x*/ REBRXT Do_Callback(REBSER *obj, u32 name, RXIARG *rxis, RXIARG *result) /* ** Given an object and a word id, call a REBOL function. ** The arguments are converted from extension format directly ** to the data stack. The result is passed back in ext format, ** with the datatype returned or zero if there was a problem. ** ***********************************************************************/ { REBVAL *val; struct Reb_Call *call; REBCNT len; REBCNT n; REBVAL label; REBVAL out; // Find word in object, verify it is a function. if (!(val = Find_Word_Value(obj, name))) { SET_EXT_ERROR(result, RXE_NO_WORD); return 0; } if (!ANY_FUNC(val)) { SET_EXT_ERROR(result, RXE_NOT_FUNC); return 0; } // Create stack frame (use prior stack frame for location info): SET_TRASH_SAFE(&out); // OUT slot for function eval result Val_Init_Word_Unbound(&label, REB_WORD, name); call = Make_Call( &out, VAL_SERIES(DSF_WHERE(PRIOR_DSF(DSF))), VAL_INDEX(DSF_WHERE(PRIOR_DSF(DSF))), &label, val ); obj = VAL_FUNC_PARAMLIST(val); // func words len = SERIES_TAIL(obj)-1; // number of args (may include locals) // Push args. Too short or too long arg frames are handled W/O error. // Note that refinements args can be set to anything. for (n = 1; n <= len; n++) { REBVAL *arg = DSF_ARG(call, n); if (n <= RXI_COUNT(rxis)) RXI_To_Value(arg, rxis[n], RXI_TYPE(rxis, n)); else SET_NONE(arg); // Check type for word at the given offset: if (!TYPE_CHECK(BLK_SKIP(obj, n), VAL_TYPE(arg))) { result->i2.int32b = n; SET_EXT_ERROR(result, RXE_BAD_ARGS); Free_Call(call); return 0; } } // Evaluate the function: if (Dispatch_Call_Throws(call)) { // !!! Does this need handling such that there is a way for the thrown // value to "bubble up" out of the callback, or is an error sufficient? fail (Error_No_Catch_For_Throw(DSF_OUT(call))); } // Return resulting value from output *result = Value_To_RXI(&out); return Reb_To_RXT[VAL_TYPE(&out)]; }
// // 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; }