Difference between revisions of "cpp/io/basic spanbuf"
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(Applied {{cpp/basic char typedefs}} and {{cpp/io/member types}}.) |
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{{cpp/io/basic_spanbuf/navbar}} | {{cpp/io/basic_spanbuf/navbar}} | ||
{{ddcl|header=spanstream|since=c++23|1= | {{ddcl|header=spanstream|since=c++23|1= | ||
| − | template< | + | template< |
| − | class CharT, | + | class CharT, |
class Traits = std::char_traits<CharT> | class Traits = std::char_traits<CharT> | ||
| − | > class basic_spanbuf : public std::basic_streambuf<CharT, Traits> | + | > class basic_spanbuf |
| + | : public std::basic_streambuf<CharT, Traits> | ||
}} | }} | ||
| Line 11: | Line 12: | ||
{{tt|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. | {{tt|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. | ||
| − | |||
| − | |||
{{cpp/basic char typedefs|spanbuf|spanstream}} | {{cpp/basic char typedefs|spanbuf|spanstream}} | ||
{{cpp/io/member types}} | {{cpp/io/member types}} | ||
| + | |||
| + | ===Data members=== | ||
| + | {{dsc begin}} | ||
| + | {{dsc hitem|Member name|Definition}} | ||
| + | {{dsc|{{tti|mod}} {{mark|private}}|A {{lc|std::ios_base::openmode}} recording the open mode.<br>{{mark expos mem obj}}}} | ||
| + | {{dsc|{{tti|buf}} {{mark|private}}|A {{c/core|std::span<CharT>}} referencing the underlying buffer.<br>{{mark expos mem obj}}}} | ||
| + | {{dsc end}} | ||
===Member functions=== | ===Member functions=== | ||
{{dsc begin}} | {{dsc begin}} | ||
| − | {{dsc h2 | Public member functions}} | + | {{dsc h2|Public member functions}} |
| − | {{dsc inc | cpp/io/basic_spanbuf/dsc constructor}} | + | {{dsc inc|cpp/io/basic_spanbuf/dsc constructor}} |
| − | {{dsc mem vdtor | cpp/io/basic_spanbuf | + | {{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 operator{{=}}}} |
| − | {{dsc inc | cpp/io/basic_spanbuf/dsc swap}} | + | {{dsc inc|cpp/io/basic_spanbuf/dsc swap}} |
| − | {{dsc inc | cpp/io/basic_spanbuf/dsc span}} | + | {{dsc inc|cpp/io/basic_spanbuf/dsc span}} |
| − | {{dsc h2 | Protected member functions}} | + | {{dsc h2|Protected member functions}} |
| − | {{dsc inc | cpp/io/basic_spanbuf/dsc setbuf}} | + | {{dsc inc|cpp/io/basic_spanbuf/dsc setbuf}} |
| − | {{dsc inc | cpp/io/basic_spanbuf/dsc seekoff}} | + | {{dsc inc|cpp/io/basic_spanbuf/dsc seekoff}} |
| − | {{dsc inc | cpp/io/basic_spanbuf/dsc seekpos}} | + | {{dsc inc|cpp/io/basic_spanbuf/dsc seekpos}} |
{{dsc end}} | {{dsc end}} | ||
===Non-member functions=== | ===Non-member functions=== | ||
{{dsc begin}} | {{dsc begin}} | ||
| − | {{dsc inc | cpp/io/basic_spanbuf/dsc swap2}} | + | {{dsc inc|cpp/io/basic_spanbuf/dsc swap2}} |
{{dsc end}} | {{dsc end}} | ||
| Line 49: | Line 55: | ||
===See also=== | ===See also=== | ||
{{dsc begin}} | {{dsc begin}} | ||
| − | {{dsc inc | cpp/io/dsc basic_stringbuf}} | + | {{dsc inc|cpp/io/dsc basic_stringbuf}} |
| − | {{dsc inc | cpp/io/dsc strstreambuf}} | + | {{dsc inc|cpp/io/dsc strstreambuf}} |
{{dsc end}} | {{dsc end}} | ||
{{langlinks|de|es|fr|it|ja|pt|ru|zh}} | {{langlinks|de|es|fr|it|ja|pt|ru|zh}} | ||
Latest revision as of 14:13, 30 October 2024
| 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> |
Contents |
[edit] 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
|
[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 | |
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) |
[edit] 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 | |
| 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] |
changes 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>)
|
[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
| implements raw string device (class template) | |
| (deprecated in C++98)(removed in C++26) |
implements raw character array device (class) |
