jding-xyz commented on code in PR #149:
URL: https://github.com/apache/arrow-swift/pull/149#discussion_r2992849833
##########
Sources/Arrow/ArrowWriter.swift:
##########
@@ -178,16 +185,23 @@ public class ArrowWriter { // swiftlint:disable:this
type_body_length
fbb: inout FlatBufferBuilder) {
for index in (0 ..< fields.count).reversed() {
let column = columns[index]
- let fieldNode =
- org_apache_arrow_flatbuf_FieldNode(length:
Int64(column.length),
- nullCount:
Int64(column.nullCount))
- offsets.append(fbb.create(struct: fieldNode))
+ // FlatBuffer vectors use prepend semantics: last-written element
becomes
+ // the first when read. Arrow IPC requires depth-first pre-order
(parent
+ // before children), so children must be written before their
parent here.
if let nestedType = column.type as? ArrowTypeStruct {
let nestedArray = column.array as? NestedArray
if let nestedFields = nestedArray?.fields {
writeFieldNodes(nestedType.fields, columns: nestedFields,
offsets: &offsets, fbb: &fbb)
}
+ } else if let listType = column.type as? ArrowTypeList {
+ if let nestedArray = column.array as? NestedArray, let
valuesHolder = nestedArray.values {
+ writeFieldNodes([listType.elementField], columns:
[valuesHolder], offsets: &offsets, fbb: &fbb)
+ }
}
+ let fieldNode =
+ org_apache_arrow_flatbuf_FieldNode(length:
Int64(column.length),
+ nullCount:
Int64(column.nullCount))
+ offsets.append(fbb.create(struct: fieldNode))
Review Comment:
Added testListInt32RBInMemoryToFromStream and
testListStructRBInMemoryToFromStream in IPCTests.
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