Function Join

src/util/string.h:45–54

 */
template <typename T, typename BaseType, typename UnaryOp>
auto Join(const std::vector<T>& list, const BaseType& separator, UnaryOp unary_op)
    -> decltype(unary_op(list.at(0)))
{
    decltype(unary_op(list.at(0))) ret;
    for (size_t i = 0; i < list.size(); ++i) {
        if (i > 0) ret += separator;
        ret += unary_op(list.at(i));
    }
    return ret;
}

template <typename T>
T Join(const std::vector<T>& list, const T& separator)