mirror of
https://github.com/bolero-MURAKAMI/Sprout
synced 2024-11-12 21:09:01 +00:00
273 lines
8.7 KiB
C++
273 lines
8.7 KiB
C++
#ifndef SPROUT_VARIANT_VARIANT_HPP
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#define SPROUT_VARIANT_VARIANT_HPP
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#include <cstddef>
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#include <utility>
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#include <stdexcept>
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#include <type_traits>
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#include <sprout/config.hpp>
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#include <sprout/index_tuple.hpp>
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#include <sprout/utility/forward.hpp>
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#include <sprout/utility/move.hpp>
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#include <sprout/utility/swap.hpp>
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#include <sprout/tuple/tuple.hpp>
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#include <sprout/tuple/functions.hpp>
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#include <sprout/type/type_tuple.hpp>
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#include <sprout/type/algorithm/find_index.hpp>
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namespace sprout {
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template<typename... Types>
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class variant;
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namespace detail {
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template<typename... Types>
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class variant_impl {
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template<typename...>
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friend class variant;
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protected:
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typedef sprout::tuples::tuple<Types...> tuple_type;
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typedef sprout::types::type_tuple<typename std::decay<Types>::type...> uncvref_tuple_type;
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private:
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template<typename T, sprout::index_t... Indexes>
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static SPROUT_CONSTEXPR tuple_type init(T&& operand, sprout::index_tuple<Indexes...>) {
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return sprout::tuples::make<tuple_type>(
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typename sprout::tuples::tuple_element<Indexes, tuple_type>::type()...,
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sprout::forward<T>(operand)
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);
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}
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protected:
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tuple_type tuple_;
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int which_;
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protected:
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SPROUT_CONSTEXPR variant_impl()
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: tuple_()
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, which_()
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{}
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template<typename T, typename Index>
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SPROUT_CONSTEXPR variant_impl(T&& operand, Index)
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: tuple_(init(sprout::forward<T>(operand), sprout::index_range<0, Index::value>::make()))
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, which_(Index::value)
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{
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static_assert(Index::value < sizeof...(Types), "variant<>: invalid operand");
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}
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public:
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void swap(variant_impl& other)
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SPROUT_NOEXCEPT_EXPR(SPROUT_NOEXCEPT_EXPR(sprout::swap(tuple_, other.tuple_)))
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{
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sprout::swap(tuple_, other.tuple_);
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sprout::swap(which_, other.which_);
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}
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variant_impl& operator=(variant_impl const&) = default;
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};
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} // namespace detail
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//
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// variant
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//
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template<typename... Types>
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class variant
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: private sprout::detail::variant_impl<Types...>
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{
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private:
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typedef sprout::detail::variant_impl<Types...> impl_type;
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typedef typename impl_type::uncvref_tuple_type uncvref_tuple_type;
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public:
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typedef typename impl_type::tuple_type tuple_type;
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private:
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template<int I>
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static SPROUT_CONSTEXPR typename std::enable_if<
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I == sizeof...(Types),
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bool
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>::type eq(tuple_type const& l, tuple_type const& r, int which) {
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return false;
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}
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template<int I>
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static SPROUT_CONSTEXPR typename std::enable_if<
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I != sizeof...(Types),
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bool
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>::type eq(tuple_type const& l, tuple_type const& r, int which) {
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return I == which
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? sprout::tuples::get<I>(l) == sprout::tuples::get<I>(r)
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: eq<I + 1>(l, r, which)
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;
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}
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template<int I>
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static SPROUT_CONSTEXPR typename std::enable_if<
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static_cast<std::size_t>(I) == sizeof...(Types),
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bool
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>::type lt(tuple_type const& l, tuple_type const& r, int which) {
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return false;
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}
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template<int I>
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static SPROUT_CONSTEXPR typename std::enable_if<
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static_cast<std::size_t>(I) != sizeof...(Types),
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bool
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>::type lt(tuple_type const& l, tuple_type const& r, int which) {
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return I == which
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? sprout::tuples::get<I>(l) < sprout::tuples::get<I>(r)
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: lt<I + 1>(l, r, which)
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;
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}
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template<int I, typename Elem, typename Traits>
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static typename std::enable_if<
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static_cast<std::size_t>(I) == sizeof...(Types),
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std::basic_ostream<Elem, Traits>&
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>::type output(std::basic_ostream<Elem, Traits>& os, tuple_type const& t, int which) {
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return os;
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}
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template<int I, typename Elem, typename Traits>
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static typename std::enable_if<
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static_cast<std::size_t>(I) != sizeof...(Types),
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std::basic_ostream<Elem, Traits>&
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>::type output(std::basic_ostream<Elem, Traits>& os, tuple_type const& t, int which) {
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return I == which
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? os << sprout::tuples::get<I>(t)
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: output<I + 1>(os, t, which)
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;
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}
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template<int I, typename Tuple, typename Visitor>
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static SPROUT_CONSTEXPR typename std::enable_if<
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I == sizeof...(Types),
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typename Visitor::result_type
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>::type visit(Tuple&& t, Visitor&& v, int which) {
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return typename Visitor::result_type();
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}
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template<int I, typename Tuple, typename Visitor>
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static SPROUT_CONSTEXPR typename std::enable_if<
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I != sizeof...(Types),
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typename Visitor::result_type
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>::type visit(Tuple&& t, Visitor&& v, int which) {
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return I == which
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? sprout::forward<Visitor>(v)(sprout::tuples::get<I>(sprout::forward<Tuple>(t)))
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: visit<I + 1>(sprout::forward<Tuple>(t), sprout::forward<Visitor>(v), which)
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;
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}
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private:
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using impl_type::tuple_;
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using impl_type::which_;
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public:
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// construct/copy/destruct
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SPROUT_CONSTEXPR variant()
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: impl_type()
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{}
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variant(variant const&) = default;
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variant(variant&&) = default;
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template<typename T>
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SPROUT_CONSTEXPR variant(T&& operand)
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: impl_type(
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sprout::forward<T>(operand),
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sprout::types::find_index<uncvref_tuple_type, typename std::decay<T>::type>()
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)
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{}
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// modifiers
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void swap(variant& other)
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SPROUT_NOEXCEPT_EXPR(SPROUT_NOEXCEPT_EXPR(std::declval<impl_type&>().swap(other)))
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{
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impl_type::swap(other);
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}
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variant& operator=(variant const& rhs) {
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static_cast<impl_type&>(*this) = rhs;
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return *this;
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}
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variant& operator=(variant&& rhs)
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SPROUT_NOEXCEPT_EXPR(std::is_nothrow_move_assignable<impl_type>::value)
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{
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static_cast<impl_type&>(*this) = sprout::move(rhs);
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return *this;
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}
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template<typename T>
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variant& operator=(T&& rhs) {
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static_cast<impl_type&>(*this) = variant(sprout::forward<T>(rhs));
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return *this;
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}
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// queries
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SPROUT_CONSTEXPR int which() const {
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return which_;
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}
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SPROUT_CONSTEXPR bool empty() const {
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return false;
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}
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// relational
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friend SPROUT_CONSTEXPR bool operator==(variant const& lhs, variant const& rhs) {
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return lhs.which_ == rhs.which_ && eq<0>(lhs.tuple_, rhs.tuple_, lhs.which_);
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}
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friend SPROUT_CONSTEXPR bool operator!=(variant const& lhs, variant const& rhs) {
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return !(lhs == rhs);
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}
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friend SPROUT_CONSTEXPR bool operator<(variant const& lhs, variant const& rhs) {
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return lhs.which_ < rhs.which_
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|| (lhs.which_ == rhs.which_ && lt<0>(lhs.tuple_, rhs.tuple_, lhs.which_))
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;
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}
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friend SPROUT_CONSTEXPR bool operator>(variant const& lhs, variant const& rhs) {
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return rhs < lhs;
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}
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friend SPROUT_CONSTEXPR bool operator<=(variant const& lhs, variant const& rhs) {
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return !(rhs < lhs);
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}
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friend SPROUT_CONSTEXPR bool operator>=(variant const& lhs, variant const& rhs) {
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return !(lhs < rhs);
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}
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template<typename Elem, typename Traits>
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friend std::basic_ostream<Elem, Traits>& operator<<(std::basic_ostream<Elem, Traits>& lhs, variant const& rhs) {
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return output<0>(lhs, rhs.tuple_, rhs.which_);
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}
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// get support
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template<std::size_t I>
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SPROUT_CONSTEXPR typename std::enable_if<
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I != sizeof...(Types),
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typename sprout::tuples::tuple_element<I, tuple_type>::type const&
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>::type get_at() const {
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return I == static_cast<std::size_t>(which_)
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? sprout::tuples::get<I>(tuple_)
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: (throw std::domain_error("variant<>: bad get"), sprout::tuples::get<I>(tuple_))
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;
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}
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template<std::size_t I>
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typename std::enable_if<
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I != sizeof...(Types),
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typename sprout::tuples::tuple_element<I, tuple_type>::type&
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>::type get_at() {
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return I == which_
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? sprout::tuples::get<I>(tuple_)
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: (throw std::domain_error("variant<>: bad get"), sprout::tuples::get<I>(tuple_))
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;
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}
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template<typename U>
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SPROUT_CONSTEXPR typename std::enable_if<
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sprout::types::find_index<tuple_type, U>::value != sizeof...(Types),
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U const&
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>::type get() const {
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return get_at<sprout::types::find_index<tuple_type, U>::value>();
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}
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template<typename U>
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typename std::enable_if<
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sprout::types::find_index<tuple_type, U>::value != sizeof...(Types),
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U&
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>::type get() {
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return get_at<sprout::types::find_index<tuple_type, U>::value>();
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}
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// visitation support
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template<typename Visitor>
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SPROUT_CONSTEXPR typename Visitor::result_type apply_visitor(Visitor&& visitor) const {
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return visit<0>(tuple_, sprout::forward<Visitor>(visitor), which_);
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}
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template<typename Visitor>
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typename Visitor::result_type apply_visitor(Visitor&& visitor) {
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return visit<0>(tuple_, sprout::forward<Visitor>(visitor), which_);
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}
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};
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//
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// swap
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//
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template<typename... Types>
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inline void
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swap(sprout::variant<Types...>& lhs, sprout::variant<Types...>& rhs)
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SPROUT_NOEXCEPT_EXPR(SPROUT_NOEXCEPT_EXPR(lhs.swap(rhs)))
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{
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lhs.swap(rhs);
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}
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} // namespace sprout
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#endif // #ifndef SPROUT_VARIANT_VARIANT_HPP
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