cppdraft_translate/cppdraft/stringbuf/general.md

[stringbuf.general]

31 Input/output library [input.output]

31.8 String-based streams [string.streams]

31.8.2 Class template basic_stringbuf [stringbuf]

31.8.2.1 General [stringbuf.general]

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namespace std {template<class charT, class traits = char_traits, class Allocator = allocator>class basic_stringbuf : 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; // [stringbuf.cons], constructors basic_stringbuf() : basic_stringbuf(ios_base::in | ios_base::out) {}explicit basic_stringbuf(ios_base::openmode which); explicit basic_stringbuf(const basic_string<charT, traits, Allocator>& s, ios_base::openmode which = ios_base::in | ios_base::out); explicit basic_stringbuf(const Allocator& a): basic_stringbuf(ios_base::in | ios_base::out, a) {} basic_stringbuf(ios_base::openmode which, const Allocator& a); explicit basic_stringbuf( basic_string<charT, traits, Allocator>&& s, ios_base::openmode which = ios_base::in | ios_base::out); template basic_stringbuf(const basic_string<charT, traits, SAlloc>& s, const Allocator& a): basic_stringbuf(s, ios_base::in | ios_base::out, a) {}template basic_stringbuf(const basic_string<charT, traits, SAlloc>& s, ios_base::openmode which, const Allocator& a); templateexplicit basic_stringbuf(const basic_string<charT, traits, SAlloc>& s, ios_base::openmode which = ios_base::in | ios_base::out); templateexplicit basic_stringbuf(const T& t, ios_base::openmode which = ios_base::in | ios_base::out); template basic_stringbuf(const T& t, const Allocator& a); template basic_stringbuf(const T& t, ios_base::openmode which, const Allocator& a); basic_stringbuf(const basic_stringbuf&) = delete; basic_stringbuf(basic_stringbuf&& rhs); basic_stringbuf(basic_stringbuf&& rhs, const Allocator& a); // [stringbuf.assign], assignment and swap basic_stringbuf& operator=(const basic_stringbuf&) = delete; basic_stringbuf& operator=(basic_stringbuf&& rhs); void swap(basic_stringbuf& rhs) noexcept(see below); // [stringbuf.members], getters and setters allocator_type get_allocator() const noexcept;

basic_string<charT, traits, Allocator> str() const &; template basic_string<charT,traits,SAlloc> str(const SAlloc& sa) const; basic_string<charT, traits, Allocator> str() &&; basic_string_view<charT, traits> view() const noexcept; void str(const basic_string<charT, traits, Allocator>& s); templatevoid str(const basic_string<charT, traits, SAlloc>& s); void str(basic_string<charT, traits, Allocator>&& s); templatevoid str(const T& t); protected:// [stringbuf.virtuals], overridden virtual functions int_type underflow() override; int_type pbackfail(int_type c = traits::eof()) override; int_type overflow (int_type c = traits::eof()) override; basic_streambuf<charT, traits>* setbuf(charT*, streamsize) override;

pos_type seekoff(off_type off, ios_base::seekdir way, ios_base::openmode which = ios_base::in | ios_base::out) override; pos_type seekpos(pos_type sp, ios_base::openmode which = ios_base::in | ios_base::out) override; private: ios_base::openmode mode; // exposition only basic_string<charT, traits, Allocator> buf; // exposition onlyvoid init-buf-ptrs(); // exposition only};}

1

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The classbasic_stringbuf is derived frombasic_streambuf to associate possibly the input sequence and possibly the output sequence with a sequence of arbitrarycharacters.

The sequence can be initialized from, or made available as, an object of classbasic_string.

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For the sake of exposition, the maintained data and internal pointer initialization is presented here as:

• (2.1)

  ios_base​::​openmode mode, has in set if the input sequence can be read, and out set if the output sequence can be written.

• (2.2)

  basic_string<charT, traits, Allocator> buf contains the underlying character sequence.

• (2.3)

  init-buf-ptrs() sets the base class' get area ([streambuf.get.area]) and put area ([streambuf.put.area]) pointers after initializing, moving from, or assigning to buf accordingly.