folly::rvalue_reference_wrapper< T > Class Template Reference

#include <RValueReferenceWrapper.h>

Public Types
using	type = T

Public Member Functions
	rvalue_reference_wrapper () noexcept
	rvalue_reference_wrapper (T &&ref) noexcept
	rvalue_reference_wrapper (T &) noexcept=delete
	rvalue_reference_wrapper (rvalue_reference_wrapper< T > &&other) noexcept
rvalue_reference_wrapper &	operator= (rvalue_reference_wrapper &&other) noexcept
	operator T && ()&&noexcept
T &&	get ()&&noexcept
template<class... Args>
decltype(auto)	operator() (Args &&...args)&&noexcept(noexcept(std::declval< T >()(std::forward< Args >(args)...)))
bool	valid () const noexcept

Private Member Functions
	rvalue_reference_wrapper (const rvalue_reference_wrapper &)=delete
rvalue_reference_wrapper &	operator= (const rvalue_reference_wrapper &)=delete

Private Attributes
T *	ptr_

Detailed Description

template<class T>
class folly::rvalue_reference_wrapper< T >

Class template that wraps a reference to an rvalue. Similar to std::reference_wrapper but with three important differences:

1) folly::rvalue_reference_wrappers can only be moved, not copied; 2) the get() function and the conversion-to-T operator are destructive and not const, they invalidate the wrapper; 3) the constructor-from-T is explicit.

These restrictions are designed to make it harder to accidentally create a a dangling rvalue reference, or to use an rvalue reference multiple times. (Using an rvalue reference typically implies invalidation of the target object, such as move-assignment to another object.)

folly::rref

Examples:

/facebook/proxygen/proxygen/folly/folly/container/Iterator.h.

Definition at line 42 of file RValueReferenceWrapper.h.

Member Typedef Documentation

template<class T>

using folly::rvalue_reference_wrapper< T >::type = T

Examples:

/facebook/proxygen/proxygen/folly/folly/lang/RValueReferenceWrapper.h.

Definition at line 44 of file RValueReferenceWrapper.h.

Constructor & Destructor Documentation

template<class T>

folly::rvalue_reference_wrapper< T >::rvalue_reference_wrapper ( )

inlinenoexcept

Default constructor. Creates an invalid reference. Must be move-assigned to in order to be come valid.

Examples:

/facebook/proxygen/proxygen/folly/folly/lang/RValueReferenceWrapper.h.

Definition at line 50 of file RValueReferenceWrapper.h.

Referenced by folly::rvalue_reference_wrapper< T >::rvalue_reference_wrapper(), and folly::rvalue_reference_wrapper< T >::valid().

: ptr_(nullptr) {}

template<class T>

folly::rvalue_reference_wrapper< T >::rvalue_reference_wrapper ( T &&  ref )

inlineexplicitnoexcept

Explicit constructor to make it harder to accidentally create a dangling reference to a temporary.

Definition at line 56 of file RValueReferenceWrapper.h.

References folly::pushmi::__adl::noexcept(), folly::rvalue_reference_wrapper< T >::rvalue_reference_wrapper(), and folly::T.

      : ptr_(std::addressof(ref)) {}

template<class T>

folly::rvalue_reference_wrapper< T >::rvalue_reference_wrapper ( T &  )

explicitdeletenoexcept

No construction from lvalue reference. Use std::move.

template<class T>

folly::rvalue_reference_wrapper< T >::rvalue_reference_wrapper ( rvalue_reference_wrapper< T > &&  other )

inlinenoexcept

Destructive move construction.

Definition at line 67 of file RValueReferenceWrapper.h.

      : ptr_(other.ptr_) {
    other.ptr_ = nullptr;
  }

template<class T>

folly::rvalue_reference_wrapper< T >::rvalue_reference_wrapper ( const rvalue_reference_wrapper< T > &  )

privatedelete

Member Function Documentation

template<class T>

T&& folly::rvalue_reference_wrapper< T >::get ( )

inlinenoexcept

Explicit unwrap. Destructive.

Definition at line 92 of file RValueReferenceWrapper.h.

References testing::Args(), folly::rvalue_reference_wrapper< T >::ptr_, folly::T, and folly::rvalue_reference_wrapper< T >::valid().

Referenced by folly::rvalue_reference_wrapper< T >::operator T &&(), and folly::rvalue_reference_wrapper< T >::operator()().

                        {
    assert(valid());
    T& ref = *ptr_;
    ptr_ = nullptr;
    return static_cast<T&&>(ref);
  }

template<class T>

folly::rvalue_reference_wrapper< T >::operator T && ( )

inlinenoexcept

Implicit conversion to raw reference. Destructive.

Definition at line 85 of file RValueReferenceWrapper.h.

References folly::rvalue_reference_wrapper< T >::get().

                                {
    return static_cast<rvalue_reference_wrapper&&>(*this).get();
  }

template<class T>

template<class... Args>

decltype(auto) folly::rvalue_reference_wrapper< T >::operator() ( Args &&...  args )

inlinenoexcept

Calls the callable object to whom reference is stored. Only available if the wrapped reference points to a callable object. Destructive.

Examples:

/facebook/proxygen/proxygen/folly/folly/lang/RValueReferenceWrapper.h.

Definition at line 104 of file RValueReferenceWrapper.h.

References folly::rvalue_reference_wrapper< T >::get().

                                                                     {
    return static_cast<rvalue_reference_wrapper&&>(*this).get()(
        std::forward<Args>(args)...);
  }

template<class T>

rvalue_reference_wrapper& folly::rvalue_reference_wrapper< T >::operator= ( rvalue_reference_wrapper< T > &&  other )

inlinenoexcept

Destructive move assignment.

Examples:

/facebook/proxygen/proxygen/folly/folly/lang/RValueReferenceWrapper.h.

Definition at line 75 of file RValueReferenceWrapper.h.

References folly::rvalue_reference_wrapper< T >::ptr_.

Referenced by folly::rvalue_reference_wrapper< T >::valid().

                                                 {
    ptr_ = other.ptr_;
    other.ptr_ = nullptr;
    return *this;
  }

template<class T>

rvalue_reference_wrapper& folly::rvalue_reference_wrapper< T >::operator= ( const rvalue_reference_wrapper< T > &  )

privatedelete

template<class T>

bool folly::rvalue_reference_wrapper< T >::valid ( ) const

inlinenoexcept

Check whether wrapped reference is valid.

Examples:

/facebook/proxygen/proxygen/folly/folly/lang/RValueReferenceWrapper.h.

Definition at line 113 of file RValueReferenceWrapper.h.

References folly::rvalue_reference_wrapper< T >::operator=(), folly::rvalue_reference_wrapper< T >::ptr_, and folly::rvalue_reference_wrapper< T >::rvalue_reference_wrapper().

Referenced by folly::rvalue_reference_wrapper< T >::get().

                              {
    return ptr_ != nullptr;
  }

Member Data Documentation

template<class T>

T* folly::rvalue_reference_wrapper< T >::ptr_

private

Examples:

/facebook/proxygen/proxygen/folly/folly/lang/RValueReferenceWrapper.h.

Definition at line 123 of file RValueReferenceWrapper.h.

Referenced by folly::rvalue_reference_wrapper< T >::get(), folly::rvalue_reference_wrapper< T >::operator=(), and folly::rvalue_reference_wrapper< T >::valid().

---

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

• proxygen/folly/folly/lang/RValueReferenceWrapper.h