String input to flex lexer

Question

I want to create a read-eval-print loop using flex/bison parser. Trouble is, the flex generated lexer wants input of type FILE* and i would like it to be char*. Is there an

Answer 1

flex can parse char * using any one of three functions: yy_scan_string(), yy_scan_buffer(), and yy_scan_bytes() (see the documentation). Here's an example of the first:

typedef struct yy_buffer_state * YY_BUFFER_STATE;
extern int yyparse();
extern YY_BUFFER_STATE yy_scan_string(char * str);
extern void yy_delete_buffer(YY_BUFFER_STATE buffer);

int main(){
    char string[] = "String to be parsed.";
    YY_BUFFER_STATE buffer = yy_scan_string(string);
    yyparse();
    yy_delete_buffer(buffer);
    return 0;
}

The equivalent statements for yy_scan_buffer() (which requires a doubly null-terminated string):

char string[] = "String to be parsed.\0";
YY_BUFFER_STATE buffer = yy_scan_buffer(string, sizeof(string));

My answer reiterates some of the information provided by @dfa and @jlholland, but neither of their answers' code seemed to be working for me.