synth-three-way, synth-three-way-result
constexpr auto synth-three-way = /* see below */; | (1) | (since C++20) (exposition only*) |
template< class T, class U = T >
using synth-three-way-result =
decltype(synth-three-way(std::declval<T&>(), std::declval<U&>()));
| (2) | (since C++20) (exposition only*) |
1) A function object whose
operator() behaves as the synthesized three-way comparison function. Equivalent to: constexpr auto synth-three-way =
[]<class T, class U>(const T& t, const U& u)
requires requires
{
{ t < u } -> boolean-testable;
{ u < t } -> boolean-testable;
}
{
if constexpr (std::three_way_comparable_with<T, U>)
return t <=> u;
else
{
if (t < u)
return std::weak_ordering::less;
if (u < t)
return std::weak_ordering::greater;
return std::weak_ordering::equivalent;
}
};
2) The return type of the
operator() of (1) (synth-three-way).Parameters
| t, u | - | the values to be compared |
Return value
The compare result.
See also
|
(removed in C++20)(removed in C++20)(removed in C++20)(removed in C++20)(removed in C++20)(C++20) | lexicographically compares the values in the pair (function template) |
|
(removed in C++20)(removed in C++20)(removed in C++20)(removed in C++20)(removed in C++20)(C++20) | lexicographically compares the values in the tuple (function template) |
|
(C++11)(C++11)(removed in C++20)(C++11)(removed in C++20)(C++11)(removed in C++20)(C++11)(removed in C++20)(C++11)(removed in C++20)(C++20) | lexicographically compares the values of two arrays (function template) |
|
(removed in C++20)(removed in C++20)(removed in C++20)(removed in C++20)(removed in C++20)(C++20) | lexicographically compares the values of two deques (function template) |
|
(C++11)(C++11)(removed in C++20)(C++11)(removed in C++20)(C++11)(removed in C++20)(C++11)(removed in C++20)(C++11)(removed in C++20)(C++20) | lexicographically compares the values of two forward_lists (function template) |
|
(removed in C++20)(removed in C++20)(removed in C++20)(removed in C++20)(removed in C++20)(C++20) | lexicographically compares the values of two lists (function template) |
|
(removed in C++20)(removed in C++20)(removed in C++20)(removed in C++20)(removed in C++20)(C++20) | lexicographically compares the values of two vectors (function template) |
|
(removed in C++20)(removed in C++20)(removed in C++20)(removed in C++20)(removed in C++20)(C++20) | lexicographically compares the values of two maps (function template) |
|
(removed in C++20)(removed in C++20)(removed in C++20)(removed in C++20)(removed in C++20)(C++20) | lexicographically compares the values of two multimaps (function template) |
|
(removed in C++20)(removed in C++20)(removed in C++20)(removed in C++20)(removed in C++20)(C++20) | lexicographically compares the values of two sets (function template) |
|
(removed in C++20)(removed in C++20)(removed in C++20)(removed in C++20)(removed in C++20)(C++20) | lexicographically compares the values of two multisets (function template) |
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