std::iter_value_t, std::iter_reference_t, std::iter_difference_t, std::iter_rvalue_reference_t, std::iter_common_reference_t
Defined in header <iterator> |
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template< class T > concept /*dereferenceable*/ = /* see below */; // exposition only |
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template< class T > using iter_value_t = /* see below */; |
(1) | (since C++20) |
template< /*dereferenceable*/ T > using iter_reference_t = decltype(*std::declval<T&>()); |
(2) | (since C++20) |
template< class T > using iter_difference_t = /* see below */; |
(3) | (since C++20) |
template< /*dereferenceable*/ T> requires /* see below */ using iter_rvalue_reference_t = decltype(ranges::iter_move(std::declval<T&>())); |
(4) | (since C++20) |
template< std::indirectly_readable T > using iter_common_reference_t = std::common_reference_t<std::iter_reference_t<T>, std::iter_value_t<T>&>; |
(5) | (since C++20) |
Compute the associated types of an iterator. The exposition-only concept dereferenceable
is satisfied if and only if the expression *std::declval<T&>()
is valid and has a referenceable type (in particular, not void
).
1) Computes the
value type of
T
. If
std::iterator_traits<std::remove_cvref_t<T>>
is not specialized, then
std::iter_value_t<T>
is
std::indirectly_readable_traits<std::remove_cvref_t<T>>::value_type
. Otherwise, it is
std::iterator_traits<std::remove_cvref_t<T>>::value_type
.
2) Computes the
reference type of
T
.
3) Computes the
difference type of
T
. If
std::iterator_traits<std::remove_cvref_t<T>>
is not specialized, then
std::iter_difference_t<T>
is
std::incrementable_traits<std::remove_cvref_t<T>>::difference_type
. Otherwise, it is
std::iterator_traits<std::remove_cvref_t<T>>::difference_type
.
4) Computes the
rvalue reference type of
T
. The "see below" portion of the constraint on this alias template is satisfied if and only if the expression
ranges::iter_move(std::declval<T&>())
is valid and has a referenceable type (in particular, not
void
).
5) Computes the
common reference type of
T
. This is the common reference type between its reference type and an lvalue reference to its value type.
See also
(C++20)
|
specifies that a type is indirectly readable by applying operator * (concept) |
(C++20)
|
specifies that a semiregular type can be incremented with pre- and post-increment operators (concept) |
(C++20)
|
computes the value type of an indirectly_readable type (class template) |
(C++20)
|
computes the difference type of a weakly_incrementable type (class template) |
provides uniform interface to the properties of an iterator (class template) |
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