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add another argument to `{chaperone,impersonate}-prompt-tag'

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The new argument gets to chaperone/impersonate a guard at
the prompt, and it is applied when the continuation is applied ---
based on a wrapper on th prompt tag of the continuation (as opposed to
the prompt tag of the prompt).
This commit is contained in:
Matthew Flatt 2012-10-17 10:07:08 -06:00
parent a86f1751bc
commit 04e8689a9b
5 changed files with 398 additions and 105 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

30
collects/scribblings/reference/chaperones.scrbl
View File

@ -333,7 +333,8 @@ or override impersonator-property values of @racket[hash].}
@defproc[(impersonate-prompt-tag [prompt-tag continuation-prompt-tag?]
[handle-proc procedure?]
[abort-proc procedure?]
[callcc-guard-proc procedure? values]
[cc-guard-proc procedure? values]
[callcc-impersonate-proc (procedure? . -> . procedure?) (lambda (p) p)]
[prop impersonator-property?]
[prop-val any] ... ...)
(and/c continuation-prompt-tag? impersonator?)]{
@ -350,7 +351,7 @@ The @racket[abort-proc] must accept the values passed to
@racket[abort-current-continuation]; it must produce replacement
values, which are aborted to the appropriate prompt.
The @racket[callcc-guard-proc] must accept the values produced by
The @racket[cc-guard-proc] must accept the values produced by
@racket[call-with-continuation-prompt] in the case that a
non-composable continuation is applied to replace the continuation
that is delimited by the prompt, but only if
@ -358,6 +359,22 @@ that is delimited by the prompt, but only if
continuation delimited by the prompt (in which case
@racket[abort-proc] is used).
The @racket[callcc-impersonate-proc] must accept a procedure that
guards the result of a continuation captured by
@racket[call-with-current-continuation] with the impersonated prompt
tag. The @racket[callcc-impersonate-proc] is applied (under a
@tech{continuation barrier}) when the captured continuation is applied
to refine a guard function (initially @racket[values]) that is
specific to the delimiting prompt; this prompt-specific guard is
ultimately composed with any @racket[cc-guard-proc] that is in effect
at the delimiting prompt, and it is not used in the same case that a
@racket[cc-guard-proc] is not used (i.e., when
@racket[abort-current-continuation] is used to abort to the
prompt). In the special case where the delimiting prompt at
application time is a thread's built-in initial prompt,
@racket[callcc-impersonate-proc] is ignored (partly on the grounds
that the initial prompt's result is ignored).
Pairs of @racket[prop] and @racket[prop-val] (the number of arguments
to @racket[impersonate-prompt-tag] must be odd) add impersonator properties
or override impersonator-property values of @racket[prompt-tag].
@ -613,7 +630,8 @@ or override impersonator-property values of @racket[evt].}
@defproc[(chaperone-prompt-tag [prompt-tag continuation-prompt-tag?]
[handle-proc procedure?]
[abort-proc procedure?]
[callcc-guard-proc procedure? values]
[cc-guard-proc procedure? values]
[callcc-chaperone-proc (procedure? . -> . procedure?) (lambda (p) p)]
[prop impersonator-property?]
[prop-val any] ... ...)
(and/c continuation-prompt-tag? chaperone?)]{
@ -622,8 +640,10 @@ Like @racket[impersonate-prompt-tag], but produces a chaperoned value.
The @racket[handle-proc] procedure must produce the same values or
chaperones of the original values, @racket[abort-proc] must produce
the same values or chaperones of the values that it is given, and
@racket[callcc-guard--proc] must produce
the same values or chaperones of the original result values.
@racket[cc-guard-proc] must produce the same values or chaperones of
the original result values, and @racket[callcc-chaperone-proc] must
procedure a procedure that is a chaperone or the same as the given
procedure.
@examples[
(define bad-chaperone

85
collects/tests/racket/prompt.rktl
View File

@ -284,6 +284,91 @@
(lambda (x i v) v)))))
v)))
(let ()
(define abort-k/y
(call-with-continuation-prompt
(lambda ()
(call/cc (lambda (k) k)
(impersonate-prompt-tag (default-continuation-prompt-tag)
values
values
values
(lambda (proc)
(lambda (v) (string-append v "y"))))))))
(test
"sy"
call-with-continuation-prompt
(lambda ()
(+ 1 (abort-k/y "s")))))
(let ()
(define really-abort-k
(call-with-continuation-prompt
(lambda ()
(call/cc (lambda (k) (abort-current-continuation
(default-continuation-prompt-tag)
(lambda () k))))
(abort-current-continuation
(default-continuation-prompt-tag)
(lambda () "a")))))
(test
"a"
call-with-continuation-prompt
(lambda ()
(+ 1 (really-abort-k "s")))
(impersonate-prompt-tag (default-continuation-prompt-tag)
values
values
(lambda (s) (string-append s "x")))))
;; ----------------------------------------
;; Check that when a continuation includes a continuation
;; application, that a captured requirement to apply a
;; contiuation-result guard (as added by an impersonator) is not
;; influenced by canceling the guard in a different use of the
;; continuation.
(let ()
(define other-tag
(make-continuation-prompt-tag))
(define other-k #f)
(define wacky-abort-k
(call-with-continuation-prompt
(lambda ()
(define r
(call/cc (lambda (k) (abort-current-continuation
(default-continuation-prompt-tag)
(lambda () k)))))
(when (call/cc (lambda (k)
(set! other-k k)
#t)
other-tag)
(abort-current-continuation
(default-continuation-prompt-tag)
(lambda () "a")))
r)))
(test
"sx"
call-with-continuation-prompt
(lambda ()
(define str
(call-with-continuation-prompt
(lambda ()
(+ 1 (wacky-abort-k "s")))
(impersonate-prompt-tag (default-continuation-prompt-tag)
values
values
(lambda (s) (string-append s "x")))))
(if (equal? str "a")
(other-k #f)
str))
other-tag))
;;----------------------------------------
(report-errs)

32
src/racket/src/eval.c
View File

@ -1379,9 +1379,14 @@ static Scheme_Prompt *lookup_cont_prompt(Scheme_Cont *c,
const char *msg)
{
Scheme_Prompt *prompt;
Scheme_Object *pt;
prompt = scheme_get_prompt(SCHEME_PTR_VAL(c->prompt_tag), _prompt_mc, _prompt_pos);
if (!prompt && !SAME_OBJ(scheme_default_prompt_tag, c->prompt_tag)) {
pt = c->prompt_tag;
if (SCHEME_NP_CHAPERONEP(pt))
pt = SCHEME_CHAPERONE_VAL(pt);
prompt = scheme_get_prompt(SCHEME_PTR_VAL(pt), _prompt_mc, _prompt_pos);
if (!prompt && !SAME_OBJ(scheme_default_prompt_tag, pt)) {
scheme_raise_exn(MZEXN_FAIL_CONTRACT_CONTINUATION, msg);
}
@ -1446,6 +1451,7 @@ static int exec_dyn_wind_posts(Scheme_Dynamic_Wind *common, Scheme_Cont *c, int
Scheme_Thread *p = scheme_current_thread;
Scheme_Dynamic_Wind *dw;
int old_cac = scheme_continuation_application_count;
Scheme_Object *pt;
*_common = common;
@ -1481,7 +1487,11 @@ static int exec_dyn_wind_posts(Scheme_Dynamic_Wind *common, Scheme_Cont *c, int
if (scheme_continuation_application_count != old_cac) {
old_cac = scheme_continuation_application_count;
common = intersect_dw(p->dw, c->dw, c->prompt_tag, c->has_prompt_dw, &common_depth);
pt = c->prompt_tag;
if (SCHEME_NP_CHAPERONEP(pt))
pt = SCHEME_CHAPERONE_VAL(pt);
common = intersect_dw(p->dw, c->dw, pt, c->has_prompt_dw, &common_depth);
*_common = common;
}
} else
@ -1544,6 +1554,7 @@ Scheme_Object *scheme_jump_to_continuation(Scheme_Object *obj, int num_rands, Sc
/* Aborting (Scheme-style) continuation. */
int orig_cac = scheme_continuation_application_count;
Scheme_Overflow *thread_end_oflow;
Scheme_Object *pt;
scheme_about_to_move_C_stack();
@ -1552,10 +1563,14 @@ Scheme_Object *scheme_jump_to_continuation(Scheme_Object *obj, int num_rands, Sc
p->suspend_break++; /* restored at call/cc destination */
pt = c->prompt_tag;
if (SCHEME_NP_CHAPERONEP(pt))
pt = SCHEME_CHAPERONE_VAL(pt);
/* Find `common', the intersection of dynamic-wind chain for
the current continuation and the given continuation, looking
no further back in the current continuation than a prompt. */
common = intersect_dw(p->dw, c->dw, c->prompt_tag, c->has_prompt_dw, &common_depth);
common = intersect_dw(p->dw, c->dw, pt, c->has_prompt_dw, &common_depth);
/* For dynamic-winds after `common' in this
continuation, execute the post-thunks */
@ -1590,9 +1605,6 @@ Scheme_Object *scheme_jump_to_continuation(Scheme_Object *obj, int num_rands, Sc
scheme_continuation_application_count++;
if (prompt)
prompt->needs_cc_guard = 1;
if (!prompt) {
/* Invoke the continuation directly. If there's no prompt,
then the prompt's job is taken by the pseudo-prompt
@ -1617,7 +1629,7 @@ Scheme_Object *scheme_jump_to_continuation(Scheme_Object *obj, int num_rands, Sc
&& !prompt_mc) {
/* The current prompt is the same as the one in place when
capturing the continuation, so we can jump directly. */
scheme_drop_prompt_meta_continuations(c->prompt_tag);
scheme_drop_prompt_meta_continuations(pt);
c->shortcut_prompt = prompt;
if ((!prompt->boundary_overflow_id && !p->overflow)
|| (prompt->boundary_overflow_id
@ -1685,12 +1697,12 @@ Scheme_Object *scheme_jump_to_continuation(Scheme_Object *obj, int num_rands, Sc
if (p->meta_continuation->pseudo)
scheme_signal_error("internal error: trying to jump to a prompt in a meta-cont"
" that starts with a pseudo prompt");
scheme_drop_prompt_meta_continuations(c->prompt_tag);
scheme_drop_prompt_meta_continuations(pt);
scheme_longjmp(*prompt->prompt_buf, 1);
} else {
/* Need to unwind overflows to get to the prompt. */
Scheme_Overflow *overflow;
scheme_drop_prompt_meta_continuations(c->prompt_tag);
scheme_drop_prompt_meta_continuations(pt);
overflow = p->overflow;
while (overflow->prev
&& (!overflow->prev->id

354
src/racket/src/fun.c
View File

@ -102,6 +102,7 @@ ROSYM static Scheme_Object *none_symbol;
ROSYM static Scheme_Object *is_method_symbol;
ROSYM static Scheme_Object *cont_key; /* uninterned */
ROSYM static Scheme_Object *barrier_prompt_key; /* uninterned */
ROSYM static Scheme_Object *prompt_cc_guard_key; /* uninterned */
READ_ONLY static Scheme_Prompt *original_default_prompt; /* for escapes, represents the implicit initial prompt */
READ_ONLY static Scheme_Object *call_with_prompt_proc;
READ_ONLY static Scheme_Object *abort_continuation_proc;
@ -186,10 +187,19 @@ static Scheme_Object *current_prompt_read(int, Scheme_Object **);
static Scheme_Object *current_read(int, Scheme_Object **);
static Scheme_Object *current_get_read_input_port(int, Scheme_Object **);
static Scheme_Object *chaperone_wrap_cc_guard(Scheme_Object *obj, Scheme_Object *proc);
static Scheme_Object *do_cc_guard(Scheme_Object *v, Scheme_Object *cc_guard, Scheme_Object *chaperone);
static Scheme_Object *
scheme_extract_one_cc_mark_with_meta(Scheme_Object *mark_set, Scheme_Object *key,
Scheme_Object *prompt_tag, Scheme_Meta_Continuation **_meta,
MZ_MARK_POS_TYPE *_vpos);
static Scheme_Object *get_set_cont_mark_by_pos(Scheme_Object *key,
Scheme_Thread *p,
Scheme_Meta_Continuation *mc,
MZ_MARK_POS_TYPE mpos,
Scheme_Object *val);
static Scheme_Object *jump_to_alt_continuation();
static void reset_cjs(Scheme_Continuation_Jump_State *a);
@ -633,10 +643,12 @@ scheme_init_fun (Scheme_Env *env)
REGISTER_SO(scheme_inferred_name_symbol);
REGISTER_SO(cont_key);
REGISTER_SO(barrier_prompt_key);
REGISTER_SO(prompt_cc_guard_key);
is_method_symbol = scheme_intern_symbol("method-arity-error");
scheme_inferred_name_symbol = scheme_intern_symbol("inferred-name");
cont_key = scheme_make_symbol("k"); /* uninterned */
barrier_prompt_key = scheme_make_symbol("bar"); /* uninterned */
prompt_cc_guard_key = scheme_make_symbol("cc"); /* uninterned */
REGISTER_SO(scheme_default_prompt_tag);
{
@ -1125,7 +1137,6 @@ void *scheme_top_level_do_worker(void *(*k)(void), int eb, int new_thread, Schem
void *external_stack;
#endif
if (scheme_active_but_sleeping)
scheme_wake_up();
@ -4784,14 +4795,11 @@ call_cc (int argc, Scheme_Object *argv[])
scheme_check_proc_arity("call-with-current-continuation", 1,
0, argc, argv);
if (argc > 1) {
if (!SAME_TYPE(scheme_prompt_tag_type, SCHEME_TYPE(argv[1]))) {
if (SCHEME_NP_CHAPERONEP(argv[1])
&& SCHEME_PROMPT_TAGP(SCHEME_CHAPERONE_VAL(argv[1])))
argv[1] = SCHEME_CHAPERONE_VAL(argv[1]);
else
scheme_wrong_contract("call-with-current-continuation", "continuation-prompt-tag?",
1, argc, argv);
}
if (!SAME_TYPE(scheme_prompt_tag_type, SCHEME_TYPE(argv[1]))
&& !((SCHEME_NP_CHAPERONEP(argv[1])
&& SCHEME_PROMPT_TAGP(SCHEME_CHAPERONE_VAL(argv[1])))))
scheme_wrong_contract("call-with-current-continuation", "continuation-prompt-tag?",
1, argc, argv);
}
/* Trampoline to internal_call_cc. This trampoline ensures that
@ -4800,7 +4808,7 @@ call_cc (int argc, Scheme_Object *argv[])
}
static Scheme_Cont *grab_continuation(Scheme_Thread *p, int for_prompt, int composable,
Scheme_Object *prompt_tag,
Scheme_Object *prompt_tag, Scheme_Object *pt,
Scheme_Cont *sub_cont, Scheme_Prompt *prompt,
Scheme_Meta_Continuation *prompt_cont,
Scheme_Prompt *effective_barrier_prompt
@ -4831,7 +4839,7 @@ static Scheme_Cont *grab_continuation(Scheme_Thread *p, int for_prompt, int comp
else if (prompt) {
Scheme_Dynamic_Wind *dw;
if (p->dw) {
dw = clone_dyn_wind(p->dw, prompt_tag, -1, -1, NULL, 0, composable);
dw = clone_dyn_wind(p->dw, pt, -1, -1, NULL, 0, composable);
cont->dw = dw;
cont->next_meta = p->next_meta;
} else
@ -4856,7 +4864,7 @@ static Scheme_Cont *grab_continuation(Scheme_Thread *p, int for_prompt, int comp
} else if (prompt) {
Scheme_Meta_Continuation *mc;
Scheme_Object *id;
mc = clone_meta_cont(p->meta_continuation, prompt_tag, -1, prompt_cont, prompt, NULL, composable);
mc = clone_meta_cont(p->meta_continuation, pt, -1, prompt_cont, prompt, NULL, composable);
cont->meta_continuation = mc;
if (!prompt_cont) {
/* Remember the prompt id, so we can maybe take a shortcut on
@ -5334,7 +5342,7 @@ static void restore_continuation(Scheme_Cont *cont, Scheme_Thread *p, int for_pr
static Scheme_Object *
internal_call_cc (int argc, Scheme_Object *argv[])
{
Scheme_Object *ret, * volatile prompt_tag;
Scheme_Object *ret, * volatile pt, * prompt_tag;
Scheme_Cont * volatile cont;
Scheme_Cont *sub_cont;
Scheme_Meta_Continuation *prompt_cont, *barrier_cont;
@ -5350,10 +5358,15 @@ internal_call_cc (int argc, Scheme_Object *argv[])
else
prompt_tag = scheme_default_prompt_tag;
if (SCHEME_NP_CHAPERONEP(prompt_tag))
pt = SCHEME_CHAPERONE_VAL(prompt_tag);
else
pt = prompt_tag;
composable = (argc > 2);
prompt = scheme_get_prompt(SCHEME_PTR_VAL(prompt_tag), &prompt_cont, &prompt_pos);
if (!prompt && !SAME_OBJ(scheme_default_prompt_tag, prompt_tag)) {
prompt = scheme_get_prompt(SCHEME_PTR_VAL(pt), &prompt_cont, &prompt_pos);
if (!prompt && !SAME_OBJ(scheme_default_prompt_tag, pt)) {
scheme_contract_error((composable
? "call-with-composable-continuation"
: "call-with-current-continuation"),
@ -5470,7 +5483,7 @@ internal_call_cc (int argc, Scheme_Object *argv[])
return _scheme_tail_apply(argv[0], 1, argv2);
}
cont = grab_continuation(p, 0, composable, prompt_tag, sub_cont,
cont = grab_continuation(p, 0, composable, prompt_tag, pt, sub_cont,
prompt, prompt_cont, effective_barrier_prompt);
scheme_zero_unneeded_rands(p);
@ -5570,7 +5583,7 @@ internal_call_cc (int argc, Scheme_Object *argv[])
cont->empty_to_next_mc = 0;
restore_continuation(cont, p, 0, result, resume, empty_to_next_mc,
prompt_tag, sub_cont,
pt, sub_cont,
common_dw, common_next_meta, shortcut_prompt,
!!resume, 1,
use_next_cont, extra_marks);
@ -5595,6 +5608,24 @@ internal_call_cc (int argc, Scheme_Object *argv[])
p->acting_barrier_prompt = acting_barrier_prompt;
}
{
Scheme_Meta_Continuation *mc;
MZ_MARK_POS_TYPE pos;
Scheme_Object *cc_guard;
prompt = scheme_get_prompt(SCHEME_PTR_VAL(pt), &mc, &pos);
if (prompt && (prompt->has_chaperone || SCHEME_NP_CHAPERONEP(cont->prompt_tag))) {
cc_guard = get_set_cont_mark_by_pos(prompt_cc_guard_key, p, mc, pos, NULL);
if (SCHEME_FALSEP(cc_guard))
cc_guard = scheme_values_func;
if (SCHEME_NP_CHAPERONEP(cont->prompt_tag))
cc_guard = chaperone_wrap_cc_guard(cont->prompt_tag, cc_guard);
get_set_cont_mark_by_pos(prompt_cc_guard_key, p, mc, pos, cc_guard);
}
}
return result;
} else if (composable || cont->escape_cont) {
Scheme_Object *argv2[1];
@ -5758,15 +5789,22 @@ Scheme_Object *do_chaperone_prompt_tag (const char *name, int is_impersonator, i
if (!SCHEME_PROCP(argv[2]))
scheme_wrong_contract(name, "procedure?", 2, argc, argv);
redirects = argv[2];
if ((argc > 3) && !SCHEME_CHAPERONEP(argv[3])) {
if (!SCHEME_PROCP(argv[3]))
scheme_wrong_contract(name, "(or/c procedure? impersonator-property?)", 3, argc, argv);
redirects = scheme_make_pair(redirects, argv[3]);
ppos = 4;
} else
redirects = argv[3];
if ((argc > 4) && !SCHEME_CHAPERONEP(argv[4])) {
if (!scheme_check_proc_arity(NULL, 1, 4, argc, argv))
scheme_wrong_contract(name, "(or/c (procedure-arity-includes/c 1) impersonator-property?)", 4, argc, argv);
redirects = scheme_make_pair(redirects, argv[4]);
ppos = 5;
} else
ppos = 4;
redirects = scheme_make_pair(argv[1], redirects);
} else {
ppos = 3;
redirects = argv[2];
}
redirects = scheme_make_pair(argv[1], redirects);
@ -5998,7 +6036,7 @@ static Scheme_Object *compose_continuation(Scheme_Cont *cont, int exec_chain,
/* Grab a continuation so that we capture the current Scheme stack,
etc.: */
saved = grab_continuation(p, 1, 0, NULL, NULL, NULL, NULL, NULL);
saved = grab_continuation(p, 1, 0, NULL, NULL, NULL, NULL, NULL, NULL);
if (p->meta_prompt)
saved->prompt_stack_start = p->meta_prompt->stack_boundary;
@ -6199,39 +6237,56 @@ static void prompt_unwind_one_dw(Scheme_Object *prompt_tag)
prompt_unwind_dw(prompt_tag);
}
static Scheme_Object **chaperone_do_control(const char *name, int mode, Scheme_Object *obj,
static Scheme_Object **chaperone_do_control(const char *name, int mode,
Scheme_Object *init_guard, Scheme_Object *obj,
int argc, Scheme_Object **argv)
{
Scheme_Chaperone *px;
Scheme_Object **vals = NULL;
Scheme_Object **vals = argv;
Scheme_Object *v;
Scheme_Object *proc;
int i, num_args;
while (1) {
if (SCHEME_PROMPT_TAGP(obj)) {
return vals;
} else {
px = (Scheme_Chaperone *)obj;
obj = px->prev;
if (init_guard || !SCHEME_PROMPT_TAGP(obj)) {
if (init_guard) {
proc = init_guard;
if (SAME_OBJ(NULL, scheme_values_func))
proc = NULL;
} else {
px = (Scheme_Chaperone *)obj;
obj = px->prev;
if (!mode)
proc = SCHEME_CAR(px->redirects);
else {
proc = SCHEME_CDR(px->redirects);
if (mode == 1) {
if (SCHEME_PAIRP(proc))
proc = SCHEME_CAR(proc);
} else {
if (SCHEME_PAIRP(proc))
proc = SCHEME_CDR(proc);
else
proc = NULL;
if (!mode)
proc = SCHEME_CAR(px->redirects);
else {
proc = SCHEME_CDR(px->redirects);
if (mode == 1) {
if (SCHEME_PAIRP(proc))
proc = SCHEME_CAR(proc);
} else {
if (SCHEME_PAIRP(proc)) {
proc = SCHEME_CDR(proc);
if (mode == 2) {
if (SCHEME_PAIRP(proc))
proc = SCHEME_CAR(proc);
} else {
if (SCHEME_PAIRP(proc))
proc = SCHEME_CDR(proc);
else
proc = NULL;
}
} else
proc = NULL;
}
}
}
if (proc) {
v = _scheme_apply_multi(proc, argc, argv);
if (mode == 3)
v = scheme_apply(proc, argc, argv); /* with barrier */
else
v = _scheme_apply_multi(proc, argc, argv);
if (v == SCHEME_MULTIPLE_VALUES) {
GC_CAN_IGNORE Scheme_Thread *p = scheme_current_thread;
@ -6254,31 +6309,81 @@ static Scheme_Object **chaperone_do_control(const char *name, int mode, Scheme_O
else if (num_args != argc)
scheme_wrong_return_arity(name, argc, num_args, vals, "use of redirecting procedure");
if (!(SCHEME_CHAPERONE_FLAGS(px) & SCHEME_CHAPERONE_IS_IMPERSONATOR)) {
for (i = 0; i < argc; i++) {
if (!scheme_chaperone_of(vals[i], argv[i]))
scheme_wrong_chaperoned(name, "value", argv[i], vals[i]);
argv[i] = vals[i];
if (mode == 3) {
if (!scheme_check_proc_arity(NULL, 1, 0, argc, vals)) {
scheme_wrong_type("call/cc guard-wrapping function", "(procedure-arity-includes/c 2)", 0, -1, vals);
}
}
if (!init_guard) {
if (!(SCHEME_CHAPERONE_FLAGS(px) & SCHEME_CHAPERONE_IS_IMPERSONATOR)) {
for (i = 0; i < argc; i++) {
if (!scheme_chaperone_of(vals[i], argv[i]))
scheme_wrong_chaperoned(name, "value", argv[i], vals[i]);
}
}
}
argv = vals;
}
init_guard = NULL;
} else {
return vals;
}
}
}
static Scheme_Object **chaperone_do_prompt_handler(Scheme_Object *obj, int argc, Scheme_Object **argv)
{
return chaperone_do_control("call-with-continuation-prompt", 0, obj, argc, argv);
return chaperone_do_control("call-with-continuation-prompt", 0, NULL, obj, argc, argv);
}
static Scheme_Object **chaperone_do_abort(Scheme_Object *obj, int argc, Scheme_Object **argv)
{
return chaperone_do_control("abort-current-continuation", 1, obj, argc, argv);
return chaperone_do_control("abort-current-continuation", 1, NULL, obj, argc, argv);
}
static Scheme_Object **chaperone_do_cc_guard(Scheme_Object *obj, int argc, Scheme_Object **argv)
static Scheme_Object **chaperone_do_cc_guard(Scheme_Object *cc_guard, Scheme_Object *obj, int argc, Scheme_Object **argv)
{
return chaperone_do_control("call-with-continuation-prompt", 2, obj, argc, argv);
return chaperone_do_control("call-with-continuation-prompt", 2, cc_guard, obj, argc, argv);
}
static Scheme_Object *chaperone_wrap_cc_guard(Scheme_Object *obj, Scheme_Object *proc)
{
Scheme_Object *a[1], **a2;
a[0] = proc;
a2 = chaperone_do_control("call-with-current-continuation", 3, NULL, obj, 1, a);
return a2[0];
}
static Scheme_Object *do_cc_guard(Scheme_Object *v, Scheme_Object *cc_guard, Scheme_Object *chaperone)
{
int argc;
Scheme_Object **argv, *a[1];
if (v == SCHEME_MULTIPLE_VALUES) {
GC_CAN_IGNORE Scheme_Thread *p = scheme_current_thread;
if (SAME_OBJ(p->ku.multiple.array, p->values_buffer))
p->values_buffer = NULL;
argc = p->ku.multiple.count;
argv = p->ku.multiple.array;
} else {
a[0] = v;
argv = a;
argc = 1;
}
if (!chaperone) chaperone = scheme_default_prompt_tag;
argv = chaperone_do_cc_guard(cc_guard, chaperone, argc, argv);
if (argc == 1)
return argv[0];
else
return scheme_values(argc, argv);
}
static Scheme_Object *call_with_prompt (int in_argc, Scheme_Object *in_argv[])
@ -6293,8 +6398,7 @@ static Scheme_Object *call_with_prompt (int in_argc, Scheme_Object *in_argv[])
Scheme_Cont_Frame_Data cframe;
Scheme_Dynamic_Wind *prompt_dw;
int cc_count = scheme_cont_capture_count;
Scheme_Object *chaperone = NULL;
int needs_cc_guard = 0;
Scheme_Object *chaperone = NULL, *cc_guard = scheme_false;
argc = in_argc - 3;
if (argc <= 0) {
@ -6352,7 +6456,18 @@ static Scheme_Object *call_with_prompt (int in_argc, Scheme_Object *in_argv[])
prompt->tag = prompt_tag;
/* An abuse of the continuation-mark stack: to keep track of
chaperoning guards on a continuation result, we mutate a mark
that is keyed on prompt_cc_mark_key and that sits next to the
prompt mark. This is an abuse, because marks are not supposed
to be mutable, but we do that to keep the mark setting attached
to a continuation (given that continuation marks are copied out
and in for a saved and restored continuation). We don't run
afoul of caching, which depends on immuatbility of marks,
because we access the mark only by get_set_cont_mark_by_pos(). */
scheme_push_continuation_frame(&cframe);
scheme_set_cont_mark(prompt_cc_guard_key, cc_guard); /* see "abuse" note above */
scheme_set_cont_mark(SCHEME_PTR_VAL(prompt_tag), (Scheme_Object *)prompt);
/* Note: prompt save marks after the one corresponding to itself,
@ -6388,6 +6503,8 @@ static Scheme_Object *call_with_prompt (int in_argc, Scheme_Object *in_argv[])
p->next_meta = 0;
p->dw = prompt_dw;
if (chaperone)
prompt->has_chaperone = 1;
v = scheme_apply_for_prompt(prompt, prompt_tag, proc, argc, argv);
@ -6466,8 +6583,8 @@ static Scheme_Object *call_with_prompt (int in_argc, Scheme_Object *in_argv[])
delivered a value. */
if (!v) {
prompt->needs_cc_guard = 0;
needs_cc_guard = 0; /* cancel any pending check */
/* cancel any pending cc_guard: */
get_set_cont_mark_by_pos(prompt_cc_guard_key, p, NULL, MZ_CONT_MARK_POS, scheme_false);
argc = p->cjs.num_vals;
@ -6529,10 +6646,10 @@ static Scheme_Object *call_with_prompt (int in_argc, Scheme_Object *in_argv[])
argv = NULL;
}
scheme_pop_continuation_frame(&cframe);
cc_guard = get_set_cont_mark_by_pos(prompt_cc_guard_key, p, NULL, MZ_CONT_MARK_POS, NULL);
if (SCHEME_FALSEP(cc_guard)) cc_guard = NULL;
if (prompt->needs_cc_guard)
needs_cc_guard = 1;
scheme_pop_continuation_frame(&cframe);
if (cc_count == scheme_cont_capture_count) {
if (!available_regular_prompt) {
@ -6561,23 +6678,13 @@ static Scheme_Object *call_with_prompt (int in_argc, Scheme_Object *in_argv[])
if (handler) {
return _scheme_tail_apply(handler, argc, argv);
} else if (needs_cc_guard && chaperone) {
if (v == SCHEME_MULTIPLE_VALUES) {
GC_CAN_IGNORE Scheme_Thread *p = scheme_current_thread;
if (SAME_OBJ(p->ku.multiple.array, p->values_buffer))
p->values_buffer = NULL;
argc = p->ku.multiple.count;
argv = p->ku.multiple.array;
} else {
a[0] = v;
argv = a;
argc = 1;
}
argv = chaperone_do_cc_guard(chaperone, argc, argv);
if (argc == 1)
return argv[0];
} else if (cc_guard) {
if (SAME_OBJ(cc_guard, scheme_values_func))
cc_guard = NULL;
if (cc_guard || chaperone)
return do_cc_guard(v, cc_guard, chaperone);
else
return scheme_values(argc, argv);
return v;
} else
return v;
}
@ -6836,17 +6943,17 @@ static Scheme_Object *do_call_with_control (int argc, Scheme_Object *argv[], int
scheme_check_proc_arity("call-with-composable-continuation", 1, 0, argc, argv);
if (argc > 1) {
if (!SAME_TYPE(scheme_prompt_tag_type, SCHEME_TYPE(argv[1]))) {
if (SCHEME_NP_CHAPERONEP(argv[1])
&& SCHEME_PROMPT_TAGP(SCHEME_CHAPERONE_VAL(argv[1])))
prompt_tag = SCHEME_CHAPERONE_VAL(argv[1]);
prompt_tag = argv[1];
if (!SAME_TYPE(scheme_prompt_tag_type, SCHEME_TYPE(prompt_tag))) {
if (SCHEME_NP_CHAPERONEP(prompt_tag)
&& SCHEME_PROMPT_TAGP(SCHEME_CHAPERONE_VAL(prompt_tag)))
prompt_tag = SCHEME_CHAPERONE_VAL(prompt_tag);
else {
scheme_wrong_contract("call-with-composable-continuation", "continuation-prompt-tag?",
1, argc, argv);
return NULL;
}
} else
prompt_tag = argv[1];
}
} else
prompt_tag = scheme_default_prompt_tag;
@ -6875,6 +6982,18 @@ Scheme_Object *scheme_call_with_composable_no_dws (Scheme_Object *proc, Scheme_O
return do_call_with_control(2, a, 1);
}
static Scheme_Cont_Mark *copy_cm_shared_on_write(Scheme_Meta_Continuation *mc)
{
Scheme_Cont_Mark *cp;
cp = MALLOC_N(Scheme_Cont_Mark, mc->cont_mark_total);
memcpy(cp, mc->cont_mark_stack_copied, mc->cont_mark_total * sizeof(Scheme_Cont_Mark));
mc->cont_mark_stack_copied = cp;
mc->cm_shared = 0;
return cp;
}
static Scheme_Object *continuation_marks(Scheme_Thread *p,
Scheme_Object *_cont,
Scheme_Object *econt,
@ -7034,14 +7153,8 @@ static Scheme_Object *continuation_marks(Scheme_Thread *p,
pr->pos = find[pos].pos;
pr->next = NULL;
if (mc) {
if (mc->cm_shared) {
Scheme_Cont_Mark *cp;
cp = MALLOC_N(Scheme_Cont_Mark, mc->cont_mark_total);
memcpy(cp, mc->cont_mark_stack_copied, mc->cont_mark_total * sizeof(Scheme_Cont_Mark));
mc->cont_mark_stack_copied = cp;
find = cp;
mc->cm_shared = 0;
}
if (mc->cm_shared)
find = copy_cm_shared_on_write(mc);
mc->cm_caches = 1;
}
cache = find[pos].cache;
@ -7779,6 +7892,69 @@ scheme_extract_one_cc_mark_with_meta(Scheme_Object *mark_set, Scheme_Object *key
return NULL;
}
static Scheme_Object *get_set_cont_mark_by_pos(Scheme_Object *key,
Scheme_Thread *p,
Scheme_Meta_Continuation *mc,
MZ_MARK_POS_TYPE mpos,
Scheme_Object *val)
{
intptr_t findpos, bottom, startpos;
intptr_t pos;
int down_delta = 0;
Scheme_Cont_Mark *seg;
if (mc) {
startpos = mc->cont_mark_total;
bottom = 0;
} else {
startpos = (intptr_t)MZ_CONT_MARK_STACK;
if (!p->cont_mark_stack_segments)
findpos = 0;
bottom = p->cont_mark_stack_bottom;
}
findpos = startpos;
/* binary search: */
while (bottom < startpos) {
findpos = ((bottom + startpos) / 2) - down_delta;
if (mc) {
seg = mc->cont_mark_stack_copied;
pos = findpos;
} else {
seg = p->cont_mark_stack_segments[findpos >> SCHEME_LOG_MARK_SEGMENT_SIZE];
pos = findpos & SCHEME_MARK_SEGMENT_MASK;
}
if (seg[pos].pos == mpos) {
if (SAME_OBJ(seg[pos].key, key)) {
if (!val)
return seg[pos].val;
if (mc && mc->cm_shared)
seg = copy_cm_shared_on_write(mc);
seg[pos].val = val;
return scheme_void;
} else if (findpos > bottom) {
down_delta++;
} else {
bottom = (findpos + down_delta) + 1;
down_delta = 0;
}
} else if (seg[pos].pos < mpos) {
bottom = findpos + 1;
} else {
startpos = findpos;
}
}
scheme_signal_error("get_set_cont_mark_by_pos: key not found");
return NULL;
}
Scheme_Object *
scheme_extract_one_cc_mark(Scheme_Object *mark_set, Scheme_Object *key)
{

2
src/racket/src/schpriv.h
View File

@ -1647,7 +1647,7 @@ typedef struct Scheme_Meta_Continuation {
typedef struct Scheme_Prompt {
Scheme_Object so;
char is_barrier, needs_cc_guard;
char is_barrier, has_chaperone;
Scheme_Object *tag;
Scheme_Object *id; /* created as needed; allows direct-jump optimization for cont app */
void *stack_boundary; /* where to stop copying the C stack */