标准库标头 <syncstream> (C++20)

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此头文件是输入/输出库的一部分。

包含

 std::basic_ostream 、 std::basic_iostream 类模板与 typedef[编辑]

类

(C++20)
 同步输出设备的包装器
(类模板) [编辑]
(C++20)
 同步输出流的包装器
(类模板) [编辑]
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)

函数

(C++20)
 特化 std::swap 算法
(函数模板) [编辑]

概要

#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>;
}

类模板 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>;

    // 构造与析构
    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();

    // 赋值与交换
    basic_syncbuf& operator=(basic_syncbuf&&);
    void swap(basic_syncbuf&);

    // 成员函数
    bool emit();
    streambuf_type* get_wrapped() const noexcept;
    allocator_type get_allocator() const noexcept;
    void set_emit_on_sync(bool) noexcept;

  protected:
    // 覆盖的虚函数
    int sync() override;

  private:
    streambuf_type* wrapped;    // 仅用于阐释
    bool emit_on_sync{};        // 仅用于阐释
  };

  // 特化的算法
  template<class CharT, class Traits, class Allocator>
    void swap(basic_syncbuf<CharT, Traits, Allocator>&,
              basic_syncbuf<CharT, Traits, Allocator>&);
}

类模板 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>;

    // 构造与析构
    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();

    // 赋值与交换
    basic_osyncstream& operator=(basic_osyncstream&&) noexcept;

    // 成员函数
    void emit();
    streambuf_type* get_wrapped() const noexcept;
    syncbuf_type* rdbuf() const noexcept
    { return const_cast<syncbuf_type*>(addressof(sb)); }

  private:
    syncbuf_type sb;    // 仅用于阐释
  };
}