code.cpp

Local<Object> TermQuery(Local<Value> termString) {
    Local<Object> variables = Nan::New<Object>();
    String::Utf8Value string(termString);
    term_t t = PL_new_term_ref();
    if (!PL_chars_to_term(*string, t)) {
        Nan::ThrowError("PL_chars_to_term failed.");
        return variables;
    }
    functor_t f;
    if (!PL_get_functor(t, &f)) {
        Nan::ThrowError("PL_get_functor failed.");
        return variables;
    }
    int arity = PL_functor_arity(f);
    term_t args = PL_new_term_refs(arity);
    for (int i = 1; i <= arity; ++i) {
        if (!PL_get_arg(i, t, args + i - 1)) {
            Nan::ThrowError("PL_get_arg failed.");
            return variables;
        }
        int type = PL_term_type(args + i - 1);
        char *msg;
        if (type == PL_VARIABLE) {
            if (!PL_get_chars(args + i - 1, &msg, CVT_VARIABLE)) {
                Nan::ThrowError("PL_get_chars failed.");
                return variables;
            }
        }
        variables->Set(Nan::New<String>(msg).ToLocalChecked(), Nan::Null());
    }
    predicate_t p = PL_pred(f, NULL);
    int flags = PL_Q_NODEBUG | PL_Q_CATCH_EXCEPTION;
    qid_t q = PL_open_query(NULL, flags, p, args);
    if (!PL_next_solution(q)) {
        Nan::ThrowError("PL_next_solution failed.");
        return variables;
    }
    return variables;
}