reference_wrapper< T > Struct Template Reference

reference_wrapper is a class template that wraps a reference in a copyable, assignable object. It is frequently used as a mechanism to store references inside standard containers (like etl::static_vector) which cannot normally hold references. Specifically, reference_wrapper is a CopyConstructible and CopyAssignable wrapper around a reference to object or reference to function of type T. Instances of reference_wrapper are objects (they can be copied or stored in containers) but they are implicitly convertible to T&, so that they can be used as arguments with the functions that take the underlying type by reference. If the stored reference is Callable, reference_wrapper is callable with the same arguments. More...

#include <reference_wrapper.hpp>

Public Types
using	type = T

Public Member Functions
constexpr	reference_wrapper (reference_wrapper const &x) noexcept=default
	Constructs a new reference wrapper. Copy constructor. Stores a reference to other.get().
template<typename U , typename = decltype(detail::FUN<T>(declval<U>()), enable_if_t<!is_same_v<reference_wrapper, remove_cvref_t<U>>>())>
constexpr	reference_wrapper (U &&u) noexcept(noexcept(detail::FUN< T >(etl::forward< U >(u))))
	Constructs a new reference wrapper. Converts x to T& as if by T& t = etl::forward(x);, then stores a reference to t. This overload only participates in overload resolution if decay_t<U> is not the same type as reference_wrapper and the expression FUN(declval<U>()) is well-formed, where FUN names the set of imaginary functions:
constexpr auto	get () const noexcept -> type &
	Returns the stored reference.
constexpr	operator type & () const noexcept
	Returns the stored reference.
template<typename... Args>
constexpr auto	operator() (Args &&... args) const noexcept(noexcept(invoke(get(), etl::forward< Args >(args)...))) -> invoke_result_t< T &, Args... >
	Calls the Callable object, reference to which is stored. This function is available only if the stored reference points to a Callable object. T must be a complete type.
constexpr auto	operator= (reference_wrapper const &x) noexcept -> reference_wrapper &=default
	Copy assignment operator. Drops the current reference and stores a reference to other.get().

Detailed Description

template<typename T>
struct etl::reference_wrapper< T >

reference_wrapper is a class template that wraps a reference in a copyable, assignable object. It is frequently used as a mechanism to store references inside standard containers (like etl::static_vector) which cannot normally hold references. Specifically, reference_wrapper is a CopyConstructible and CopyAssignable wrapper around a reference to object or reference to function of type T. Instances of reference_wrapper are objects (they can be copied or stored in containers) but they are implicitly convertible to T&, so that they can be used as arguments with the functions that take the underlying type by reference. If the stored reference is Callable, reference_wrapper is callable with the same arguments.

Member Typedef Documentation

type

template<typename T >

using type = T

Constructor & Destructor Documentation

reference_wrapper() [1/2]

template<typename T >

template<typename U , typename = decltype(detail::FUN<T>(declval<U>()), enable_if_t<!is_same_v<reference_wrapper, remove_cvref_t<U>>>())>

constexpr reference_wrapper ( U &&  u )

inlineconstexprnoexcept

Constructs a new reference wrapper. Converts x to T& as if by T& t = etl::forward(x);, then stores a reference to t. This overload only participates in overload resolution if decay_t<U> is not the same type as reference_wrapper and the expression FUN(declval<U>()) is well-formed, where FUN names the set of imaginary functions:

void FUN(T&) noexcept;
void FUN(T&&) = delete;

https://en.cppreference.com/w/cpp/utility/functional/reference_wrapper/reference_wrapper

reference_wrapper() [2/2]

template<typename T >

constexpr reference_wrapper ( reference_wrapper< T > const &  x )

constexprdefaultnoexcept

Constructs a new reference wrapper. Copy constructor. Stores a reference to other.get().

Member Function Documentation

get()

template<typename T >

constexpr auto get ( ) const -> type&

inlineconstexprnoexcept

Returns the stored reference.

operator type &()

template<typename T >

constexpr operator type & ( ) const

inlineconstexprnoexcept

Returns the stored reference.

operator()()

template<typename T >

template<typename... Args>

constexpr auto operator() ( Args &&...  args ) const -> invoke_result_t<T&, Args...>

inlineconstexprnoexcept

Calls the Callable object, reference to which is stored. This function is available only if the stored reference points to a Callable object. T must be a complete type.

Returns

The return value of the called function.

operator=()

template<typename T >

constexpr auto operator= ( reference_wrapper< T > const &  x ) -> reference_wrapper &=default

constexprdefaultnoexcept

Copy assignment operator. Drops the current reference and stores a reference to other.get().

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The documentation for this struct was generated from the following file:

• include/etl/_functional/reference_wrapper.hpp