std::incrementable_traits

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< cpp‎ | iterator
Iterator library
Iterator concepts
Iterator primitives
(deprecated in C++17)
incrementable_traits
(C++20)


Algorithm concepts and utilities
Indirect callable concepts
Common algorithm requirements
(C++20)
(C++20)
(C++20)
Utilities
(C++20)
Iterator adaptors
Range access
(C++11)(C++14)
(C++14)(C++14)
(C++11)(C++14)
(C++14)(C++14)
(C++17)(C++20)
(C++17)
(C++17)
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

specifies that a semiregular type can be incremented with pre- and post-increment operators
(concept)
computes the associated types of an iterator
(alias template)
provides uniform interface to the properties of an iterator
(class template)