// Boost.Varaint
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// Contains multivisitors that are implemented via variadic templates, std::tuple
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// and decltype(auto)
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//
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// See http://www.boost.org for most recent version, including documentation.
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//
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// Copyright Antony Polukhin, 2013-2014.
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//
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// Distributed under the Boost
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// Software License, Version 1.0. (See accompanying file
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// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt).
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#ifndef BOOST_VARIANT_DETAIL_MULTIVISITORS_CPP14_BASED_HPP
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#define BOOST_VARIANT_DETAIL_MULTIVISITORS_CPP14_BASED_HPP
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#if defined(_MSC_VER)
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# pragma once
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#endif
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#include <boost/variant/detail/multivisitors_cpp14_based.hpp>
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#include <tuple>
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namespace boost {
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namespace detail { namespace variant {
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// Forward declaration
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template <typename Visitor, typename Visitables, typename... Values>
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class one_by_one_visitor_and_value_referer_cpp14;
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template <typename Visitor, typename Visitables, typename... Values>
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inline one_by_one_visitor_and_value_referer_cpp14<Visitor, Visitables, Values... >
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make_one_by_one_visitor_and_value_referer_cpp14(
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Visitor& visitor, Visitables visitables, std::tuple<Values...> values
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)
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{
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return one_by_one_visitor_and_value_referer_cpp14<Visitor, Visitables, Values... > (
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visitor, visitables, values
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);
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}
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template <typename Visitor, typename Visitables, typename... Values>
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class one_by_one_visitor_and_value_referer_cpp14
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{
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Visitor& visitor_;
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std::tuple<Values...> values_;
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Visitables visitables_;
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public: // structors
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one_by_one_visitor_and_value_referer_cpp14(
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Visitor& visitor, Visitables visitables, std::tuple<Values...> values
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) BOOST_NOEXCEPT
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: visitor_(visitor)
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, values_(values)
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, visitables_(visitables)
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{}
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public: // visitor interfaces
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template <typename Value>
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decltype(auto) operator()(Value&& value) const
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{
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return ::boost::apply_visitor(
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make_one_by_one_visitor_and_value_referer_cpp14(
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visitor_,
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tuple_tail(visitables_),
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std::tuple_cat(values_, std::make_tuple(wrap<Value, ! ::boost::is_lvalue_reference<Value>::value>(value)))
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)
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, unwrap(std::get<0>(visitables_)) // getting Head element
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);
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}
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private:
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one_by_one_visitor_and_value_referer_cpp14& operator=(const one_by_one_visitor_and_value_referer_cpp14&);
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};
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template <typename Visitor, typename... Values>
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class one_by_one_visitor_and_value_referer_cpp14<Visitor, std::tuple<>, Values...>
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{
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Visitor& visitor_;
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std::tuple<Values...> values_;
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public:
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one_by_one_visitor_and_value_referer_cpp14(
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Visitor& visitor, std::tuple<> /*visitables*/, std::tuple<Values...> values
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) BOOST_NOEXCEPT
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: visitor_(visitor)
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, values_(values)
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{}
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template <class Tuple, std::size_t... I>
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decltype(auto) do_call(Tuple t, index_sequence<I...>) const {
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return visitor_(unwrap(std::get<I>(t))...);
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}
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template <typename Value>
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decltype(auto) operator()(Value&& value) const
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{
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return do_call(
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std::tuple_cat(values_, std::make_tuple(wrap<Value, ! ::boost::is_lvalue_reference<Value>::value>(value))),
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make_index_sequence<sizeof...(Values) + 1>()
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);
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}
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};
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}} // namespace detail::variant
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template <class Visitor, class T1, class T2, class T3, class... TN>
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inline decltype(auto) apply_visitor(const Visitor& visitor, T1&& v1, T2&& v2, T3&& v3, TN&&... vn,
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typename boost::disable_if<
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boost::detail::variant::has_result_type<Visitor>,
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bool
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>::type = true)
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{
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return boost::apply_visitor(
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::boost::detail::variant::make_one_by_one_visitor_and_value_referer_cpp14(
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visitor,
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std::make_tuple(
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::boost::detail::variant::wrap<T2, ! ::boost::is_lvalue_reference<T2>::value>(v2),
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::boost::detail::variant::wrap<T3, ! ::boost::is_lvalue_reference<T3>::value>(v3),
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::boost::detail::variant::wrap<TN, ! ::boost::is_lvalue_reference<TN>::value>(vn)...
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),
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std::tuple<>()
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),
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::boost::forward<T1>(v1)
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);
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}
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template <class Visitor, class T1, class T2, class T3, class... TN>
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inline decltype(auto) apply_visitor(Visitor& visitor, T1&& v1, T2&& v2, T3&& v3, TN&&... vn,
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typename boost::disable_if<
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boost::detail::variant::has_result_type<Visitor>,
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bool
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>::type = true)
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{
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return ::boost::apply_visitor(
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::boost::detail::variant::make_one_by_one_visitor_and_value_referer_cpp14(
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visitor,
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std::make_tuple(
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::boost::detail::variant::wrap<T2, ! ::boost::is_lvalue_reference<T2>::value>(v2),
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::boost::detail::variant::wrap<T3, ! ::boost::is_lvalue_reference<T3>::value>(v3),
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::boost::detail::variant::wrap<TN, ! ::boost::is_lvalue_reference<TN>::value>(vn)...
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),
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std::tuple<>()
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),
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::boost::forward<T1>(v1)
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);
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}
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} // namespace boost
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#endif // BOOST_VARIANT_DETAIL_MULTIVISITORS_CPP14_BASED_HPP
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