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#pragma once
#include "special_members.h"
#include <functional>
#include <map>
#include <memory>
#include <tuple>
template<typename Obj, typename... KeyParts> class Cache {
public:
using Ptr = std::shared_ptr<Obj>;
using Key = std::tuple<KeyParts...>;
Cache() = default;
virtual ~Cache() = default;
DEFAULT_MOVE(Cache);
NO_COPY(Cache);
[[nodiscard]] Ptr
get(const KeyParts &... keyparts)
{
auto key = std::tie(keyparts...);
if (auto e = cached.find(key); e != cached.end()) {
return e->second;
}
return cached.emplace(key, construct(keyparts...)).first->second;
}
[[nodiscard]] virtual Ptr
construct(const KeyParts &... keyparts) const
{
return std::make_shared<Obj>(keyparts...);
}
private:
std::map<Key, Ptr, std::less<>> cached;
};
// IWYU pragma: no_forward_declare Cache
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