[移动开发]Arrow 之 Java FieldVector

ListVector

 @Override
  public void initializeChildrenFromFields(List<Field> children) {
    if (children.size() != 1) {
      throw new IllegalArgumentException("Lists have only one child. Found: " + children);
    }
    Field field = children.get(0);
    AddOrGetResult<FieldVector> addOrGetVector = addOrGetVector(field.getFieldType());
    if (!addOrGetVector.isCreated()) {
      throw new IllegalArgumentException("Child vector already existed: " + addOrGetVector.getVector());
    }

    addOrGetVector.getVector().initializeChildrenFromFields(field.getChildren());
  }

/**
   * Get the buffers belonging to this vector.
   * @return the inner buffers.
   */
  @Override
  public List<ArrowBuf> getFieldBuffers() {
    List<ArrowBuf> result = new ArrayList<>(2);
    setReaderAndWriterIndex();
    result.add(validityBuffer);
    result.add(offsetBuffer);

    return result;
  }

MapVector

 @Override
  public void initializeChildrenFromFields(List<Field> children) {
    checkArgument(children.size() == 1, "Maps have one List child. Found: %s", children);

    Field structField = children.get(0);
    MinorType minorType = Types.getMinorTypeForArrowType(structField.getType());
    checkArgument(minorType == MinorType.STRUCT && !structField.isNullable(),
        "Map data should be a non-nullable struct type");
    checkArgument(structField.getChildren().size() == 2,
        "Map data should be a struct with 2 children. Found: %s", children);

    Field keyField = structField.getChildren().get(0);
    checkArgument(!keyField.isNullable(), "Map data key type should be a non-nullable");

    AddOrGetResult<FieldVector> addOrGetVector = addOrGetVector(structField.getFieldType());
    checkArgument(addOrGetVector.isCreated(), "Child vector already existed: %s", addOrGetVector.getVector());

    addOrGetVector.getVector().initializeChildrenFromFields(structField.getChildren());
  }