cppdraft_translate/cppdraft/range/to/input.md

[range.to.input]

25 Ranges library [ranges]

25.7 Range adaptors [range.adaptors]

25.7.35 To input view [range.to.input]

25.7.35.1 Overview [range.to.input.overview]

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to_input_view presents a view of an underlying sequence as an input-only non-common range.

[Note 1:

This is useful to avoid overhead that can be necessary to provide support for the operations needed for greater iterator strength.

— end note]

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The name views​::​to_input denotes a range adaptor object ([range.adaptor.object]).

Let E be an expression and let T be decltype((E)).

The expression views​::​to_input(E) is expression-equivalent to:

• (2.1)

  views​::​all(E) if T models input_range, does not satisfy common_range, and does not satisfy forward_range.

• (2.2)

  Otherwise, to_input_view(E).

25.7.35.2 Class template to_input_view [range.to.input.view]

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namespace std::ranges {template<input_range V>requires viewclass to_input_view : public view_interface<to_input_view> { V base_ = V(); // exposition only// [range.to.input.iterator], class template to_input_view​::​iteratortemplate class iterator; // exposition onlypublic: to_input_view() requires default_initializable = default; constexpr explicit to_input_view(V base); constexpr V base() const & requires copy_constructible { return base_; }constexpr V base() && { return std::move(base_); }constexpr auto begin() requires (); constexpr auto begin() const requires range; constexpr auto end() requires (); constexpr auto end() const requires range; constexpr auto size() requires sized_range; constexpr auto size() const requires sized_range; constexpr auto reserve_hint() requires approximately_sized_range; constexpr auto reserve_hint() const requires approximately_sized_range; }; template to_input_view(R&&) -> to_input_view<views::all_t>;}

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constexpr explicit to_input_view(V base);

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

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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>);

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Effects: Equivalent to: return iterator(ranges​::​begin(base_));

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constexpr auto begin() const requires [range](range.range#concept:range "25.4.2 Ranges [range.range]")<const V>;

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Effects: Equivalent to: return iterator(ranges​::​begin(base_));

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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>); constexpr auto end() const requires [range](range.range#concept:range "25.4.2 Ranges [range.range]")<const V>;

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Effects: Equivalent to: return ranges​::​end(base_);

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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: return ranges​::​size(base_);

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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: return ranges​::​reserve_hint(base_);

25.7.35.3 Class template to_input_view​::​iterator [range.to.input.iterator]

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namespace std::ranges {template<input_range V>requires viewtemplateclass to_input_view::iterator {using Base = maybe-const<Const, V>; // exposition only iterator_t<Base> current_ = iterator_t<Base>(); // exposition onlyconstexpr explicit iterator(iterator_t<Base> current); // exposition onlypublic:using difference_type = range_difference_t<Base>; using value_type = range_value_t<Base>; using iterator_concept = input_iterator_tag; iterator() requires default_initializable<iterator_t<Base>> = default; iterator(iterator&&) = default; iterator& operator=(iterator&&) = default; constexpr iterator(iterator i)requires Const && convertible_to<iterator_t, iterator_t<Base>>; constexpr iterator_t<Base> base() &&; constexpr const iterator_t<Base>& base() const & noexcept; constexpr decltype(auto) operator*() const { return **current_*; }constexpr iterator& operator++(); constexpr void operator++(int); friend constexpr bool operator==(const iterator& x, const sentinel_t<Base>& y); friend constexpr difference_type operator-(const sentinel_t<Base>& y, const iterator& x)requires sized_sentinel_for<sentinel_t<Base>, iterator_t<Base>>; friend constexpr difference_type operator-(const iterator& x, const sentinel_t<Base>& y)requires sized_sentinel_for<sentinel_t<Base>, iterator_t<Base>>; friend constexpr range_rvalue_reference_t<Base> iter_move(const iterator& i)noexcept(noexcept(ranges::iter_move(i.current_))); friend constexpr void iter_swap(const iterator& x, const iterator& y)noexcept(noexcept(ranges::iter_swap(x.current_, y.current_)))requires indirectly_swappable<iterator_t<Base>>; };}

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constexpr explicit iterator(iterator_t<Base> current);

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Effects: Initializes current_ with std​::​move(current).

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constexpr iterator(iterator<!Const> i) requires Const && [convertible_to](concept.convertible#concept:convertible_to "18.4.4 Concept convertible_­to [concept.convertible]")<iterator_t<V>, iterator_t<Base>>;

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Effects: Initializes current_ with std​::​move(i.current_).

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constexpr iterator_t<Base> base() &&;

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Returns: std​::​move(current_).

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constexpr const iterator_t<Base>& base() const & noexcept;

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Returns: current_.

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constexpr iterator& operator++();

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Effects: Equivalent to:++current_;return *this;

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constexpr void operator++(int);

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Effects: Equivalent to: ++*this;

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friend constexpr bool operator==(const iterator& x, const sentinel_t<Base>& y);

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Returns: x.current_ == y.

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friend constexpr difference_type operator-(const sentinel_t<Base>& y, const iterator& x) requires [sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8 Concept sized_­sentinel_­for [iterator.concept.sizedsentinel]")<sentinel_t<Base>, iterator_t<Base>>;

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Returns: y - x.current_.

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friend constexpr difference_type operator-(const iterator& x, const sentinel_t<Base>& y) requires [sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8 Concept sized_­sentinel_­for [iterator.concept.sizedsentinel]")<sentinel_t<Base>, iterator_t<Base>>;

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Returns: x.current_ - y.

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friend constexpr range_rvalue_reference_t<Base> iter_move(const iterator& i) noexcept(noexcept(ranges::iter_move(i.current_)));

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Effects: Equivalent to: return ranges​::​iter_move(i.current_);

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friend constexpr void iter_swap(const iterator& x, const iterator& y) noexcept(noexcept(ranges::iter_swap(x.current_, y.current_))) requires [indirectly_swappable](alg.req.ind.swap#concept:indirectly_swappable "24.3.7.4 Concept indirectly_­swappable [alg.req.ind.swap]")<iterator_t<Base>>;

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Effects: Equivalent to: ranges​::​iter_swap(x.current_, y.current_);