Gokulakannan Somasundaram escribió:
Hi, In boost multi-index, can i verify whether a particular index type is ordered/not or not through meta programming? There are the ordered indexes, hash indexes, sequence indexes etc. Can i find them out through meta programming?
You can if you're given the multi_index_containr type and the position of the index: #include <boost/multi_index/ordered_index.hpp> #include <boost/mpl/at.hpp> #include <boost/mpl/bool.hpp> template<typename IndexSpecifier> struct is_ordered_index_impl:boost::mpl::false_{}; template<typename KeyFromValue,typename Compare> struct is_ordered_index_impl< boost::multi_index::ordered_unique<KeyFromValue,Compare>
:boost::mpl::true_{};
template<typename KeyFromValue,typename Compare> struct is_ordered_index_impl< boost::multi_index::ordered_non_unique<KeyFromValue,Compare>
:boost::mpl::true_{};
template<typename MultiIndexContainer,int N> struct is_ordered_index: is_ordered_index_impl< typename boost::mpl::at_c< typename MultiIndexContainer::index_specifier_type_list, N >::type > {}; /* testing */ #include <boost/multi_index_container.hpp> #include <boost/multi_index/sequenced_index.hpp> #include <boost/multi_index/hashed_index.hpp> #include <boost/multi_index/identity.hpp> #include <boost/mpl/assert.hpp> using namespace boost::multi_index; typedef multi_index_container< int, indexed_by< ordered_unique<identity<int> >, ordered_non_unique<identity<int> >, hashed_unique<identity<int> >, hashed_non_unique<identity<int> >, sequenced<> >
multi_t;
BOOST_MPL_ASSERT ((is_ordered_index<multi_t,0>)); BOOST_MPL_ASSERT ((is_ordered_index<multi_t,1>)); BOOST_MPL_ASSERT_NOT((is_ordered_index<multi_t,2>)); BOOST_MPL_ASSERT_NOT((is_ordered_index<multi_t,3>)); BOOST_MPL_ASSERT_NOT((is_ordered_index<multi_t,4>)); int main(){} HTH, Joaquín M López Muñoz Telefónica, Investigación y Desarrollo