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use std::borrow::Cow;
use std::error::Error;
use bytemuck::{Pod, PodCastError, try_cast_slice, pod_collect_to_vec};
use heed_traits::{BytesDecode, BytesEncode};
pub struct CowSlice<T>(std::marker::PhantomData<T>);
impl<'a, T: Pod> BytesEncode<'a> for CowSlice<T> {
type EItem = [T];
fn bytes_encode(item: &'a Self::EItem) -> Result<Cow<'a, [u8]>, Box<dyn Error>> {
try_cast_slice(item).map(Cow::Borrowed).map_err(Into::into)
}
}
impl<'a, T: Pod> BytesDecode<'a> for CowSlice<T> {
type DItem = Cow<'a, [T]>;
fn bytes_decode(bytes: &'a [u8]) -> Result<Self::DItem, Box<dyn Error>> {
match try_cast_slice(bytes) {
Ok(items) => Ok(Cow::Borrowed(items)),
Err(PodCastError::AlignmentMismatch) => Ok(Cow::Owned(pod_collect_to_vec(bytes))),
Err(e) => Err(e.into()),
}
}
}
unsafe impl<T> Send for CowSlice<T> {}
unsafe impl<T> Sync for CowSlice<T> {}