...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
BOOST_PROTO_REPEAT_FROM_TO — Repeatedly invoke the specified macro.
// In header: <boost/proto/repeat.hpp>
BOOST_PROTO_REPEAT_FROM_TO(FROM, TO, MACRO)
BOOST_PROTO_REPEAT_FROM_TO()
is used to generate the kind of repetitive
code that is typical of DSELs built with Proto.
BOOST_PROTO_REPEAT_FROM_TO(
is equivalent to:
FROM
, TO
, MACRO
)
MACRO
(FROM
, BOOST_PROTO_typename_A, BOOST_PROTO_A_const_ref, BOOST_PROTO_A_const_ref_a, BOOST_PROTO_ref_a)MACRO
(FROM+1
, BOOST_PROTO_typename_A, BOOST_PROTO_A_const_ref, BOOST_PROTO_A_const_ref_a, BOOST_PROTO_ref_a) ...MACRO
(TO-1
, BOOST_PROTO_typename_A, BOOST_PROTO_A_const_ref, BOOST_PROTO_A_const_ref_a, BOOST_PROTO_ref_a)
Example:
// Generate BOOST_PROTO_MAX_ARITY-1 overloads of the // following construct() function template. #define M0(N, typename_A, A_const_ref, A_const_ref_a, ref_a) \ template<typename T, typename_A(N)> \ typename proto::result_of::make_expr< \ proto::tag::function \ , construct_helper<T> \ , A_const_ref(N) \ >::type const \ construct(A_const_ref_a(N)) \ { \ return proto::make_expr< \ proto::tag::function \ >( \ construct_helper<T>() \ , ref_a(N) \ ); \ } BOOST_PROTO_REPEAT_FROM_TO(1, BOOST_PROTO_MAX_ARITY, M0) #undef M0
The above invocation of BOOST_PROTO_REPEAT_FROM_TO()
will generate the following code:
template<typename T, typename A0> typename proto::result_of::make_expr< proto::tag::function , construct_helper<T> , A0 const & >::type const construct(A0 const & a0) { return proto::make_expr< proto::tag::function >( construct_helper<T>() , boost::ref(a0) ); } template<typename T, typename A0, typename A1> typename proto::result_of::make_expr< proto::tag::function , construct_helper<T> , A0 const & , A1 const & >::type const construct(A0 const & a0, A1 const & a1) { return proto::make_expr< proto::tag::function >( construct_helper<T>() , boost::ref(a0) , boost::ref(a1) ); } // ... and so on, up to BOOST_PROTO_MAX_ARITY-1 arguments ...