Functions
void	hash_combine (std::size_t &seed)

template<typename T , typename... Rest>
void	hash_combine (std::size_t &seed, const T &v, Rest... rest)

std::string	b64_encode (const std::vector< std::byte > &data)

std::string	b64_encode (const std::string data)

std::vector< std::byte >	b64_decode (const std::string data)

std::string	b64_tostring (const std::string data)

std::string	generate_uuid ()

bool	has_system_uuid ()

std::string	system_uuid ()

std::string	create_uuid (const std::string seed)

Detailed Description

Functions for custom hash functions

This namespace provides several tools creating user-defined hash functions and universally unique identifiers (UUIDs). The latter is important for the networking libraries, as it provides a way of uniquely referencing machines across the network.

Function Documentation

◆ b64_decode()

std::vector< std::byte > cugl::hashtool::b64_decode ( const std::string data )

Returns a byte vector decoded from the given Base 64 data

It is assumed that the data provided is a Base 64 encoding of binary data. This is a representation of binary data as all printable characters. See

https://en.wikipedia.org/wiki/Base64

Obviously b64_encode produces such data, but the data could have been produced through other means, such as via Python.

Parameters

data	The data to convert

Returns: a byte vector decoded from the given Base 64 data

◆ b64_encode() [1/2]

std::string cugl::hashtool::b64_encode ( const std::string data )

Returns a text representation of the given string in Base 64

Strings in C++ are arbitrary lists of characters, and do not have to be be printable. This means that they are not always safe for use with HTTP or similar protocols. This function encodes the string to make it safe for transmission. See

https://en.wikipedia.org/wiki/Base64

Parameters

data	The data to convert

Returns: a text representation of the given binary data in Base 64

◆ b64_encode() [2/2]

std::string cugl::hashtool::b64_encode ( const std::vector< std::byte > & data )

Returns a text representation of the given binary data in Base 64

This function represents the given binary data as printable characters, making it safe for network transfer over HTTP or similar protocols. See

https://en.wikipedia.org/wiki/Base64

Parameters

data	The data to convert

Returns: a text representation of the given binary data in Base 64

◆ b64_tostring()

std::string cugl::hashtool::b64_tostring ( const std::string data )

Returns a string decoded from the given Base 64 data

This function is an alternative to b64_decode that produces a string instead of a byte vector. It is for cases in which the user is working with strings that contain unprintable characters (e.g. UTF-8 strings).

Parameters

data	The data to convert

Returns: a string decoded from the given Base 64 data

◆ create_uuid()

std::string cugl::hashtool::create_uuid ( const std::string seed )

Returns a UUID for the given seed.

This creates a Version 5 UUID hashed the provided string. Identical seeds will produce identical UUIDs. As a Version 5 uuid, this is a 32 character hexadecimal string with dashes separating the characters into groups of 8-4-4-4-12 (as well as supporting Version 5 markers).

Returns: a UUID for the given seed.

◆ generate_uuid()

std::string cugl::hashtool::generate_uuid ( )

Returns a new randomly generated UUID

This creates a Version 4 UUID generated by a fresh std::random_device. It will be a 32 character hexadecimal string with dashes separating the characters into groups of 8-4-4-4-12 (as well as supporting Version 4 markers).

Returns: a new randomly generated UUID

◆ has_system_uuid()

bool cugl::hashtool::has_system_uuid ( )

Returns true if this device has a unique system UUID.

If this function returns false, system_uuid is undefined.

Returns: true if this device has a unique system UUID.

◆ hash_combine() [1/2]

void cugl::hashtool::hash_combine ( std::size_t & seed )

inline

Provides the base case for a recursive hash_combiner.

A hash_combiner is used to produce a hash function on a user-defined type by recursively combining the (built-in) hash functions for the individual attributes. It does this by performing recursion over variadic templates.

This is function is the base (untemplated) version. It does nothing by itself, and should never be called directly.

This function is taken from

 https://stackoverflow.com/questions/2590677/how-do-i-combine-hash-values-in-c0x

Parameters

seed	The combination seed (communicates recursive depth)

◆ hash_combine() [2/2]

template<typename T , typename... Rest>

void cugl::hashtool::hash_combine	(	std::size_t &	seed,
		const T &	v,
		Rest...	rest
	)

inline

Provides the recursive case for a recursive hash_combiner.

A hash_combiner is used to produce a hash function on a user-defined type by recursively combining the (built-in) hash functions for the individual attributes. It does this by performing recursion over variadic templates.

This is function is the recursive (templated) version. To use it, call it on all your attributes using a seed of 0.

This function is taken from

 https://stackoverflow.com/questions/2590677/how-do-i-combine-hash-values-in-c0x

Parameters

seed	The combination seed (communicates recursive depth)
v	The first attribute to combine
rest	The remaining attributes to combine

◆ system_uuid()

std::string cugl::hashtool::system_uuid ( )

Returns a UUID representing this device.

This creates a Version 5 UUID hashed upon a system identifer. This system identifier is, at best, guaranteed to be a "vendor id". That means that can identify this device across all applications deployed by a single developer/company but cannot be used cross developers. It can also be lost if the user uninstalls and reinstalls the application.

As a Version 5 uuid, this is a 32 character hexadecimal string with dashes separating the characters into groups of 8-4-4-4-12 (as well as supporting Version 5 markers).

Returns: a UUID representing this device.