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1 : // Copyright (c) 2019 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 PIVX_UTIL_VECTOR_H 6 : #define PIVX_UTIL_VECTOR_H 7 : 8 : #include <initializer_list> 9 : #include <type_traits> 10 : #include <vector> 11 : 12 : /** Construct a vector with the specified elements. 13 : * 14 : * This is preferable over the list initializing constructor of std::vector: 15 : * - It automatically infers the element type from its arguments. 16 : * - If any arguments are rvalue references, they will be moved into the vector 17 : * (list initialization always copies). 18 : */ 19 : template<typename... Args> 20 814 : inline std::vector<typename std::common_type<Args...>::type> Vector(Args&&... args) 21 : { 22 814 : std::vector<typename std::common_type<Args...>::type> ret; 23 814 : ret.reserve(sizeof...(args)); 24 : // The line below uses the trick from https://www.experts-exchange.com/articles/32502/None-recursive-variadic-templates-with-std-initializer-list.html 25 814 : (void)std::initializer_list<int>{(ret.emplace_back(std::forward<Args>(args)), 0)...}; 26 814 : return ret; 27 : } 28 : 29 : /** Concatenate two vectors, moving elements. */ 30 : template<typename V> 31 1002 : inline V Cat(V v1, V&& v2) 32 : { 33 1002 : v1.reserve(v1.size() + v2.size()); 34 97247 : for (auto& arg : v2) { 35 96245 : v1.push_back(std::move(arg)); 36 : } 37 1002 : return v1; 38 : } 39 : 40 : /** Concatenate two vectors. */ 41 : template<typename V> 42 44773 : inline V Cat(V v1, const V& v2) 43 : { 44 44773 : v1.reserve(v1.size() + v2.size()); 45 3865685 : for (const auto& arg : v2) { 46 3820909 : v1.push_back(arg); 47 : } 48 44773 : return v1; 49 : } 50 : 51 : #endif // PIVX_UTIL_VECTOR_H