use derive_new::new;
use educe::Educe;
use replace_with::replace_with_or_abort;
use serde::{Deserialize, Serialize};
use std::{iter, marker::PhantomData, mem};
use super::{
folder_par_sink, FolderSync, FolderSyncReducer, FolderSyncReducerFactory, ParallelPipe, ParallelSink
};
#[derive(new)]
#[must_use]
pub struct Sum<I, B> {
i: I,
marker: PhantomData<fn() -> B>,
}
impl_par_dist! {
impl<I: ParallelPipe<Source>, Source, B> ParallelSink<Source>
for Sum<I, B>
where
B: iter::Sum<I::Item> + iter::Sum<B> + Send + 'static,
{
folder_par_sink!(SumFolder<B>, SumFolder<B>, self, SumFolder::new(), SumFolder::new());
}
}
#[derive(Educe, Serialize, Deserialize, new)]
#[educe(Clone)]
#[serde(bound = "")]
pub struct SumFolder<B> {
marker: PhantomData<fn() -> B>,
}
impl<A, B> FolderSync<A> for SumFolder<B>
where
B: iter::Sum<A> + iter::Sum<B>,
{
type Output = B;
fn zero(&mut self) -> Self::Output {
iter::empty::<B>().sum()
}
fn push(&mut self, state: &mut Self::Output, item: A) {
*state = iter::once(mem::replace(state, iter::empty::<B>().sum()))
.chain(iter::once(iter::once(item).sum::<B>()))
.sum();
}
}
#[derive(Clone, Serialize, Deserialize)]
pub struct SumZeroFolder<B> {
zero: Option<B>,
}
impl<B> SumZeroFolder<B> {
pub(crate) fn new(zero: B) -> Self {
Self { zero: Some(zero) }
}
}
impl<B> FolderSync<B> for SumZeroFolder<B>
where
Option<B>: iter::Sum<B>,
{
type Output = B;
fn zero(&mut self) -> Self::Output {
self.zero.take().unwrap()
}
fn push(&mut self, state: &mut Self::Output, item: B) {
replace_with_or_abort(state, |state| {
iter::once(state)
.chain(iter::once(iter::once(item).sum::<Option<B>>().unwrap()))
.sum::<Option<B>>()
.unwrap()
})
}
}