private FieldWriter promoteToUnion() {
String name = vector.getField().getLastName();
TransferPair tp =
vector.getTransferPair(
vector.getField().getType().getMinorType().name().toLowerCase(), vector.getAllocator());
tp.transfer();
if (parentContainer != null) {
unionVector =
parentContainer.addOrGet(name, Types.optional(MinorType.UNION), UnionVector.class);
} else if (listVector != null) {
unionVector = listVector.promoteToUnion();
}
unionVector.addVector(tp.getTo());
writer = new UnionWriter(unionVector);
writer.setPosition(idx());
for (int i = 0; i < idx(); i++) {
unionVector.getMutator().setType(i, vector.getField().getType().getMinorType());
}
vector = null;
state = State.UNION;
return writer;
}
