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// 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
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