data_structure/Suspension.hpp

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Last update: 2023-05-08 16:51:58+09:00
Include: #include "data_structure/Suspension.hpp"
Link: https://noshi91.github.io/Library/other/suspension.cpp

Required by

Verified with

test/data_structure/Persistent_Queue.test.cpp

Code

#pragma once

/*
    reference: https://noshi91.github.io/Library/other/suspension.cpp
*/

#include <functional>

#include <memory>

#include <utility>

#include <variant>


namespace ebi {

template <class T>
struct suspension : std::shared_ptr<std::variant<T, std::function<T()>>> {
    using value_type = T;
    using func_type = std::function<T()>;
    using node_type = std::variant<T, std::function<T()>>;
    using base_type = std::shared_ptr<node_type>;

  private:
    static T get(node_type &x) {
        if (x.index() != 0) {
            x = std::get<1>(x)();
        }
        return std::get<0>(x);
    }

  public:
    suspension(T x)
        : base_type(std::make_shared<node_type>(std::in_place_index<0>, x)) {}
    suspension(std::function<T()> f)
        : base_type(std::make_shared<node_type>(std::in_place_index<1>, f)) {}

    T force() const {
        return get(**this);
    }
};

}  // namespace ebi

#line 2 "data_structure/Suspension.hpp"

/*
    reference: https://noshi91.github.io/Library/other/suspension.cpp
*/

#include <functional>

#include <memory>

#include <utility>

#include <variant>


namespace ebi {

template <class T>
struct suspension : std::shared_ptr<std::variant<T, std::function<T()>>> {
    using value_type = T;
    using func_type = std::function<T()>;
    using node_type = std::variant<T, std::function<T()>>;
    using base_type = std::shared_ptr<node_type>;

  private:
    static T get(node_type &x) {
        if (x.index() != 0) {
            x = std::get<1>(x)();
        }
        return std::get<0>(x);
    }

  public:
    suspension(T x)
        : base_type(std::make_shared<node_type>(std::in_place_index<0>, x)) {}
    suspension(std::function<T()> f)
        : base_type(std::make_shared<node_type>(std::in_place_index<1>, f)) {}

    T force() const {
        return get(**this);
    }
};

}  // namespace ebi