31 Input/output library [input.output]

31.9 Span-based streams [span.streams]

31.9.4 Class template basic_ispanstream [ispanstream]

31.9.4.1 General [ispanstream.general]

namespace std { template<class charT, class traits = char_traits<charT>> class basic_ispanstream : public basic_istream<charT, traits> { public: using char_type = charT; using int_type = typename traits::int_type; using pos_type = typename traits::pos_type; using off_type = typename traits::off_type; using traits_type = traits; // [ispanstream.cons], constructors explicit basic_ispanstream(std::span<charT> s, ios_base::openmode which = ios_base::in); basic_ispanstream(const basic_ispanstream&) = delete; basic_ispanstream(basic_ispanstream&& rhs); template<class ROS> explicit basic_ispanstream(ROS&& s); basic_ispanstream& operator=(const basic_ispanstream&) = delete; basic_ispanstream& operator=(basic_ispanstream&& rhs); // [ispanstream.swap], swap void swap(basic_ispanstream& rhs); // [ispanstream.members], member functions basic_spanbuf<charT, traits>* rdbuf() const noexcept; std::span<const charT> span() const noexcept; void span(std::span<charT> s) noexcept; template<class ROS> void span(ROS&& s) noexcept; private: basic_spanbuf<charT, traits> sb; // exposition only }; }

[Note 1:

Constructing an ispanstream from a string-literal includes the termination character '\0' in the underlying spanbuf.

— end note]

31.9.4.2 Constructors [ispanstream.cons]

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explicit basic_ispanstream(std::span<charT> s, ios_base::openmode which = ios_base::in);

Effects: Initializes the base class with basic_istream<charT, traits>(addressof(sb)) and sb with basic_spanbuf<charT, traits>(s, which | ios_base::in) ([spanbuf.cons]).

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basic_ispanstream(basic_ispanstream&& rhs);

Effects: Initializes the base class with std::move(rhs) and sb with std::move(rhs.sb).

Next, basic_istream<charT, traits>::set_rdbuf(addressof(sb)) is called to install the contained basic_spanbuf.

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template<class ROS> explicit basic_ispanstream(ROS&& s)

Constraints: ROS models ranges::borrowed_range.

!convertible_to<ROS, std::span<charT>> && convertible_to<ROS, std::span<charT const>> is true.

Effects: Let sp be std::span<const charT>(std::forward<ROS>(s)).

Equivalent to: basic_ispanstream(std::span<charT>(const_cast<charT*>(sp.data()), sp.size()))

31.9.4.3 Swap [ispanstream.swap]

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void swap(basic_ispanstream& rhs);

Effects: Equivalent to: basic_istream<charT, traits>::swap(rhs); sb.swap(rhs.sb);

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template<class charT, class traits>
  void swap(basic_ispanstream<charT, traits>& x, basic_ispanstream<charT, traits>& y);

Effects: Equivalent to x.swap(y).

31.9.4.4 Member functions [ispanstream.members]

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basic_spanbuf<charT, traits>* rdbuf() const noexcept;

Effects: Equivalent to: return const_cast<basic_spanbuf<charT, traits>*>(addressof(sb));

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std::span<const charT> span() const noexcept;

Effects: Equivalent to: return rdbuf()->span();

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void span(std::span<charT> s) noexcept;

Effects: Equivalent to rdbuf()->span(s).

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template<class ROS> void span(ROS&& s) noexcept;

Constraints: ROS models ranges::borrowed_range.

(!convertible_to<ROS, std::span<charT>>) && convertible_to<ROS, std::span<const charT>> is true.

Effects: Let sp be std::span<const charT>(std::forward<ROS>(s)).

Equivalent to: this->span(std::span<charT>(const_cast<charT*>(sp.data()), sp.size()));