コード例 #1
0
ファイル: lexer.c プロジェクト: un33k/micropython
mp_lexer_t *mp_lexer_new(qstr src_name, void *stream_data, mp_lexer_stream_next_char_t stream_next_char, mp_lexer_stream_close_t stream_close) {
    mp_lexer_t *lex = m_new_maybe(mp_lexer_t, 1);

    // check for memory allocation error
    if (lex == NULL) {
        if (stream_close) {
            stream_close(stream_data);
        }
        return NULL;
    }

    lex->source_name = src_name;
    lex->stream_data = stream_data;
    lex->stream_next_char = stream_next_char;
    lex->stream_close = stream_close;
    lex->line = 1;
    lex->column = 1;
    lex->emit_dent = 0;
    lex->nested_bracket_level = 0;
    lex->alloc_indent_level = MICROPY_ALLOC_LEXER_INDENT_INIT;
    lex->num_indent_level = 1;
    lex->indent_level = m_new_maybe(uint16_t, lex->alloc_indent_level);
    vstr_init(&lex->vstr, 32);

    // check for memory allocation error
    if (lex->indent_level == NULL || vstr_had_error(&lex->vstr)) {
        mp_lexer_free(lex);
        return NULL;
    }

    // store sentinel for first indentation level
    lex->indent_level[0] = 0;

    // preload characters
    lex->chr0 = stream_next_char(stream_data);
    lex->chr1 = stream_next_char(stream_data);
    lex->chr2 = stream_next_char(stream_data);

    // if input stream is 0, 1 or 2 characters long and doesn't end in a newline, then insert a newline at the end
    if (lex->chr0 == MP_LEXER_CHAR_EOF) {
        lex->chr0 = '\n';
    } else if (lex->chr1 == MP_LEXER_CHAR_EOF) {
        if (lex->chr0 != '\n' && lex->chr0 != '\r') {
            lex->chr1 = '\n';
        }
    } else if (lex->chr2 == MP_LEXER_CHAR_EOF) {
        if (lex->chr1 != '\n' && lex->chr1 != '\r') {
            lex->chr2 = '\n';
        }
    }

    // preload first token
    mp_lexer_next_token_into(lex, &lex->tok_cur, true);

    return lex;
}
コード例 #2
0
ファイル: objexcept.c プロジェクト: cav71/micropython
void mp_obj_exception_add_traceback(mp_obj_t self_in, qstr file, size_t line, qstr block) {
    GET_NATIVE_EXCEPTION(self, self_in);

    // append this traceback info to traceback data
    // if memory allocation fails (eg because gc is locked), just return

    if (self->traceback_data == NULL) {
        self->traceback_data = m_new_maybe(size_t, 3);
        if (self->traceback_data == NULL) {
            return;
        }
        self->traceback_alloc = 3;
        self->traceback_len = 0;
    } else if (self->traceback_len + 3 > self->traceback_alloc) {
        // be conservative with growing traceback data
        size_t *tb_data = m_renew_maybe(size_t, self->traceback_data, self->traceback_alloc, self->traceback_alloc + 3, true);
        if (tb_data == NULL) {
            return;
        }
        self->traceback_data = tb_data;
        self->traceback_alloc += 3;
    }

    size_t *tb_data = &self->traceback_data[self->traceback_len];
    self->traceback_len += 3;
    tb_data[0] = file;
    tb_data[1] = line;
    tb_data[2] = block;
}
コード例 #3
0
ファイル: sdcard.c プロジェクト: learnforpractice/micropython
mp_uint_t sdcard_write_blocks(const uint8_t *src, uint32_t block_num, uint32_t num_blocks) {
    // check that SD card is initialised
    if (sd_handle.Instance == NULL) {
        return HAL_ERROR;
    }

    HAL_StatusTypeDef err = HAL_OK;

    // check that src pointer is aligned on a 4-byte boundary
    if (((uint32_t)src & 3) != 0) {
        // pointer is not aligned, so allocate a temporary block to do the write
        uint8_t *src_aligned = m_new_maybe(uint8_t, SDCARD_BLOCK_SIZE);
        if (src_aligned == NULL) {
            return HAL_ERROR;
        }
        for (size_t i = 0; i < num_blocks; ++i) {
            memcpy(src_aligned, src + i * SDCARD_BLOCK_SIZE, SDCARD_BLOCK_SIZE);
            err = sdcard_write_blocks(src_aligned, block_num + i, 1);
            if (err != HAL_OK) {
                break;
            }
        }
        m_del(uint8_t, src_aligned, SDCARD_BLOCK_SIZE);
        return err;
    }

    if (query_irq() == IRQ_STATE_ENABLED) {
        // we must disable USB irqs to prevent MSC contention with SD card
        uint32_t basepri = raise_irq_pri(IRQ_PRI_OTG_FS);

        #if SDIO_USE_GPDMA
        dma_init(&sd_tx_dma, &SDMMC_TX_DMA, &sd_handle);
        sd_handle.hdmatx = &sd_tx_dma;
        #endif

        // make sure cache is flushed to RAM so the DMA can read the correct data
        MP_HAL_CLEAN_DCACHE(src, num_blocks * SDCARD_BLOCK_SIZE);

        err = HAL_SD_WriteBlocks_DMA(&sd_handle, (uint8_t*)src, block_num, num_blocks);
        if (err == HAL_OK) {
            err = sdcard_wait_finished(&sd_handle, 60000);
        }

        #if SDIO_USE_GPDMA
        dma_deinit(&SDMMC_TX_DMA);
        sd_handle.hdmatx = NULL;
        #endif

        restore_irq_pri(basepri);
    } else {
        err = HAL_SD_WriteBlocks(&sd_handle, (uint8_t*)src, block_num, num_blocks, 60000);
        if (err == HAL_OK) {
            err = sdcard_wait_finished(&sd_handle, 60000);
        }
    }

    return err;
}
コード例 #4
0
ファイル: objexcept.c プロジェクト: GuyCarver/micropython-1
mp_obj_t mp_obj_new_exception_msg_varg(const mp_obj_type_t *exc_type, const char *fmt, ...) {
    assert(fmt != NULL);

    // Check that the given type is an exception type
    assert(exc_type->make_new == mp_obj_exception_make_new);

    // Try to allocate memory for the message
    mp_obj_str_t *o_str = m_new_obj_maybe(mp_obj_str_t);
    size_t o_str_alloc = strlen(fmt) + 1;
    byte *o_str_buf = m_new_maybe(byte, o_str_alloc);

    bool used_emg_buf = false;
    #if MICROPY_ENABLE_EMERGENCY_EXCEPTION_BUF
    // If memory allocation failed and there is an emergency buffer then try to use
    // that buffer to store the string object and its data (at least 16 bytes for
    // the string data), reserving room at the start for the traceback and 1-tuple.
    if ((o_str == NULL || o_str_buf == NULL)
        && mp_emergency_exception_buf_size >= EMG_TRACEBACK_ALLOC * sizeof(size_t)
            + sizeof(mp_obj_tuple_t) + sizeof(mp_obj_t) + sizeof(mp_obj_str_t) + 16) {
        used_emg_buf = true;
        o_str = (mp_obj_str_t*)((uint8_t*)MP_STATE_VM(mp_emergency_exception_buf)
            + EMG_TRACEBACK_ALLOC * sizeof(size_t) + sizeof(mp_obj_tuple_t) + sizeof(mp_obj_t));
        o_str_buf = (byte*)&o_str[1];
        o_str_alloc = (uint8_t*)MP_STATE_VM(mp_emergency_exception_buf)
            + mp_emergency_exception_buf_size - o_str_buf;
    }
    #endif

    if (o_str == NULL) {
        // No memory for the string object so create the exception with no args
        return mp_obj_exception_make_new(exc_type, 0, 0, NULL);
    }

    if (o_str_buf == NULL) {
        // No memory for the string buffer: assume that the fmt string is in ROM
        // and use that data as the data of the string
        o_str->len = o_str_alloc - 1; // will be equal to strlen(fmt)
        o_str->data = (const byte*)fmt;
    } else {
        // We have some memory to format the string
        struct _exc_printer_t exc_pr = {!used_emg_buf, o_str_alloc, 0, o_str_buf};
        mp_print_t print = {&exc_pr, exc_add_strn};
        va_list ap;
        va_start(ap, fmt);
        mp_vprintf(&print, fmt, ap);
        va_end(ap);
        exc_pr.buf[exc_pr.len] = '\0';
        o_str->len = exc_pr.len;
        o_str->data = exc_pr.buf;
    }

    // Create the string object and call mp_obj_exception_make_new to create the exception
    o_str->base.type = &mp_type_str;
    o_str->hash = qstr_compute_hash(o_str->data, o_str->len);
    mp_obj_t arg = MP_OBJ_FROM_PTR(o_str);
    return mp_obj_exception_make_new(exc_type, 1, 0, &arg);
}
コード例 #5
0
ファイル: objexcept.c プロジェクト: GuyCarver/micropython-1
void mp_obj_exception_add_traceback(mp_obj_t self_in, qstr file, size_t line, qstr block) {
    GET_NATIVE_EXCEPTION(self, self_in);

    // append this traceback info to traceback data
    // if memory allocation fails (eg because gc is locked), just return

    if (self->traceback_data == NULL) {
        self->traceback_data = m_new_maybe(size_t, TRACEBACK_ENTRY_LEN);
        if (self->traceback_data == NULL) {
            #if MICROPY_ENABLE_EMERGENCY_EXCEPTION_BUF
            if (mp_emergency_exception_buf_size >= EMG_TRACEBACK_ALLOC * sizeof(size_t)) {
                // There is room in the emergency buffer for traceback data
                size_t *tb = (size_t*)MP_STATE_VM(mp_emergency_exception_buf);
                self->traceback_data = tb;
                self->traceback_alloc = EMG_TRACEBACK_ALLOC;
            } else {
                // Can't allocate and no room in emergency buffer
                return;
            }
            #else
            // Can't allocate
            return;
            #endif
        } else {
            // Allocated the traceback data on the heap
            self->traceback_alloc = TRACEBACK_ENTRY_LEN;
        }
        self->traceback_len = 0;
    } else if (self->traceback_len + TRACEBACK_ENTRY_LEN > self->traceback_alloc) {
        #if MICROPY_ENABLE_EMERGENCY_EXCEPTION_BUF
        if (self->traceback_data == (size_t*)MP_STATE_VM(mp_emergency_exception_buf)) {
            // Can't resize the emergency buffer
            return;
        }
        #endif
        // be conservative with growing traceback data
        size_t *tb_data = m_renew_maybe(size_t, self->traceback_data, self->traceback_alloc,
            self->traceback_alloc + TRACEBACK_ENTRY_LEN, true);
        if (tb_data == NULL) {
            return;
        }
        self->traceback_data = tb_data;
        self->traceback_alloc += TRACEBACK_ENTRY_LEN;
    }

    size_t *tb_data = &self->traceback_data[self->traceback_len];
    self->traceback_len += TRACEBACK_ENTRY_LEN;
    tb_data[0] = file;
    tb_data[1] = line;
    tb_data[2] = block;
}
コード例 #6
0
ファイル: sdcard.c プロジェクト: DiegoAltamirano/micropython
mp_uint_t sdcard_write_blocks(const uint8_t *src, uint32_t block_num, uint32_t num_blocks) {
    // check that SD card is initialised
    if (sd_handle.Instance == NULL) {
        return SD_ERROR;
    }

    HAL_SD_ErrorTypedef err = SD_OK;

    // check that src pointer is aligned on a 4-byte boundary
    if (((uint32_t)src & 3) != 0) {
        // pointer is not aligned, so allocate a temporary block to do the write
        uint8_t *src_aligned = m_new_maybe(uint8_t, SDCARD_BLOCK_SIZE);
        if (src_aligned == NULL) {
            return SD_ERROR;
        }
        for (size_t i = 0; i < num_blocks; ++i) {
            memcpy(src_aligned, src + i * SDCARD_BLOCK_SIZE, SDCARD_BLOCK_SIZE);
            err = sdcard_write_blocks(src_aligned, block_num + i, 1);
            if (err != SD_OK) {
                break;
            }
        }
        m_del(uint8_t, src_aligned, SDCARD_BLOCK_SIZE);
        return err;
    }

    if (query_irq() == IRQ_STATE_ENABLED) {
        // we must disable USB irqs to prevent MSC contention with SD card
        uint32_t basepri = raise_irq_pri(IRQ_PRI_OTG_FS);

        dma_init(&sd_tx_dma, &dma_SDIO_0_TX, &sd_handle);
        sd_handle.hdmatx = &sd_tx_dma;

        err = HAL_SD_WriteBlocks_BlockNumber_DMA(&sd_handle, (uint32_t*)src, block_num, SDCARD_BLOCK_SIZE, num_blocks);
        if (err == SD_OK) {
            // wait for DMA transfer to finish, with a large timeout
            err = HAL_SD_CheckWriteOperation(&sd_handle, 100000000);
        }
        dma_deinit(&dma_SDIO_0_TX);
        sd_handle.hdmatx = NULL;

        restore_irq_pri(basepri);
    } else {
        err = HAL_SD_WriteBlocks_BlockNumber(&sd_handle, (uint32_t*)src, block_num, SDCARD_BLOCK_SIZE, num_blocks);
    }

    return err;
}
コード例 #7
0
ファイル: parse.c プロジェクト: 19emtuck/micropython
mp_parse_tree_t mp_parse(mp_lexer_t *lex, mp_parse_input_kind_t input_kind) {

    // initialise parser and allocate memory for its stacks

    parser_t parser;

    parser.parse_error = PARSE_ERROR_NONE;

    parser.rule_stack_alloc = MICROPY_ALLOC_PARSE_RULE_INIT;
    parser.rule_stack_top = 0;
    parser.rule_stack = m_new_maybe(rule_stack_t, parser.rule_stack_alloc);

    parser.result_stack_alloc = MICROPY_ALLOC_PARSE_RESULT_INIT;
    parser.result_stack_top = 0;
    parser.result_stack = m_new_maybe(mp_parse_node_t, parser.result_stack_alloc);

    parser.lexer = lex;

    parser.tree.chunk = NULL;
    parser.cur_chunk = NULL;

    #if MICROPY_COMP_CONST
    mp_map_init(&parser.consts, 0);
    #endif

    // check if we could allocate the stacks
    if (parser.rule_stack == NULL || parser.result_stack == NULL) {
        goto memory_error;
    }

    // work out the top-level rule to use, and push it on the stack
    size_t top_level_rule;
    switch (input_kind) {
        case MP_PARSE_SINGLE_INPUT: top_level_rule = RULE_single_input; break;
        case MP_PARSE_EVAL_INPUT: top_level_rule = RULE_eval_input; break;
        default: top_level_rule = RULE_file_input;
    }
    push_rule(&parser, lex->tok_line, rules[top_level_rule], 0);

    // parse!

    size_t n, i; // state for the current rule
    size_t rule_src_line; // source line for the first token matched by the current rule
    bool backtrack = false;
    const rule_t *rule = NULL;

    for (;;) {
        next_rule:
        if (parser.rule_stack_top == 0 || parser.parse_error) {
            break;
        }

        pop_rule(&parser, &rule, &i, &rule_src_line);
        n = rule->act & RULE_ACT_ARG_MASK;

        /*
        // debugging
        printf("depth=%d ", parser.rule_stack_top);
        for (int j = 0; j < parser.rule_stack_top; ++j) {
            printf(" ");
        }
        printf("%s n=%d i=%d bt=%d\n", rule->rule_name, n, i, backtrack);
        */

        switch (rule->act & RULE_ACT_KIND_MASK) {
            case RULE_ACT_OR:
                if (i > 0 && !backtrack) {
                    goto next_rule;
                } else {
                    backtrack = false;
                }
                for (; i < n; ++i) {
                    uint16_t kind = rule->arg[i] & RULE_ARG_KIND_MASK;
                    if (kind == RULE_ARG_TOK) {
                        if (lex->tok_kind == (rule->arg[i] & RULE_ARG_ARG_MASK)) {
                            push_result_token(&parser);
                            mp_lexer_to_next(lex);
                            goto next_rule;
                        }
                    } else {
                        assert(kind == RULE_ARG_RULE);
                        if (i + 1 < n) {
                            push_rule(&parser, rule_src_line, rule, i + 1); // save this or-rule
                        }
                        push_rule_from_arg(&parser, rule->arg[i]); // push child of or-rule
                        goto next_rule;
                    }
                }
                backtrack = true;
                break;

            case RULE_ACT_AND: {

                // failed, backtrack if we can, else syntax error
                if (backtrack) {
                    assert(i > 0);
                    if ((rule->arg[i - 1] & RULE_ARG_KIND_MASK) == RULE_ARG_OPT_RULE) {
                        // an optional rule that failed, so continue with next arg
                        push_result_node(&parser, MP_PARSE_NODE_NULL);
                        backtrack = false;
                    } else {
                        // a mandatory rule that failed, so propagate backtrack
                        if (i > 1) {
                            // already eaten tokens so can't backtrack
                            goto syntax_error;
                        } else {
                            goto next_rule;
                        }
                    }
                }

                // progress through the rule
                for (; i < n; ++i) {
                    switch (rule->arg[i] & RULE_ARG_KIND_MASK) {
                        case RULE_ARG_TOK: {
                            // need to match a token
                            mp_token_kind_t tok_kind = rule->arg[i] & RULE_ARG_ARG_MASK;
                            if (lex->tok_kind == tok_kind) {
                                // matched token
                                if (tok_kind == MP_TOKEN_NAME) {
                                    push_result_token(&parser);
                                }
                                mp_lexer_to_next(lex);
                            } else {
                                // failed to match token
                                if (i > 0) {
                                    // already eaten tokens so can't backtrack
                                    goto syntax_error;
                                } else {
                                    // this rule failed, so backtrack
                                    backtrack = true;
                                    goto next_rule;
                                }
                            }
                            break;
                        }
                        case RULE_ARG_RULE:
                        case RULE_ARG_OPT_RULE:
                        rule_and_no_other_choice:
                            push_rule(&parser, rule_src_line, rule, i + 1); // save this and-rule
                            push_rule_from_arg(&parser, rule->arg[i]); // push child of and-rule
                            goto next_rule;
                        default:
                            assert(0);
                            goto rule_and_no_other_choice; // to help flow control analysis
                    }
                }

                assert(i == n);

                // matched the rule, so now build the corresponding parse_node

                #if !MICROPY_ENABLE_DOC_STRING
                // this code discards lonely statements, such as doc strings
                if (input_kind != MP_PARSE_SINGLE_INPUT && rule->rule_id == RULE_expr_stmt && peek_result(&parser, 0) == MP_PARSE_NODE_NULL) {
                    mp_parse_node_t p = peek_result(&parser, 1);
                    if ((MP_PARSE_NODE_IS_LEAF(p) && !MP_PARSE_NODE_IS_ID(p)) || MP_PARSE_NODE_IS_STRUCT_KIND(p, RULE_string)) {
                        pop_result(&parser); // MP_PARSE_NODE_NULL
                        mp_parse_node_t pn = pop_result(&parser); // possibly RULE_string
                        if (MP_PARSE_NODE_IS_STRUCT(pn)) {
                            mp_parse_node_struct_t *pns = (mp_parse_node_struct_t *)pn;
                            if (MP_PARSE_NODE_STRUCT_KIND(pns) == RULE_string) {
                                m_del(char, (char*)pns->nodes[0], (size_t)pns->nodes[1]);
                            }
                        }
                        push_result_rule(&parser, rule_src_line, rules[RULE_pass_stmt], 0);
                        break;
                    }
                }
                #endif

                // count number of arguments for the parse node
                i = 0;
                size_t num_not_nil = 0;
                for (size_t x = n; x > 0;) {
                    --x;
                    if ((rule->arg[x] & RULE_ARG_KIND_MASK) == RULE_ARG_TOK) {
                        mp_token_kind_t tok_kind = rule->arg[x] & RULE_ARG_ARG_MASK;
                        if (tok_kind == MP_TOKEN_NAME) {
                            // only tokens which were names are pushed to stack
                            i += 1;
                            num_not_nil += 1;
                        }
                    } else {
                        // rules are always pushed
                        if (peek_result(&parser, i) != MP_PARSE_NODE_NULL) {
                            num_not_nil += 1;
                        }
                        i += 1;
                    }
                }

                if (num_not_nil == 1 && (rule->act & RULE_ACT_ALLOW_IDENT)) {
                    // this rule has only 1 argument and should not be emitted
                    mp_parse_node_t pn = MP_PARSE_NODE_NULL;
                    for (size_t x = 0; x < i; ++x) {
                        mp_parse_node_t pn2 = pop_result(&parser);
                        if (pn2 != MP_PARSE_NODE_NULL) {
                            pn = pn2;
                        }
                    }
                    push_result_node(&parser, pn);
                } else {
                    // this rule must be emitted

                    if (rule->act & RULE_ACT_ADD_BLANK) {
                        // and add an extra blank node at the end (used by the compiler to store data)
                        push_result_node(&parser, MP_PARSE_NODE_NULL);
                        i += 1;
                    }

                    push_result_rule(&parser, rule_src_line, rule, i);
                }
                break;
            }
コード例 #8
0
ファイル: parse.c プロジェクト: Metallicow/micropython
mp_parse_node_t mp_parse(mp_lexer_t *lex, mp_parse_input_kind_t input_kind, mp_parse_error_kind_t *parse_error_kind_out) {

    // initialise parser and allocate memory for its stacks

    parser_t parser;

    parser.had_memory_error = false;

    parser.rule_stack_alloc = MICROPY_ALLOC_PARSE_RULE_INIT;
    parser.rule_stack_top = 0;
    parser.rule_stack = m_new_maybe(rule_stack_t, parser.rule_stack_alloc);

    parser.result_stack_alloc = MICROPY_ALLOC_PARSE_RESULT_INIT;
    parser.result_stack_top = 0;
    parser.result_stack = m_new_maybe(mp_parse_node_t, parser.result_stack_alloc);

    parser.lexer = lex;

    // check if we could allocate the stacks
    if (parser.rule_stack == NULL || parser.result_stack == NULL) {
        goto memory_error;
    }

    // work out the top-level rule to use, and push it on the stack
    int top_level_rule;
    switch (input_kind) {
        case MP_PARSE_SINGLE_INPUT: top_level_rule = RULE_single_input; break;
        case MP_PARSE_EVAL_INPUT: top_level_rule = RULE_eval_input; break;
        default: top_level_rule = RULE_file_input;
    }
    push_rule(&parser, mp_lexer_cur(lex)->src_line, rules[top_level_rule], 0);

    // parse!

    uint n, i; // state for the current rule
    uint rule_src_line; // source line for the first token matched by the current rule
    bool backtrack = false;
    const rule_t *rule = NULL;
    mp_token_kind_t tok_kind;
    bool emit_rule;
    bool had_trailing_sep;

    for (;;) {
        next_rule:
        if (parser.rule_stack_top == 0 || parser.had_memory_error) {
            break;
        }

        pop_rule(&parser, &rule, &i, &rule_src_line);
        n = rule->act & RULE_ACT_ARG_MASK;

        /*
        // debugging
        printf("depth=%d ", parser.rule_stack_top);
        for (int j = 0; j < parser.rule_stack_top; ++j) {
            printf(" ");
        }
        printf("%s n=%d i=%d bt=%d\n", rule->rule_name, n, i, backtrack);
        */

        switch (rule->act & RULE_ACT_KIND_MASK) {
            case RULE_ACT_OR:
                if (i > 0 && !backtrack) {
                    goto next_rule;
                } else {
                    backtrack = false;
                }
                for (; i < n - 1; ++i) {
                    switch (rule->arg[i] & RULE_ARG_KIND_MASK) {
                        case RULE_ARG_TOK:
                            if (mp_lexer_is_kind(lex, rule->arg[i] & RULE_ARG_ARG_MASK)) {
                                push_result_token(&parser, lex);
                                mp_lexer_to_next(lex);
                                goto next_rule;
                            }
                            break;
                        case RULE_ARG_RULE:
                            push_rule(&parser, rule_src_line, rule, i + 1); // save this or-rule
                            push_rule_from_arg(&parser, rule->arg[i]); // push child of or-rule
                            goto next_rule;
                        default:
                            assert(0);
                    }
                }
                if ((rule->arg[i] & RULE_ARG_KIND_MASK) == RULE_ARG_TOK) {
                    if (mp_lexer_is_kind(lex, rule->arg[i] & RULE_ARG_ARG_MASK)) {
                        push_result_token(&parser, lex);
                        mp_lexer_to_next(lex);
                    } else {
                        backtrack = true;
                        goto next_rule;
                    }
                } else {
                    push_rule_from_arg(&parser, rule->arg[i]);
                }
                break;

            case RULE_ACT_AND:

                // failed, backtrack if we can, else syntax error
                if (backtrack) {
                    assert(i > 0);
                    if ((rule->arg[i - 1] & RULE_ARG_KIND_MASK) == RULE_ARG_OPT_RULE) {
                        // an optional rule that failed, so continue with next arg
                        push_result_node(&parser, MP_PARSE_NODE_NULL);
                        backtrack = false;
                    } else {
                        // a mandatory rule that failed, so propagate backtrack
                        if (i > 1) {
                            // already eaten tokens so can't backtrack
                            goto syntax_error;
                        } else {
                            goto next_rule;
                        }
                    }
                }

                // progress through the rule
                for (; i < n; ++i) {
                    switch (rule->arg[i] & RULE_ARG_KIND_MASK) {
                        case RULE_ARG_TOK:
                            // need to match a token
                            tok_kind = rule->arg[i] & RULE_ARG_ARG_MASK;
                            if (mp_lexer_is_kind(lex, tok_kind)) {
                                // matched token
                                if (tok_kind == MP_TOKEN_NAME) {
                                    push_result_token(&parser, lex);
                                }
                                mp_lexer_to_next(lex);
                            } else {
                                // failed to match token
                                if (i > 0) {
                                    // already eaten tokens so can't backtrack
                                    goto syntax_error;
                                } else {
                                    // this rule failed, so backtrack
                                    backtrack = true;
                                    goto next_rule;
                                }
                            }
                            break;
                        case RULE_ARG_RULE:
                        case RULE_ARG_OPT_RULE:
                            push_rule(&parser, rule_src_line, rule, i + 1); // save this and-rule
                            push_rule_from_arg(&parser, rule->arg[i]); // push child of and-rule
                            goto next_rule;
                        default:
                            assert(0);
                    }
                }

                assert(i == n);

                // matched the rule, so now build the corresponding parse_node

                // count number of arguments for the parse_node
                i = 0;
                emit_rule = false;
                for (int x = 0; x < n; ++x) {
                    if ((rule->arg[x] & RULE_ARG_KIND_MASK) == RULE_ARG_TOK) {
                        tok_kind = rule->arg[x] & RULE_ARG_ARG_MASK;
                        if (tok_kind >= MP_TOKEN_NAME) {
                            emit_rule = true;
                        }
                        if (tok_kind == MP_TOKEN_NAME) {
                            // only tokens which were names are pushed to stack
                            i += 1;
                        }
                    } else {
                        // rules are always pushed
                        i += 1;
                    }
                }

#if !MICROPY_EMIT_CPYTHON && !MICROPY_ENABLE_DOC_STRING
                // this code discards lonely statements, such as doc strings
                if (input_kind != MP_PARSE_SINGLE_INPUT && rule->rule_id == RULE_expr_stmt && peek_result(&parser, 0) == MP_PARSE_NODE_NULL) {
                    mp_parse_node_t p = peek_result(&parser, 1);
                    if ((MP_PARSE_NODE_IS_LEAF(p) && !MP_PARSE_NODE_IS_ID(p)) || MP_PARSE_NODE_IS_STRUCT_KIND(p, RULE_string)) {
                        pop_result(&parser);
                        pop_result(&parser);
                        push_result_rule(&parser, rule_src_line, rules[RULE_pass_stmt], 0);
                        break;
                    }
                }
#endif

                // always emit these rules, even if they have only 1 argument
                if (rule->rule_id == RULE_expr_stmt || rule->rule_id == RULE_yield_stmt) {
                    emit_rule = true;
                }

                // never emit these rules if they have only 1 argument
                // NOTE: can't put atom_paren here because we need it to distinguisg, for example, [a,b] from [(a,b)]
                // TODO possibly put varargslist_name, varargslist_equal here as well
                if (rule->rule_id == RULE_else_stmt || rule->rule_id == RULE_testlist_comp_3b || rule->rule_id == RULE_import_as_names_paren || rule->rule_id == RULE_typedargslist_name || rule->rule_id == RULE_typedargslist_colon || rule->rule_id == RULE_typedargslist_equal || rule->rule_id == RULE_dictorsetmaker_colon || rule->rule_id == RULE_classdef_2 || rule->rule_id == RULE_with_item_as || rule->rule_id == RULE_assert_stmt_extra || rule->rule_id == RULE_as_name || rule->rule_id == RULE_raise_stmt_from || rule->rule_id == RULE_vfpdef) {
                    emit_rule = false;
                }

                // always emit these rules, and add an extra blank node at the end (to be used by the compiler to store data)
                if (ADD_BLANK_NODE(rule->rule_id)) {
                    emit_rule = true;
                    push_result_node(&parser, MP_PARSE_NODE_NULL);
                    i += 1;
                }

                int num_not_nil = 0;
                for (int x = 0; x < i; ++x) {
                    if (peek_result(&parser, x) != MP_PARSE_NODE_NULL) {
                        num_not_nil += 1;
                    }
                }
                //printf("done and %s n=%d i=%d notnil=%d\n", rule->rule_name, n, i, num_not_nil);
                if (emit_rule) {
                    push_result_rule(&parser, rule_src_line, rule, i);
                } else if (num_not_nil == 0) {
                    push_result_rule(&parser, rule_src_line, rule, i); // needed for, eg, atom_paren, testlist_comp_3b
                    //result_stack_show(parser);
                    //assert(0);
                } else if (num_not_nil == 1) {
                    // single result, leave it on stack
                    mp_parse_node_t pn = MP_PARSE_NODE_NULL;
                    for (int x = 0; x < i; ++x) {
                        mp_parse_node_t pn2 = pop_result(&parser);
                        if (pn2 != MP_PARSE_NODE_NULL) {
                            pn = pn2;
                        }
                    }
                    push_result_node(&parser, pn);
                } else {
                    push_result_rule(&parser, rule_src_line, rule, i);
                }
                break;

            case RULE_ACT_LIST:
                // n=2 is: item item*
                // n=1 is: item (sep item)*
                // n=3 is: item (sep item)* [sep]
                if (backtrack) {
                    list_backtrack:
                    had_trailing_sep = false;
                    if (n == 2) {
                        if (i == 1) {
                            // fail on item, first time round; propagate backtrack
                            goto next_rule;
                        } else {
                            // fail on item, in later rounds; finish with this rule
                            backtrack = false;
                        }
                    } else {
                        if (i == 1) {
                            // fail on item, first time round; propagate backtrack
                            goto next_rule;
                        } else if ((i & 1) == 1) {
                            // fail on item, in later rounds; have eaten tokens so can't backtrack
                            if (n == 3) {
                                // list allows trailing separator; finish parsing list
                                had_trailing_sep = true;
                                backtrack = false;
                            } else {
                                // list doesn't allowing trailing separator; fail
                                goto syntax_error;
                            }
                        } else {
                            // fail on separator; finish parsing list
                            backtrack = false;
                        }
                    }
                } else {
                    for (;;) {
                        uint arg = rule->arg[i & 1 & n];
                        switch (arg & RULE_ARG_KIND_MASK) {
                            case RULE_ARG_TOK:
                                if (mp_lexer_is_kind(lex, arg & RULE_ARG_ARG_MASK)) {
                                    if (i & 1 & n) {
                                        // separators which are tokens are not pushed to result stack
                                    } else {
                                        push_result_token(&parser, lex);
                                    }
                                    mp_lexer_to_next(lex);
                                    // got element of list, so continue parsing list
                                    i += 1;
                                } else {
                                    // couldn't get element of list
                                    i += 1;
                                    backtrack = true;
                                    goto list_backtrack;
                                }
                                break;
                            case RULE_ARG_RULE:
                                push_rule(&parser, rule_src_line, rule, i + 1); // save this list-rule
                                push_rule_from_arg(&parser, arg); // push child of list-rule
                                goto next_rule;
                            default:
                                assert(0);
                        }
                    }
                }
                assert(i >= 1);

                // compute number of elements in list, result in i
                i -= 1;
                if ((n & 1) && (rule->arg[1] & RULE_ARG_KIND_MASK) == RULE_ARG_TOK) {
                    // don't count separators when they are tokens
                    i = (i + 1) / 2;
                }

                if (i == 1) {
                    // list matched single item
                    if (had_trailing_sep) {
                        // if there was a trailing separator, make a list of a single item
                        push_result_rule(&parser, rule_src_line, rule, i);
                    } else {
                        // just leave single item on stack (ie don't wrap in a list)
                    }
                } else {
                    //printf("done list %s %d %d\n", rule->rule_name, n, i);
                    push_result_rule(&parser, rule_src_line, rule, i);
                }
                break;

            default:
                assert(0);
        }
    }

    mp_parse_node_t result;

    // check if we had a memory error
    if (parser.had_memory_error) {
memory_error:
        *parse_error_kind_out = MP_PARSE_ERROR_MEMORY;
        result = MP_PARSE_NODE_NULL;
        goto finished;

    }

    // check we are at the end of the token stream
    if (!mp_lexer_is_kind(lex, MP_TOKEN_END)) {
        goto syntax_error;
    }

    //printf("--------------\n");
    //result_stack_show(parser);
    //printf("rule stack alloc: %d\n", parser.rule_stack_alloc);
    //printf("result stack alloc: %d\n", parser.result_stack_alloc);
    //printf("number of parse nodes allocated: %d\n", num_parse_nodes_allocated);

    // get the root parse node that we created
    assert(parser.result_stack_top == 1);
    result = parser.result_stack[0];

finished:
    // free the memory that we don't need anymore
    m_del(rule_stack_t, parser.rule_stack, parser.rule_stack_alloc);
    m_del(mp_parse_node_t, parser.result_stack, parser.result_stack_alloc);

    // return the result
    return result;

syntax_error:
    if (mp_lexer_is_kind(lex, MP_TOKEN_INDENT)) {
        *parse_error_kind_out = MP_PARSE_ERROR_UNEXPECTED_INDENT;
    } else if (mp_lexer_is_kind(lex, MP_TOKEN_DEDENT_MISMATCH)) {
        *parse_error_kind_out = MP_PARSE_ERROR_UNMATCHED_UNINDENT;
    } else {
        *parse_error_kind_out = MP_PARSE_ERROR_INVALID_SYNTAX;
#ifdef USE_RULE_NAME
        // debugging: print the rule name that failed and the token
        printf("rule: %s\n", rule->rule_name);
#if MICROPY_DEBUG_PRINTERS
        mp_token_show(mp_lexer_cur(lex));
#endif
#endif
    }
    result = MP_PARSE_NODE_NULL;
    goto finished;
}