-/* Copyright (C) 1995,1996 Free Software Foundation, Inc.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2, or (at your option)
- * any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this software; see the file COPYING. If not, write to
- * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
- *
- * As a special exception, the Free Software Foundation gives permission
- * for additional uses of the text contained in its release of GUILE.
- *
- * The exception is that, if you link the GUILE library with other files
- * to produce an executable, this does not by itself cause the
- * resulting executable to be covered by the GNU General Public License.
- * Your use of that executable is in no way restricted on account of
- * linking the GUILE library code into it.
- *
- * This exception does not however invalidate any other reasons why
- * the executable file might be covered by the GNU General Public License.
- *
- * This exception applies only to the code released by the
- * Free Software Foundation under the name GUILE. If you copy
- * code from other Free Software Foundation releases into a copy of
- * GUILE, as the General Public License permits, the exception does
- * not apply to the code that you add in this way. To avoid misleading
- * anyone as to the status of such modified files, you must delete
- * this exception notice from them.
- *
- * If you write modifications of your own for GUILE, it is your choice
- * whether to permit this exception to apply to your modifications.
- * If you do not wish that, delete this exception notice.
- */
-\f
-
-#include <stdio.h>
-#include "_scm.h"
-#include "genio.h"
-#include "smob.h"
-#include "alist.h"
-#include "eval.h"
-#include "eq.h"
-#include "dynwind.h"
-#include "backtrace.h"
-#ifdef DEBUG_EXTENSIONS
-#include "debug.h"
-#endif
-#include "continuations.h"
-#include "stackchk.h"
-
-#include "throw.h"
-
-\f
-/* the jump buffer data structure */
-static int scm_tc16_jmpbuffer;
-
-#define SCM_JMPBUFP(O) (SCM_TYP16(O) == scm_tc16_jmpbuffer)
-#define JBACTIVE(O) (SCM_CAR (O) & (1L << 16L))
-#define ACTIVATEJB(O) (SCM_SETOR_CAR (O, (1L << 16L)))
-#define DEACTIVATEJB(O) (SCM_SETAND_CAR (O, ~(1L << 16L)))
-
-#ifndef DEBUG_EXTENSIONS
-#define JBJMPBUF(O) ((jmp_buf*)SCM_CDR (O) )
-#define SETJBJMPBUF SCM_SETCDR
-#else
-#define SCM_JBDFRAME(O) ((scm_debug_frame*)SCM_CAR (SCM_CDR (O)) )
-#define JBJMPBUF(O) ((jmp_buf*)SCM_CDR (SCM_CDR (O)) )
-#define SCM_SETJBDFRAME(O,X) SCM_SETCAR (SCM_CDR (O), (SCM)(X))
-#define SETJBJMPBUF(O,X) SCM_SETCDR(SCM_CDR (O), X)
-
-static scm_sizet freejb SCM_P ((SCM jbsmob));
-
-static scm_sizet
-freejb (jbsmob)
- SCM jbsmob;
-{
- scm_must_free ((char *) SCM_CDR (jbsmob));
- return sizeof (scm_cell);
-}
-#endif
-
-static int printjb SCM_P ((SCM exp, SCM port, scm_print_state *pstate));
-static int
-printjb (exp, port, pstate)
- SCM exp;
- SCM port;
- scm_print_state *pstate;
-{
- scm_gen_puts (scm_regular_string, "#<jmpbuffer ", port);
- scm_gen_puts (scm_regular_string, JBACTIVE(exp) ? "(active) " : "(inactive) ", port);
- scm_intprint((SCM) JBJMPBUF(exp), 16, port);
- scm_gen_putc ('>', port);
- return 1 ;
-}
-
-static scm_smobfuns jbsmob = {
- scm_mark0,
-#ifdef DEBUG_EXTENSIONS
- freejb,
-#else
- scm_free0,
-#endif
- printjb,
- 0
-};
-
-static SCM make_jmpbuf SCM_P ((void));
-static SCM
-make_jmpbuf ()
-{
- SCM answer;
- SCM_NEWCELL (answer);
- SCM_REDEFER_INTS;
- {
-#ifdef DEBUG_EXTENSIONS
- char *mem = scm_must_malloc (sizeof (scm_cell), "jb");
- SCM_SETCDR (answer, (SCM) mem);
-#endif
- SCM_SETCAR (answer, scm_tc16_jmpbuffer);
- SETJBJMPBUF(answer, (jmp_buf *)0);
- DEACTIVATEJB(answer);
- }
- SCM_REALLOW_INTS;
- return answer;
-}
-
-\f
-/* scm_internal_catch (the guts of catch) */
-
-struct jmp_buf_and_retval /* use only on the stack, in scm_catch */
-{
- jmp_buf buf; /* must be first */
- SCM throw_tag;
- SCM retval;
-};
-
-
-/* scm_internal_catch is the guts of catch. It handles all the
- mechanics of setting up a catch target, invoking the catch body,
- and perhaps invoking the handler if the body does a throw.
-
- The function is designed to be usable from C code, but is general
- enough to implement all the semantics Guile Scheme expects from
- throw.
-
- TAG is the catch tag. Typically, this is a symbol, but this
- function doesn't actually care about that.
-
- BODY is a pointer to a C function which runs the body of the catch;
- this is the code you can throw from. We call it like this:
- BODY (BODY_DATA, JMPBUF)
- where:
- BODY_DATA is just the BODY_DATA argument we received; we pass it
- through to BODY as its first argument. The caller can make
- BODY_DATA point to anything useful that BODY might need.
- JMPBUF is the Scheme jmpbuf object corresponding to this catch,
- which we have just created and initialized.
-
- HANDLER is a pointer to a C function to deal with a throw to TAG,
- should one occur. We call it like this:
- HANDLER (HANDLER_DATA, THROWN_TAG, THROW_ARGS)
- where
- HANDLER_DATA is the HANDLER_DATA argument we recevied; it's the
- same idea as BODY_DATA above.
- THROWN_TAG is the tag that the user threw to; usually this is
- TAG, but it could be something else if TAG was #t (i.e., a
- catch-all), or the user threw to a jmpbuf.
- THROW_ARGS is the list of arguments the user passed to the THROW
- function.
-
- BODY_DATA is just a pointer we pass through to BODY. HANDLER_DATA
- is just a pointer we pass through to HANDLER. We don't actually
- use either of those pointers otherwise ourselves. The idea is
- that, if our caller wants to communicate something to BODY or
- HANDLER, it can pass a pointer to it as MUMBLE_DATA, which BODY and
- HANDLER can then use. Think of it as a way to make BODY and
- HANDLER closures, not just functions; MUMBLE_DATA points to the
- enclosed variables.
-
- Of course, it's up to the caller to make sure that any data a
- MUMBLE_DATA needs is protected from GC. A common way to do this is
- to make MUMBLE_DATA a pointer to data stored in an automatic
- structure variable; since the collector must scan the stack for
- references anyway, this assures that any references in MUMBLE_DATA
- will be found. */
-
-SCM
-scm_internal_catch (tag, body, body_data, handler, handler_data)
- SCM tag;
- scm_catch_body_t body;
- void *body_data;
- scm_catch_handler_t handler;
- void *handler_data;
-{
- struct jmp_buf_and_retval jbr;
- SCM jmpbuf;
- SCM answer;
-
- jmpbuf = make_jmpbuf ();
- answer = SCM_EOL;
- scm_dynwinds = scm_acons (tag, jmpbuf, scm_dynwinds);
- SETJBJMPBUF(jmpbuf, &jbr.buf);
-#ifdef DEBUG_EXTENSIONS
- SCM_SETJBDFRAME(jmpbuf, scm_last_debug_frame);
-#endif
- if (setjmp (jbr.buf))
- {
- SCM throw_tag;
- SCM throw_args;
-
-#ifdef STACK_CHECKING
- scm_stack_checking_enabled_p = SCM_STACK_CHECKING_P;
-#endif
- SCM_REDEFER_INTS;
- DEACTIVATEJB (jmpbuf);
- scm_dynwinds = SCM_CDR (scm_dynwinds);
- SCM_REALLOW_INTS;
- throw_args = jbr.retval;
- throw_tag = jbr.throw_tag;
- jbr.throw_tag = SCM_EOL;
- jbr.retval = SCM_EOL;
- answer = handler (handler_data, throw_tag, throw_args);
- }
- else
- {
- ACTIVATEJB (jmpbuf);
- answer = body (body_data, jmpbuf);
- SCM_REDEFER_INTS;
- DEACTIVATEJB (jmpbuf);
- scm_dynwinds = SCM_CDR (scm_dynwinds);
- SCM_REALLOW_INTS;
- }
- return answer;
-}
-
-
-\f
-/* scm_internal_lazy_catch (the guts of lazy catching) */
-
-/* The smob tag for lazy_catch smobs. */
-static long tc16_lazy_catch;
-
-/* This is the structure we put on the wind list for a lazy catch. It
- stores the handler function to call, and the data pointer to pass
- through to it. It's not a Scheme closure, but it is a function
- with data, so the term "closure" is appropriate in its broader
- sense.
-
- (We don't need anything like this in the "eager" catch code,
- because the same C frame runs both the body and the handler.) */
-struct lazy_catch {
- scm_catch_handler_t handler;
- void *handler_data;
-};
-
-/* Strictly speaking, we could just pass a zero for our print
- function, because we don't need to print them. They should never
- appear in normal data structures, only in the wind list. However,
- it might be nice for debugging someday... */
-static int
-print_lazy_catch (SCM closure, SCM port, scm_print_state *pstate)
-{
- struct lazy_catch *c = (struct lazy_catch *) SCM_CDR (closure);
- char buf[200];
-
- sprintf (buf, "#<lazy-catch 0x%lx 0x%lx>",
- (long) c->handler, (long) c->handler_data);
- scm_gen_puts (scm_regular_string, buf, port);
-
- return 1;
-}
-
-static scm_smobfuns lazy_catch_funs = {
- scm_mark0, scm_free0, print_lazy_catch, 0
-};
-
-
-/* Given a pointer to a lazy catch structure, return a smob for it,
- suitable for inclusion in the wind list. ("Ah yes, a Château
- Gollombiere '72, non?"). */
-static SCM
-make_lazy_catch (struct lazy_catch *c)
-{
- SCM smob;
-
- SCM_NEWCELL (smob);
- SCM_SETCDR (smob, c);
- SCM_SETCAR (smob, tc16_lazy_catch);
-
- return smob;
-}
-
-#define SCM_LAZY_CATCH_P(obj) \
- (SCM_NIMP (obj) && (SCM_CAR (obj) == tc16_lazy_catch))
-
-
-/* Exactly like scm_internal_catch, except:
- - It does not unwind the stack (this is the major difference).
- - If handler returns, its value is returned from the throw.
- - BODY always receives #f as its JMPBUF argument (since there's no
- jmpbuf associated with a lazy catch, because we don't unwind the
- stack.) */
-SCM
-scm_internal_lazy_catch (tag, body, body_data, handler, handler_data)
- SCM tag;
- scm_catch_body_t body;
- void *body_data;
- scm_catch_handler_t handler;
- void *handler_data;
-{
- SCM lazy_catch, answer;
- struct lazy_catch c;
-
- c.handler = handler;
- c.handler_data = handler_data;
- lazy_catch = make_lazy_catch (&c);
-
- SCM_REDEFER_INTS;
- scm_dynwinds = scm_acons (tag, lazy_catch, scm_dynwinds);
- SCM_REALLOW_INTS;
-
- answer = (*body) (body_data, SCM_BOOL_F);
-
- SCM_REDEFER_INTS;
- scm_dynwinds = SCM_CDR (scm_dynwinds);
- SCM_REALLOW_INTS;
-
- return answer;
-}
-
-
-\f
-/* body and handler functions for use with either of the above */
-
-/* This is a body function you can pass to scm_internal_catch if you
- want the body to be like Scheme's `catch' --- a thunk, or a
- function of one argument if the tag is #f.
-
- BODY_DATA is a pointer to a scm_body_thunk_data structure, which
- contains the Scheme procedure to invoke as the body, and the tag
- we're catching. If the tag is #f, then we pass JMPBUF (created by
- scm_internal_catch) to the body procedure; otherwise, the body gets
- no arguments. */
-
-SCM
-scm_body_thunk (body_data, jmpbuf)
- void *body_data;
- SCM jmpbuf;
-{
- struct scm_body_thunk_data *c = (struct scm_body_thunk_data *) body_data;
-
- if (c->tag == SCM_BOOL_F)
- return scm_apply (c->body_proc, scm_cons (jmpbuf, SCM_EOL), SCM_EOL);
- else
- return scm_apply (c->body_proc, SCM_EOL, SCM_EOL);
-}
-
-
-/* This is a handler function you can pass to scm_internal_catch if
- you want the handler to act like Scheme's catch --- call a
- procedure with the tag and the throw arguments.
-
- If the user does a throw to this catch, this function runs a
- handler procedure written in Scheme. HANDLER_DATA is a pointer to
- an SCM variable holding the Scheme procedure object to invoke. It
- ought to be a pointer to an automatic variable (i.e., one living on
- the stack), or the procedure object should be otherwise protected
- from GC. */
-SCM
-scm_handle_by_proc (handler_data, tag, throw_args)
- void *handler_data;
- SCM tag;
- SCM throw_args;
-{
- SCM *handler_proc_p = (SCM *) handler_data;
-
- return scm_apply (*handler_proc_p, scm_cons (tag, throw_args), SCM_EOL);
-}
-
-
-/* This is a handler function to use if you want scheme to print a
- message and die. Useful for dealing with throws to uncaught keys
- at the top level.
-
- At boot time, we establish a catch-all that uses this as its handler.
- 1) If the user wants something different, they can use (catch #t
- ...) to do what they like.
- 2) Outside the context of a read-eval-print loop, there isn't
- anything else good to do; libguile should not assume the existence
- of a read-eval-print loop.
- 3) Given that we shouldn't do anything complex, it's much more
- robust to do it in C code.
-
- HANDLER_DATA, if non-zero, is assumed to be a char * pointing to a
- message header to print; if zero, we use "guile" instead. That
- text is followed by a colon, then the message described by ARGS. */
-
-SCM
-scm_handle_by_message (handler_data, tag, args)
- void *handler_data;
- SCM tag;
- SCM args;
-{
- char *prog_name = (char *) handler_data;
- SCM p = scm_def_errp;
-
- if (SCM_NFALSEP (scm_eq_p (tag, SCM_CAR (scm_intern0 ("quit")))))
- exit (scm_exit_status (args));
-
- if (! prog_name)
- prog_name = "guile";
-
- scm_gen_puts (scm_regular_string, prog_name, p);
- scm_gen_puts (scm_regular_string, ": ", p);
-
- if (scm_ilength (args) >= 3)
- {
- SCM message = SCM_CADR (args);
- SCM parts = SCM_CADDR (args);
-
- scm_display_error_message (message, parts, p);
- }
- else
- {
- scm_gen_puts (scm_regular_string, "uncaught throw to ", p);
- scm_prin1 (tag, p, 0);
- scm_gen_puts (scm_regular_string, ": ", p);
- scm_prin1 (args, p, 1);
- scm_gen_putc ('\n', p);
- }
-
- exit (2);
-}
-
-
-/* Derive the an exit status from the arguments to (quit ...). */
-int
-scm_exit_status (args)
- SCM args;
-{
- if (SCM_NNULLP (args))
- {
- SCM cqa = SCM_CAR (args);
-
- if (SCM_INUMP (cqa))
- return (SCM_INUM (cqa));
- else if (SCM_FALSEP (cqa))
- return 1;
- }
- return 0;
-}
-
-
-
-\f
-/* the Scheme-visible CATCH and LAZY-CATCH functions */
-
-SCM_PROC(s_catch, "catch", 3, 0, 0, scm_catch);
-SCM
-scm_catch (tag, thunk, handler)
- SCM tag;
- SCM thunk;
- SCM handler;
-{
- struct scm_body_thunk_data c;
-
- SCM_ASSERT ((tag == SCM_BOOL_F)
- || (SCM_NIMP(tag) && SCM_SYMBOLP(tag))
- || (tag == SCM_BOOL_T),
- tag, SCM_ARG1, s_catch);
-
- c.tag = tag;
- c.body_proc = thunk;
-
- /* scm_internal_catch takes care of all the mechanics of setting up
- a catch tag; we tell it to call scm_body_thunk to run the body,
- and scm_handle_by_proc to deal with any throws to this catch.
- The former receives a pointer to c, telling it how to behave.
- The latter receives a pointer to HANDLER, so it knows who to call. */
- return scm_internal_catch (tag,
- scm_body_thunk, &c,
- scm_handle_by_proc, &handler);
-}
-
-
-SCM_PROC(s_lazy_catch, "lazy-catch", 3, 0, 0, scm_lazy_catch);
-SCM
-scm_lazy_catch (tag, thunk, handler)
- SCM tag;
- SCM thunk;
- SCM handler;
-{
- struct scm_body_thunk_data c;
-
- SCM_ASSERT ((SCM_NIMP(tag) && SCM_SYMBOLP(tag))
- || (tag == SCM_BOOL_T),
- tag, SCM_ARG1, s_lazy_catch);
-
- c.tag = tag;
- c.body_proc = thunk;
-
- /* scm_internal_lazy_catch takes care of all the mechanics of
- setting up a lazy catch tag; we tell it to call scm_body_thunk to
- run the body, and scm_handle_by_proc to deal with any throws to
- this catch. The former receives a pointer to c, telling it how
- to behave. The latter receives a pointer to HANDLER, so it knows
- who to call. */
- return scm_internal_lazy_catch (tag,
- scm_body_thunk, &c,
- scm_handle_by_proc, &handler);
-}
-
-
-\f
-/* throwing */
-
-SCM_PROC(s_throw, "throw", 1, 0, 1, scm_throw);
-SCM
-scm_throw (key, args)
- SCM key;
- SCM args;
-{
- /* May return if handled by lazy catch. */
- return scm_ithrow (key, args, 1);
-}
-
-
-SCM
-scm_ithrow (key, args, noreturn)
- SCM key;
- SCM args;
- int noreturn;
-{
- SCM jmpbuf;
- SCM wind_goal;
-
- if (SCM_NIMP (key) && SCM_JMPBUFP (key))
- {
- jmpbuf = key;
- if (noreturn)
- {
- SCM_ASSERT (JBACTIVE (jmpbuf), jmpbuf,
- "throw to dynamically inactive catch",
- s_throw);
- }
- else if (!JBACTIVE (jmpbuf))
- return SCM_UNSPECIFIED;
- }
- else
- {
- SCM dynpair = SCM_UNDEFINED;
- SCM winds;
-
- if (noreturn)
- {
- SCM_ASSERT (SCM_NIMP (key) && SCM_SYMBOLP (key), key, SCM_ARG1,
- s_throw);
- }
- else if (!(SCM_NIMP (key) && SCM_SYMBOLP (key)))
- return SCM_UNSPECIFIED;
-
- /* Search the wind list for an appropriate catch.
- "Waiter, please bring us the wind list." */
- for (winds = scm_dynwinds; SCM_NIMP (winds); winds = SCM_CDR (winds))
- {
- if (! SCM_CONSP (winds))
- abort ();
-
- dynpair = SCM_CAR (winds);
- if (SCM_NIMP (dynpair) && SCM_CONSP (dynpair))
- {
- SCM this_key = SCM_CAR (dynpair);
-
- if (this_key == SCM_BOOL_T || this_key == key)
- break;
- }
- }
-
- /* If we didn't find anything, abort. scm_boot_guile should
- have established a catch-all, but obviously things are
- thoroughly screwed up. */
- if (winds == SCM_EOL)
- abort ();
-
- /* If the wind list is malformed, bail. */
- if (SCM_IMP (winds) || SCM_NCONSP (winds))
- abort ();
-
- if (dynpair != SCM_BOOL_F)
- jmpbuf = SCM_CDR (dynpair);
- else
- {
- if (!noreturn)
- return SCM_UNSPECIFIED;
- else
- {
- scm_exitval = scm_cons (key, args);
- scm_dowinds (SCM_EOL, scm_ilength (scm_dynwinds));
-#ifdef DEBUG_EXTENSIONS
- scm_last_debug_frame = SCM_DFRAME (scm_rootcont);
-#endif
- longjmp (SCM_JMPBUF (scm_rootcont), 1);
- }
- }
- }
- for (wind_goal = scm_dynwinds;
- SCM_CDAR (wind_goal) != jmpbuf;
- wind_goal = SCM_CDR (wind_goal))
- ;
-
- /* Is a lazy catch? In wind list entries for lazy catches, the key
- is bound to a lazy_catch smob, not a jmpbuf. */
- if (SCM_LAZY_CATCH_P (jmpbuf))
- {
- struct lazy_catch *c = (struct lazy_catch *) SCM_CDR (jmpbuf);
- SCM oldwinds = scm_dynwinds;
- SCM handle, answer;
- scm_dowinds (wind_goal, (scm_ilength (scm_dynwinds)
- - scm_ilength (wind_goal)));
- SCM_REDEFER_INTS;
- handle = scm_dynwinds;
- scm_dynwinds = SCM_CDR (scm_dynwinds);
- SCM_REALLOW_INTS;
- answer = (c->handler) (c->handler_data, key, args);
- SCM_REDEFER_INTS;
- SCM_SETCDR (handle, scm_dynwinds);
- scm_dynwinds = handle;
- SCM_REALLOW_INTS;
- scm_dowinds (oldwinds, (scm_ilength (scm_dynwinds)
- - scm_ilength (oldwinds)));
- return answer;
- }
-
- /* Otherwise, it's a normal catch. */
- else if (SCM_JMPBUFP (jmpbuf))
- {
- struct jmp_buf_and_retval * jbr;
- scm_dowinds (wind_goal, (scm_ilength (scm_dynwinds)
- - scm_ilength (wind_goal)));
- jbr = (struct jmp_buf_and_retval *)JBJMPBUF (jmpbuf);
- jbr->throw_tag = key;
- jbr->retval = args;
- }
-
- /* Otherwise, it's some random piece of junk. */
- else
- abort ();
-
-#ifdef DEBUG_EXTENSIONS
- scm_last_debug_frame = SCM_JBDFRAME (jmpbuf);
-#endif
- longjmp (*JBJMPBUF (jmpbuf), 1);
-}
-
-
-void
-scm_init_throw ()
-{
- scm_tc16_jmpbuffer = scm_newsmob (&jbsmob);
- tc16_lazy_catch = scm_newsmob (&lazy_catch_funs);
-#include "throw.x"
-}
+/* Copyright (C) 1995,1996,1997,1998,2000,2001, 2003, 2004, 2006 Free Software Foundation, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+
+\f
+
+#include <stdio.h>
+#include "libguile/_scm.h"
+#include "libguile/async.h"
+#include "libguile/smob.h"
+#include "libguile/alist.h"
+#include "libguile/eval.h"
+#include "libguile/eq.h"
+#include "libguile/dynwind.h"
+#include "libguile/backtrace.h"
+#include "libguile/debug.h"
+#include "libguile/continuations.h"
+#include "libguile/stackchk.h"
+#include "libguile/stacks.h"
+#include "libguile/fluids.h"
+#include "libguile/ports.h"
+#include "libguile/lang.h"
+#include "libguile/validate.h"
+#include "libguile/throw.h"
+#include "libguile/init.h"
+#include "libguile/strings.h"
+
+\f
+/* the jump buffer data structure */
+static scm_t_bits tc16_jmpbuffer;
+
+#define SCM_JMPBUFP(OBJ) SCM_TYP16_PREDICATE (tc16_jmpbuffer, OBJ)
+
+#define JBACTIVE(OBJ) (SCM_CELL_WORD_0 (OBJ) & (1L << 16L))
+#define ACTIVATEJB(x) \
+ (SCM_SET_CELL_WORD_0 ((x), (SCM_CELL_WORD_0 (x) | (1L << 16L))))
+#define DEACTIVATEJB(x) \
+ (SCM_SET_CELL_WORD_0 ((x), (SCM_CELL_WORD_0 (x) & ~(1L << 16L))))
+
+#define JBJMPBUF(OBJ) ((jmp_buf *) SCM_CELL_WORD_1 (OBJ))
+#define SETJBJMPBUF(x, v) (SCM_SET_CELL_WORD_1 ((x), (scm_t_bits) (v)))
+#define SCM_JBDFRAME(x) ((scm_t_debug_frame *) SCM_CELL_WORD_2 (x))
+#define SCM_SETJBDFRAME(x, v) (SCM_SET_CELL_WORD_2 ((x), (scm_t_bits) (v)))
+#define SCM_JBPREUNWIND(x) ((struct pre_unwind_data *) SCM_CELL_WORD_3 (x))
+#define SCM_SETJBPREUNWIND(x, v) (SCM_SET_CELL_WORD_3 ((x), (scm_t_bits) (v)))
+
+static int
+jmpbuffer_print (SCM exp, SCM port, scm_print_state *pstate SCM_UNUSED)
+{
+ scm_puts ("#<jmpbuffer ", port);
+ scm_puts (JBACTIVE(exp) ? "(active) " : "(inactive) ", port);
+ scm_uintprint((scm_t_bits) JBJMPBUF (exp), 16, port);
+ scm_putc ('>', port);
+ return 1 ;
+}
+
+static SCM
+make_jmpbuf (void)
+{
+ SCM answer;
+ SCM_CRITICAL_SECTION_START;
+ {
+ SCM_NEWSMOB2 (answer, tc16_jmpbuffer, 0, 0);
+ SETJBJMPBUF(answer, (jmp_buf *)0);
+ DEACTIVATEJB(answer);
+ }
+ SCM_CRITICAL_SECTION_END;
+ return answer;
+}
+
+\f
+/* scm_c_catch (the guts of catch) */
+
+struct jmp_buf_and_retval /* use only on the stack, in scm_catch */
+{
+ jmp_buf buf; /* must be first */
+ SCM throw_tag;
+ SCM retval;
+};
+
+/* These are the structures we use to store pre-unwind handling (aka
+ "lazy") information for a regular catch, and put on the wind list
+ for a "lazy" catch. They store the pre-unwind handler function to
+ call, and the data pointer to pass through to it. It's not a
+ Scheme closure, but it is a function with data, so the term
+ "closure" is appropriate in its broader sense.
+
+ (We don't need anything like this to run the normal (post-unwind)
+ catch handler, because the same C frame runs both the body and the
+ handler.) */
+
+struct pre_unwind_data {
+ scm_t_catch_handler handler;
+ void *handler_data;
+ int running;
+ int lazy_catch_p;
+};
+
+
+/* scm_c_catch is the guts of catch. It handles all the mechanics of
+ setting up a catch target, invoking the catch body, and perhaps
+ invoking the handler if the body does a throw.
+
+ The function is designed to be usable from C code, but is general
+ enough to implement all the semantics Guile Scheme expects from
+ throw.
+
+ TAG is the catch tag. Typically, this is a symbol, but this
+ function doesn't actually care about that.
+
+ BODY is a pointer to a C function which runs the body of the catch;
+ this is the code you can throw from. We call it like this:
+ BODY (BODY_DATA)
+ where:
+ BODY_DATA is just the BODY_DATA argument we received; we pass it
+ through to BODY as its first argument. The caller can make
+ BODY_DATA point to anything useful that BODY might need.
+
+ HANDLER is a pointer to a C function to deal with a throw to TAG,
+ should one occur. We call it like this:
+ HANDLER (HANDLER_DATA, THROWN_TAG, THROW_ARGS)
+ where
+ HANDLER_DATA is the HANDLER_DATA argument we recevied; it's the
+ same idea as BODY_DATA above.
+ THROWN_TAG is the tag that the user threw to; usually this is
+ TAG, but it could be something else if TAG was #t (i.e., a
+ catch-all), or the user threw to a jmpbuf.
+ THROW_ARGS is the list of arguments the user passed to the THROW
+ function, after the tag.
+
+ BODY_DATA is just a pointer we pass through to BODY. HANDLER_DATA
+ is just a pointer we pass through to HANDLER. We don't actually
+ use either of those pointers otherwise ourselves. The idea is
+ that, if our caller wants to communicate something to BODY or
+ HANDLER, it can pass a pointer to it as MUMBLE_DATA, which BODY and
+ HANDLER can then use. Think of it as a way to make BODY and
+ HANDLER closures, not just functions; MUMBLE_DATA points to the
+ enclosed variables.
+
+ Of course, it's up to the caller to make sure that any data a
+ MUMBLE_DATA needs is protected from GC. A common way to do this is
+ to make MUMBLE_DATA a pointer to data stored in an automatic
+ structure variable; since the collector must scan the stack for
+ references anyway, this assures that any references in MUMBLE_DATA
+ will be found. */
+
+SCM
+scm_c_catch (SCM tag,
+ scm_t_catch_body body, void *body_data,
+ scm_t_catch_handler handler, void *handler_data,
+ scm_t_catch_handler pre_unwind_handler, void *pre_unwind_handler_data)
+{
+ struct jmp_buf_and_retval jbr;
+ SCM jmpbuf;
+ SCM answer;
+ struct pre_unwind_data pre_unwind;
+
+ jmpbuf = make_jmpbuf ();
+ answer = SCM_EOL;
+ scm_i_set_dynwinds (scm_acons (tag, jmpbuf, scm_i_dynwinds ()));
+ SETJBJMPBUF(jmpbuf, &jbr.buf);
+ SCM_SETJBDFRAME(jmpbuf, scm_i_last_debug_frame ());
+
+ pre_unwind.handler = pre_unwind_handler;
+ pre_unwind.handler_data = pre_unwind_handler_data;
+ pre_unwind.running = 0;
+ pre_unwind.lazy_catch_p = 0;
+ SCM_SETJBPREUNWIND(jmpbuf, &pre_unwind);
+
+ if (setjmp (jbr.buf))
+ {
+ SCM throw_tag;
+ SCM throw_args;
+
+#ifdef STACK_CHECKING
+ scm_stack_checking_enabled_p = SCM_STACK_CHECKING_P;
+#endif
+ SCM_CRITICAL_SECTION_START;
+ DEACTIVATEJB (jmpbuf);
+ scm_i_set_dynwinds (SCM_CDR (scm_i_dynwinds ()));
+ SCM_CRITICAL_SECTION_END;
+ throw_args = jbr.retval;
+ throw_tag = jbr.throw_tag;
+ jbr.throw_tag = SCM_EOL;
+ jbr.retval = SCM_EOL;
+ answer = handler (handler_data, throw_tag, throw_args);
+ }
+ else
+ {
+ ACTIVATEJB (jmpbuf);
+ answer = body (body_data);
+ SCM_CRITICAL_SECTION_START;
+ DEACTIVATEJB (jmpbuf);
+ scm_i_set_dynwinds (SCM_CDR (scm_i_dynwinds ()));
+ SCM_CRITICAL_SECTION_END;
+ }
+ return answer;
+}
+
+SCM
+scm_internal_catch (SCM tag,
+ scm_t_catch_body body, void *body_data,
+ scm_t_catch_handler handler, void *handler_data)
+{
+ return scm_c_catch(tag,
+ body, body_data,
+ handler, handler_data,
+ NULL, NULL);
+}
+
+
+\f
+/* The smob tag for pre_unwind_data smobs. */
+static scm_t_bits tc16_pre_unwind_data;
+
+/* Strictly speaking, we could just pass a zero for our print
+ function, because we don't need to print them. They should never
+ appear in normal data structures, only in the wind list. However,
+ it might be nice for debugging someday... */
+static int
+pre_unwind_data_print (SCM closure, SCM port, scm_print_state *pstate SCM_UNUSED)
+{
+ struct pre_unwind_data *c = (struct pre_unwind_data *) SCM_CELL_WORD_1 (closure);
+ char buf[200];
+
+ sprintf (buf, "#<pre-unwind-data 0x%lx 0x%lx>",
+ (long) c->handler, (long) c->handler_data);
+ scm_puts (buf, port);
+
+ return 1;
+}
+
+
+/* Given a pointer to a pre_unwind_data structure, return a smob for it,
+ suitable for inclusion in the wind list. ("Ah yes, a Château
+ Gollombiere '72, non?"). */
+static SCM
+make_pre_unwind_data (struct pre_unwind_data *c)
+{
+ SCM_RETURN_NEWSMOB (tc16_pre_unwind_data, c);
+}
+
+#define SCM_PRE_UNWIND_DATA_P(obj) (SCM_TYP16_PREDICATE (tc16_pre_unwind_data, obj))
+
+SCM
+scm_c_with_throw_handler (SCM tag,
+ scm_t_catch_body body,
+ void *body_data,
+ scm_t_catch_handler handler,
+ void *handler_data,
+ int lazy_catch_p)
+{
+ SCM pre_unwind, answer;
+ struct pre_unwind_data c;
+
+ c.handler = handler;
+ c.handler_data = handler_data;
+ c.running = 0;
+ c.lazy_catch_p = lazy_catch_p;
+ pre_unwind = make_pre_unwind_data (&c);
+
+ SCM_CRITICAL_SECTION_START;
+ scm_i_set_dynwinds (scm_acons (tag, pre_unwind, scm_i_dynwinds ()));
+ SCM_CRITICAL_SECTION_END;
+
+ answer = (*body) (body_data);
+
+ SCM_CRITICAL_SECTION_START;
+ scm_i_set_dynwinds (SCM_CDR (scm_i_dynwinds ()));
+ SCM_CRITICAL_SECTION_END;
+
+ return answer;
+}
+
+/* Exactly like scm_internal_catch, except:
+ - It does not unwind the stack (this is the major difference).
+ - The handler is not allowed to return. */
+SCM
+scm_internal_lazy_catch (SCM tag, scm_t_catch_body body, void *body_data, scm_t_catch_handler handler, void *handler_data)
+{
+ return scm_c_with_throw_handler (tag, body, body_data, handler, handler_data, 1);
+}
+
+\f
+/* scm_internal_stack_catch
+ Use this one if you want debugging information to be stored in
+ scm_the_last_stack_fluid_var on error. */
+
+static SCM
+ss_handler (void *data SCM_UNUSED, SCM tag, SCM throw_args)
+{
+ /* Save the stack */
+ scm_fluid_set_x (SCM_VARIABLE_REF (scm_the_last_stack_fluid_var),
+ scm_make_stack (SCM_BOOL_T, SCM_EOL));
+ /* Throw the error */
+ return scm_throw (tag, throw_args);
+}
+
+struct cwss_data
+{
+ SCM tag;
+ scm_t_catch_body body;
+ void *data;
+};
+
+static SCM
+cwss_body (void *data)
+{
+ struct cwss_data *d = data;
+ return scm_internal_lazy_catch (d->tag, d->body, d->data, ss_handler, NULL);
+}
+
+SCM
+scm_internal_stack_catch (SCM tag,
+ scm_t_catch_body body,
+ void *body_data,
+ scm_t_catch_handler handler,
+ void *handler_data)
+{
+ struct cwss_data d;
+ d.tag = tag;
+ d.body = body;
+ d.data = body_data;
+ return scm_internal_catch (tag, cwss_body, &d, handler, handler_data);
+}
+
+
+\f
+/* body and handler functions for use with any of the above catch variants */
+
+/* This is a body function you can pass to scm_internal_catch if you
+ want the body to be like Scheme's `catch' --- a thunk.
+
+ BODY_DATA is a pointer to a scm_body_thunk_data structure, which
+ contains the Scheme procedure to invoke as the body, and the tag
+ we're catching. */
+
+SCM
+scm_body_thunk (void *body_data)
+{
+ struct scm_body_thunk_data *c = (struct scm_body_thunk_data *) body_data;
+
+ return scm_call_0 (c->body_proc);
+}
+
+
+/* This is a handler function you can pass to scm_internal_catch if
+ you want the handler to act like Scheme's catch: (throw TAG ARGS ...)
+ applies a handler procedure to (TAG ARGS ...).
+
+ If the user does a throw to this catch, this function runs a
+ handler procedure written in Scheme. HANDLER_DATA is a pointer to
+ an SCM variable holding the Scheme procedure object to invoke. It
+ ought to be a pointer to an automatic variable (i.e., one living on
+ the stack), or the procedure object should be otherwise protected
+ from GC. */
+SCM
+scm_handle_by_proc (void *handler_data, SCM tag, SCM throw_args)
+{
+ SCM *handler_proc_p = (SCM *) handler_data;
+
+ return scm_apply_1 (*handler_proc_p, tag, throw_args);
+}
+
+/* SCM_HANDLE_BY_PROC_CATCHING_ALL is like SCM_HANDLE_BY_PROC but
+ catches all throws that the handler might emit itself. The handler
+ used for these `secondary' throws is SCM_HANDLE_BY_MESSAGE_NO_EXIT. */
+
+struct hbpca_data {
+ SCM proc;
+ SCM args;
+};
+
+static SCM
+hbpca_body (void *body_data)
+{
+ struct hbpca_data *data = (struct hbpca_data *)body_data;
+ return scm_apply_0 (data->proc, data->args);
+}
+
+SCM
+scm_handle_by_proc_catching_all (void *handler_data, SCM tag, SCM throw_args)
+{
+ SCM *handler_proc_p = (SCM *) handler_data;
+ struct hbpca_data data;
+ data.proc = *handler_proc_p;
+ data.args = scm_cons (tag, throw_args);
+
+ return scm_internal_catch (SCM_BOOL_T,
+ hbpca_body, &data,
+ scm_handle_by_message_noexit, NULL);
+}
+
+/* Derive the an exit status from the arguments to (quit ...). */
+int
+scm_exit_status (SCM args)
+{
+ if (!SCM_NULL_OR_NIL_P (args))
+ {
+ SCM cqa = SCM_CAR (args);
+
+ if (scm_is_integer (cqa))
+ return (scm_to_int (cqa));
+ else if (scm_is_false (cqa))
+ return 1;
+ }
+ return 0;
+}
+
+
+static void
+handler_message (void *handler_data, SCM tag, SCM args)
+{
+ char *prog_name = (char *) handler_data;
+ SCM p = scm_current_error_port ();
+
+ if (scm_ilength (args) == 4)
+ {
+ SCM stack = scm_make_stack (SCM_BOOL_T, SCM_EOL);
+ SCM subr = SCM_CAR (args);
+ SCM message = SCM_CADR (args);
+ SCM parts = SCM_CADDR (args);
+ SCM rest = SCM_CADDDR (args);
+
+ if (SCM_BACKTRACE_P && scm_is_true (stack))
+ {
+ SCM highlights;
+
+ if (scm_is_eq (tag, scm_arg_type_key)
+ || scm_is_eq (tag, scm_out_of_range_key))
+ highlights = rest;
+ else
+ highlights = SCM_EOL;
+
+ scm_puts ("Backtrace:\n", p);
+ scm_display_backtrace_with_highlights (stack, p,
+ SCM_BOOL_F, SCM_BOOL_F,
+ highlights);
+ scm_newline (p);
+ }
+ scm_i_display_error (stack, p, subr, message, parts, rest);
+ }
+ else
+ {
+ if (! prog_name)
+ prog_name = "guile";
+
+ scm_puts (prog_name, p);
+ scm_puts (": ", p);
+
+ scm_puts ("uncaught throw to ", p);
+ scm_prin1 (tag, p, 0);
+ scm_puts (": ", p);
+ scm_prin1 (args, p, 1);
+ scm_putc ('\n', p);
+ }
+}
+
+
+/* This is a handler function to use if you want scheme to print a
+ message and die. Useful for dealing with throws to uncaught keys
+ at the top level.
+
+ At boot time, we establish a catch-all that uses this as its handler.
+ 1) If the user wants something different, they can use (catch #t
+ ...) to do what they like.
+ 2) Outside the context of a read-eval-print loop, there isn't
+ anything else good to do; libguile should not assume the existence
+ of a read-eval-print loop.
+ 3) Given that we shouldn't do anything complex, it's much more
+ robust to do it in C code.
+
+ HANDLER_DATA, if non-zero, is assumed to be a char * pointing to a
+ message header to print; if zero, we use "guile" instead. That
+ text is followed by a colon, then the message described by ARGS. */
+
+/* Dirk:FIXME:: The name of the function should make clear that the
+ * application gets terminated.
+ */
+
+SCM
+scm_handle_by_message (void *handler_data, SCM tag, SCM args)
+{
+ if (scm_is_true (scm_eq_p (tag, scm_from_locale_symbol ("quit"))))
+ exit (scm_exit_status (args));
+
+ handler_message (handler_data, tag, args);
+ scm_i_pthread_exit (NULL);
+
+ /* this point not reached, but suppress gcc warning about no return value
+ in case scm_i_pthread_exit isn't marked as "noreturn" (which seemed not
+ to be the case on cygwin for instance) */
+ return SCM_BOOL_F;
+}
+
+
+/* This is just like scm_handle_by_message, but it doesn't exit; it
+ just returns #f. It's useful in cases where you don't really know
+ enough about the body to handle things in a better way, but don't
+ want to let throws fall off the bottom of the wind list. */
+SCM
+scm_handle_by_message_noexit (void *handler_data, SCM tag, SCM args)
+{
+ if (scm_is_true (scm_eq_p (tag, scm_from_locale_symbol ("quit"))))
+ exit (scm_exit_status (args));
+
+ handler_message (handler_data, tag, args);
+
+ return SCM_BOOL_F;
+}
+
+
+SCM
+scm_handle_by_throw (void *handler_data SCM_UNUSED, SCM tag, SCM args)
+{
+ scm_ithrow (tag, args, 1);
+ return SCM_UNSPECIFIED; /* never returns */
+}
+
+
+\f
+/* the Scheme-visible CATCH, WITH-THROW-HANDLER and LAZY-CATCH functions */
+
+SCM_DEFINE (scm_catch_with_pre_unwind_handler, "catch", 3, 1, 0,
+ (SCM key, SCM thunk, SCM handler, SCM pre_unwind_handler),
+ "Invoke @var{thunk} in the dynamic context of @var{handler} for\n"
+ "exceptions matching @var{key}. If thunk throws to the symbol\n"
+ "@var{key}, then @var{handler} is invoked this way:\n"
+ "@lisp\n"
+ "(handler key args ...)\n"
+ "@end lisp\n"
+ "\n"
+ "@var{key} is a symbol or @code{#t}.\n"
+ "\n"
+ "@var{thunk} takes no arguments. If @var{thunk} returns\n"
+ "normally, that is the return value of @code{catch}.\n"
+ "\n"
+ "Handler is invoked outside the scope of its own @code{catch}.\n"
+ "If @var{handler} again throws to the same key, a new handler\n"
+ "from further up the call chain is invoked.\n"
+ "\n"
+ "If the key is @code{#t}, then a throw to @emph{any} symbol will\n"
+ "match this call to @code{catch}.\n"
+ "\n"
+ "If a @var{pre-unwind-handler} is given and @var{thunk} throws\n"
+ "an exception that matches @var{key}, Guile calls the\n"
+ "@var{pre-unwind-handler} before unwinding the dynamic state and\n"
+ "invoking the main @var{handler}. @var{pre-unwind-handler} should\n"
+ "be a procedure with the same signature as @var{handler}, that\n"
+ "is @code{(lambda (key . args))}. It is typically used to save\n"
+ "the stack at the point where the exception occurred, but can also\n"
+ "query other parts of the dynamic state at that point, such as\n"
+ "fluid values.\n"
+ "\n"
+ "A @var{pre-unwind-handler} can exit either normally or non-locally.\n"
+ "If it exits normally, Guile unwinds the stack and dynamic context\n"
+ "and then calls the normal (third argument) handler. If it exits\n"
+ "non-locally, that exit determines the continuation.")
+#define FUNC_NAME s_scm_catch_with_pre_unwind_handler
+{
+ struct scm_body_thunk_data c;
+
+ SCM_ASSERT (scm_is_symbol (key) || scm_is_eq (key, SCM_BOOL_T),
+ key, SCM_ARG1, FUNC_NAME);
+
+ c.tag = key;
+ c.body_proc = thunk;
+
+ /* scm_c_catch takes care of all the mechanics of setting up a catch
+ key; we tell it to call scm_body_thunk to run the body, and
+ scm_handle_by_proc to deal with any throws to this catch. The
+ former receives a pointer to c, telling it how to behave. The
+ latter receives a pointer to HANDLER, so it knows who to
+ call. */
+ return scm_c_catch (key,
+ scm_body_thunk, &c,
+ scm_handle_by_proc, &handler,
+ SCM_UNBNDP (pre_unwind_handler) ? NULL : scm_handle_by_proc,
+ &pre_unwind_handler);
+}
+#undef FUNC_NAME
+
+/* The following function exists to provide backwards compatibility
+ for the C scm_catch API. Otherwise we could just change
+ "scm_catch_with_pre_unwind_handler" above to "scm_catch". */
+SCM
+scm_catch (SCM key, SCM thunk, SCM handler)
+{
+ return scm_catch_with_pre_unwind_handler (key, thunk, handler, SCM_UNDEFINED);
+}
+
+
+SCM_DEFINE (scm_with_throw_handler, "with-throw-handler", 3, 0, 0,
+ (SCM key, SCM thunk, SCM handler),
+ "Add @var{handler} to the dynamic context as a throw handler\n"
+ "for key @var{key}, then invoke @var{thunk}.")
+#define FUNC_NAME s_scm_with_throw_handler
+{
+ struct scm_body_thunk_data c;
+
+ SCM_ASSERT (scm_is_symbol (key) || scm_is_eq (key, SCM_BOOL_T),
+ key, SCM_ARG1, FUNC_NAME);
+
+ c.tag = key;
+ c.body_proc = thunk;
+
+ /* scm_c_with_throw_handler takes care of the mechanics of setting
+ up a throw handler; we tell it to call scm_body_thunk to run the
+ body, and scm_handle_by_proc to deal with any throws to this
+ handler. The former receives a pointer to c, telling it how to
+ behave. The latter receives a pointer to HANDLER, so it knows
+ who to call. */
+ return scm_c_with_throw_handler (key,
+ scm_body_thunk, &c,
+ scm_handle_by_proc, &handler,
+ 0);
+}
+#undef FUNC_NAME
+
+SCM_DEFINE (scm_lazy_catch, "lazy-catch", 3, 0, 0,
+ (SCM key, SCM thunk, SCM handler),
+ "This behaves exactly like @code{catch}, except that it does\n"
+ "not unwind the stack before invoking @var{handler}.\n"
+ "If the @var{handler} procedure returns normally, Guile\n"
+ "rethrows the same exception again to the next innermost catch,\n"
+ "lazy-catch or throw handler. If the @var{handler} exits\n"
+ "non-locally, that exit determines the continuation.")
+#define FUNC_NAME s_scm_lazy_catch
+{
+ struct scm_body_thunk_data c;
+
+ SCM_ASSERT (scm_is_symbol (key) || scm_is_eq (key, SCM_BOOL_T),
+ key, SCM_ARG1, FUNC_NAME);
+
+ c.tag = key;
+ c.body_proc = thunk;
+
+ /* scm_internal_lazy_catch takes care of all the mechanics of
+ setting up a lazy catch key; we tell it to call scm_body_thunk to
+ run the body, and scm_handle_by_proc to deal with any throws to
+ this catch. The former receives a pointer to c, telling it how
+ to behave. The latter receives a pointer to HANDLER, so it knows
+ who to call. */
+ return scm_internal_lazy_catch (key,
+ scm_body_thunk, &c,
+ scm_handle_by_proc, &handler);
+}
+#undef FUNC_NAME
+
+
+\f
+/* throwing */
+
+static void toggle_pre_unwind_running (void *data)
+{
+ struct pre_unwind_data *pre_unwind = (struct pre_unwind_data *)data;
+ pre_unwind->running = !pre_unwind->running;
+}
+
+SCM_DEFINE (scm_throw, "throw", 1, 0, 1,
+ (SCM key, SCM args),
+ "Invoke the catch form matching @var{key}, passing @var{args} to the\n"
+ "@var{handler}. \n\n"
+ "@var{key} is a symbol. It will match catches of the same symbol or of\n"
+ "@code{#t}.\n\n"
+ "If there is no handler at all, Guile prints an error and then exits.")
+#define FUNC_NAME s_scm_throw
+{
+ SCM_VALIDATE_SYMBOL (1, key);
+ return scm_ithrow (key, args, 1);
+}
+#undef FUNC_NAME
+
+SCM
+scm_ithrow (SCM key, SCM args, int noreturn SCM_UNUSED)
+{
+ SCM jmpbuf = SCM_UNDEFINED;
+ SCM wind_goal;
+
+ SCM dynpair = SCM_UNDEFINED;
+ SCM winds;
+
+ if (scm_i_critical_section_level)
+ {
+ SCM s = args;
+ int i = 0;
+
+ /*
+ We have much better routines for displaying Scheme, but we're
+ already inside a pernicious error, and it's unlikely that they
+ are available to us. We try to print something useful anyway,
+ so users don't need a debugger to find out what went wrong.
+ */
+ fprintf (stderr, "throw from within critical section.\n");
+ if (scm_is_symbol (key))
+ fprintf (stderr, "error key: %s\n", scm_i_symbol_chars (key));
+
+
+ for (; scm_is_pair (s); s = scm_cdr (s), i++)
+ if (scm_is_string (scm_car (s)))
+ fprintf (stderr, "argument %d: %s\n", i, scm_i_string_chars (scm_car (s)));
+
+ abort ();
+ }
+
+ rethrow:
+
+ /* Search the wind list for an appropriate catch.
+ "Waiter, please bring us the wind list." */
+ for (winds = scm_i_dynwinds (); scm_is_pair (winds); winds = SCM_CDR (winds))
+ {
+ dynpair = SCM_CAR (winds);
+ if (scm_is_pair (dynpair))
+ {
+ SCM this_key = SCM_CAR (dynpair);
+
+ if (scm_is_eq (this_key, SCM_BOOL_T) || scm_is_eq (this_key, key))
+ {
+ jmpbuf = SCM_CDR (dynpair);
+
+ if (!SCM_PRE_UNWIND_DATA_P (jmpbuf))
+ break;
+ else
+ {
+ struct pre_unwind_data *c =
+ (struct pre_unwind_data *) SCM_CELL_WORD_1 (jmpbuf);
+ if (!c->running)
+ break;
+ }
+ }
+ }
+ }
+
+ /* If we didn't find anything, print a message and abort the process
+ right here. If you don't want this, establish a catch-all around
+ any code that might throw up. */
+ if (scm_is_null (winds))
+ {
+ scm_handle_by_message (NULL, key, args);
+ abort ();
+ }
+
+ /* If the wind list is malformed, bail. */
+ if (!scm_is_pair (winds))
+ abort ();
+
+ for (wind_goal = scm_i_dynwinds ();
+ (!scm_is_pair (SCM_CAR (wind_goal))
+ || !scm_is_eq (SCM_CDAR (wind_goal), jmpbuf));
+ wind_goal = SCM_CDR (wind_goal))
+ ;
+
+ /* Is this a throw handler (or lazy catch)? In a wind list entry
+ for a throw handler or lazy catch, the key is bound to a
+ pre_unwind_data smob, not a jmpbuf. */
+ if (SCM_PRE_UNWIND_DATA_P (jmpbuf))
+ {
+ struct pre_unwind_data *c =
+ (struct pre_unwind_data *) SCM_CELL_WORD_1 (jmpbuf);
+ SCM handle, answer;
+
+ /* For old-style lazy-catch behaviour, we unwind the dynamic
+ context before invoking the handler. */
+ if (c->lazy_catch_p)
+ {
+ scm_dowinds (wind_goal, (scm_ilength (scm_i_dynwinds ())
+ - scm_ilength (wind_goal)));
+ SCM_CRITICAL_SECTION_START;
+ handle = scm_i_dynwinds ();
+ scm_i_set_dynwinds (SCM_CDR (handle));
+ SCM_CRITICAL_SECTION_END;
+ }
+
+ /* Call the handler, with framing to set the pre-unwind
+ structure's running field while the handler is running, so we
+ can avoid recursing into the same handler again. Note that
+ if the handler returns normally, the running flag stays
+ set until some kind of non-local jump occurs. */
+ scm_dynwind_begin (SCM_F_DYNWIND_REWINDABLE);
+ scm_dynwind_rewind_handler (toggle_pre_unwind_running,
+ c,
+ SCM_F_WIND_EXPLICITLY);
+ scm_dynwind_unwind_handler (toggle_pre_unwind_running, c, 0);
+ answer = (c->handler) (c->handler_data, key, args);
+
+ /* There is deliberately no scm_dynwind_end call here. This
+ means that the unwind handler (toggle_pre_unwind_running)
+ stays in place until a non-local exit occurs, and will then
+ reset the pre-unwind structure's running flag. For sample
+ code where this makes a difference, see the "again but with
+ two chained throw handlers" test case in exceptions.test. */
+
+ /* If the handler returns, rethrow the same key and args. */
+ goto rethrow;
+ }
+
+ /* Otherwise, it's a normal catch. */
+ else if (SCM_JMPBUFP (jmpbuf))
+ {
+ struct pre_unwind_data * pre_unwind;
+ struct jmp_buf_and_retval * jbr;
+
+ /* Before unwinding anything, run the pre-unwind handler if
+ there is one, and if it isn't already running. */
+ pre_unwind = SCM_JBPREUNWIND (jmpbuf);
+ if (pre_unwind->handler && !pre_unwind->running)
+ {
+ /* Use framing to detect and avoid possible reentry into
+ this handler, which could otherwise cause an infinite
+ loop. */
+ scm_dynwind_begin (SCM_F_DYNWIND_REWINDABLE);
+ scm_dynwind_rewind_handler (toggle_pre_unwind_running,
+ pre_unwind,
+ SCM_F_WIND_EXPLICITLY);
+ scm_dynwind_unwind_handler (toggle_pre_unwind_running,
+ pre_unwind,
+ SCM_F_WIND_EXPLICITLY);
+ (pre_unwind->handler) (pre_unwind->handler_data, key, args);
+ scm_dynwind_end ();
+ }
+
+ /* Now unwind and jump. */
+ scm_dowinds (wind_goal, (scm_ilength (scm_i_dynwinds ())
+ - scm_ilength (wind_goal)));
+ jbr = (struct jmp_buf_and_retval *)JBJMPBUF (jmpbuf);
+ jbr->throw_tag = key;
+ jbr->retval = args;
+ scm_i_set_last_debug_frame (SCM_JBDFRAME (jmpbuf));
+ longjmp (*JBJMPBUF (jmpbuf), 1);
+ }
+
+ /* Otherwise, it's some random piece of junk. */
+ else
+ abort ();
+}
+
+
+void
+scm_init_throw ()
+{
+ tc16_jmpbuffer = scm_make_smob_type ("jmpbuffer", 0);
+ scm_set_smob_print (tc16_jmpbuffer, jmpbuffer_print);
+
+ tc16_pre_unwind_data = scm_make_smob_type ("pre-unwind-data", 0);
+ scm_set_smob_print (tc16_pre_unwind_data, pre_unwind_data_print);
+
+#include "libguile/throw.x"
+}
+
+/*
+ Local Variables:
+ c-file-style: "gnu"
+ End:
+*/
HCoop / bpt / guile.git / blobdiff