Struct VariantArrayBuilder

pub struct VariantArrayBuilder {
    nulls: NullBufferBuilder,
    metadata_buffer: Vec<u8>,
    metadata_locations: Vec<(usize, usize)>,
    value_buffer: Vec<u8>,
    value_locations: Vec<(usize, usize)>,
    fields: Fields,
}

A builder for VariantArray

This builder is used to construct a VariantArray and allows APIs for adding metadata

This builder always creates a VariantArray using [BinaryViewArray] for both the metadata and value fields.

TODO

1. Support shredding: https://github.com/apache/arrow-rs/issues/7895

Example:

// Create a new VariantArrayBuilder with a capacity of 100 rows
let mut builder = VariantArrayBuilder::new(100);
// append variant values
builder.append_variant(Variant::from(42));
// append a null row
builder.append_null();
// append a pre-constructed metadata and value buffers
let (metadata, value) = {
  let mut vb = VariantBuilder::new();
  let mut obj = vb.new_object();
  obj.insert("foo", "bar");
  obj.finish().unwrap();
  vb.finish()
};
builder.append_variant_buffers(&metadata, &value);

// create the final VariantArray
let variant_array = builder.build();
assert_eq!(variant_array.len(), 3);
// // Access the values
// row 1 is not null and is an integer
assert!(!variant_array.is_null(0));
assert_eq!(variant_array.value(0), Variant::from(42i32));
// row 1 is null
assert!(variant_array.is_null(1));
// row 2 is not null and is an object
assert!(!variant_array.is_null(2));
assert!(variant_array.value(2).as_object().is_some());

Fields

nulls: NullBufferBuilder

Nulls

metadata_buffer: Vec<u8>

buffer for all the metadata

metadata_locations: Vec<(usize, usize)>

(offset, len) pairs for locations of metadata in the buffer

value_buffer: Vec<u8>

buffer for values

value_locations: Vec<(usize, usize)>

(offset, len) pairs for locations of values in the buffer

fields: Fields

The fields of the final StructArray

TODO: 1) Add extension type metadata TODO: 2) Add support for shredding

Implementations

impl VariantArrayBuilder

pub fn new(row_capacity: usize) -> Self

pub fn build(self) -> VariantArray

Build the final builder

pub fn append_null(&mut self)

Appends a null row to the builder.

pub fn append_variant(&mut self, variant: Variant<'_, '_>)

Append the [Variant] to the builder as the next row

pub fn append_variant_buffers(&mut self, metadata: &[u8], value: &[u8])

Append a metadata and values buffer to the builder

Trait Implementations

impl Debug for VariantArrayBuilder

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.