public ValueVector visit()

in vector/src/main/java/org/apache/arrow/vector/util/VectorAppender.java [607:684]
54 lines of code
13 McCabe index (conditional complexity)

  public ValueVector visit(DenseUnionVector deltaVector, Void value) {
    // we only make sure that both vectors are union vectors.
    Preconditions.checkArgument(
        targetVector.getMinorType() == deltaVector.getMinorType(),
        "The vector to append must have the same type as the targetVector being appended");

    if (deltaVector.getValueCount() == 0) {
      return targetVector; // optimization, nothing to append, return
    }

    DenseUnionVector targetDenseUnionVector = (DenseUnionVector) targetVector;
    int newValueCount = targetVector.getValueCount() + deltaVector.getValueCount();

    // make sure there is enough capacity
    while (targetDenseUnionVector.getValueCapacity() < newValueCount) {
      targetDenseUnionVector.reAlloc();
    }

    // append type buffers
    MemoryUtil.copyMemory(
        deltaVector.getTypeBuffer().memoryAddress(),
        targetDenseUnionVector.getTypeBuffer().memoryAddress() + targetVector.getValueCount(),
        deltaVector.getValueCount());

    // append offset buffers
    for (int i = 0; i < deltaVector.getValueCount(); i++) {
      byte typeId = deltaVector.getTypeId(i);
      ValueVector targetChildVector = targetDenseUnionVector.getVectorByType(typeId);
      int offsetBase = targetChildVector == null ? 0 : targetChildVector.getValueCount();
      int deltaOffset = deltaVector.getOffset(i);
      long index = (long) (targetVector.getValueCount() + i) * DenseUnionVector.OFFSET_WIDTH;

      targetVector.getOffsetBuffer().setInt(index, offsetBase + deltaOffset);
    }

    // append child vectors
    for (int i = 0; i <= Byte.MAX_VALUE; i++) {
      ValueVector targetChildVector = targetDenseUnionVector.getVectorByType((byte) i);
      ValueVector deltaChildVector = deltaVector.getVectorByType((byte) i);

      if (targetChildVector == null && deltaChildVector == null) {
        // the type id is not registered in either vector, we are done.
        continue;
      } else if (targetChildVector == null && deltaChildVector != null) {
        // first register a new child in the target vector
        targetDenseUnionVector.registerNewTypeId(deltaChildVector.getField());
        targetChildVector =
            targetDenseUnionVector.addVector(
                (byte) i,
                deltaChildVector.getField().createVector(targetDenseUnionVector.getAllocator()));

        // now we have both child vectors not null, we can append them.
        VectorAppender childAppender = new VectorAppender(targetChildVector);
        deltaChildVector.accept(childAppender, null);
      } else if (targetChildVector != null && deltaChildVector == null) {
        // the value only exists in the target vector, so we are done
        continue;
      } else {
        // both child vectors are non-null

        // first check vector types
        TypeEqualsVisitor childTypeVisitor =
            new TypeEqualsVisitor(
                targetChildVector, /* check name */ false, /* check meta data*/ false);
        if (!childTypeVisitor.equals(deltaChildVector)) {
          throw new IllegalArgumentException(
              "dense union vectors have different child vector types with type id " + i);
        }

        // append child vectors
        VectorAppender childAppender = new VectorAppender(targetChildVector);
        deltaChildVector.accept(childAppender, null);
      }
    }

    targetVector.setValueCount(newValueCount);
    return targetVector;
  }