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use core::future::Future; pub use futures_core::stream::Stream; use core::iter::IntoIterator; use core::pin::Pin; use core::task::{Context, Poll}; use pin_utils::pin_mut; /// Creates a future that resolves to the next item in the stream. /// /// Note that because `next` doesn't take ownership over the stream, /// the [`Stream`] type must be [`Unpin`]. If you want to use `next` with a /// [`!Unpin`](Unpin) stream, you'll first have to pin the stream. This can /// be done by boxing the stream using [`Box::pin`] or /// pinning it to the stack using the `pin_mut!` macro from the `pin_utils` /// crate. /// /// # Examples /// /// ``` /// # futures::executor::block_on(async { /// use futures_async_combinators::stream::{iter, next}; /// /// let mut stream = iter(1..=3); /// /// assert_eq!(next(&mut stream).await, Some(1)); /// assert_eq!(next(&mut stream).await, Some(2)); /// assert_eq!(next(&mut stream).await, Some(3)); /// assert_eq!(next(&mut stream).await, None); /// # }); /// ``` pub fn next<'a, St>(mut stream: &'a mut St) -> impl Future<Output = Option<St::Item>> + 'a where St: Stream + Unpin, { use crate::future::poll_fn; poll_fn(move |context| Pin::new(&mut stream).poll_next(context)) } /// Collect all of the values of this stream into a vector, returning a /// future representing the result of that computation. /// /// The returned future will be resolved when the stream terminates. /// /// # Examples /// /// ``` /// # futures::executor::block_on(async { /// use futures_async_combinators::stream::{iter, collect}; /// /// let stream = iter(1..=5); /// /// let collection: Vec<i32> = collect(stream).await; /// assert_eq!(collection, vec![1, 2, 3, 4, 5]); /// # }); /// ``` pub async fn collect<St, C>(stream: St) -> C where St: Stream, C: Default + Extend<St::Item>, { pin_mut!(stream); let mut collection = C::default(); while let Some(item) = next(&mut stream).await { collection.extend(Some(item)); } collection } /// Maps this stream's items to a different type, returning a new stream of /// the resulting type. /// /// The provided closure is executed over all elements of this stream as /// they are made available. It is executed inline with calls to /// [`poll_next`](Stream::poll_next). /// /// Note that this function consumes the stream passed into it and returns a /// wrapped version of it, similar to the existing `map` methods in the /// standard library. /// /// # Examples /// /// ``` /// # futures::executor::block_on(async { /// use futures_async_combinators::stream::{iter, map, collect}; /// /// let stream = iter(1..=3); /// let stream = map(stream, |x| x + 3); /// /// let result: Vec<_> = collect(stream).await; /// assert_eq!(vec![4, 5, 6], result); /// # }); /// ``` pub fn map<St, U, F>(stream: St, f: F) -> impl Stream<Item = U> where St: Stream, F: FnMut(St::Item) -> U, { let stream = Box::pin(stream); unfold((stream, f), async move |(mut stream, mut f)| { let item = next(&mut stream).await; item.map(|item| (f(item), (stream, f))) }) } /// Filters the values produced by this stream according to the provided /// asynchronous predicate. /// /// As values of this stream are made available, the provided predicate `f` /// will be run against them. If the predicate returns a `Future` which /// resolves to `true`, then the stream will yield the value, but if the /// predicate returns a `Future` which resolves to `false`, then the value /// will be discarded and the next value will be produced. /// /// Note that this function consumes the stream passed into it and returns a /// wrapped version of it, similar to the existing `filter` methods in the /// standard library. /// /// # Examples /// /// ``` /// # futures::executor::block_on(async { /// use futures_async_combinators::{future::ready, stream::{iter, filter, collect}}; /// /// let stream = iter(1..=10); /// let evens = filter(stream, |x| ready(x % 2 == 0)); /// /// let result: Vec<_> = collect(evens).await; /// assert_eq!(vec![2, 4, 6, 8, 10], result); /// # }); /// ``` pub fn filter<St, Fut, F>(stream: St, f: F) -> impl Stream<Item = St::Item> where St: Stream, F: FnMut(&St::Item) -> Fut, Fut: Future<Output = bool>, { let stream = Box::pin(stream); unfold((stream, f), async move |(mut stream, mut f)| { while let Some(item) = next(&mut stream).await { let matched = f(&item).await; if matched { return Some((item, (stream, f))); } else { continue; } } None }) } /// Filters the values produced by this stream while simultaneously mapping /// them to a different type according to the provided asynchronous closure. /// /// As values of this stream are made available, the provided function will /// be run on them. If the future returned by the predicate `f` resolves to /// [`Some(item)`](Some) then the stream will yield the value `item`, but if /// it resolves to [`None`] then the next value will be produced. /// /// Note that this function consumes the stream passed into it and returns a /// wrapped version of it, similar to the existing `filter_map` methods in /// the standard library. /// /// # Examples /// ``` /// # futures::executor::block_on(async { /// use futures_async_combinators::{future::ready, stream::{iter, filter_map, collect}}; /// /// let stream = iter(1..=10); /// let evens = filter_map(stream, |x| { /// let ret = if x % 2 == 0 { Some(x + 1) } else { None }; /// ready(ret) /// }); /// /// let result: Vec<_> = collect(evens).await; /// assert_eq!(vec![3, 5, 7, 9, 11], result); /// # }); /// ``` pub fn filter_map<St, Fut, F, U>(stream: St, f: F) -> impl Stream<Item = U> where St: Stream, F: FnMut(St::Item) -> Fut, Fut: Future<Output = Option<U>>, { let stream = Box::pin(stream); unfold((stream, f), async move |(mut stream, mut f)| { while let Some(item) = next(&mut stream).await { if let Some(item) = f(item).await { return Some((item, (stream, f))); } else { continue; } } None }) } /// Converts this stream into a future of `(next_item, tail_of_stream)`. /// If the stream terminates, then the next item is [`None`]. /// /// The returned future can be used to compose streams and futures together /// by placing everything into the "world of futures". /// /// Note that because `into_future` moves the stream, the [`Stream`] type /// must be [`Unpin`]. If you want to use `into_future` with a /// [`!Unpin`](Unpin) stream, you'll first have to pin the stream. This can /// be done by boxing the stream using [`Box::pin`] or /// pinning it to the stack using the `pin_mut!` macro from the `pin_utils` /// crate. /// /// # Examples /// /// ``` /// # futures::executor::block_on(async { /// use futures_async_combinators::stream::{iter, into_future}; /// /// let stream = iter(1..3); /// /// let (item, stream) = into_future(stream).await; /// assert_eq!(Some(1), item); /// /// let (item, stream) = into_future(stream).await; /// assert_eq!(Some(2), item); /// /// let (item, stream) = into_future(stream).await; /// assert_eq!(None, item); /// # }); /// ``` pub async fn into_future<St>(stream: St) -> (Option<St::Item>, impl Stream<Item = St::Item>) where St: Stream + Unpin, { let mut stream = stream; let next_item = next(&mut stream).await; (next_item, stream) } /// Converts an `Iterator` into a `Stream` which is always ready /// to yield the next value. /// /// Iterators in Rust don't express the ability to block, so this adapter /// simply always calls `iter.next()` and returns that. /// /// ``` /// # futures::executor::block_on(async { /// use futures_async_combinators::stream::{iter, collect}; /// /// let stream = iter(vec![17, 19]); /// let result: Vec<_> = collect(stream).await; /// assert_eq!(vec![17, 19], result); /// # }); /// ``` pub fn iter<I>(i: I) -> impl Stream<Item = I::Item> where I: IntoIterator, { let mut iter = i.into_iter(); crate::stream::poll_fn(move |_| -> Poll<Option<I::Item>> { Poll::Ready(iter.next()) }) } /// Concatenate all items of a stream into a single extendable /// destination, returning a future representing the end result. /// /// This combinator will extend the first item with the contents /// of all the subsequent results of the stream. If the stream is /// empty, the default value will be returned. /// /// Works with all collections that implement the /// [`Extend`](std::iter::Extend) trait. /// /// # Examples /// /// ``` /// # futures::executor::block_on(async { /// use futures_async_combinators::stream::{iter, concat}; /// /// let stream = iter(vec![vec![1, 2], vec![3], vec![4, 5]]); /// /// let result: Vec<_> = concat(stream).await; /// assert_eq!(result, vec![1, 2, 3, 4, 5]); /// # }); /// ``` pub async fn concat<St>(stream: St) -> St::Item where St: Stream, St::Item: Extend<<St::Item as IntoIterator>::Item>, St::Item: IntoIterator, St::Item: Default, { pin_mut!(stream); let mut collection = <St::Item>::default(); while let Some(item) = next(&mut stream).await { collection.extend(item); } collection } /// Runs this stream to completion, executing the provided asynchronous /// closure for each element on the stream. /// /// The closure provided will be called for each item this stream produces, /// yielding a future. That future will then be executed to completion /// before moving on to the next item. /// /// The returned value is a `Future` where the `Output` type is `()`; it is /// executed entirely for its side effects. /// /// To process each item in the stream and produce another stream instead /// of a single future, use `then` instead. /// /// # Examples /// /// ``` /// # futures::executor::block_on(async { /// use futures::future; /// use futures_async_combinators::{future::ready, stream::{repeat, take, for_each}}; /// /// let mut x = 0; /// /// { /// let stream = repeat(1); /// let stream = take(stream, 3); /// let fut = for_each(stream, |item| { /// x += item; /// ready(()) /// }); /// fut.await; /// } /// /// assert_eq!(x, 3); /// # }); /// ``` pub async fn for_each<St, Fut, F>(stream: St, f: F) -> () where St: Stream, F: FnMut(St::Item) -> Fut, Fut: Future<Output = ()>, { pin_mut!(stream); let mut f = f; while let Some(item) = next(&mut stream).await { f(item); } } /// Creates a new stream of at most `n` items of the underlying stream. /// /// Once `n` items have been yielded from this stream then it will always /// return that the stream is done. /// /// # Examples /// /// ``` /// # futures::executor::block_on(async { /// use futures_async_combinators::stream::{iter, take, collect}; /// /// let stream = iter(1..=10); /// let stream = take(stream, 3); /// /// let result: Vec<_> = collect(stream).await; /// assert_eq!(vec![1, 2, 3], result); /// # }); /// ``` pub fn take<St>(stream: St, n: u64) -> impl Stream<Item = St::Item> where St: Stream, { let stream = Box::pin(stream); unfold((stream, n), async move |(mut stream, n)| { if n == 0 { None } else { if let Some(item) = next(&mut stream).await { Some((item, (stream, n - 1))) } else { None } } }) } /// Create a stream which produces the same item repeatedly. /// /// The stream never terminates. Note that you likely want to avoid /// usage of `collect` or such on the returned stream as it will exhaust /// available memory as it tries to just fill up all RAM. /// /// ``` /// # futures::executor::block_on(async { /// use futures_async_combinators::stream::{repeat, take, collect}; /// /// let stream = repeat(9); /// let stream = take(stream, 3); /// /// let result: Vec<_> = collect(stream).await; /// assert_eq!(vec![9, 9, 9], result); /// # }); /// ``` pub fn repeat<T>(item: T) -> impl Stream<Item = T> where T: Clone, { crate::stream::poll_fn(move |_| -> Poll<Option<T>> { Poll::Ready(Some(item.clone())) }) } /// Flattens a stream of streams into just one continuous stream. /// /// # Examples /// /// ``` /// # futures::executor::block_on(async { /// use futures_async_combinators::stream::{iter, flatten, collect}; /// /// let stream0 = iter(0..0); /// let stream1 = iter(1..4); /// let stream2 = iter(4..7); /// let stream3 = iter(7..10); /// let stream = iter(vec![stream0, stream1, stream2, stream3]); /// let stream = flatten(stream); /// /// let result: Vec<_> = collect(stream).await; /// assert_eq!(vec![1, 2, 3, 4, 5, 6, 7, 8, 9], result); /// # }); /// ``` pub fn flatten<St, SubSt, T>(stream: St) -> impl Stream<Item = T> where SubSt: Stream<Item = T>, St: Stream<Item = SubSt>, { let stream = Box::pin(stream); unfold( (Some(stream), None), async move |(mut state_stream, mut state_substream)| loop { if let Some(mut substream) = state_substream.take() { if let Some(item) = next(&mut substream).await { return Some((item, (state_stream, Some(substream)))); } else { continue; } } if let Some(mut stream) = state_stream.take() { if let Some(substream) = next(&mut stream).await { let substream = Box::pin(substream); state_stream = Some(stream); state_substream = Some(substream); continue; } } return None; }, ) } /// Computes from this stream's items new items of a different type using /// an asynchronous closure. /// /// The provided closure `f` will be called with an `Item` once a value is /// ready, it returns a future which will then be run to completion /// to produce the next value on this stream. /// /// Note that this function consumes the stream passed into it and returns a /// wrapped version of it. /// /// # Examples /// /// ``` /// # futures::executor::block_on(async { /// use futures_async_combinators::{future::ready, stream::{iter, then, collect}}; /// /// let stream = iter(1..=3); /// let stream = then(stream, |x| ready(x + 3)); /// /// let result: Vec<_> = collect(stream).await; /// assert_eq!(vec![4, 5, 6], result); /// # }); /// ``` pub fn then<St, F, Fut>(stream: St, f: F) -> impl Stream<Item = St::Item> where St: Stream, F: FnMut(St::Item) -> Fut, Fut: Future<Output = St::Item>, { let stream = Box::pin(stream); unfold((stream, f), async move |(mut stream, mut f)| { let item = next(&mut stream).await; if let Some(item) = item { let new_item = f(item).await; Some((new_item, (stream, f))) } else { None } }) } /// Creates a new stream which skips `n` items of the underlying stream. /// /// Once `n` items have been skipped from this stream then it will always /// return the remaining items on this stream. /// /// # Examples /// /// ``` /// # futures::executor::block_on(async { /// use futures_async_combinators::stream::{iter, skip, collect}; /// /// let stream = iter(1..=10); /// let stream = skip(stream, 5); /// /// let result: Vec<_> = collect(stream).await; /// assert_eq!(vec![6, 7, 8, 9, 10], result); /// # }); /// ``` pub fn skip<St>(stream: St, n: u64) -> impl Stream<Item = St::Item> where St: Stream, { let stream = Box::pin(stream); unfold((stream, n), async move |(mut stream, mut n)| { while n != 0 { if let Some(_) = next(&mut stream).await { n = n - 1; continue; } else { return None; } } if let Some(item) = next(&mut stream).await { Some((item, (stream, 0))) } else { None } }) } /// An adapter for zipping two streams together. /// /// The zipped stream waits for both streams to produce an item, and then /// returns that pair. If either stream ends then the zipped stream will /// also end. /// /// # Examples /// /// ``` /// # futures::executor::block_on(async { /// use futures_async_combinators::stream::{iter, zip, collect}; /// /// let stream1 = iter(1..=3); /// let stream2 = iter(5..=10); /// /// let stream = zip(stream1, stream2); /// let result: Vec<_> = collect(stream).await; /// assert_eq!(vec![(1, 5), (2, 6), (3, 7)], result); /// # }); /// ``` /// pub fn zip<St1, St2>(stream: St1, other: St2) -> impl Stream<Item = (St1::Item, St2::Item)> where St1: Stream, St2: Stream, { let stream = Box::pin(stream); let other = Box::pin(other); unfold((stream, other), async move |(mut stream, mut other)| { let left = next(&mut stream).await; let right = next(&mut other).await; match (left, right) { (Some(left), Some(right)) => Some(((left, right), (stream, other))), _ => None, } }) } /// Adapter for chaining two stream. /// /// The resulting stream emits elements from the first stream, and when /// first stream reaches the end, emits the elements from the second stream. /// /// ``` /// # futures::executor::block_on(async { /// use futures_async_combinators::stream::{iter, chain, collect}; /// /// let stream1 = iter(vec![Ok(10), Err(false)]); /// let stream2 = iter(vec![Err(true), Ok(20)]); /// /// let stream = chain(stream1, stream2); /// /// let result: Vec<_> = collect(stream).await; /// assert_eq!(result, vec![ /// Ok(10), /// Err(false), /// Err(true), /// Ok(20), /// ]); /// # }); /// ``` pub fn chain<St>(stream: St, other: St) -> impl Stream<Item = St::Item> where St: Stream, { let stream = Box::pin(stream); let other = Box::pin(other); let start_with_first = true; unfold( (stream, other, start_with_first), async move |(mut stream, mut other, start_with_first)| { if start_with_first { if let Some(item) = next(&mut stream).await { return Some((item, (stream, other, start_with_first))); } } if let Some(item) = next(&mut other).await { Some((item, (stream, other, /* start_with_first */ false))) } else { None } }, ) } /// Take elements from this stream while the provided asynchronous predicate /// resolves to `true`. /// /// This function, like `Iterator::take_while`, will take elements from the /// stream until the predicate `f` resolves to `false`. Once one element /// returns false it will always return that the stream is done. /// /// # Examples /// /// ``` /// # futures::executor::block_on(async { /// use futures_async_combinators::{future::ready, stream::{iter, take_while, collect}}; /// /// let stream = iter(1..=10); /// let stream = take_while(stream, |x| ready(*x <= 5)); /// /// let result: Vec<_> = collect(stream).await; /// assert_eq!(vec![1, 2, 3, 4, 5], result); /// # }); /// ``` pub fn take_while<St, F, Fut>(stream: St, f: F) -> impl Stream<Item = St::Item> where St: Stream, F: FnMut(&St::Item) -> Fut, Fut: Future<Output = bool>, { let stream = Box::pin(stream); unfold((stream, f), async move |(mut stream, mut f)| { if let Some(item) = next(&mut stream).await { if f(&item).await { Some((item, (stream, f))) } else { None } } else { None } }) } /// Skip elements on this stream while the provided asynchronous predicate /// resolves to `true`. /// /// This function, like `Iterator::skip_while`, will skip elements on the /// stream until the predicate `f` resolves to `false`. Once one element /// returns false all future elements will be returned from the underlying /// stream. /// /// # Examples /// /// ``` /// # futures::executor::block_on(async { /// use futures_async_combinators::{future::ready, stream::{iter, skip_while, collect}}; /// /// let stream = iter(1..=10); /// let stream = skip_while(stream, |x| ready(*x <= 5)); /// /// let result: Vec<_> = collect(stream).await; /// assert_eq!(vec![6, 7, 8, 9, 10], result); /// # }); /// ``` pub fn skip_while<St, F, Fut>(stream: St, f: F) -> impl Stream<Item = St::Item> where St: Stream, F: FnMut(&St::Item) -> Fut, Fut: Future<Output = bool>, { let stream = Box::pin(stream); let should_skip = true; unfold( (stream, f, should_skip), async move |(mut stream, mut f, should_skip)| { while should_skip { if let Some(item) = next(&mut stream).await { if f(&item).await { continue; } else { return Some((item, (stream, f, /* should_skip */ false))); } } else { return None; } } if let Some(item) = next(&mut stream).await { Some((item, (stream, f, /* should_skip */ false))) } else { None } }, ) } /// Execute an accumulating asynchronous computation over a stream, /// collecting all the values into one final result. /// /// This combinator will accumulate all values returned by this stream /// according to the closure provided. The initial state is also provided to /// this method and then is returned again by each execution of the closure. /// Once the entire stream has been exhausted the returned future will /// resolve to this value. /// /// # Examples /// /// ``` /// # futures::executor::block_on(async { /// use futures_async_combinators::{future::ready, stream::{iter, fold}}; /// /// let number_stream = iter(0..6); /// let sum = fold(number_stream, 0, |acc, x| ready(acc + x)); /// assert_eq!(sum.await, 15); /// # }); /// ``` pub async fn fold<St, T, F, Fut>(stream: St, init: T, f: F) -> T where St: Stream, F: FnMut(T, St::Item) -> Fut, Fut: Future<Output = T>, { pin_mut!(stream); let mut f = f; let mut acc = init; while let Some(item) = next(&mut stream).await { acc = f(acc, item).await; } acc } /// Creates a `Stream` from a seed and a closure returning a `Future`. /// /// This function is the dual for the [`fold()`] adapter: while /// [`fold()`] reduces a `Stream` to one single value, `unfold()` creates a /// `Stream` from a seed value. /// /// `unfold()` will call the provided closure with the provided seed, then wait /// for the returned `Future` to complete with `(a, b)`. It will then yield the /// value `a`, and use `b` as the next internal state. /// /// If the closure returns `None` instead of `Some(Future)`, then the `unfold()` /// will stop producing items and return `Poll::Ready(None)` in future /// calls to `poll()`. /// /// In case of error generated by the returned `Future`, the error will be /// returned by the `Stream`. The `Stream` will then yield /// `Poll::Ready(None)` in future calls to `poll()`. /// /// This function can typically be used when wanting to go from the "world of /// futures" to the "world of streams": the provided closure can build a /// `Future` using other library functions working on futures, and `unfold()` /// will turn it into a `Stream` by repeating the operation. /// /// # Example /// /// ``` /// # futures::executor::block_on(async { /// use futures_async_combinators::{future::ready, stream::{unfold, collect}}; /// /// let stream = unfold(0, |state| { /// if state <= 2 { /// let next_state = state + 1; /// let yielded = state * 2; /// ready(Some((yielded, next_state))) /// } else { /// ready(None) /// } /// }); /// /// let result: Vec<_> = collect(stream).await; /// assert_eq!(result, vec![0, 2, 4]); /// # }); /// ``` pub fn unfold<T, F, Fut, It>(init: T, mut f: F) -> impl Stream<Item = It> where F: FnMut(T) -> Fut, Fut: Future<Output = Option<(It, T)>>, { enum State<T, Fut> { Paused(T), Running(Pin<Box<Fut>>), } let mut state = Some(State::Paused(init)); crate::stream::poll_fn(move |context| -> Poll<Option<It>> { let mut future = match state.take() { Some(State::Running(fut)) => fut, Some(State::Paused(st)) => Box::pin(f(st)), None => panic!("this stream must not be polled any more"), }; match future.as_mut().poll(context) { Poll::Pending => { state = Some(State::Running(future)); Poll::Pending } Poll::Ready(None) => Poll::Ready(None), Poll::Ready(Some((item, new_state))) => { state = Some(State::Paused(new_state)); Poll::Ready(Some(item)) } } }) } /// Creates a new stream wrapping a function returning `Poll<Option<T>>`. /// /// Polling the returned stream calls the wrapped function. /// /// # Examples /// /// ``` /// use futures_async_combinators::stream::poll_fn; /// use core::task::Poll; /// /// let mut counter = 1usize; /// /// let read_stream = poll_fn(move |_| -> Poll<Option<String>> { /// if counter == 0 { return Poll::Ready(None); } /// counter -= 1; /// Poll::Ready(Some("Hello, World!".to_owned())) /// }); /// ``` pub fn poll_fn<T, F>(f: F) -> impl Stream<Item = T> where F: FnMut(&mut Context<'_>) -> Poll<Option<T>>, { pub struct PollFn<F> { f: F, } impl<F> Unpin for PollFn<F> {} impl<T, F> Stream for PollFn<F> where F: FnMut(&mut Context<'_>) -> Poll<Option<T>>, { type Item = T; fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<T>> { (&mut self.f)(cx) } } PollFn { f } } #[cfg(test)] mod tests { use crate::future::ready; use crate::stream::*; use futures::executor; #[test] fn test_next() { let mut stream = iter(1..=3); assert_eq!(executor::block_on(next(&mut stream)), Some(1)); assert_eq!(executor::block_on(next(&mut stream)), Some(2)); assert_eq!(executor::block_on(next(&mut stream)), Some(3)); assert_eq!(executor::block_on(next(&mut stream)), None); } #[test] fn test_collect() { let stream = iter(1..=5); let collection: Vec<i32> = executor::block_on(collect(stream)); assert_eq!(collection, vec![1, 2, 3, 4, 5]); } #[test] fn test_map() { let stream = iter(1..=3); let stream = map(stream, |x| x * 2); assert_eq!( vec![2, 4, 6], executor::block_on(collect::<_, Vec<_>>(stream)) ); } #[test] fn test_filter() { let stream = iter(1..=10); let evens = filter(stream, |x| ready(x % 2 == 0)); assert_eq!( vec![2, 4, 6, 8, 10], executor::block_on(collect::<_, Vec<_>>(evens)) ); } #[test] fn test_filter_map() { let stream = iter(1..=10); let evens = filter_map(stream, |x| { let ret = if x % 2 == 0 { Some(x + 1) } else { None }; ready(ret) }); assert_eq!( vec![3, 5, 7, 9, 11], executor::block_on(collect::<_, Vec<_>>(evens)) ); } #[test] fn test_into_future() { let stream = iter(1..=2); let (item, stream) = executor::block_on(into_future(stream)); assert_eq!(Some(1), item); let (item, stream) = executor::block_on(into_future(stream)); assert_eq!(Some(2), item); let (item, _) = executor::block_on(into_future(stream)); assert_eq!(None, item); } #[test] fn test_iter() { let stream = iter(1..=5); let collection: Vec<i32> = executor::block_on(collect(stream)); assert_eq!(collection, vec![1, 2, 3, 4, 5]); } #[test] fn test_concat() { let stream = iter(vec![vec![1, 2], vec![3], vec![4, 5]]); let collection: Vec<i32> = executor::block_on(concat(stream)); assert_eq!(collection, vec![1, 2, 3, 4, 5]); } #[test] fn test_for_each() { let mut x = 0; { let stream = iter(1..=3); let future = for_each(stream, |item| { x += item; ready(()) }); executor::block_on(future); } assert_eq!(x, 6); } #[test] fn test_take() { let stream = iter(1..=10); let stream = take(stream, 3); assert_eq!( vec![1, 2, 3], executor::block_on(collect::<_, Vec<_>>(stream)) ); } #[test] fn test_take_more_than_size() { let stream = iter(1..=3); let stream = take(stream, 10); assert_eq!( vec![1, 2, 3], executor::block_on(collect::<_, Vec<_>>(stream)) ); } #[test] fn test_repeat() { let stream = repeat(9); let stream = take(stream, 3); assert_eq!( vec![9, 9, 9], executor::block_on(collect::<_, Vec<_>>(stream)) ); } #[test] fn test_flatten() { let stream0 = iter(0..0); let stream1 = iter(1..4); let stream2 = iter(4..7); let stream3 = iter(7..10); let stream = iter(vec![stream0, stream1, stream2, stream3]); let stream = flatten(stream); assert_eq!( vec![1, 2, 3, 4, 5, 6, 7, 8, 9], executor::block_on(collect::<_, Vec<_>>(stream)) ); } #[test] fn test_then() { let stream = iter(1..=3); let stream = then(stream, |x| ready(x + 3)); assert_eq!( vec![4, 5, 6], executor::block_on(collect::<_, Vec<_>>(stream)) ); } #[test] fn test_skip() { let stream = iter(1..=10); let stream = skip(stream, 5); assert_eq!( vec![6, 7, 8, 9, 10], executor::block_on(collect::<_, Vec<_>>(stream)) ); } #[test] fn test_skip_more_than_size() { let stream = iter(1..=10); let stream = skip(stream, 15); assert!(executor::block_on(collect::<_, Vec<_>>(stream)).is_empty()); } #[test] fn test_zip() { let stream1 = iter(1..=3); let stream2 = iter(5..=10); let stream = zip(stream1, stream2); assert_eq!( vec![(1, 5), (2, 6), (3, 7)], executor::block_on(collect::<_, Vec<_>>(stream)) ); } #[test] fn test_chain() { let stream1 = iter(1..=2); let stream2 = iter(3..=4); let stream = chain(stream1, stream2); assert_eq!( vec![1, 2, 3, 4], executor::block_on(collect::<_, Vec<_>>(stream)) ); } #[test] fn test_take_while() { let stream = iter(1..=10); let stream = take_while(stream, |x| ready(*x <= 5)); assert_eq!( vec![1, 2, 3, 4, 5], executor::block_on(collect::<_, Vec<_>>(stream)) ); } #[test] fn test_take_while_more_than_size() { let stream = iter(1..=3); let stream = take_while(stream, |x| ready(*x <= 5)); assert_eq!( vec![1, 2, 3], executor::block_on(collect::<_, Vec<_>>(stream)) ); } #[test] fn test_skip_while() { let stream = iter(1..=10); let stream = skip_while(stream, |x| ready(*x <= 5)); assert_eq!( vec![6, 7, 8, 9, 10], executor::block_on(collect::<_, Vec<_>>(stream)) ); } #[test] fn test_skip_while_more_than_size() { let stream = iter(1..=3); let stream = skip_while(stream, |x| ready(*x <= 5)); assert!(executor::block_on(collect::<_, Vec<_>>(stream)).is_empty()); } #[test] fn test_fold() { let stream = iter(0..6); let sum = fold(stream, 0, |acc, x| ready(acc + x)); assert_eq!(15, executor::block_on(sum)); } #[test] fn test_unfold() { let stream = unfold(0, |state| { if state <= 2 { let next_state = state + 1; let yielded = state * 2; ready(Some((yielded, next_state))) } else { ready(None) } }); assert_eq!( vec![0, 2, 4], executor::block_on(collect::<_, Vec<_>>(stream)) ); } }