Another solution is to use boost::transform_iterator
. The benefit is that you can pass iterators to the container constructor. That avoids memory reallocations compared to when using std::back_inserter
or having to call reserve
or resize
on the destination. All in one statement:
std::vector<int> result(
boost::make_transform_iterator(std::begin(a), F)
, boost::make_transform_iterator(std::end(a), F)
);
You can achieve terser syntax though, like this:
std::vector<int> result(transform_range(a, F));
transform_range
implementation:
template<class Iterator>
struct AutoSequence
{
Iterator const beg_, end_;
template<class T>
operator std::vector<T>() const {
return {beg_, end_};
}
};
template<class Function, class InSeq>
auto transform_range(InSeq const& in) -> AutoSequence<decltype(boost::make_transform_iterator<Function>(in.begin()))> {
return {
boost::make_transform_iterator<Function>(std::begin(in))
, boost::make_transform_iterator<Function>(std::end(in))
};
}
template<class Function, class InSeq>
auto transform_range(InSeq const& in, Function&& f) -> AutoSequence<decltype(boost::make_transform_iterator(in.begin(), f))> {
return {
boost::make_transform_iterator(std::begin(in), f)
, boost::make_transform_iterator(std::end(in), f)
};
}