//
// Do_Path_Throws: 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(
REBVAL *out,
REBSYM *label_sym,
const REBVAL *path,
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(out));
assert(!IN_DATA_STACK(path));
assert(!opt_setval || !IN_DATA_STACK(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!
// 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);
if (IS_UNSET(pvs.value))
fail (Error(RE_NO_VALUE, pvs.item));
}
else {
// !!! Ideally there would be some way to protect pvs.value during
// successive path dispatches to make sure it does not get written.
// This is semi-dangerously giving pvs.value a reference into the
// input path, which should not be modified!
pvs.value = VAL_ARRAY_AT(pvs.orig);
}
// 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_0(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:
fail (Error(RE_INVALID_PATH, pvs.orig, pvs.item));
}
}
else if (!IS_FUNCTION(pvs.value))
fail (Error(RE_BAD_PATH_TYPE, pvs.orig, 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) *pvs.store = *pvs.value;
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_sym) {
REBVAL refinement;
VAL_INIT_WRITABLE_DEBUG(&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_sym = VAL_WORD_SYM(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_sym = 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_NONE(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_VAL_ARRAY_AT_THROWS(&refinement, pvs.item)) {
*out = refinement;
DS_DROP_TO(dsp_orig);
return TRUE;
}
if (IS_NONE(&refinement)) continue;
DS_PUSH(&refinement);
}
else if (IS_GET_WORD(pvs.item)) {
DS_PUSH_TRASH;
*DS_TOP = *GET_OPT_VAR_MAY_FAIL(pvs.item);
if (IS_NONE(DS_TOP)) {
DS_DROP;
continue;
}
}
else DS_PUSH(pvs.item);
// 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_SYM(DS_TOP, SYMBOL_TO_CANON(VAL_WORD_SYM(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;
}
*/ static REBCNT Parse_Rules_Loop(REBPARSE *parse, REBCNT index, REBVAL *rules, REBCNT depth)
/*
***********************************************************************/
{
REBSER *series = parse->series;
REBVAL *item; // current rule item
REBVAL *word; // active word to be set
REBCNT start; // recovery restart point
REBCNT i; // temp index point
REBCNT begin; // point at beginning of match
REBINT count; // iterated pattern counter
REBINT mincount; // min pattern count
REBINT maxcount; // max pattern count
REBVAL *item_hold;
REBVAL *val; // spare
REBCNT rulen;
REBSER *ser;
REBFLG flags;
REBCNT cmd;
REBVAL *rule_head = rules;
CHECK_STACK(&flags);
//if (depth > MAX_PARSE_DEPTH) Trap_Word(RE_LIMIT_HIT, SYM_PARSE, 0);
flags = 0;
word = 0;
mincount = maxcount = 1;
start = begin = index;
// For each rule in the rule block:
while (NOT_END(rules)) {
//Print_Parse_Index(parse->type, rules, series, index);
if (--Eval_Count <= 0 || Eval_Signals) Do_Signals();
//--------------------------------------------------------------------
// Pre-Rule Processing Section
//
// For non-iterated rules, including setup for iterated rules.
// The input index is not advanced here, but may be changed by
// a GET-WORD variable.
//--------------------------------------------------------------------
item = rules++;
// If word, set-word, or get-word, process it:
if (VAL_TYPE(item) >= REB_WORD && VAL_TYPE(item) <= REB_GET_WORD) {
// Is it a command word?
if (cmd = VAL_CMD(item)) {
if (!IS_WORD(item)) Trap1(RE_PARSE_COMMAND, item); // SET or GET not allowed
if (cmd <= SYM_BREAK) { // optimization
switch (cmd) {
case SYM_OR_BAR:
return index; // reached it successfully
// Note: mincount = maxcount = 1 on entry
case SYM_WHILE:
SET_FLAG(flags, PF_WHILE);
case SYM_ANY:
mincount = 0;
case SYM_SOME:
maxcount = MAX_I32;
continue;
case SYM_OPT:
mincount = 0;
continue;
case SYM_COPY:
SET_FLAG(flags, PF_COPY);
case SYM_SET:
SET_FLAG(flags, PF_SET);
item = rules++;
if (!IS_WORD(item)) Trap1(RE_PARSE_VARIABLE, item);
if (VAL_CMD(item)) Trap1(RE_PARSE_COMMAND, item);
word = item;
continue;
case SYM_NOT:
SET_FLAG(flags, PF_NOT);
flags ^= (1<<PF_NOT2);
continue;
case SYM_AND:
SET_FLAG(flags, PF_AND);
continue;
case SYM_THEN:
SET_FLAG(flags, PF_THEN);
continue;
case SYM_REMOVE:
SET_FLAG(flags, PF_REMOVE);
continue;
case SYM_INSERT:
SET_FLAG(flags, PF_INSERT);
goto post;
case SYM_CHANGE:
SET_FLAG(flags, PF_CHANGE);
continue;
case SYM_RETURN:
if (IS_PAREN(rules)) {
item = Do_Block_Value_Throw(rules); // might GC
Throw_Return_Value(item);
}
SET_FLAG(flags, PF_RETURN);
continue;
case SYM_ACCEPT:
case SYM_BREAK:
parse->result = 1;
return index;
case SYM_REJECT:
parse->result = -1;
return index;
case SYM_FAIL:
index = NOT_FOUND;
goto post;
case SYM_IF:
item = rules++;
if (IS_END(item)) goto bad_end;
if (!IS_PAREN(item)) Trap1(RE_PARSE_RULE, item);
item = Do_Block_Value_Throw(item); // might GC
if (IS_TRUE(item)) continue;
else {
index = NOT_FOUND;
goto post;
}
case SYM_LIMIT:
Trap0(RE_NOT_DONE);
//val = Get_Parse_Value(rules++);
// if (IS_INTEGER(val)) limit = index + Int32(val);
// else if (ANY_SERIES(val)) limit = VAL_INDEX(val);
// else goto
//goto bad_rule;
// goto post;
case SYM_QQ:
Print_Parse_Index(parse->type, rules, series, index);
continue;
}
}
// Any other cmd must be a match command, so proceed...
} else { // It's not a PARSE command, get or set it:
// word: - set a variable to the series at current index
if (IS_SET_WORD(item)) {
Set_Var_Series(item, parse->type, series, index);
continue;
}
// :word - change the index for the series to a new position
if (IS_GET_WORD(item)) {
item = Get_Var(item);
// CureCode #1263 change
//if (parse->type != VAL_TYPE(item) || VAL_SERIES(item) != series)
// Trap1(RE_PARSE_SERIES, rules-1);
if (!ANY_SERIES(item)) Trap1(RE_PARSE_SERIES, rules-1);
index = Set_Parse_Series(parse, item);
series = parse->series;
continue;
}
// word - some other variable
if (IS_WORD(item)) {
item = Get_Var(item);
}
// item can still be 'word or /word
}
}
else if (ANY_PATH(item)) {
item = Do_Parse_Path(item, parse, &index); // index can be modified
if (index > series->tail) index = series->tail;
if (item == 0) continue; // for SET and GET cases
}
if (IS_PAREN(item)) {
Do_Block_Value_Throw(item); // might GC
if (index > series->tail) index = series->tail;
continue;
}
// Counter? 123
if (IS_INTEGER(item)) { // Specify count or range count
SET_FLAG(flags, PF_WHILE);
mincount = maxcount = Int32s(item, 0);
item = Get_Parse_Value(rules++);
if (IS_END(item)) Trap1(RE_PARSE_END, rules-2);
if (IS_INTEGER(item)) {
maxcount = Int32s(item, 0);
item = Get_Parse_Value(rules++);
if (IS_END(item)) Trap1(RE_PARSE_END, rules-2);
}
}
// else fall through on other values and words
//--------------------------------------------------------------------
// Iterated Rule Matching Section:
//
// Repeats the same rule N times or until the rule fails.
// The index is advanced and stored in a temp variable i until
// the entire rule has been satisfied.
//--------------------------------------------------------------------
item_hold = item; // a command or literal match value
if (VAL_TYPE(item) <= REB_UNSET || VAL_TYPE(item) >= REB_NATIVE) goto bad_rule;
begin = index; // input at beginning of match section
rulen = 0; // rules consumed (do not use rule++ below)
i = index;
//note: rules var already advanced
for (count = 0; count < maxcount;) {
item = item_hold;
if (IS_WORD(item)) {
switch (cmd = VAL_WORD_CANON(item)) {
case SYM_SKIP:
i = (index < series->tail) ? index+1 : NOT_FOUND;
break;
case SYM_END:
i = (index < series->tail) ? NOT_FOUND : series->tail;
break;
case SYM_TO:
case SYM_THRU:
if (IS_END(rules)) goto bad_end;
item = Get_Parse_Value(rules);
rulen = 1;
i = Parse_To(parse, index, item, cmd == SYM_THRU);
break;
case SYM_QUOTE:
if (IS_END(rules)) goto bad_end;
rulen = 1;
if (IS_PAREN(rules)) {
item = Do_Block_Value_Throw(rules); // might GC
}
else item = rules;
i = (0 == Cmp_Value(BLK_SKIP(series, index), item, parse->flags & AM_FIND_CASE)) ? index+1 : NOT_FOUND;
break;
case SYM_INTO:
if (IS_END(rules)) goto bad_end;
rulen = 1;
item = Get_Parse_Value(rules); // sub-rules
if (!IS_BLOCK(item)) goto bad_rule;
val = BLK_SKIP(series, index);
i = (
(ANY_BINSTR(val) || ANY_BLOCK(val))
&& (Parse_Series(val, VAL_BLK_DATA(item), parse->flags, depth+1) == VAL_TAIL(val))
) ? index+1 : NOT_FOUND;
break;
case SYM_DO:
if (!IS_BLOCK_INPUT(parse)) goto bad_rule;
i = Do_Eval_Rule(parse, index, &rules);
rulen = 1;
break;
default:
goto bad_rule;
}
}
else if (IS_BLOCK(item)) {
item = VAL_BLK_DATA(item);
//if (IS_END(rules) && item == rule_head) {
// rules = item;
// goto top;
//}
i = Parse_Rules_Loop(parse, index, item, depth+1);
if (parse->result) {
index = (parse->result > 0) ? i : NOT_FOUND;
parse->result = 0;
break;
}
}
// Parse according to datatype:
else {
if (IS_BLOCK_INPUT(parse))
i = Parse_Next_Block(parse, index, item, depth+1);
else
i = Parse_Next_String(parse, index, item, depth+1);
}
// Necessary for special cases like: some [to end]
// i: indicates new index or failure of the match, but
// that does not mean failure of the rule, because optional
// matches can still succeed, if if the last match failed.
if (i != NOT_FOUND) {
count++; // may overflow to negative
if (count < 0) count = MAX_I32; // the forever case
// If input did not advance:
if (i == index && !GET_FLAG(flags, PF_WHILE)) {
if (count < mincount) index = NOT_FOUND; // was not enough
break;
}
}
//if (i >= series->tail) { // OLD check: no more input
else {
if (count < mincount) index = NOT_FOUND; // was not enough
else if (i != NOT_FOUND) index = i;
// else keep index as is.
break;
}
index = i;
// A BREAK word stopped us:
//if (parse->result) {parse->result = 0; break;}
}
rules += rulen;
//if (index > series->tail && index != NOT_FOUND) index = series->tail;
if (index > series->tail) index = NOT_FOUND;
//--------------------------------------------------------------------
// Post Match Processing:
//--------------------------------------------------------------------
post:
// Process special flags:
if (flags) {
// NOT before all others:
if (GET_FLAG(flags, PF_NOT)) {
if (GET_FLAG(flags, PF_NOT2) && index != NOT_FOUND) index = NOT_FOUND;
else index = begin;
}
if (index == NOT_FOUND) { // Failure actions:
// not decided: if (word) Set_Var_Basic(word, REB_NONE);
if (GET_FLAG(flags, PF_THEN)) {
SKIP_TO_BAR(rules);
if (!IS_END(rules)) rules++;
}
}
else { // Success actions:
count = (begin > index) ? 0 : index - begin; // how much we advanced the input
if (GET_FLAG(flags, PF_COPY)) {
ser = (IS_BLOCK_INPUT(parse))
? Copy_Block_Len(series, begin, count)
: Copy_String(series, begin, count); // condenses
Set_Var_Series(word, parse->type, ser, 0);
}
else if (GET_FLAG(flags, PF_SET)) {
if (IS_BLOCK_INPUT(parse)) {
item = Get_Var_Safe(word);
if (count == 0) SET_NONE(item);
else *item = *BLK_SKIP(series, begin);
}
else {
item = Get_Var_Safe(word);
if (count == 0) SET_NONE(item);
else {
i = GET_ANY_CHAR(series, begin);
if (parse->type == REB_BINARY) {
SET_INTEGER(item, i);
} else {
SET_CHAR(item, i);
}
}
}
}
if (GET_FLAG(flags, PF_RETURN)) {
ser = (IS_BLOCK_INPUT(parse))
? Copy_Block_Len(series, begin, count)
: Copy_String(series, begin, count); // condenses
Throw_Return_Series(parse->type, ser);
}
if (GET_FLAG(flags, PF_REMOVE)) {
if (count) Remove_Series(series, begin, count);
index = begin;
}
if (flags & (1<<PF_INSERT | 1<<PF_CHANGE)) {
count = GET_FLAG(flags, PF_INSERT) ? 0 : count;
cmd = GET_FLAG(flags, PF_INSERT) ? 0 : (1<<AN_PART);
item = rules++;
if (IS_END(item)) goto bad_end;
// Check for ONLY flag:
if (IS_WORD(item) && NZ(cmd = VAL_CMD(item))) {
if (cmd != SYM_ONLY) goto bad_rule;
cmd |= (1<<AN_ONLY);
item = rules++;
}
// CHECK FOR QUOTE!!
item = Get_Parse_Value(item); // new value
if (IS_UNSET(item)) Trap1(RE_NO_VALUE, rules-1);
if (IS_END(item)) goto bad_end;
if (IS_BLOCK_INPUT(parse)) {
index = Modify_Block(GET_FLAG(flags, PF_CHANGE) ? A_CHANGE : A_INSERT,
series, begin, item, cmd, count, 1);
if (IS_LIT_WORD(item)) SET_TYPE(BLK_SKIP(series, index-1), REB_WORD);
}
else {
if (parse->type == REB_BINARY) cmd |= (1<<AN_SERIES); // special flag
index = Modify_String(GET_FLAG(flags, PF_CHANGE) ? A_CHANGE : A_INSERT,
series, begin, item, cmd, count, 1);
}
}
if (GET_FLAG(flags, PF_AND)) index = begin;
}
flags = 0;
word = 0;
}
// Goto alternate rule and reset input:
if (index == NOT_FOUND) {
SKIP_TO_BAR(rules);
if (IS_END(rules)) break;
rules++;
index = begin = start;
}
begin = index;
mincount = maxcount = 1;
}
return index;
bad_rule:
Trap1(RE_PARSE_RULE, rules-1);
bad_end:
Trap1(RE_PARSE_END, rules-1);
return 0;
}
