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use super::plumbing::*;
use super::*;
use std::sync::atomic::{AtomicBool, Ordering};
/// `WhileSome` is an iterator that yields the `Some` elements of an iterator,
/// halting as soon as any `None` is produced.
///
/// This struct is created by the [`while_some()`] method on [`ParallelIterator`]
///
/// [`while_some()`]: trait.ParallelIterator.html#method.while_some
/// [`ParallelIterator`]: trait.ParallelIterator.html
#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
#[derive(Debug, Clone)]
pub struct WhileSome<I: ParallelIterator> {
base: I,
}
impl<I> WhileSome<I>
where
I: ParallelIterator,
{
/// Creates a new `WhileSome` iterator.
pub(super) fn new(base: I) -> Self {
WhileSome { base }
}
}
impl<I, T> ParallelIterator for WhileSome<I>
where
I: ParallelIterator<Item = Option<T>>,
T: Send,
{
type Item = T;
fn drive_unindexed<C>(self, consumer: C) -> C::Result
where
C: UnindexedConsumer<Self::Item>,
{
let full = AtomicBool::new(false);
let consumer1 = WhileSomeConsumer {
base: consumer,
full: &full,
};
self.base.drive_unindexed(consumer1)
}
}
/// ////////////////////////////////////////////////////////////////////////
/// Consumer implementation
struct WhileSomeConsumer<'f, C> {
base: C,
full: &'f AtomicBool,
}
impl<'f, T, C> Consumer<Option<T>> for WhileSomeConsumer<'f, C>
where
C: Consumer<T>,
T: Send,
{
type Folder = WhileSomeFolder<'f, C::Folder>;
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);
(
WhileSomeConsumer { base: left, ..self },
WhileSomeConsumer {
base: right,
..self
},
reducer,
)
}
fn into_folder(self) -> Self::Folder {
WhileSomeFolder {
base: self.base.into_folder(),
full: self.full,
}
}
fn full(&self) -> bool {
self.full.load(Ordering::Relaxed) || self.base.full()
}
}
impl<'f, T, C> UnindexedConsumer<Option<T>> for WhileSomeConsumer<'f, C>
where
C: UnindexedConsumer<T>,
T: Send,
{
fn split_off_left(&self) -> Self {
WhileSomeConsumer {
base: self.base.split_off_left(),
..*self
}
}
fn to_reducer(&self) -> Self::Reducer {
self.base.to_reducer()
}
}
struct WhileSomeFolder<'f, C> {
base: C,
full: &'f AtomicBool,
}
impl<'f, T, C> Folder<Option<T>> for WhileSomeFolder<'f, C>
where
C: Folder<T>,
{
type Result = C::Result;
fn consume(mut self, item: Option<T>) -> Self {
match item {
Some(item) => self.base = self.base.consume(item),
None => self.full.store(true, Ordering::Relaxed),
}
self
}
fn consume_iter<I>(mut self, iter: I) -> Self
where
I: IntoIterator<Item = Option<T>>,
{
fn some<T>(full: &AtomicBool) -> impl Fn(&Option<T>) -> bool + '_ {
move |x| match *x {
Some(_) => !full.load(Ordering::Relaxed),
None => {
full.store(true, Ordering::Relaxed);
false
}
}
}
self.base = self.base.consume_iter(
iter.into_iter()
.take_while(some(self.full))
.map(Option::unwrap),
);
self
}
fn complete(self) -> C::Result {
self.base.complete()
}
fn full(&self) -> bool {
self.full.load(Ordering::Relaxed) || self.base.full()
}
}