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Define detail::unsafe_get, use it in visit

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Peter Dimov
2019-02-22 03:21:56 +02:00
parent 831231a8b3
commit f4d852e5ab
1 changed files with 42 additions and 11 deletions
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53
include/boost/variant2/variant.hpp
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@ -312,6 +312,37 @@ template<std::size_t I, class... T> constexpr variant_alternative_t<I, variant<T
#endif #endif
} }
// detail::unsafe_get (for visit)
namespace detail
{
template<std::size_t I, class... T> constexpr variant_alternative_t<I, variant<T...>>& unsafe_get(variant<T...>& v)
{
static_assert( I < sizeof...(T), "Index out of bounds" );
return v._get_impl( mp11::mp_size_t<I>() );
}
template<std::size_t I, class... T> constexpr variant_alternative_t<I, variant<T...>>&& unsafe_get(variant<T...>&& v)
{
static_assert( I < sizeof...(T), "Index out of bounds" );
return std::move( v._get_impl( mp11::mp_size_t<I>() ) );
}
template<std::size_t I, class... T> constexpr variant_alternative_t<I, variant<T...>> const& unsafe_get(variant<T...> const& v)
{
static_assert( I < sizeof...(T), "Index out of bounds" );
return v._get_impl( mp11::mp_size_t<I>() );
}
template<std::size_t I, class... T> constexpr variant_alternative_t<I, variant<T...>> const&& unsafe_get(variant<T...> const&& v)
{
static_assert( I < sizeof...(T), "Index out of bounds" );
return std::move( v._get_impl( mp11::mp_size_t<I>() ) );
}
} // namespace detail
// get (type) // get (type)
template<class U, class... T> constexpr U& get(variant<T...>& v) template<class U, class... T> constexpr U& get(variant<T...>& v)
@ -1589,32 +1620,32 @@ template<class T> using remove_cv_ref_t = typename std::remove_cv<typename std::
template<class T, class U> struct copy_cv_ref template<class T, class U> struct copy_cv_ref
{ {
using type = T; using type = T;
}; };
template<class T, class U> struct copy_cv_ref<T, U const> template<class T, class U> struct copy_cv_ref<T, U const>
{ {
using type = T const; using type = T const;
}; };
template<class T, class U> struct copy_cv_ref<T, U volatile> template<class T, class U> struct copy_cv_ref<T, U volatile>
{ {
using type = T volatile; using type = T volatile;
}; };
template<class T, class U> struct copy_cv_ref<T, U const volatile> template<class T, class U> struct copy_cv_ref<T, U const volatile>
{ {
using type = T const volatile; using type = T const volatile;
}; };
template<class T, class U> struct copy_cv_ref<T, U&> template<class T, class U> struct copy_cv_ref<T, U&>
{ {
using type = typename copy_cv_ref<T, U>::type&; using type = typename copy_cv_ref<T, U>::type&;
}; };
template<class T, class U> struct copy_cv_ref<T, U&&> template<class T, class U> struct copy_cv_ref<T, U&&>
{ {
using type = typename copy_cv_ref<T, U>::type&&; using type = typename copy_cv_ref<T, U>::type&&;
}; };
template<class T, class U> using copy_cv_ref_t = typename copy_cv_ref<T, U>::type; template<class T, class U> using copy_cv_ref_t = typename copy_cv_ref<T, U>::type;
@ -1647,7 +1678,7 @@ template<class F, class V1> struct visit_L1
template<class I> auto operator()( I ) const -> Vret<F, V1> template<class I> auto operator()( I ) const -> Vret<F, V1>
{ {
return std::forward<F>(f)( get<I::value>( std::forward<V1>(v1) ) ); return std::forward<F>(f)( unsafe_get<I::value>( std::forward<V1>(v1) ) );
} }
}; };
@ -1688,7 +1719,7 @@ template<class F, class V1, class V2> struct visit_L2
template<class I> auto operator()( I ) const -> Vret<F, V1, V2> template<class I> auto operator()( I ) const -> Vret<F, V1, V2>
{ {
auto f2 = bind_front( std::forward<F>(f), get<I::value>( std::forward<V1>(v1) ) ); auto f2 = bind_front( std::forward<F>(f), unsafe_get<I::value>( std::forward<V1>(v1) ) );
return visit( f2, std::forward<V2>(v2) ); return visit( f2, std::forward<V2>(v2) );
} }
}; };
@ -1713,7 +1744,7 @@ template<class F, class V1, class V2, class V3> struct visit_L3
template<class I> auto operator()( I ) const -> Vret<F, V1, V2, V3> template<class I> auto operator()( I ) const -> Vret<F, V1, V2, V3>
{ {
auto f2 = bind_front( std::forward<F>(f), get<I::value>( std::forward<V1>(v1) ) ); auto f2 = bind_front( std::forward<F>(f), unsafe_get<I::value>( std::forward<V1>(v1) ) );
return visit( f2, std::forward<V2>(v2), std::forward<V3>(v3) ); return visit( f2, std::forward<V2>(v2), std::forward<V3>(v3) );
} }
}; };
@ -1739,7 +1770,7 @@ template<class F, class V1, class V2, class V3, class V4> struct visit_L4
template<class I> auto operator()( I ) const -> Vret<F, V1, V2, V3, V4> template<class I> auto operator()( I ) const -> Vret<F, V1, V2, V3, V4>
{ {
auto f2 = bind_front( std::forward<F>(f), get<I::value>( std::forward<V1>(v1) ) ); auto f2 = bind_front( std::forward<F>(f), unsafe_get<I::value>( std::forward<V1>(v1) ) );
return visit( f2, std::forward<V2>(v2), std::forward<V3>(v3), std::forward<V4>(v4) ); return visit( f2, std::forward<V2>(v2), std::forward<V3>(v3), std::forward<V4>(v4) );
} }
}; };
@ -1757,7 +1788,7 @@ template<class F, class V1, class V2, class... V> constexpr auto visit( F&& f, V
{ {
return mp11::mp_with_index<variant_size<V1>>( v1.index(), [&]( auto I ){ return mp11::mp_with_index<variant_size<V1>>( v1.index(), [&]( auto I ){
auto f2 = [&]( auto&&... a ){ return std::forward<F>(f)( get<I.value>( std::forward<V1>(v1) ), std::forward<decltype(a)>(a)... ); }; auto f2 = [&]( auto&&... a ){ return std::forward<F>(f)( detail::unsafe_get<I.value>( std::forward<V1>(v1) ), std::forward<decltype(a)>(a)... ); };
return visit( f2, std::forward<V2>(v2), std::forward<V>(v)... ); return visit( f2, std::forward<V2>(v2), std::forward<V>(v)... );
}); });