mapleFU commented on code in PR #47524:
URL: https://github.com/apache/arrow/pull/47524#discussion_r2330713523
##########
cpp/src/arrow/csv/writer.cc:
##########
@@ -594,18 +604,39 @@ class CSVWriterImpl : public ipc::RecordBatchWriter {
// Only called once, as part of initialization
RETURN_NOT_OK(data_buffer_->Resize(CalculateHeaderSize(),
/*shrink_to_fit=*/false));
char* next = reinterpret_cast<char*>(data_buffer_->mutable_data());
+ int64_t no_quoting_count = 0;
for (int col = 0; col < schema_->num_fields(); ++col) {
- *next++ = '"';
- next = Escape(schema_->field(col)->name(), next);
- *next++ = '"';
+ const std::string& col_name = schema_->field(col)->name();
+ switch (options_.quoting_header) {
+ case QuotingStyle::None:
+ if (StopAtStructuralChar(reinterpret_cast<const
uint8_t*>(col_name.c_str()),
+ col_name.length(), options_.delimiter) ==
+ static_cast<int64_t>(col_name.length())) {
+ memcpy(next, col_name.data(), col_name.size());
+ next += col_name.size();
+ no_quoting_count += 1;
+ break;
+ }
+ [[fallthrough]];
+ default:
Review Comment:
Can we add missing two branches without default?
##########
cpp/src/arrow/csv/writer.cc:
##########
@@ -594,18 +604,39 @@ class CSVWriterImpl : public ipc::RecordBatchWriter {
// Only called once, as part of initialization
RETURN_NOT_OK(data_buffer_->Resize(CalculateHeaderSize(),
/*shrink_to_fit=*/false));
Review Comment:
Actually I don't know would calculateHeaderSize can bettering handle this
without a round of resize. But current also looks ok to me
##########
cpp/src/arrow/csv/options.h:
##########
@@ -188,6 +188,12 @@ struct ARROW_EXPORT WriteOptions {
/// Whether to write an initial header line with column names
bool include_header = true;
+ /// \brief Quoting style of header
+ ///
+ /// If `quoting_header` is `QuotingStyle::None`, then only write quotes when
a column
+ /// name contains structural characters. Otherwise, always quote column
names.
+ QuotingStyle quoting_header = QuotingStyle::AllValid;
Review Comment:
I see, this is because `QuotingStyle::Needed` is too relaxed now, which
makes every string generate a quote value ( Might for performance ). Personally
I think we can:
1. Return error when None is configed and has error
2. If Needed , follow None behavior now
3. Default AllValid, add quotes everywhere
Also cc @pitrou for idea
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