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std::basic_spanbuf

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< cpp‎ | io
 
 
Input/output library
I/O manipulators
C-style I/O
Buffers
basic_spanbuf
(C++23)
(deprecated in C++98)
Streams
Abstractions
File I/O
String I/O
Array I/O
(deprecated in C++98)
(deprecated in C++98)
(deprecated in C++98)
Synchronized Output
Types
Error category interface
(C++11)
 
std::basic_spanbuf
Public member functions
Protected member functions
Non-member functions
 
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.

Typical implementations of std::basic_spanbuf add two member subobjects: a std::ios_base::openmode recording the open mode, and a std::span<CharT> referencing the underlying buffer.

Two specializations for common character types are also defined:

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

Contents

[edit] Member types

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

[edit] Member functions

Public member functions
constructs a basic_spanbuf object
(public member function) [edit]
(destructor)
[virtual] (C++23)
destroys the basic_spanbuf object
(virtual public member function)
(C++23)
assigns a basic_spanbuf object
(public member function) [edit]
(C++23)
swaps two basic_spanbuf objects
(public member function) [edit]
(C++23)
obtains or initializes an underlying buffer according to mode
(public member function) [edit]
Protected member functions
[virtual] (C++23)
attempts to replace the controlled character sequence with an array
(virtual protected member function) [edit]
[virtual] (C++23)
repositions the next pointer in the input sequence, output sequence, or both, using relative addressing
(virtual protected member function) [edit]
[virtual] (C++23)
repositions the next pointer in the input sequence, output sequence, or both using absolute addressing
(virtual protected member function) [edit]

[edit] Non-member functions

specializes the std::swap algorithm
(function template) [edit]

Inherited from std::basic_streambuf

Member types

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

Member functions

[virtual]
destructs the basic_streambuf object
(virtual public member function of std::basic_streambuf<CharT,Traits>) [edit]
Locales
invokes imbue()
(public member function of std::basic_streambuf<CharT,Traits>) [edit]
obtains a copy of the associated locale
(public member function of std::basic_streambuf<CharT,Traits>) [edit]
Positioning
invokes setbuf()
(public member function of std::basic_streambuf<CharT,Traits>) [edit]
invokes seekoff()
(public member function of std::basic_streambuf<CharT,Traits>) [edit]
invokes seekpos()
(public member function of std::basic_streambuf<CharT,Traits>) [edit]
invokes sync()
(public member function of std::basic_streambuf<CharT,Traits>) [edit]
Get area
obtains the number of characters immediately available in the get area
(public member function of std::basic_streambuf<CharT,Traits>) [edit]
advances the input sequence, then reads one character without advancing again
(public member function of std::basic_streambuf<CharT,Traits>) [edit]
(removed in C++17)
reads one character from the input sequence and advances the sequence
(public member function of std::basic_streambuf<CharT,Traits>) [edit]
reads one character from the input sequence without advancing the sequence
(public member function of std::basic_streambuf<CharT,Traits>) [edit]
invokes xsgetn()
(public member function of std::basic_streambuf<CharT,Traits>) [edit]
Put area
writes one character to the put area and advances the next pointer
(public member function of std::basic_streambuf<CharT,Traits>) [edit]
invokes xsputn()
(public member function of std::basic_streambuf<CharT,Traits>) [edit]
Putback
puts one character back in the input sequence
(public member function of std::basic_streambuf<CharT,Traits>) [edit]
moves the next pointer in the input sequence back by one
(public member function of std::basic_streambuf<CharT,Traits>) [edit]

Protected member functions

constructs a basic_streambuf object
(protected member function) [edit]
(C++11)
replaces a basic_streambuf object
(protected member function) [edit]
(C++11)
swaps two basic_streambuf objects
(protected member function) [edit]
Locales
[virtual]
changes the associated locale
(virtual protected member function of std::basic_streambuf<CharT,Traits>) [edit]
Positioning
[virtual]
replaces the buffer with user-defined array, if permitted
(virtual protected member function of std::basic_streambuf<CharT,Traits>) [edit]
[virtual]
repositions the next pointer in the input sequence, output sequence, or both, using relative addressing
(virtual protected member function of std::basic_streambuf<CharT,Traits>) [edit]
[virtual]
repositions the next pointer in the input sequence, output sequence, or both using absolute addressing
(virtual protected member function of std::basic_streambuf<CharT,Traits>) [edit]
[virtual]
synchronizes the buffers with the associated character sequence
(virtual protected member function of std::basic_streambuf<CharT,Traits>) [edit]
Get area
[virtual]
obtains the number of characters available for input in the associated input sequence, if known
(virtual protected member function of std::basic_streambuf<CharT,Traits>) [edit]
[virtual]
reads characters from the associated input sequence to the get area
(virtual protected member function of std::basic_streambuf<CharT,Traits>) [edit]
[virtual]
reads characters from the associated input sequence to the get area and advances the next pointer
(virtual protected member function of std::basic_streambuf<CharT,Traits>) [edit]
[virtual]
reads multiple characters from the input sequence
(virtual protected member function of std::basic_streambuf<CharT,Traits>) [edit]
returns a pointer to the beginning, current character and the end of the get area
(protected member function) [edit]
advances the next pointer in the input sequence
(protected member function) [edit]
repositions the beginning, next, and end pointers of the input sequence
(protected member function) [edit]
Put area
[virtual]
writes multiple characters to the output sequence
(virtual protected member function of std::basic_streambuf<CharT,Traits>) [edit]
[virtual]
writes characters to the associated output sequence from the put area
(virtual protected member function of std::basic_streambuf<CharT,Traits>) [edit]
returns a pointer to the beginning, current character and the end of the put area
(protected member function) [edit]
advances the next pointer of the output sequence
(protected member function) [edit]
repositions the beginning, next, and end pointers of the output sequence
(protected member function) [edit]
Putback
[virtual]
puts a character back into the input sequence, possibly modifying the input sequence
(virtual protected member function of std::basic_streambuf<CharT,Traits>) [edit]

[edit] Notes

std::basic_spanbuf does not owns 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.

[edit] See also

implements raw string device
(class template) [edit]
(deprecated in C++98)
implements raw character array device
(class) [edit]