Use std::array in level_comparison dispatch

Author: AntoinePrv

cpp/src/arrow/util/dispatch_internal.h

@@ -18,7 +18,6 @@
 #pragma once
 
 #include <utility>
-#include <vector>
 
 #include "arrow/status.h"
 #include "arrow/util/cpu_info.h"

cpp/src/parquet/level_comparison.cc

@@ -15,6 +15,8 @@
 // specific language governing permissions and limitations
 // under the License.
 
+#include <array>
+
 #include "parquet/level_comparison.h"
 
 #if defined(ARROW_HAVE_RUNTIME_AVX2)
@@ -25,8 +27,6 @@
 #include "parquet/level_comparison_inc.h"
 #undef PARQUET_IMPL_NAMESPACE
 
-#include <vector>
-
 #include "arrow/util/dispatch_internal.h"
 
 namespace parquet::internal {
@@ -40,25 +40,27 @@ using ::arrow::internal::DynamicDispatch;
 
 struct GreaterThanDynamicFunction {
   using FunctionType = decltype(&GreaterThanBitmap);
+  using Implementation = std::pair<DispatchLevel, FunctionType>;
 
-  static std::vector<std::pair<DispatchLevel, FunctionType>> implementations() {
-    return {{DispatchLevel::NONE, standard::GreaterThanBitmapImpl}
+  static constexpr auto implementations() {
+    return std::array{
+        Implementation{DispatchLevel::NONE, standard::GreaterThanBitmapImpl},
 #if defined(ARROW_HAVE_RUNTIME_AVX2)
-            ,
-            {DispatchLevel::AVX2, GreaterThanBitmapAvx2}
+        Implementation{DispatchLevel::AVX2, GreaterThanBitmapAvx2},
 #endif
     };
   }
 };
 
 struct MinMaxDynamicFunction {
   using FunctionType = decltype(&FindMinMax);
+  using Implementation = std::pair<DispatchLevel, FunctionType>;
 
-  static std::vector<std::pair<DispatchLevel, FunctionType>> implementations() {
-    return {{DispatchLevel::NONE, standard::FindMinMaxImpl}
+  static constexpr auto implementations() {
+    return std::array{
+        Implementation{DispatchLevel::NONE, standard::FindMinMaxImpl},
 #if defined(ARROW_HAVE_RUNTIME_AVX2)
-            ,
-            {DispatchLevel::AVX2, FindMinMaxAvx2}
+        Implementation{DispatchLevel::AVX2, FindMinMaxAvx2},
 #endif
     };
   }