[GitHub] [arrow] wesm commented on a change in pull request #7357: ARROW-9100: [C++] Add ascii_lower kernel

[GitBox <gi...@apache.org>]

wesm commented on a change in pull request #7357:
URL: https://github.com/apache/arrow/pull/7357#discussion_r438827531



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File path: cpp/src/arrow/compute/kernels/scalar_string.cc
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@@ -48,6 +48,16 @@ struct AsciiUpper {
   }
 };
 
+struct AsciiLower {
+  template <typename... Ignored>
+  static std::string Call(KernelContext*, const util::string_view& val) {
+    std::string result = val.to_string();
+    std::transform(result.begin(), result.end(), result.begin(),
+                   [](unsigned char c) { return std::tolower(c); });

Review comment:
       Note that I used `std::toupper` _just_ for illustration purposes, not because I thought it was the correct way to implement the kernel. 




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