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Emplace

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This commit is contained in:
Simon Brand
2017-09-29 20:19:43 +01:00
parent 4fc7d9cf61
commit 3c0369cc83
1 changed files with 16 additions and 3 deletions
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19
optional.hpp
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@@ -242,8 +242,21 @@ class optional : private detail::optional_base<T> {
template <class U = T> optional& operator=(U&&); template <class U = T> optional& operator=(U&&);
template <class U> optional& operator=(const optional<U>&); template <class U> optional& operator=(const optional<U>&);
template <class U> optional& operator=(optional<U>&&); template <class U> optional& operator=(optional<U>&&);
template <class... Args> T& emplace(Args&&...);
template <class U, class... Args> T& emplace(initializer_list<U>, Args&&...); template <class... Args> T& emplace(Args&&...) {
static_assert(std::is_constructible<T, Args&&...>::value,
"T must be constructible with Args");
*this = nullopt;
new (std::addressof(m_storage.t)) T(std​::​forward<Args>(args)...);
}
template <class U, class... Args>
tl::enable_if_t<std::is_constructible<T, std::initializer_list<U>&, Args&&...>::value, T&>
T& emplace(initializer_list<U>, Args&&...) {
*this = nullopt;
new (std::addressof(m_storage.t)) T(il, std​::​forward<Args>(args)...);
}
// [optional.swap], swap // [optional.swap], swap
void swap(optional& rhs) void swap(optional& rhs)
@@ -260,7 +273,7 @@ class optional : private detail::optional_base<T> {
} }
} }
else if (rhs.has_value()) { else if (rhs.has_value()) {
new (&m_storage.t) T (std::move(rhs.m_storage.t)); new (std::addressof(m_storage.t)) T (std::move(rhs.m_storage.t));
rhs.m_storage.t.T::~T(); rhs.m_storage.t.T::~T();
} }
} }