1 2 #ifndef BOOST_MPL_INDEX_IF_HPP_INCLUDED 3 #define BOOST_MPL_INDEX_IF_HPP_INCLUDED 4 5 // Copyright Eric Friedman 2003 6 // 7 // Distributed under the Boost Software License, Version 1.0. 8 // (See accompanying file LICENSE_1_0.txt or copy at 9 // http://www.boost.org/LICENSE_1_0.txt) 10 // 11 // See http://www.boost.org/libs/mpl for documentation. 12 13 // $Id$ 14 // $Date$ 15 // $Revision$ 16 17 #include <boost/mpl/aux_/find_if_pred.hpp> 18 #include <boost/mpl/begin_end.hpp> 19 #include <boost/mpl/if.hpp> 20 #include <boost/mpl/int.hpp> 21 #include <boost/mpl/iter_fold_if.hpp> 22 #include <boost/mpl/next.hpp> 23 #include <boost/mpl/void.hpp> 24 #include <boost/mpl/aux_/na_spec.hpp> 25 #include <boost/mpl/aux_/lambda_support.hpp> 26 #include <boost/type_traits/is_same.hpp> 27 28 namespace boost { namespace mpl { 29 30 template< 31 typename BOOST_MPL_AUX_NA_PARAM(Sequence) 32 , typename BOOST_MPL_AUX_NA_PARAM(Predicate) 33 > 34 struct index_if 35 { 36 typedef typename iter_fold_if< 37 Sequence 38 , int_<0> 39 , next<> 40 , aux::find_if_pred<Predicate> 41 >::type result_; 42 43 typedef typename end<Sequence>::type not_found_; 44 typedef typename first<result_>::type result_index_; 45 typedef typename second<result_>::type result_iterator_; 46 47 typedef typename if_< 48 is_same< result_iterator_,not_found_ > 49 , void_ 50 , result_index_ 51 >::type type; 52 53 BOOST_MPL_AUX_LAMBDA_SUPPORT(2,index_if,(Sequence,Predicate)) 54 }; 55 56 BOOST_MPL_AUX_NA_SPEC(2, index_if) 57 58 }} 59 60 #endif // BOOST_MPL_INDEX_IF_HPP_INCLUDED 61