when.hpp

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#pragma once
 
#include "indep/common/typedef.hpp"
#include "indep/def/_nout.hpp"
#include "indep/helper/tmay.hpp"
#include "indep/helper/typeTrait.hpp"
#include "indep/macro/byeolMeta.hpp"
#include "indep/macro/declThis.hpp"
#include <cstdlib>
#include <functional>
#include <utility>
 
namespace by {
 
#define __WHEN_OBJECT__ __indep_when__
 
    class _nout __WHEN_OBJECT__ {
        BY(ME(__WHEN_OBJECT__))
 
    public:
        static const me& get();
 
        template <typename R> R& ret([[maybe_unused]] R& r) const { return r; }
 
        template <typename R> R* ret([[maybe_unused]] R* r) const { return r; }
 
        template <typename R> R&& ret([[maybe_unused]] R&& r) const { return std::move(r); }
 
        const me& run(const std::function<void(void)>& closure) const;
 
        void ret() const;
 
        template <typename T> tmay<T> retMay() const { return tmay<T>(); }
 
        template <typename T, typename... Ts> tmay<T> retMay(Ts... args) const { return tmay<T>(args...); }
 
        void crash() const;
 
        template <typename R> R& crash([[maybe_unused]] R& r) const {
            abort();
            return r;
        }
 
        template <typename R> R&& crash([[maybe_unused]] R&& r) const {
            abort();
            return std::move(r);
        }
    };
 
#define BY_WHEN ::by::__WHEN_OBJECT__::get()
 
#define __WHEN_POSTFIX__ return BY_WHEN
#define WHEN(condition) \
    if(condition) __WHEN_POSTFIX__
#define WHEN_NUL_1(v1) \
    if(nul(v1)) __WHEN_POSTFIX__
#define WHEN_NUL_2(v1, v2) \
    if(nul(v1) || nul(v2)) __WHEN_POSTFIX__
#define WHEN_NUL_3(v1, v2, v3) \
    if(nul(v1) || nul(v2) || nul(v3)) __WHEN_POSTFIX__
#define WHEN_NUL_4(v1, v2, v3, v4) \
    if(nul(v1) || nul(v2) || nul(v3) || nul(v4)) __WHEN_POSTFIX__
#define WHEN_NUL_5(v1, v2, v3, v4, v5) \
    if(nul(v1) || nul(v2) || nul(v3) || nul(v4) || nul(v5)) __WHEN_POSTFIX__
#define WHEN_NUL_6(v1, v2, v3, v4, v5, v6) \
    if(nul(v1) || nul(v2) || nul(v3) || nul(v4) || nul(v5) || nul(v6)) __WHEN_POSTFIX__
#define WHEN_NUL(...) BY_OVERLOAD(WHEN_NUL, __VA_ARGS__)
 
} // namespace by