Struct MapBuilder 

pub struct MapBuilder<K: ArrayBuilder, V: ArrayBuilder> {
    offsets_builder: Vec<i32>,
    null_buffer_builder: NullBufferBuilder,
    field_names: MapFieldNames,
    key_builder: K,
    value_builder: V,
    key_field: Option<FieldRef>,
    value_field: Option<FieldRef>,
}

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"]));

Fields

offsets_builder: Vec<i32>

null_buffer_builder: NullBufferBuilder

field_names: MapFieldNames

key_builder: K

value_builder: V

key_field: Option<FieldRef>

value_field: Option<FieldRef>

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_keys_field(self, field: impl Into<FieldRef>) -> Self

Override the field passed to MapBuilder::new

By default, a non-nullable field is created with the name keys

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

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

fn validate_equal_lengths(&self) -> Result<(), ArrowError>

Validates that key and value builders have equal lengths.

fn next_offset(&self) -> Result<i32, ArrowError>

Returns the offset of the next map slot, i.e. the current number of entries.

Returns an error if the number of entries does not fit in an i32 offset.

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, or if the number of entries exceeds i32::MAX.

pub fn append_nulls(&mut self, n: usize) -> Result<(), ArrowError>

Append n nulls to this MapBuilder

Returns an error if the key and values builders are in an inconsistent state, or if the number of entries exceeds i32::MAX.

pub fn finish(&mut self) -> MapArray

Builds the MapArray

Panics

Panics if the fields set with Self::with_keys_field or Self::with_values_field do not match the data types of the key and value builders, or if the keys contain nulls

pub fn finish_cloned(&self) -> MapArray

Builds the MapArray without resetting the builder.

Panics

Panics if the fields set with Self::with_keys_field or Self::with_values_field do not match the data types of the key and value builders, or if the keys contain nulls

fn finish_preserve_values(&mut self) -> MapArray

fn finish_helper( &self, keys_arr: Arc<dyn Array>, values_arr: Arc<dyn Array>, offset_buffer: Buffer, nulls: Option<NullBuffer>, len: usize, ) -> MapArray

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 finish_preserve_values(&mut self) -> ArrayRef

Builds the array without resetting the values builder.

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.