1 /* Copyright (C) 1995,1996,1997,1998, 1999, 2000 Free Software Foundation, Inc.
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)
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.
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
15 * the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
16 * Boston, MA 02111-1307 USA
18 * As a special exception, the Free Software Foundation gives permission
19 * for additional uses of the text contained in its release of GUILE.
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.
27 * This exception does not however invalidate any other reasons why
28 * the executable file might be covered by the GNU General Public License.
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.
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.
40 * If you do not wish that, delete this exception notice. */
42 /* Software engineering face-lift by Greg J. Badros, 11-Dec-1999,
43 gjb@cs.washington.edu, http://www.cs.washington.edu/homes/gjb */
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"
58 #include "libguile/root.h"
61 /* Define this if you want to try out the stack allocation of cwdr's
62 jumpbuf. It works for me but I'm still worried that the dynwinds
63 might be able to make a mess. */
65 #undef USE_STACKJMPBUF
67 SCM scm_sys_protects
[SCM_NUM_PROTECTS
];
72 struct scm_root_state
*scm_root
;
80 scm_root_state
*s
= SCM_ROOT_STATE (root
);
82 scm_gc_mark (s
->rootcont
);
83 scm_gc_mark (s
->dynwinds
);
84 scm_gc_mark (s
->continuation_stack
);
85 scm_gc_mark (s
->continuation_stack_ptr
);
86 scm_gc_mark (s
->progargs
);
87 scm_gc_mark (s
->exitval
);
88 scm_gc_mark (s
->cur_inp
);
89 scm_gc_mark (s
->cur_outp
);
90 scm_gc_mark (s
->cur_errp
);
91 scm_gc_mark (s
->def_inp
);
92 scm_gc_mark (s
->def_outp
);
93 scm_gc_mark (s
->def_errp
);
94 /* No need to gc mark def_loadp */
95 scm_gc_mark (s
->fluids
);
96 return SCM_ROOT_STATE (root
) -> parent
;
101 print_root (SCM exp
,SCM port
,scm_print_state
*pstate
)
103 scm_puts ("#<root ", port
);
104 scm_intprint(SCM_SEQ (SCM_ROOT_STATE (exp
) -> rootcont
), 16, port
);
113 scm_make_root (SCM parent
)
116 scm_root_state
*root_state
;
118 root_state
= (scm_root_state
*) scm_must_malloc (sizeof (scm_root_state
),
120 if (SCM_ROOTP (parent
))
122 memcpy (root_state
, SCM_ROOT_STATE (parent
), sizeof (scm_root_state
));
123 scm_copy_fluids (root_state
);
124 root_state
->parent
= parent
;
128 root_state
->parent
= SCM_BOOL_F
;
130 /* Initialize everything right now, in case a GC happens early. */
132 = root_state
->dynwinds
133 = root_state
->continuation_stack
134 = root_state
->continuation_stack_ptr
135 = root_state
->progargs
136 = root_state
->exitval
137 = root_state
->cur_inp
138 = root_state
->cur_outp
139 = root_state
->cur_errp
140 = root_state
->def_inp
141 = root_state
->def_outp
142 = root_state
->def_errp
143 = root_state
->cur_loadp
150 SCM_NEWSMOB (root
, scm_tc16_root
, root_state
);
151 root_state
->handle
= root
;
156 /* {call-with-dynamic-root}
158 * Suspending the current thread to evaluate a thunk on the
159 * same C stack but under a new root.
161 * Calls to call-with-dynamic-root return exactly once (unless
162 * the process is somehow exitted). */
164 /* Some questions about cwdr:
166 Couldn't the body just be a closure? Do we really need to pass
169 The semantics are a lot like catch's; in fact, we call
170 scm_internal_catch to take care of that part of things. Wouldn't
171 it be cleaner to say that uncaught throws just disappear into the
172 ether (or print a message to stderr), and let the caller use catch
173 themselves if they want to?
178 SCM scm_exitval
; /* INUM with return value */
180 static int n_dynamic_roots
= 0;
183 /* cwdr fills out both of these structures, and then passes a pointer
184 to them through scm_internal_catch to the cwdr_body and
185 cwdr_handler functions, to tell them how to behave and to get
186 information back from them.
188 A cwdr is a lot like a catch, except there is no tag (all
189 exceptions are caught), and the body procedure takes the arguments
190 passed to cwdr as A1 and ARGS. The handler is also special since
191 it is not directly run from scm_internal_catch. It is executed
192 outside the new dynamic root. */
194 struct cwdr_body_data
{
195 /* Arguments to pass to the cwdr body function. */
198 /* Scheme procedure to use as body of cwdr. */
202 struct cwdr_handler_data
{
203 /* Do we need to run the handler? */
206 /* The tag and args to pass it. */
211 /* Invoke the body of a cwdr, assuming that the throw handler has
212 already been set up. DATA points to a struct set up by cwdr that
213 says what proc to call, and what args to apply it to.
215 With a little thought, we could replace this with scm_body_thunk,
216 but I don't want to mess with that at the moment. */
218 cwdr_body (void *data
)
220 struct cwdr_body_data
*c
= (struct cwdr_body_data
*) data
;
222 return scm_apply (c
->body_proc
, c
->a1
, c
->args
);
225 /* Record the fact that the body of the cwdr has thrown. Record
226 enough information to invoke the handler later when the dynamic
227 root has been deestablished. */
230 cwdr_handler (void *data
, SCM tag
, SCM args
)
232 struct cwdr_handler_data
*c
= (struct cwdr_handler_data
*) data
;
237 return SCM_UNSPECIFIED
;
240 /* This is the basic code for new root creation.
242 * WARNING! The order of actions in this routine is in many ways
243 * critical. E. g., it is essential that an error doesn't leave Guile
244 * in a messed up state. */
247 scm_internal_cwdr (scm_catch_body_t body
, void *body_data
,
248 scm_catch_handler_t handler
, void *handler_data
,
249 SCM_STACKITEM
*stack_start
)
251 #ifdef USE_STACKJMPBUF
252 scm_contregs static_contregs
;
254 int old_ints_disabled
= scm_ints_disabled
;
255 SCM old_rootcont
, old_winds
;
256 struct cwdr_handler_data my_handler_data
;
259 /* Create a fresh root continuation. */
262 SCM_NEWCELL (new_rootcont
);
264 #ifdef USE_STACKJMPBUF
265 SCM_SET_CONTREGS (new_rootcont
, &static_contregs
);
267 SCM_SET_CONTREGS (new_rootcont
,
268 scm_must_malloc (sizeof (scm_contregs
),
269 "inferior root continuation"));
271 SCM_SET_CELL_TYPE (new_rootcont
, scm_tc7_contin
);
272 SCM_DYNENV (new_rootcont
) = SCM_EOL
;
273 SCM_BASE (new_rootcont
) = stack_start
;
274 SCM_SEQ (new_rootcont
) = ++n_dynamic_roots
;
275 #ifdef DEBUG_EXTENSIONS
276 SCM_DFRAME (new_rootcont
) = 0;
278 old_rootcont
= scm_rootcont
;
279 scm_rootcont
= new_rootcont
;
283 /* Exit caller's dynamic state.
285 old_winds
= scm_dynwinds
;
286 scm_dowinds (SCM_EOL
, scm_ilength (scm_dynwinds
));
287 #ifdef DEBUG_EXTENSIONS
288 SCM_DFRAME (old_rootcont
) = scm_last_debug_frame
;
289 scm_last_debug_frame
= 0;
293 my_handler_data
.run_handler
= 0;
294 answer
= scm_internal_catch (SCM_BOOL_T
,
296 cwdr_handler
, &my_handler_data
);
299 scm_dowinds (old_winds
, - scm_ilength (old_winds
));
301 #ifdef USE_STACKCJMPBUF
302 SCM_SET_CONTREGS (scm_rootcont
, NULL
);
304 #ifdef DEBUG_EXTENSIONS
305 scm_last_debug_frame
= SCM_DFRAME (old_rootcont
);
307 scm_rootcont
= old_rootcont
;
309 scm_ints_disabled
= old_ints_disabled
;
311 /* Now run the real handler iff the body did a throw. */
312 if (my_handler_data
.run_handler
)
313 return handler (handler_data
, my_handler_data
.tag
, my_handler_data
.args
);
318 /* The original CWDR for invoking Scheme code with a Scheme handler. */
321 cwdr (SCM proc
, SCM a1
, SCM args
, SCM handler
, SCM_STACKITEM
*stack_start
)
323 struct cwdr_body_data c
;
329 return scm_internal_cwdr (cwdr_body
, &c
,
330 scm_handle_by_proc
, &handler
,
334 SCM_DEFINE (scm_call_with_dynamic_root
, "call-with-dynamic-root", 2, 0, 0,
335 (SCM thunk
, SCM handler
),
336 "Evaluate @code{(thunk)} in a new dynamic context, returning its value.\n\n"
337 "If an error occurs during evaluation, apply @var{handler} to the\n"
338 "arguments to the throw, just as @code{throw} would. If this happens,\n"
339 "@var{handler} is called outside the scope of the new root -- it is\n"
340 "called in the same dynamic context in which\n"
341 "@code{call-with-dynamic-root} was evaluated.\n\n"
342 "If @var{thunk} captures a continuation, the continuation is rooted at\n"
343 "the call to @var{thunk}. In particular, the call to\n"
344 "@code{call-with-dynamic-root} is not captured. Therefore,\n"
345 "@code{call-with-dynamic-root} always returns at most one time.\n\n"
346 "Before calling @var{thunk}, the dynamic-wind chain is un-wound back to\n"
347 "the root and a new chain started for @var{thunk}. Therefore, this call\n"
348 "may not do what you expect:\n\n"
350 ";; Almost certainly a bug:\n"
351 "(with-output-to-port\n"
354 " (call-with-dynamic-root\n"
356 " (display 'fnord)\n"
358 " (lambda (errcode) errcode))))\n"
360 "The problem is, on what port will @samp{fnord} be displayed? You\n"
361 "might expect that because of the @code{with-output-to-port} that\n"
362 "it will be displayed on the port bound to @code{some-port}. But it\n"
363 "probably won't -- before evaluating the thunk, dynamic winds are\n"
364 "unwound, including those created by @code{with-output-to-port}.\n"
365 "So, the standard output port will have been re-set to its default value\n"
366 "before @code{display} is evaluated.\n\n"
367 "(This function was added to Guile mostly to help calls to functions in C\n"
368 "libraries that can not tolerate non-local exits or calls that return\n"
369 "multiple times. If such functions call back to the interpreter, it should\n"
370 "be under a new dynamic root.)")
371 #define FUNC_NAME s_scm_call_with_dynamic_root
373 SCM_STACKITEM stack_place
;
374 return cwdr (thunk
, SCM_EOL
, SCM_EOL
, handler
, &stack_place
);
378 SCM_DEFINE (scm_dynamic_root
, "dynamic-root", 0, 0, 0,
380 "Return an object representing the current dynamic root.\n\n"
381 "These objects are only useful for comparison using @code{eq?}.\n"
382 "They are currently represented as numbers, but your code should\n"
383 "in no way depend on this.")
384 #define FUNC_NAME s_scm_dynamic_root
386 return scm_ulong2num (SCM_SEQ (scm_root
->rootcont
));
391 scm_apply_with_dynamic_root (SCM proc
, SCM a1
, SCM args
, SCM handler
)
393 SCM_STACKITEM stack_place
;
394 return cwdr (proc
, a1
, args
, handler
, &stack_place
);
399 #if (SCM_DEBUG_DEPRECATED == 0)
401 /* Call thunk(closure) underneath a top-level error handler.
402 * If an error occurs, pass the exitval through err_filter and return it.
403 * If no error occurs, return the value of thunk.
407 typedef int setjmp_type
;
409 typedef long setjmp_type
;
414 scm_call_catching_errors (SCM (*thunk
)(), SCM (*err_filter
)(), void *closure
)
418 #ifdef DEBUG_EXTENSIONS
419 SCM_DFRAME (scm_rootcont
) = scm_last_debug_frame
;
421 i
= setjmp (SCM_JMPBUF (scm_rootcont
));
422 scm_stack_checking_enabled_p
= SCM_STACK_CHECKING_P
;
425 scm_gc_heap_lock
= 0;
426 answer
= thunk (closure
);
430 scm_gc_heap_lock
= 1;
431 answer
= err_filter (scm_exitval
, closure
);
436 #endif /* SCM_DEBUG_DEPRECATED == 0 */
442 scm_tc16_root
= scm_make_smob_type ("root", sizeof (struct scm_root_state
));
443 scm_set_smob_mark (scm_tc16_root
, mark_root
);
444 scm_set_smob_print (scm_tc16_root
, print_root
);
446 #include "libguile/root.x"