Struct arrow_array::builder::MapBuilder

pub struct MapBuilder<K: ArrayBuilder, V: ArrayBuilder> { /* private fields */ }

Builder for MapArray

let string_builder = StringBuilder::new();
let int_builder = Int32Builder::with_capacity(4);

// Construct `[{"joe": 1}, {"blogs": 2, "foo": 4}, {}, null]`
let mut builder = MapBuilder::new(None, string_builder, int_builder);

builder.keys().append_value("joe");
builder.values().append_value(1);
builder.append(true).unwrap();

builder.keys().append_value("blogs");
builder.values().append_value(2);
builder.keys().append_value("foo");
builder.values().append_value(4);
builder.append(true).unwrap();
builder.append(true).unwrap();
builder.append(false).unwrap();

let array = builder.finish();
assert_eq!(array.value_offsets(), &[0, 1, 3, 3, 3]);
assert_eq!(array.values().as_ref(), &Int32Array::from(vec![1, 2, 4]));
assert_eq!(array.keys().as_ref(), &StringArray::from(vec!["joe", "blogs", "foo"]));

Implementations

impl<K: ArrayBuilder, V: ArrayBuilder> MapBuilder<K, V>

pub fn new( field_names: Option<MapFieldNames>, key_builder: K, value_builder: V, ) -> Self

Creates a new MapBuilder

pub fn with_capacity( field_names: Option<MapFieldNames>, key_builder: K, value_builder: V, capacity: usize, ) -> Self

Creates a new MapBuilder with capacity

pub fn with_values_field(self, field: impl Into<FieldRef>) -> Self

Override the field passed to MapBuilder::new

By default a nullable field is created with the name values

Note: Self::finish and Self::finish_cloned will panic if the field’s data type does not match that of V

pub fn keys(&mut self) -> &mut K

Returns the key array builder of the map

pub fn values(&mut self) -> &mut V

Returns the value array builder of the map

pub fn entries(&mut self) -> (&mut K, &mut V)

Returns both the key and value array builders of the map

pub fn append(&mut self, is_valid: bool) -> Result<(), ArrowError>

Finish the current map array slot

Returns an error if the key and values builders are in an inconsistent state.

pub fn finish(&mut self) -> MapArray

Builds the MapArray

pub fn finish_cloned(&self) -> MapArray

Builds the MapArray without resetting the builder.

pub fn validity_slice(&self) -> Option<&[u8]>

Returns the current null buffer as a slice

Trait Implementations

impl<K: ArrayBuilder, V: ArrayBuilder> ArrayBuilder for MapBuilder<K, V>

fn finish_cloned(&self) -> ArrayRef

Builds the array without resetting the builder.

fn len(&self) -> usize

Returns the number of array slots in the builder

fn finish(&mut self) -> ArrayRef

Builds the array

fn as_any(&self) -> &dyn Any

Returns the builder as a non-mutable Any reference.

fn as_any_mut(&mut self) -> &mut dyn Any

Returns the builder as a mutable Any reference.

fn into_box_any(self: Box<Self>) -> 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<K: Debug + ArrayBuilder, V: Debug + ArrayBuilder> Debug for MapBuilder<K, V>

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

Formats the value using the given formatter.