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use crate::{
bitmap::Bitmap,
datatypes::{DataType, Field},
error::Error,
offset::{Offset, Offsets, OffsetsBuffer},
};
use super::{new_empty_array, specification::try_check_offsets_bounds, Array};
#[cfg(feature = "arrow")]
mod data;
mod ffi;
pub(super) mod fmt;
mod iterator;
pub use iterator::*;
mod mutable;
pub use mutable::*;
/// An [`Array`] semantically equivalent to `Vec<Option<Vec<Option<T>>>>` with Arrow's in-memory.
#[derive(Clone)]
pub struct ListArray<O: Offset> {
data_type: DataType,
offsets: OffsetsBuffer<O>,
values: Box<dyn Array>,
validity: Option<Bitmap>,
}
impl<O: Offset> ListArray<O> {
/// Creates a new [`ListArray`].
///
/// # Errors
/// This function returns an error iff:
/// * The last offset is not equal to the values' length.
/// * the validity's length is not equal to `offsets.len()`.
/// * The `data_type`'s [`crate::datatypes::PhysicalType`] is not equal to either [`crate::datatypes::PhysicalType::List`] or [`crate::datatypes::PhysicalType::LargeList`].
/// * The `data_type`'s inner field's data type is not equal to `values.data_type`.
/// # Implementation
/// This function is `O(1)`
pub fn try_new(
data_type: DataType,
offsets: OffsetsBuffer<O>,
values: Box<dyn Array>,
validity: Option<Bitmap>,
) -> Result<Self, Error> {
try_check_offsets_bounds(&offsets, values.len())?;
if validity
.as_ref()
.map_or(false, |validity| validity.len() != offsets.len_proxy())
{
return Err(Error::oos(
"validity mask length must match the number of values",
));
}
let child_data_type = Self::try_get_child(&data_type)?.data_type();
let values_data_type = values.data_type();
if child_data_type != values_data_type {
return Err(Error::oos(
format!("ListArray's child's DataType must match. However, the expected DataType is {child_data_type:?} while it got {values_data_type:?}."),
));
}
Ok(Self {
data_type,
offsets,
values,
validity,
})
}
/// Creates a new [`ListArray`].
///
/// # Panics
/// This function panics iff:
/// * The last offset is not equal to the values' length.
/// * the validity's length is not equal to `offsets.len()`.
/// * The `data_type`'s [`crate::datatypes::PhysicalType`] is not equal to either [`crate::datatypes::PhysicalType::List`] or [`crate::datatypes::PhysicalType::LargeList`].
/// * The `data_type`'s inner field's data type is not equal to `values.data_type`.
/// # Implementation
/// This function is `O(1)`
pub fn new(
data_type: DataType,
offsets: OffsetsBuffer<O>,
values: Box<dyn Array>,
validity: Option<Bitmap>,
) -> Self {
Self::try_new(data_type, offsets, values, validity).unwrap()
}
/// Returns a new empty [`ListArray`].
pub fn new_empty(data_type: DataType) -> Self {
let values = new_empty_array(Self::get_child_type(&data_type).clone());
Self::new(data_type, OffsetsBuffer::default(), values, None)
}
/// Returns a new null [`ListArray`].
#[inline]
pub fn new_null(data_type: DataType, length: usize) -> Self {
let child = Self::get_child_type(&data_type).clone();
Self::new(
data_type,
Offsets::new_zeroed(length).into(),
new_empty_array(child),
Some(Bitmap::new_zeroed(length)),
)
}
}
impl<O: Offset> ListArray<O> {
/// Slices this [`ListArray`].
/// # Panics
/// panics iff `offset + length >= self.len()`
pub fn slice(&mut self, offset: usize, length: usize) {
assert!(
offset + length <= self.len(),
"the offset of the new Buffer cannot exceed the existing length"
);
unsafe { self.slice_unchecked(offset, length) }
}
/// Slices this [`ListArray`].
/// # Safety
/// The caller must ensure that `offset + length < self.len()`.
pub unsafe fn slice_unchecked(&mut self, offset: usize, length: usize) {
self.validity.as_mut().and_then(|bitmap| {
bitmap.slice_unchecked(offset, length);
(bitmap.unset_bits() > 0).then(|| bitmap)
});
self.offsets.slice_unchecked(offset, length + 1);
}
impl_sliced!();
impl_mut_validity!();
impl_into_array!();
}
// Accessors
impl<O: Offset> ListArray<O> {
/// Returns the length of this array
#[inline]
pub fn len(&self) -> usize {
self.offsets.len_proxy()
}
/// Returns the element at index `i`
/// # Panic
/// Panics iff `i >= self.len()`
#[inline]
pub fn value(&self, i: usize) -> Box<dyn Array> {
assert!(i < self.len());
// Safety: invariant of this function
unsafe { self.value_unchecked(i) }
}
/// Returns the element at index `i` as &str
/// # Safety
/// Assumes that the `i < self.len`.
#[inline]
pub unsafe fn value_unchecked(&self, i: usize) -> Box<dyn Array> {
// safety: the invariant of the function
let (start, end) = self.offsets.start_end_unchecked(i);
let length = end - start;
// safety: the invariant of the struct
self.values.sliced_unchecked(start, length)
}
/// The optional validity.
#[inline]
pub fn validity(&self) -> Option<&Bitmap> {
self.validity.as_ref()
}
/// The offsets [`Buffer`].
#[inline]
pub fn offsets(&self) -> &OffsetsBuffer<O> {
&self.offsets
}
/// The values.
#[inline]
pub fn values(&self) -> &Box<dyn Array> {
&self.values
}
}
impl<O: Offset> ListArray<O> {
/// Returns a default [`DataType`]: inner field is named "item" and is nullable
pub fn default_datatype(data_type: DataType) -> DataType {
let field = Box::new(Field::new("item", data_type, true));
if O::IS_LARGE {
DataType::LargeList(field)
} else {
DataType::List(field)
}
}
/// Returns a the inner [`Field`]
/// # Panics
/// Panics iff the logical type is not consistent with this struct.
pub fn get_child_field(data_type: &DataType) -> &Field {
Self::try_get_child(data_type).unwrap()
}
/// Returns a the inner [`Field`]
/// # Errors
/// Panics iff the logical type is not consistent with this struct.
pub fn try_get_child(data_type: &DataType) -> Result<&Field, Error> {
if O::IS_LARGE {
match data_type.to_logical_type() {
DataType::LargeList(child) => Ok(child.as_ref()),
_ => Err(Error::oos("ListArray<i64> expects DataType::LargeList")),
}
} else {
match data_type.to_logical_type() {
DataType::List(child) => Ok(child.as_ref()),
_ => Err(Error::oos("ListArray<i32> expects DataType::List")),
}
}
}
/// Returns a the inner [`DataType`]
/// # Panics
/// Panics iff the logical type is not consistent with this struct.
pub fn get_child_type(data_type: &DataType) -> &DataType {
Self::get_child_field(data_type).data_type()
}
}
impl<O: Offset> Array for ListArray<O> {
impl_common_array!();
fn validity(&self) -> Option<&Bitmap> {
self.validity.as_ref()
}
#[inline]
fn with_validity(&self, validity: Option<Bitmap>) -> Box<dyn Array> {
Box::new(self.clone().with_validity(validity))
}
}