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