// Copyright Neil Groves 2009. Use, modification and
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// distribution is subject to the Boost Software License, Version
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// 1.0. (See 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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//
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//
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// For more information, see http://www.boost.org/libs/range/
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//
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#ifndef BOOST_RANGE_ALGORITHM_RANDOM_SHUFFLE_HPP_INCLUDED
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#define BOOST_RANGE_ALGORITHM_RANDOM_SHUFFLE_HPP_INCLUDED
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#include <boost/concept_check.hpp>
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#include <boost/range/begin.hpp>
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#include <boost/range/end.hpp>
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#include <boost/range/concepts.hpp>
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#include <algorithm>
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#ifdef BOOST_NO_CXX98_RANDOM_SHUFFLE
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#include <cstdlib>
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#endif
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namespace boost
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{
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namespace range
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{
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namespace detail
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{
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#ifdef BOOST_NO_CXX98_RANDOM_SHUFFLE
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// wrap std::rand as UniformRandomBitGenerator
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struct wrap_rand
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{
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typedef unsigned int result_type;
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static BOOST_CONSTEXPR result_type (min)()
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{
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return 0;
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}
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static BOOST_CONSTEXPR result_type (max)()
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{
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return RAND_MAX;
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}
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result_type operator()()
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{
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return std::rand();
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}
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};
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template< class RandomIt >
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inline void random_shuffle(RandomIt first, RandomIt last)
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{
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std::shuffle(first, last, wrap_rand());
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}
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// wrap Generator as UniformRandomBitGenerator
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template< class Generator >
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struct wrap_generator
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{
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typedef unsigned int result_type;
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static const int max_arg = ((0u - 1u) >> 2) + 1;
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Generator& g;
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wrap_generator(Generator& gen) : g(gen) {}
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static BOOST_CONSTEXPR result_type (min)()
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{
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return 0;
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}
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static BOOST_CONSTEXPR result_type (max)()
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{
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return max_arg - 1;
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}
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result_type operator()()
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{
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return static_cast<result_type>(g(max_arg));
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}
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};
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template< class RandomIt, class Generator >
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inline void random_shuffle(RandomIt first, RandomIt last, Generator& gen)
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{
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std::shuffle(first, last, wrap_generator< Generator >(gen));
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}
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#else
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using std::random_shuffle;
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#endif
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} // namespace detail
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/// \brief template function random_shuffle
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///
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/// range-based version of the random_shuffle std algorithm
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///
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/// \pre RandomAccessRange is a model of the RandomAccessRangeConcept
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/// \pre Generator is a model of the UnaryFunctionConcept
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template<class RandomAccessRange>
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inline RandomAccessRange& random_shuffle(RandomAccessRange& rng)
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{
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BOOST_RANGE_CONCEPT_ASSERT(( RandomAccessRangeConcept<RandomAccessRange> ));
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detail::random_shuffle(boost::begin(rng), boost::end(rng));
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return rng;
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}
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/// \overload
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template<class RandomAccessRange>
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inline const RandomAccessRange& random_shuffle(const RandomAccessRange& rng)
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{
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BOOST_RANGE_CONCEPT_ASSERT(( RandomAccessRangeConcept<const RandomAccessRange> ));
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detail::random_shuffle(boost::begin(rng), boost::end(rng));
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return rng;
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}
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/// \overload
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template<class RandomAccessRange, class Generator>
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inline RandomAccessRange& random_shuffle(RandomAccessRange& rng, Generator& gen)
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{
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BOOST_RANGE_CONCEPT_ASSERT(( RandomAccessRangeConcept<RandomAccessRange> ));
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detail::random_shuffle(boost::begin(rng), boost::end(rng), gen);
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return rng;
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}
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/// \overload
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template<class RandomAccessRange, class Generator>
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inline const RandomAccessRange& random_shuffle(const RandomAccessRange& rng, Generator& gen)
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{
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BOOST_RANGE_CONCEPT_ASSERT(( RandomAccessRangeConcept<const RandomAccessRange> ));
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detail::random_shuffle(boost::begin(rng), boost::end(rng), gen);
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return rng;
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}
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} // namespace range
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using range::random_shuffle;
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} // namespace boost
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#endif // include guard
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