我正在收拾我的词法分析器，但我在打印和正确分配数字时遇到问题。以下是我的输出，应为lexer_num，我认为问题出现在lexer_flt或v附近：
（包括所要求的更多信息。）我没有或者真的知道十六进制转储是什么，所以我认为我不能提供。要回答关于lexer_num Type: "40" {
Line: "1"
Pos: "0"
Num: "2591542"
Real: "0.000000"
Stri: ""
}
中#define _CRT_SECURE_NO_WARNINGS
#define DEBUG 0
#include "lexer.h"
#include "error.h"
#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#include <ctype.h>
#include <assert.h>
typedef struct lextoken_t {
const char* str;
token_t type;
} lextoken_t;
static const lextoken_t keywords[] = {
// types
{ "int", _int },
{ "double", _dbl },
{ "void", _void },
{ "char", _char },
{ "string", _str },
{ "bool", _bool },
{ "const", _const },
{ "struct", _struct }
};
/* token_new: creates and returns a new token ptr.
** -lexer: a ptr to the lexer.
** -type: the token type.
*/
token_t* token_new(lexer_t* lexer, tk_type type) {
token_t* token = malloc(sizeof(token_t));
token->line = lexer->line;
token->pos = lexer->pos;
token->type = type;
token->integer = 0;
token->flt = 0;
token->string = NULL;
return token;
}
static void token_print(token_t* token) {
if (token == NULL)
printf("Null token");
printf("Type: \"%i\" { \n", token->type);
printf("\tLine: \"%i\"\n", token->line);
printf("\tPos: \"%i\"\n", token->pos);
printf("\tNum: \"%i\"\n", token->integer);
printf("\tReal: \"%f\"\n", token->flt);
printf("\tStri: \"%s\"\n}\n\n", token->string);
}
/* lexer_look: look at the source (ahead) places infront of the lexer->ptr.
** -lexer: a ptr to the lexer to look ahead in.
** -ahead: how far ahead of the ptr to look.
*/
static char lexer_look(lexer_t* lexer, size_t ahead) {
if (lexer->len < lexer->ptr + ahead) {
error_new(lexer->errors, 0, 0, "The lexer tried to index %d out of bounds %d", lexer->ptr + ahead, lexer->len);
return;
}
return lexer->src[lexer->ptr + ahead];
}
static size_t can_adv(lexer_t* lexer, size_t steps) {
if (lexer->ptr + steps <= lexer->len)
return 1;
else
return 0;
}
/* lexer_adv: moves the lexer->ptr (steps) places.
** -lexer: a ptr to the lexer to look ahead in.
** -steps: how far to advance the ptr.
*/
static char lexer_adv(lexer_t* lexer, size_t steps) {
if (!can_adv(lexer, steps))
error_new(lexer->errors, 0, 0, "The lexer tried to move ptr past bounds %d with value of %d", lexer->len, lexer->ptr + steps);
lexer->ptr += steps;
return lexer->src[lexer->ptr];
}
static void new_line(lexer_t* lexer) {
lexer->line = 0;
lexer->pos = 0;
}
static void lexer_nested(lexer_t* lexer) {
lexer_adv(lexer, 2);
char c = lexer_look(lexer, 0);
size_t depth = 1;
while (depth > 0) {
if (!can_adv(lexer, 1))
error_new(lexer->errors, lexer->line, lexer->pos, "Unterminated block comment.");
else if (c == '*' && lexer_look(lexer, 1) == '#') {
lexer_adv(lexer, 2);
depth--;
} else if (c == '#' && lexer_look(lexer, 1) == '*') {
lexer_adv(lexer, 2);
depth++;
} else
c = lexer_adv(lexer, 1);
}
}
static void lexer_comment(lexer_t* lexer) {
if (lexer_look(lexer, 1) == '*')
lexer_nested(lexer);
else {
char c;
while (((c = lexer_look(lexer, 0)) != '\n') && can_adv(lexer, 1))
lexer_adv(lexer, 1);
new_line(lexer);
}
}
static token_t* lexer_str(lexer_t* lexer) {
size_t str_len = 0;
while (true) {
if (!can_adv(lexer, 1)) {
error_new(lexer->errors, lexer->len, lexer->pos, "Unterminated string.");
return NULL;
}
else if (lexer_look(lexer, 1) == '\"') {
lexer_adv(lexer, 2);
break;
}
else {
lexer_adv(lexer, 1);
str_len++;
}
}
char* string = malloc(str_len + 1);
for (size_t idx = 0; idx < str_len; idx++)
string[idx] = lexer->src[lexer->ptr - str_len + idx];
string[str_len] = '\0';
token_t* token = token_new(lexer, _str);
token->string = string;
return token;
}
static token_t* lexer_float(lexer_t* lexer, token_t* token, size_t v) {
size_t places = 0;
double d = v;
if (!isdigit(lexer_look(lexer, 1))) { return token; }
while (lexer->len > 0) {
char c = lexer_look(lexer, 1);
if (isdigit(c)) {
lexer_adv(lexer, 1);
d = (d * 10) + (c - '0');
places++;
} else
break;
}
token->flt = d / (places * 10);
token->string = "";
return token;
}
static token_t* lexer_num(lexer_t* lexer) {
token_t* token = token_new(lexer, _int);
size_t v = 0;
while (can_adv(lexer, 1)) {
char c = lexer_look(lexer, 0);
if (isdigit(c)) {
v = (v * 10) + (c - '0');
lexer_adv(lexer, 1);
} else if (c == '.') {
lexer_adv(lexer, 1);
return lexer_float(lexer, token, v);
} else {
break;
}
}
token->integer = v;
token->string = "";
return token;
}
static token_t* lexer_ident(lexer_t* lexer) {
token_t* token = token_new(lexer, _ident);
size_t id_len = 0;
while (can_adv(lexer, 1)) {
if (!isalpha(lexer_look(lexer, 0)))
break;
lexer_adv(lexer, 1);
id_len++;
}
char* ident = malloc(id_len + 1);
for (size_t idx = 0; idx < id_len; idx++)
ident[idx] = lexer->src[lexer->ptr - id_len + idx];
ident[id_len] = '\0';
token->string = ident;
return token;
}
static token_t* next_token(lexer_t* lexer) {
token_t* token = NULL;
while (token == NULL && can_adv(lexer, 1)) {
const int c = lexer_look(lexer, 0);
if (DEBUG)
printf("Current character: \"%c\", Length: %d, Pointer: %d \n", lexer_look(lexer, 0), lexer->len, lexer->ptr);
switch (c) {
case '=':
if (lexer_look(lexer, 1) == '=') {
token = token_new(lexer, _eqto);
lexer_adv(lexer, 2);
token->string = "==";
} else {
token = token_new(lexer, _assign);
token->string = "=";
lexer_adv(lexer, 1);
}
break;
case '+':
if (lexer_look(lexer, 1) == '=') {
token = token_new(lexer, _addeql);
lexer_adv(lexer, 2);
token->string = "+=";
} else {
token = token_new(lexer, _add);
token->string = "+";
lexer_adv(lexer, 1);
}
break;
case '-':
if (lexer_look(lexer, 1) == '=') {
token = token_new(lexer, _subeql);
lexer_adv(lexer, 2);
token->string = "-=";
} else {
token = token_new(lexer, _sub);
token->string = "-";
lexer_adv(lexer, 1);
}
break;
case '*':
if (lexer_look(lexer, 1) == '=') {
token = token_new(lexer, _muleql);
lexer_adv(lexer, 2);
token->string = "*=";
} else {
token = token_new(lexer, _mul);
token->string = "*";
lexer_adv(lexer, 1);
}
break;
case '/':
if (lexer_look(lexer, 1) == '=') {
token = token_new(lexer, _diveql);
lexer_adv(lexer, 2);
token->string = "/=";
} else {
token = token_new(lexer, _div);
token->string = "/";
lexer_adv(lexer, 1);
}
break;
case '<':
if (lexer_look(lexer, 1) == '<') {
token = token_new(lexer, _nteq);
lexer_adv(lexer, 2);
token->string = "<=";
} else {
token = token_new(lexer, _bang);
token->string = "<";
lexer_adv(lexer, 1);
}
break;
case '>':
if (lexer_look(lexer, 1) == '<') {
token = token_new(lexer, _nteq);
lexer_adv(lexer, 2);
token->string = ">=";
}
else {
token = token_new(lexer, _bang);
token->string = ">";
lexer_adv(lexer, 1);
}
break;
case '&':
if (lexer_look(lexer, 1) == '&') {
token = token_new(lexer, _and);
lexer_adv(lexer, 2);
token->string = "&&";
} else {
token = token_new(lexer, _notype);
lexer_adv(lexer, 1);
}
break;
case '|':
if (lexer_look(lexer, 1) == '|') {
token = token_new(lexer, _or);
lexer_adv(lexer, 2);
token->string = "||";
}
else {
token = token_new(lexer, _notype);
lexer_adv(lexer, 1);
}
break;
case '%':
token = token_new(lexer, _mod);
token->string = "%";
lexer_adv(lexer, 1);
break;
case '^':
token = token_new(lexer, _mod);
token->string = "^";
lexer_adv(lexer, 1);
break;
case '!':
if (lexer_look(lexer, 1) == '=') {
token = token_new(lexer, _nteq);
lexer_adv(lexer, 2);
token->string = "!=";
}
else {
token = token_new(lexer, _bang);
token->string = "!";
lexer_adv(lexer, 1);
}
break;
case '\"':
token = lexer_str(lexer);
break;
case '#':
lexer_comment(lexer);
break;
case '(':
token = token_new(lexer, _lpara);
token->string = "(";
lexer_adv(lexer, 1);
break;
case ')':
token = token_new(lexer, _rpara);
token->string = ")";
lexer_adv(lexer, 1);
break;
case '{':
token = token_new(lexer, _lcurl);
token->string = "{";
lexer_adv(lexer, 1);
break;
case '}':
token = token_new(lexer, _rcurl);
token->string = "}";
lexer_adv(lexer, 1);
break;
case '[':
token = token_new(lexer, _lbrac);
token->string = "[";
lexer_adv(lexer, 1);
break;
case ']':
token = token_new(lexer, _rbrac);
token->string = "]";
lexer_adv(lexer, 1);
break;
case ';':
token = token_new(lexer, _terml);
token->string = ";";
lexer_adv(lexer, 1);
break;
default:
if (isalpha(c) || c == '_')
token = lexer_ident(lexer);
else if (isdigit(c) || c == '.') {
token = lexer_num(lexer);
} else if (isspace(c))
lexer_adv(lexer, 1);
else
token = token_new(lexer, _eof);
break;
}
}
return token;
}
void lexer_print(lexer_t* lexer) {
size_t line = lexer->line;
size_t pos = lexer->pos;
size_t ptr = lexer->ptr;
token_t* token = next_token(lexer);
while (token != NULL && token->type != _eof) {
token_print(token);
token = next_token(lexer);
}
lexer->ptr = ptr;
lexer->pos = pos;
}
lexer_t* lexer_open(const char* file_name) {
FILE* file_ptr = fopen(file_name, "rb");
lexer_t* lexer = malloc(sizeof(lexer_t));
lexer->errors = errorlist_new();
lexer->line = 1;
lexer->pos = 0;
lexer->ptr = 0;
if (file_ptr == NULL) {
error_new(lexer->errors, 0, 0, "Couldent open file \"%s\".\n", file_name);
fclose(file_ptr);
free(lexer);
}
if (fseek(file_ptr, 0, SEEK_END) != 0) {
fclose(file_ptr);
return NULL;
}
lexer->len = ftell(file_ptr);
if (lexer->len == -1) {
error_new(lexer->errors, 0, 0, "Unable to get the size of file \"%s\".\n", file_name);
fclose(file_ptr);
free(lexer);
}
fseek(file_ptr, 0, SEEK_SET);
lexer->src = malloc(lexer->len);
size_t r = fread(lexer->src, lexer->len, 1, file_ptr);
fclose(file_ptr);
return lexer;
}
void lexer_close(lexer_t* lexer) {
if (lexer->src != NULL)
free(lexer->src);
free(lexer);
}
为什么是size_t的问题是因为它们不需要负数，因为否则在解析器中处理而不是词法分析器。
#ifndef LEXER_H
#define LEXER_H
#include "error.h"
#include <stdio.h>
#include <stdbool.h>
#include <malloc.h>
#include <assert.h>
typedef enum tk_type {
// primitives
_notype,
_str,
_gen_num,
_ident,
_type,
// symbols
_rbrac,
_lbrac,
_rpara,
_lpara,
_rcurl,
_lcurl,
_terml,
_assign,
_bang,
_add,
_addeql,
_sub,
_subeql,
_div,
_diveql,
_mul,
_muleql,
_exp,
_mod,
// comparison operators
_lt,
_lteq,
_gt,
_gteq,
_eqto,
_nteq,
_and,
_or,
// keywords
_while,
_for,
_if,
_else,
_match,
_case,
_return,
_break,
_int,
_float,
_enum,
_true,
_false,
_import,
_struct,
_mac,
_dbl,
_void,
_char,
_bool,
_const,
// abstract
_block,
_eof
} tk_type;
typedef struct token_t {
tk_type type;
size_t line;
size_t pos;
union {
char* string;
double flt;
size_t integer;
};
} token_t;
typedef struct lexer_t {
size_t line;
size_t pos;
size_t ptr;
size_t len;
char* src;
errorlist_t* errors;
} lexer_t;
void lexer_print(lexer_t* lexer);
#endif
代码：
int main() {
int var = 10 + 2;
}
标题
{{1}}
输入
{{1}}
答案 0 :(得分：1)
lexer_int中的明显问题似乎就在最后：
token->integer = v;
token->string = "";
由于token_t包含覆盖integer，flt和string字段的匿名联合，因此会存储读取的数字，然后立即用指向静态的指针覆盖它字符串文字""。您想要删除token->string = "";行。
当然，那么你的token_print例程可能会崩溃，因为即使令牌不是字符串，它也会尝试读取string字段。
lexer_float有同样的问题...