| std::basic_spanbuf(3) | C++ Standard Libary | std::basic_spanbuf(3) |
NAME¶
std::basic_spanbuf - std::basic_spanbuf
Synopsis¶
Defined in header <spanstream>
template<
class CharT,
class Traits = std::char_traits<CharT> (since C++23)
> class basic_spanbuf
: public std::basic_streambuf<CharT, Traits>
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
(C++23) (public member function)
destructor destroys the basic_spanbuf object
[virtual] (C++23) (virtual public member function)
operator= assigns a basic_spanbuf object
(C++23) (public member function)
swap swaps two basic_spanbuf objects
(C++23) (public member function)
span obtains or initializes an underlying buffer according to mode
(C++23) (public member function)
Protected member functions¶
setbuf attempts to replace the controlled character sequence with
an
[virtual] (C++23) array
(virtual protected member function)
seekoff repositions the next pointer in the input sequence, output
[virtual] (C++23) sequence, or both, using relative addressing
(virtual protected member function)
seekpos repositions the next pointer in the input sequence, output
[virtual] (C++23) sequence, or both using absolute addressing
(virtual protected member function)
Non-member functions¶
std::swap(std::basic_spanbuf) specializes the std::swap algorithm
(C++23) (function template)
Inherited from std::basic_streambuf
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
Member functions¶
destructor destructs the basic_streambuf object
[virtual] (virtual public member function
of
std::basic_streambuf<CharT,Traits>)
Locales¶
invokes imbue()
pubimbue (public member function of
std::basic_streambuf<CharT,Traits>)
obtains a copy of the associated locale
getloc (public member function of
std::basic_streambuf<CharT,Traits>)
Positioning¶
invokes setbuf()
pubsetbuf (public member function of
std::basic_streambuf<CharT,Traits>)
invokes seekoff()
pubseekoff (public member function of
std::basic_streambuf<CharT,Traits>)
invokes seekpos()
pubseekpos (public member function of
std::basic_streambuf<CharT,Traits>)
invokes sync()
pubsync (public member function of
std::basic_streambuf<CharT,Traits>)
Get area¶
obtains the number of characters immediately available in the get
in_avail area
(public member function of
std::basic_streambuf<CharT,Traits>)
advances the input sequence, then reads one character without
snextc advancing again
(public member function of
std::basic_streambuf<CharT,Traits>)
sbumpc reads one character from the input sequence and advances the
stossc sequence
(removed in C++17) (public member function of
std::basic_streambuf<CharT,Traits>)
reads one character from the input sequence without advancing the
sgetc sequence
(public member function of
std::basic_streambuf<CharT,Traits>)
invokes xsgetn()
sgetn (public member function of
std::basic_streambuf<CharT,Traits>)
Put area¶
writes one character to the put area and advances the next
sputc pointer
(public member function of
std::basic_streambuf<CharT,Traits>)
invokes xsputn()
sputn (public member function of
std::basic_streambuf<CharT,Traits>)
Putback¶
puts one character back in the input sequence
sputbackc (public member function of
std::basic_streambuf<CharT,Traits>)
moves the next pointer in the input sequence back by one
sungetc (public member function of
std::basic_streambuf<CharT,Traits>)
Protected member functions¶
constructor constructs a basic_streambuf object
(protected member function)
operator= replaces a basic_streambuf object
(C++11) (protected member function)
swap swaps two basic_streambuf objects
(C++11) (protected member function)
Locales¶
imbue changes the associated locale
[virtual] (virtual protected member function
of
std::basic_streambuf<CharT,Traits>)
Positioning¶
setbuf replaces the buffer with user-defined array, if permitted
[virtual] (virtual protected member function
of
std::basic_streambuf<CharT,Traits>)
repositions the next pointer in the input sequence, output sequence,
seekoff or both, using relative addressing
[virtual] (virtual protected member
function of
std::basic_streambuf<CharT,Traits>)
repositions the next pointer in the input sequence, output sequence,
seekpos or both using absolute addressing
[virtual] (virtual protected member
function of
std::basic_streambuf<CharT,Traits>)
sync synchronizes the buffers with the associated character sequence
[virtual] (virtual protected member
function of
std::basic_streambuf<CharT,Traits>)
Get area¶
obtains the number of characters available for input in the
associated
showmanyc input sequence, if known
[virtual] (virtual protected member function
of
std::basic_streambuf<CharT,Traits>)
underflow reads characters from the associated input sequence to the get
area
[virtual] (virtual protected member
function of
std::basic_streambuf<CharT,Traits>)
reads characters from the associated input sequence to the get area
uflow and advances the next pointer
[virtual] (virtual protected member
function of
std::basic_streambuf<CharT,Traits>)
xsgetn reads multiple characters from the input sequence
[virtual] (virtual protected member
function of
std::basic_streambuf<CharT,Traits>)
eback returns a pointer to the beginning, current character and the end
of
gptr the get area
egptr (protected member function)
gbump advances the next pointer in the input sequence
(protected member function)
repositions the beginning, next, and end pointers of the input
setg sequence
(protected member function)
Put area¶
xsputn writes multiple characters to the output sequence
[virtual] (virtual protected member function
of
std::basic_streambuf<CharT,Traits>)
overflow writes characters to the associated output sequence from the put
area
[virtual] (virtual protected member
function of
std::basic_streambuf<CharT,Traits>)
pbase returns a pointer to the beginning, current character and the end
of
pptr the put area
epptr (protected member function)
pbump advances the next pointer of the output sequence
(protected member function)
repositions the beginning, next, and end pointers of the output
setp sequence
(protected member function)
Putback¶
puts a character back into the input sequence, possibly modifying
the
pbackfail input sequence
[virtual] (virtual protected member function
of
std::basic_streambuf<CharT,Traits>)
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 objects.
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 implements raw character array device
(deprecated in C++98) (class)
(removed in C++26)
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