Standard library header <syncstream>

C++

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Named requirements

Language support library

Concepts library (C++20)

Diagnostics library

Utilities library

Strings library

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Algorithms library

Iterators library

Numerics library

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Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

Filesystem library (C++17)

Technical Specifications

Standard Library header files

Language Support
<cstddef> <limits> <climits> <contract>	<cfloat> <cstdint> <new> <version>	<typeinfo> <exception> <initializer_list>	<csignal> <csetjmp> <cstdarg>
Concepts
<concepts>
Diagnostics
<stdexcept>	<cassert>	<cerrno>	<system_error>
General utilities
<utility> <memory> <memory_resource> <scoped_allocator> <compare>	<bitset> <tuple> <optional> <any> <variant>	<type_traits> <ratio> <chrono> <typeindex> <functional>	<ctime> <cstdlib>
Strings
<string> <string_view>	<cctype> <cwctype>	<cwchar> <cuchar>	<cstring> <charconv>
Localization
<locale>	<codecvt>	<clocale>
Containers
<span> <array> <vector>	<deque> <forward_list> <list>	<map> <set> <queue>	<unordered_map> <unordered_set> <stack>
Iterators
<iterator>
Algorithms
<algorithm>	<execution>
Numerics
<complex> <random>	<valarray> <numeric>	<cfenv> <cmath>	<bit>
Input/Output
<iosfwd> <ios> <iomanip> <streambuf>	<istream> <ostream> <iostream>	<sstream> <fstream> <syncstream>	<cstdio> <cinttypes> <strstream>
Regular expressions
<regex>
Filesystem support
<filesystem>
Thread support
<thread> <atomic>	<mutex> <shared_mutex>	<condition_variable> <future>
C compatibility
<ciso646> <cstdalign>	<cstdbool> <ccomplex>	<ctgmath>

This header is part of the Input/Output library.

Includes
<ostream>
Classes
basic_syncbuf (C++20)	synchronized output device wrapper (class template)
basic_osyncstream (C++20)	synchronized output stream wrapper (class template)
Typedefs
syncbuf	basic_syncbuf<char>
wsyncbuf	basic_syncbuf<wchar_t>
osyncstream	basic_osyncstream<char>
wosyncstream	basic_osyncstream<wchar_t>
Functions
std::swap(std::basic_syncbuf) (C++20)	specializes the std::swap algorithm (function template)

Synopsis

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>;

template <class CharT, class Traits, class Allocator>
  void swap( std::basic_syncbuf<CharT, Traits, Allocator>& lhs,
             std::basic_syncbuf<CharT, Traits, Allocator>& rhs );

}

Class std::basic_syncbuf

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>;

  // Constructors/destructor:
  explicit
  basic_syncbuf(streambuf_type* obuf = nullptr)
    : basic_syncbuf(obuf, Allocator()) {}
  basic_syncbuf(streambuf_type* ,
                const Allocator&);
  basic_syncbuf(basic_syncbuf&&);
  ~basic_syncbuf();

  // Assign/swap:
  basic_syncbuf& operator=(basic_syncbuf&&);
  void swap(basic_syncbuf &);

  // Members:
  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
};

Class std::basic_osyncstream

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>;

  // Constructors/destructor:
  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();

  // Assign:
  basic_osyncstream& operator=(basic_osyncstream&&) noexcept;

  // Members:
  void emit();
  streambuf_type* get_wrapped() const noexcept;
  syncbuf_type* rdbuf() const noexcept { return &sb ; }

private:
  syncbuf_type sb; // exposition only
};