Question

Using Boost.Spirit, is it possible to deliver a terminal token to multiple actions and if so, what would the syntax be?

For example, suppose I have two rules:
rule 1 that consumes “A B” and has an associated action “void f( <attribute type of A>, <attribute type of B>)” and rule 2 that consumes “B C” and has an associated action “void g( <attribute type of B>, <attribute type of C>)”.

Given the input stream “A1 B1 C1”, I want f(A1,B1) and g(B1,C1) to be invoked.

Edit: Some more research suggests using the And-Predicate may allow this.

Answer 1

Use local variables:

qi::rule<Iterator, qi::locals<B> > r = 
    (a >> b)[lf(_1, _2), _a  = _2] >> c[lg(_a, _1)];

I’m assuming here that lf() and lg() are lazy function (i.e. wrappers for your underlying f() and g()). See here for more information about locals. The disadvantage is that you make a copy of b’s attribute.