//
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// Copyright (c) 2018-2019, Cem Bassoy, cem.bassoy@gmail.com
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//
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// Distributed under the Boost Software License, Version 1.0. (See
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// accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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//
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// The authors gratefully acknowledge the support of
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// Fraunhofer IOSB, Ettlingen, Germany
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//
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#ifndef BOOST_UBLAS_TENSOR_MULTI_INDEX_UTILITY_HPP
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#define BOOST_UBLAS_TENSOR_MULTI_INDEX_UTILITY_HPP
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#include <tuple>
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#include <type_traits>
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namespace boost {
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namespace numeric {
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namespace ublas {
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namespace detail {
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template<class ... index_types>
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struct has_index_impl;
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template<class itype_left, class itype_right>
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struct has_index_impl<itype_left, itype_right>
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{
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static constexpr bool value = itype_left::value == itype_right::value;
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};
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template<class itype_left>
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struct has_index_impl <itype_left, std::tuple<> >
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{
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static constexpr bool value = false;
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};
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template<class itype_left, class itype_right>
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struct has_index_impl <itype_left, std::tuple<itype_right> >
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{
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static constexpr bool value = has_index_impl<itype_left,itype_right>::value;
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};
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template<class itype_left, class itype_right, class ... index_types>
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struct has_index_impl <itype_left, std::tuple<itype_right, index_types...> >
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{
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using next_type = has_index_impl<itype_left, std::tuple<index_types...>>;
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static constexpr bool value = has_index_impl<itype_left,itype_right>::value || next_type::value;
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};
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} // namespace detail
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/** @brief has_index is true if index occurs once or more in a multi-index
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*
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* @note a multi-index represents as tuple of single indexes of type boost::numeric::ublas::index::index_type
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*
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* @code auto has_index_value = has_index<index_type<1>, std::tuple<index_type<2>,index_type<1>> >::value; @endcode
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*
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* @tparam index_type type of index
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* @tparam tuple_type type of std::tuple representing a multi-index
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*/
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template<class index_type, class tuple_type>
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struct has_index
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{
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static constexpr bool value = detail::has_index_impl<std::decay_t<index_type>,std::decay_t<tuple_type>>::value;
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};
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} // namespace ublas
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} // namespace numeric
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} // namespace boost
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////////////////////////////////////////////////
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////////////////////////////////////////////////
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namespace boost {
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namespace numeric {
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namespace ublas {
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namespace detail {
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template<class ... index_types>
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struct valid_multi_index_impl;
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template<>
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struct valid_multi_index_impl<std::tuple<>>
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{
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static constexpr bool value = true;
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};
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template<class itype>
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struct valid_multi_index_impl<std::tuple<itype>>
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{
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static constexpr bool value = true;
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};
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template<class itype, class ... index_types>
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struct valid_multi_index_impl<std::tuple<itype,index_types...>>
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{
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using ttype = std::tuple<index_types...>;
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using has_index_type = has_index<itype, ttype>;
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static constexpr bool is_index_zero = itype::value==0ul;
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static constexpr bool has_index_value = has_index_type::value && !is_index_zero;
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static constexpr bool value = !has_index_value && valid_multi_index_impl<ttype>::value;
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};
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} // namespace detail
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/** @brief valid_multi_index is true if indexes occur only once in a multi-index
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*
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* @note a multi-index represents as tuple of single indexes of type boost::numeric::ublas::index::index_type
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*
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* @code auto valid = valid_multi_index< std::tuple<index_type<2>,index_type<1>> >::value;
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* @endcode
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*
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* @tparam tuple_type type of std::tuple representing a multi-index
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*/
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template<class tupe_type>
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struct valid_multi_index
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{
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static constexpr bool value = detail::valid_multi_index_impl<std::decay_t<tupe_type>>::value;
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};
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} // namespace ublas
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} // namespace numeric
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} // namespace boost
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////////////////////////////////////////////////
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////////////////////////////////////////////////
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namespace boost {
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namespace numeric {
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namespace ublas {
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namespace detail {
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template<class ... index_types >
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struct number_equal_indexes_impl;
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template<class ... itypes_right >
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struct number_equal_indexes_impl < std::tuple<>, std::tuple<itypes_right...>>
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{
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static constexpr unsigned value = 0;
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};
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template<class itype, class ... itypes_left, class ... itypes_right>
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struct number_equal_indexes_impl < std::tuple<itype,itypes_left...>, std::tuple<itypes_right...>>
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{
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using tuple_right = std::tuple<itypes_right...>;
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using has_index_type = has_index<itype, tuple_right>;
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static constexpr bool is_index_zero = itype::value==0ul;
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static constexpr bool has_index_value = has_index_type::value && !is_index_zero;
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using next_type = number_equal_indexes_impl< std::tuple<itypes_left...>, tuple_right >;
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static constexpr unsigned v = has_index_value ? 1 : 0;
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static constexpr unsigned value = v + next_type::value;
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};
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} // namespace detail
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/** @brief number_equal_indexes contains the number of equal indexes of two multi-indexes
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*
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* @note a multi-index represents as tuple of single indexes of type boost::numeric::ublas::index::index_type
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*
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*
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* @code auto num = number_equal_indexes<
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* std::tuple<index_type<2>,index_type<1>>,
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* std::tuple<index_type<1>,index_type<3>> >::value;
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* @endcode
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*
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* @tparam tuple_type_left type of left std::tuple representing a multi-index
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* @tparam tuple_type_right type of right std::tuple representing a multi-index
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*/
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template<class tuple_left, class tuple_right>
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struct number_equal_indexes
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{
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static constexpr unsigned value =
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detail::number_equal_indexes_impl< std::decay_t<tuple_left>, std::decay_t<tuple_right>>::value;
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};
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} // namespace ublas
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} // namespace numeric
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} // namespace boost
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////////////////////////////////////////////////
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////////////////////////////////////////////////
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namespace boost {
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namespace numeric {
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namespace ublas {
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namespace detail {
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template<std::size_t r, std::size_t m, class itype, class ttype>
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struct index_position_impl
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{
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static constexpr auto is_same = std::is_same< std::decay_t<itype>, std::decay_t<std::tuple_element_t<r,ttype>> >::value;
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static constexpr auto value = is_same ? r : index_position_impl<r+1,m,itype,ttype>::value;
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};
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template<std::size_t m, class itype, class ttype>
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struct index_position_impl < m, m, itype, ttype>
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{
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static constexpr auto value = std::tuple_size<ttype>::value;
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};
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} // namespace detail
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/** @brief index_position contains the zero-based index position of an index type within a multi-index
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*
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* @note a multi-index represents as tuple of single indexes of type boost::numeric::ublas::index::index_type
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*
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* @code auto num = index_position<
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* index_type<1>,
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* std::tuple<index_type<2>,index_type<1>> >::value;
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* @endcode
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*
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* @returns value returns 0 and N-1 if index_type is found, N otherwise where N is tuple_size_v<tuple_type>.
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*
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* @tparam index_type type of index
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* @tparam tuple_type type of std::tuple that is searched for index
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*/
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template<class index_type, class tuple_type>
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struct index_position
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{
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static constexpr auto value = detail::index_position_impl<0ul,std::tuple_size<tuple_type>::value,std::decay_t<index_type>,std::decay_t<tuple_type>>::value;
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};
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} // namespace ublas
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} // namespace numeric
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} // namespace boost
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////////////////////////////////////////////////
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////////////////////////////////////////////////
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namespace boost {
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namespace numeric {
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namespace ublas {
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namespace detail {
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template<std::size_t r, std::size_t m>
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struct index_position_pairs_impl
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{
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template<class array_type, class tuple_left, class tuple_right>
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static constexpr void run(array_type& out, tuple_left const& lhs, tuple_right const& rhs, std::size_t p)
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{
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using index_type = std::tuple_element_t<r-1,tuple_left>;
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using has_index_type = has_index<index_type, tuple_right>;
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using get_index_type = index_position<index_type,tuple_right>;
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using next_type = index_position_pairs_impl<r+1,m>;
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if constexpr ( has_index_type::value && index_type::value != 0)
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out[p++] = std::make_pair(r-1,get_index_type::value);
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next_type::run( out, lhs, rhs, p );
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}
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};
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template<std::size_t m>
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struct index_position_pairs_impl<m,m>
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{
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template<class array_type, class tuple_left, class tuple_right>
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static constexpr void run(array_type& out, tuple_left const& , tuple_right const& , std::size_t p)
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{
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using index_type = std::tuple_element_t<m-1,tuple_left>;
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using has_index_type = has_index<index_type, tuple_right>;
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using get_index_type = index_position<index_type, tuple_right>;
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if constexpr ( has_index_type::value && index_type::value != 0 )
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out[p] = std::make_pair(m-1,get_index_type::value);
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}
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};
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template<std::size_t r>
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struct index_position_pairs_impl<r,0>
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{
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template<class array_type, class tuple_left, class tuple_right>
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static constexpr void run(array_type&, tuple_left const& , tuple_right const& , std::size_t)
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{}
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};
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} // namespace detail
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/** @brief index_position_pairs returns zero-based index positions of matching indexes of two multi-indexes
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*
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* @note a multi-index represents as tuple of single indexes of type boost::numeric::ublas::index::index_type
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*
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* @code auto pairs = index_position_pairs(std::make_tuple(_a,_b), std::make_tuple(_b,_c));
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* @endcode
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*
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* @returns a std::array instance containing index position pairs of type std::pair<std::size_t, std::size_t>.
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*
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* @param lhs left std::tuple instance representing a multi-index
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* @param rhs right std::tuple instance representing a multi-index
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*/
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template<class tuple_left, class tuple_right>
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auto index_position_pairs(tuple_left const& lhs, tuple_right const& rhs)
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{
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using pair_type = std::pair<std::size_t,std::size_t>;
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constexpr auto m = std::tuple_size<tuple_left >::value;
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constexpr auto p = number_equal_indexes<tuple_left, tuple_right>::value;
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auto array = std::array<pair_type,p>{};
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detail::index_position_pairs_impl<1,m>::run(array, lhs, rhs,0);
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return array;
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}
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} // namespace ublas
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} // namespace numeric
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} // namespace boost
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////////////////////////////
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////////////////////////////
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////////////////////////////
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////////////////////////////
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namespace boost {
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namespace numeric {
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namespace ublas {
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namespace detail {
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template<class array_type, std::size_t ... R>
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constexpr auto array_to_vector_impl( array_type const& array, std::index_sequence<R...> )
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{
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return std::make_pair(
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std::vector<std::size_t>{std::get<0>( std::get<R>(array) )+1 ...} ,
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std::vector<std::size_t>{std::get<1>( std::get<R>(array) )+1 ...} );
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}
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} // namespace detail
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/** @brief array_to_vector converts a std::array of zero-based index position pairs into two std::vector of one-based index positions
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*
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* @code auto two_vectors = array_to_vector(std::make_array ( std::make_pair(1,2), std::make_pair(3,4) ) ) ;
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* @endcode
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*
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* @returns two std::vector of one-based index positions
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*
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* @param array std::array of zero-based index position pairs
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*/
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template<class pair_type, std::size_t N>
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constexpr auto array_to_vector( std::array<pair_type,N> const& array)
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{
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constexpr auto sequence = std::make_index_sequence<N>{};
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return detail::array_to_vector_impl( array, sequence );
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}
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} // namespace ublas
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} // namespace numeric
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} // namespace boost
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#endif // _BOOST_UBLAS_TENSOR_MULTI_INDEX_UTILITY_HPP_
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