From Jason Turner

[pair.astuple]

C++17 → C++20 2.3 KB 33 lines
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Archived: C++17 | C++20
Markdown: C++17 | C++20
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  1. tmp/tmpnmncaqw1/{from.md → to.md} +14 -13
tmp/tmpnmncaqw1/{from.md → to.md} RENAMED
@@ -4,20 +4,19 @@
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  template<class T1, class T2>
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  struct tuple_size<pair<T1, T2>> : integral_constant<size_t, 2> { };
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  ```
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  ``` cpp
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- tuple_element<0, pair<T1, T2>>::type
 
 
 
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  ```
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- *Value:* The type `T1`.
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- ``` cpp
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- tuple_element<1, pair<T1, T2>>::type
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- ```
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-
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- *Value:* The type T2.
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  ``` cpp
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  template<size_t I, class T1, class T2>
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  constexpr tuple_element_t<I, pair<T1, T2>>& get(pair<T1, T2>& p) noexcept;
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  template<size_t I, class T1, class T2>
@@ -26,12 +25,16 @@ template<size_t I, class T1, class T2>
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  constexpr tuple_element_t<I, pair<T1, T2>>&& get(pair<T1, T2>&& p) noexcept;
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  template<size_t I, class T1, class T2>
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  constexpr const tuple_element_t<I, pair<T1, T2>>&& get(const pair<T1, T2>&& p) noexcept;
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  ```
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- *Returns:* If `I == 0` returns a reference to `p.first`; if `I == 1`
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- returns a reference to `p.second`; otherwise the program is ill-formed.
 
 
 
 
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  ``` cpp
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  template<class T1, class T2>
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  constexpr T1& get(pair<T1, T2>& p) noexcept;
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  template<class T1, class T2>
@@ -40,12 +43,11 @@ template <class T1, class T2>
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  constexpr T1&& get(pair<T1, T2>&& p) noexcept;
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  template<class T1, class T2>
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  constexpr const T1&& get(const pair<T1, T2>&& p) noexcept;
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  ```
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- *Requires:* `T1` and `T2` are distinct types. Otherwise, the program is
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- ill-formed.
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  *Returns:* A reference to `p.first`.
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  ``` cpp
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  template<class T2, class T1>
@@ -56,10 +58,9 @@ template <class T2, class T1>
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  constexpr T2&& get(pair<T1, T2>&& p) noexcept;
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  template<class T2, class T1>
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  constexpr const T2&& get(const pair<T1, T2>&& p) noexcept;
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  ```
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- *Requires:* `T1` and `T2` are distinct types. Otherwise, the program is
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- ill-formed.
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  *Returns:* A reference to `p.second`.
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  template<class T1, class T2>
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  struct tuple_size<pair<T1, T2>> : integral_constant<size_t, 2> { };
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  ```
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  ``` cpp
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+ template<size_t I, class T1, class T2>
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+ struct tuple_element<I, pair<T1, T2>> {
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+ using type = see below ;
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+ };
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  ```
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+ *Mandates:* `I` < 2.
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+ *Type:* The type `T1` if `I` is 0, otherwise the type `T2`.
 
 
 
 
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  ``` cpp
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  template<size_t I, class T1, class T2>
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  constexpr tuple_element_t<I, pair<T1, T2>>& get(pair<T1, T2>& p) noexcept;
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  template<size_t I, class T1, class T2>
 
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  constexpr tuple_element_t<I, pair<T1, T2>>&& get(pair<T1, T2>&& p) noexcept;
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  template<size_t I, class T1, class T2>
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  constexpr const tuple_element_t<I, pair<T1, T2>>&& get(const pair<T1, T2>&& p) noexcept;
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  ```
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+ *Mandates:* `I` < 2.
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+
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+ *Returns:*
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+
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+ - If `I` is 0, returns a reference to `p.first`.
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+ - If `I` is 1, returns a reference to `p.second`.
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  ``` cpp
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  template<class T1, class T2>
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  constexpr T1& get(pair<T1, T2>& p) noexcept;
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  template<class T1, class T2>
 
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  constexpr T1&& get(pair<T1, T2>&& p) noexcept;
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  template<class T1, class T2>
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  constexpr const T1&& get(const pair<T1, T2>&& p) noexcept;
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  ```
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+ *Mandates:* `T1` and `T2` are distinct types.
 
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  *Returns:* A reference to `p.first`.
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  ``` cpp
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  template<class T2, class T1>
 
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  constexpr T2&& get(pair<T1, T2>&& p) noexcept;
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  template<class T2, class T1>
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  constexpr const T2&& get(const pair<T1, T2>&& p) noexcept;
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  ```
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+ *Mandates:* `T1` and `T2` are distinct types.
 
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  *Returns:* A reference to `p.second`.
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