Represents a file of unsigned integers compressed using gamma compression. More...

Classes
class	compressed_file_reader_exception
	Basic exception for compressed_file_reader interactions. More...

Public Member Functions
	compressed_file_reader (const mmap_file &file, std::function< uint64_t(uint64_t)> mapping)
	Constructor; opens a compressed file for reading using the given mapping. More...

	compressed_file_reader (const std::string &filename, std::function< uint64_t(uint64_t)> mapping)
	Constructor to create a new mmap file for reading. More...

	~compressed_file_reader ()
	Destructor.

void	reset ()
	Sets the cursor back to the beginning of the file.

void	close ()
	Closes this compressed file.

void	seek (uint64_t bit_offset)
	Sets the cursor to the specified position in the file. More...

bool	has_next () const

uint64_t	next ()

std::string	next_string ()

uint64_t	bit_location () const

	operator bool () const

Private Member Functions
void	get_next ()
	Seeks to the next compressed number and returns the current cached value.

bool	read_bit ()

Private Attributes
std::unique_ptr< mmap_file >	file_
	Pointer to the mmap_file we are reading: nullptr if we don't own it, initialized if we do.

char *	start_
	Pointer to the beginning of the compressed file (which will be in memory most of the time)

uint64_t	size_
	the number of bytes in this compressed file

int	status_
	reading/writing status

uint64_t	current_value_
	current numeric value that was read

uint64_t	current_char_
	current byte in the compressed file

uint8_t	current_bit_
	current bit inside the current byte

std::function< uint64_t(uint64_t)>	mapping_
	hold the (actual -> compressed id) mapping

Detailed Description

Represents a file of unsigned integers compressed using gamma compression.

Constructor & Destructor Documentation

meta::io::compressed_file_reader::compressed_file_reader	(	const mmap_file &	file,
		std::function< uint64_t(uint64_t)>	mapping
	)

Constructor; opens a compressed file for reading using the given mapping.

Parameters

file	The file to read from
mapping	A function to map the original numbers to their compressed id, usually to take advantage of a skewed distribution of towards many small numbers

meta::io::compressed_file_reader::compressed_file_reader	(	const std::string &	filename,
		std::function< uint64_t(uint64_t)>	mapping
	)

Constructor to create a new mmap file for reading.

Parameters

filename	The filename for the new file to read from
mapping	A function to map the original numbers to their compressed id, usually to take advantage of a skewed distribution of towards many small numbers

void meta::io::compressed_file_reader::seek ( uint64_t bit_offset )

Sets the cursor to the specified position in the file.

It is up to the user to specify a valid position.

Parameters

bit_offset Bit offset into the file

bool meta::io::compressed_file_reader::has_next ( ) const

uint64_t meta::io::compressed_file_reader::next ( )

std::string meta::io::compressed_file_reader::next_string ( )

uint64_t meta::io::compressed_file_reader::bit_location ( ) const

meta::io::compressed_file_reader::operator bool ( ) const

inline

bool meta::io::compressed_file_reader::read_bit ( )

private

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