[range.take.view]

# 25 Ranges library [[ranges]](./#ranges)

## 25.7 Range adaptors [[range.adaptors]](range.adaptors#range.take.view)

### 25.7.10 Take view [[range.take]](range.take#view)

#### 25.7.10.2 Class template take_view [range.take.view]

[ð](#lib:take_view)

namespace std::ranges {template<[view](range.view#concept:view "25.4.5 Views [range.view]") V>class take_view : public view_interface<take_view<V>> {private: V *base_* = V(); // *exposition only* range_difference_t<V> *count_* = 0; // *exposition only*// [[range.take.sentinel]](range.take.sentinel "25.7.10.3 Class template take_­view​::​sentinel"), class template take_view​::​*sentinel*template<bool> class *sentinel*; // *exposition only*public: take_view() requires [default_initializable](concept.default.init#concept:default_initializable "18.4.12 Concept default_­initializable [concept.default.init]")<V> = default; constexpr explicit take_view(V base, range_difference_t<V> count); constexpr V base() const & requires [copy_constructible](concept.copyconstructible#concept:copy_constructible "18.4.14 Concept copy_­constructible [concept.copyconstructible]")<V> { return *base_*; }constexpr V base() && { return std::move(*base_*); }constexpr auto begin() requires (![*simple-view*](range.utility.helpers#concept:simple-view "25.5.2 Helper concepts [range.utility.helpers]")<V>) {if constexpr ([sized_range](range.sized#concept:sized_range "25.4.4 Sized ranges [range.sized]")<V>) {if constexpr ([random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<V>) {return ranges::begin(*base_*); } else {auto sz = range_difference_t<V>(size()); return counted_iterator(ranges::begin(*base_*), sz); }} else if constexpr ([sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8 Concept sized_­sentinel_­for [iterator.concept.sizedsentinel]")<sentinel_t<V>, iterator_t<V>>) {auto it = ranges::begin(*base_*); auto sz = std::min(*count_*, ranges::end(*base_*) - it); return counted_iterator(std::move(it), sz); } else {return counted_iterator(ranges::begin(*base_*), *count_*); }}constexpr auto begin() const requires [range](range.range#concept:range "25.4.2 Ranges [range.range]")<const V> {if constexpr ([sized_range](range.sized#concept:sized_range "25.4.4 Sized ranges [range.sized]")<const V>) {if constexpr ([random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<const V>) {return ranges::begin(*base_*); } else {auto sz = range_difference_t<const V>(size()); return counted_iterator(ranges::begin(*base_*), sz); }} else if constexpr ([sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8 Concept sized_­sentinel_­for [iterator.concept.sizedsentinel]")<sentinel_t<const V>, iterator_t<const V>>) {auto it = ranges::begin(*base_*); auto sz = std::min(*count_*, ranges::end(*base_*) - it); return counted_iterator(std::move(it), sz); } else {return counted_iterator(ranges::begin(*base_*), *count_*); }}constexpr auto end() requires (![*simple-view*](range.utility.helpers#concept:simple-view "25.5.2 Helper concepts [range.utility.helpers]")<V>) {if constexpr ([sized_range](range.sized#concept:sized_range "25.4.4 Sized ranges [range.sized]")<V>) {if constexpr ([random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<V>)return ranges::begin(*base_*) + range_difference_t<V>(size()); elsereturn default_sentinel; } else if constexpr ([sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8 Concept sized_­sentinel_­for [iterator.concept.sizedsentinel]")<sentinel_t<V>, iterator_t<V>>) {return default_sentinel; } else {return *sentinel*<false>{ranges::end(*base_*)}; }}constexpr auto end() const requires [range](range.range#concept:range "25.4.2 Ranges [range.range]")<const V> {if constexpr ([sized_range](range.sized#concept:sized_range "25.4.4 Sized ranges [range.sized]")<const V>) {if constexpr ([random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<const V>)return ranges::begin(*base_*) + range_difference_t<const V>(size()); elsereturn default_sentinel; } else if constexpr ([sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8 Concept sized_­sentinel_­for [iterator.concept.sizedsentinel]")<sentinel_t<const V>, iterator_t<const V>>) {return default_sentinel; } else {return *sentinel*<true>{ranges::end(*base_*)}; }}constexpr auto size() requires [sized_range](range.sized#concept:sized_range "25.4.4 Sized ranges [range.sized]")<V> {auto n = ranges::size(*base_*); return ranges::min(n, static_cast<decltype(n)>(*count_*)); }constexpr auto size() const requires [sized_range](range.sized#concept:sized_range "25.4.4 Sized ranges [range.sized]")<const V> {auto n = ranges::size(*base_*); return ranges::min(n, static_cast<decltype(n)>(*count_*)); }constexpr auto reserve_hint() {if constexpr ([approximately_sized_range](range.approximately.sized#concept:approximately_sized_range "25.4.3 Approximately sized ranges [range.approximately.sized]")<V>) {auto n = static_cast<range_difference_t<V>>(ranges::reserve_hint(*base_*)); return *to-unsigned-like*(ranges::min(n, *count_*)); }return *to-unsigned-like*(*count_*); }constexpr auto reserve_hint() const {if constexpr ([approximately_sized_range](range.approximately.sized#concept:approximately_sized_range "25.4.3 Approximately sized ranges [range.approximately.sized]")<const V>) {auto n = static_cast<range_difference_t<const V>>(ranges::reserve_hint(*base_*)); return *to-unsigned-like*(ranges::min(n, *count_*)); }return *to-unsigned-like*(*count_*); }}; template<class R> take_view(R&&, range_difference_t<R>)-> take_view<views::all_t<R>>;}

[ð](#lib:take_view,constructor)

`constexpr explicit take_view(V base, range_difference_t<V> count);
`

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L6071)

*Preconditions*: count >= 0 is true[.](#1.sentence-1)

[2](#2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L6075)

*Effects*: Initializes *base_* with std​::​move(base) and*count_* with count[.](#2.sentence-1)
