lidavidm commented on a change in pull request #10726:
URL: https://github.com/apache/arrow/pull/10726#discussion_r670696529
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File path: cpp/src/arrow/util/enum.h
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@@ -43,68 +42,51 @@ constexpr bool CaseInsensitiveEquals(util::string_view l,
util::string_view r) {
return l.size() == r.size() && CaseInsensitiveEquals(l.data(), r.data(),
l.size());
}
-constexpr const char* SkipWhitespace(const char* raw) {
- return *raw == '\0' || !IsSpace(*raw) ? raw : SkipWhitespace(raw + 1);
-}
+} // namespace internal
-constexpr const char* SkipNonWhitespace(const char* raw) {
- return *raw == '\0' || IsSpace(*raw) ? raw : SkipNonWhitespace(raw + 1);
-}
+template <int N>
+struct EnumStrings {
+ template <int M>
+ static constexpr bool assert_count() {
+ static_assert(M == N, "Incorrect number of enum strings provided");
+ return false;
+ }
-constexpr size_t TokenSize(const char* token_start) {
- return SkipNonWhitespace(token_start) - token_start;
-}
+ template <typename... Strs>
+ constexpr EnumStrings(const Strs&... strs) // NOLINT runtime/explicit
+ : dummy_{assert_count<sizeof...(Strs)>()},
strings_{util::string_view(strs)...} {}
-constexpr size_t NextTokenStart(const char* raw, size_t token_start) {
- return SkipWhitespace(SkipNonWhitespace(raw + token_start)) - raw;
-}
+ constexpr int GetIndex(util::string_view repr, int i = 0) const {
+ return i == N ? -1
+ : internal::CaseInsensitiveEquals(strings_[i], repr)
+ ? i
+ : GetIndex(repr, i + 1);
+ }
-template <typename Raw, size_t... Offsets>
-struct EnumTypeImpl {
- static constexpr int kSize = sizeof...(Offsets);
+ using value_type = util::string_view;
+ using const_iterator = const util::string_view*;
- static constexpr util::string_view kValueStrs[sizeof...(Offsets)] = {
- {Raw::kValues + Offsets, TokenSize(Raw::kValues + Offsets)}...};
+ constexpr int size() const { return N; }
+ constexpr const util::string_view* data() const { return strings_; }
+ constexpr const_iterator begin() const { return data(); }
+ constexpr const_iterator end() const { return begin() + size(); }
+ constexpr util::string_view operator[](int i) const { return strings_[i]; }
- static constexpr int GetIndex(util::string_view repr, int i = 0) {
- return i == kSize
- ? -1
- : CaseInsensitiveEquals(kValueStrs[i], repr) ? i :
GetIndex(repr, i + 1);
- }
+ bool dummy_;
+ util::string_view strings_[N]; // NOLINT modernize
Review comment:
We can't use std::array since its methods aren't constexpr until C++17?
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