Standard library header <syncstream> (C++20)

 

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<iosfwd> <iostream> <ios> <streambuf>	<istream> <ostream> <iomanip> <print> (C++23)	<sstream> <spanstream> (C++23) <fstream> <syncstream> (C++20)	<filesystem> (C++17) <cstdio> <cinttypes> (C++11) <strstream> (C++98*)
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<stop_token> (C++20) <thread> (C++11) <atomic> (C++11)	<stdatomic.h> (C++23) <mutex> (C++11) <shared_mutex> (C++14)	<condition_variable> (C++11)   <semaphore> (C++20) <latch> (C++20)	<barrier> (C++20) <future> (C++11)
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This header is part of the Input/Output library.

Includes
<ostream>	std::basic_ostream, std::basic_iostream class templates and several typedefs
Classes
basic_syncbuf (C++20)	synchronized output device wrapper (class template)
basic_osyncstream (C++20)	synchronized output stream wrapper (class template)
syncbuf (C++20)	std::basic_syncbuf<char> (typedef)
wsyncbuf (C++20)	std::basic_syncbuf<wchar_t> (typedef)
osyncstream (C++20)	std::basic_osyncstream<char> (typedef)
wosyncstream (C++20)	std::basic_osyncstream<wchar_t> (typedef)
Functions
std::swap(std::basic_syncbuf) (C++20)	specializes the std::swap algorithm (function template)

Synopsis

#include <ostream>
 
namespace std {
  template<class CharT, class Traits = char_traits<CharT>,
           class Allocator = allocator<CharT>>
    class basic_syncbuf;
 
  using syncbuf = basic_syncbuf<char>;
  using wsyncbuf = basic_syncbuf<wchar_t>;
 
  template<class CharT, class Traits = char_traits<CharT>,
           class Allocator = allocator<CharT>>
    class basic_osyncstream;
 
  using osyncstream = basic_osyncstream<char>;
  using wosyncstream = basic_osyncstream<wchar_t>;
}

Class template std::basic_syncbuf

namespace std {
  template<class CharT, class Traits = char_traits<CharT>,
           class Allocator = allocator<CharT>>
  class basic_syncbuf : public basic_streambuf<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;
    using allocator_type = Allocator;
 
    using streambuf_type = basic_streambuf<CharT, Traits>;
 
    // construction and destruction
    basic_syncbuf()
      : basic_syncbuf(nullptr) {}
    explicit basic_syncbuf(streambuf_type* obuf)
      : basic_syncbuf(obuf, Allocator()) {}
    basic_syncbuf(streambuf_type*, const Allocator&);
    basic_syncbuf(basic_syncbuf&&);
    ~basic_syncbuf();
 
    // assignment and swap
    basic_syncbuf& operator=(basic_syncbuf&&);
    void swap(basic_syncbuf&);
 
    // member functions
    bool emit();
    streambuf_type* get_wrapped() const noexcept;
    allocator_type get_allocator() const noexcept;
    void set_emit_on_sync(bool) noexcept;
 
  protected:
    // overridden virtual functions
    int sync() override;
 
  private:
    streambuf_type* wrapped;    // exposition only
    bool emit_on_sync{};        // exposition only
  };
 
  // specialized algorithms
  template<class CharT, class Traits, class Allocator>
    void swap(basic_syncbuf<CharT, Traits, Allocator>&,
              basic_syncbuf<CharT, Traits, Allocator>&);
}

Class template std::basic_osyncstream

namespace std {
  template<class CharT, class Traits = char_traits<CharT>,
           class Allocator = allocator<CharT>>
  class basic_osyncstream : public basic_ostream<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;
 
    using allocator_type = Allocator;
    using streambuf_type = basic_streambuf<CharT, Traits>;
    using syncbuf_type   = basic_syncbuf<CharT, Traits, Allocator>;
 
    // construction and destruction
    basic_osyncstream(streambuf_type*, const Allocator&);
    explicit basic_osyncstream(streambuf_type* obuf)
      : basic_osyncstream(obuf, Allocator()) {}
    basic_osyncstream(basic_ostream<CharT, Traits>& os, const Allocator& allocator)
      : basic_osyncstream(os.rdbuf(), allocator) {}
    explicit basic_osyncstream(basic_ostream<CharT, Traits>& os)
      : basic_osyncstream(os, Allocator()) {}
    basic_osyncstream(basic_osyncstream&&) noexcept;
    ~basic_osyncstream();
 
    // assignment
    basic_osyncstream& operator=(basic_osyncstream&&) noexcept;
 
    // member functions
    void emit();
    streambuf_type* get_wrapped() const noexcept;
    syncbuf_type* rdbuf() const noexcept
    { return const_cast<syncbuf_type*>(addressof(sb)); }
 
  private:
    syncbuf_type sb;    // exposition only
  };
}