// 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
