[GitHub] [arrow] wesm commented on a change in pull request #7514: ARROW-6235: [R] Implement conversion from arrow::BinaryArray to R character vector

[GitBox <gi...@apache.org>]

wesm commented on a change in pull request #7514:
URL: https://github.com/apache/arrow/pull/7514#discussion_r445127367



##########
File path: r/src/array_from_vector.cpp
##########
@@ -915,6 +924,39 @@ class Time64Converter : public TimeConverter<Time64Type> {
   }
 };
 
+class BinaryVectorConverter : public VectorConverter {
+ public:
+  ~BinaryVectorConverter() {}
+
+  Status Init(ArrayBuilder* builder) {
+    typed_builder_ = checked_cast<BinaryBuilder*>(builder);
+    return Status::OK();
+  }
+
+  Status Ingest(SEXP obj) {
+    ARROW_RETURN_IF(TYPEOF(obj) != VECSXP, Status::RError("Expecting a list"));
+    R_xlen_t n = XLENGTH(obj);
+    for (R_xlen_t i = 0; i < n; i++) {
+      SEXP obj_i = VECTOR_ELT(obj, i);
+      if (Rf_isNull(obj_i)) {
+        RETURN_NOT_OK(typed_builder_->AppendNull());
+      } else {
+        ARROW_RETURN_IF(TYPEOF(obj_i) != RAWSXP,
+                        Status::RError("Expecting a raw vector"));
+        RETURN_NOT_OK(typed_builder_->Append(RAW(obj_i), XLENGTH(obj_i)));

Review comment:
       You could add a call to `typed_builder_->Reserve` before the loop for slightly better perf




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