yacc grammar and types

Who is the responsability of checking semantic value of a program? The
grammar parser or the interpreter/compiler itself. For example

Should i do it this way:

%union
{
int integer;
float real;
}

%token <integer> INT
%token <real> REAL

%%

expr : | INT
              | REAL
              | expr + expr
              | expr - expr
          ;

or should i use something like:

  expr : NUM
              | expr + expr { /* here i would determine the semantics of the
                                            expressions if it was a float or a int */ }
              | expr - expr
            ;

(used a very simple example)

Basically the question is, who has the burden of watching the semantics,
the parser or the "user" code.

--
                                                  Tiago Umm Pascoal
                                              l41484@alfa.ist.utl.pt
[You can do it either way. Which is easier or better depends on the language
you're parsing. -John]
--

Return to the comp.compilers page.
Search the comp.compilers archives again.