//
// COPY_VALUE_Debug: C
//
// The implementation of COPY_VALUE_CORE is designed to be fairly optimal
// (since it is being called in lieu of what would have been a memcpy() or
// plain assignment). It is left in its raw form as an inline function to
// to help convey that it is nearly as efficient as an assignment.
//
// This adds some verbose checking in the debug build to help debug cases
// where the relative information bits are incorrect.
//
void COPY_VALUE_Debug(
REBVAL *dest,
const RELVAL *src,
REBCTX *specifier
) {
assert(!IS_END(src));
assert(!IS_TRASH_DEBUG(src));
#ifdef __cplusplus
Assert_Cell_Writable(dest, __FILE__, __LINE__);
#endif
if (IS_RELATIVE(src)) {
assert(ANY_WORD(src) || ANY_ARRAY(src));
if (specifier == SPECIFIED) {
Debug_Fmt("Internal Error: Relative item used with SPECIFIED");
PROBE_MSG(src, "word or array");
PROBE_MSG(FUNC_VALUE(VAL_RELATIVE(src)), "func");
assert(FALSE);
}
else if (
VAL_RELATIVE(src)
!= VAL_FUNC(CTX_FRAME_FUNC_VALUE(specifier))
) {
Debug_Fmt("Internal Error: Function mismatch in specific binding");
PROBE_MSG(src, "word or array");
PROBE_MSG(FUNC_VALUE(VAL_RELATIVE(src)), "expected func");
PROBE_MSG(CTX_FRAME_FUNC_VALUE(specifier), "actual func");
assert(FALSE);
}
}
COPY_VALUE_CORE(dest, src, specifier);
}
//
// Copy_Rerelativized_Array_Deep_Managed: C
//
// The invariant of copying in general is that when you are done with the
// copy, there are no relative values in that copy. One exception to this
// is the deep copy required to make a relative function body in the first
// place (which it currently does in two passes--a normal deep copy followed
// by a relative binding). The other exception is when a relativized
// function body is copied to make another relativized function body.
//
// This is specialized logic for the latter case. It's constrained enough
// to be simple (all relative values are known to be relative to the same
// function), and the feature is questionable anyway. So it's best not to
// further complicate ordinary copying with a parameterization to copy
// and change all the relative binding information from one function's
// paramlist to another.
//
REBARR *Copy_Rerelativized_Array_Deep_Managed(
REBARR *original,
REBACT *before, // references to `before` will be changed to `after`
REBACT *after
){
const REBFLGS flags = NODE_FLAG_MANAGED;
REBARR *copy = Make_Array_For_Copy(ARR_LEN(original), flags, original);
RELVAL *src = ARR_HEAD(original);
RELVAL *dest = ARR_HEAD(copy);
for (; NOT_END(src); ++src, ++dest) {
if (not IS_RELATIVE(src)) {
Move_Value(dest, KNOWN(src));
continue;
}
// All relative values under a sub-block must be relative to the
// same function.
//
assert(VAL_RELATIVE(src) == before);
Move_Value_Header(dest, src);
if (ANY_ARRAY_OR_PATH(src)) {
INIT_VAL_NODE(
dest,
Copy_Rerelativized_Array_Deep_Managed(
VAL_ARRAY(src), before, after
)
);
PAYLOAD(Any, dest).second = PAYLOAD(Any, src).second;
INIT_BINDING(dest, after); // relative binding
}
else {
assert(ANY_WORD(src));
PAYLOAD(Any, dest) = PAYLOAD(Any, src);
INIT_BINDING(dest, after);
}
}
TERM_ARRAY_LEN(copy, ARR_LEN(original));
return copy;
}
//
// Do_Path_Throws_Core: C
//
// Evaluate an ANY_PATH! REBVAL, starting from the index position of that
// path value and continuing to the end.
//
// The evaluator may throw because GROUP! is evaluated, e.g. `foo/(throw 1020)`
//
// If label_sym is passed in as being non-null, then the caller is implying
// readiness to process a path which may be a function with refinements.
// These refinements will be left in order on the data stack in the case
// that `out` comes back as IS_FUNCTION().
//
// If `opt_setval` is given, the path operation will be done as a "SET-PATH!"
// if the path evaluation did not throw or error. HOWEVER the set value
// is NOT put into `out`. This provides more flexibility on performance in
// the evaluator, which may already have the `val` where it wants it, and
// so the extra assignment would just be overhead.
//
// !!! Path evaluation is one of the parts of R3-Alpha that has not been
// vetted very heavily by Ren-C, and needs a review and overhaul.
//
REBOOL Do_Path_Throws_Core(
REBVAL *out,
REBSTR **label_out,
const RELVAL *path,
REBCTX *specifier,
REBVAL *opt_setval
) {
REBPVS pvs;
REBDSP dsp_orig = DSP;
assert(ANY_PATH(path));
// !!! There is a bug in the dispatch such that if you are running a
// set path, it does not always assign the output, because it "thinks you
// aren't going to look at it". This presumably originated from before
// parens were allowed in paths, and neglects cases like:
//
// foo/(throw 1020): value
//
// We always have to check to see if a throw occurred. Until this is
// streamlined, we have to at minimum set it to something that is *not*
// thrown so that we aren't testing uninitialized memory. A safe trash
// will do, which is unset in release builds.
//
if (opt_setval)
SET_TRASH_SAFE(out);
// None of the values passed in can live on the data stack, because
// they might be relocated during the path evaluation process.
//
assert(!IN_DATA_STACK_DEBUG(out));
assert(!IN_DATA_STACK_DEBUG(path));
assert(!opt_setval || !IN_DATA_STACK_DEBUG(opt_setval));
// Not currently robust for reusing passed in path or value as the output
assert(out != path && out != opt_setval);
assert(!opt_setval || !THROWN(opt_setval));
// Initialize REBPVS -- see notes in %sys-do.h
//
pvs.opt_setval = opt_setval;
pvs.store = out;
pvs.orig = path;
pvs.item = VAL_ARRAY_AT(pvs.orig); // may not be starting at head of PATH!
// The path value that's coming in may be relative (in which case it
// needs to use the specifier passed in). Or it may be specific already,
// in which case we should use the specifier in the value to process
// its array contents.
//
if (IS_RELATIVE(path)) {
#if !defined(NDEBUG)
assert(specifier != SPECIFIED);
if (VAL_RELATIVE(path) != VAL_FUNC(CTX_FRAME_FUNC_VALUE(specifier))) {
Debug_Fmt("Specificity mismatch found in path dispatch");
PROBE_MSG(path, "the path being evaluated");
PROBE_MSG(FUNC_VALUE(VAL_RELATIVE(path)), "expected func");
PROBE_MSG(CTX_FRAME_FUNC_VALUE(specifier), "actual func");
assert(FALSE);
}
#endif
pvs.item_specifier = specifier;
}
else pvs.item_specifier = VAL_SPECIFIER(const_KNOWN(path));
// Seed the path evaluation process by looking up the first item (to
// get a datatype to dispatch on for the later path items)
//
if (IS_WORD(pvs.item)) {
pvs.value = GET_MUTABLE_VAR_MAY_FAIL(pvs.item, pvs.item_specifier);
pvs.value_specifier = SPECIFIED;
if (IS_VOID(pvs.value))
fail (Error_No_Value_Core(pvs.item, pvs.item_specifier));
}
else {
// !!! Ideally there would be some way to deal with writes to
// temporary locations, like this pvs.value...if a set-path sets
// it, then it will be discarded.
COPY_VALUE(pvs.store, VAL_ARRAY_AT(pvs.orig), pvs.item_specifier);
pvs.value = pvs.store;
pvs.value_specifier = SPECIFIED;
}
// Start evaluation of path:
if (IS_END(pvs.item + 1)) {
// If it was a single element path, return the value rather than
// try to dispatch it (would cause a crash at time of writing)
//
// !!! Is this the desired behavior, or should it be an error?
}
else if (Path_Dispatch[VAL_TYPE(pvs.value)]) {
REBOOL threw = Next_Path_Throws(&pvs);
// !!! See comments about why the initialization of out is necessary.
// Without it this assertion can change on some things:
//
// t: now
// t/time: 10:20:03
//
// (It thinks pvs.value has its THROWN bit set when it completed
// successfully. It was a PE_USE_STORE case where pvs.value was reset to
// pvs.store, and pvs.store has its thrown bit set. Valgrind does not
// catch any uninitialized variables.)
//
// There are other cases that do trip valgrind when omitting the
// initialization, though not as clearly reproducible.
//
assert(threw == THROWN(pvs.value));
if (threw) return TRUE;
// Check for errors:
if (NOT_END(pvs.item + 1) && !IS_FUNCTION(pvs.value)) {
//
// Only function refinements should get by this line:
REBVAL specified_orig;
COPY_VALUE(&specified_orig, pvs.orig, specifier);
REBVAL specified_item;
COPY_VALUE(&specified_item, pvs.item, specifier);
fail (Error(RE_INVALID_PATH, &specified_orig, &specified_item));
}
}
else if (!IS_FUNCTION(pvs.value)) {
REBVAL specified;
COPY_VALUE(&specified, pvs.orig, specifier);
fail (Error(RE_BAD_PATH_TYPE, &specified, Type_Of(pvs.value)));
}
if (opt_setval) {
// If SET then we don't return anything
assert(IS_END(pvs.item) + 1);
return FALSE;
}
// If storage was not used, then copy final value back to it:
if (pvs.value != pvs.store)
COPY_VALUE(pvs.store, pvs.value, pvs.value_specifier);
assert(!THROWN(out));
// Return 0 if not function or is :path/word...
if (!IS_FUNCTION(pvs.value)) {
assert(IS_END(pvs.item) + 1);
return FALSE;
}
if (label_out) {
REBVAL refinement;
// When a function is hit, path processing stops as soon as the
// processed sub-path resolves to a function. The path is still sitting
// on the position of the last component of that sub-path. Usually,
// this last component in the sub-path is a word naming the function.
//
if (IS_WORD(pvs.item)) {
*label_out = VAL_WORD_SPELLING(pvs.item);
}
else {
// In rarer cases, the final component (completing the sub-path to
// the function to call) is not a word. Such as when you use a path
// to pick by index out of a block of functions:
//
// functions: reduce [:add :subtract]
// functions/1 10 20
//
// Or when you have an immediate function value in a path with a
// refinement. Tricky to make, but possible:
//
// do reduce [
// to-path reduce [:append 'only] [a] [b]
// ]
//
// !!! When a function was not invoked through looking up a word
// (or a word in a path) to use as a label, there were once three
// different alternate labels used. One was SYM__APPLY_, another
// was ROOT_NONAME, and another was to be the type of the function
// being executed. None are fantastic, we do the type for now.
*label_out = Canon(SYM_FROM_KIND(VAL_TYPE(pvs.value)));
}
// Move on to the refinements (if any)
++pvs.item;
// !!! Currently, the mainline path evaluation "punts" on refinements.
// When it finds a function, it stops the path evaluation and leaves
// the position pvs.path before the list of refinements.
//
// A more elegant solution would be able to process and notice (for
// instance) that `:APPEND/ONLY` should yield a function value that
// has been specialized with a refinement. Path chaining should thus
// be able to effectively do this and give the refined function object
// back to the evaluator or other client.
//
// If a label_sym is passed in, we recognize that a function dispatch
// is going to be happening. We do not want to pay to generate the
// new series that would be needed to make a temporary function that
// will be invoked and immediately GC'd So we gather the refinements
// on the data stack.
//
// This code simulates that path-processing-to-data-stack, but it
// should really be something in dispatch iself. In any case, we put
// refinements on the data stack...and caller knows refinements are
// from dsp_orig to DSP (thanks to accounting, all other operations
// should balance!)
for (; NOT_END(pvs.item); ++pvs.item) { // "the refinements"
if (IS_VOID(pvs.item)) continue;
if (IS_GROUP(pvs.item)) {
//
// Note it is not legal to use the data stack directly as the
// output location for a DO (might be resized)
if (Do_At_Throws(
&refinement,
VAL_ARRAY(pvs.item),
VAL_INDEX(pvs.item),
IS_RELATIVE(pvs.item)
? pvs.item_specifier // if relative, use parent's
: VAL_SPECIFIER(const_KNOWN(pvs.item)) // else embedded
)) {
*out = refinement;
DS_DROP_TO(dsp_orig);
return TRUE;
}
if (IS_VOID(&refinement)) continue;
DS_PUSH(&refinement);
}
else if (IS_GET_WORD(pvs.item)) {
DS_PUSH_TRASH;
*DS_TOP = *GET_OPT_VAR_MAY_FAIL(pvs.item, pvs.item_specifier);
if (IS_VOID(DS_TOP)) {
DS_DROP;
continue;
}
}
else DS_PUSH_RELVAL(pvs.item, pvs.item_specifier);
// Whatever we were trying to use as a refinement should now be
// on the top of the data stack, and only words are legal ATM
//
if (!IS_WORD(DS_TOP)) {
fail (Error(RE_BAD_REFINE, DS_TOP));
}
// Go ahead and canonize the word symbol so we don't have to
// do it each time in order to get a case-insenstive compare
//
INIT_WORD_SPELLING(DS_TOP, VAL_WORD_CANON(DS_TOP));
}
// To make things easier for processing, reverse the refinements on
// the data stack (we needed to evaluate them in forward order).
// This way we can just pop them as we go, and know if they weren't
// all consumed if it doesn't get back to `dsp_orig` by the end.
if (dsp_orig != DSP) {
REBVAL *bottom = DS_AT(dsp_orig + 1);
REBVAL *top = DS_TOP;
while (top > bottom) {
refinement = *bottom;
*bottom = *top;
*top = refinement;
top--;
bottom++;
}
}
}
else {
// !!! Historically this just ignores a result indicating this is a
// function with refinements, e.g. ':append/only'. However that
// ignoring seems unwise. It should presumably create a modified
// function in that case which acts as if it has the refinement.
//
// If the caller did not pass in a label pointer we assume they are
// likely not ready to process any refinements.
//
if (NOT_END(pvs.item + 1))
fail (Error(RE_TOO_LONG)); // !!! Better error or add feature
}
return FALSE;
}
