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- // Copyright 2019 Peter Dimov
- //
- // Distributed under the Boost Software License, Version 1.0.
- //
- // See accompanying file LICENSE_1_0.txt or copy at
- // http://www.boost.org/LICENSE_1_0.txt
- #if defined(ONLY_V2)
- # define NO_BV
- # define NO_SV
- #endif
- #if defined(ONLY_BV)
- # define NO_V2
- # define NO_SV
- #endif
- #if defined(ONLY_SV)
- # define NO_V2
- # define NO_BV
- #endif
- #if !defined(NO_V2)
- #include <boost/variant2/variant.hpp>
- #endif
- #if !defined(NO_BV)
- #include <boost/variant.hpp>
- #endif
- #if !defined(NO_SV)
- #include <variant>
- #endif
- #include <type_traits>
- #include <chrono>
- #include <iostream>
- #include <iomanip>
- #include <vector>
- #include <map>
- #include <string>
- #include <stdexcept>
- template<class T> struct is_numeric: std::integral_constant<bool, std::is_integral<T>::value || std::is_floating_point<T>::value>
- {
- };
- template<class T, class U> struct have_addition: std::integral_constant<bool, is_numeric<T>::value && is_numeric<U>::value>
- {
- };
- template<class T, class U, class E = std::enable_if_t<have_addition<T, U>::value>> auto add( T const& t, U const& u )
- {
- return t + u;
- }
- template<class T, class U, class E = std::enable_if_t<!have_addition<T, U>::value>> double add( T const& /*t*/, U const& /*u*/ )
- {
- throw std::logic_error( "Invalid addition" );
- }
- inline double to_double( double const& v )
- {
- return v;
- }
- #if !defined(NO_V2)
- template<class... T> boost::variant2::variant<T...> operator+( boost::variant2::variant<T...> const& v1, boost::variant2::variant<T...> const& v2 )
- {
- return visit( [&]( auto const& x1, auto const & x2 ) -> boost::variant2::variant<T...> { return add( x1, x2 ); }, v1, v2 );
- }
- template<class... T> double to_double( boost::variant2::variant<T...> const& v )
- {
- return boost::variant2::get<double>( v );
- }
- #endif
- #if !defined(NO_BV)
- template<class... T> boost::variant<T...> operator+( boost::variant<T...> const& v1, boost::variant<T...> const& v2 )
- {
- return boost::apply_visitor( [&]( auto const& x1, auto const & x2 ) -> boost::variant<T...> { return add( x1, x2 ); }, v1, v2 );
- }
- template<class... T> double to_double( boost::variant<T...> const& v )
- {
- return boost::get<double>( v );
- }
- #endif
- #if !defined(NO_SV)
- template<class... T> std::variant<T...> operator+( std::variant<T...> const& v1, std::variant<T...> const& v2 )
- {
- return visit( [&]( auto const& x1, auto const & x2 ) -> std::variant<T...> { return add( x1, x2 ); }, v1, v2 );
- }
- template<class... T> double to_double( std::variant<T...> const& v )
- {
- return std::get<double>( v );
- }
- #endif
- template<class V> void test_( long long N )
- {
- std::vector<V> w;
- // lack of reserve is deliberate
- auto tp1 = std::chrono::high_resolution_clock::now();
- for( long long i = 0; i < N; ++i )
- {
- V v;
- if( i % 7 == 0 )
- {
- v = i / 7;
- }
- else
- {
- v = i / 7.0;
- }
- w.push_back( v );
- }
- V s = 0.0;
- for( long long i = 0; i < N; ++i )
- {
- s = s + w[ i ];
- }
- auto tp2 = std::chrono::high_resolution_clock::now();
- std::cout << std::setw( 6 ) << std::chrono::duration_cast<std::chrono::milliseconds>( tp2 - tp1 ).count() << " ms; S=" << to_double( s ) << "\n";
- }
- template<class... T> void test( long long N )
- {
- std::cout << "N=" << N << ":\n";
- std::cout << " double: "; test_<double>( N );
- #if !defined(NO_V2)
- std::cout << " variant2: "; test_<boost::variant2::variant<T...>>( N );
- #endif
- #if !defined(NO_BV)
- std::cout << "boost::variant: "; test_<boost::variant<T...>>( N );
- #endif
- #if !defined(NO_SV)
- std::cout << " std::variant: "; test_<std::variant<T...>>( N );
- #endif
- std::cout << '\n';
- }
- int main()
- {
- long long const N = 100'000'000LL;
- test<long long, double>( N );
- test<std::nullptr_t, long long, double, std::string, std::vector<std::string>, std::map<std::string, std::string>>( N );
- }
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