//
// Dump_Stack: C
//
// Prints stack counting levels from the passed in number. Pass 0 to start.
//
void Dump_Stack(REBFRM *f, REBCNT level)
{
REBINT n;
REBVAL *arg;
REBVAL *param;
Debug_Fmt(""); // newline.
if (f == NULL) f = FS_TOP;
if (f == NULL) {
Debug_Fmt("*STACK[] - NO FRAMES*");
return;
}
Debug_Fmt(
"STACK[%d](%s) - %d",
level,
STR_HEAD(FRM_LABEL(f)),
f->eval_type // note: this is now an ordinary Reb_Kind, stringify it
);
if (NOT(Is_Any_Function_Frame(f))) {
Debug_Fmt("(no function call pending or in progress)");
return;
}
n = 1;
arg = FRM_ARG(f, 1);
param = FUNC_PARAMS_HEAD(f->func);
for (; NOT_END(param); ++param, ++arg, ++n) {
Debug_Fmt(
" %s: %72r",
STR_HEAD(VAL_PARAM_SPELLING(param)),
arg
);
}
if (f->prior)
Dump_Stack(f->prior, level + 1);
}
//
// Make_Where_For_Frame: C
//
// Each call frame maintains the array it is executing in, the current index
// in that array, and the index of where the current expression started.
// This can be deduced into a segment of code to display in the debug views
// to indicate roughly "what's running" at that stack level.
//
// Unfortunately, Rebol doesn't formalize this very well. There is no lock
// on segments of blocks during their evaluation, and it's possible for
// self-modifying code to scramble the blocks being executed. The DO
// evaluator is robust in terms of not *crashing*, but the semantics may well
// suprise users.
//
// !!! Should blocks on the stack be locked from modification, at least by
// default unless a special setting for self-modifying code unlocks it?
//
// So long as WHERE information is unreliable, this has to check that
// `expr_index` (where the evaluation started) and `index` (where the
// evaluation thinks it currently is) aren't out of bounds here. We could
// be giving back positions now unrelated to the call...but it won't crash!
//
REBARR *Make_Where_For_Frame(struct Reb_Frame *frame)
{
REBCNT start;
REBCNT end;
REBARR *where;
REBOOL pending;
if (FRM_IS_VALIST(frame)) {
const REBOOL truncated = TRUE;
Reify_Va_To_Array_In_Frame(frame, truncated);
}
// WARNING: MIN is a C macro and repeats its arguments.
//
start = MIN(ARR_LEN(FRM_ARRAY(frame)), cast(REBCNT, frame->expr_index));
end = MIN(ARR_LEN(FRM_ARRAY(frame)), FRM_INDEX(frame));
assert(end >= start);
assert(frame->mode != CALL_MODE_GUARD_ARRAY_ONLY);
pending = NOT(frame->mode == CALL_MODE_FUNCTION);
// Do a shallow copy so that the WHERE information only includes
// the range of the array being executed up to the point of
// currently relevant evaluation, not all the way to the tail
// of the block (where future potential evaluation would be)
{
REBCNT n = 0;
REBCNT len =
1 // fake function word (compensates for prefetch)
+ (end - start) // data from expr_index to the current index
+ (pending ? 1 : 0); // if it's pending we put "..." to show that
where = Make_Array(len);
// !!! Due to "prefetch" the expr_index will be *past* the invocation
// of the function. So this is a lie, as a placeholder for what a
// real debug mode would need to actually save the data to show.
// If the execution were a path or anything other than a word, this
// will lose it.
//
Val_Init_Word(ARR_AT(where, n), REB_WORD, FRM_LABEL(frame));
++n;
for (n = 1; n < len; ++n)
*ARR_AT(where, n) = *ARR_AT(FRM_ARRAY(frame), start + n - 1);
SET_ARRAY_LEN(where, len);
TERM_ARRAY(where);
}
// Making a shallow copy offers another advantage, that it's
// possible to get rid of the newline marker on the first element,
// that would visually disrupt the backtrace for no reason.
//
if (end - start > 0)
CLEAR_VAL_FLAG(ARR_HEAD(where), VALUE_FLAG_LINE);
// We add an ellipsis to a pending frame to make it a little bit
// clearer what is going on. If someone sees a where that looks
// like just `* [print]` the asterisk alone doesn't quite send
// home the message that print is not running and it is
// argument fulfillment that is why it's not "on the stack"
// yet, so `* [print ...]` is an attempt to say that better.
//
// !!! This is in-band, which can be mixed up with literal usage
// of ellipsis. Could there be a better "out-of-band" conveyance?
// Might the system use colorization in a value option bit.
//
if (pending)
Val_Init_Word(Alloc_Tail_Array(where), REB_WORD, SYM_ELLIPSIS);
return where;
}
