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use crate::prelude::*; use observable::observable_proxy_impl; use observer::{error_proxy_impl, is_stopped_proxy_impl}; use std::collections::VecDeque; #[derive(Clone)] pub struct SkipLastOp<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: SkipLastObserver { observer: subscriber.observer, count: self.count, queue: VecDeque::new(), }, subscription: subscriber.subscription, }; self.source.actual_subscribe(subscriber) } } observable_proxy_impl!(SkipLastOp, S); impl<'a, Item: 'a, S> LocalObservable<'a> for SkipLastOp<S> where S: LocalObservable<'a, Item = Item>, { type Unsub = S::Unsub; observable_impl!(LocalSubscription, 'a); } impl<S> SharedObservable for SkipLastOp<S> where S: SharedObservable, S::Item: Send + Sync + 'static, { type Unsub = S::Unsub; observable_impl!(SharedSubscription, Send + Sync + 'static); } pub struct SkipLastObserver<O, Item> { observer: O, count: usize, queue: VecDeque<Item>, } impl<Item, Err, O> Observer<Item, Err> for SkipLastObserver<O, Item> where O: Observer<Item, Err>, { fn next(&mut self, value: Item) { self.queue.push_back(value); } error_proxy_impl!(Err, observer); fn complete(&mut self) { if self.count <= self.queue.len() { let skip_index = self.queue.len() - self.count; for value in self.queue.drain(..skip_index) { 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..10) .skip_last(5) .subscribe_complete(|v| ticks.push(v), || completed = true); assert_eq!(ticks, vec![0, 1, 2, 3, 4]); assert_eq!(completed, true); } #[test] fn base_empty_function() { let mut completed = false; let mut ticks = vec![]; observable::from_iter(0..10) .skip_last(11) .subscribe_complete(|v| ticks.push(v), || completed = true); assert_eq!(ticks, vec![]); assert_eq!(completed, true); } #[test] fn skip_last_support_fork() { let mut nc1 = 0; let mut nc2 = 0; { let skip_last5 = observable::from_iter(0..100).skip_last(5); let f1 = skip_last5.clone(); let f2 = skip_last5; f1.skip_last(5).subscribe(|_| nc1 += 1); f2.skip_last(5).subscribe(|_| nc2 += 1); } assert_eq!(nc1, 90); assert_eq!(nc2, 90); } #[test] fn into_shared() { observable::from_iter(0..100) .skip_last(5) .skip_last(5) .to_shared() .subscribe(|_| {}); } }