ext-boost/boost/range/algorithm/random_shuffle.hpp

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// Copyright Neil Groves 2009. Use, modification and
// distribution is subject to 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)
//
//
// For more information, see http://www.boost.org/libs/range/
//
#ifndef BOOST_RANGE_ALGORITHM_RANDOM_SHUFFLE_HPP_INCLUDED
#define BOOST_RANGE_ALGORITHM_RANDOM_SHUFFLE_HPP_INCLUDED
#include <boost/concept_check.hpp>
#include <boost/range/begin.hpp>
#include <boost/range/end.hpp>
#include <boost/range/concepts.hpp>
#include <algorithm>
#ifdef BOOST_NO_CXX98_RANDOM_SHUFFLE
#include <cstdlib>
#endif
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namespace boost
{
namespace range
{
namespace detail
{
#ifdef BOOST_NO_CXX98_RANDOM_SHUFFLE
// wrap std::rand as UniformRandomBitGenerator
struct wrap_rand
{
typedef unsigned int result_type;
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static BOOST_CONSTEXPR result_type (min)()
{
return 0;
}
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static BOOST_CONSTEXPR result_type (max)()
{
return RAND_MAX;
}
result_type operator()()
{
return std::rand();
}
};
template< class RandomIt >
inline void random_shuffle(RandomIt first, RandomIt last)
{
std::shuffle(first, last, wrap_rand());
}
// wrap Generator as UniformRandomBitGenerator
template< class Generator >
struct wrap_generator
{
typedef unsigned int result_type;
static const int max_arg = ((0u - 1u) >> 2) + 1;
Generator& g;
wrap_generator(Generator& gen) : g(gen) {}
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static BOOST_CONSTEXPR result_type (min)()
{
return 0;
}
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static BOOST_CONSTEXPR result_type (max)()
{
return max_arg - 1;
}
result_type operator()()
{
return static_cast<result_type>(g(max_arg));
}
};
template< class RandomIt, class Generator >
inline void random_shuffle(RandomIt first, RandomIt last, Generator& gen)
{
std::shuffle(first, last, wrap_generator< Generator >(gen));
}
#else
using std::random_shuffle;
#endif
} // namespace detail
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/// \brief template function random_shuffle
///
/// range-based version of the random_shuffle std algorithm
///
/// \pre RandomAccessRange is a model of the RandomAccessRangeConcept
/// \pre Generator is a model of the UnaryFunctionConcept
template<class RandomAccessRange>
inline RandomAccessRange& random_shuffle(RandomAccessRange& rng)
{
BOOST_RANGE_CONCEPT_ASSERT(( RandomAccessRangeConcept<RandomAccessRange> ));
detail::random_shuffle(boost::begin(rng), boost::end(rng));
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return rng;
}
/// \overload
template<class RandomAccessRange>
inline const RandomAccessRange& random_shuffle(const RandomAccessRange& rng)
{
BOOST_RANGE_CONCEPT_ASSERT(( RandomAccessRangeConcept<const RandomAccessRange> ));
detail::random_shuffle(boost::begin(rng), boost::end(rng));
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return rng;
}
/// \overload
template<class RandomAccessRange, class Generator>
inline RandomAccessRange& random_shuffle(RandomAccessRange& rng, Generator& gen)
{
BOOST_RANGE_CONCEPT_ASSERT(( RandomAccessRangeConcept<RandomAccessRange> ));
detail::random_shuffle(boost::begin(rng), boost::end(rng), gen);
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return rng;
}
/// \overload
template<class RandomAccessRange, class Generator>
inline const RandomAccessRange& random_shuffle(const RandomAccessRange& rng, Generator& gen)
{
BOOST_RANGE_CONCEPT_ASSERT(( RandomAccessRangeConcept<const RandomAccessRange> ));
detail::random_shuffle(boost::begin(rng), boost::end(rng), gen);
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return rng;
}
} // namespace range
using range::random_shuffle;
} // namespace boost
#endif // include guard