std::incrementable_traits
Defined in header <iterator> | ||
|---|---|---|
template< class I >
struct incrementable_traits {};
| (1) | (since C++20) |
template< class T >
requires std::is_object_v<T>
struct incrementable_traits<T*>;
| (2) | (since C++20) |
template< class T >
struct incrementable_traits<const T>
: incrementable_traits<T> {};
| (3) | (since C++20) |
template< class T >
requires requires { typename T::difference_type; }
struct incrementable_traits<T>;
| (4) | (since C++20) |
template< class T >
requires (!requires { typename T::difference_type; }) &&
requires(const T& a, const T& b) { { a - b } -> std::integral; }
struct incrementable_traits<T>;
| (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
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) |
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