tmp/tmp07tcn23m/{from.md → to.md}
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| 1 |
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### Single view <a id="range.single">[[range.single]]</a>
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#### Overview <a id="range.single.overview">[[range.single.overview]]</a>
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`single_view` produces a `view` that contains exactly one element of a
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specified value.
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The name `views::single` denotes a customization point object
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[[customization.point.object]]. Given a subexpression `E`, the
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expression `views::single(E)` is expression-equivalent to
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`single_view{E}`.
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[*Example 1*:
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``` cpp
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single_view s{4};
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for (int i : s)
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cout << i; // prints 4
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```
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— *end example*]
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#### Class template `single_view` <a id="range.single.view">[[range.single.view]]</a>
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``` cpp
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namespace std::ranges {
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template<copy_constructible T>
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requires is_object_v<T>
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class single_view : public view_interface<single_view<T>> {
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private:
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semiregular-box<T> value_; // exposition only{} (see [range.semi.wrap])
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public:
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single_view() = default;
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constexpr explicit single_view(const T& t);
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constexpr explicit single_view(T&& t);
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template<class... Args>
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requires constructible_from<T, Args...>
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constexpr single_view(in_place_t, Args&&... args);
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constexpr T* begin() noexcept;
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constexpr const T* begin() const noexcept;
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constexpr T* end() noexcept;
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constexpr const T* end() const noexcept;
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static constexpr size_t size() noexcept;
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constexpr T* data() noexcept;
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constexpr const T* data() const noexcept;
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};
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}
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```
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``` cpp
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constexpr explicit single_view(const T& t);
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```
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*Effects:* Initializes *value\_* with `t`.
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``` cpp
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constexpr explicit single_view(T&& t);
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```
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*Effects:* Initializes *value\_* with `std::move(t)`.
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``` cpp
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template<class... Args>
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constexpr single_view(in_place_t, Args&&... args);
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```
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*Effects:* Initializes *value\_* as if by
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*`value_`*`{in_place, std::forward<Args>(args)...}`.
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``` cpp
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constexpr T* begin() noexcept;
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constexpr const T* begin() const noexcept;
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```
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*Effects:* Equivalent to: `return data();`
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``` cpp
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constexpr T* end() noexcept;
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constexpr const T* end() const noexcept;
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```
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*Effects:* Equivalent to: `return data() + 1;`
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``` cpp
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static constexpr size_t size() noexcept;
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```
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*Effects:* Equivalent to: `return 1;`
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``` cpp
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constexpr T* data() noexcept;
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constexpr const T* data() const noexcept;
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```
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*Effects:* Equivalent to: `return `*`value_`*`.operator->();`
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