std::experimental::ranges::value_type
From cppreference.com
| Defined in header <experimental/ranges/iterator>
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template< class I >
struct value_type {};
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(1) | |
template< class T >
struct value_type<T*>;
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(2) | |
template< class I >
requires std::is_array<I>::value
struct value_type<I> : value_type<std::decay_t<I>> {};
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(3) | |
template< class T >
struct value_type<const T> : value_type<std::decay_t<T>> {};
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(4) | |
template< class T >
requires requires { typename T::value_type; }
struct value_type<T>;
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(5) | |
template< class T >
requires requires { typename T::element_type; }
struct value_type<T>;
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(6) | |
Computes the associated value type of the type I, if any. Users may specialize value_type for a program-defined type.
1) Primary template is an empty struct.
2) Specialization for pointers. If
T is an object type, provides a member type type equal to std::remove_cv_t<T>. Otherwise, there is no member type.3) Specialization for array types.
4) Specialization for const-qualified types.
5) Specialization for types that define a public and accessible member type
value_type. If T::value_type is an object type, provides a member type type equal to T::value_type. Otherwise, there is no member type.6) Specialization for types that define a public and accessible member type
element_type (e.g., std::shared_ptr). If T::element_type is an object type, provides a member type type equal to std::remove_cv_t<typename T::element_type>. Otherwise, there is no member type.Helper alias template
template< class T >
using value_type_t = typename ranges::value_type<T>::type;
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(ranges TS) | |
Notes
If a type contains both a value_type member and a element_type member, then the specializations (5) and (6) are ambiguous.
value_type is intended for use with Readable types such as iterators. It is not intended for use with ranges.
Example
| This section is incomplete Reason: no example |