depish/cppdraft_translate
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity
Files
main
cppdraft_translate/cppdraft/range/repeat.md
Leonov Artur (Depish) 043225d523 Init
2025-10-25 03:02:53 +03:00

329 lines
16 KiB
Markdown
Raw Permalink Blame History

This file contains invisible Unicode characters

This file contains invisible Unicode characters that are indistinguishable to humans but may be processed differently by a computer. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

[range.repeat]
# 25 Ranges library [[ranges]](./#ranges)
## 25.6 Range factories [[range.factories]](range.factories#range.repeat)
### 25.6.5 Repeat view [range.repeat]
#### [25.6.5.1](#overview) Overview [[range.repeat.overview]](range.repeat.overview)
[1](#overview-1)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L3559)
repeat_view generates a sequence of elements
by repeatedly producing the same value[.](#overview-1.sentence-1)
[2](#overview-2)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L3563)
The name views​::​repeat denotes
a customization point object ([[customization.point.object]](customization.point.object "16.3.3.3.5 Customization Point Object types"))[.](#overview-2.sentence-1)
Given subexpressions E and F,
the expressions views​::​repeat(E) and views​::​repeat(E, F) are expression-equivalent torepeat_view<decay_t<decltype((E))>>(E) and repeat_view(E, F), respectively[.](#overview-2.sentence-2)
[3](#overview-3)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L3572)
[*Example [1](#overview-example-1)*: for (int i : views::repeat(17, 4)) cout << i << ' ';// prints 17 17 17 17 — *end example*]
#### [25.6.5.2](#view) Class template repeat_view [[range.repeat.view]](range.repeat.view)
namespace std::ranges {template<class T>concept [*integer-like-with-usable-difference-type*](#concept:integer-like-with-usable-difference-type "25.6.5.2 Class template repeat_­view [range.repeat.view]") = // *exposition only**is-signed-integer-like*<T> || (*is-integer-like*<T> && [weakly_incrementable](iterator.concept.winc#concept:weakly_incrementable "24.3.4.4 Concept weakly_­incrementable [iterator.concept.winc]")<T>); template<[move_constructible](concept.moveconstructible#concept:move_constructible "18.4.13 Concept move_­constructible [concept.moveconstructible]") T, [semiregular](concepts.object#concept:semiregular "18.6 Object concepts [concepts.object]") Bound = unreachable_sentinel_t>requires (is_object_v<T> && [same_as](concept.same#concept:same_as "18.4.2 Concept same_­as [concept.same]")<T, remove_cv_t<T>> &&([*integer-like-with-usable-difference-type*](#concept:integer-like-with-usable-difference-type "25.6.5.2 Class template repeat_­view [range.repeat.view]")<Bound> ||[same_as](concept.same#concept:same_as "18.4.2 Concept same_­as [concept.same]")<Bound, unreachable_sentinel_t>))class [repeat_view](#lib:repeat_view "25.6.5.2 Class template repeat_­view [range.repeat.view]") : public view_interface<repeat_view<T, Bound>> {private:// [[range.repeat.iterator]](#iterator "25.6.5.3 Class repeat_­view​::​iterator"), class repeat_view​::​*iterator*struct *iterator*; // *exposition only**movable-box*<T> *value_*; // *exposition only*, see [[range.move.wrap]](range.move.wrap "25.7.3 Movable wrapper") Bound *bound_* = Bound(); // *exposition only*public: repeat_view() requires [default_initializable](concept.default.init#concept:default_initializable "18.4.12 Concept default_­initializable [concept.default.init]")<T> = default; constexpr explicit repeat_view(const T& value, Bound bound = Bound())requires [copy_constructible](concept.copyconstructible#concept:copy_constructible "18.4.14 Concept copy_­constructible [concept.copyconstructible]")<T>; constexpr explicit repeat_view(T&& value, Bound bound = Bound()); template<class... TArgs, class... BoundArgs>requires [constructible_from](concept.constructible#concept:constructible_from "18.4.11 Concept constructible_­from [concept.constructible]")<T, TArgs...> &&[constructible_from](concept.constructible#concept:constructible_from "18.4.11 Concept constructible_­from [concept.constructible]")<Bound, BoundArgs...>constexpr explicit repeat_view(piecewise_construct_t,
tuple<TArgs...> value_args, tuple<BoundArgs...> bound_args = tuple<>{}); constexpr *iterator* begin() const; constexpr *iterator* end() const requires (![same_as](concept.same#concept:same_as "18.4.2 Concept same_­as [concept.same]")<Bound, unreachable_sentinel_t>); constexpr unreachable_sentinel_t end() const noexcept; constexpr auto size() const requires (![same_as](concept.same#concept:same_as "18.4.2 Concept same_­as [concept.same]")<Bound, unreachable_sentinel_t>); }; template<class T, class Bound = unreachable_sentinel_t> repeat_view(T, Bound = Bound()) -> repeat_view<T, Bound>;}
[🔗](#lib:repeat_view,constructor)
`constexpr explicit repeat_view(const T& value, Bound bound = Bound())
requires [copy_constructible](concept.copyconstructible#concept:copy_constructible "18.4.14 Concept copy_­constructible [concept.copyconstructible]")<T>;
`
[1](#view-1)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L3632)
*Preconditions*: If Bound is not unreachable_sentinel_t,bound ≥ 0[.](#view-1.sentence-1)
[2](#view-2)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L3637)
*Effects*: Initializes *value_* with value and*bound_* with bound[.](#view-2.sentence-1)
[🔗](#lib:repeat_view,constructor_)
`constexpr explicit repeat_view(T&& value, Bound bound = Bound());
`
[3](#view-3)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L3649)
*Preconditions*: If Bound is not unreachable_sentinel_t, bound ≥ 0[.](#view-3.sentence-1)
[4](#view-4)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L3653)
*Effects*: Initializes *value_* with std​::​move(value) and*bound_* with bound[.](#view-4.sentence-1)
[🔗](#lib:repeat_view,constructor__)
`template<class... TArgs, class... BoundArgs>
requires [constructible_from](concept.constructible#concept:constructible_from "18.4.11 Concept constructible_­from [concept.constructible]")<T, TArgs...> &&
[constructible_from](concept.constructible#concept:constructible_from "18.4.11 Concept constructible_­from [concept.constructible]")<Bound, BoundArgs...>
constexpr explicit repeat_view(piecewise_construct_t,
tuple<TArgs...> value_args, tuple<BoundArgs...> bound_args = tuple<>{});
`
[5](#view-5)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L3669)
*Effects*: Initializes *value_* withmake_from_tuple<T>(std​::​move(value_args)) and
initializes *bound_* withmake_from_tuple<Bound>(std​::​move(bound_args))[.](#view-5.sentence-1)
The behavior is undefined ifBound is not unreachable_sentinel_t and*bound_* is negative[.](#view-5.sentence-2)
[🔗](#lib:begin,repeat_view)
`constexpr iterator begin() const;
`
[6](#view-6)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L3687)
*Effects*: Equivalent to: return *iterator*(addressof(**value_*));
[🔗](#lib:end,repeat_view)
`constexpr iterator end() const requires (![same_as](concept.same#concept:same_as "18.4.2 Concept same_­as [concept.same]")<Bound, unreachable_sentinel_t>);
`
[7](#view-7)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L3698)
*Effects*: Equivalent to: return *iterator*(addressof(**value_*), *bound_*);
[🔗](#lib:end,repeat_view_)
`constexpr unreachable_sentinel_t end() const noexcept;
`
[8](#view-8)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L3709)
*Effects*: Equivalent to: return unreachable_sentinel;
[🔗](#lib:size,repeat_view)
`constexpr auto size() const requires (![same_as](concept.same#concept:same_as "18.4.2 Concept same_­as [concept.same]")<Bound, unreachable_sentinel_t>);
`
[9](#view-9)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L3720)
*Effects*: Equivalent to: return *to-unsigned-like*(*bound_*);
#### [25.6.5.3](#iterator) Class repeat_view​::​*iterator* [[range.repeat.iterator]](range.repeat.iterator)
[🔗](#lib:repeat_view::iterator)
namespace std::ranges {template<[move_constructible](concept.moveconstructible#concept:move_constructible "18.4.13 Concept move_­constructible [concept.moveconstructible]") T, [semiregular](concepts.object#concept:semiregular "18.6 Object concepts [concepts.object]") Bound>requires (is_object_v<T> && [same_as](concept.same#concept:same_as "18.4.2 Concept same_­as [concept.same]")<T, remove_cv_t<T>> &&([*integer-like-with-usable-difference-type*](#concept:integer-like-with-usable-difference-type "25.6.5.2 Class template repeat_­view [range.repeat.view]")<Bound> ||[same_as](concept.same#concept:same_as "18.4.2 Concept same_­as [concept.same]")<Bound, unreachable_sentinel_t>))class repeat_view<T, Bound>::*iterator* {private:using *index-type* = // *exposition only* conditional_t<[same_as](concept.same#concept:same_as "18.4.2 Concept same_­as [concept.same]")<Bound, unreachable_sentinel_t>, ptrdiff_t, Bound>; const T* *value_* = nullptr; // *exposition only**index-type* *current_* = *index-type*(); // *exposition only*constexpr explicit *iterator*(const T* value, *index-type* b = *index-type*()); // *exposition only*public:using iterator_concept = random_access_iterator_tag; using iterator_category = random_access_iterator_tag; using value_type = T; using difference_type = *see below*; *iterator*() = default; constexpr const T& operator*() const noexcept; constexpr *iterator*& operator++(); constexpr *iterator* operator++(int); constexpr *iterator*& operator--(); constexpr *iterator* operator--(int); constexpr *iterator*& operator+=(difference_type n); constexpr *iterator*& operator-=(difference_type n); constexpr const T& operator[](difference_type n) const noexcept; friend constexpr bool operator==(const *iterator*& x, const *iterator*& y); friend constexpr auto operator<=>(const *iterator*& x, const *iterator*& y); friend constexpr *iterator* operator+(*iterator* i, difference_type n); friend constexpr *iterator* operator+(difference_type n, *iterator* i); friend constexpr *iterator* operator-(*iterator* i, difference_type n); friend constexpr difference_type operator-(const *iterator*& x, const *iterator*& y); };}
[1](#iterator-1)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L3775)
If *is-signed-integer-like*<*index-type*> is true,
the member [*typedef-name*](dcl.typedef#nt:typedef-name "9.2.4 The typedef specifier [dcl.typedef]") difference_type denotes *index-type*[.](#iterator-1.sentence-1)
Otherwise, it denotes *IOTA-DIFF-T*(*index-type*) ([[range.iota.view]](range.iota.view "25.6.4.2 Class template iota_­view"))[.](#iterator-1.sentence-2)
[🔗](#lib:repeat_view::iterator,constructor)
`constexpr explicit iterator(const T* value, index-type b = index-type());
`
[2](#iterator-2)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L3787)
*Preconditions*: If Bound is not unreachable_sentinel_t, b ≥ 0[.](#iterator-2.sentence-1)
[3](#iterator-3)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L3791)
*Effects*: Initializes *value_* with value and*current_* with b[.](#iterator-3.sentence-1)
[🔗](#lib:operator*,repeat_view::iterator)
`constexpr const T& operator*() const noexcept;
`
[4](#iterator-4)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L3803)
*Effects*: Equivalent to: return **value_*;
[🔗](#lib:operator++,repeat_view::iterator)
`constexpr iterator& operator++();
`
[5](#iterator-5)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L3814)
*Effects*: Equivalent to:++*current_*;return *this;
[🔗](#lib:operator++,repeat_view::iterator_)
`constexpr iterator operator++(int);
`
[6](#iterator-6)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L3829)
*Effects*: Equivalent to:auto tmp = *this;++*this;return tmp;
[🔗](#lib:operator--,repeat_view::iterator)
`constexpr iterator& operator--();
`
[7](#iterator-7)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L3845)
*Preconditions*: If Bound is not unreachable_sentinel_t,current_>0[.](#iterator-7.sentence-1)
[8](#iterator-8)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L3850)
*Effects*: Equivalent to:--*current_*;return *this;
[🔗](#lib:operator--,repeat_view::iterator_)
`constexpr iterator operator--(int);
`
[9](#iterator-9)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L3865)
*Effects*: Equivalent to:auto tmp = *this;--*this;return tmp;
[🔗](#lib:operator+=,repeat_view::iterator)
`constexpr iterator& operator+=(difference_type n);
`
[10](#iterator-10)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L3881)
*Preconditions*: If Bound is not unreachable_sentinel_t,current_+n≥0[.](#iterator-10.sentence-1)
[11](#iterator-11)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L3886)
*Effects*: Equivalent to:*current_* += n;return *this;
[🔗](#lib:operator-=,repeat_view::iterator)
`constexpr iterator& operator-=(difference_type n);
`
[12](#iterator-12)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L3901)
*Preconditions*: If Bound is not unreachable_sentinel_t,current_−n≥0[.](#iterator-12.sentence-1)
[13](#iterator-13)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L3906)
*Effects*: Equivalent to:*current_* -= n;return *this;
[🔗](#lib:operator%5b%5d,repeat_view::iterator)
`constexpr const T& operator[](difference_type n) const noexcept;
`
[14](#iterator-14)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L3921)
*Effects*: Equivalent to: return *(*this + n);
[🔗](#lib:operator==,repeat_view::iterator)
`friend constexpr bool operator==(const iterator& x, const iterator& y);
`
[15](#iterator-15)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L3932)
*Effects*: Equivalent to: return x.*current_* == y.*current_*;
[🔗](#lib:operator%3c=%3e,repeat_view::iterator)
`friend constexpr auto operator<=>(const iterator& x, const iterator& y);
`
[16](#iterator-16)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L3943)
*Effects*: Equivalent to: return x.*current_* <=> y.*current_*;
[🔗](#lib:operator+,repeat_view::iterator)
`friend constexpr iterator operator+(iterator i, difference_type n);
friend constexpr iterator operator+(difference_type n, iterator i);
`
[17](#iterator-17)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L3955)
*Effects*: Equivalent to:i += n;return i;
[🔗](#lib:operator-,repeat_view::iterator)
`friend constexpr iterator operator-(iterator i, difference_type n);
`
[18](#iterator-18)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L3970)
*Effects*: Equivalent to:i -= n;return i;
[🔗](#lib:operator-,repeat_view::iterator_)
`friend constexpr difference_type operator-(const iterator& x, const iterator& y);
`
[19](#iterator-19)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L3985)
*Effects*: Equivalent to:return static_cast<difference_type>(x.*current_*) - static_cast<difference_type>(y.*current_*);
Reference in New Issue View Git Blame Copy Permalink