/*
 * This file is part of the MicroPython project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2013, 2014 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 <stdio.h>
#include <string.h>
#include <assert.h>

#include "py/reader.h"
#include "py/lexer.h"
#include "py/runtime.h"

#if MICROPY_ENABLE_COMPILER

#define TAB_SIZE (8)

// TODO seems that CPython allows NULL byte in the input stream
// don't know if that's intentional or not, but we don't allow it

#define MP_LEXER_EOF ((unichar)MP_READER_EOF)
#define CUR_CHAR(lex) ((lex)->chr0)

STATIC bool is_end(mp_lexer_t *lex) {
 return lex->chr0 == MP_LEXER_EOF;
}

STATIC bool is_physical_newline(mp_lexer_t *lex) {
 return lex->chr0 == '\n';
}

STATIC bool is_char(mp_lexer_t *lex, byte c) {
 return lex->chr0 == c;
}

STATIC bool is_char_or(mp_lexer_t *lex, byte c1, byte c2) {
 return lex->chr0 == c1 || lex->chr0 == c2;
}

STATIC bool is_char_or3(mp_lexer_t *lex, byte c1, byte c2, byte c3) {
 return lex->chr0 == c1 || lex->chr0 == c2 || lex->chr0 == c3;
}

STATIC bool is_char_following(mp_lexer_t *lex, byte c) {
 return lex->chr1 == c;
}

STATIC bool is_char_following_or(mp_lexer_t *lex, byte c1, byte c2) {
 return lex->chr1 == c1 || lex->chr1 == c2;
}

STATIC bool is_char_following_following_or(mp_lexer_t *lex, byte c1, byte c2) {
 return lex->chr2 == c1 || lex->chr2 == c2;
}

STATIC bool is_char_and(mp_lexer_t *lex, byte c1, byte c2) {
 return lex->chr0 == c1 && lex->chr1 == c2;
}

STATIC bool is_whitespace(mp_lexer_t *lex) {
 return unichar_isspace(lex->chr0);
}

STATIC bool is_letter(mp_lexer_t *lex) {
 return unichar_isalpha(lex->chr0);
}

STATIC bool is_digit(mp_lexer_t *lex) {
 return unichar_isdigit(lex->chr0);
}

STATIC bool is_following_digit(mp_lexer_t *lex) {
 return unichar_isdigit(lex->chr1);
}

STATIC bool is_following_base_char(mp_lexer_t *lex) {
 const unichar chr1 = lex->chr1 | 0x20;
 return chr1 == 'b' || chr1 == 'o' || chr1 == 'x';
}

STATIC bool is_following_odigit(mp_lexer_t *lex) {
 return lex->chr1 >= '0' && lex->chr1 <= '7';
}

STATIC bool is_string_or_bytes(mp_lexer_t *lex) {
 return is_char_or(lex, '\'', '\"')
 || (is_char_or3(lex, 'r', 'u', 'b') && is_char_following_or(lex, '\'', '\"'))
 || ((is_char_and(lex, 'r', 'b') || is_char_and(lex, 'b', 'r'))
 && is_char_following_following_or(lex, '\'', '\"'));
}

// to easily parse utf-8 identifiers we allow any raw byte with high bit set
STATIC bool is_head_of_identifier(mp_lexer_t *lex) {
 return is_letter(lex) || lex->chr0 == '_' || lex->chr0 >= 0x80;
}

STATIC bool is_tail_of_identifier(mp_lexer_t *lex) {
 return is_head_of_identifier(lex) || is_digit(lex);
}

STATIC void next_char(mp_lexer_t *lex) {
 if (lex->chr0 == '\n') {
 // a new line
 ++lex->line;
 lex->column = 1;
 } else if (lex->chr0 == '\t') {
 // a tab
 lex->column = (((lex->column - 1 + TAB_SIZE) / TAB_SIZE) * TAB_SIZE) + 1;
 } else {
 // a character worth one column
 ++lex->column;
 }

 lex->chr0 = lex->chr1;
 lex->chr1 = lex->chr2;
 lex->chr2 = lex->reader.readbyte(lex->reader.data);

 if (lex->chr1 == '\r') {
 // CR is a new line, converted to LF
 lex->chr1 = '\n';
 if (lex->chr2 == '\n') {
 // CR LF is a single new line, throw out the extra LF
 lex->chr2 = lex->reader.readbyte(lex->reader.data);
 }
 }

 // check if we need to insert a newline at end of file
 if (lex->chr2 == MP_LEXER_EOF && lex->chr1 != MP_LEXER_EOF && lex->chr1 != '\n') {
 lex->chr2 = '\n';
 }
}
//缩进代码块入栈
STATIC void indent_push(mp_lexer_t *lex, size_t indent) {
 if (lex->num_indent_level >= lex->alloc_indent_level) {
 lex->indent_level = m_renew(uint16_t, lex->indent_level, lex->alloc_indent_level, lex->alloc_indent_level + MICROPY_ALLOC_LEXEL_INDENT_INC);
 lex->alloc_indent_level += MICROPY_ALLOC_LEXEL_INDENT_INC;
 }
 lex->indent_level[lex->num_indent_level++] = indent;
}
//缩进代码块栈顶取回
STATIC size_t indent_top(mp_lexer_t *lex) {
 return lex->indent_level[lex->num_indent_level - 1];
}
//缩进代码块出栈
STATIC void indent_pop(mp_lexer_t *lex) {
 lex->num_indent_level -= 1;
}

// some tricky operator encoding:
// <op> = begin with <op>, if this opchar matches then begin here
// e<op> = end with <op>, if this opchar matches then end
// c<op> = continue with <op>, if this opchar matches then continue matching
// this means if the start of two ops are the same then they are equal til the last char

STATIC const char *const tok_enc =
 "()[]{},:;@~" // singles
 "<e=c<e=" // < <= << <<=
 ">e=c>e=" // > >= >> >>=
 "*e=c*e=" // * *= ** **=
 "+e=" // + +=
 "-e=e>" // - -= ->
 "&e=" // & &=
 "|e=" // | |=
 "/e=c/e=" // / /= // //=
 "%e=" // % %=
 "^e=" // ^ ^=
 "=e=" // = ==
 "!."; // start of special cases: != . ...

// TODO static assert that number of tokens is less than 256 so we can safely make this table with byte sized entries
STATIC const uint8_t tok_enc_kind[] = {
 MP_TOKEN_DEL_PAREN_OPEN, MP_TOKEN_DEL_PAREN_CLOSE,
 MP_TOKEN_DEL_BRACKET_OPEN, MP_TOKEN_DEL_BRACKET_CLOSE,
 MP_TOKEN_DEL_BRACE_OPEN, MP_TOKEN_DEL_BRACE_CLOSE,
 MP_TOKEN_DEL_COMMA, MP_TOKEN_DEL_COLON, MP_TOKEN_DEL_SEMICOLON, MP_TOKEN_DEL_AT, MP_TOKEN_OP_TILDE,

 MP_TOKEN_OP_LESS, MP_TOKEN_OP_LESS_EQUAL, MP_TOKEN_OP_DBL_LESS, MP_TOKEN_DEL_DBL_LESS_EQUAL,
 MP_TOKEN_OP_MORE, MP_TOKEN_OP_MORE_EQUAL, MP_TOKEN_OP_DBL_MORE, MP_TOKEN_DEL_DBL_MORE_EQUAL,
 MP_TOKEN_OP_STAR, MP_TOKEN_DEL_STAR_EQUAL, MP_TOKEN_OP_DBL_STAR, MP_TOKEN_DEL_DBL_STAR_EQUAL,
 MP_TOKEN_OP_PLUS, MP_TOKEN_DEL_PLUS_EQUAL,
 MP_TOKEN_OP_MINUS, MP_TOKEN_DEL_MINUS_EQUAL, MP_TOKEN_DEL_MINUS_MORE,
 MP_TOKEN_OP_AMPERSAND, MP_TOKEN_DEL_AMPERSAND_EQUAL,
 MP_TOKEN_OP_PIPE, MP_TOKEN_DEL_PIPE_EQUAL,
 MP_TOKEN_OP_SLASH, MP_TOKEN_DEL_SLASH_EQUAL, MP_TOKEN_OP_DBL_SLASH, MP_TOKEN_DEL_DBL_SLASH_EQUAL,
 MP_TOKEN_OP_PERCENT, MP_TOKEN_DEL_PERCENT_EQUAL,
 MP_TOKEN_OP_CARET, MP_TOKEN_DEL_CARET_EQUAL,
 MP_TOKEN_DEL_EQUAL, MP_TOKEN_OP_DBL_EQUAL,
};

// must have the same order as enum in lexer.h
// 必须按ASCII表来排序,满足strcmp函数返回大于0的值
STATIC const char *const tok_kw[] = {
 "False",
 "None",
 "True",
 "__debug__",
 "and",
 "as",
 "assert",
 #if MICROPY_PY_ASYNC_AWAIT
 "async",
 "await",
 #endif
 "break",
 "class",
 "continue",
 "def",
 "del",
 "elif",
 "else",
 "except",
 "finally",
 "for",
 "from",
 "global",
 "if",
 "import",
 "in",
 "is",
 "lambda",
 "nonlocal",
 "not",
 "or",
 "pass",
 "raise",
 "return",
 "try",
 "while",
 "with",
 "yield",
};

// This is called with CUR_CHAR() before first hex digit, and should return with
// it pointing to last hex digit
// num_digits must be greater than zero
STATIC bool get_hex(mp_lexer_t *lex, size_t num_digits, mp_uint_t *result) {
 mp_uint_t num = 0;
 while (num_digits-- != 0) {
 next_char(lex);
 unichar c = CUR_CHAR(lex);
 if (!unichar_isxdigit(c)) {
 return false;
 }
 num = (num << 4) + unichar_xdigit_value(c);
 }
 *result = num;
 return true;
}

STATIC void parse_string_literal(mp_lexer_t *lex, bool is_raw) {
 // get first quoting character
 char quote_char = '\'';
 if (is_char(lex, '\"')) {
 quote_char = '\"';
 }
 next_char(lex);

 // work out if it's a single or triple quoted literal
 size_t num_quotes;
 if (is_char_and(lex, quote_char, quote_char)) {
 // triple quotes
 next_char(lex);
 next_char(lex);
 num_quotes = 3;
 } else {
 // single quotes
 num_quotes = 1;
 }

 size_t n_closing = 0;
 while (!is_end(lex) && (num_quotes > 1 || !is_char(lex, '\n')) && n_closing < num_quotes) {
 if (is_char(lex, quote_char)) {
 n_closing += 1;
 vstr_add_char(&lex->vstr, CUR_CHAR(lex));
 } else {
 n_closing = 0;
 if (is_char(lex, '\\')) {
 next_char(lex);
 unichar c = CUR_CHAR(lex);
 if (is_raw) {
 // raw strings allow escaping of quotes, but the backslash is also emitted
 vstr_add_char(&lex->vstr, '\\');
 } else {
 switch (c) {
 // note: "c" can never be MP_LEXER_EOF because next_char
 // always inserts a newline at the end of the input stream
 case '\n': c = MP_LEXER_EOF; break; // backslash escape the newline, just ignore it
 case '\\': break;
 case '\'': break;
 case '"': break;
 case 'a': c = 0x07; break;
 case 'b': c = 0x08; break;
 case 't': c = 0x09; break;
 case 'n': c = 0x0a; break;
 case 'v': c = 0x0b; break;
 case 'f': c = 0x0c; break;
 case 'r': c = 0x0d; break;
 case 'u':
 case 'U':
 if (lex->tok_kind == MP_TOKEN_BYTES) {
 // b'\u1234' == b'\\u1234'
 vstr_add_char(&lex->vstr, '\\');
 break;
 }
 // Otherwise fall through.
 case 'x':
 {
 mp_uint_t num = 0;
 if (!get_hex(lex, (c == 'x' ? 2 : c == 'u' ? 4 : 8), &num)) {
 // not enough hex chars for escape sequence
 lex->tok_kind = MP_TOKEN_INVALID;
 }
 c = num;
 break;
 }
 case 'N':
 // Supporting '\N{LATIN SMALL LETTER A}' == 'a' would require keeping the
 // entire Unicode name table in the core. As of Unicode 6.3.0, that's nearly
 // 3MB of text; even gzip-compressed and with minimal structure, it'll take
 // roughly half a meg of storage. This form of Unicode escape may be added
 // later on, but it's definitely not a priority right now. -- CJA 20140607
 mp_raise_NotImplementedError("unicode name escapes");
 break;
 default:
 if (c >= '0' && c <= '7') {
 // Octal sequence, 1-3 chars
 size_t digits = 3;
 mp_uint_t num = c - '0';
 while (is_following_odigit(lex) && --digits != 0) {
 next_char(lex);
 num = num * 8 + (CUR_CHAR(lex) - '0');
 }
 c = num;
 } else {
 // unrecognised escape character; CPython lets this through verbatim as '\' and then the character
 vstr_add_char(&lex->vstr, '\\');
 }
 break;
 }
 }
 if (c != MP_LEXER_EOF) {
 if (MICROPY_PY_BUILTINS_STR_UNICODE_DYNAMIC) {
 if (c < 0x110000 && lex->tok_kind == MP_TOKEN_STRING) {
 vstr_add_char(&lex->vstr, c);
 } else if (c < 0x100 && lex->tok_kind == MP_TOKEN_BYTES) {
 vstr_add_byte(&lex->vstr, c);
 } else {
 // unicode character out of range
 // this raises a generic SyntaxError; could provide more info
 lex->tok_kind = MP_TOKEN_INVALID;
 }
 } else {
 // without unicode everything is just added as an 8-bit byte
 if (c < 0x100) {
 vstr_add_byte(&lex->vstr, c);
 } else {
 // 8-bit character out of range
 // this raises a generic SyntaxError; could provide more info
 lex->tok_kind = MP_TOKEN_INVALID;
 }
 }
 }
 } else {
 // Add the "character" as a byte so that we remain 8-bit clean.
 // This way, strings are parsed correctly whether or not they contain utf-8 chars.
 vstr_add_byte(&lex->vstr, CUR_CHAR(lex));
 }
 }
 next_char(lex);
 }

 // check we got the required end quotes
 if (n_closing < num_quotes) {
 lex->tok_kind = MP_TOKEN_LONELY_STRING_OPEN;
 }

 // cut off the end quotes from the token text
 vstr_cut_tail_bytes(&lex->vstr, n_closing);
}

STATIC bool skip_whitespace(mp_lexer_t *lex, bool stop_at_newline) {
 bool had_physical_newline = false;
 while (!is_end(lex)) {
 if (is_physical_newline(lex)) {
 if (stop_at_newline && lex->nested_bracket_level == 0) {
 break;
 }
 had_physical_newline = true;
 next_char(lex);
 } else if (is_whitespace(lex)) {
 next_char(lex);
 } else if (is_char(lex, '#')) {
 next_char(lex);
 while (!is_end(lex) && !is_physical_newline(lex)) {
 next_char(lex);
 }
 // had_physical_newline will be set on next loop
 } else if (is_char_and(lex, '\\', '\n')) {
 // line-continuation, so don't set had_physical_newline
 next_char(lex);
 next_char(lex);
 } else {
 break;
 }
 }
 return had_physical_newline;
}
//词法分析
void mp_lexer_to_next(mp_lexer_t *lex) {
 // start new token text
 vstr_reset(&lex->vstr);

 // 跳过空格和注释
 bool had_physical_newline = skip_whitespace(lex, false);

 // 设置 token在源程序里的位置信息
 lex->tok_line = lex->line;
 lex->tok_column = lex->column;

 if (lex->emit_dent < 0) {
 lex->tok_kind = MP_TOKEN_DEDENT; //退出缩进代码块
 lex->emit_dent += 1;

 } else if (lex->emit_dent > 0) {
 lex->tok_kind = MP_TOKEN_INDENT; //缩进代码块
 lex->emit_dent -= 1;

 } else if (had_physical_newline && lex->nested_bracket_level == 0) {
 lex->tok_kind = MP_TOKEN_NEWLINE; //新行

 size_t num_spaces = lex->column - 1;
 if (num_spaces == indent_top(lex)) {
 } else if (num_spaces > indent_top(lex)) {
 indent_push(lex, num_spaces);
 lex->emit_dent += 1; //新的代码块开始
 } else {
 while (num_spaces < indent_top(lex)) {
 indent_pop(lex);
 lex->emit_dent -= 1; //退出缩进代码块
 }
 if (num_spaces != indent_top(lex)) {
 lex->tok_kind = MP_TOKEN_DEDENT_MISMATCH;
 }
 }

 } else if (is_end(lex)) {
 lex->tok_kind = MP_TOKEN_END;//源码分析完成

 } else if (is_string_or_bytes(lex)) {
 // 是一个字符串或字节数组

 // Python requires adjacent string/bytes literals to be automatically
 // concatenated. We do it here in the tokeniser to make efficient use of RAM,
 // because then the lexer's vstr can be used to accumulate the string literal,
 // in contrast to creating a parse tree of strings and then joining them later
 // in the compiler. It's also more compact in code size to do it here.

 // MP_TOKEN_END is used to indicate that this is the first string token
 lex->tok_kind = MP_TOKEN_END;

 // Loop to accumulate string/bytes literals
 do {
 // parse type codes
 bool is_raw = false;
 mp_token_kind_t kind = MP_TOKEN_STRING;
 int n_char = 0;
 if (is_char(lex, 'u')) {
 n_char = 1;
 } else if (is_char(lex, 'b')) {
 kind = MP_TOKEN_BYTES;
 n_char = 1;
 if (is_char_following(lex, 'r')) {
 is_raw = true;
 n_char = 2;
 }
 } else if (is_char(lex, 'r')) {
 is_raw = true;
 n_char = 1;
 if (is_char_following(lex, 'b')) {
 kind = MP_TOKEN_BYTES;
 n_char = 2;
 }
 }

 // Set or check token kind
 if (lex->tok_kind == MP_TOKEN_END) {
 lex->tok_kind = kind;
 } else if (lex->tok_kind != kind) {
 // Can't concatenate string with bytes
 break;
 }

 // Skip any type code characters
 if (n_char != 0) {
 next_char(lex);
 if (n_char == 2) {
 next_char(lex);
 }
 }

 // Parse the literal
 parse_string_literal(lex, is_raw);

 // Skip whitespace so we can check if there's another string following
 skip_whitespace(lex, true);

 } while (is_string_or_bytes(lex));

 } else if (is_head_of_identifier(lex)) {
 lex->tok_kind = MP_TOKEN_NAME;//标识符

 // get first char (add as byte to remain 8-bit clean and support utf-8)
 vstr_add_byte(&lex->vstr, CUR_CHAR(lex));
 next_char(lex);

 // get tail chars
 while (!is_end(lex) && is_tail_of_identifier(lex)) {
 vstr_add_byte(&lex->vstr, CUR_CHAR(lex));
 next_char(lex);
 }

 // 检查标识符是否关键字keyword.
 // We also check for __debug__ here and convert it to its value. This is
 // so the parser gives a syntax error on, eg, x.__debug__. Otherwise, we
 // need to check for this special token in many places in the compiler.
 const char *s = vstr_null_terminated_str(&lex->vstr);
 for (size_t i = 0; i < MP_ARRAY_SIZE(tok_kw); i++) {
 int cmp = strcmp(s, tok_kw[i]);//关键字比较
 if (cmp == 0) {
 lex->tok_kind = MP_TOKEN_KW_FALSE + i;
 if (lex->tok_kind == MP_TOKEN_KW___DEBUG__) {
 lex->tok_kind = (MP_STATE_VM(mp_optimise_value) == 0 ? MP_TOKEN_KW_TRUE : MP_TOKEN_KW_FALSE);
 }
 break;
 } else if (cmp < 0) {
 //由于关键字表已经排过序,如果小于说明不存此关键字。跳出搜索
 break;
 }
 }

 } else if (is_digit(lex) || (is_char(lex, '.') && is_following_digit(lex))) {
		//数字串识别
 bool forced_integer = false;
 if (is_char(lex, '.')) {
 lex->tok_kind = MP_TOKEN_FLOAT_OR_IMAG;
 } else {
 lex->tok_kind = MP_TOKEN_INTEGER;
 if (is_char(lex, '0') && is_following_base_char(lex)) {
 forced_integer = true;
 }
 }

 // get first char
 vstr_add_char(&lex->vstr, CUR_CHAR(lex));
 next_char(lex);

 // get tail chars
 while (!is_end(lex)) {
 if (!forced_integer && is_char_or(lex, 'e', 'E')) {
 lex->tok_kind = MP_TOKEN_FLOAT_OR_IMAG;
 vstr_add_char(&lex->vstr, 'e');
 next_char(lex);
 if (is_char(lex, '+') || is_char(lex, '-')) {
 vstr_add_char(&lex->vstr, CUR_CHAR(lex));
 next_char(lex);
 }
 } else if (is_letter(lex) || is_digit(lex) || is_char(lex, '.')) {
 if (is_char_or3(lex, '.', 'j', 'J')) {
 lex->tok_kind = MP_TOKEN_FLOAT_OR_IMAG;
 }
 vstr_add_char(&lex->vstr, CUR_CHAR(lex));
 next_char(lex);
 } else {
 break;
 }
 }

 } else {
 // 搜索像括号这样的分界符或操作符

 const char *t = tok_enc;
 size_t tok_enc_index = 0;
 for (; *t != 0 && !is_char(lex, *t); t += 1) {
 if (*t == 'e' || *t == 'c') {
 t += 1;
 }
 tok_enc_index += 1;
 }

 next_char(lex);

 if (*t == 0) {
 // didn't match any delimiter or operator characters
 lex->tok_kind = MP_TOKEN_INVALID;

 } else if (*t == '!') {
 // "!=" is a special case because "!" is not a valid operator
 if (is_char(lex, '=')) {
 next_char(lex);
 lex->tok_kind = MP_TOKEN_OP_NOT_EQUAL;
 } else {
 lex->tok_kind = MP_TOKEN_INVALID;
 }

 } else if (*t == '.') {
 // "." and "..." are special cases because ".." is not a valid operator
 if (is_char_and(lex, '.', '.')) {
 next_char(lex);
 next_char(lex);
 lex->tok_kind = MP_TOKEN_ELLIPSIS;
 } else {
 lex->tok_kind = MP_TOKEN_DEL_PERIOD;
 }

 } else {
 // matched a delimiter or operator character

 // get the maximum characters for a valid token
 t += 1;
 size_t t_index = tok_enc_index;
 while (*t == 'c' || *t == 'e') {
 t_index += 1;
 if (is_char(lex, t[1])) {
 next_char(lex);
 tok_enc_index = t_index;
 if (*t == 'e') {
 break;
 }
 } else if (*t == 'c') {
 break;
 }
 t += 2;
 }

 // set token kind
 lex->tok_kind = tok_enc_kind[tok_enc_index];

 // compute bracket level for implicit line joining
 if (lex->tok_kind == MP_TOKEN_DEL_PAREN_OPEN || lex->tok_kind == MP_TOKEN_DEL_BRACKET_OPEN || lex->tok_kind == MP_TOKEN_DEL_BRACE_OPEN) {
 lex->nested_bracket_level += 1;
 } else if (lex->tok_kind == MP_TOKEN_DEL_PAREN_CLOSE || lex->tok_kind == MP_TOKEN_DEL_BRACKET_CLOSE || lex->tok_kind == MP_TOKEN_DEL_BRACE_CLOSE) {
 lex->nested_bracket_level -= 1;
 }
 }
 }
}

mp_lexer_t *mp_lexer_new(qstr src_name, mp_reader_t reader) {
 mp_lexer_t *lex = m_new_obj(mp_lexer_t);//创建词法分析对象

 lex->source_name = src_name;
 lex->reader = reader; //
 lex->line = 1;
 lex->column = (size_t)-2; // 有三个提示符字节
 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(uint16_t, lex->alloc_indent_level);
 vstr_init(&lex->vstr, 32);

 // 设置0级缩进为0.
 lex->indent_level[0] = 0;

 // 从文件开头加载三个字符到缓冲区, 然后把行号lex->column移到1
 // start with dummy bytes and use next_char() for proper EOL/EOF handling
 lex->chr0 = lex->chr1 = lex->chr2 = 0;
 next_char(lex);
 next_char(lex);
 next_char(lex);

 // 获得第一个单词类型
 mp_lexer_to_next(lex);

 // 检查第一个单词不在第一列上,标志为非法缩进,以便语法分析出错,报告错误位置。
 if (lex->tok_column != 1) {
 lex->tok_kind = MP_TOKEN_INDENT;
 }

 return lex;
}

mp_lexer_t *mp_lexer_new_from_str_len(qstr src_name, const char *str, size_t len, size_t free_len) {
 //把字符串放到内存对象里。
	mp_reader_t reader;
 mp_reader_new_mem(&reader, (const byte*)str, len, free_len);

 return mp_lexer_new(src_name, reader);
}

#if MICROPY_READER_POSIX || MICROPY_READER_VFS

mp_lexer_t *mp_lexer_new_from_file(const char *filename) {
 mp_reader_t reader;
 mp_reader_new_file(&reader, filename);
 return mp_lexer_new(qstr_from_str(filename), reader);
}

#if MICROPY_HELPER_LEXER_UNIX

mp_lexer_t *mp_lexer_new_from_fd(qstr filename, int fd, bool close_fd) {
 mp_reader_t reader;
 mp_reader_new_file_from_fd(&reader, fd, close_fd);
 return mp_lexer_new(filename, reader);
}

#endif

#endif

void mp_lexer_free(mp_lexer_t *lex) {
 if (lex) {
 lex->reader.close(lex->reader.data);
 vstr_clear(&lex->vstr);
 m_del(uint16_t, lex->indent_level, lex->alloc_indent_level);
 m_del_obj(mp_lexer_t, lex);
 }
}

#if 0
// This function is used to print the current token and should only be
// needed to debug the lexer, so it's not available via a config option.
void mp_lexer_show_token(const mp_lexer_t *lex) {
 printf("(" UINT_FMT ":" UINT_FMT ") kind:%u str:%p len:%zu", lex->tok_line, lex->tok_column, lex->tok_kind, lex->vstr.buf, lex->vstr.len);
 if (lex->vstr.len > 0) {
 const byte *i = (const byte *)lex->vstr.buf;
 const byte *j = (const byte *)i + lex->vstr.len;
 printf(" ");
 while (i < j) {
 unichar c = utf8_get_char(i);
 i = utf8_next_char(i);
 if (unichar_isprint(c)) {
 printf("%c", (int)c);
 } else {
 printf("?");
 }
 }
 }
 printf("\n");
}
#endif

#endif // MICROPY_ENABLE_COMPILER