將值傳遞給yylex

Question

所以我想避免全局變量，但我想使用Flex來標記輸入。我想知道是否有可能將一個值傳遞給yylex，以便我可以擺脫全局。

現在我有這個

%{ 
#include 
#include 
#include 
#include 
#include "lex.h" 
%} 

%option noyywrap 

digit  [0-9] 
alpha  [a-zA-Z] 
alphanum {alpha}|{digit}|"_" 

%% 
[\t\n ]     printf("WS:\n"); 
{alpha}{alphanum}*  printf("symbol: %s\n",yytext); 
{digit}+    printf("int: %s\n",yytext); 
{digit}+"."{digit}  printf("float: %s\n",yytext); 
"\"".*"\""    printf("litral: %s\n",yytext); 
"+"      printf("op: %s\n",yytext); 
"-"      printf("op: %s\n",yytext); 
"*"      printf("op: %s\n",yytext); 
"/"      printf("op: %s\n",yytext); 
"%"      printf("op: %s\n",yytext); 
"="     printf("op: %s\n",yytext); 
""      printf("op: %s\n",yytext); 
"=="     printf("op: %s\n",yytext); 
"!="     printf("op: %s\n",yytext); 
"("      printf("op: %s\n",yytext); 
")"      printf("op: %s\n",yytext); 
","      printf("op: %s\n",yytext); 
"="      printf("op: %s\n",yytext); 
%% 

void LexInit() { 
    Tokens = malloc(sizeof(TokenStream)); 
    Tokens->size=0; 
} 

void LexPush(const char* str) { 
    size_t size = strlen(str); 
    char* newstr = malloc(size*sizeof(char)); 
    realloc(Tokens->tokens,++Tokens->size*sizeof(char*)); 

} 

void Lex(const char* filepath) { 
    LexInit(); 
    yyin = fopen(filepath,"r"); 
    yylex(); 
} 

Answer 1

你應該閱讀文章涉及到折返和額外的類型選項。

/* An example of overriding YY_EXTRA_TYPE. */ 
    %{ 
    #include 
    #include 
    %} 
    %option reentrant 
    %option extra-type="struct stat *" 
    %% 

    __filesize__  printf("%ld", yyextra->st_size ); 
    __lastmod__  printf("%ld", yyextra->st_mtime); 
    %% 
    void scan_file(char* filename) 
    { 
     yyscan_t scanner; 
     struct stat buf; 
     FILE *in; 

     in = fopen(filename, "r"); 
     stat(filename, &buf); 

     yylex_init_extra(buf, &scanner); 
     yyset_in(in, scanner); 
     yylex(scanner); 
     yylex_destroy(scanner); 

     fclose(in); 
    } 

http://www.cse.yorku.ca/tdb/_doc.php/userg/man_g/file/flex/node/Extra%20Data