/*
 * This file is part of the MicroPython project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2013-2017 Damien P. George
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <unistd.h> // for ssize_t
#include <assert.h>
#include <string.h>

#include "py/lexer.h"
#include "py/parse.h"
#include "py/parsenum.h"
#include "py/runtime.h"
#include "py/objint.h"
#include "py/objstr.h"
#include "py/builtin.h"

#if MICROPY_ENABLE_COMPILER

#define RULE_ACT_ARG_MASK (0x0f)
#define RULE_ACT_KIND_MASK (0x30)
#define RULE_ACT_ALLOW_IDENT (0x40)
#define RULE_ACT_ADD_BLANK (0x80)
#define RULE_ACT_OR (0x10) //语法规则或的关系
#define RULE_ACT_AND (0x20) //语法规则与的关系
#define RULE_ACT_LIST (0x30) //语法规则并列的关系

#define RULE_ARG_KIND_MASK (0xf000)
#define RULE_ARG_ARG_MASK (0x0fff)
#define RULE_ARG_TOK (0x1000)
#define RULE_ARG_RULE (0x2000)
#define RULE_ARG_OPT_RULE (0x3000)

// 下面这行为调试输出语法规则名称用,如果不需要注释掉这行。
#define USE_RULE_NAME (1)

enum {
// define rules with a compile function
#define DEF_RULE(rule, comp, kind, ...) RULE_##rule,
#define DEF_RULE_NC(rule, kind, ...)
#include "py/grammar.h"
#undef DEF_RULE
#undef DEF_RULE_NC
 RULE_const_object, // special node for a constant, generic Python object

// define rules without a compile function
#define DEF_RULE(rule, comp, kind, ...)
#define DEF_RULE_NC(rule, kind, ...) RULE_##rule,
#include "py/grammar.h"
#undef DEF_RULE
#undef DEF_RULE_NC
};

// 定义每条规则执行的动作数组
STATIC const uint8_t rule_act_table[] = {
#define or(n) (RULE_ACT_OR | n)
#define and(n) (RULE_ACT_AND | n)
#define and_ident(n) (RULE_ACT_AND | n | RULE_ACT_ALLOW_IDENT)
#define and_blank(n) (RULE_ACT_AND | n | RULE_ACT_ADD_BLANK)
#define one_or_more (RULE_ACT_LIST | 2)
#define list (RULE_ACT_LIST | 1)
#define list_with_end (RULE_ACT_LIST | 3)

#define DEF_RULE(rule, comp, kind, ...) kind,
#define DEF_RULE_NC(rule, kind, ...)
#include "py/grammar.h"
#undef DEF_RULE
#undef DEF_RULE_NC

 0, // RULE_const_object

#define DEF_RULE(rule, comp, kind, ...)
#define DEF_RULE_NC(rule, kind, ...) kind,
#include "py/grammar.h"
#undef DEF_RULE
#undef DEF_RULE_NC

#undef or
#undef and
#undef and_ident
#undef and_blank
#undef one_or_more
#undef list
#undef list_with_end
};

// 定义每条规则的参数数组。
STATIC const uint16_t rule_arg_combined_table[] = {
#define tok(t) (RULE_ARG_TOK | MP_TOKEN_##t)
#define rule(r) (RULE_ARG_RULE | RULE_##r)
#define opt_rule(r) (RULE_ARG_OPT_RULE | RULE_##r)

#define DEF_RULE(rule, comp, kind, ...) __VA_ARGS__,
#define DEF_RULE_NC(rule, kind, ...)
#include "py/grammar.h"
#undef DEF_RULE
#undef DEF_RULE_NC

#define DEF_RULE(rule, comp, kind, ...)
#define DEF_RULE_NC(rule, kind, ...) __VA_ARGS__,
#include "py/grammar.h"
#undef DEF_RULE
#undef DEF_RULE_NC

#undef tok
#undef rule
#undef opt_rule
};

// Macro to create a list of N identifiers where N is the number of variable arguments to the macro
#define RULE_EXPAND(x) x
#define RULE_PADDING(rule, ...) RULE_PADDING2(rule, __VA_ARGS__, RULE_PADDING_IDS(rule))
#define RULE_PADDING2(rule, ...) RULE_EXPAND(RULE_PADDING3(rule, __VA_ARGS__))
#define RULE_PADDING3(rule, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, ...) __VA_ARGS__
#define RULE_PADDING_IDS(r) PAD12_##r, PAD11_##r, PAD10_##r, PAD9_##r, PAD8_##r, PAD7_##r, PAD6_##r, PAD5_##r, PAD4_##r, PAD3_##r, PAD2_##r, PAD1_##r,

// Use an enum to create constants specifying how much room a rule takes in rule_arg_combined_table
enum {
#define DEF_RULE(rule, comp, kind, ...) RULE_PADDING(rule, __VA_ARGS__)
#define DEF_RULE_NC(rule, kind, ...)
#include "py/grammar.h"
#undef DEF_RULE
#undef DEF_RULE_NC
#define DEF_RULE(rule, comp, kind, ...)
#define DEF_RULE_NC(rule, kind, ...) RULE_PADDING(rule, __VA_ARGS__)
#include "py/grammar.h"
#undef DEF_RULE
#undef DEF_RULE_NC
};

// 用来计算rule_arg_combined_table表格里参数开始的位置的宏
#define RULE_ARG_OFFSET(rule, ...) RULE_ARG_OFFSET2(rule, __VA_ARGS__, RULE_ARG_OFFSET_IDS(rule))
#define RULE_ARG_OFFSET2(rule, ...) RULE_EXPAND(RULE_ARG_OFFSET3(rule, __VA_ARGS__))
#define RULE_ARG_OFFSET3(rule, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, ...) _13
#define RULE_ARG_OFFSET_IDS(r) PAD12_##r, PAD11_##r, PAD10_##r, PAD9_##r, PAD8_##r, PAD7_##r, PAD6_##r, PAD5_##r, PAD4_##r, PAD3_##r, PAD2_##r, PAD1_##r, PAD0_##r,

// Use the above enum values to create a table of offsets for each rule's arg
// data, which indexes rule_arg_combined_table. The offsets require 9 bits of
// storage but only the lower 8 bits are stored here. The 9th bit is computed
// in get_rule_arg using the FIRST_RULE_WITH_OFFSET_ABOVE_255 constant.
STATIC const uint8_t rule_arg_offset_table[] = {
#define DEF_RULE(rule, comp, kind, ...) RULE_ARG_OFFSET(rule, __VA_ARGS__) & 0xff,
#define DEF_RULE_NC(rule, kind, ...)
#include "py/grammar.h"
#undef DEF_RULE
#undef DEF_RULE_NC
 0, // RULE_const_object
#define DEF_RULE(rule, comp, kind, ...)
#define DEF_RULE_NC(rule, kind, ...) RULE_ARG_OFFSET(rule, __VA_ARGS__) & 0xff,
#include "py/grammar.h"
#undef DEF_RULE
#undef DEF_RULE_NC
};

// Define a constant that's used to determine the 9th bit of the values in rule_arg_offset_table
static const size_t FIRST_RULE_WITH_OFFSET_ABOVE_255 =
#define DEF_RULE(rule, comp, kind, ...) RULE_ARG_OFFSET(rule, __VA_ARGS__) >= 0x100 ? RULE_##rule :
#define DEF_RULE_NC(rule, kind, ...)
#include "py/grammar.h"
#undef DEF_RULE
#undef DEF_RULE_NC
#define DEF_RULE(rule, comp, kind, ...)
#define DEF_RULE_NC(rule, kind, ...) RULE_ARG_OFFSET(rule, __VA_ARGS__) >= 0x100 ? RULE_##rule :
#include "py/grammar.h"
#undef DEF_RULE
#undef DEF_RULE_NC
0;

#if USE_RULE_NAME
// Define an array of rule names corresponding to each rule
STATIC const char *const rule_name_table[] = {
#define DEF_RULE(rule, comp, kind, ...) #rule,
#define DEF_RULE_NC(rule, kind, ...)
#include "py/grammar.h"
#undef DEF_RULE
#undef DEF_RULE_NC
 "", // RULE_const_object
#define DEF_RULE(rule, comp, kind, ...)
#define DEF_RULE_NC(rule, kind, ...) #rule,
#include "py/grammar.h"
#undef DEF_RULE
#undef DEF_RULE_NC
};
#endif
//语法规则结构定义
typedef struct _rule_stack_t {
 size_t src_line : 8 * sizeof(size_t) - 8; // 规则用在源码的行号
 size_t rule_id : 8; // 规则编号
 size_t arg_i; // 第几条规则开始,一般从0开始
} rule_stack_t;

typedef struct _mp_parse_chunk_t {
 size_t alloc; //内存块的大小
 union {
 size_t used; //内存使用了多少
 struct _mp_parse_chunk_t *next;
 } union_;
 byte data[]; //数据区
} mp_parse_chunk_t;

typedef struct _parser_t {
 size_t rule_stack_alloc; //规则分析栈,共多少项
 size_t rule_stack_top;
 rule_stack_t *rule_stack;

 size_t result_stack_alloc;//结果分析栈,共多少项
 size_t result_stack_top;
 mp_parse_node_t *result_stack; //分析树的结果节点

 mp_lexer_t *lexer; //词法分析器

 mp_parse_tree_t tree; //分析树根节点
 mp_parse_chunk_t *cur_chunk;

 #if MICROPY_COMP_CONST
 mp_map_t consts;
 #endif
} parser_t;
//获取每条规则的参数
STATIC const uint16_t *get_rule_arg(uint8_t r_id) {
 size_t off = rule_arg_offset_table[r_id];//获得参数的偏移位置
 if (r_id >= FIRST_RULE_WITH_OFFSET_ABOVE_255) {
 off |= 0x100;
 }
 return &rule_arg_combined_table[off]; //根据偏移位置得到参数首地址
}

STATIC void *parser_alloc(parser_t *parser, size_t num_bytes) {
 // use a custom memory allocator to store parse nodes sequentially in large chunks

 mp_parse_chunk_t *chunk = parser->cur_chunk;

 if (chunk != NULL && chunk->union_.used + num_bytes > chunk->alloc) {
 // not enough room at end of previously allocated chunk so try to grow
 mp_parse_chunk_t *new_data = (mp_parse_chunk_t*)m_renew_maybe(byte, chunk,
 sizeof(mp_parse_chunk_t) + chunk->alloc,
 sizeof(mp_parse_chunk_t) + chunk->alloc + num_bytes, false);
 if (new_data == NULL) {
 // could not grow existing memory; shrink it to fit previous
 (void)m_renew_maybe(byte, chunk, sizeof(mp_parse_chunk_t) + chunk->alloc,
 sizeof(mp_parse_chunk_t) + chunk->union_.used, false);
 chunk->alloc = chunk->union_.used;
 chunk->union_.next = parser->tree.chunk;
 parser->tree.chunk = chunk;
 chunk = NULL;
 } else {
 // could grow existing memory
 chunk->alloc += num_bytes;
 }
 }

 if (chunk == NULL) {
 // 没有前面分配的内存块, 分配一块新内存
 size_t alloc = MICROPY_ALLOC_PARSE_CHUNK_INIT;
 if (alloc < num_bytes) {
 alloc = num_bytes;
 }
 chunk = (mp_parse_chunk_t*)m_new(byte, sizeof(mp_parse_chunk_t) + alloc);
 chunk->alloc = alloc; //内存块的大小
 chunk->union_.used = 0; //内存没有使用
 parser->cur_chunk = chunk;
 }

 byte *ret = chunk->data + chunk->union_.used;//内存可用的开始位置
 chunk->union_.used += num_bytes;//增加已经使用空间
 return ret;
}

STATIC void push_rule(parser_t *parser, size_t src_line, uint8_t rule_id, size_t arg_i) {
 if (parser->rule_stack_top >= parser->rule_stack_alloc) {//空间不够需要分配更多空间
 rule_stack_t *rs = m_renew(rule_stack_t, parser->rule_stack, parser->rule_stack_alloc, parser->rule_stack_alloc + MICROPY_ALLOC_PARSE_RULE_INC);
 parser->rule_stack = rs;
 parser->rule_stack_alloc += MICROPY_ALLOC_PARSE_RULE_INC;
 }
 rule_stack_t *rs = &parser->rule_stack[parser->rule_stack_top++];//保存到栈里。
 rs->src_line = src_line;//当前源码行号
 rs->rule_id = rule_id; //规则编号
 rs->arg_i = arg_i;//规则开始位置
}

STATIC void push_rule_from_arg(parser_t *parser, size_t arg) {
 assert((arg & RULE_ARG_KIND_MASK) == RULE_ARG_RULE || (arg & RULE_ARG_KIND_MASK) == RULE_ARG_OPT_RULE);
 size_t rule_id = arg & RULE_ARG_ARG_MASK;
 push_rule(parser, parser->lexer->tok_line, rule_id, 0);
}
//规则出栈
STATIC uint8_t pop_rule(parser_t *parser, size_t *arg_i, size_t *src_line) {
 parser->rule_stack_top -= 1;
 uint8_t rule_id = parser->rule_stack[parser->rule_stack_top].rule_id;
 *arg_i = parser->rule_stack[parser->rule_stack_top].arg_i;
 *src_line = parser->rule_stack[parser->rule_stack_top].src_line;
 return rule_id;
}

bool mp_parse_node_is_const_false(mp_parse_node_t pn) {
 return MP_PARSE_NODE_IS_TOKEN_KIND(pn, MP_TOKEN_KW_FALSE)
 || (MP_PARSE_NODE_IS_SMALL_INT(pn) && MP_PARSE_NODE_LEAF_SMALL_INT(pn) == 0);
}

bool mp_parse_node_is_const_true(mp_parse_node_t pn) {
 return MP_PARSE_NODE_IS_TOKEN_KIND(pn, MP_TOKEN_KW_TRUE)
 || (MP_PARSE_NODE_IS_SMALL_INT(pn) && MP_PARSE_NODE_LEAF_SMALL_INT(pn) != 0);
}
//
bool mp_parse_node_get_int_maybe(mp_parse_node_t pn, mp_obj_t *o) {
 if (MP_PARSE_NODE_IS_SMALL_INT(pn)) {//如果是小型整数,取值返回
 *o = MP_OBJ_NEW_SMALL_INT(MP_PARSE_NODE_LEAF_SMALL_INT(pn));//从节点转为对象
 return true;
 } else if (MP_PARSE_NODE_IS_STRUCT_KIND(pn, RULE_const_object)) {//是否RULE_const_object对象
 mp_parse_node_struct_t *pns = (mp_parse_node_struct_t*)pn;
 #if MICROPY_OBJ_REPR == MICROPY_OBJ_REPR_D
 // nodes are 32-bit pointers, but need to extract 64-bit object
 *o = (uint64_t)pns->nodes[0] | ((uint64_t)pns->nodes[1] << 32);
 #else
 *o = (mp_obj_t)pns->nodes[0];
 #endif
 return MP_OBJ_IS_INT(*o);
 } else {//其它非常数对象类型
 return false;
 }
}

int mp_parse_node_extract_list(mp_parse_node_t *pn, size_t pn_kind, mp_parse_node_t **nodes) {
 if (MP_PARSE_NODE_IS_NULL(*pn)) {
 *nodes = NULL;
 return 0;
 } else if (MP_PARSE_NODE_IS_LEAF(*pn)) {
 *nodes = pn;
 return 1;
 } else {
 mp_parse_node_struct_t *pns = (mp_parse_node_struct_t*)(*pn);
 if (MP_PARSE_NODE_STRUCT_KIND(pns) != pn_kind) {
 *nodes = pn;
 return 1;
 } else {
 *nodes = pns->nodes;
 return MP_PARSE_NODE_STRUCT_NUM_NODES(pns);
 }
 }
}

#if MICROPY_DEBUG_PRINTERS
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;
 default:
 assert(MP_PARSE_NODE_LEAF_KIND(pn) == MP_PARSE_NODE_TOKEN);
 printf("tok(%u)\n", (uint)arg); break;
 }
 } 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_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);
 #if USE_RULE_NAME
 printf("%s(%u) (n=%u)\n", rule_name_table[MP_PARSE_NODE_STRUCT_KIND(pns)], (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);
 }
 }
 }
}
#endif // MICROPY_DEBUG_PRINTERS

/*
STATIC void result_stack_show(parser_t *parser) {
 printf("result stack, most recent first\n");
 for (ssize_t i = parser->result_stack_top - 1; i >= 0; i--) {
 mp_parse_node_print(parser->result_stack[i], 0);
 }
}
*/
//弹出栈顶元素
STATIC mp_parse_node_t pop_result(parser_t *parser) {
 assert(parser->result_stack_top > 0);
 return parser->result_stack[--parser->result_stack_top];
}
//查看栈里任意位置的元素
STATIC mp_parse_node_t peek_result(parser_t *parser, size_t pos) {
 assert(parser->result_stack_top > pos);
 return parser->result_stack[parser->result_stack_top - 1 - pos];
}
//节点压入计算分析栈顶
STATIC void push_result_node(parser_t *parser, mp_parse_node_t pn) {
 if (parser->result_stack_top >= parser->result_stack_alloc) {
 mp_parse_node_t *stack = m_renew(mp_parse_node_t, parser->result_stack, parser->result_stack_alloc, parser->result_stack_alloc + MICROPY_ALLOC_PARSE_RESULT_INC);
 parser->result_stack = stack;
 parser->result_stack_alloc += MICROPY_ALLOC_PARSE_RESULT_INC;
 }
 parser->result_stack[parser->result_stack_top++] = pn;
}
//保存一个常量节点
STATIC mp_parse_node_t make_node_const_object(parser_t *parser, size_t src_line, mp_obj_t obj) {
 mp_parse_node_struct_t *pn = parser_alloc(parser, sizeof(mp_parse_node_struct_t) + sizeof(mp_obj_t));
 pn->source_line = src_line;
 #if MICROPY_OBJ_REPR == MICROPY_OBJ_REPR_D
 // nodes are 32-bit pointers, but need to store 64-bit object
 pn->kind_num_nodes = RULE_const_object | (2 << 8);
 pn->nodes[0] = (uint64_t)obj;
 pn->nodes[1] = (uint64_t)obj >> 32;
 #else
 pn->kind_num_nodes = RULE_const_object | (1 << 8);
 pn->nodes[0] = (uintptr_t)obj;
 #endif
 return (mp_parse_node_t)pn;
}
//
STATIC mp_parse_node_t mp_parse_node_new_small_int_checked(parser_t *parser, mp_obj_t o_val) {
 (void)parser;
 mp_int_t val = MP_OBJ_SMALL_INT_VALUE(o_val);
 #if MICROPY_OBJ_REPR == MICROPY_OBJ_REPR_D
 // A parse node is only 32-bits and the small-int value must fit in 31-bits
 if (((val ^ (val << 1)) & 0xffffffff80000000) != 0) {
 return make_node_const_object(parser, 0, o_val);
 }
 #endif
 return mp_parse_node_new_small_int(val);//返回小整数节点对象
}

STATIC void push_result_token(parser_t *parser, uint8_t rule_id) {
 mp_parse_node_t pn;
 mp_lexer_t *lex = parser->lexer;
 if (lex->tok_kind == MP_TOKEN_NAME) {//标识符
 qstr id = qstr_from_strn(lex->vstr.buf, lex->vstr.len);
 #if MICROPY_COMP_CONST
 // if name is a standalone identifier, look it up in the table of dynamic constants
 mp_map_elem_t *elem;
 if (rule_id == RULE_atom
 && (elem = mp_map_lookup(&parser->consts, MP_OBJ_NEW_QSTR(id), MP_MAP_LOOKUP)) != NULL) {
 if (MP_OBJ_IS_SMALL_INT(elem->value)) {
 pn = mp_parse_node_new_small_int_checked(parser, elem->value);
 } else {
 pn = make_node_const_object(parser, lex->tok_line, elem->value);
 }
 } else {
 pn = mp_parse_node_new_leaf(MP_PARSE_NODE_ID, id);
 }
 #else
 (void)rule_id;
 pn = mp_parse_node_new_leaf(MP_PARSE_NODE_ID, id);
 #endif
 } else if (lex->tok_kind == MP_TOKEN_INTEGER) {//整数
 mp_obj_t o = mp_parse_num_integer(lex->vstr.buf, lex->vstr.len, 0, lex);
 if (MP_OBJ_IS_SMALL_INT(o)) {//小整数
 pn = mp_parse_node_new_small_int_checked(parser, o);
 } else {
 pn = make_node_const_object(parser, lex->tok_line, o);
 }
 } else if (lex->tok_kind == MP_TOKEN_FLOAT_OR_IMAG) {//浮点数或复数
 mp_obj_t o = mp_parse_num_decimal(lex->vstr.buf, lex->vstr.len, true, false, lex);
 pn = make_node_const_object(parser, lex->tok_line, o);
 } else if (lex->tok_kind == MP_TOKEN_STRING || lex->tok_kind == MP_TOKEN_BYTES) {//字符串或字节数组
 // Don't automatically intern all strings/bytes. doc strings (which are usually large)
 // will be discarded by the compiler, and so we shouldn't intern them.
 qstr qst = MP_QSTR_NULL;
 if (lex->vstr.len <= MICROPY_ALLOC_PARSE_INTERN_STRING_LEN) {
 // intern short strings
 qst = qstr_from_strn(lex->vstr.buf, lex->vstr.len);
 } else {
 // check if this string is already interned
 qst = qstr_find_strn(lex->vstr.buf, lex->vstr.len);
 }
 if (qst != MP_QSTR_NULL) {
 // qstr exists, make a leaf node
 pn = mp_parse_node_new_leaf(lex->tok_kind == MP_TOKEN_STRING ? MP_PARSE_NODE_STRING : MP_PARSE_NODE_BYTES, qst);
 } else {
 // not interned, make a node holding a pointer to the string/bytes object
 mp_obj_t o = mp_obj_new_str_copy(
 lex->tok_kind == MP_TOKEN_STRING ? &mp_type_str : &mp_type_bytes,
 (const byte*)lex->vstr.buf, lex->vstr.len);
 pn = make_node_const_object(parser, lex->tok_line, o);
 }
 } else {//其它单词,比如加号、减号...
 pn = mp_parse_node_new_leaf(MP_PARSE_NODE_TOKEN, lex->tok_kind);
 }
 push_result_node(parser, pn);//压入结果分析栈
}

#if MICROPY_COMP_MODULE_CONST
STATIC const mp_rom_map_elem_t mp_constants_table[] = {
 #if MICROPY_PY_UERRNO
 { MP_ROM_QSTR(MP_QSTR_errno), MP_ROM_PTR(&mp_module_uerrno) },
 #endif
 #if MICROPY_PY_UCTYPES
 { MP_ROM_QSTR(MP_QSTR_uctypes), MP_ROM_PTR(&mp_module_uctypes) },
 #endif
 // Extra constants as defined by a port
 MICROPY_PORT_CONSTANTS
};
STATIC MP_DEFINE_CONST_MAP(mp_constants_map, mp_constants_table);
#endif

STATIC void push_result_rule(parser_t *parser, size_t src_line, uint8_t rule_id, size_t num_args);

#if MICROPY_COMP_CONST_FOLDING
STATIC bool fold_logical_constants(parser_t *parser, uint8_t rule_id, size_t *num_args) {
 if (rule_id == RULE_or_test
 || rule_id == RULE_and_test) {
 // folding for binary logical ops: or and
 size_t copy_to = *num_args;
 for (size_t i = copy_to; i > 0;) {
 mp_parse_node_t pn = peek_result(parser, --i);
 parser->result_stack[parser->result_stack_top - copy_to] = pn;
 if (i == 0) {
 // always need to keep the last value
 break;
 }
 if (rule_id == RULE_or_test) {
 if (mp_parse_node_is_const_true(pn)) {
 //
 break;
 } else if (!mp_parse_node_is_const_false(pn)) {
 copy_to -= 1;
 }
 } else {
 // RULE_and_test
 if (mp_parse_node_is_const_false(pn)) {
 break;
 } else if (!mp_parse_node_is_const_true(pn)) {
 copy_to -= 1;
 }
 }
 }
 copy_to -= 1; // copy_to now contains number of args to pop

 // pop and discard all the short-circuited expressions
 for (size_t i = 0; i < copy_to; ++i) {
 pop_result(parser);
 }
 *num_args -= copy_to;

 // we did a complete folding if there's only 1 arg left
 return *num_args == 1;

 } else if (rule_id == RULE_not_test_2) {
 // folding for unary logical op: not
 mp_parse_node_t pn = peek_result(parser, 0);
 if (mp_parse_node_is_const_false(pn)) {
 pn = mp_parse_node_new_leaf(MP_PARSE_NODE_TOKEN, MP_TOKEN_KW_TRUE);
 } else if (mp_parse_node_is_const_true(pn)) {
 pn = mp_parse_node_new_leaf(MP_PARSE_NODE_TOKEN, MP_TOKEN_KW_FALSE);
 } else {
 return false;
 }
 pop_result(parser);
 push_result_node(parser, pn);
 return true;
 }

 return false;
}
//常量折叠,把常量计算预先计算
STATIC bool fold_constants(parser_t *parser, uint8_t rule_id, size_t num_args) {
 // 这段代码只对算术表达式进行计算, eg 1 + 2 * 3 + 4
 // 它不对部分常量进行计算, eg 1 + 2 + x -> 3 + x

 mp_obj_t arg0;
 if (rule_id == RULE_expr
 || rule_id == RULE_xor_expr
 || 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_id == RULE_expr) {
 op = MP_BINARY_OP_OR;
 } else if (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_id == RULE_shift_expr
 || rule_id == RULE_arith_expr
 || rule_id == RULE_term) {
 // 二元运算计算: << >> + - * / % //
 mp_parse_node_t pn = peek_result(parser, num_args - 1);
 if (!mp_parse_node_get_int_maybe(pn, &arg0)) {//取操作数0,非常数对象不作处理
 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)) {//取操作数1
 return false;
 }
 mp_token_kind_t tok = MP_PARSE_NODE_LEAF_ARG(peek_result(parser, i));//取操作符
 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) {//这些操作符不能提前计算
 return false;
 }
 int rhs_sign = mp_obj_int_sign(arg1);//判断符号
 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);//对二元运算进行计算
 }
 } else if (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_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, 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_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;
 }

 // 成功地折叠常量

 for (size_t i = num_args; i > 0; i--) {//清空计算栈里的参数
 pop_result(parser);
 }
 if (MP_OBJ_IS_SMALL_INT(arg0)) {//重新压入栈
 push_result_node(parser, mp_parse_node_new_small_int_checked(parser, arg0));
 } else {
 // TODO reuse memory for parse node struct?
 push_result_node(parser, make_node_const_object(parser, 0, arg0));
 }

 return true;
}
#endif

STATIC void push_result_rule(parser_t *parser, size_t src_line, uint8_t rule_id, size_t num_args) {
 // optimise away parenthesis around an expression if possible
 if (rule_id == RULE_atom_paren) {
 // there should be just 1 arg for this rule
 mp_parse_node_t pn = peek_result(parser, 0);
 if (MP_PARSE_NODE_IS_NULL(pn)) {
 // need to keep parenthesis for ()
 } else if (MP_PARSE_NODE_IS_STRUCT_KIND(pn, RULE_testlist_comp)) {
 // need to keep parenthesis for (a, b, ...)
 } else {
 // parenthesis around a single expression, so it's just the expression
 return;
 }
 }

 #if MICROPY_COMP_CONST_FOLDING
 if (fold_logical_constants(parser, rule_id, &num_args)) {
 // we folded this rule so return straight away
 return;
 }
 if (fold_constants(parser, rule_id, num_args)) {//常量折叠计算
 // we folded this rule so return straight away
 return;
 }
 #endif
	//创建一棵树
 mp_parse_node_struct_t *pn = parser_alloc(parser, sizeof(mp_parse_node_struct_t) + sizeof(mp_parse_node_t) * num_args);
 pn->source_line = src_line;
 pn->kind_num_nodes = (rule_id & 0xff) | (num_args << 8);
 for (size_t i = num_args; i > 0; i--) {
 pn->nodes[i - 1] = pop_result(parser);
 }
 push_result_node(parser, (mp_parse_node_t)pn); //树根节点压入结果分析栈
}
//分析输入的代码
mp_parse_tree_t mp_parse(mp_lexer_t *lex, mp_parse_input_kind_t input_kind) {

 // 初始化分析器和分配内存栈

 parser_t parser;
	//语法规则栈
 parser.rule_stack_alloc = MICROPY_ALLOC_PARSE_RULE_INIT;
 parser.rule_stack_top = 0;
 parser.rule_stack = m_new(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(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

 //选择使用的顶层规则, 然后把这些规则压入规则栈
 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, top_level_rule, 0); //压入分析栈

 // 开始分析

 bool backtrack = false;

 for (;;) {
 next_rule:
 if (parser.rule_stack_top == 0) {
 break;//如果没有语法规则,退出分析
 }

 // 取出下一条要处理语法规则
 size_t i; // 当前语法规则的状态
 size_t rule_src_line; // 当前规则第一个匹配单词的源码行号
 uint8_t rule_id = pop_rule(&parser, &i, &rule_src_line);//取得一条规则
 uint8_t rule_act = rule_act_table[rule_id]; //动作
 const uint16_t *rule_arg = get_rule_arg(rule_id);//获取规则的参数地址
 size_t n = rule_act & RULE_ACT_ARG_MASK;//取得本条规则有几个子句

 #if 1
 // 调试输出
 printf("depth=" UINT_FMT " ", parser.rule_stack_top);
 for (int j = 0; j < parser.rule_stack_top; ++j) {
 printf(" ");
 }
 printf("%s n=" UINT_FMT " i=" UINT_FMT " bt=%d\n", rule_name_table[rule_id], n, i, backtrack);
 #endif

 switch (rule_act & RULE_ACT_KIND_MASK) {
 case RULE_ACT_OR://语法规则为或关系
 if (i > 0 && !backtrack) {
 goto next_rule;
 } else {
 backtrack = false;
 }
				//遍历规则里每个参数
 for (; i < n; ++i) {
 uint16_t kind = rule_arg[i] & RULE_ARG_KIND_MASK;//规则里参数类型
 if (kind == RULE_ARG_TOK) {//判断是否终结符
 if (lex->tok_kind == (rule_arg[i] & RULE_ARG_ARG_MASK)) {
 push_result_token(&parser, rule_id);
 mp_lexer_to_next(lex);
 goto next_rule;
 }
 } else {//下一条规则
 assert(kind == RULE_ARG_RULE);
 if (i + 1 < n) {
 push_rule(&parser, rule_src_line, rule_id, i + 1); // 保存下一个或规则到分析栈
 }
 push_rule_from_arg(&parser, rule_arg[i]); // 保存当前规则的子或规则到分析栈
 goto next_rule;//跳到分析子规则(深度优先原则)
 }
 }
 backtrack = true;//要回朔前一个规则
 break;

 case RULE_ACT_AND: {//语法规则为与关系

 // 如果是回朔,判断是否可以, 否则表示语法出错
 if (backtrack) {
 assert(i > 0);
 if ((rule_arg[i - 1] & RULE_ARG_KIND_MASK) == RULE_ARG_OPT_RULE) {
 // 如果是可选的参数失败,继续下一个参数
 push_result_node(&parser, MP_PARSE_NODE_NULL);
 backtrack = false;
 } else {
 // a mandatory rule that failed, so propagate backtrack
 if (i > 1) {
 // 退回不了,语法出错。
 goto syntax_error;
 } else {
 goto next_rule;
 }
 }
 }

 // 遍历所有规则
 for (; i < n; ++i) {
 if ((rule_arg[i] & RULE_ARG_KIND_MASK) == RULE_ARG_TOK) {
 // 需要匹配一个token
 mp_token_kind_t tok_kind = rule_arg[i] & RULE_ARG_ARG_MASK;
 if (lex->tok_kind == tok_kind) {
 //当前的token与规则要求的一致
 if (tok_kind == MP_TOKEN_NAME) {
 push_result_token(&parser, rule_id);//标识符压入结果栈
 }
 mp_lexer_to_next(lex);
 } else {
 // 匹配token失败
 if (i > 0) {
 // 已经分析过了,不能回退。
 goto syntax_error;
 } else {
 // 这个规则分析失败,回退
 backtrack = true;
 goto next_rule;
 }
 }
 } else {
 push_rule(&parser, rule_src_line, rule_id, i + 1); // 保存下一个and-rule
 push_rule_from_arg(&parser, rule_arg[i]); // 保存当前and-rule的子规则进入处理
 goto next_rule;
 }
 }

 assert(i == n);

 // 符合语法规则,创建分析节点

 #if !MICROPY_ENABLE_DOC_STRING
 // 这段代码用来丢掉可以不用的代码, 比如文档说明字符串。
 if (input_kind != MP_PARSE_SINGLE_INPUT && 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_const_object)) {
 pop_result(&parser); // MP_PARSE_NODE_NULL
 pop_result(&parser); // const expression (leaf or RULE_const_object)
 // Pushing the "pass" rule here will overwrite any RULE_const_object
 // entry that was on the result stack, allowing the GC to reclaim
 // the memory from the const object when needed.
 push_result_rule(&parser, rule_src_line, 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_id, i);
 }
 break;
 }

 default: {//语法规则为并列关系
 assert((rule_act & RULE_ACT_KIND_MASK) == RULE_ACT_LIST);

 // n=2 is: item item*
 // n=1 is: item (sep item)*
 // n=3 is: item (sep item)* [sep]
 bool had_trailing_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 (;;) {
 size_t arg = rule_arg[i & 1 & n];
 if ((arg & RULE_ARG_KIND_MASK) == RULE_ARG_TOK) {
 if (lex->tok_kind == (arg & RULE_ARG_ARG_MASK)) {
 if (i & 1 & n) {
 // separators which are tokens are not pushed to result stack
 } else {
 push_result_token(&parser, rule_id);
 }
 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;
 }
 } else {
 assert((arg & RULE_ARG_KIND_MASK) == RULE_ARG_RULE);
 push_rule(&parser, rule_src_line, rule_id, i + 1); // save this list-rule
 push_rule_from_arg(&parser, arg); // push child of list-rule
 goto next_rule;
 }
 }
 }
 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_id, i);
 } else {
 // just leave single item on stack (ie don't wrap in a list)
 }
 } else {
 push_result_rule(&parser, rule_src_line, rule_id, i);
 }
 break;
 }
 }
 }

 #if MICROPY_COMP_CONST
 mp_map_deinit(&parser.consts);
 #endif

 // truncate final chunk and link into chain of chunks
 if (parser.cur_chunk != NULL) {
 (void)m_renew_maybe(byte, parser.cur_chunk,
 sizeof(mp_parse_chunk_t) + parser.cur_chunk->alloc,
 sizeof(mp_parse_chunk_t) + parser.cur_chunk->union_.used,
 false);
 parser.cur_chunk->alloc = parser.cur_chunk->union_.used;
 parser.cur_chunk->union_.next = parser.tree.chunk;
 parser.tree.chunk = parser.cur_chunk;
 }

 if (
 lex->tok_kind != MP_TOKEN_END // 分析完成,输入流还没有数据,表示已经出错。
 || parser.result_stack_top == 0 // 结果栈为空
 ) {
 syntax_error:; //语法出错处理
 mp_obj_t exc;
 if (lex->tok_kind == MP_TOKEN_INDENT) {//不应该缩进语法出错
 exc = mp_obj_new_exception_msg(&mp_type_IndentationError,
 "unexpected indent");
 } else if (lex->tok_kind == MP_TOKEN_DEDENT_MISMATCH) {//格式不对齐出错
 exc = mp_obj_new_exception_msg(&mp_type_IndentationError,
 "unindent does not match any outer indentation level");
 } else {//非法的语法错误
 exc = mp_obj_new_exception_msg(&mp_type_SyntaxError,
 "invalid syntax");
 }
 // 在traceback显示里添加源码文件名称和行号显示
 // we don't have a 'block' name, so just pass the NULL qstr to indicate this
 mp_obj_exception_add_traceback(exc, lex->source_name, lex->tok_line, MP_QSTR_NULL);
 nlr_raise(exc);
 }

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

 // 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);

 // we also free the lexer on behalf of the caller
 mp_lexer_free(lex);

 return parser.tree;
}

void mp_parse_tree_clear(mp_parse_tree_t *tree) {
 mp_parse_chunk_t *chunk = tree->chunk;
 while (chunk != NULL) {
 mp_parse_chunk_t *next = chunk->union_.next;
 m_del(byte, chunk, sizeof(mp_parse_chunk_t) + chunk->alloc);
 chunk = next;
 }
}

#endif // MICROPY_ENABLE_COMPILER