pitrou commented on a change in pull request #9643:
URL: https://github.com/apache/arrow/pull/9643#discussion_r598945898
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File path: cpp/src/arrow/util/stl_util_test.cc
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@@ -92,5 +93,66 @@ TEST(StlUtilTest, ArgSortPermute) {
ExpectSortPermutation({b, c, d, e, a, f}, {4, 0, 1, 2, 3, 5}, 2);
}
+TEST(StlUtilTest, VectorFlatten) {
+ std::vector<int> a{1, 2, 3};
+ std::vector<int> b{4, 5, 6};
+ std::vector<int> c{7, 8, 9};
+ std::vector<std::vector<int>> vecs{a, b, c};
+ auto actual = FlattenVectors(vecs);
+ std::vector<int> expected{1, 2, 3, 4, 5, 6, 7, 8, 9};
+ ASSERT_EQ(expected, actual);
+}
+
+TEST(StlUtilTest, VectorMap) {
+ std::vector<int> input{1, 2, 3};
+ std::vector<std::string> expected{"1", "2", "3"};
+ auto actual = MapVector([](int item) { return std::to_string(item); },
input);
Review comment:
How about:
```c++
template <typename Fn, typename From, typename
To=decltype(std::declval<Fn>()(std::declval<From>()))>
std::vector<To> MapVector(Fn&& map, const std::vector<From>& source) {
```
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