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https://issues.apache.org/jira/browse/ARROW-2351?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16419940#comment-16419940
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ASF GitHub Bot commented on ARROW-2351:
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wesm commented on a change in pull request #1803: ARROW-2351 [C++]
StringBuilder::append(vector<string>...) not impleme…
URL: https://github.com/apache/arrow/pull/1803#discussion_r178207724
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File path: cpp/src/arrow/builder.cc
##########
@@ -1385,6 +1385,28 @@ const uint8_t* BinaryBuilder::GetValue(int64_t i,
int32_t* out_length) const {
StringBuilder::StringBuilder(MemoryPool* pool) : BinaryBuilder(utf8(), pool) {}
+Status StringBuilder::Append(const std::vector<std::string>& values,
+ uint8_t* null_bytes) {
+ std::size_t total_length = std::accumulate(
+ values.begin(), values.end(), 0ULL,
+ [](uint64_t sum, const std::string& str) { return sum + str.size(); });
Review comment:
Is using `std::accumulate` with a lambda the same speed as a for loop?
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> [C++] StringBuilder::append(vector<string>...) not implemented
> --------------------------------------------------------------
>
> Key: ARROW-2351
> URL: https://issues.apache.org/jira/browse/ARROW-2351
> Project: Apache Arrow
> Issue Type: Bug
> Components: C++
> Affects Versions: 0.9.0
> Reporter: Rares Vernica
> Priority: Major
> Labels: pull-request-available
> Fix For: 0.10.0
>
>
> For {{StringBuilder}} an {{append(vector<string>, uint8_t*)}} function is
> [declared|https://github.com/apache/arrow/blob/7b2c79765cf92760e1f8cca079159d9613b86412/cpp/src/arrow/builder.h#L721]
> and
> [documented|http://arrow.apache.org/docs/cpp/classarrow_1_1_string_builder.html#a59be34b5e11017a392b4ee019d90da3c]
> but it does not seem to be implemented.
> {code:java}
> undefined reference to `arrow::StringBuilder::Append(std::vector<std::string,
> std::allocator<std::string> > const&, unsigned char*)'
> collect2: error: ld returned 1 exit status
> {code}
> Also worth noting is that the similar function in {{NumericBuilder}} uses
> {{vector<bool>}} for the null values instead of {{uint8_t*}}. It might be
> worth making them consistent.
>
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