pitrou commented on a change in pull request #9643:
URL: https://github.com/apache/arrow/pull/9643#discussion_r595159935
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File path: cpp/src/arrow/util/vector.h
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@@ -81,5 +84,53 @@ std::vector<T> FilterVector(std::vector<T> values,
Predicate&& predicate) {
return values;
}
+/// \brief Like MapVector, but where the function can fail.
+template <typename Fn, typename From = internal::call_traits::argument_type<0,
Fn>,
+ typename To = typename
internal::call_traits::return_type<Fn>::ValueType>
+Result<std::vector<To>> MaybeMapVector(Fn&& map, const std::vector<From>& src)
{
+ std::vector<To> out;
+ out.reserve(src.size());
+ ARROW_RETURN_NOT_OK(
+ MaybeTransform(src.begin(), src.end(), std::back_inserter(out), map));
+ return out;
+}
+
+template <typename Fn, typename From = internal::call_traits::argument_type<0,
Fn>,
+ typename To = typename internal::call_traits::return_type<Fn>>
+std::vector<To> MapVector(Fn&& map, const std::vector<From>& source) {
+ std::vector<To> out;
+ out.reserve(source.size());
+ std::transform(source.begin(), source.end(), std::back_inserter(out), map);
+ return out;
+}
+
+template <typename T>
+std::vector<T> FlattenVectors(const std::vector<std::vector<T>>& vecs) {
+ std::size_t sum = 0;
+ for (const auto& vec : vecs) {
+ sum += vec.size();
+ }
+ std::vector<T> out;
+ out.reserve(sum);
+ for (const auto& vec : vecs) {
+ out.insert(out.end(), vec.begin(), vec.end());
+ }
+ return out;
+}
+
+template <typename T>
+Result<std::vector<T>> UnwrapOrRaise(std::vector<Result<T>> results) {
Review comment:
I think it's enough to take `std::vector<Result<T>>&& results`. No copy
is done of the vector itself, we're just moving its individual elements.
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