// Copyright (c) 2019 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_VECTOR_H #define BITCOIN_UTIL_VECTOR_H #include <initializer_list> #include <type_traits> #include <vector> /** Construct a vector with the specified elements. * * This is preferable over the list initializing constructor of std::vector: * - It automatically infers the element type from its arguments. * - If any arguments are rvalue references, they will be moved into the vector * (list initialization always copies). */ template<typename... Args> inline std::vector<typename std::common_type<Args...>::type> Vector(Args&&... args) { std::vector<typename std::common_type<Args...>::type> ret; ret.reserve(sizeof...(args)); // The line below uses the trick from https://www.experts-exchange.com/articles/32502/None-recursive-variadic-templates-with-std-initializer-list.html (void)std::initializer_list<int>{(ret.emplace_back(std::forward<Args>(args)), 0)...}; return ret; } /** Concatenate two vectors, moving elements. */ template<typename V> inline V Cat(V v1, V&& v2) { v1.reserve(v1.size() + v2.size()); for (auto& arg : v2) { v1.push_back(std::move(arg)); } return v1; } /** Concatenate two vectors. */ template<typename V> inline V Cat(V v1, const V& v2) { v1.reserve(v1.size() + v2.size()); for (const auto& arg : v2) { v1.push_back(arg); } return v1; } #endif // BITCOIN_UTIL_VECTOR_H