GH-38874: [C++][Parquet] Minor: making parquet TypedComparator operat…

…ion as const method (#38875) ### Rationale for this change `parquet::TypedComparator<DType>` is not const method, which should be const ### What changes are included in this PR? Change `Compare`, `GetMinMax`, `GetMinMaxSpaced` to const ### Are these changes tested? No ### Are there any user-facing changes? No * Closes: #38874 Authored-by: mwish <maplewish117@gmail.com> Signed-off-by: mwish <maplewish117@gmail.com>
apache · Nov 28, 2023 · c614014 · c614014
1 parent 7cdb768
commit c614014
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Showing 2 changed files with 11 additions and 11 deletions.
diff --git a/cpp/src/parquet/statistics.cc b/cpp/src/parquet/statistics.cc
@@ -438,9 +438,9 @@ class TypedComparatorImpl
     return Helper::Compare(type_length_, a, b);
   }
 
-  bool Compare(const T& a, const T& b) override { return CompareInline(a, b); }
+  bool Compare(const T& a, const T& b) const override { return CompareInline(a, b); }
 
-  std::pair<T, T> GetMinMax(const T* values, int64_t length) override {
+  std::pair<T, T> GetMinMax(const T* values, int64_t length) const override {
     DCHECK_GT(length, 0);
 
     T min = Helper::DefaultMin();
@@ -457,7 +457,7 @@ class TypedComparatorImpl
 
   std::pair<T, T> GetMinMaxSpaced(const T* values, int64_t length,
                                   const uint8_t* valid_bits,
-                                  int64_t valid_bits_offset) override {
+                                  int64_t valid_bits_offset) const override {
     DCHECK_GT(length, 0);
 
     T min = Helper::DefaultMin();
@@ -477,7 +477,7 @@ class TypedComparatorImpl
     return {min, max};
   }
 
-  std::pair<T, T> GetMinMax(const ::arrow::Array& values) override {
+  std::pair<T, T> GetMinMax(const ::arrow::Array& values) const override {
     ParquetException::NYI(values.type()->ToString());
   }
 
@@ -491,7 +491,7 @@ class TypedComparatorImpl
 template <>
 std::pair<int32_t, int32_t>
 TypedComparatorImpl</*is_signed=*/false, Int32Type>::GetMinMax(const int32_t* values,
-                                                               int64_t length) {
+                                                               int64_t length) const {
   DCHECK_GT(length, 0);
 
   const uint32_t* unsigned_values = reinterpret_cast<const uint32_t*>(values);
@@ -537,13 +537,13 @@ std::pair<ByteArray, ByteArray> GetMinMaxBinaryHelper(
 
 template <>
 std::pair<ByteArray, ByteArray> TypedComparatorImpl<true, ByteArrayType>::GetMinMax(
-    const ::arrow::Array& values) {
+    const ::arrow::Array& values) const {
   return GetMinMaxBinaryHelper<true>(*this, values);
 }
 
 template <>
 std::pair<ByteArray, ByteArray> TypedComparatorImpl<false, ByteArrayType>::GetMinMax(
-    const ::arrow::Array& values) {
+    const ::arrow::Array& values) const {
   return GetMinMaxBinaryHelper<false>(*this, values);
 }
 

diff --git a/cpp/src/parquet/statistics.h b/cpp/src/parquet/statistics.h
@@ -73,16 +73,16 @@ class TypedComparator : public Comparator {
 
   /// \brief Scalar comparison of two elements, return true if first
   /// is strictly less than the second
-  virtual bool Compare(const T& a, const T& b) = 0;
+  virtual bool Compare(const T& a, const T& b) const = 0;
 
   /// \brief Compute maximum and minimum elements in a batch of
   /// elements without any nulls
-  virtual std::pair<T, T> GetMinMax(const T* values, int64_t length) = 0;
+  virtual std::pair<T, T> GetMinMax(const T* values, int64_t length) const = 0;
 
   /// \brief Compute minimum and maximum elements from an Arrow array. Only
   /// valid for certain Parquet Type / Arrow Type combinations, like BYTE_ARRAY
   /// / arrow::BinaryArray
-  virtual std::pair<T, T> GetMinMax(const ::arrow::Array& values) = 0;
+  virtual std::pair<T, T> GetMinMax(const ::arrow::Array& values) const = 0;
 
   /// \brief Compute maximum and minimum elements in a batch of
   /// elements with accompanying bitmap indicating which elements are
@@ -96,7 +96,7 @@ class TypedComparator : public Comparator {
   /// the first element in the sequence
   virtual std::pair<T, T> GetMinMaxSpaced(const T* values, int64_t length,
                                           const uint8_t* valid_bits,
-                                          int64_t valid_bits_offset) = 0;
+                                          int64_t valid_bits_offset) const = 0;
 };
 
 /// \brief Typed version of Comparator::Make