mirror of
https://github.com/bolero-MURAKAMI/Sprout
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110 lines
3.1 KiB
C++
110 lines
3.1 KiB
C++
#ifndef SPROUT_MATH_LCM_HPP
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#define SPROUT_MATH_LCM_HPP
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#include <climits>
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#include <limits>
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#include <sprout/config.hpp>
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#include <sprout/math/gcd.hpp>
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namespace sprout {
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namespace math {
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namespace detail {
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template<typename RingType>
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inline SPROUT_CONSTEXPR RingType
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lcm_euclidean_impl(RingType a, RingType b, RingType temp) {
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return temp != static_cast<RingType>(0) ? (a / temp * b)
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: static_cast<RingType>(0)
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;
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}
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template<typename RingType>
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inline SPROUT_CONSTEXPR RingType
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lcm_euclidean(RingType a, RingType b) {
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return sprout::math::detail::lcm_euclidean_impl(
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a, b, sprout::math::detail::gcd_euclidean(a, b)
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);
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}
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template<typename IntType>
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inline SPROUT_CONSTEXPR IntType
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lcm_integer_impl(IntType result) {
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return result < static_cast<IntType>(0) ? -result : result;
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}
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template<typename IntType>
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inline SPROUT_CONSTEXPR IntType
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lcm_integer(IntType const& a, IntType const& b) {
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return sprout::math::detail::lcm_integer_impl(
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sprout::math::detail::lcm_euclidean(a, b)
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);
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}
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template<typename T, bool IsSpecialized, bool IsSigned>
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struct lcm_optimal_evaluator_helper_t {
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public:
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SPROUT_CONSTEXPR T operator()(T const& a, T const& b) const {
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return sprout::math::detail::lcm_euclidean(a, b);
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}
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};
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template<typename T>
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struct lcm_optimal_evaluator_helper_t<T, true, true> {
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public:
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SPROUT_CONSTEXPR T operator()(T const& a, T const& b) const {
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return sprout::math::detail::lcm_integer(a, b);
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}
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};
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template<typename T>
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struct lcm_optimal_evaluator {
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public:
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SPROUT_CONSTEXPR T operator()(T const& a, T const& b) const {
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typedef std::numeric_limits<T> limits_type;
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typedef sprout::math::detail::lcm_optimal_evaluator_helper_t<
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T, limits_type::is_specialized, limits_type::is_signed
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> helper_type;
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return helper_type().operator()(a, b);
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}
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};
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template<typename T>
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inline SPROUT_CONSTEXPR T
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lcm_optimal(T const& a, T const& b) {
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return sprout::math::detail::lcm_optimal_evaluator<T>().operator()(a, b);
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}
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} // namespace detail
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//
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// lcm_evaluator
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//
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template<typename IntType = void>
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class lcm_evaluator {
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public:
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typedef IntType result_type;
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typedef IntType first_argument_type;
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typedef IntType second_argument_type;
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public:
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SPROUT_CONSTEXPR IntType
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operator()(IntType const& a, IntType const& b) const {
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return sprout::math::detail::lcm_optimal(a, b);
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}
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};
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template<>
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class lcm_evaluator<void> {
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public:
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template<typename IntType>
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SPROUT_CONSTEXPR IntType
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operator()(IntType const& a, IntType const& b) const {
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return sprout::math::detail::lcm_optimal(a, b);
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}
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};
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//
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// lcm
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//
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template<typename IntType>
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inline SPROUT_CONSTEXPR IntType
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lcm(IntType const& a, IntType const& b) {
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return sprout::math::lcm_evaluator<IntType>().operator()(a, b);
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}
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} // namespace math
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} // namespace boost
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#endif // SPROUT_MATH_LCM_HPP
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