| // 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 |
| |
| 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; |
| |
| static BOOST_CONSTEXPR result_type (min)() |
| { |
| return 0; |
| } |
| |
| 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) {} |
| |
| static BOOST_CONSTEXPR result_type (min)() |
| { |
| return 0; |
| } |
| |
| 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 |
| |
| /// \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)); |
| 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)); |
| 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); |
| 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); |
| return rng; |
| } |
| |
| } // namespace range |
| using range::random_shuffle; |
| } // namespace boost |
| |
| #endif // include guard |