tmp/tmpt1l22jj2/{from.md → to.md}
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| 1 |
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#### Class template `elements_view` <a id="range.elements.view">[[range.elements.view]]</a>
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``` cpp
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namespace std::ranges {
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template<class T, size_t N>
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concept has-tuple-element = // exposition only
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requires(T t) {
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typename tuple_size<T>::type;
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requires N < tuple_size_v<T>;
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typename tuple_element_t<N, T>;
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{ get<N>(t) } -> convertible_to<const tuple_element_t<N, T>&>;
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};
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template<input_range V, size_t N>
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requires view<V> && has-tuple-element<range_value_t<V>, N> &&
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has-tuple-element<remove_reference_t<range_reference_t<V>>, N>
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class elements_view : public view_interface<elements_view<V, N>> {
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public:
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elements_view() = default;
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constexpr explicit elements_view(V base);
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constexpr V base() const& requires copy_constructible<V> { return base_; }
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constexpr V base() && { return std::move(base_); }
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constexpr auto begin() requires (!simple-view<V>)
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{ return iterator<false>(ranges::begin(base_)); }
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constexpr auto begin() const requires simple-view<V>
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{ return iterator<true>(ranges::begin(base_)); }
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constexpr auto end()
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{ return sentinel<false>{ranges::end(base_)}; }
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constexpr auto end() requires common_range<V>
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{ return iterator<false>{ranges::end(base_)}; }
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constexpr auto end() const requires range<const V>
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{ return sentinel<true>{ranges::end(base_)}; }
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constexpr auto end() const requires common_range<const V>
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{ return iterator<true>{ranges::end(base_)}; }
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constexpr auto size() requires sized_range<V>
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{ return ranges::size(base_); }
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constexpr auto size() const requires sized_range<const V>
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{ return ranges::size(base_); }
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private:
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// [range.elements.iterator], class template elements_view::iterator
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template<bool> struct iterator; // exposition only
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// [range.elements.sentinel], class template elements_view::sentinel
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template<bool> struct sentinel; // exposition only
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V base_ = V(); // exposition only
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};
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}
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```
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``` cpp
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constexpr explicit elements_view(V base);
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```
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*Effects:* Initializes *base\_* with `std::move(base)`.
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