[range.istream] (original) (raw)
25 Ranges library [ranges]
25.6 Range factories [range.factories]
25.6.6 Istream view [range.istream]
25.6.6.1 Overview [range.istream.overview]
basic_istream_view models input_range and reads (using operator>>) successive elements from its corresponding input stream.
Given a type T and a subexpression E of type U, if U modelsderived_from<basic_istream<typename U::char_type,typename U::traits_type>>, then the expression views::istream<T>(E) is expression-equivalent tobasic_istream_view<T, typename U::char_type,typename U::traits_type>(E); otherwise, views::istream<T>(E) is ill-formed.
[Example 1: auto ints = istringstream{"0 1 2 3 4"}; ranges::copy(views::istream<int>(ints), ostream_iterator<int>{cout, "-"}); — _end example_]
25.6.6.2 Class template basic_istream_view [range.istream.view]
namespace std::ranges { template<class Val, class CharT, class Traits> concept stream-extractable = requires(basic_istream<CharT, Traits>& is, Val& t) { is >> t;};template<movable Val, class CharT, class Traits = char_traits<CharT>> requires default_initializable<Val> && <Val, CharT, Traits> class basic_istream_view : public view_interface<basic_istream_view<Val, CharT, Traits>> { public: constexpr explicit basic_istream_view(basic_istream<CharT, Traits>& stream);constexpr auto begin() { *stream_ >> value_;return iterator{*this};} constexpr default_sentinel_t end() const noexcept;private: struct iterator; basic_istream<CharT, Traits>* stream_; Val value_ = Val(); };}
constexpr explicit basic_istream_view(basic_istream<CharT, Traits>& stream);
Effects: Initializes stream_ with addressof(stream).
constexpr default_sentinel_t end() const noexcept;
Effects: Equivalent to: return default_sentinel;
25.6.6.3 Class basic_istream_view::iterator [range.istream.iterator]
namespace std::ranges { template<movable Val, class CharT, class Traits> requires default_initializable<Val> && <Val, CharT, Traits> class basic_istream_view<Val, CharT, Traits>::iterator { public: using iterator_concept = input_iterator_tag;using difference_type = ptrdiff_t;using value_type = Val;constexpr explicit iterator(basic_istream_view& parent) noexcept;iterator(const iterator&) = delete;iterator(iterator&&) = default;iterator& operator=(const iterator&) = delete;iterator& operator=(iterator&&) = default;iterator& operator++();void operator++(int); Val& operator*() const;friend bool operator==(const iterator& x, default_sentinel_t);private: basic_istream_view* parent_; };}
constexpr explicit _iterator_(basic_istream_view& parent) noexcept;
Effects: Initializes parent_ with addressof(parent).
Effects: Equivalent to:*_parent__->stream_ >> _parent__->value_;return *this;
Effects: Equivalent to ++*this.
Effects: Equivalent to: return _parent__->value_;
friend bool operator==(const _iterator_& x, default_sentinel_t);
Effects: Equivalent to: return !*x._parent__->stream_;