Chris@16: // Boost random_generator.hpp header file  ----------------------------------------------//
Chris@16: 
Chris@16: // Copyright 2010 Andy Tompkins.
Chris@16: // Distributed under the Boost Software License, Version 1.0. (See
Chris@16: // accompanying file LICENSE_1_0.txt or copy at
Chris@16: // http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: #ifndef BOOST_UUID_RANDOM_GENERATOR_HPP
Chris@16: #define BOOST_UUID_RANDOM_GENERATOR_HPP
Chris@16: 
Chris@16: #include <boost/uuid/uuid.hpp>
Chris@16: #include <boost/uuid/seed_rng.hpp>
Chris@16: #include <boost/random/uniform_int.hpp>
Chris@16: #include <boost/random/variate_generator.hpp>
Chris@16: #include <boost/random/mersenne_twister.hpp>
Chris@16: #include <boost/assert.hpp>
Chris@16: #include <boost/shared_ptr.hpp>
Chris@16: #include <limits>
Chris@16: 
Chris@16: namespace boost {
Chris@16: namespace uuids {
Chris@16: 
Chris@16: // generate a random-based uuid
Chris@16: template <typename UniformRandomNumberGenerator>
Chris@16: class basic_random_generator {
Chris@16: private:
Chris@16:     typedef uniform_int<unsigned long> distribution_type;
Chris@16:     typedef variate_generator<UniformRandomNumberGenerator*, distribution_type> generator_type;
Chris@16: 
Chris@16:     struct null_deleter
Chris@16:     {
Chris@16:         void operator()(void const *) const {}
Chris@16:     };
Chris@16: 
Chris@16: public:
Chris@16:     typedef uuid result_type;
Chris@16:     
Chris@16:     // default constructor creates the random number generator
Chris@16:     basic_random_generator()
Chris@16:         : pURNG(new UniformRandomNumberGenerator)
Chris@16:         , generator
Chris@16:           ( pURNG.get()
Chris@16:           , distribution_type
Chris@16:             ( (std::numeric_limits<unsigned long>::min)()
Chris@16:             , (std::numeric_limits<unsigned long>::max)()
Chris@16:             )
Chris@16:           )
Chris@16:     {
Chris@16:         // seed the random number generator
Chris@16:         detail::seed(*pURNG);
Chris@16:     }
Chris@16:     
Chris@16:     // keep a reference to a random number generator
Chris@16:     // don't seed a given random number generator
Chris@16:     explicit basic_random_generator(UniformRandomNumberGenerator& gen)
Chris@16:         : pURNG(&gen, null_deleter())
Chris@16:         , generator
Chris@16:           ( pURNG.get()
Chris@16:           , distribution_type
Chris@16:             ( (std::numeric_limits<unsigned long>::min)()
Chris@16:             , (std::numeric_limits<unsigned long>::max)()
Chris@16:             )
Chris@16:           )
Chris@16:     {}
Chris@16:     
Chris@16:     // keep a pointer to a random number generator
Chris@16:     // don't seed a given random number generator
Chris@16:     explicit basic_random_generator(UniformRandomNumberGenerator* pGen)
Chris@16:         : pURNG(pGen, null_deleter())
Chris@16:         , generator
Chris@16:           ( pURNG.get()
Chris@16:           , distribution_type
Chris@16:             ( (std::numeric_limits<unsigned long>::min)()
Chris@16:             , (std::numeric_limits<unsigned long>::max)()
Chris@16:             )
Chris@16:           )
Chris@16:     {
Chris@16:         BOOST_ASSERT(pURNG);
Chris@16:     }
Chris@16:     
Chris@16:     uuid operator()()
Chris@16:     {
Chris@16:         uuid u;
Chris@16:         
Chris@16:         int i=0;
Chris@16:         unsigned long random_value = generator();
Chris@16:         for (uuid::iterator it=u.begin(); it!=u.end(); ++it, ++i) {
Chris@16:             if (i==sizeof(unsigned long)) {
Chris@16:                 random_value = generator();
Chris@16:                 i = 0;
Chris@16:             }
Chris@16: 
Chris@16: 			// static_cast gets rid of warnings of converting unsigned long to boost::uint8_t
Chris@16:             *it = static_cast<uuid::value_type>((random_value >> (i*8)) & 0xFF);
Chris@16:         }
Chris@16: 
Chris@16:         // set variant
Chris@16:         // must be 0b10xxxxxx
Chris@16:         *(u.begin()+8) &= 0xBF;
Chris@16:         *(u.begin()+8) |= 0x80;
Chris@16: 
Chris@16:         // set version
Chris@16:         // must be 0b0100xxxx
Chris@16:         *(u.begin()+6) &= 0x4F; //0b01001111
Chris@16:         *(u.begin()+6) |= 0x40; //0b01000000
Chris@16: 
Chris@16:         return u;
Chris@16:     }
Chris@16: 
Chris@16: private:
Chris@16:     shared_ptr<UniformRandomNumberGenerator> pURNG;
Chris@16:     generator_type generator;
Chris@16: };
Chris@16: 
Chris@16: typedef basic_random_generator<mt19937> random_generator;
Chris@16: 
Chris@16: }} // namespace boost::uuids
Chris@16: 
Chris@16: #endif //BOOST_UUID_RANDOM_GENERATOR_HPP