Parsing a set number of repetitions

Hi,

I'm struggling to find a satisfying solution for this seemingly simple 
problem:
Given a number of repetitions to follow, i want the parser to succeed 
only if this number is matched exactly.
I tried the following, which succesfully fails if there are too little 
occurences:

steps = step % +qi::eol;
step  = qi::omit[qi::int_[qi::_a = qi::_1] > qi::eol]
         > atoms(qi::_a);
atoms = qi::repeat(qi::_r1)[qi::eol > atom];

With too many atoms, it parses the first step, fails the second and ends.
In this specific case, i could rewrite the steps-rule to be more 
explicit in it's expectations, but i'd like to reuse this concept for 
formats where this is not possible.
Is there a way to fail the 'step' rule inside of itself given a mismatch 
of 'qi::_a' and the size of the parsed vector?
I also tried to use phoenix, as in:

steps = step % +qi::eol;
step  = qi::omit[qi::int_[qi::_a = qi::_1] > qi::eol]
         > atoms[qi::_b = phx::stl::size(qi::_1)]
         > qi::eps(qi::_a == qi::_b)
atoms = atom % qi::eol;

This does not compile though:
/usr/include/boost/phoenix/stl/container/container.hpp:735:16: note: 
candidate: constexpr boost::phoenix::stl::size::size()
          struct size
                 ^~~~
/usr/include/boost/phoenix/stl/container/container.hpp:735:16: note:   
candidate expects 0 arguments, 1 provided
/usr/include/boost/phoenix/stl/container/container.hpp:735:16: note: 
candidate: constexpr boost::phoenix::stl::size::size(const 
boost::phoenix::stl::size&)
/usr/include/boost/phoenix/stl/container/container.hpp:735:16: note:   
no known conversion for argument 1 from 'const _1_type {aka const 
boost::phoenix::actor<boost::spirit::argument<0> >}' to 'const 
boost::phoenix::stl::size&'
/usr/include/boost/phoenix/stl/container/container.hpp:735:16: note: 
candidate: constexpr 
boost::phoenix::stl::size::size(boost::phoenix::stl::size&&)
/usr/include/boost/phoenix/stl/container/container.hpp:735:16: note:   
no known conversion for argument 1 from 'const _1_type {aka const 
boost::phoenix::actor<boost::spirit::argument<0> >}' to 
'boost::phoenix::stl::size&&'

What am i missing?

Thank you,
Sebastian

------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most 
engaging tech sites, SlashDot.org! http://sdm.link/slashdot