Hi, I have the following toy flex code to generate a lexer.
I use rapidstring to make the string operations use and use the Boehm garbage collector so that I don't have to always remember to release the memory. https://github.com/boyerjohn/rapidstring Because I want to use the previously allocated memory, I don't want to call "rs_init(&yylval->str)" in any action. So YYSTYPE must be a struct instead of a union. Is it a good practice to use struct instead of union? Since %union cannot be used in this case, how to deal with this scenario in bison? Thanks. %{ #define TOK_NUMBER 1000 #define TOK_STRING 1001 #include <gc.h> #define RS_MALLOC GC_MALLOC #define RS_REALLOC GC_REALLOC #define RS_FREE GC_FREE #include <rapidstring.h> typedef struct { int num; rapidstring str; } YYSTYPE; %} %option nodefault noinput nounput %option reentrant bison-bridge %% [[:digit:]]+ yylval->num=atoi(yytext); return TOK_NUMBER; [[:alpha:]]+ { rs_cpy(&yylval->str, yytext); return TOK_STRING; } .|\n %% int main() { GC_INIT(); yyscan_t scanner; yylex_init(&scanner); int tok; YYSTYPE lval; rs_init(&lval.str); while((tok = yylex(&lval, scanner))) { if(tok == TOK_NUMBER) { printf("tok = %d, yylval= %d\n", tok, yyget_lval(scanner)->num); } else if(tok == TOK_STRING) { printf("tok = %d, yylval= %s\n", tok, rs_data(&yyget_lval(scanner)->str)); } } yylex_destroy(scanner); return 0; } -- Regards, Peng _______________________________________________ help-bison@gnu.org https://lists.gnu.org/mailman/listinfo/help-bison
