std::incrementable_traits
From cppreference.com
| Defined in header <iterator>
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| template< class I > struct incrementable_traits {}; |
(1) | (since C++20) |
| template< class T > requires std::is_object_v<T> |
(2) | (since C++20) |
| template< class T > struct incrementable_traits<const T> |
(3) | (since C++20) |
| template< class T > requires requires { typename T::difference_type; } |
(4) | (since C++20) |
| template< class T > requires (!requires { typename T::difference_type; }) && |
(5) | (since C++20) |
Computes the associated difference type of the type I, if any. A program may specialize incrementable_traits for a program-defined type.
1) Primary template is an empty struct.
2) Specialization for pointers.
Provides a member type
difference_type same as std::ptrdiff_t.3) Specialization for const-qualified types.
4) Specialization for types that define a public and accessible member type
difference_type. Provides a member type
difference_type same as T::difference_type.5) Specialization for types that do not define a public and accessible member type
difference_type but do support subtraction. Provides a member type
difference_type same as std::make_signed_t<decltype(std::declval<T>() - std::declval<T>())>. The implicit expression variations rule (see below) applies to the expression a - b.Implicit expression variations
A requires expression that uses an expression that is non-modifying for some constant lvalue operand also requires implicit expression variations.
Example
| This section is incomplete Reason: no example |
See also
| (C++20) |
specifies that a semiregular type can be incremented with pre- and post-increment operators (concept) |
| (C++20)(C++20)(C++23)(C++20)(C++20)(C++20) |
computes the associated types of an iterator (alias template) |
| provides uniform interface to the properties of an iterator (class template) |