std::basic_spanbuf
| Defined in header <spanstream>
|
||
| template< class CharT, |
(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 | |
constructs a basic_spanbuf object (public member function) | |
| (destructor) [virtual] |
destroys the basic_spanbuf object (virtual public member function) |
assigns a basic_spanbuf object (public member function) | |
swaps two basic_spanbuf objects (public member function) | |
| obtains or initializes an underlying buffer according to mode (public member function) | |
Protected member functions | |
| [virtual] |
attempts to replace the controlled character sequence with an array (virtual protected member function) |
| [virtual] |
repositions the next pointer in the input sequence, output sequence, or both, using relative addressing (virtual protected member function) |
| [virtual] |
repositions the next pointer in the input sequence, output sequence, or both using absolute addressing (virtual protected member function) |
Non-member functions
| specializes the std::swap algorithm (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
| [virtual] |
destructs the basic_streambuf object (virtual public member function of std::basic_streambuf<CharT,Traits>) |
Locales | |
| changes the associated locale and invokes imbue() (public member function of std::basic_streambuf<CharT,Traits>) | |
| obtains a copy of the associated locale (public member function of std::basic_streambuf<CharT,Traits>) | |
Positioning | |
| invokes setbuf() (public member function of std::basic_streambuf<CharT,Traits>) | |
| invokes seekoff() (public member function of std::basic_streambuf<CharT,Traits>) | |
| invokes seekpos() (public member function of std::basic_streambuf<CharT,Traits>) | |
| invokes sync() (public member function of std::basic_streambuf<CharT,Traits>) | |
Get area | |
| obtains the number of characters immediately available in the get area (public member function of std::basic_streambuf<CharT,Traits>) | |
| advances the input sequence, then reads one character without advancing again (public member function of std::basic_streambuf<CharT,Traits>) | |
| (removed in C++17) |
reads one character from the input sequence and advances the sequence (public member function of std::basic_streambuf<CharT,Traits>) |
| reads one character from the input sequence without advancing the sequence (public member function of std::basic_streambuf<CharT,Traits>) | |
| invokes xsgetn() (public member function of std::basic_streambuf<CharT,Traits>) | |
Put area | |
| writes one character to the put area and advances the next pointer (public member function of std::basic_streambuf<CharT,Traits>) | |
| invokes xsputn() (public member function of std::basic_streambuf<CharT,Traits>) | |
Putback | |
| puts one character back in the input sequence (public member function of std::basic_streambuf<CharT,Traits>) | |
| moves the next pointer in the input sequence back by one (public member function of std::basic_streambuf<CharT,Traits>) | |
Protected member functions
constructs a basic_streambuf object (protected member function) | |
| (C++11) |
replaces a basic_streambuf object (protected member function) |
| (C++11) |
swaps two basic_streambuf objects (protected member function) |
Locales | |
| [virtual] |
reacts to a change of the associated locale (virtual protected member function of std::basic_streambuf<CharT,Traits>) |
Positioning | |
| [virtual] |
replaces the buffer with user-defined array, if permitted (virtual protected member function of std::basic_streambuf<CharT,Traits>) |
| [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>) |
| [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>) |
| [virtual] |
synchronizes the buffers with the associated character sequence (virtual protected member function of std::basic_streambuf<CharT,Traits>) |
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>) |
| [virtual] |
reads characters from the associated input sequence to the get area (virtual protected member function of std::basic_streambuf<CharT,Traits>) |
| [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>) |
| [virtual] |
reads multiple characters from the input sequence (virtual protected member function of std::basic_streambuf<CharT,Traits>) |
| returns a pointer to the beginning, current character and the end of the get area (protected member function) | |
| advances the next pointer in the input sequence (protected member function) | |
| repositions the beginning, next, and end pointers of the input sequence (protected member function) | |
Put area | |
| [virtual] |
writes multiple characters to the output sequence (virtual protected member function of std::basic_streambuf<CharT,Traits>) |
| [virtual] |
writes characters to the associated output sequence from the put area (virtual protected member function of std::basic_streambuf<CharT,Traits>) |
| returns a pointer to the beginning, current character and the end of the put area (protected member function) | |
| advances the next pointer of the output sequence (protected member function) | |
| repositions the beginning, next, and end pointers of the output sequence (protected member function) | |
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>) |
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
| implements raw string device (class template) | |
| (deprecated in C++98)(removed in C++26) |
implements raw character array device (class) |