Line data    Source code

       1             : // Copyright (c) 2020 The Bitcoin Core developers
       2             : // Distributed under the MIT software license, see the accompanying
       3             : // file COPYING or http://www.opensource.org/licenses/mit-license.php.
       4             : 
       5             : #ifndef BITCOIN_UTIL_REF_H
       6             : #define BITCOIN_UTIL_REF_H
       7             : 
       8             : #include <util/check.h>
       9             : 
      10             : #include <typeindex>
      11             : 
      12             : namespace util {
      13             : 
      14             : /**
      15             :  * Type-safe dynamic reference.
      16             :  *
      17             :  * This implements a small subset of the functionality in C++17's std::any
      18             :  * class, and can be dropped when the project updates to C++17
      19             :  * (https://github.com/bitcoin/bitcoin/issues/16684)
      20             :  */
      21             : class Ref
      22             : {
      23             : public:
      24          10 :     Ref() = default;
      25       38272 :     template<typename T> Ref(T& value) { Set(value); }
      26       39997 :     template<typename T> T& Get() const { CHECK_NONFATAL(Has<T>()); return *static_cast<T*>(m_value); }
      27       19138 :     template<typename T> void Set(T& value) { m_value = &value; m_type = std::type_index(typeid(T)); }
      28       79991 :     template<typename T> bool Has() const { return m_value && m_type == std::type_index(typeid(T)); }
      29           1 :     void Clear() { m_value = nullptr; m_type = std::type_index(typeid(void)); }
      30             : 
      31             : private:
      32       19141 :     void* m_value = nullptr;
      33       19141 :     std::type_index m_type = std::type_index(typeid(void));
      34             : };
      35             : 
      36             : } // namespace util
      37             : 
      38             : #endif // BITCOIN_UTIL_REF_H