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use super::super::{ffi::ToFfi, Array, FromFfi};
use super::StructArray;
use crate::{error::Result, ffi};
unsafe impl ToFfi for StructArray {
fn buffers(&self) -> Vec<Option<*const u8>> {
vec![self.validity.as_ref().map(|x| x.as_ptr())]
}
fn children(&self) -> Vec<Box<dyn Array>> {
self.values.clone()
}
fn offset(&self) -> Option<usize> {
Some(
self.validity
.as_ref()
.map(|bitmap| bitmap.offset())
.unwrap_or_default(),
)
}
fn to_ffi_aligned(&self) -> Self {
self.clone()
}
}
impl<A: ffi::ArrowArrayRef> FromFfi<A> for StructArray {
unsafe fn try_from_ffi(array: A) -> Result<Self> {
let data_type = array.data_type().clone();
let fields = Self::get_fields(&data_type);
let arrow_array = array.array();
let validity = unsafe { array.validity() }?;
let len = arrow_array.len();
let offset = arrow_array.offset();
let values = (0..fields.len())
.map(|index| {
let child = array.child(index)?;
ffi::try_from(child).map(|arr| {
// there is a discrepancy with how arrow2 exports sliced
// struct array and how pyarrow does it.
// # Pyarrow
// ## struct array len 3
// * slice 1 by with len 2
// offset on struct array: 1
// length on struct array: 2
// offset on value array: 0
// length on value array: 3
// # Arrow2
// ## struct array len 3
// * slice 1 by with len 2
// offset on struct array: 0
// length on struct array: 3
// offset on value array: 1
// length on value array: 2
//
// this branch will ensure both can round trip
if arr.len() >= (len + offset) {
arr.sliced(offset, len)
} else {
arr
}
})
})
.collect::<Result<Vec<Box<dyn Array>>>>()?;
Self::try_new(data_type, values, validity)
}
}