Question

我是初学者和野牛，所以请耐心等待。我正在尝试在yyerror中使用yylloc来打印错误发生的位置以及文件名。我知道这需要我重新定义YYLTPYE以包含一个char *文件名，我可以使用它来跟踪文件名。根据我所拥有的Flex和Bison的书，它建议我使用YY_USER_ACTION宏来初始化.l文件中的YYLTYPE，所以我在其中包含了以下内容，

#define YY_USER_ACTION yylloc.filename = filename; yylloc.hel = 0;  \
        yylloc.first_line = yylloc.last_line = yylineno;            \
        yylloc.first_column = yycolumn; yylloc.last_column = yycolumn+yyleng-1; \
        yycolumn += yyleng;

但是当我尝试编译项目时，我得到yylloc未声明的错误。

我已经尝试过克里斯·多德在question中提供的解决方案，但它并没有帮助我解决这个问题。解决此错误的任何和所有帮助都非常适用。

这是.l：

中的完整代码

%option noyywrap nodefault yylineno case-insensitive
%{
    #include "need.h"
    #include "numbers.tab.h"

    int yycolumn = 1;

    #define YY_USER_ACTION yylloc.filename = filename; yylloc.hel = 0;  \
        yylloc.first_line = yylloc.last_line = yylineno;            \
        yylloc.first_column = yycolumn; yylloc.last_column = yycolumn+yyleng-1; \
        yycolumn += yyleng;

%}

Integers    [-]?(0|[1-9][0-9]*)
Float       [.][0-9]+
Exp         [eE][-]?(0|[1-9][0-9]*)
Octal       [-]?(00|0[1-7][0-7]*)
Hexa        [-]?(0[xX][0-9A-F]+)
tomsNotNumbers [^ \t\n\v\f\r]+

%%

{Integers}{Float}?{Exp}?    {
                                printf("%s is a number.\n", yytext);
                                possibleNumbers++;  // increment by 1 as an input was given -M
                                actualNumbers++;    // increment by 1 as an input did match our pattern -M
                            }

{Octal} {
            printf("%s is a number.\n", yytext);
            possibleNumbers++;  // increment by 1 as an input was given -M
            actualNumbers++;    // increment by 1 as an input did match our pattern -M
        }

{Hexa}  {
            printf("%s is a number.\n", yytext);
            possibleNumbers++;  // increment by 1 as an input was given -M
            actualNumbers++;    // increment by 1 as an input did match our pattern -M
        }

{tomsNotNumbers}    {
                    printf("%s is not a number.\n", yytext);
                    yyerror(warning, "This isn't a number.");
                    possibleNumbers++;  // increment by 1 as an input was given -M
                    failedNumbers++;    // increment by 1 as the input has failed to match our patterns -M
                }

[\n]    /*Do nothing for newline*/

.   /*Do nothing for anything else*/

%%

.y现在只是空的，只有need.h的include和.tab.h的

need.h：

#include <stdlib.h>
#include <stdarg.h>
#include <string.h>

int possibleNumbers = 0;
int actualNumbers = 0;
int failedNumbers = 0;

typedef struct YYLTYPE
{
    int first_line;
    int first_column;
    int last_line;
    int last_column;
    char *filename; /* use to keep track of which file we're currently in */
    int hel;    /* no errors = 0, warning = 1, error = 2, fatal = 3 */
} YYLTYPE;

char *name; /*using for test purposes*/

# define YYLTYPE_IS_DECLARED 1

# define YYLLOC_DEFAULT(Current, Rhs, N)                                                    \
    do                                                                                      \
        if (N)                                                                              \
        {                                                                                   \
            (Current).first_line = YYRHSLOC (Rhs, 1).first_line;                            \
            (Current).first_column = YYRHSLOC (Rhs, 1).first_column;                        \
            (Current).last_line = YYRHSLOC (Rhs, N).last_line;                              \
            (Current).last_column = YYRHSLOC (Rhs, N).last_column;                          \
            (Current).filename = YYRHSLOC (Rhs, 1).filename;                                \
            (Current).hel   = YYRHSLOC (Rhs, 1).hel;                                        \
        }                                                                                   \
        else                                                                                \
        { /* empty RHS */                                                                   \
            (Current).first_line = (Current).last_line = YYRHSLOC (Rhs, 0).last_line;       \
            (Current).first_column = (Current).last_column = YYRHSLOC (Rhs, 0).last_column; \
            (Current).filename  = NULL;                                                     \
            (Current).hel = 0;                                                              \
        }                                                                                   \
    while (0)

typedef enum errorSeverity
{
    warning = 1, error, fatal
} errorLevel;

void yyerror(errorLevel errlvl, char *s, ...)
{
    va_list ap;
    va_start(ap, s);
    char *errLvls[3] = {"Warning", "Error", "Fatal"};  

    fprintf(stderr, "%s: %s: , %n", name, errLvls[errlvl - 1], yylloc.first_line);
    vfprintf(stderr, s, ap);
    fprintf(stderr, "\n");
}

main(int argc, char **argv)
{
    printf("argv[0] = %s, argv[1] = %s.\n", argv[0], argv[1]);
    if(argc > 1)
    {
        if((yyin = fopen(argv[1], "r")) == NULL)
        {
            perror(argv[1]);
            exit(1);
        }
        name = argv[1];
    } else
        name = "(stdin)";

    printf("Filename1: %s", name);
    yylex();
    printf("Filename2: %s", name);
    // print out the report. -M
    printf("Out of %d possible numbers, there were %d numbers, and %d not numbers.\n", possibleNumbers, actualNumbers, failedNumbers);
}

Answer 1

由于yylloc通常在野牛生成的解析器中定义，因此没有野牛输入文件会有点麻烦。

Bison将在生成的解析器中定义yylloc，并在生成的头文件中放置声明，如果：

您在bison序言中包含指令%locations，或
您在任何野牛行动中都会引用某个位置（@n为n）。

通常首选添加指令，以防在任何规则中没有明确引用位置。

正如Chris Dodd在链接问题中所说，在YYLTYPE生成bison生成的头文件之前包含#include的定义很重要。或者，您可以直接在#include部分的bison序言中插入结构的定义或适当的%code requires。 %code requires部分被复制到生成的标题中，这样就无需担心flex文件中的定义。

顺便说一下，我认为您打算使用YY_USER_INIT来初始化 yylloc。 {flex}扫描仪自己的初始化之前，YY_USER_INIT的扩展只执行一次。 YY_USER_ACTION的扩展在每个扫描程序操作（包括空操作）之前执行，并且可能有助于使用当前令牌更新yylloc结构。

如何解决yylloc未声明的错误？

1 个答案: