cppdraft_translate/cppdraft/range/slide/view.md

[range.slide.view]

25 Ranges library [ranges]

25.7 Range adaptors [range.adaptors]

25.7.30 Slide view [range.slide]

25.7.30.2 Class template slide_view [range.slide.view]

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namespace std::ranges {templateconcept slide-caches-nothing = random_access_range && sized_range; // exposition onlytemplateconcept slide-caches-last = // exposition only && bidirectional_range && common_range; templateconcept slide-caches-first = // exposition only && ; template<forward_range V>requires viewclass slide_view : public view_interface<slide_view> { V base_; // exposition only range_difference_t n_; // exposition only// [range.slide.iterator], class template slide_view​::​iteratortemplate class iterator; // exposition only// [range.slide.sentinel], class slide_view​::​sentinelclass sentinel; // exposition onlypublic:constexpr explicit slide_view(V base, range_difference_t n); constexpr V base() const & requires copy_constructible { return base_; }constexpr V base() && { return std::move(base_); }constexpr auto begin()requires (!(simple-view && slide-caches-nothing)); constexpr auto begin() const requires slide-caches-nothing; constexpr auto end()requires (!(simple-view && slide-caches-nothing)); constexpr auto end() const requires slide-caches-nothing; constexpr auto size() requires sized_range; constexpr auto size() const requires sized_range; constexpr auto reserve_hintsize() requires approximately_sized_range; constexpr auto reserve_hintsize() const requires approximately_sized_range; }; template slide_view(R&&, range_difference_t) -> slide_view<views::all_t>;}

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constexpr explicit slide_view(V base, range_difference_t<V> n);

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Preconditions: n > 0 is true.

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Effects: Initializes base_ with std​::​move(base) andn_ with n.

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constexpr auto begin() requires (!([simple-view](range.utility.helpers#concept:simple-view "25.5.2 Helper concepts [range.utility.helpers]")<V> && [slide-caches-nothing](#concept:slide-caches-nothing "25.7.30.2 Class template slide_­view [range.slide.view]")<const V>));

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Returns:

• (3.1)

If V models slide-caches-first,iterator(ranges::begin(base_), ranges::next(ranges::begin(base_), n_ - 1, ranges::end(base_)), n_)

• (3.2)

Otherwise, iterator(ranges​::​begin(base_), n_).

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Remarks: In order to provide the amortized constant-time complexity required by the range concept, this function caches the result within the slide_view for use on subsequent calls when V models slide-caches-first.

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constexpr auto begin() const requires [slide-caches-nothing](#concept:slide-caches-nothing "25.7.30.2 Class template slide_­view [range.slide.view]")<const V>;

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Returns: iterator(ranges​::​begin(base_), n_).

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constexpr auto end() requires (!([simple-view](range.utility.helpers#concept:simple-view "25.5.2 Helper concepts [range.utility.helpers]")<V> && [slide-caches-nothing](#concept:slide-caches-nothing "25.7.30.2 Class template slide_­view [range.slide.view]")<const V>));

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Returns:

• (6.1)

If V models slide-caches-nothing,iterator(ranges::begin(base_) + range_difference_t(size()), n_)

• (6.2)

Otherwise, if V models slide-caches-last,iterator(ranges::prev(ranges::end(base_), n_ - 1, ranges::begin(base_)), n_)

• (6.3)

Otherwise, if V models common_range,iterator(ranges::end(base_), ranges::end(base_), n_)

• (6.4)

Otherwise, sentinel(ranges​::​end(base_)).

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Remarks: In order to provide the amortized constant-time complexity required by the range concept, this function caches the result within the slide_view for use on subsequent calls when V models slide-caches-last.

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constexpr auto end() const requires [slide-caches-nothing](#concept:slide-caches-nothing "25.7.30.2 Class template slide_­view [range.slide.view]")<const V>;

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Returns: begin() + range_difference_t(size()).

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constexpr auto size() requires [sized_range](range.sized#concept:sized_range "25.4.4 Sized ranges [range.sized]")<V>; constexpr auto size() const requires [sized_range](range.sized#concept:sized_range "25.4.4 Sized ranges [range.sized]")<const V>;

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Effects: Equivalent to:auto sz = ranges::distance(base_) - n_ + 1;if (sz < 0) sz = 0;return to-unsigned-like(sz);

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constexpr auto reserve_hint() requires [approximately_sized_range](range.approximately.sized#concept:approximately_sized_range "25.4.3 Approximately sized ranges [range.approximately.sized]")<V>; constexpr auto reserve_hint() const requires [approximately_sized_range](range.approximately.sized#concept:approximately_sized_range "25.4.3 Approximately sized ranges [range.approximately.sized]")<const V>;

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Effects: Equivalent to:auto sz = static_cast<range_difference_t<decltype((base_))>>(ranges::reserve_hint(base_)) -n_ + 1;if (sz < 0) sz = 0;return to-unsigned-like(sz);