tmp/tmpk2n3eyxc/{from.md → to.md}
RENAMED
|
@@ -0,0 +1,34 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
#### Exposition-only functions <a id="expos.only.func">[[expos.only.func]]</a>
|
| 2 |
+
|
| 3 |
+
Several function templates defined in [[support]] through [[thread]] and
|
| 4 |
+
[[depr]] are only defined for the purpose of exposition. The declaration
|
| 5 |
+
of such a function is followed by a comment ending in *exposition only*.
|
| 6 |
+
|
| 7 |
+
The following are defined for exposition only to aid in the
|
| 8 |
+
specification of the library:
|
| 9 |
+
|
| 10 |
+
``` cpp
|
| 11 |
+
template<class T> constexpr decay_t<T> decay-copy(T&& v)
|
| 12 |
+
noexcept(is_nothrow_convertible_v<T, decay_t<T>>) // exposition only
|
| 13 |
+
{ return std::forward<T>(v); }
|
| 14 |
+
|
| 15 |
+
constexpr auto synth-three-way =
|
| 16 |
+
[]<class T, class U>(const T& t, const U& u)
|
| 17 |
+
requires requires {
|
| 18 |
+
{ t < u } -> boolean-testable;
|
| 19 |
+
{ u < t } -> boolean-testable;
|
| 20 |
+
}
|
| 21 |
+
{
|
| 22 |
+
if constexpr (three_way_comparable_with<T, U>) {
|
| 23 |
+
return t <=> u;
|
| 24 |
+
} else {
|
| 25 |
+
if (t < u) return weak_ordering::less;
|
| 26 |
+
if (u < t) return weak_ordering::greater;
|
| 27 |
+
return weak_ordering::equivalent;
|
| 28 |
+
}
|
| 29 |
+
};
|
| 30 |
+
|
| 31 |
+
template<class T, class U=T>
|
| 32 |
+
using synth-three-way-result = decltype(synth-three-way(declval<T&>(), declval<U&>()));
|
| 33 |
+
```
|
| 34 |
+
|