f144b10 | 326 | dst -= continuation->num_stack_items; |
c8a1bdc4 | 327 | if (dst <= &stack_top_element) |
d8873dfe | 328 | grow_stack (cont); |
0f2d19dd | 329 | #endif /* def SCM_STACK_GROWS_UP */ |
01c8a3dd | 330 | |
5f144b10 | 331 | SCM_FLUSH_REGISTER_WINDOWS; |
d8873dfe | 332 | copy_stack_and_call (continuation, dst); |
0f2d19dd JB |
333 | } |
334 | ||
db4b4ca6 | 335 | |
1d1cae0e | 336 | void |
d8873dfe | 337 | scm_i_check_continuation (SCM cont) |
0f2d19dd | 338 | { |
9de87eea | 339 | scm_i_thread *thread = SCM_I_CURRENT_THREAD; |
92c2555f | 340 | scm_t_contregs *continuation = SCM_CONTREGS (cont); |
5f144b10 | 341 | |
d223c3fc | 342 | if (!scm_is_eq (continuation->root, thread->continuation_root)) |
1d1cae0e AW |
343 | scm_misc_error |
344 | ("%continuation-call", | |
345 | "invoking continuation would cross continuation barrier: ~A", | |
346 | scm_list_1 (cont)); | |
d8873dfe AW |
347 | } |
348 | ||
349 | void | |
350 | scm_i_reinstate_continuation (SCM cont) | |
351 | { | |
352 | scm_dynthrow (cont); | |
0f2d19dd | 353 | } |
0f2d19dd | 354 | |
9de87eea MV |
355 | SCM |
356 | scm_i_with_continuation_barrier (scm_t_catch_body body, | |
357 | void *body_data, | |
358 | scm_t_catch_handler handler, | |
43e01b1e NJ |
359 | void *handler_data, |
360 | scm_t_catch_handler pre_unwind_handler, | |
361 | void *pre_unwind_handler_data) | |
9de87eea MV |
362 | { |
363 | SCM_STACKITEM stack_item; | |
364 | scm_i_thread *thread = SCM_I_CURRENT_THREAD; | |
365 | SCM old_controot; | |
366 | SCM_STACKITEM *old_contbase; | |
9de87eea MV |
367 | SCM result; |
368 | ||
369 | /* Establish a fresh continuation root. | |
370 | */ | |
371 | old_controot = thread->continuation_root; | |
372 | old_contbase = thread->continuation_base; | |
9de87eea MV |
373 | thread->continuation_root = scm_cons (thread->handle, old_controot); |
374 | thread->continuation_base = &stack_item; | |
9de87eea MV |
375 | |
376 | /* Call FUNC inside a catch all. This is now guaranteed to return | |
377 | directly and exactly once. | |
378 | */ | |
43e01b1e NJ |
379 | result = scm_c_catch (SCM_BOOL_T, |
380 | body, body_data, | |
381 | handler, handler_data, | |
382 | pre_unwind_handler, pre_unwind_handler_data); | |
9de87eea MV |
383 | |
384 | /* Return to old continuation root. | |
385 | */ | |
9de87eea MV |
386 | thread->continuation_base = old_contbase; |
387 | thread->continuation_root = old_controot; | |
388 | ||
389 | return result; | |
390 | } | |
391 | ||
e309f3bf AW |
392 | \f |
393 | ||
394 | static int | |
395 | should_print_backtrace (SCM tag, SCM stack) | |
396 | { | |
397 | return SCM_BACKTRACE_P | |
398 | && scm_is_true (stack) | |
399 | && scm_initialized_p | |
400 | /* It's generally not useful to print backtraces for errors reading | |
401 | or expanding code in these fallback catch statements. */ | |
402 | && !scm_is_eq (tag, scm_from_latin1_symbol ("read-error")) | |
403 | && !scm_is_eq (tag, scm_from_latin1_symbol ("syntax-error")); | |
404 | } | |
405 | ||
406 | static void | |
407 | print_exception_and_backtrace (SCM port, SCM tag, SCM args) | |
408 | { | |
409 | SCM stack, frame; | |
410 | ||
411 | /* We get here via a throw to a catch-all. In that case there is the | |
412 | throw frame active, and this catch closure, so narrow by two | |
413 | frames. */ | |
414 | stack = scm_make_stack (SCM_BOOL_T, scm_list_1 (scm_from_int (2))); | |
415 | frame = scm_is_true (stack) ? scm_stack_ref (stack, SCM_INUM0) : SCM_BOOL_F; | |
416 | ||
417 | if (should_print_backtrace (tag, stack)) | |
418 | { | |
0607ebbf | 419 | scm_puts_unlocked ("Backtrace:\n", port); |
e309f3bf AW |
420 | scm_display_backtrace_with_highlights (stack, port, |
421 | SCM_BOOL_F, SCM_BOOL_F, | |
422 | SCM_EOL); | |
423 | scm_newline (port); | |
424 | } | |
425 | ||
426 | scm_print_exception (port, frame, tag, args); | |
427 | } | |
428 | ||
429 | \f | |
430 | ||
9de87eea MV |
431 | struct c_data { |
432 | void *(*func) (void *); | |
433 | void *data; | |
434 | void *result; | |
435 | }; | |
436 | ||
437 | static SCM | |
438 | c_body (void *d) | |
439 | { | |
440 | struct c_data *data = (struct c_data *)d; | |
441 | data->result = data->func (data->data); | |
442 | return SCM_UNSPECIFIED; | |
443 | } | |
444 | ||
445 | static SCM | |
446 | c_handler (void *d, SCM tag, SCM args) | |
447 | { | |
e309f3bf AW |
448 | struct c_data *data; |
449 | ||
450 | /* If TAG is `quit', exit() the process. */ | |
451 | if (scm_is_eq (tag, scm_from_latin1_symbol ("quit"))) | |
452 | exit (scm_exit_status (args)); | |
453 | ||
454 | data = (struct c_data *)d; | |
9de87eea MV |
455 | data->result = NULL; |
456 | return SCM_UNSPECIFIED; | |
457 | } | |
458 | ||
e309f3bf AW |
459 | static SCM |
460 | pre_unwind_handler (void *error_port, SCM tag, SCM args) | |
461 | { | |
462 | /* Print the exception unless TAG is `quit'. */ | |
463 | if (!scm_is_eq (tag, scm_from_latin1_symbol ("quit"))) | |
21041372 | 464 | print_exception_and_backtrace (SCM_PACK_POINTER (error_port), tag, args); |
e309f3bf AW |
465 | |
466 | return SCM_UNSPECIFIED; | |
467 | } | |
468 | ||
9de87eea MV |
469 | void * |
470 | scm_c_with_continuation_barrier (void *(*func) (void *), void *data) | |
471 | { | |
472 | struct c_data c_data; | |
473 | c_data.func = func; | |
474 | c_data.data = data; | |
475 | scm_i_with_continuation_barrier (c_body, &c_data, | |
43e01b1e | 476 | c_handler, &c_data, |
e309f3bf | 477 | pre_unwind_handler, |
21041372 | 478 | SCM_UNPACK_POINTER (scm_current_error_port ())); |
9de87eea MV |
479 | return c_data.result; |
480 | } | |
481 | ||
482 | struct scm_data { | |
483 | SCM proc; | |
484 | }; | |
485 | ||
486 | static SCM | |
487 | scm_body (void *d) | |
488 | { | |
489 | struct scm_data *data = (struct scm_data *)d; | |
490 | return scm_call_0 (data->proc); | |
491 | } | |
492 | ||
493 | static SCM | |
494 | scm_handler (void *d, SCM tag, SCM args) | |
495 | { | |
e309f3bf AW |
496 | /* Print a message. Note that if TAG is `quit', this will exit() the |
497 | process. */ | |
498 | scm_handle_by_message_noexit (NULL, tag, args); | |
499 | ||
9de87eea MV |
500 | return SCM_BOOL_F; |
501 | } | |
502 | ||
503 | SCM_DEFINE (scm_with_continuation_barrier, "with-continuation-barrier", 1,0,0, | |
504 | (SCM proc), | |
69d2000d MV |
505 | "Call @var{proc} and return its result. Do not allow the invocation of\n" |
506 | "continuations that would leave or enter the dynamic extent of the call\n" | |
507 | "to @code{with-continuation-barrier}. Such an attempt causes an error\n" | |
508 | "to be signaled.\n" | |
509 | "\n" | |
510 | "Throws (such as errors) that are not caught from within @var{proc} are\n" | |
511 | "caught by @code{with-continuation-barrier}. In that case, a short\n" | |
512 | "message is printed to the current error port and @code{#f} is returned.\n" | |
513 | "\n" | |
514 | "Thus, @code{with-continuation-barrier} returns exactly once.\n") | |
9de87eea MV |
515 | #define FUNC_NAME s_scm_with_continuation_barrier |
516 | { | |
517 | struct scm_data scm_data; | |
518 | scm_data.proc = proc; | |
519 | return scm_i_with_continuation_barrier (scm_body, &scm_data, | |
43e01b1e | 520 | scm_handler, &scm_data, |
e309f3bf | 521 | pre_unwind_handler, |
21041372 | 522 | SCM_UNPACK_POINTER (scm_current_error_port ())); |
9de87eea MV |
523 | } |
524 | #undef FUNC_NAME | |
db4b4ca6 | 525 | |
0f2d19dd JB |
526 | void |
527 | scm_init_continuations () | |
0f2d19dd | 528 | { |
1d1cae0e AW |
529 | tc16_continuation = scm_make_smob_type ("continuation", 0); |
530 | scm_set_smob_print (tc16_continuation, continuation_print); | |
a0599745 | 531 | #include "libguile/continuations.x" |
0f2d19dd JB |
532 | } |
533 | ||
89e00824 ML |
534 | /* |
535 | Local Variables: | |
536 | c-file-style: "gnu" | |
537 | End: | |
538 | */ |