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use super::plumbing::*;
use super::ParallelIterator;
pub(super) fn reduce<PI, R, ID, T>(pi: PI, identity: ID, reduce_op: R) -> T
where
PI: ParallelIterator<Item = T>,
R: Fn(T, T) -> T + Sync,
ID: Fn() -> T + Sync,
T: Send,
{
let consumer = ReduceConsumer {
identity: &identity,
reduce_op: &reduce_op,
};
pi.drive_unindexed(consumer)
}
struct ReduceConsumer<'r, R, ID> {
identity: &'r ID,
reduce_op: &'r R,
}
impl<'r, R, ID> Copy for ReduceConsumer<'r, R, ID> {}
impl<'r, R, ID> Clone for ReduceConsumer<'r, R, ID> {
fn clone(&self) -> Self {
*self
}
}
impl<'r, R, ID, T> Consumer<T> for ReduceConsumer<'r, R, ID>
where
R: Fn(T, T) -> T + Sync,
ID: Fn() -> T + Sync,
T: Send,
{
type Folder = ReduceFolder<'r, R, T>;
type Reducer = Self;
type Result = T;
fn split_at(self, _index: usize) -> (Self, Self, Self) {
(self, self, self)
}
fn into_folder(self) -> Self::Folder {
ReduceFolder {
reduce_op: self.reduce_op,
item: (self.identity)(),
}
}
fn full(&self) -> bool {
false
}
}
impl<'r, R, ID, T> UnindexedConsumer<T> for ReduceConsumer<'r, R, ID>
where
R: Fn(T, T) -> T + Sync,
ID: Fn() -> T + Sync,
T: Send,
{
fn split_off_left(&self) -> Self {
*self
}
fn to_reducer(&self) -> Self::Reducer {
*self
}
}
impl<'r, R, ID, T> Reducer<T> for ReduceConsumer<'r, R, ID>
where
R: Fn(T, T) -> T + Sync,
{
fn reduce(self, left: T, right: T) -> T {
(self.reduce_op)(left, right)
}
}
struct ReduceFolder<'r, R, T> {
reduce_op: &'r R,
item: T,
}
impl<'r, R, T> Folder<T> for ReduceFolder<'r, R, T>
where
R: Fn(T, T) -> T,
{
type Result = T;
fn consume(self, item: T) -> Self {
ReduceFolder {
reduce_op: self.reduce_op,
item: (self.reduce_op)(self.item, item),
}
}
fn consume_iter<I>(self, iter: I) -> Self
where
I: IntoIterator<Item = T>,
{
ReduceFolder {
reduce_op: self.reduce_op,
item: iter.into_iter().fold(self.item, self.reduce_op),
}
}
fn complete(self) -> T {
self.item
}
fn full(&self) -> bool {
false
}
}