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use crate::observer::{error_proxy_impl, is_stopped_proxy_impl};
use crate::prelude::*;
use observable::observable_proxy_impl;
use std::collections::VecDeque;
#[derive(Clone)]
pub struct TakeLastOp<S> {
pub(crate) source: S,
pub(crate) count: usize,
}
#[doc(hidden)]
macro observable_impl($subscription:ty, $($marker:ident +)* $lf: lifetime) {
fn actual_subscribe<O: Observer<Self::Item, Self::Err> + $($marker +)* $lf>(
self,
subscriber: Subscriber<O, $subscription>,
) -> Self::Unsub {
let subscriber = Subscriber {
observer: TakeLastObserver {
observer: subscriber.observer,
count: self.count,
queue: VecDeque::new(),
},
subscription: subscriber.subscription,
};
self.source.actual_subscribe(subscriber)
}
}
observable_proxy_impl!(TakeLastOp, S);
impl<'a, S> LocalObservable<'a> for TakeLastOp<S>
where
S: LocalObservable<'a> + 'a,
{
type Unsub = S::Unsub;
observable_impl!(LocalSubscription, 'a);
}
impl<S> SharedObservable for TakeLastOp<S>
where
S: SharedObservable,
S::Item: Send + Sync + 'static,
{
type Unsub = S::Unsub;
observable_impl!(SharedSubscription, Send + Sync + 'static);
}
pub struct TakeLastObserver<O, Item> {
observer: O,
count: usize,
queue: VecDeque<Item>,
}
impl<Item, Err, O> Observer<Item, Err> for TakeLastObserver<O, Item>
where
O: Observer<Item, Err>,
{
fn next(&mut self, value: Item) {
self.queue.push_back(value);
while self.queue.len() > self.count {
self.queue.pop_front();
}
}
error_proxy_impl!(Err, observer);
fn complete(&mut self) {
for value in self.queue.drain(..) {
self.observer.next(value);
}
self.observer.complete();
}
is_stopped_proxy_impl!(observer);
}
#[cfg(test)]
mod test {
use crate::prelude::*;
#[test]
fn base_function() {
let mut completed = false;
let mut ticks = vec![];
observable::from_iter(0..100)
.take_last(5)
.subscribe_complete(|v| ticks.push(v), || completed = true);
assert_eq!(ticks, vec![95, 96, 97, 98, 99]);
assert_eq!(completed, true);
}
#[test]
fn take_last_support_fork() {
let mut nc1 = 0;
let mut nc2 = 0;
{
let take_last5 = observable::from_iter(0..100).take_last(5);
let f1 = take_last5.clone();
let f2 = take_last5;
f1.take_last(5).subscribe(|_| nc1 += 1);
f2.take_last(5).subscribe(|_| nc2 += 1);
}
assert_eq!(nc1, 5);
assert_eq!(nc2, 5);
}
#[test]
fn into_shared() {
observable::from_iter(0..100)
.take_last(5)
.take_last(5)
.to_shared()
.subscribe(|_| {});
}
}