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Document reference specializations of variant_size, variant_alternative

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Peter Dimov
2019-02-22 02:07:47 +02:00
parent c1287f9e95
commit 4c8b0d2dee
1 changed files with 16 additions and 2 deletions
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18
doc/variant/reference.adoc
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@ -41,6 +41,9 @@ template<class T> struct variant_size<T const>: variant_size<T> {};
template<class T> struct variant_size<T volatile>: variant_size<T> {}; template<class T> struct variant_size<T volatile>: variant_size<T> {};
template<class T> struct variant_size<T const volatile>: variant_size<T> {}; template<class T> struct variant_size<T const volatile>: variant_size<T> {};
template<class T> struct variant_size<T&>: variant_size<T> {}; // extension
template<class T> struct variant_size<T&&>: variant_size<T> {}; // extension
template<class T> template<class T>
inline constexpr size_t variant_size_v = variant_size<T>::value; inline constexpr size_t variant_size_v = variant_size<T>::value;
@ -56,6 +59,9 @@ template<size_t I, class T> struct variant_alternative<I, T const>;
template<size_t I, class T> struct variant_alternative<I, T volatile>; template<size_t I, class T> struct variant_alternative<I, T volatile>;
template<size_t I, class T> struct variant_alternative<I, T const volatile>; template<size_t I, class T> struct variant_alternative<I, T const volatile>;
template<size_t I, class T> struct variant_alternative<I, T&>; // extension
template<size_t I, class T> struct variant_alternative<I, T&&>; // extension
template<size_t I, class T> template<size_t I, class T>
using variant_alternative_t = typename variant_alternative<I, T>::type; using variant_alternative_t = typename variant_alternative<I, T>::type;
@ -630,6 +636,12 @@ template<size_t I, class T> struct variant_alternative<I, T volatile>;
``` ```
template<size_t I, class T> struct variant_alternative<I, T const volatile>; template<size_t I, class T> struct variant_alternative<I, T const volatile>;
``` ```
```
template<size_t I, class T> struct variant_alternative<I, T&>; // extension
```
```
template<size_t I, class T> struct variant_alternative<I, T&&>; // extension
```
[none] [none]
* {blank} * {blank}
+ +
@ -639,8 +651,10 @@ If `typename variant_alternative<I, T>::type` exists and is `U`,
* `variant_alternative<I, T const>::type` is `U const`; * `variant_alternative<I, T const>::type` is `U const`;
* `variant_alternative<I, T volatile>::type` is `U volatile`; * `variant_alternative<I, T volatile>::type` is `U volatile`;
* `variant_alternative<I, T const volatile>::type` is `U const volatile`. * `variant_alternative<I, T const volatile>::type` is `U const volatile`.
* `variant_alternative<I, T&>::type` is `U&`.
* `variant_alternative<I, T&&>::type` is `U&&`.
Otherwise, the three structs have no `type` member. Otherwise, these structs have no member `type`.
-- --
``` ```
@ -651,7 +665,7 @@ template<size_t I, class... T>
* {blank} * {blank}
+ +
When `I < sizeof...(T)`, the nested type `type` is an alias for the `I`-th When `I < sizeof...(T)`, the nested type `type` is an alias for the `I`-th
(zero-based) type in `T...`. Otherwise, there is no `type` member. (zero-based) type in `T...`. Otherwise, there is no member `type`.
### holds_alternative ### holds_alternative