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buffer Class Referencefinal

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
 
bufferoperator= (buffer const &buf)
 
bufferoperator= (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)
 
bufferoperator+= (unsigned char v)
 
bufferoperator+= (std::string_view const &str)
 
bufferoperator+= (std::vector< uint8_t > const &data)
 
bufferoperator+= (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
https.cpp, and nonblocking_process.cpp.

Member Function Documentation

◆ add()

void add ( 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:
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
The buffer class is a simple buffer where data can be appended at the end and consumed at the front....
Definition: buffer.hpp:27
unsigned char const * get() const
Undefined if buffer is empty.
Definition: buffer.hpp:45
void add(size_t added)
Increase size by the passed amount. Call this after having obtained a writable buffer with get(size_t...
@ read
Data has become available.

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