#ifndef SPROUT_RANDOM_XOR_COMBINE_HPP
#define SPROUT_RANDOM_XOR_COMBINE_HPP

#include <ios>
#include <istream>
#include <sprout/config.hpp>
#include <sprout/random/random_result.hpp>
#include HDR_ALGORITHM_SSCRISK_CEL_OR_SPROUT

namespace sprout {
	namespace random {
		//
		// xor_combine_engine
		//
		template<typename URNG1, int s1, typename URNG2, int s2>
		class xor_combine_engine {
		public:
			typedef URNG1 base1_type;
			typedef URNG2 base2_type;
			typedef typename base1_type::result_type result_type;
		public:
			SPROUT_STATIC_CONSTEXPR int shift1 = s1;
			SPROUT_STATIC_CONSTEXPR int shift2 = s2;
		private:
			base1_type rng1_;
			base2_type rng2_;
		private:
			template<typename Random1, typename Random2>
			SPROUT_CONSTEXPR sprout::random::random_result<xor_combine_engine> generate(Random1 const& rnd1, Random2 const& rnd2) const {
				return sprout::random::random_result<xor_combine_engine>(
					(rnd1.result() << s1) ^ (rnd2.result() << s2),
					xor_combine_engine(
						rnd1.engine(),
						rnd2.engine()
						)
					);
			}
		public:
			SPROUT_CONSTEXPR xor_combine_engine()
				: rng1_()
				, rng2_()
			{}
			explicit SPROUT_CONSTEXPR xor_combine_engine(result_type const& seed)
				: rng1_(seed)
				, rng2_(seed)
			{}
			SPROUT_CONSTEXPR xor_combine_engine(base1_type const& rng1, base2_type const& rng2)
				: rng1_(rng1)
				, rng2_(rng2)
			{}
			SPROUT_CONSTEXPR result_type min() const {
				return NS_SSCRISK_CEL_OR_SPROUT::min(rng1_.min(), rng2_.min());
			}
			SPROUT_CONSTEXPR result_type max() const {
				return NS_SSCRISK_CEL_OR_SPROUT::max(rng1_.max(), rng2_.max());
			}
			SPROUT_CONSTEXPR sprout::random::random_result<xor_combine_engine> operator()() const {
				return generate(rng1_(), rng2_());
			}
			friend SPROUT_CONSTEXPR bool operator==(xor_combine_engine const& lhs, xor_combine_engine const& rhs) {
				return lhs.rng1_ == rhs.rng1_ && lhs.rng2_ == rhs.rng2_;
			}
			friend SPROUT_CONSTEXPR bool operator!=(xor_combine_engine const& lhs, xor_combine_engine const& rhs) {
				return !(lhs == rhs);
			}
			template<typename Elem, typename Traits>
			friend std::basic_istream<Elem, Traits>& operator>>(
				std::basic_istream<Elem, Traits>& lhs,
				xor_combine_engine& rhs
				)
			{
				return lhs >> rhs.rng1_ >> std::ws >> rhs.rng2_;
			}
			template<typename Elem, typename Traits>
			friend std::basic_ostream<Elem, Traits>& operator<<(
				std::basic_ostream<Elem, Traits>& lhs,
				xor_combine_engine const& rhs
				)
			{
				return lhs << rhs.rng1_ << ' ' << rhs.rng2_;
			}
		};
		template<typename URNG1, int s1, typename URNG2, int s2>
		SPROUT_CONSTEXPR int sprout::random::xor_combine_engine<URNG1, s1, URNG2, s2>::shift1;
		template<typename URNG1, int s1, typename URNG2, int s2>
		SPROUT_CONSTEXPR int sprout::random::xor_combine_engine<URNG1, s1, URNG2, s2>::shift2;
	} // namespace random
} // namespace sprout

#endif // #ifndef SPROUT_RANDOM_XOR_COMBINE_HPP