Difference between revisions of "cpp/io/basic spanbuf"

Latest revision as of 14:13, 30 October 2024

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>

[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] 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*)

[edit] Member functions

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

[edit] Non-member functions

std::swap(std::basic_spanbuf)

(C++23)

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

(destructor) [virtual]	destructs the `basic_streambuf` object (virtual public member function of `std::basic_streambuf<CharT,Traits>`) [edit]
Locales
pubimbue	invokes imbue() (public member function of `std::basic_streambuf<CharT,Traits>`) [edit]
getloc	obtains a copy of the associated locale (public member function of `std::basic_streambuf<CharT,Traits>`) [edit]
Positioning
pubsetbuf	invokes setbuf() (public member function of `std::basic_streambuf<CharT,Traits>`) [edit]
pubseekoff	invokes seekoff() (public member function of `std::basic_streambuf<CharT,Traits>`) [edit]
pubseekpos	invokes seekpos() (public member function of `std::basic_streambuf<CharT,Traits>`) [edit]
pubsync	invokes sync() (public member function of `std::basic_streambuf<CharT,Traits>`) [edit]
Get area
in_avail	obtains the number of characters immediately available in the get area (public member function of `std::basic_streambuf<CharT,Traits>`) [edit]
snextc	advances the input sequence, then reads one character without advancing again (public member function of `std::basic_streambuf<CharT,Traits>`) [edit]
sbumpcstossc (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]
sgetc	reads one character from the input sequence without advancing the sequence (public member function of `std::basic_streambuf<CharT,Traits>`) [edit]
sgetn	invokes xsgetn() (public member function of `std::basic_streambuf<CharT,Traits>`) [edit]
Put area
sputc	writes one character to the put area and advances the next pointer (public member function of `std::basic_streambuf<CharT,Traits>`) [edit]
sputn	invokes xsputn() (public member function of `std::basic_streambuf<CharT,Traits>`) [edit]
Putback
sputbackc	puts one character back in the input sequence (public member function of `std::basic_streambuf<CharT,Traits>`) [edit]
sungetc	moves the next pointer in the input sequence back by one (public member function of `std::basic_streambuf<CharT,Traits>`) [edit]

Protected member functions

(constructor)	constructs a `basic_streambuf` object (protected member function) [edit]
operator= (C++11)	replaces a `basic_streambuf` object (protected member function) [edit]
swap (C++11)	swaps two `basic_streambuf` objects (protected member function) [edit]
Locales
imbue [virtual]	changes the associated locale (virtual protected member function of `std::basic_streambuf<CharT,Traits>`) [edit]
Positioning
setbuf [virtual]	replaces the buffer with user-defined array, if permitted (virtual protected member function of `std::basic_streambuf<CharT,Traits>`) [edit]
seekoff [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]
seekpos [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]
sync [virtual]	synchronizes the buffers with the associated character sequence (virtual protected member function of `std::basic_streambuf<CharT,Traits>`) [edit]
Get area
showmanyc [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]
underflow [virtual]	reads characters from the associated input sequence to the get area (virtual protected member function of `std::basic_streambuf<CharT,Traits>`) [edit]
uflow [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]
xsgetn [virtual]	reads multiple characters from the input sequence (virtual protected member function of `std::basic_streambuf<CharT,Traits>`) [edit]
ebackgptregptr	returns a pointer to the beginning, current character and the end of the get area (protected member function) [edit]
gbump	advances the next pointer in the input sequence (protected member function) [edit]
setg	repositions the beginning, next, and end pointers of the input sequence (protected member function) [edit]
Put area
xsputn [virtual]	writes multiple characters to the output sequence (virtual protected member function of `std::basic_streambuf<CharT,Traits>`) [edit]
overflow [virtual]	writes characters to the associated output sequence from the put area (virtual protected member function of `std::basic_streambuf<CharT,Traits>`) [edit]
pbasepptrepptr	returns a pointer to the beginning, current character and the end of the put area (protected member function) [edit]
pbump	advances the next pointer of the output sequence (protected member function) [edit]
setp	repositions the beginning, next, and end pointers of the output sequence (protected member function) [edit]
Putback
pbackfail [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 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

[edit] See also

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

@@ Line 28: / Line 28: @@
 {{dsc h2|Public member functions}}
 {{dsc inc|cpp/io/basic_spanbuf/dsc constructor}}
-{{dsc mem vdtor|cpp/io/basic_spanbuf|notes={{mark c++23}}|inlinemem=true|destroys the {{tt|basic_spanbuf}} object}}
+{{dsc mem vdtor|cpp/io/basic_spanbuf|inlinemem=true|destroys the {{tt|basic_spanbuf}} object}}
 {{dsc inc|cpp/io/basic_spanbuf/dsc operator{{=}}}}
 {{dsc inc|cpp/io/basic_spanbuf/dsc swap}}

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I/O manipulators
Print functions (C++23)
C-style I/O
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basic_streambuf
basic_filebuf
basic_stringbuf
basic_spanbuf (C++23)
strstreambuf (C++98/26*)
basic_syncbuf (C++20)
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basic_osyncstream (C++20)
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streamoff
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Error category interface
iostream_category (C++11)
io_errc (C++11)

Public member functions
basic_spanbuf::basic_spanbuf (C++23)
basic_spanbuf::operator= (C++23)
basic_spanbuf::swap (C++23)
basic_spanbuf::span (C++23)
Protected member functions
basic_spanbuf::setbuf (C++23)
basic_spanbuf::seekoff (C++23)
basic_spanbuf::seekpos (C++23)
Non-member functions
swap(std::basic_spanbuf) (C++23)

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Difference between revisions of "cpp/io/basic spanbuf"

Latest revision as of 14:13, 30 October 2024

Contents

[edit] Member types

[edit] Data members

[edit] Member functions

Public member functions

Protected member functions

[edit] Non-member functions

Inherited from std::basic_streambuf

Member types

Member functions

Locales

Positioning

Get area

Put area

Putback

Protected member functions

Locales

Positioning

Get area

Put area

Putback

[edit] Notes

[edit] See also

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