CODEWITHSUNDEEP
regextokenizeflex-lexer
gorilon
gorilon

Reputation: 434

Referencing a definition name in flex

Is there a way in flex to reference definition names in the action part of a matched pattern, similar to how you reference to the pattern itself? I would like something similar to 

%{
#include<stdio.h> 
}%

DIGIT [0-9]

%%

{DIGIT} printf("%s is a %s", yytext, yydefinition)

%%

int main(){

yylex(); return 0; 
}

I can imagine that the problem with this might be when you have multiple definitions in a rule such as {DIGIT} | {STRING}.

Upvotes: 1

Views: 315

Answers (1)

Thomas Dickey
Thomas Dickey

Reputation: 54563

No: lex (and flex) compile the contents of named patterns into tables without providing a way to refer to their names in the lexer.

There is not a lot of help with states (aka start conditions). lex/flex simply generate #define statements for those names.

flex has a debug switch, but the generated tables for that still do not include the information you want.

yacc and bison, on the other hand, have tables which can be used to help with error messages. The cproto program uses that feature, adjusting for several variations of yacc and bison.

Upvotes: 2

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