I'm trying to create simple Pascal compiler using Flex/Bison and I want to check what semantic values are stored withing tokens. I have following code for flex:
...
{ID} {yylval.stringValue= strdup(yytext); return(ID);}
...
And following code in bison:
...
program: PROGRAM ID LBRACKET identifier_list RBRACKET DELIM declarations subprogram_declarations compound_statement DOT {printf($2);}
...
And following test file:
program example(input, output);
...
Flex and bison recognize all perfectly and parse is ok, but if I want check token values like in code before it has no effect:
Starting parse
Entering state 0
Reading a token: Next token is token PROGRAM ()
Shifting token PROGRAM ()
Entering state 1
Reading a token: Next token is token ID ()
Shifting token ID ()
Entering state 3
Is there a way to print token value inside (), like token ID (example). I've checked similar questions and they do it the same way, or maybe I'm just missing something.
P.S. When I enable debug mode for flex it shows that it accepted "example" by rule {ID}, but where does that example stored and how should I use it in advance.
Bison cannot know for itself, where the semantic values shall be taken from. So
you have to define %printers for your tokens. In your case you have to define the type of the token and a corresponding printer:
%token <stringValue> ID
%printer { fprintf(yyoutput, "%s", $$); } ID;
Define one printer for each token, which you want to deep-inspect in traces, then it should work as you expect.