std::experimental::ranges::CommonReference(3) | C++ Standard Libary | std::experimental::ranges::CommonReference(3) |

# NAME¶

std::experimental::ranges::CommonReference - std::experimental::ranges::CommonReference

# Synopsis¶

Defined in header <experimental/ranges/concepts>

template < class T, class U >

concept bool CommonReference =

Same<ranges::common_reference_t<T, U>,
ranges::common_reference_t<U, (ranges TS)

T>> &&

ConvertibleTo<T, ranges::common_reference_t<T, U>> &&

ConvertibleTo<U, ranges::common_reference_t<T, U>>;

The concept CommonReference<T, U> specifies that two types T and U
share a common

reference type (as computed by ranges::common_reference_t) to which both can
be

converted.

CommonReference<T, U> is satisfied only if, given expressions t and u
such that

decltype((t)) is T and decltype((u)) is U,

* ranges::common_reference_t<T, U>(t) is equal to
ranges::common_reference_t<T,

U>(t) if and only if t is an equality-preserving expression; and

* ranges::common_reference_t<T, U>(u) is equal to
ranges::common_reference_t<T,

U>(u) if and only if u is an equality-preserving expression.

In other words, the conversion to the common reference type must not alter
the

equality-preservation property of the original expression.

Equality preservation

An expression is equality preserving if it results in equal outputs given
equal

inputs.

* The inputs to an expression consist of its operands.

* The outputs of an expression consist of its result and all operands
modified by

the expression (if any).

Every expression required to be equality preserving is further required to be

stable: two evaluations of such an expression with the same input objects
must have

equal outputs absent any explicit intervening modification of those input
objects.

# See also¶

common_reference determine the common reference type of a set of
types

*(class template)*

Common specifies that two types share a common type

(concept)

common_type determine the common type of a set of types

*(class template)*

2022.07.31 | http://cppreference.com |