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// Copyright (c) 2020 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#ifndef BITCOIN_UTIL_REF_H
#define BITCOIN_UTIL_REF_H
#include <util/check.h>
#include <typeindex>
namespace util {
/**
* Type-safe dynamic reference.
*
* This implements a small subset of the functionality in C++17's std::any
* class, and can be dropped when the project updates to C++17
* (https://github.com/bitcoin/bitcoin/issues/16684)
*/
class Ref
{
public:
Ref() = default;
template<typename T> Ref(T& value) { Set(value); }
template<typename T> T& Get() const { CHECK_NONFATAL(Has<T>()); return *static_cast<T*>(m_value); }
template<typename T> void Set(T& value) { m_value = &value; m_type = std::type_index(typeid(T)); }
template<typename T> bool Has() const { return m_value && m_type == std::type_index(typeid(T)); }
void Clear() { m_value = nullptr; m_type = std::type_index(typeid(void)); }
private:
void* m_value = nullptr;
std::type_index m_type = std::type_index(typeid(void));
};
} // namespace util
#endif // BITCOIN_UTIL_REF_H
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