Commit | Line | Data |
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d4719ab8 | 1 | /* Copyright (C) 1995,1996,1997,1998,1999,2000, 2001, 2002 Free Software Foundation, Inc. |
0f2d19dd | 2 | * |
73be1d9e MV |
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. | |
0f2d19dd | 7 | * |
73be1d9e MV |
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. | |
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 | |
15 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
16 | */ | |
1bbd0b84 | 17 | |
1bbd0b84 | 18 | |
0f2d19dd JB |
19 | \f |
20 | ||
783e7774 | 21 | #include <string.h> |
a0599745 MD |
22 | #include "libguile/_scm.h" |
23 | #include "libguile/stackchk.h" | |
24 | #include "libguile/dynwind.h" | |
25 | #include "libguile/eval.h" | |
26 | #include "libguile/smob.h" | |
27 | #include "libguile/pairs.h" | |
28 | #include "libguile/throw.h" | |
29 | #include "libguile/fluids.h" | |
30 | #include "libguile/ports.h" | |
31 | ||
32 | #include "libguile/root.h" | |
0f2d19dd JB |
33 | \f |
34 | ||
35 | SCM scm_sys_protects[SCM_NUM_PROTECTS]; | |
d564d753 | 36 | |
92c2555f | 37 | scm_t_bits scm_tc16_root; |
d564d753 | 38 | |
0f2d19dd JB |
39 | \f |
40 | ||
d564d753 | 41 | static SCM |
e841c3e0 | 42 | root_mark (SCM root) |
d564d753 MD |
43 | { |
44 | scm_root_state *s = SCM_ROOT_STATE (root); | |
dc53f026 | 45 | |
d564d753 MD |
46 | scm_gc_mark (s->rootcont); |
47 | scm_gc_mark (s->dynwinds); | |
d564d753 MD |
48 | scm_gc_mark (s->progargs); |
49 | scm_gc_mark (s->exitval); | |
50 | scm_gc_mark (s->cur_inp); | |
51 | scm_gc_mark (s->cur_outp); | |
52 | scm_gc_mark (s->cur_errp); | |
903073d5 | 53 | /* No need to gc mark def_loadp */ |
d9dfcf80 | 54 | scm_gc_mark (s->fluids); |
a7d3641d | 55 | scm_gc_mark (s->active_asyncs); |
1ceead47 | 56 | scm_gc_mark (s->signal_asyncs); |
d564d753 MD |
57 | return SCM_ROOT_STATE (root) -> parent; |
58 | } | |
0f2d19dd | 59 | |
d564d753 | 60 | |
d564d753 | 61 | static int |
e81d98ec | 62 | root_print (SCM exp, SCM port, scm_print_state *pstate SCM_UNUSED) |
d564d753 | 63 | { |
b7f3516f | 64 | scm_puts ("#<root ", port); |
d564d753 | 65 | scm_intprint(SCM_SEQ (SCM_ROOT_STATE (exp) -> rootcont), 16, port); |
b7f3516f | 66 | scm_putc('>', port); |
d564d753 MD |
67 | return 1; |
68 | } | |
69 | ||
d564d753 MD |
70 | |
71 | \f | |
72 | ||
73 | SCM | |
1bbd0b84 | 74 | scm_make_root (SCM parent) |
d564d753 MD |
75 | { |
76 | SCM root; | |
77 | scm_root_state *root_state; | |
78 | ||
4c9419ac MV |
79 | root_state = (scm_root_state *) scm_gc_malloc (sizeof (scm_root_state), |
80 | "root state"); | |
0c95b57d | 81 | if (SCM_ROOTP (parent)) |
d564d753 MD |
82 | { |
83 | memcpy (root_state, SCM_ROOT_STATE (parent), sizeof (scm_root_state)); | |
84 | root_state->parent = parent; | |
85 | } | |
86 | else | |
87 | { | |
88 | root_state->parent = SCM_BOOL_F; | |
4ea1f83d JB |
89 | |
90 | /* Initialize everything right now, in case a GC happens early. */ | |
91 | root_state->rootcont | |
92 | = root_state->dynwinds | |
4ea1f83d JB |
93 | = root_state->progargs |
94 | = root_state->exitval | |
95 | = root_state->cur_inp | |
96 | = root_state->cur_outp | |
97 | = root_state->cur_errp | |
4ea1f83d JB |
98 | = root_state->cur_loadp |
99 | = root_state->fluids | |
4ea1f83d JB |
100 | = root_state->handle |
101 | = root_state->parent | |
102 | = SCM_BOOL_F; | |
d564d753 | 103 | } |
d4719ab8 MV |
104 | |
105 | root_state->active_asyncs = SCM_EOL; | |
1ceead47 | 106 | root_state->signal_asyncs = SCM_EOL; |
8ee25fb9 | 107 | root_state->block_asyncs = 0; |
1ceead47 | 108 | root_state->pending_asyncs = 1; |
d4719ab8 | 109 | |
23a62151 | 110 | SCM_NEWSMOB (root, scm_tc16_root, root_state); |
d564d753 | 111 | root_state->handle = root; |
392d2833 MD |
112 | |
113 | if (SCM_ROOTP (parent)) | |
114 | /* Must be done here so that fluids are GC protected */ | |
115 | scm_copy_fluids (root_state); | |
116 | ||
d564d753 MD |
117 | return root; |
118 | } | |
119 | ||
1cc91f1b | 120 | /* {call-with-dynamic-root} |
d564d753 MD |
121 | * |
122 | * Suspending the current thread to evaluate a thunk on the | |
123 | * same C stack but under a new root. | |
124 | * | |
1cc91f1b | 125 | * Calls to call-with-dynamic-root return exactly once (unless |
e71575d9 | 126 | * the process is somehow exitted). */ |
d564d753 | 127 | |
650fa1ab JB |
128 | /* Some questions about cwdr: |
129 | ||
130 | Couldn't the body just be a closure? Do we really need to pass | |
131 | args through to it? | |
132 | ||
133 | The semantics are a lot like catch's; in fact, we call | |
134 | scm_internal_catch to take care of that part of things. Wouldn't | |
135 | it be cleaner to say that uncaught throws just disappear into the | |
136 | ether (or print a message to stderr), and let the caller use catch | |
137 | themselves if they want to? | |
138 | ||
139 | -JimB */ | |
140 | ||
d564d753 MD |
141 | #if 0 |
142 | SCM scm_exitval; /* INUM with return value */ | |
143 | #endif | |
c014a02e | 144 | static long n_dynamic_roots = 0; |
d564d753 | 145 | |
650fa1ab | 146 | |
e71575d9 MV |
147 | /* cwdr fills out both of these structures, and then passes a pointer |
148 | to them through scm_internal_catch to the cwdr_body and | |
149 | cwdr_handler functions, to tell them how to behave and to get | |
150 | information back from them. | |
650fa1ab JB |
151 | |
152 | A cwdr is a lot like a catch, except there is no tag (all | |
153 | exceptions are caught), and the body procedure takes the arguments | |
e71575d9 MV |
154 | passed to cwdr as A1 and ARGS. The handler is also special since |
155 | it is not directly run from scm_internal_catch. It is executed | |
156 | outside the new dynamic root. */ | |
650fa1ab JB |
157 | |
158 | struct cwdr_body_data { | |
650fa1ab JB |
159 | /* Arguments to pass to the cwdr body function. */ |
160 | SCM a1, args; | |
161 | ||
162 | /* Scheme procedure to use as body of cwdr. */ | |
163 | SCM body_proc; | |
e71575d9 MV |
164 | }; |
165 | ||
166 | struct cwdr_handler_data { | |
167 | /* Do we need to run the handler? */ | |
168 | int run_handler; | |
f032b8a8 | 169 | |
e71575d9 MV |
170 | /* The tag and args to pass it. */ |
171 | SCM tag, args; | |
650fa1ab JB |
172 | }; |
173 | ||
174 | ||
175 | /* Invoke the body of a cwdr, assuming that the throw handler has | |
176 | already been set up. DATA points to a struct set up by cwdr that | |
816a6f06 JB |
177 | says what proc to call, and what args to apply it to. |
178 | ||
179 | With a little thought, we could replace this with scm_body_thunk, | |
180 | but I don't want to mess with that at the moment. */ | |
650fa1ab | 181 | static SCM |
39752bec | 182 | cwdr_body (void *data) |
650fa1ab JB |
183 | { |
184 | struct cwdr_body_data *c = (struct cwdr_body_data *) data; | |
185 | ||
186 | return scm_apply (c->body_proc, c->a1, c->args); | |
187 | } | |
188 | ||
e71575d9 MV |
189 | /* Record the fact that the body of the cwdr has thrown. Record |
190 | enough information to invoke the handler later when the dynamic | |
191 | root has been deestablished. */ | |
650fa1ab | 192 | |
f032b8a8 | 193 | static SCM |
e71575d9 | 194 | cwdr_handler (void *data, SCM tag, SCM args) |
f032b8a8 | 195 | { |
e71575d9 | 196 | struct cwdr_handler_data *c = (struct cwdr_handler_data *) data; |
f032b8a8 | 197 | |
e71575d9 MV |
198 | c->run_handler = 1; |
199 | c->tag = tag; | |
200 | c->args = args; | |
201 | return SCM_UNSPECIFIED; | |
f032b8a8 | 202 | } |
d564d753 MD |
203 | |
204 | /* This is the basic code for new root creation. | |
205 | * | |
206 | * WARNING! The order of actions in this routine is in many ways | |
207 | * critical. E. g., it is essential that an error doesn't leave Guile | |
650fa1ab | 208 | * in a messed up state. */ |
d564d753 | 209 | |
e71575d9 | 210 | SCM |
92c2555f MV |
211 | scm_internal_cwdr (scm_t_catch_body body, void *body_data, |
212 | scm_t_catch_handler handler, void *handler_data, | |
e71575d9 | 213 | SCM_STACKITEM *stack_start) |
d564d753 | 214 | { |
8938d022 | 215 | SCM old_rootcont, old_winds; |
e71575d9 | 216 | struct cwdr_handler_data my_handler_data; |
d564d753 MD |
217 | SCM answer; |
218 | ||
e71575d9 | 219 | /* Create a fresh root continuation. */ |
d564d753 MD |
220 | { |
221 | SCM new_rootcont; | |
5f144b10 | 222 | |
d564d753 | 223 | SCM_REDEFER_INTS; |
5f144b10 | 224 | { |
4c9419ac MV |
225 | scm_t_contregs *contregs = scm_gc_malloc (sizeof (scm_t_contregs), |
226 | "continuation"); | |
5f144b10 GH |
227 | |
228 | contregs->num_stack_items = 0; | |
229 | contregs->dynenv = SCM_EOL; | |
230 | contregs->base = stack_start; | |
231 | contregs->seq = ++n_dynamic_roots; | |
232 | contregs->throw_value = SCM_BOOL_F; | |
d564d753 | 233 | #ifdef DEBUG_EXTENSIONS |
5f144b10 | 234 | contregs->dframe = 0; |
d564d753 | 235 | #endif |
5f144b10 GH |
236 | SCM_NEWSMOB (new_rootcont, scm_tc16_continuation, contregs); |
237 | } | |
8938d022 MD |
238 | old_rootcont = scm_rootcont; |
239 | scm_rootcont = new_rootcont; | |
d564d753 MD |
240 | SCM_REALLOW_INTS; |
241 | } | |
242 | ||
8938d022 MD |
243 | /* Exit caller's dynamic state. |
244 | */ | |
245 | old_winds = scm_dynwinds; | |
246 | scm_dowinds (SCM_EOL, scm_ilength (scm_dynwinds)); | |
d564d753 | 247 | #ifdef DEBUG_EXTENSIONS |
308277cb | 248 | SCM_DFRAME (old_rootcont) = scm_last_debug_frame; |
8938d022 | 249 | scm_last_debug_frame = 0; |
d564d753 | 250 | #endif |
650fa1ab | 251 | |
e71575d9 MV |
252 | { |
253 | my_handler_data.run_handler = 0; | |
816a6f06 | 254 | answer = scm_internal_catch (SCM_BOOL_T, |
e71575d9 MV |
255 | body, body_data, |
256 | cwdr_handler, &my_handler_data); | |
650fa1ab | 257 | } |
e71575d9 | 258 | |
d564d753 MD |
259 | scm_dowinds (old_winds, - scm_ilength (old_winds)); |
260 | SCM_REDEFER_INTS; | |
d564d753 | 261 | #ifdef DEBUG_EXTENSIONS |
308277cb | 262 | scm_last_debug_frame = SCM_DFRAME (old_rootcont); |
d564d753 | 263 | #endif |
308277cb | 264 | scm_rootcont = old_rootcont; |
d564d753 | 265 | SCM_REALLOW_INTS; |
e71575d9 MV |
266 | |
267 | /* Now run the real handler iff the body did a throw. */ | |
268 | if (my_handler_data.run_handler) | |
269 | return handler (handler_data, my_handler_data.tag, my_handler_data.args); | |
270 | else | |
271 | return answer; | |
d564d753 MD |
272 | } |
273 | ||
e71575d9 MV |
274 | /* The original CWDR for invoking Scheme code with a Scheme handler. */ |
275 | ||
276 | static SCM | |
277 | cwdr (SCM proc, SCM a1, SCM args, SCM handler, SCM_STACKITEM *stack_start) | |
278 | { | |
279 | struct cwdr_body_data c; | |
280 | ||
281 | c.a1 = a1; | |
282 | c.args = args; | |
283 | c.body_proc = proc; | |
284 | ||
285 | return scm_internal_cwdr (cwdr_body, &c, | |
286 | scm_handle_by_proc, &handler, | |
287 | stack_start); | |
288 | } | |
d564d753 | 289 | |
3b3b36dd | 290 | SCM_DEFINE (scm_call_with_dynamic_root, "call-with-dynamic-root", 2, 0, 0, |
1bbd0b84 | 291 | (SCM thunk, SCM handler), |
1bee0e70 | 292 | "Evaluate @code{(thunk)} in a new dynamic context, returning its value.\n\n" |
b380b885 MD |
293 | "If an error occurs during evaluation, apply @var{handler} to the\n" |
294 | "arguments to the throw, just as @code{throw} would. If this happens,\n" | |
295 | "@var{handler} is called outside the scope of the new root -- it is\n" | |
296 | "called in the same dynamic context in which\n" | |
297 | "@code{call-with-dynamic-root} was evaluated.\n\n" | |
298 | "If @var{thunk} captures a continuation, the continuation is rooted at\n" | |
299 | "the call to @var{thunk}. In particular, the call to\n" | |
300 | "@code{call-with-dynamic-root} is not captured. Therefore,\n" | |
301 | "@code{call-with-dynamic-root} always returns at most one time.\n\n" | |
302 | "Before calling @var{thunk}, the dynamic-wind chain is un-wound back to\n" | |
303 | "the root and a new chain started for @var{thunk}. Therefore, this call\n" | |
304 | "may not do what you expect:\n\n" | |
1e6808ea | 305 | "@lisp\n" |
b380b885 MD |
306 | ";; Almost certainly a bug:\n" |
307 | "(with-output-to-port\n" | |
308 | " some-port\n\n" | |
309 | " (lambda ()\n" | |
310 | " (call-with-dynamic-root\n" | |
311 | " (lambda ()\n" | |
312 | " (display 'fnord)\n" | |
313 | " (newline))\n" | |
314 | " (lambda (errcode) errcode))))\n" | |
1e6808ea | 315 | "@end lisp\n\n" |
2a2a730b | 316 | "The problem is, on what port will @samp{fnord} be displayed? You\n" |
b380b885 MD |
317 | "might expect that because of the @code{with-output-to-port} that\n" |
318 | "it will be displayed on the port bound to @code{some-port}. But it\n" | |
319 | "probably won't -- before evaluating the thunk, dynamic winds are\n" | |
320 | "unwound, including those created by @code{with-output-to-port}.\n" | |
321 | "So, the standard output port will have been re-set to its default value\n" | |
322 | "before @code{display} is evaluated.\n\n" | |
323 | "(This function was added to Guile mostly to help calls to functions in C\n" | |
324 | "libraries that can not tolerate non-local exits or calls that return\n" | |
325 | "multiple times. If such functions call back to the interpreter, it should\n" | |
326 | "be under a new dynamic root.)") | |
1bbd0b84 | 327 | #define FUNC_NAME s_scm_call_with_dynamic_root |
d564d753 MD |
328 | { |
329 | SCM_STACKITEM stack_place; | |
8938d022 | 330 | return cwdr (thunk, SCM_EOL, SCM_EOL, handler, &stack_place); |
d564d753 | 331 | } |
1bbd0b84 | 332 | #undef FUNC_NAME |
d564d753 | 333 | |
3b3b36dd | 334 | SCM_DEFINE (scm_dynamic_root, "dynamic-root", 0, 0, 0, |
1bbd0b84 | 335 | (), |
b380b885 MD |
336 | "Return an object representing the current dynamic root.\n\n" |
337 | "These objects are only useful for comparison using @code{eq?}.\n" | |
338 | "They are currently represented as numbers, but your code should\n" | |
339 | "in no way depend on this.") | |
1bbd0b84 | 340 | #define FUNC_NAME s_scm_dynamic_root |
d564d753 MD |
341 | { |
342 | return scm_ulong2num (SCM_SEQ (scm_root->rootcont)); | |
343 | } | |
1bbd0b84 | 344 | #undef FUNC_NAME |
d564d753 | 345 | |
d564d753 | 346 | SCM |
1bbd0b84 | 347 | scm_apply_with_dynamic_root (SCM proc, SCM a1, SCM args, SCM handler) |
d564d753 MD |
348 | { |
349 | SCM_STACKITEM stack_place; | |
8938d022 | 350 | return cwdr (proc, a1, args, handler, &stack_place); |
d564d753 | 351 | } |
0f2d19dd JB |
352 | |
353 | \f | |
354 | ||
d564d753 MD |
355 | void |
356 | scm_init_root () | |
357 | { | |
cc4feeca | 358 | scm_tc16_root = scm_make_smob_type ("root", sizeof (struct scm_root_state)); |
e841c3e0 KN |
359 | scm_set_smob_mark (scm_tc16_root, root_mark); |
360 | scm_set_smob_print (scm_tc16_root, root_print); | |
cc4feeca | 361 | |
a0599745 | 362 | #include "libguile/root.x" |
d564d753 | 363 | } |
89e00824 ML |
364 | |
365 | /* | |
366 | Local Variables: | |
367 | c-file-style: "gnu" | |
368 | End: | |
369 | */ |