Exemple #1
0
void mp_parse_node_show(mp_parse_node_t pn, int indent) {
    for (int i = 0; i < indent; i++) {
        printf(" ");
    }
    if (MP_PARSE_NODE_IS_NULL(pn)) {
        printf("NULL\n");
    } else if (MP_PARSE_NODE_IS_LEAF(pn)) {
        int arg = MP_PARSE_NODE_LEAF_ARG(pn);
        switch (MP_PARSE_NODE_LEAF_KIND(pn)) {
            case MP_PARSE_NODE_ID: printf("id(%s)\n", qstr_str(arg)); break;
            case MP_PARSE_NODE_SMALL_INT: printf("int(%d)\n", arg); break;
            case MP_PARSE_NODE_INTEGER: printf("int(%s)\n", qstr_str(arg)); break;
            case MP_PARSE_NODE_DECIMAL: printf("dec(%s)\n", qstr_str(arg)); break;
            case MP_PARSE_NODE_STRING: printf("str(%s)\n", qstr_str(arg)); break;
            case MP_PARSE_NODE_BYTES: printf("bytes(%s)\n", qstr_str(arg)); break;
            case MP_PARSE_NODE_TOKEN: printf("tok(%d)\n", arg); break;
            default: assert(0);
        }
    } else {
        mp_parse_node_struct_t *pns2 = (mp_parse_node_struct_t*)pn;
        int n = pns2->kind_num_nodes >> 8;
#ifdef USE_RULE_NAME
        printf("%s(%d) (n=%d)\n", rules[MP_PARSE_NODE_STRUCT_KIND(pns2)]->rule_name, MP_PARSE_NODE_STRUCT_KIND(pns2), n);
#else
        printf("rule(%u) (n=%d)\n", (uint)MP_PARSE_NODE_STRUCT_KIND(pns2), n);
#endif
        for (int i = 0; i < n; i++) {
            mp_parse_node_show(pns2->nodes[i], indent + 2);
        }
    }
}
Exemple #2
0
// return empty string in case of error, so we can attempt to parse the string
// without a special check if it was in fact a string
STATIC const char *get_arg_str(mp_parse_node_t pn) {
    if (MP_PARSE_NODE_IS_ID(pn)) {
        qstr qst = MP_PARSE_NODE_LEAF_ARG(pn);
        return qstr_str(qst);
    } else {
        return "";
    }
}
STATIC uint get_arg_rlo(qstr op, mp_parse_node_t *pn_args, int wanted_arg_num) {
    if (!MP_PARSE_NODE_IS_ID(pn_args[wanted_arg_num])) {
        printf("SyntaxError: '%s' expects a register in position %d\n", qstr_str(op), wanted_arg_num);
        return 0;
    }
    qstr reg_qstr = MP_PARSE_NODE_LEAF_ARG(pn_args[wanted_arg_num]);
    const char *reg_str = qstr_str(reg_qstr);
    if (!(strlen(reg_str) == 2 && reg_str[0] == 'r' && ('0' <= reg_str[1] && reg_str[1] <= '7'))) {
        printf("SyntaxError: '%s' expects a register in position %d\n", qstr_str(op), wanted_arg_num);
        return 0;
    }
    return reg_str[1] - '0';
}
Exemple #4
0
scope_t *scope_new(scope_kind_t kind, mp_parse_node_t pn, qstr source_file, uint unique_code_id, uint emit_options) {
    scope_t *scope = m_new(scope_t, 1);
    scope->kind = kind;
    scope->parent = NULL;
    scope->next = NULL;
    scope->pn = pn;
    scope->source_file = source_file;
    switch (kind) {
        case SCOPE_MODULE:
            scope->simple_name = MP_QSTR__lt_module_gt_;
            break;
        case SCOPE_FUNCTION:
        case SCOPE_CLASS:
            assert(MP_PARSE_NODE_IS_STRUCT(pn));
            scope->simple_name = MP_PARSE_NODE_LEAF_ARG(((mp_parse_node_struct_t*)pn)->nodes[0]);
            break;
        case SCOPE_LAMBDA:
            scope->simple_name = MP_QSTR__lt_lambda_gt_;
            break;
        case SCOPE_LIST_COMP:
            scope->simple_name = MP_QSTR__lt_listcomp_gt_;
            break;
        case SCOPE_DICT_COMP:
            scope->simple_name = MP_QSTR__lt_dictcomp_gt_;
            break;
        case SCOPE_SET_COMP:
            scope->simple_name = MP_QSTR__lt_setcomp_gt_;
            break;
        case SCOPE_GEN_EXPR:
            scope->simple_name = MP_QSTR__lt_genexpr_gt_;
            break;
        default:
            assert(0);
    }
    scope->id_info_alloc = 8;
    scope->id_info_len = 0;
    scope->id_info = m_new(id_info_t, scope->id_info_alloc);

    scope->flags = 0;
    scope->num_params = 0;
    /* not needed
    scope->num_default_params = 0;
    scope->num_dict_params = 0;
    */
    scope->num_locals = 0;
    scope->unique_code_id = unique_code_id;
    scope->emit_options = emit_options;

    return scope;
}
Exemple #5
0
void mp_parse_node_print(mp_parse_node_t pn, size_t indent) {
    if (MP_PARSE_NODE_IS_STRUCT(pn)) {
        printf("[% 4d] ", (int)((mp_parse_node_struct_t*)pn)->source_line);
    } else {
        printf("       ");
    }
    for (size_t i = 0; i < indent; i++) {
        printf(" ");
    }
    if (MP_PARSE_NODE_IS_NULL(pn)) {
        printf("NULL\n");
    } else if (MP_PARSE_NODE_IS_SMALL_INT(pn)) {
        mp_int_t arg = MP_PARSE_NODE_LEAF_SMALL_INT(pn);
        printf("int(" INT_FMT ")\n", arg);
    } else if (MP_PARSE_NODE_IS_LEAF(pn)) {
        uintptr_t arg = MP_PARSE_NODE_LEAF_ARG(pn);
        switch (MP_PARSE_NODE_LEAF_KIND(pn)) {
            case MP_PARSE_NODE_ID: printf("id(%s)\n", qstr_str(arg)); break;
            case MP_PARSE_NODE_STRING: printf("str(%s)\n", qstr_str(arg)); break;
            case MP_PARSE_NODE_BYTES: printf("bytes(%s)\n", qstr_str(arg)); break;
            case MP_PARSE_NODE_TOKEN: printf("tok(%u)\n", (uint)arg); break;
            default: assert(0);
        }
    } else {
        // node must be a mp_parse_node_struct_t
        mp_parse_node_struct_t *pns = (mp_parse_node_struct_t*)pn;
        if (MP_PARSE_NODE_STRUCT_KIND(pns) == RULE_string) {
            printf("literal str(%.*s)\n", (int)pns->nodes[1], (char*)pns->nodes[0]);
        } else if (MP_PARSE_NODE_STRUCT_KIND(pns) == RULE_bytes) {
            printf("literal bytes(%.*s)\n", (int)pns->nodes[1], (char*)pns->nodes[0]);
        } else if (MP_PARSE_NODE_STRUCT_KIND(pns) == RULE_const_object) {
            #if MICROPY_OBJ_REPR == MICROPY_OBJ_REPR_D
            printf("literal const(%016llx)\n", (uint64_t)pns->nodes[0] | ((uint64_t)pns->nodes[1] << 32));
            #else
            printf("literal const(%p)\n", (mp_obj_t)pns->nodes[0]);
            #endif
        } else {
            size_t n = MP_PARSE_NODE_STRUCT_NUM_NODES(pns);
#ifdef USE_RULE_NAME
            printf("%s(%u) (n=%u)\n", rules[MP_PARSE_NODE_STRUCT_KIND(pns)]->rule_name, (uint)MP_PARSE_NODE_STRUCT_KIND(pns), (uint)n);
#else
            printf("rule(%u) (n=%u)\n", (uint)MP_PARSE_NODE_STRUCT_KIND(pns), (uint)n);
#endif
            for (size_t i = 0; i < n; i++) {
                mp_parse_node_print(pns->nodes[i], indent + 2);
            }
        }
    }
}
Exemple #6
0
STATIC int get_arg_label(emit_inline_asm_t *emit, const char *op, mp_parse_node_t pn) {
    if (!MP_PARSE_NODE_IS_ID(pn)) {
        emit_inline_thumb_error_exc(emit, mp_obj_new_exception_msg_varg(&mp_type_SyntaxError, "'%s' expects a label", op));
        return 0;
    }
    qstr label_qstr = MP_PARSE_NODE_LEAF_ARG(pn);
    for (uint i = 0; i < emit->max_num_labels; i++) {
        if (emit->label_lookup[i] == label_qstr) {
            return i;
        }
    }
    // only need to have the labels on the last pass
    if (emit->pass == MP_PASS_EMIT) {
        emit_inline_thumb_error_exc(emit, mp_obj_new_exception_msg_varg(&mp_type_SyntaxError, "label '%q' not defined", label_qstr));
    }
    return 0;
}
STATIC int get_arg_label(emit_inline_asm_t *emit, const char *op, mp_parse_node_t pn) {
    if (!MP_PARSE_NODE_IS_ID(pn)) {
        emit_inline_thumb_error(emit, "'%s' expects a label\n", op);
        return 0;
    }
    qstr label_qstr = MP_PARSE_NODE_LEAF_ARG(pn);
    for (int i = 0; i < emit->max_num_labels; i++) {
        if (emit->label_lookup[i] == label_qstr) {
            return i;
        }
    }
    // only need to have the labels on the last pass
    if (emit->pass == PASS_3) {
        emit_inline_thumb_error(emit, "label '%s' not defined\n", qstr_str(label_qstr));
    }
    return 0;
}
STATIC int get_arg_label(emit_inline_asm_t *emit, qstr op, mp_parse_node_t *pn_args, int wanted_arg_num) {
    if (!MP_PARSE_NODE_IS_ID(pn_args[wanted_arg_num])) {
        printf("SyntaxError: '%s' expects a label in position %d\n", qstr_str(op), wanted_arg_num);
        return 0;
    }
    qstr label_qstr = MP_PARSE_NODE_LEAF_ARG(pn_args[wanted_arg_num]);
    for (int i = 0; i < emit->max_num_labels; i++) {
        if (emit->label_lookup[i] == label_qstr) {
            return i;
        }
    }
    // only need to have the labels on the last pass
    if (emit->pass == PASS_3) {
        printf("SyntaxError: label '%s' not defined\n", qstr_str(label_qstr));
    }
    return 0;
}
Exemple #9
0
STATIC mp_uint_t emit_inline_thumb_count_params(emit_inline_asm_t *emit, mp_uint_t n_params, mp_parse_node_t *pn_params) {
    if (n_params > 4) {
        emit_inline_thumb_error_msg(emit, "can only have up to 4 parameters to Thumb assembly");
        return 0;
    }
    for (mp_uint_t i = 0; i < n_params; i++) {
        if (!MP_PARSE_NODE_IS_ID(pn_params[i])) {
            emit_inline_thumb_error_msg(emit, "parameters must be registers in sequence r0 to r3");
            return 0;
        }
        const char *p = qstr_str(MP_PARSE_NODE_LEAF_ARG(pn_params[i]));
        if (!(strlen(p) == 2 && p[0] == 'r' && p[1] == '0' + i)) {
            emit_inline_thumb_error_msg(emit, "parameters must be registers in sequence r0 to r3");
            return 0;
        }
    }
    return n_params;
}
STATIC int emit_inline_thumb_count_params(emit_inline_asm_t *emit, int n_params, mp_parse_node_t *pn_params) {
    if (n_params > 4) {
        emit_inline_thumb_error(emit, "can only have up to 4 parameters to inline thumb assembly\n");
        return 0;
    }
    for (int i = 0; i < n_params; i++) {
        if (!MP_PARSE_NODE_IS_ID(pn_params[i])) {
            emit_inline_thumb_error(emit, "parameter to inline assembler must be an identifier\n");
            return 0;
        }
        const char *p = qstr_str(MP_PARSE_NODE_LEAF_ARG(pn_params[i]));
        if (!(strlen(p) == 2 && p[0] == 'r' && p[1] == '0' + i)) {
            emit_inline_thumb_error(emit, "parameter %d to inline assembler must be r%d\n", i + 1, i);
            return 0;
        }
    }
    return n_params;
}
STATIC uint get_arg_reg(emit_inline_asm_t *emit, const char *op, mp_parse_node_t pn, uint max_reg) {
    if (MP_PARSE_NODE_IS_ID(pn)) {
        qstr reg_qstr = MP_PARSE_NODE_LEAF_ARG(pn);
        const char *reg_str = qstr_str(reg_qstr);
        for (uint i = 0; i < sizeof(reg_name_table) / sizeof(reg_name_table[0]); i++) {
            const reg_name_t *r = &reg_name_table[i];
            if (reg_str[0] == r->name[0] && reg_str[1] == r->name[1] && reg_str[2] == r->name[2] && (reg_str[2] == '\0' || reg_str[3] == '\0')) {
                if (r->reg > max_reg) {
                    emit_inline_thumb_error(emit, "'%s' expects at most r%d\n", op, max_reg);
                    return 0;
                } else {
                    return r->reg;
                }
            }
        }
    }
    emit_inline_thumb_error(emit, "'%s' expects a register\n", op);
    return 0;
}
Exemple #12
0
void mp_parse_node_print(mp_parse_node_t pn, int indent) {
    if (MP_PARSE_NODE_IS_STRUCT(pn)) {
        printf("[% 4d] ", (int)((mp_parse_node_struct_t*)pn)->source_line);
    } else {
        printf("       ");
    }
    for (int i = 0; i < indent; i++) {
        printf(" ");
    }
    if (MP_PARSE_NODE_IS_NULL(pn)) {
        printf("NULL\n");
    } else if (MP_PARSE_NODE_IS_SMALL_INT(pn)) {
        machine_int_t arg = MP_PARSE_NODE_LEAF_SMALL_INT(pn);
        printf("int(" INT_FMT ")\n", arg);
    } else if (MP_PARSE_NODE_IS_LEAF(pn)) {
        machine_uint_t arg = MP_PARSE_NODE_LEAF_ARG(pn);
        switch (MP_PARSE_NODE_LEAF_KIND(pn)) {
            case MP_PARSE_NODE_ID: printf("id(%s)\n", qstr_str(arg)); break;
            case MP_PARSE_NODE_INTEGER: printf("int(%s)\n", qstr_str(arg)); break;
            case MP_PARSE_NODE_DECIMAL: printf("dec(%s)\n", qstr_str(arg)); break;
            case MP_PARSE_NODE_STRING: printf("str(%s)\n", qstr_str(arg)); break;
            case MP_PARSE_NODE_BYTES: printf("bytes(%s)\n", qstr_str(arg)); break;
            case MP_PARSE_NODE_TOKEN: printf("tok(" INT_FMT ")\n", arg); break;
            default: assert(0);
        }
    } else {
        // node must be a mp_parse_node_struct_t
        mp_parse_node_struct_t *pns = (mp_parse_node_struct_t*)pn;
        if (MP_PARSE_NODE_STRUCT_KIND(pns) == RULE_string) {
            printf("literal str(%.*s)\n", (int)pns->nodes[1], (char*)pns->nodes[0]);
        } else {
            uint n = MP_PARSE_NODE_STRUCT_NUM_NODES(pns);
#ifdef USE_RULE_NAME
            printf("%s(%d) (n=%d)\n", rules[MP_PARSE_NODE_STRUCT_KIND(pns)]->rule_name, MP_PARSE_NODE_STRUCT_KIND(pns), n);
#else
            printf("rule(%u) (n=%d)\n", (uint)MP_PARSE_NODE_STRUCT_KIND(pns), n);
#endif
            for (uint i = 0; i < n; i++) {
                mp_parse_node_print(pns->nodes[i], indent + 2);
            }
        }
    }
}
Exemple #13
0
scope_t *scope_new(scope_kind_t kind, mp_parse_node_t pn, qstr source_file, uint emit_options) {
    scope_t *scope = m_new0(scope_t, 1);
    scope->kind = kind;
    scope->pn = pn;
    scope->source_file = source_file;
    switch (kind) {
        case SCOPE_MODULE:
            scope->simple_name = MP_QSTR__lt_module_gt_;
            break;
        case SCOPE_FUNCTION:
        case SCOPE_CLASS:
            assert(MP_PARSE_NODE_IS_STRUCT(pn));
            scope->simple_name = MP_PARSE_NODE_LEAF_ARG(((mp_parse_node_struct_t*)pn)->nodes[0]);
            break;
        case SCOPE_LAMBDA:
            scope->simple_name = MP_QSTR__lt_lambda_gt_;
            break;
        case SCOPE_LIST_COMP:
            scope->simple_name = MP_QSTR__lt_listcomp_gt_;
            break;
        case SCOPE_DICT_COMP:
            scope->simple_name = MP_QSTR__lt_dictcomp_gt_;
            break;
        case SCOPE_SET_COMP:
            scope->simple_name = MP_QSTR__lt_setcomp_gt_;
            break;
        case SCOPE_GEN_EXPR:
            scope->simple_name = MP_QSTR__lt_genexpr_gt_;
            break;
        default:
            assert(0);
    }
    scope->raw_code = mp_emit_glue_new_raw_code();
    scope->emit_options = emit_options;
    scope->id_info_alloc = 8;
    scope->id_info = m_new(id_info_t, scope->id_info_alloc);

    return scope;
}
Exemple #14
0
STATIC bool fold_constants(parser_t *parser, const rule_t *rule, size_t num_args) {
    // this code does folding of arbitrary integer expressions, eg 1 + 2 * 3 + 4
    // it does not do partial folding, eg 1 + 2 + x -> 3 + x

    mp_obj_t arg0;
    if (rule->rule_id == RULE_expr
        || rule->rule_id == RULE_xor_expr
        || rule->rule_id == RULE_and_expr) {
        // folding for binary ops: | ^ &
        mp_parse_node_t pn = peek_result(parser, num_args - 1);
        if (!mp_parse_node_get_int_maybe(pn, &arg0)) {
            return false;
        }
        mp_binary_op_t op;
        if (rule->rule_id == RULE_expr) {
            op = MP_BINARY_OP_OR;
        } else if (rule->rule_id == RULE_xor_expr) {
            op = MP_BINARY_OP_XOR;
        } else {
            op = MP_BINARY_OP_AND;
        }
        for (ssize_t i = num_args - 2; i >= 0; --i) {
            pn = peek_result(parser, i);
            mp_obj_t arg1;
            if (!mp_parse_node_get_int_maybe(pn, &arg1)) {
                return false;
            }
            arg0 = mp_binary_op(op, arg0, arg1);
        }
    } else if (rule->rule_id == RULE_shift_expr
        || rule->rule_id == RULE_arith_expr
        || rule->rule_id == RULE_term) {
        // folding for binary ops: << >> + - * / % //
        mp_parse_node_t pn = peek_result(parser, num_args - 1);
        if (!mp_parse_node_get_int_maybe(pn, &arg0)) {
            return false;
        }
        for (ssize_t i = num_args - 2; i >= 1; i -= 2) {
            pn = peek_result(parser, i - 1);
            mp_obj_t arg1;
            if (!mp_parse_node_get_int_maybe(pn, &arg1)) {
                return false;
            }
            mp_token_kind_t tok = MP_PARSE_NODE_LEAF_ARG(peek_result(parser, i));
            static const uint8_t token_to_op[] = {
                MP_BINARY_OP_ADD,
                MP_BINARY_OP_SUBTRACT,
                MP_BINARY_OP_MULTIPLY,
                255,//MP_BINARY_OP_POWER,
                255,//MP_BINARY_OP_TRUE_DIVIDE,
                MP_BINARY_OP_FLOOR_DIVIDE,
                MP_BINARY_OP_MODULO,
                255,//MP_BINARY_OP_LESS
                MP_BINARY_OP_LSHIFT,
                255,//MP_BINARY_OP_MORE
                MP_BINARY_OP_RSHIFT,
            };
            mp_binary_op_t op = token_to_op[tok - MP_TOKEN_OP_PLUS];
            if (op == (mp_binary_op_t)255) {
                return false;
            }
            int rhs_sign = mp_obj_int_sign(arg1);
            if (op <= MP_BINARY_OP_RSHIFT) {
                // << and >> can't have negative rhs
                if (rhs_sign < 0) {
                    return false;
                }
            } else if (op >= MP_BINARY_OP_FLOOR_DIVIDE) {
                // % and // can't have zero rhs
                if (rhs_sign == 0) {
                    return false;
                }
            }
            arg0 = mp_binary_op(op, arg0, arg1);
        }
    } else if (rule->rule_id == RULE_factor_2) {
        // folding for unary ops: + - ~
        mp_parse_node_t pn = peek_result(parser, 0);
        if (!mp_parse_node_get_int_maybe(pn, &arg0)) {
            return false;
        }
        mp_token_kind_t tok = MP_PARSE_NODE_LEAF_ARG(peek_result(parser, 1));
        mp_unary_op_t op;
        if (tok == MP_TOKEN_OP_PLUS) {
            op = MP_UNARY_OP_POSITIVE;
        } else if (tok == MP_TOKEN_OP_MINUS) {
            op = MP_UNARY_OP_NEGATIVE;
        } else {
            assert(tok == MP_TOKEN_OP_TILDE); // should be
            op = MP_UNARY_OP_INVERT;
        }
        arg0 = mp_unary_op(op, arg0);

    #if MICROPY_COMP_CONST
    } else if (rule->rule_id == RULE_expr_stmt) {
        mp_parse_node_t pn1 = peek_result(parser, 0);
        if (!MP_PARSE_NODE_IS_NULL(pn1)
            && !(MP_PARSE_NODE_IS_STRUCT_KIND(pn1, RULE_expr_stmt_augassign)
            || MP_PARSE_NODE_IS_STRUCT_KIND(pn1, RULE_expr_stmt_assign_list))) {
            // this node is of the form <x> = <y>
            mp_parse_node_t pn0 = peek_result(parser, 1);
            if (MP_PARSE_NODE_IS_ID(pn0)
                && MP_PARSE_NODE_IS_STRUCT_KIND(pn1, RULE_atom_expr_normal)
                && MP_PARSE_NODE_IS_ID(((mp_parse_node_struct_t*)pn1)->nodes[0])
                && MP_PARSE_NODE_LEAF_ARG(((mp_parse_node_struct_t*)pn1)->nodes[0]) == MP_QSTR_const
                && MP_PARSE_NODE_IS_STRUCT_KIND(((mp_parse_node_struct_t*)pn1)->nodes[1], RULE_trailer_paren)
                ) {
                // code to assign dynamic constants: id = const(value)

                // get the id
                qstr id = MP_PARSE_NODE_LEAF_ARG(pn0);

                // get the value
                mp_parse_node_t pn_value = ((mp_parse_node_struct_t*)((mp_parse_node_struct_t*)pn1)->nodes[1])->nodes[0];
                mp_obj_t value;
                if (!mp_parse_node_get_int_maybe(pn_value, &value)) {
                    mp_obj_t exc = mp_obj_new_exception_msg(&mp_type_SyntaxError,
                        "constant must be an integer");
                    mp_obj_exception_add_traceback(exc, parser->lexer->source_name,
                        ((mp_parse_node_struct_t*)pn1)->source_line, MP_QSTR_NULL);
                    nlr_raise(exc);
                }

                // store the value in the table of dynamic constants
                mp_map_elem_t *elem = mp_map_lookup(&parser->consts, MP_OBJ_NEW_QSTR(id), MP_MAP_LOOKUP_ADD_IF_NOT_FOUND);
                assert(elem->value == MP_OBJ_NULL);
                elem->value = value;

                // If the constant starts with an underscore then treat it as a private
                // variable and don't emit any code to store the value to the id.
                if (qstr_str(id)[0] == '_') {
                    pop_result(parser); // pop const(value)
                    pop_result(parser); // pop id
                    push_result_rule(parser, 0, rules[RULE_pass_stmt], 0); // replace with "pass"
                    return true;
                }

                // replace const(value) with value
                pop_result(parser);
                push_result_node(parser, pn_value);

                // finished folding this assignment, but we still want it to be part of the tree
                return false;
            }
        }
        return false;
    #endif

    #if MICROPY_COMP_MODULE_CONST
    } else if (rule->rule_id == RULE_atom_expr_normal) {
        mp_parse_node_t pn0 = peek_result(parser, 1);
        mp_parse_node_t pn1 = peek_result(parser, 0);
        if (!(MP_PARSE_NODE_IS_ID(pn0)
            && MP_PARSE_NODE_IS_STRUCT_KIND(pn1, RULE_trailer_period))) {
            return false;
        }
        // id1.id2
        // look it up in constant table, see if it can be replaced with an integer
        mp_parse_node_struct_t *pns1 = (mp_parse_node_struct_t*)pn1;
        assert(MP_PARSE_NODE_IS_ID(pns1->nodes[0]));
        qstr q_base = MP_PARSE_NODE_LEAF_ARG(pn0);
        qstr q_attr = MP_PARSE_NODE_LEAF_ARG(pns1->nodes[0]);
        mp_map_elem_t *elem = mp_map_lookup((mp_map_t*)&mp_constants_map, MP_OBJ_NEW_QSTR(q_base), MP_MAP_LOOKUP);
        if (elem == NULL) {
            return false;
        }
        mp_obj_t dest[2];
        mp_load_method_maybe(elem->value, q_attr, dest);
        if (!(dest[0] != MP_OBJ_NULL && MP_OBJ_IS_INT(dest[0]) && dest[1] == MP_OBJ_NULL)) {
            return false;
        }
        arg0 = dest[0];
    #endif

    } else {
        return false;
    }

    // success folding this rule

    for (size_t i = num_args; i > 0; i--) {
        pop_result(parser);
    }
    if (MP_OBJ_IS_SMALL_INT(arg0)) {
        push_result_node(parser, mp_parse_node_new_small_int(MP_OBJ_SMALL_INT_VALUE(arg0)));
    } else {
        // TODO reuse memory for parse node struct?
        push_result_node(parser, make_node_const_object(parser, 0, arg0));
    }

    return true;
}