//
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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_HPP
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#define BOOST_UBLAS_TENSOR_MULTI_INDEX_HPP
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#include <cstddef>
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#include <array>
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#include <vector>
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#include "multi_index_utility.hpp"
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namespace boost {
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namespace numeric {
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namespace ublas {
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namespace index {
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template<std::size_t I>
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struct index_type;
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} // namespace indices
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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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/** @brief Proxy class for the einstein summation notation
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*
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* Denotes an array of index_type types ::_a for 0<=K<=16 is used in tensor::operator()
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*/
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template<std::size_t N>
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class multi_index
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{
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public:
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multi_index() = delete;
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template<std::size_t I, class ... indexes>
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constexpr multi_index(index::index_type<I> const& i, indexes ... is )
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: _base{i(), is()... }
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{
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static_assert( sizeof...(is)+1 == N,
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"Static assert in boost::numeric::ublas::multi_index: number of constructor arguments is not equal to the template parameter." );
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static_assert( valid_multi_index<std::tuple<index::index_type<I>, indexes ...> >::value,
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"Static assert in boost::numeric::ublas::multi_index: indexes occur twice in multi-index." );
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}
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multi_index(multi_index const& other)
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: _base(other._base)
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{
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}
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multi_index& operator=(multi_index const& other)
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{
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this->_base = other._base;
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return *this;
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}
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~multi_index() = default;
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auto const& base() const { return _base; }
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constexpr auto size() const { return _base.size(); }
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constexpr auto at(std::size_t i) const { return _base.at(i); }
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constexpr auto operator[](std::size_t i) const { return _base.at(i); }
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private:
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std::array<std::size_t, N> _base;
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};
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template<std::size_t K, std::size_t N>
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constexpr auto get(multi_index<N> const& m) { return std::get<K>(m.base()); }
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template<std::size_t M, std::size_t N>
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auto array_to_vector(multi_index<M> const& lhs, multi_index<N> const& rhs)
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{
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using vtype = std::vector<std::size_t>;
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auto pair_of_vector = std::make_pair( vtype {}, vtype{} );
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for(auto i = 0u; i < N; ++i)
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for(auto j = 0u; j < M; ++j)
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if ( lhs.at(i) == rhs.at(j) && lhs.at(i) != boost::numeric::ublas::index::_())
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pair_of_vector.first .push_back( i+1 ),
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pair_of_vector.second.push_back( j+1 );
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return pair_of_vector;
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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 // MULTI_INDEX_HPP
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