forked from TartanLlama/optional
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Simon Brand
@ -697,11 +697,11 @@ public:
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/// \group and_then
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/// Carries out some operation which returns an optional on the stored
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/// object if there is one. \requires `std::invoke(std::forward<F>(f),
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/// value())` returns a `std::optional<U>` for some `U`. \returns Let `U` be
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/// the result of `std::invoke(std::forward<F>(f), value())`. Returns a
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/// `std::optional<U>`. The return value is empty if `*this` is empty,
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/// otherwise the return value of `std::invoke(std::forward<F>(f), value())`
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/// is returned.
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/// value())` returns a `std::optional<U>` for some `U`.
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/// \returns Let `U` be the result of `std::invoke(std::forward<F>(f),
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/// value())`. Returns a `std::optional<U>`. The return value is empty if
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/// `*this` is empty, otherwise the return value of
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/// `std::invoke(std::forward<F>(f), value())` is returned.
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/// \group and_then
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/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) &;
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template <class F>
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@ -834,7 +834,8 @@ public:
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/// \brief Calls `f` if the optional is empty
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/// \requires `std::invoke_result_t<F>` must be void or convertible to
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/// `optional<T>`. \effects If `*this` has a value, returns `*this`.
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/// `optional<T>`.
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/// \effects If `*this` has a value, returns `*this`.
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/// Otherwise, if `f` returns `void`, calls `std::forward<F>(f)` and returns
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/// `std::nullopt`. Otherwise, returns `std::forward<F>(f)()`.
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///
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@ -1089,8 +1090,7 @@ public:
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/// Constructs the stored value in-place using the given arguments.
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/// \group in_place
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/// \synopsis template <class... Args> constexpr explicit
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/// optional(in_place_t, Args&&... args);
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/// \synopsis template <class... Args> constexpr explicit optional(in_place_t, Args&&... args);
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template <class... Args>
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constexpr explicit optional(
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detail::enable_if_t<std::is_constructible<T, Args...>::value, in_place_t>,
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@ -1098,8 +1098,7 @@ public:
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: base(in_place, std::forward<Args>(args)...) {}
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/// \group in_place
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/// \synopsis template <class U, class... Args>\nconstexpr explicit
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/// optional(in_place_t, std::initializer_list<U>&, Args&&... args);
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/// \synopsis template <class U, class... Args>\nconstexpr explicit optional(in_place_t, std::initializer_list<U>&, Args&&... args);
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template <class U, class... Args>
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TL_OPTIONAL_11_CONSTEXPR explicit optional(
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detail::enable_if_t<std::is_constructible<T, std::initializer_list<U> &,
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@ -1246,7 +1245,8 @@ public:
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}
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/// Constructs the value in-place, destroying the current one if there is
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/// one. \group emplace
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/// one.
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/// \group emplace
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template <class... Args> T &emplace(Args &&... args) {
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static_assert(std::is_constructible<T, Args &&...>::value,
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"T must be constructible with Args");
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@ -1256,8 +1256,7 @@ public:
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}
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/// \group emplace
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/// \synopsis template <class U, class... Args>\nT&
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/// emplace(std::initializer_list<U> il, Args &&... args);
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/// \synopsis template <class U, class... Args>\nT& emplace(std::initializer_list<U> il, Args &&... args);
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template <class U, class... Args>
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detail::enable_if_t<
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std::is_constructible<T, std::initializer_list<U> &, Args &&...>::value,
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@ -1336,7 +1335,7 @@ public:
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/// \returns the contained value if there is one, otherwise throws
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/// [bad_optional_access]
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/// \group value
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/// synopsis constexpr T &value();
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/// \synopsis constexpr T &value();
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TL_OPTIONAL_11_CONSTEXPR T &value() & {
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if (has_value())
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return this->m_value;
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@ -1563,8 +1562,7 @@ inline constexpr bool operator>=(const U &lhs, const optional<T> &rhs) {
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return rhs.has_value() ? lhs >= *rhs : true;
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}
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/// \synopsis template <class T>\nvoid swap(optional<T> &lhs, optional<T>
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/// &rhs);
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/// \synopsis template <class T>\nvoid swap(optional<T> &lhs, optional<T> &rhs);
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template <class T,
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detail::enable_if_t<std::is_move_constructible<T>::value> * = nullptr,
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detail::enable_if_t<detail::is_swappable<T>::value> * = nullptr>
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@ -1599,12 +1597,28 @@ inline constexpr optional<T> make_optional(std::initializer_list<U> il,
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template <class T> optional(T)->optional<T>;
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#endif
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/// An optional object is an object that contains the storage for another
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/// object and manages the lifetime of this contained object, if any. The
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/// contained object may be initialized after the optional object has been
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/// initialized, and may be destroyed before the optional object has been
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/// destroyed. The initialization state of the contained object is tracked by
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/// the optional object.
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/// Specialization for when `T` is a reference. `optional<T&>` acts similarly
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/// to a `T*`, but provides more operations and shows intent more clearly.
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///
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/// *Examples*:
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///
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/// ```
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/// int i = 42;
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/// tl::optional<int&> o = i;
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/// *o == 42; //true
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/// i = 12;
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/// *o = 12; //true
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/// &*o == &i; //true
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/// ```
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///
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/// Assignment has rebind semantics rather than assign-through semantics:
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///
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/// ```
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/// int j = 8;
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/// o = j;
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///
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/// &*o == &j; //true
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/// ```
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template <class T> class optional<T &> {
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public:
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// The different versions for C++14 and 11 are needed because deduced return
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@ -2062,10 +2076,9 @@ public:
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/// Constructs the stored value with `u`.
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/// \synopsis template <class U=T> constexpr optional(U &&u);
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template <
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class U = T,
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detail::enable_if_t<!detail::is_optional<detail::decay_t<U>>::value> * =
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nullptr>
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template <class U = T,
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detail::enable_if_t<!detail::is_optional<detail::decay_t<U>>::value>
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* = nullptr>
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constexpr optional(U &&u) : m_value(std::addressof(u)) {
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static_assert(std::is_lvalue_reference<U>::value, "U must be an lvalue");
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}
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@ -2087,12 +2100,13 @@ public:
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/// Copy assignment.
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///
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/// Copies the value from `rhs` if there is one. Otherwise resets the stored
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/// value in `*this`.
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/// Rebinds this optional to the referee of `rhs` if there is one. Otherwise
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/// resets the stored value in `*this`.
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optional &operator=(const optional &rhs) = default;
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/// Assigns the stored value from `u`, destroying the old value if there was
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/// one.
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/// Rebinds this optional to `u`.
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///
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/// \requires `U` must be an lvalue reference.
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/// \synopsis optional &operator=(U &&u);
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template <class U = T,
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detail::enable_if_t<!detail::is_optional<detail::decay_t<U>>::value>
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@ -2105,17 +2119,17 @@ public:
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/// Converting copy assignment operator.
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///
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/// Copies the value from `rhs` if there is one. Otherwise resets the stored
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/// value in `*this`.
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/// \synopsis optional &operator=(const optional<U> & rhs);
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template <class U>
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optional &operator=(const optional<U> &rhs) {
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/// Rebinds this optional to the referee of `rhs` if there is one. Otherwise
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/// resets the stored value in `*this`.
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template <class U> optional &operator=(const optional<U> &rhs) {
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m_value = std::addressof(rhs.value());
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return *this;
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}
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/// Constructs the value in-place, destroying the current one if there is
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/// one. \group emplace
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/// one.
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///
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/// \group emplace
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template <class... Args> T &emplace(Args &&... args) noexcept {
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static_assert(std::is_constructible<T, Args &&...>::value,
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"T must be constructible with Args");
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