Src/Algebra/Monoid/ReverseOrder.hpp

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• Last update: 2025-08-04 20:48:18+09:00
• Include: #include "Src/Algebra/Monoid/ReverseOrder.hpp"

Depends on

• Src/Algebra/Monoid/MonoidConcept.hpp
• Src/Algebra/Semigroup/SemigroupConcept.hpp

Verified with

• Test/AOJ/0478.test.cpp
• Test/AOJ/2450.test.cpp

Code

#pragma once

#include "./MonoidConcept.hpp"

namespace zawa {

template <concepts::Monoid M>
struct ReverseOrder {

    using Element = M::Element;
    
    static Element identity() {
        return M::identity();
    }

    static Element operation(const Element& L, const Element& R) {
        return M::operation(R, L);
    }

};

} // namespace zawa

#line 2 "Src/Algebra/Monoid/ReverseOrder.hpp"

#line 2 "Src/Algebra/Monoid/MonoidConcept.hpp"

#line 2 "Src/Algebra/Semigroup/SemigroupConcept.hpp"

#include <concepts>

namespace zawa {

namespace concepts {

template <class T>
concept Semigroup = requires {
    typename T::Element;
    { T::operation(std::declval<typename T::Element>(), std::declval<typename T::Element>()) } -> std::same_as<typename T::Element>;
};

} // namespace concepts

} // namespace zawa
#line 4 "Src/Algebra/Monoid/MonoidConcept.hpp"

#line 6 "Src/Algebra/Monoid/MonoidConcept.hpp"

namespace zawa {

namespace concepts {

template <class T>
concept Identitiable = requires {
    typename T::Element;
    { T::identity() } -> std::same_as<typename T::Element>;
};

template <class T>
concept Monoid = Semigroup<T> and Identitiable<T>;

} // namespace

} // namespace zawa
#line 4 "Src/Algebra/Monoid/ReverseOrder.hpp"

namespace zawa {

template <concepts::Monoid M>
struct ReverseOrder {

    using Element = M::Element;
    
    static Element identity() {
        return M::identity();
    }

    static Element operation(const Element& L, const Element& R) {
        return M::operation(R, L);
    }

};

} // namespace zawa

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