buffer Class Reference

The buffer class is a simple buffer where data can be appended at the end and consumed at the front. Think of it as a deque with contiguous storage. More...

#include <buffer.hpp>

Public Types
typedef unsigned char	value_type

Public Member Functions
	buffer (size_t capacity)
	Initially reserves the passed capacity.
	buffer (buffer const &buf)
	buffer (buffer &&buf) noexcept
buffer &	operator= (buffer const &buf)
buffer &	operator= (buffer &&buf) noexcept
unsigned char const *	get () const
	Undefined if buffer is empty.
unsigned char *	get ()
unsigned char *	data ()
	Same as get()
unsigned char const *	data () const
unsigned char *	get (size_t write_size)
	Returns a writable buffer guaranteed to be large enough for write_size bytes, call add when done. More...
void	add (size_t added)
	Increase size by the passed amount. Call this after having obtained a writable buffer with get(size_t write_size)
template<typename T , std::enable_if_t< std::is_signed_v< T >, int > = 0>
void	add (T added)
	Overload of add for signed types, only adds if value is positive. More...
void	consume (size_t consumed)
	Removes consumed bytes from the beginning of the buffer. More...
size_t	size () const
void	clear ()
void	append (unsigned char const *data, size_t len)
	Appends the passed data to the buffer. More...
void	append (std::string_view const &str)
void	append (std::vector< uint8_t > const &data)
void	append (fz::buffer const &b)
void	append (unsigned char v)
void	append (size_t len, unsigned char c)
buffer &	operator+= (unsigned char v)
buffer &	operator+= (std::string_view const &str)
buffer &	operator+= (std::vector< uint8_t > const &data)
buffer &	operator+= (fz::buffer const &b)
bool	empty () const
	operator bool () const
size_t	capacity () const
void	reserve (size_t capacity)
void	resize (size_t size)
unsigned char	operator[] (size_t i) const
	Gets element at offset i. Does not do bounds checking.
unsigned char &	operator[] (size_t i)
bool	operator== (buffer const &rhs) const
bool	operator!= (buffer const &rhs) const
std::string_view	to_view () const

Detailed Description

The buffer class is a simple buffer where data can be appended at the end and consumed at the front. Think of it as a deque with contiguous storage.

This class is useful when buffering data for sending over the network, or for buffering data for further piecemeal processing after having received it.

In general, copying/moving data around is expensive and allocations are even more expensive. Using this class helps to limit both to the bare minimum.

Examples

nonblocking_process.cpp, and raw_https.cpp.

Member Function Documentation

add()

void add ( T  added )

inline

Overload of add for signed types, only adds if value is positive.

Does nothing on values <= 0, useful for directly passing the ssize_t result of the system's recv() or read() functions.

append()

void append	(	unsigned char const *	data,
		size_t	len
	)

Appends the passed data to the buffer.

The number of reallocations as result to repeated append are amortized O(1)

Examples

nonblocking_process.cpp.

clear()

void clear

(

)

Does not release the memory.

consume()

void consume

(

size_t

consumed

)

Removes consumed bytes from the beginning of the buffer.

Undefined if consumed > size()

Examples

nonblocking_process.cpp.

get()

unsigned char* get

(

size_t

write_size

)

Returns a writable buffer guaranteed to be large enough for write_size bytes, call add when done.

The returned pointer is pointing just after the data already stored in the buffer.

Calling this function does not does not affect size().

See also

append

Example:

fz::buffer buf;
size_t to_read = 44;
int read = recv(fd, buf.get(to_read), to_read, 0); // Read stuff from some socket
if (read > 0)
    buf.add(read); // Adjust size with the amount actually written into the buffer

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The documentation for this class was generated from the following file:

• buffer.hpp