edponce commented on code in PR #14827:
URL: https://github.com/apache/arrow/pull/14827#discussion_r1049002967
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cpp/src/arrow/util/reflection_internal.h:
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@@ -91,21 +92,260 @@ PropertyTuple<Properties...> MakeProperties(Properties...
props) {
return {std::make_tuple(props...)};
}
+/// Returns a string_view containing the name of a value.
+template <auto>
+constexpr std::string_view nameof(bool include_leading_k = false);
+
+/// Returns a string_view containing the (unqualified) name of a type.
+template <typename>
+constexpr std::string_view nameof();
+
+/// Returns a string_view containing the name of an enumeration member.
+template <typename Enum>
+constexpr std::string_view enum_name(Enum e, bool include_leading_k = false);
+
+/// Returns the enumeration member corresponding to name, or
+/// nullopt if name doesn't correspond to an enum member.
template <typename Enum>
-struct EnumTraits {};
+constexpr std::optional<Enum> enum_cast(std::string_view name);
+
+/// Returns the enumeration member corresponding to an integer, or
+/// nullopt if the integer doesn't correspond to an enum member.
+template <typename Enum, typename Int>
+constexpr auto enum_cast(Int i) ->
std::optional<decltype(static_cast<Enum>(i))>;
+
+namespace impl {
+template <auto V>
+constexpr std::string_view pretty_function() {
+#ifdef _MSC_VER
+ return __FUNCSIG__;
+#else
+ return __PRETTY_FUNCTION__;
+#endif
+}
+
+template <typename T>
+constexpr std::string_view pretty_function() {
+#ifdef _MSC_VER
+ return __FUNCSIG__;
+#else
+ return __PRETTY_FUNCTION__;
+#endif
+}
+
+constexpr auto kValueNamePrefixSuffix = [] {
+ size_t prefix{}, suffix{};
+
+ auto raw = pretty_function<2234527>();
+ if (prefix = raw.find("2234527"); prefix != std::string_view::npos) {
+ suffix = raw.size() - prefix - std::string_view{"2234527"}.size();
+ } else {
+ // some compilers render hexadecimal integer template arguments
+ raw = pretty_function<0x346243>();
+ prefix = raw.find("0x346243");
+ suffix = raw.size() - prefix - std::string_view{"0x346243"}.size();
+ }
+
+ return std::pair{prefix, suffix};
+}();
+
+constexpr auto kTypeNamePrefixSuffix = [] {
+ auto raw = pretty_function<double>();
+ size_t prefix = raw.find("double");
+ size_t suffix = raw.size() - prefix - std::string_view{"double"}.size();
+ return std::pair{prefix, suffix};
+}();
+
+/// std::array is not constexpr in all STL impls
+template <typename T, size_t N>
+class array {
+ public:
+ constexpr array() = default;
-template <typename Enum, Enum... Values>
-struct BasicEnumTraits {
- using CType = typename std::underlying_type<Enum>::type;
- using Type = typename CTypeTraits<CType>::ArrowType;
- static std::array<Enum, sizeof...(Values)> values() { return {Values...}; }
+ constexpr explicit array(const T* ptr) {
+ for (T& value : values_) {
+ value = *ptr++;
+ }
+ }
+
+ constexpr explicit array(const T (&arr)[N]) // NOLINT
+ : array{static_cast<const T*>(arr)} {}
+
+ [[nodiscard]] static constexpr size_t size() { return N; }
+ [[nodiscard]] constexpr const T* data() const { return values_; }
+ [[nodiscard]] constexpr T* data() { return values_; }
+ [[nodiscard]] constexpr const T* begin() const { return values_; }
+ [[nodiscard]] constexpr const T* end() const { return begin() + N; }
+ [[nodiscard]] constexpr const T& operator[](size_t i) const { return
begin()[i]; }
Review Comment:
why two different idioms for indexing?
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