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use super::plumbing::*;
use super::*;
use std::fmt::{self, Debug};
/// `Update` is an iterator that mutates the elements of an
/// underlying iterator before they are yielded.
///
/// This struct is created by the [`update()`] method on [`ParallelIterator`]
///
/// [`update()`]: trait.ParallelIterator.html#method.update
/// [`ParallelIterator`]: trait.ParallelIterator.html
#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
#[derive(Clone)]
pub struct Update<I: ParallelIterator, F> {
base: I,
update_op: F,
}
impl<I: ParallelIterator + Debug, F> Debug for Update<I, F> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("Update").field("base", &self.base).finish()
}
}
impl<I, F> Update<I, F>
where
I: ParallelIterator,
{
/// Creates a new `Update` iterator.
pub(super) fn new(base: I, update_op: F) -> Self {
Update { base, update_op }
}
}
impl<I, F> ParallelIterator for Update<I, F>
where
I: ParallelIterator,
F: Fn(&mut I::Item) + Send + Sync,
{
type Item = I::Item;
fn drive_unindexed<C>(self, consumer: C) -> C::Result
where
C: UnindexedConsumer<Self::Item>,
{
let consumer1 = UpdateConsumer::new(consumer, &self.update_op);
self.base.drive_unindexed(consumer1)
}
fn opt_len(&self) -> Option<usize> {
self.base.opt_len()
}
}
impl<I, F> IndexedParallelIterator for Update<I, F>
where
I: IndexedParallelIterator,
F: Fn(&mut I::Item) + Send + Sync,
{
fn drive<C>(self, consumer: C) -> C::Result
where
C: Consumer<Self::Item>,
{
let consumer1 = UpdateConsumer::new(consumer, &self.update_op);
self.base.drive(consumer1)
}
fn len(&self) -> usize {
self.base.len()
}
fn with_producer<CB>(self, callback: CB) -> CB::Output
where
CB: ProducerCallback<Self::Item>,
{
return self.base.with_producer(Callback {
callback,
update_op: self.update_op,
});
struct Callback<CB, F> {
callback: CB,
update_op: F,
}
impl<T, F, CB> ProducerCallback<T> for Callback<CB, F>
where
CB: ProducerCallback<T>,
F: Fn(&mut T) + Send + Sync,
{
type Output = CB::Output;
fn callback<P>(self, base: P) -> CB::Output
where
P: Producer<Item = T>,
{
let producer = UpdateProducer {
base,
update_op: &self.update_op,
};
self.callback.callback(producer)
}
}
}
}
/// ////////////////////////////////////////////////////////////////////////
struct UpdateProducer<'f, P, F> {
base: P,
update_op: &'f F,
}
impl<'f, P, F> Producer for UpdateProducer<'f, P, F>
where
P: Producer,
F: Fn(&mut P::Item) + Send + Sync,
{
type Item = P::Item;
type IntoIter = UpdateSeq<P::IntoIter, &'f F>;
fn into_iter(self) -> Self::IntoIter {
UpdateSeq {
base: self.base.into_iter(),
update_op: self.update_op,
}
}
fn min_len(&self) -> usize {
self.base.min_len()
}
fn max_len(&self) -> usize {
self.base.max_len()
}
fn split_at(self, index: usize) -> (Self, Self) {
let (left, right) = self.base.split_at(index);
(
UpdateProducer {
base: left,
update_op: self.update_op,
},
UpdateProducer {
base: right,
update_op: self.update_op,
},
)
}
fn fold_with<G>(self, folder: G) -> G
where
G: Folder<Self::Item>,
{
let folder1 = UpdateFolder {
base: folder,
update_op: self.update_op,
};
self.base.fold_with(folder1).base
}
}
/// ////////////////////////////////////////////////////////////////////////
/// Consumer implementation
struct UpdateConsumer<'f, C, F> {
base: C,
update_op: &'f F,
}
impl<'f, C, F> UpdateConsumer<'f, C, F> {
fn new(base: C, update_op: &'f F) -> Self {
UpdateConsumer { base, update_op }
}
}
impl<'f, T, C, F> Consumer<T> for UpdateConsumer<'f, C, F>
where
C: Consumer<T>,
F: Fn(&mut T) + Send + Sync,
{
type Folder = UpdateFolder<'f, C::Folder, F>;
type Reducer = C::Reducer;
type Result = C::Result;
fn split_at(self, index: usize) -> (Self, Self, Self::Reducer) {
let (left, right, reducer) = self.base.split_at(index);
(
UpdateConsumer::new(left, self.update_op),
UpdateConsumer::new(right, self.update_op),
reducer,
)
}
fn into_folder(self) -> Self::Folder {
UpdateFolder {
base: self.base.into_folder(),
update_op: self.update_op,
}
}
fn full(&self) -> bool {
self.base.full()
}
}
impl<'f, T, C, F> UnindexedConsumer<T> for UpdateConsumer<'f, C, F>
where
C: UnindexedConsumer<T>,
F: Fn(&mut T) + Send + Sync,
{
fn split_off_left(&self) -> Self {
UpdateConsumer::new(self.base.split_off_left(), self.update_op)
}
fn to_reducer(&self) -> Self::Reducer {
self.base.to_reducer()
}
}
struct UpdateFolder<'f, C, F> {
base: C,
update_op: &'f F,
}
fn apply<T>(update_op: impl Fn(&mut T)) -> impl Fn(T) -> T {
move |mut item| {
update_op(&mut item);
item
}
}
impl<'f, T, C, F> Folder<T> for UpdateFolder<'f, C, F>
where
C: Folder<T>,
F: Fn(&mut T),
{
type Result = C::Result;
fn consume(self, mut item: T) -> Self {
(self.update_op)(&mut item);
UpdateFolder {
base: self.base.consume(item),
update_op: self.update_op,
}
}
fn consume_iter<I>(mut self, iter: I) -> Self
where
I: IntoIterator<Item = T>,
{
let update_op = self.update_op;
self.base = self
.base
.consume_iter(iter.into_iter().map(apply(update_op)));
self
}
fn complete(self) -> C::Result {
self.base.complete()
}
fn full(&self) -> bool {
self.base.full()
}
}
/// Standard Update adaptor, based on `itertools::adaptors::Update`
#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
#[derive(Debug, Clone)]
struct UpdateSeq<I, F> {
base: I,
update_op: F,
}
impl<I, F> Iterator for UpdateSeq<I, F>
where
I: Iterator,
F: Fn(&mut I::Item),
{
type Item = I::Item;
fn next(&mut self) -> Option<Self::Item> {
let mut v = self.base.next()?;
(self.update_op)(&mut v);
Some(v)
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.base.size_hint()
}
fn fold<Acc, G>(self, init: Acc, g: G) -> Acc
where
G: FnMut(Acc, Self::Item) -> Acc,
{
self.base.map(apply(self.update_op)).fold(init, g)
}
// if possible, re-use inner iterator specializations in collect
fn collect<C>(self) -> C
where
C: ::std::iter::FromIterator<Self::Item>,
{
self.base.map(apply(self.update_op)).collect()
}
}
impl<I, F> ExactSizeIterator for UpdateSeq<I, F>
where
I: ExactSizeIterator,
F: Fn(&mut I::Item),
{
}
impl<I, F> DoubleEndedIterator for UpdateSeq<I, F>
where
I: DoubleEndedIterator,
F: Fn(&mut I::Item),
{
fn next_back(&mut self) -> Option<Self::Item> {
let mut v = self.base.next_back()?;
(self.update_op)(&mut v);
Some(v)
}
}