std::basic_spanbuf

Defined in header <spanstream>
template < class CharT, class Traits = std::char_traits <CharT> > class basic_spanbuf : public std::basic_streambuf <CharT, Traits>		(since C++23)

std::basic_spanbuf is a std::basic_streambuf whose associated character sequence is a memory-resident sequence of arbitrary characters, which can be initialized from or made available as an instance of std::span<CharT>

std::basic_spanbuf performs I/O on a fixed buffer, and therefore it does not attempt to obtain a new buffer when the underlying buffer is exhausted.

Several typedefs for common character types are provided:

Defined in header <spanstream>
Type	Definition
std::spanbuf	std::basic_spanbuf<char>
std::wspanbuf	std::basic_spanbuf<wchar_t>

Member types

Member type	Definition
char_type	CharT
traits_type	Traits; the program is ill-formed if Traits::char_type is not CharT.
int_type	Traits::int_type
pos_type	Traits::pos_type
off_type	Traits::off_type

Data members

Member name	Definition
mod (private)	A std::ios_base::openmode recording the open mode. (exposition-only member object*
buf (private)	A std::span<CharT> referencing the underlying buffer. (exposition-only member object*

Member functions

Public member functions
(constructor)	constructs a basic_spanbuf object (public member function)
(destructor) [virtual]	destroys the basic_spanbuf object (virtual public member function)
operator=	assigns a basic_spanbuf object (public member function)
swap	swaps two basic_spanbuf objects (public member function)
span	obtains or initializes an underlying buffer according to mode (public member function)
Protected member functions
setbuf [virtual]	attempts to replace the controlled character sequence with an array (virtual protected member function)
seekoff [virtual]	repositions the next pointer in the input sequence, output sequence, or both, using relative addressing (virtual protected member function)
seekpos [virtual]	repositions the next pointer in the input sequence, output sequence, or both using absolute addressing (virtual protected member function)

Non-member functions

std::swap(std::basic_spanbuf) (C++23)

specializes the std::swap algorithm (function template)

Notes

std::basic_spanbuf does not own the underlying buffer.

It is the responsibility of programmers to ensure the underlying buffer is in its lifetime when used by a std::basic_spanbuf object. Additional synchronization may be needed if more than one thread operates the same underlying buffer through different std::basic_spanbuf

Feature-test macro	Value	Std	Feature
__cpp_lib_spanstream	202106L	(C++23)	std::spanbuf, std::spanstream

See also

basic_stringbuf	implements raw string device (class template)
strstreambuf (deprecated in C++98)(removed in C++26)	implements raw character array device (class)