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author | Russell Yanofsky <russ@yanofsky.org> | 2020-04-17 11:15:55 -0400 |
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committer | Russell Yanofsky <russ@yanofsky.org> | 2020-05-13 16:20:13 -0400 |
commit | 691c817b340d10e806dc3b1834d2a8fcc5e681fd (patch) | |
tree | 1488abd285cf8d1026ac735ef03b80311c767326 /src/util/ref.h | |
parent | 04c09553d89809cf6328679d7535ecaa0070485d (diff) | |
download | bitcoin-691c817b340d10e806dc3b1834d2a8fcc5e681fd.tar.xz |
Add util::Ref class as temporary alternative for c++17 std::any
This commit does not change behavior
Diffstat (limited to 'src/util/ref.h')
-rw-r--r-- | src/util/ref.h | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/src/util/ref.h b/src/util/ref.h new file mode 100644 index 0000000000..9685ea9fec --- /dev/null +++ b/src/util/ref.h @@ -0,0 +1,38 @@ +// 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 |