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use super::plumbing::*;
use super::*;
use std::fmt;
use std::sync::atomic::{AtomicBool, Ordering};
/// `TakeAnyWhile` is an iterator that iterates over elements from anywhere in `I`
/// until the callback returns `false`.
/// This struct is created by the [`take_any_while()`] method on [`ParallelIterator`]
///
/// [`take_any_while()`]: trait.ParallelIterator.html#method.take_any_while
/// [`ParallelIterator`]: trait.ParallelIterator.html
#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
#[derive(Clone)]
pub struct TakeAnyWhile<I: ParallelIterator, P> {
base: I,
predicate: P,
}
impl<I: ParallelIterator + fmt::Debug, P> fmt::Debug for TakeAnyWhile<I, P> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("TakeAnyWhile")
.field("base", &self.base)
.finish()
}
}
impl<I, P> TakeAnyWhile<I, P>
where
I: ParallelIterator,
{
/// Creates a new `TakeAnyWhile` iterator.
pub(super) fn new(base: I, predicate: P) -> Self {
TakeAnyWhile { base, predicate }
}
}
impl<I, P> ParallelIterator for TakeAnyWhile<I, P>
where
I: ParallelIterator,
P: Fn(&I::Item) -> bool + Sync + Send,
{
type Item = I::Item;
fn drive_unindexed<C>(self, consumer: C) -> C::Result
where
C: UnindexedConsumer<Self::Item>,
{
let consumer1 = TakeAnyWhileConsumer {
base: consumer,
predicate: &self.predicate,
taking: &AtomicBool::new(true),
};
self.base.drive_unindexed(consumer1)
}
}
/// ////////////////////////////////////////////////////////////////////////
/// Consumer implementation
struct TakeAnyWhileConsumer<'p, C, P> {
base: C,
predicate: &'p P,
taking: &'p AtomicBool,
}
impl<'p, T, C, P> Consumer<T> for TakeAnyWhileConsumer<'p, C, P>
where
C: Consumer<T>,
P: Fn(&T) -> bool + Sync,
{
type Folder = TakeAnyWhileFolder<'p, C::Folder, P>;
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);
(
TakeAnyWhileConsumer { base: left, ..self },
TakeAnyWhileConsumer {
base: right,
..self
},
reducer,
)
}
fn into_folder(self) -> Self::Folder {
TakeAnyWhileFolder {
base: self.base.into_folder(),
predicate: self.predicate,
taking: self.taking,
}
}
fn full(&self) -> bool {
!self.taking.load(Ordering::Relaxed) || self.base.full()
}
}
impl<'p, T, C, P> UnindexedConsumer<T> for TakeAnyWhileConsumer<'p, C, P>
where
C: UnindexedConsumer<T>,
P: Fn(&T) -> bool + Sync,
{
fn split_off_left(&self) -> Self {
TakeAnyWhileConsumer {
base: self.base.split_off_left(),
..*self
}
}
fn to_reducer(&self) -> Self::Reducer {
self.base.to_reducer()
}
}
struct TakeAnyWhileFolder<'p, C, P> {
base: C,
predicate: &'p P,
taking: &'p AtomicBool,
}
fn take<T>(item: &T, taking: &AtomicBool, predicate: &impl Fn(&T) -> bool) -> bool {
if !taking.load(Ordering::Relaxed) {
return false;
}
if predicate(item) {
return true;
}
taking.store(false, Ordering::Relaxed);
false
}
impl<'p, T, C, P> Folder<T> for TakeAnyWhileFolder<'p, C, P>
where
C: Folder<T>,
P: Fn(&T) -> bool + 'p,
{
type Result = C::Result;
fn consume(mut self, item: T) -> Self {
if take(&item, self.taking, self.predicate) {
self.base = self.base.consume(item);
}
self
}
fn consume_iter<I>(mut self, iter: I) -> Self
where
I: IntoIterator<Item = T>,
{
self.base = self.base.consume_iter(
iter.into_iter()
.take_while(move |x| take(x, self.taking, self.predicate)),
);
self
}
fn complete(self) -> C::Result {
self.base.complete()
}
fn full(&self) -> bool {
!self.taking.load(Ordering::Relaxed) || self.base.full()
}
}