std::ranges::views::istream,std::ranges::basic_istream_view,std::ranges::istream_view,(3)

NAME
std::ranges::views::istream,std::ranges::basic_istream_view,std::ranges::istream_view, - std::ranges::views::istream,std::ranges::basic_istream_view,std::ranges::istream_view,

Synopsis
   Defined in header <ranges>
   template< std::movable Val, class CharT, class Traits =
   std::char_traits<CharT> >
       requires std::default_initializable<Val> &&
                /*stream-extractable*/<Val,CharT,Traits> (1) (since C++20)
   class basic_istream_view
       : public
   ranges::view_interface<basic_istream_view<Val,CharT,Traits>>
   Helper templates
   template< class Val > (2) (since C++20)
   using istream_view = ranges::basic_istream_view<Val, char>;
   template< class Val > (3) (since C++20)
   using wistream_view = ranges::basic_istream_view<Val, wchar_t>;
   Customization point objects
   namespace views {
       template< class T > (4) (since C++20)
       inline constexpr /*unspecified*/ istream = /*unspecified*/;
   }
   Helper concepts
   template< class Val, class CharT, class Traits >
   concept /*stream-extractable*/ = (exposition
       requires(std::basic_istream<CharT,Traits>& is, Val& t) { (5) only*)
           is >> t;
       };
   1) A range factory that generates a sequence of elements by repeatedly calling
   operator>>.
   2,3) Convenience alias templates for character types char and wchar_t.
   4) views::istream<T>(e) is expression-equivalent to (has the same effect as)
   ranges::basic_istream_view<T, typename U::char_type, typename U::traits_type>(e) for
   any suitable subexpressions e, where U is std::remove_reference_t<decltype(e)>. The
   program is ill-formed if U is not both publicly and unambiguously derived from
   std::basic_istream<typename U::char_type, typename U::traits_type>, which may result
   in a substitution failure.
   5) The exposition-only concept /*stream-extractable*/<Val,CharT,Traits> is satisfied
   when lvalue of Val can be extracted from lvalue of std::basic_istream<CharT,Traits>.
   The iterator type of basic_istream_view is move-only: it does not meet the
   LegacyIterator requirements, and thus does not work with pre-C++20 algorithms.

Member functions
   constructor constructs a basic_istream_view
                 (public member function)
   begin returns an iterator
                 (public member function)
   end returns std::default_sentinel
                 (public member function)
         Inherited from std::ranges::view_interface
                 although basic_istream_view is derived from
   (none) std::ranges::view_interface, it cannot use any of inherited member
                 functions. std::ranges::basic_istream_view::basic_istream_view
   constexpr explicit (since C++20)
       basic_istream_view( std::basic_istream<CharT, Traits>& stream );
   Initializes the stored pointer to stream with std::addressof(stream), and
   value-initializes the stored value of Val. std::ranges::basic_istream_view::begin
   constexpr auto begin(); (since C++20)
   Equivalent to *stream_ >> value_; return /*iterator*/{*this};, where stream_ is the
   stored pointer to stream and value_ is the stored value of Val. std::ranges::basic_istream_view::end
   constexpr std::default_sentinel_t end() const noexcept; (since C++20)
   Equivalent to return std::default_sentinel;.
   Nested classes
   iterator the iterator type of basic_istream_view
   (C++20) (exposition-only member class*)

Example
// Run this code
 #include <algorithm>
 #include <iomanip>
 #include <iostream>
 #include <iterator>
 #include <ranges>
 #include <sstream>
 #include <string>
 int main()
 {
     auto words = std::istringstream{"today is yesterday’s tomorrow"};
     for (const auto& s : std::views::istream<std::string>(words))
         std::cout << std::quoted(s, '/') << ' ';
     std::cout << '\n';
     auto floats = std::istringstream{"1.1 2.2\t3.3\v4.4\f55\n66\r7.7 8.8"};
     std::ranges::copy(
         std::views::istream<float>(floats),
         std::ostream_iterator<float>{std::cout, ", "}
     );
     std::cout << '\n';
 }

Output:
 /today/ /is/ /yesterday’s/ /tomorrow/
 1.1, 2.2, 3.3, 4.4, 55, 66, 7.7, 8.8,
   Defect reports
   The following behavior-changing defect reports were applied retroactively to
   previously published C++ standards.
      DR Applied to Behavior as published Correct behavior
                       default constructor was provided as removed along with the
   P2325R3 C++20 view requirement
                       must be default_initializable
   LWG 3568 C++20 P2325R3 accidentally made the stored restored to
                       value default-initialized value-initialization
                       ranges::istream_view was a function made an alias template;
   P2432R1 C++20 template and customization point objects
                       did not follow the naming convention added

See also
   istream_iterator input iterator that reads from std::basic_istream
                    (class template)