Struct UnionBuilder 

pub struct UnionBuilder { /* private fields */ }

Builder for UnionArray

Example: Dense Memory Layout

let mut builder = UnionBuilder::new_dense();
builder.append::<Int32Type>("a", 1).unwrap();
builder.append::<Float64Type>("b", 3.0).unwrap();
builder.append::<Int32Type>("a", 4).unwrap();
let union = builder.build().unwrap();

assert_eq!(union.type_id(0), 0);
assert_eq!(union.type_id(1), 1);
assert_eq!(union.type_id(2), 0);

assert_eq!(union.value_offset(0), 0);
assert_eq!(union.value_offset(1), 0);
assert_eq!(union.value_offset(2), 1);

Example: Sparse Memory Layout

let mut builder = UnionBuilder::new_sparse();
builder.append::<Int32Type>("a", 1).unwrap();
builder.append::<Float64Type>("b", 3.0).unwrap();
builder.append::<Int32Type>("a", 4).unwrap();
let union = builder.build().unwrap();

assert_eq!(union.type_id(0), 0);
assert_eq!(union.type_id(1), 1);
assert_eq!(union.type_id(2), 0);

assert_eq!(union.value_offset(0), 0);
assert_eq!(union.value_offset(1), 1);
assert_eq!(union.value_offset(2), 2);

Implementations

impl UnionBuilder

pub fn new_dense() -> UnionBuilder

Creates a new dense array builder.

pub fn new_sparse() -> UnionBuilder

Creates a new sparse array builder.

pub fn with_capacity_dense(capacity: usize) -> UnionBuilder

Creates a new dense array builder with capacity.

pub fn with_capacity_sparse(capacity: usize) -> UnionBuilder

Creates a new sparse array builder with capacity.

pub fn append_null<T>(&mut self, type_name: &str) -> Result<(), ArrowError>

where T: ArrowPrimitiveType,

Appends a null to this builder, encoding the null in the array of the type_name child / field.

Since UnionArray encodes nulls as an entry in its children (it doesn’t have a validity bitmap itself), and where the null is part of the final array, appending a NULL requires specifying which field (child) to use.

pub fn append<T>( &mut self, type_name: &str, v: <T as ArrowPrimitiveType>::Native, ) -> Result<(), ArrowError>

where T: ArrowPrimitiveType,

Appends a value to this builder.

pub fn build(self) -> Result<UnionArray, ArrowError>

Builds this builder creating a new UnionArray.

Trait Implementations

impl ArrayBuilder for UnionBuilder

fn len(&self) -> usize

Returns the number of array slots in the builder

fn finish(&mut self) -> Arc<dyn Array>

Builds the array

fn finish_cloned(&self) -> Arc<dyn Array>

Builds the array without resetting the underlying builder

fn as_any(&self) -> &(dyn Any + 'static)

Returns the builder as a non-mutable Any reference

fn as_any_mut(&mut self) -> &mut (dyn Any + 'static)

Returns the builder as a mutable Any reference

fn into_box_any(self: Box<UnionBuilder>) -> Box<dyn Any>

Returns the boxed builder as a box of Any

fn is_empty(&self) -> bool

Returns whether number of array slots is zero

impl Debug for UnionBuilder

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

Formats the value using the given formatter.

impl Default for UnionBuilder

fn default() -> UnionBuilder

Returns the “default value” for a type.