120 lines
3.5 KiB
C++
120 lines
3.5 KiB
C++
// Boost random_generator.hpp header file ----------------------------------------------//
|
|
|
|
// Copyright 2010 Andy Tompkins.
|
|
// Distributed under the Boost Software License, Version 1.0. (See
|
|
// accompanying file LICENSE_1_0.txt or copy at
|
|
// http://www.boost.org/LICENSE_1_0.txt)
|
|
|
|
#ifndef BOOST_UUID_RANDOM_GENERATOR_HPP
|
|
#define BOOST_UUID_RANDOM_GENERATOR_HPP
|
|
|
|
#include <boost/uuid/uuid.hpp>
|
|
#include <boost/uuid/seed_rng.hpp>
|
|
#include <boost/random/uniform_int.hpp>
|
|
#include <boost/random/variate_generator.hpp>
|
|
#include <boost/random/mersenne_twister.hpp>
|
|
#include <boost/assert.hpp>
|
|
#include <boost/shared_ptr.hpp>
|
|
#include <limits>
|
|
|
|
namespace boost {
|
|
namespace uuids {
|
|
|
|
// generate a random-based uuid
|
|
template <typename UniformRandomNumberGenerator>
|
|
class basic_random_generator {
|
|
private:
|
|
typedef uniform_int<unsigned long> distribution_type;
|
|
typedef variate_generator<UniformRandomNumberGenerator*, distribution_type> generator_type;
|
|
|
|
struct null_deleter
|
|
{
|
|
void operator()(void const *) const {}
|
|
};
|
|
|
|
public:
|
|
typedef uuid result_type;
|
|
|
|
// default constructor creates the random number generator
|
|
basic_random_generator()
|
|
: pURNG(new UniformRandomNumberGenerator)
|
|
, generator
|
|
( pURNG.get()
|
|
, distribution_type
|
|
( (std::numeric_limits<unsigned long>::min)()
|
|
, (std::numeric_limits<unsigned long>::max)()
|
|
)
|
|
)
|
|
{
|
|
// seed the random number generator
|
|
detail::seed(*pURNG);
|
|
}
|
|
|
|
// keep a reference to a random number generator
|
|
// don't seed a given random number generator
|
|
explicit basic_random_generator(UniformRandomNumberGenerator& gen)
|
|
: pURNG(&gen, null_deleter())
|
|
, generator
|
|
( pURNG.get()
|
|
, distribution_type
|
|
( (std::numeric_limits<unsigned long>::min)()
|
|
, (std::numeric_limits<unsigned long>::max)()
|
|
)
|
|
)
|
|
{}
|
|
|
|
// keep a pointer to a random number generator
|
|
// don't seed a given random number generator
|
|
explicit basic_random_generator(UniformRandomNumberGenerator* pGen)
|
|
: pURNG(pGen, null_deleter())
|
|
, generator
|
|
( pURNG.get()
|
|
, distribution_type
|
|
( (std::numeric_limits<unsigned long>::min)()
|
|
, (std::numeric_limits<unsigned long>::max)()
|
|
)
|
|
)
|
|
{
|
|
BOOST_ASSERT(pURNG);
|
|
}
|
|
|
|
uuid operator()()
|
|
{
|
|
uuid u;
|
|
|
|
int i=0;
|
|
unsigned long random_value = generator();
|
|
for (uuid::iterator it=u.begin(); it!=u.end(); ++it, ++i) {
|
|
if (i==sizeof(unsigned long)) {
|
|
random_value = generator();
|
|
i = 0;
|
|
}
|
|
|
|
// static_cast gets rid of warnings of converting unsigned long to boost::uint8_t
|
|
*it = static_cast<uuid::value_type>((random_value >> (i*8)) & 0xFF);
|
|
}
|
|
|
|
// set variant
|
|
// must be 0b10xxxxxx
|
|
*(u.begin()+8) &= 0xBF;
|
|
*(u.begin()+8) |= 0x80;
|
|
|
|
// set version
|
|
// must be 0b0100xxxx
|
|
*(u.begin()+6) &= 0x4F; //0b01001111
|
|
*(u.begin()+6) |= 0x40; //0b01000000
|
|
|
|
return u;
|
|
}
|
|
|
|
private:
|
|
shared_ptr<UniformRandomNumberGenerator> pURNG;
|
|
generator_type generator;
|
|
};
|
|
|
|
typedef basic_random_generator<mt19937> random_generator;
|
|
|
|
}} // namespace boost::uuids
|
|
|
|
#endif //BOOST_UUID_RANDOM_GENERATOR_HPP
|