Re: Token redefinition

[Hans Aberg]

On 17 Nov 2006, at 10:05, Tim Van Holder wrote:

> > > I need to write a simple compiler for a pascal-like linguage, using
> > > flex and bison.
> > > The language uses token as "INT" "BOOL" or "FALSE"; when I  
> > > compile the
> > > project using
> > > Visual Studio 6.0 the following message is displayed:
> > >
> > > "'BOOL' : redefinition; typedef cannot be overloaded with any other
> > > symbol"
> > >
> > > This is because in windef.h they are other defines of tokens "INT"
> > > "BOOL" or "FALSE".
> > > How can I resolve the question WITHOUT change the names of the  
> > > tokens ??
> >
> > You can switch to a different platform.
>
> Or, as a more constructive suggestion, you could use a prefix for the
> token names in the grammar (T_BOOL, tBool, tokBOOL, etc. are all  
> viable
> alternatives).  And you can always give them string names you use  
> in the
> grammar:
>
> grammar:   %token t_BOOL "BOOL"
> lexer:     "BOOL" { return t_BOOL; }
> grammar:   some_rule: some_other_rule "BOOL";
>
> which ensures that bison syntax errors say they expect a BOOL rather
> than a t_BOOL (only the lexer has to use the t_* names). This is
> especially nice when the name for the token consists of multiple  
> words:
>
> %token t_DECIMAL_LITERAL "decimal literal"

You probably did not read the OP, who wants the macro names  
unchanged! The question seems to be how to avoid name clashes without  
changing their names. :-)

  Hans Aberg