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Diffstat (limited to 'vendor/futures-util/src/stream/try_stream/mod.rs')
| -rw-r--r-- | vendor/futures-util/src/stream/try_stream/mod.rs | 1064 |
1 files changed, 1064 insertions, 0 deletions
diff --git a/vendor/futures-util/src/stream/try_stream/mod.rs b/vendor/futures-util/src/stream/try_stream/mod.rs new file mode 100644 index 000000000..455ddca3f --- /dev/null +++ b/vendor/futures-util/src/stream/try_stream/mod.rs @@ -0,0 +1,1064 @@ +//! Streams +//! +//! This module contains a number of functions for working with `Streams`s +//! that return `Result`s, allowing for short-circuiting computations. + +#[cfg(feature = "compat")] +use crate::compat::Compat; +use crate::fns::{ + inspect_err_fn, inspect_ok_fn, into_fn, map_err_fn, map_ok_fn, InspectErrFn, InspectOkFn, + IntoFn, MapErrFn, MapOkFn, +}; +use crate::future::assert_future; +use crate::stream::assert_stream; +use crate::stream::{Inspect, Map}; +#[cfg(feature = "alloc")] +use alloc::vec::Vec; +use core::pin::Pin; +use futures_core::{ + future::{Future, TryFuture}, + stream::TryStream, + task::{Context, Poll}, +}; + +mod and_then; +#[allow(unreachable_pub)] // https://github.com/rust-lang/rust/issues/57411 +pub use self::and_then::AndThen; + +delegate_all!( + /// Stream for the [`err_into`](super::TryStreamExt::err_into) method. + ErrInto<St, E>( + MapErr<St, IntoFn<E>> + ): Debug + Sink + Stream + FusedStream + AccessInner[St, (.)] + New[|x: St| MapErr::new(x, into_fn())] +); + +delegate_all!( + /// Stream for the [`inspect_ok`](super::TryStreamExt::inspect_ok) method. + InspectOk<St, F>( + Inspect<IntoStream<St>, InspectOkFn<F>> + ): Debug + Sink + Stream + FusedStream + AccessInner[St, (. .)] + New[|x: St, f: F| Inspect::new(IntoStream::new(x), inspect_ok_fn(f))] +); + +delegate_all!( + /// Stream for the [`inspect_err`](super::TryStreamExt::inspect_err) method. + InspectErr<St, F>( + Inspect<IntoStream<St>, InspectErrFn<F>> + ): Debug + Sink + Stream + FusedStream + AccessInner[St, (. .)] + New[|x: St, f: F| Inspect::new(IntoStream::new(x), inspect_err_fn(f))] +); + +mod into_stream; +#[allow(unreachable_pub)] // https://github.com/rust-lang/rust/issues/57411 +pub use self::into_stream::IntoStream; + +delegate_all!( + /// Stream for the [`map_ok`](super::TryStreamExt::map_ok) method. + MapOk<St, F>( + Map<IntoStream<St>, MapOkFn<F>> + ): Debug + Sink + Stream + FusedStream + AccessInner[St, (. .)] + New[|x: St, f: F| Map::new(IntoStream::new(x), map_ok_fn(f))] +); + +delegate_all!( + /// Stream for the [`map_err`](super::TryStreamExt::map_err) method. + MapErr<St, F>( + Map<IntoStream<St>, MapErrFn<F>> + ): Debug + Sink + Stream + FusedStream + AccessInner[St, (. .)] + New[|x: St, f: F| Map::new(IntoStream::new(x), map_err_fn(f))] +); + +mod or_else; +#[allow(unreachable_pub)] // https://github.com/rust-lang/rust/issues/57411 +pub use self::or_else::OrElse; + +mod try_next; +#[allow(unreachable_pub)] // https://github.com/rust-lang/rust/issues/57411 +pub use self::try_next::TryNext; + +mod try_for_each; +#[allow(unreachable_pub)] // https://github.com/rust-lang/rust/issues/57411 +pub use self::try_for_each::TryForEach; + +mod try_filter; +#[allow(unreachable_pub)] // https://github.com/rust-lang/rust/issues/57411 +pub use self::try_filter::TryFilter; + +mod try_filter_map; +#[allow(unreachable_pub)] // https://github.com/rust-lang/rust/issues/57411 +pub use self::try_filter_map::TryFilterMap; + +mod try_flatten; +#[allow(unreachable_pub)] // https://github.com/rust-lang/rust/issues/57411 +pub use self::try_flatten::TryFlatten; + +mod try_collect; +#[allow(unreachable_pub)] // https://github.com/rust-lang/rust/issues/57411 +pub use self::try_collect::TryCollect; + +mod try_concat; +#[allow(unreachable_pub)] // https://github.com/rust-lang/rust/issues/57411 +pub use self::try_concat::TryConcat; + +#[cfg(feature = "alloc")] +mod try_chunks; +#[cfg(feature = "alloc")] +#[allow(unreachable_pub)] // https://github.com/rust-lang/rust/issues/57411 +pub use self::try_chunks::{TryChunks, TryChunksError}; + +mod try_fold; +#[allow(unreachable_pub)] // https://github.com/rust-lang/rust/issues/57411 +pub use self::try_fold::TryFold; + +mod try_unfold; +#[allow(unreachable_pub)] // https://github.com/rust-lang/rust/issues/57411 +pub use self::try_unfold::{try_unfold, TryUnfold}; + +mod try_skip_while; +#[allow(unreachable_pub)] // https://github.com/rust-lang/rust/issues/57411 +pub use self::try_skip_while::TrySkipWhile; + +mod try_take_while; +#[allow(unreachable_pub)] // https://github.com/rust-lang/rust/issues/57411 +pub use self::try_take_while::TryTakeWhile; + +#[cfg(not(futures_no_atomic_cas))] +#[cfg(feature = "alloc")] +mod try_buffer_unordered; +#[cfg(not(futures_no_atomic_cas))] +#[cfg(feature = "alloc")] +#[allow(unreachable_pub)] // https://github.com/rust-lang/rust/issues/57411 +pub use self::try_buffer_unordered::TryBufferUnordered; + +#[cfg(not(futures_no_atomic_cas))] +#[cfg(feature = "alloc")] +mod try_buffered; +#[cfg(not(futures_no_atomic_cas))] +#[cfg(feature = "alloc")] +#[allow(unreachable_pub)] // https://github.com/rust-lang/rust/issues/57411 +pub use self::try_buffered::TryBuffered; + +#[cfg(not(futures_no_atomic_cas))] +#[cfg(feature = "alloc")] +mod try_for_each_concurrent; +#[cfg(not(futures_no_atomic_cas))] +#[cfg(feature = "alloc")] +#[allow(unreachable_pub)] // https://github.com/rust-lang/rust/issues/57411 +pub use self::try_for_each_concurrent::TryForEachConcurrent; + +#[cfg(feature = "io")] +#[cfg(feature = "std")] +mod into_async_read; +#[cfg(feature = "io")] +#[cfg_attr(docsrs, doc(cfg(feature = "io")))] +#[cfg(feature = "std")] +#[allow(unreachable_pub)] // https://github.com/rust-lang/rust/issues/57411 +pub use self::into_async_read::IntoAsyncRead; + +impl<S: ?Sized + TryStream> TryStreamExt for S {} + +/// Adapters specific to `Result`-returning streams +pub trait TryStreamExt: TryStream { + /// Wraps the current stream in a new stream which converts the error type + /// into the one provided. + /// + /// # Examples + /// + /// ``` + /// # futures::executor::block_on(async { + /// use futures::stream::{self, TryStreamExt}; + /// + /// let mut stream = + /// stream::iter(vec![Ok(()), Err(5i32)]) + /// .err_into::<i64>(); + /// + /// assert_eq!(stream.try_next().await, Ok(Some(()))); + /// assert_eq!(stream.try_next().await, Err(5i64)); + /// # }) + /// ``` + fn err_into<E>(self) -> ErrInto<Self, E> + where + Self: Sized, + Self::Error: Into<E>, + { + assert_stream::<Result<Self::Ok, E>, _>(ErrInto::new(self)) + } + + /// Wraps the current stream in a new stream which maps the success value + /// using the provided closure. + /// + /// # Examples + /// + /// ``` + /// # futures::executor::block_on(async { + /// use futures::stream::{self, TryStreamExt}; + /// + /// let mut stream = + /// stream::iter(vec![Ok(5), Err(0)]) + /// .map_ok(|x| x + 2); + /// + /// assert_eq!(stream.try_next().await, Ok(Some(7))); + /// assert_eq!(stream.try_next().await, Err(0)); + /// # }) + /// ``` + fn map_ok<T, F>(self, f: F) -> MapOk<Self, F> + where + Self: Sized, + F: FnMut(Self::Ok) -> T, + { + assert_stream::<Result<T, Self::Error>, _>(MapOk::new(self, f)) + } + + /// Wraps the current stream in a new stream which maps the error value + /// using the provided closure. + /// + /// # Examples + /// + /// ``` + /// # futures::executor::block_on(async { + /// use futures::stream::{self, TryStreamExt}; + /// + /// let mut stream = + /// stream::iter(vec![Ok(5), Err(0)]) + /// .map_err(|x| x + 2); + /// + /// assert_eq!(stream.try_next().await, Ok(Some(5))); + /// assert_eq!(stream.try_next().await, Err(2)); + /// # }) + /// ``` + fn map_err<E, F>(self, f: F) -> MapErr<Self, F> + where + Self: Sized, + F: FnMut(Self::Error) -> E, + { + assert_stream::<Result<Self::Ok, E>, _>(MapErr::new(self, f)) + } + + /// Chain on a computation for when a value is ready, passing the successful + /// results to the provided closure `f`. + /// + /// This function can be used to run a unit of work when the next successful + /// value on a stream is ready. The closure provided will be yielded a value + /// when ready, and the returned future will then be run to completion to + /// produce the next value on this stream. + /// + /// Any errors produced by this stream will not be passed to the closure, + /// and will be passed through. + /// + /// The returned value of the closure must implement the `TryFuture` trait + /// and can represent some more work to be done before the composed stream + /// is finished. + /// + /// Note that this function consumes the receiving stream and returns a + /// wrapped version of it. + /// + /// To process the entire stream and return a single future representing + /// success or error, use `try_for_each` instead. + /// + /// # Examples + /// + /// ``` + /// use futures::channel::mpsc; + /// use futures::future; + /// use futures::stream::TryStreamExt; + /// + /// let (_tx, rx) = mpsc::channel::<Result<i32, ()>>(1); + /// + /// let rx = rx.and_then(|result| { + /// future::ok(if result % 2 == 0 { + /// Some(result) + /// } else { + /// None + /// }) + /// }); + /// ``` + fn and_then<Fut, F>(self, f: F) -> AndThen<Self, Fut, F> + where + F: FnMut(Self::Ok) -> Fut, + Fut: TryFuture<Error = Self::Error>, + Self: Sized, + { + assert_stream::<Result<Fut::Ok, Fut::Error>, _>(AndThen::new(self, f)) + } + + /// Chain on a computation for when an error happens, passing the + /// erroneous result to the provided closure `f`. + /// + /// This function can be used to run a unit of work and attempt to recover from + /// an error if one happens. The closure provided will be yielded an error + /// when one appears, and the returned future will then be run to completion + /// to produce the next value on this stream. + /// + /// Any successful values produced by this stream will not be passed to the + /// closure, and will be passed through. + /// + /// The returned value of the closure must implement the [`TryFuture`](futures_core::future::TryFuture) trait + /// and can represent some more work to be done before the composed stream + /// is finished. + /// + /// Note that this function consumes the receiving stream and returns a + /// wrapped version of it. + fn or_else<Fut, F>(self, f: F) -> OrElse<Self, Fut, F> + where + F: FnMut(Self::Error) -> Fut, + Fut: TryFuture<Ok = Self::Ok>, + Self: Sized, + { + assert_stream::<Result<Self::Ok, Fut::Error>, _>(OrElse::new(self, f)) + } + + /// Do something with the success value of this stream, afterwards passing + /// it on. + /// + /// This is similar to the `StreamExt::inspect` method where it allows + /// easily inspecting the success value as it passes through the stream, for + /// example to debug what's going on. + fn inspect_ok<F>(self, f: F) -> InspectOk<Self, F> + where + F: FnMut(&Self::Ok), + Self: Sized, + { + assert_stream::<Result<Self::Ok, Self::Error>, _>(InspectOk::new(self, f)) + } + + /// Do something with the error value of this stream, afterwards passing it on. + /// + /// This is similar to the `StreamExt::inspect` method where it allows + /// easily inspecting the error value as it passes through the stream, for + /// example to debug what's going on. + fn inspect_err<F>(self, f: F) -> InspectErr<Self, F> + where + F: FnMut(&Self::Error), + Self: Sized, + { + assert_stream::<Result<Self::Ok, Self::Error>, _>(InspectErr::new(self, f)) + } + + /// Wraps a [`TryStream`] into a type that implements + /// [`Stream`](futures_core::stream::Stream) + /// + /// [`TryStream`]s currently do not implement the + /// [`Stream`](futures_core::stream::Stream) trait because of limitations + /// of the compiler. + /// + /// # Examples + /// + /// ``` + /// use futures::stream::{Stream, TryStream, TryStreamExt}; + /// + /// # type T = i32; + /// # type E = (); + /// fn make_try_stream() -> impl TryStream<Ok = T, Error = E> { // ... } + /// # futures::stream::empty() + /// # } + /// fn take_stream(stream: impl Stream<Item = Result<T, E>>) { /* ... */ } + /// + /// take_stream(make_try_stream().into_stream()); + /// ``` + fn into_stream(self) -> IntoStream<Self> + where + Self: Sized, + { + assert_stream::<Result<Self::Ok, Self::Error>, _>(IntoStream::new(self)) + } + + /// Creates a future that attempts to resolve the next item in the stream. + /// If an error is encountered before the next item, the error is returned + /// instead. + /// + /// This is similar to the `Stream::next` combinator, but returns a + /// `Result<Option<T>, E>` rather than an `Option<Result<T, E>>`, making + /// for easy use with the `?` operator. + /// + /// # Examples + /// + /// ``` + /// # futures::executor::block_on(async { + /// use futures::stream::{self, TryStreamExt}; + /// + /// let mut stream = stream::iter(vec![Ok(()), Err(())]); + /// + /// assert_eq!(stream.try_next().await, Ok(Some(()))); + /// assert_eq!(stream.try_next().await, Err(())); + /// # }) + /// ``` + fn try_next(&mut self) -> TryNext<'_, Self> + where + Self: Unpin, + { + assert_future::<Result<Option<Self::Ok>, Self::Error>, _>(TryNext::new(self)) + } + + /// Attempts to run this stream to completion, executing the provided + /// asynchronous closure for each element on the stream. + /// + /// The provided closure 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`](futures_core::future::Future) where the + /// [`Output`](futures_core::future::Future::Output) type is + /// `Result<(), Self::Error>`. If any of the intermediate + /// futures or the stream returns an error, this future will return + /// immediately with an error. + /// + /// # Examples + /// + /// ``` + /// # futures::executor::block_on(async { + /// use futures::future; + /// use futures::stream::{self, TryStreamExt}; + /// + /// let mut x = 0i32; + /// + /// { + /// let fut = stream::repeat(Ok(1)).try_for_each(|item| { + /// x += item; + /// future::ready(if x == 3 { Err(()) } else { Ok(()) }) + /// }); + /// assert_eq!(fut.await, Err(())); + /// } + /// + /// assert_eq!(x, 3); + /// # }) + /// ``` + fn try_for_each<Fut, F>(self, f: F) -> TryForEach<Self, Fut, F> + where + F: FnMut(Self::Ok) -> Fut, + Fut: TryFuture<Ok = (), Error = Self::Error>, + Self: Sized, + { + assert_future::<Result<(), Self::Error>, _>(TryForEach::new(self, f)) + } + + /// Skip elements on this stream while the provided asynchronous predicate + /// resolves to `true`. + /// + /// This function is similar to + /// [`StreamExt::skip_while`](crate::stream::StreamExt::skip_while) but exits + /// early if an error occurs. + /// + /// # Examples + /// + /// ``` + /// # futures::executor::block_on(async { + /// use futures::future; + /// use futures::stream::{self, TryStreamExt}; + /// + /// let stream = stream::iter(vec![Ok::<i32, i32>(1), Ok(3), Ok(2)]); + /// let stream = stream.try_skip_while(|x| future::ready(Ok(*x < 3))); + /// + /// let output: Result<Vec<i32>, i32> = stream.try_collect().await; + /// assert_eq!(output, Ok(vec![3, 2])); + /// # }) + /// ``` + fn try_skip_while<Fut, F>(self, f: F) -> TrySkipWhile<Self, Fut, F> + where + F: FnMut(&Self::Ok) -> Fut, + Fut: TryFuture<Ok = bool, Error = Self::Error>, + Self: Sized, + { + assert_stream::<Result<Self::Ok, Self::Error>, _>(TrySkipWhile::new(self, f)) + } + + /// Take elements on this stream while the provided asynchronous predicate + /// resolves to `true`. + /// + /// This function is similar to + /// [`StreamExt::take_while`](crate::stream::StreamExt::take_while) but exits + /// early if an error occurs. + /// + /// # Examples + /// + /// ``` + /// # futures::executor::block_on(async { + /// use futures::future; + /// use futures::stream::{self, TryStreamExt}; + /// + /// let stream = stream::iter(vec![Ok::<i32, i32>(1), Ok(2), Ok(3), Ok(2)]); + /// let stream = stream.try_take_while(|x| future::ready(Ok(*x < 3))); + /// + /// let output: Result<Vec<i32>, i32> = stream.try_collect().await; + /// assert_eq!(output, Ok(vec![1, 2])); + /// # }) + /// ``` + fn try_take_while<Fut, F>(self, f: F) -> TryTakeWhile<Self, Fut, F> + where + F: FnMut(&Self::Ok) -> Fut, + Fut: TryFuture<Ok = bool, Error = Self::Error>, + Self: Sized, + { + assert_stream::<Result<Self::Ok, Self::Error>, _>(TryTakeWhile::new(self, f)) + } + + /// Attempts to run this stream to completion, executing the provided asynchronous + /// closure for each element on the stream concurrently as elements become + /// available, exiting as soon as an error occurs. + /// + /// This is similar to + /// [`StreamExt::for_each_concurrent`](crate::stream::StreamExt::for_each_concurrent), + /// but will resolve to an error immediately if the underlying stream or the provided + /// closure return an error. + /// + /// This method is only available when the `std` or `alloc` feature of this + /// library is activated, and it is activated by default. + /// + /// # Examples + /// + /// ``` + /// # futures::executor::block_on(async { + /// use futures::channel::oneshot; + /// use futures::stream::{self, StreamExt, TryStreamExt}; + /// + /// let (tx1, rx1) = oneshot::channel(); + /// let (tx2, rx2) = oneshot::channel(); + /// let (_tx3, rx3) = oneshot::channel(); + /// + /// let stream = stream::iter(vec![rx1, rx2, rx3]); + /// let fut = stream.map(Ok).try_for_each_concurrent( + /// /* limit */ 2, + /// |rx| async move { + /// let res: Result<(), oneshot::Canceled> = rx.await; + /// res + /// } + /// ); + /// + /// tx1.send(()).unwrap(); + /// // Drop the second sender so that `rx2` resolves to `Canceled`. + /// drop(tx2); + /// + /// // The final result is an error because the second future + /// // resulted in an error. + /// assert_eq!(Err(oneshot::Canceled), fut.await); + /// # }) + /// ``` + #[cfg(not(futures_no_atomic_cas))] + #[cfg(feature = "alloc")] + fn try_for_each_concurrent<Fut, F>( + self, + limit: impl Into<Option<usize>>, + f: F, + ) -> TryForEachConcurrent<Self, Fut, F> + where + F: FnMut(Self::Ok) -> Fut, + Fut: Future<Output = Result<(), Self::Error>>, + Self: Sized, + { + assert_future::<Result<(), Self::Error>, _>(TryForEachConcurrent::new( + self, + limit.into(), + f, + )) + } + + /// Attempt to transform a stream into a collection, + /// returning a future representing the result of that computation. + /// + /// This combinator will collect all successful results of this stream and + /// collect them into the specified collection type. If an error happens then all + /// collected elements will be dropped and the error will be returned. + /// + /// The returned future will be resolved when the stream terminates. + /// + /// # Examples + /// + /// ``` + /// # futures::executor::block_on(async { + /// use futures::channel::mpsc; + /// use futures::stream::TryStreamExt; + /// use std::thread; + /// + /// let (tx, rx) = mpsc::unbounded(); + /// + /// thread::spawn(move || { + /// for i in 1..=5 { + /// tx.unbounded_send(Ok(i)).unwrap(); + /// } + /// tx.unbounded_send(Err(6)).unwrap(); + /// }); + /// + /// let output: Result<Vec<i32>, i32> = rx.try_collect().await; + /// assert_eq!(output, Err(6)); + /// # }) + /// ``` + fn try_collect<C: Default + Extend<Self::Ok>>(self) -> TryCollect<Self, C> + where + Self: Sized, + { + assert_future::<Result<C, Self::Error>, _>(TryCollect::new(self)) + } + + /// An adaptor for chunking up successful items of the stream inside a vector. + /// + /// This combinator will attempt to pull successful items from this stream and buffer + /// them into a local vector. At most `capacity` items will get buffered + /// before they're yielded from the returned stream. + /// + /// Note that the vectors returned from this iterator may not always have + /// `capacity` elements. If the underlying stream ended and only a partial + /// vector was created, it'll be returned. Additionally if an error happens + /// from the underlying stream then the currently buffered items will be + /// yielded. + /// + /// This method is only available when the `std` or `alloc` feature of this + /// library is activated, and it is activated by default. + /// + /// This function is similar to + /// [`StreamExt::chunks`](crate::stream::StreamExt::chunks) but exits + /// early if an error occurs. + /// + /// # Examples + /// + /// ``` + /// # futures::executor::block_on(async { + /// use futures::stream::{self, TryChunksError, TryStreamExt}; + /// + /// let stream = stream::iter(vec![Ok::<i32, i32>(1), Ok(2), Ok(3), Err(4), Ok(5), Ok(6)]); + /// let mut stream = stream.try_chunks(2); + /// + /// assert_eq!(stream.try_next().await, Ok(Some(vec![1, 2]))); + /// assert_eq!(stream.try_next().await, Err(TryChunksError(vec![3], 4))); + /// assert_eq!(stream.try_next().await, Ok(Some(vec![5, 6]))); + /// # }) + /// ``` + /// + /// # Panics + /// + /// This method will panic if `capacity` is zero. + #[cfg(feature = "alloc")] + fn try_chunks(self, capacity: usize) -> TryChunks<Self> + where + Self: Sized, + { + assert_stream::<Result<Vec<Self::Ok>, TryChunksError<Self::Ok, Self::Error>>, _>( + TryChunks::new(self, capacity), + ) + } + + /// Attempt to filter the values produced by this stream according to the + /// provided asynchronous closure. + /// + /// As values of this stream are made available, the provided predicate `f` + /// will be run on them. If the predicate returns a `Future` which resolves + /// to `true`, then the stream will yield the value, but if the predicate + /// return a `Future` which resolves to `false`, then the value will be + /// discarded and the next value will be produced. + /// + /// All errors are passed through without filtering in this combinator. + /// + /// 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::future; + /// use futures::stream::{self, StreamExt, TryStreamExt}; + /// + /// let stream = stream::iter(vec![Ok(1i32), Ok(2i32), Ok(3i32), Err("error")]); + /// let mut evens = stream.try_filter(|x| { + /// future::ready(x % 2 == 0) + /// }); + /// + /// assert_eq!(evens.next().await, Some(Ok(2))); + /// assert_eq!(evens.next().await, Some(Err("error"))); + /// # }) + /// ``` + fn try_filter<Fut, F>(self, f: F) -> TryFilter<Self, Fut, F> + where + Fut: Future<Output = bool>, + F: FnMut(&Self::Ok) -> Fut, + Self: Sized, + { + assert_stream::<Result<Self::Ok, Self::Error>, _>(TryFilter::new(self, f)) + } + + /// Attempt to filter 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. + /// + /// All errors are passed through without filtering in this combinator. + /// + /// 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::stream::{self, StreamExt, TryStreamExt}; + /// use futures::pin_mut; + /// + /// let stream = stream::iter(vec![Ok(1i32), Ok(6i32), Err("error")]); + /// let halves = stream.try_filter_map(|x| async move { + /// let ret = if x % 2 == 0 { Some(x / 2) } else { None }; + /// Ok(ret) + /// }); + /// + /// pin_mut!(halves); + /// assert_eq!(halves.next().await, Some(Ok(3))); + /// assert_eq!(halves.next().await, Some(Err("error"))); + /// # }) + /// ``` + fn try_filter_map<Fut, F, T>(self, f: F) -> TryFilterMap<Self, Fut, F> + where + Fut: TryFuture<Ok = Option<T>, Error = Self::Error>, + F: FnMut(Self::Ok) -> Fut, + Self: Sized, + { + assert_stream::<Result<T, Self::Error>, _>(TryFilterMap::new(self, f)) + } + + /// Flattens a stream of streams into just one continuous stream. + /// + /// If this stream's elements are themselves streams then this combinator + /// will flatten out the entire stream to one long chain of elements. Any + /// errors are passed through without looking at them, but otherwise each + /// individual stream will get exhausted before moving on to the next. + /// + /// # Examples + /// + /// ``` + /// # futures::executor::block_on(async { + /// use futures::channel::mpsc; + /// use futures::stream::{StreamExt, TryStreamExt}; + /// use std::thread; + /// + /// let (tx1, rx1) = mpsc::unbounded(); + /// let (tx2, rx2) = mpsc::unbounded(); + /// let (tx3, rx3) = mpsc::unbounded(); + /// + /// thread::spawn(move || { + /// tx1.unbounded_send(Ok(1)).unwrap(); + /// }); + /// thread::spawn(move || { + /// tx2.unbounded_send(Ok(2)).unwrap(); + /// tx2.unbounded_send(Err(3)).unwrap(); + /// }); + /// thread::spawn(move || { + /// tx3.unbounded_send(Ok(rx1)).unwrap(); + /// tx3.unbounded_send(Ok(rx2)).unwrap(); + /// tx3.unbounded_send(Err(4)).unwrap(); + /// }); + /// + /// let mut stream = rx3.try_flatten(); + /// assert_eq!(stream.next().await, Some(Ok(1))); + /// assert_eq!(stream.next().await, Some(Ok(2))); + /// assert_eq!(stream.next().await, Some(Err(3))); + /// # }); + /// ``` + fn try_flatten(self) -> TryFlatten<Self> + where + Self::Ok: TryStream, + <Self::Ok as TryStream>::Error: From<Self::Error>, + Self: Sized, + { + assert_stream::<Result<<Self::Ok as TryStream>::Ok, <Self::Ok as TryStream>::Error>, _>( + TryFlatten::new(self), + ) + } + + /// Attempt to 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. + /// + /// This method is similar to [`fold`](crate::stream::StreamExt::fold), but will + /// exit early if an error is encountered in either the stream or the + /// provided closure. + /// + /// # Examples + /// + /// ``` + /// # futures::executor::block_on(async { + /// use futures::stream::{self, TryStreamExt}; + /// + /// let number_stream = stream::iter(vec![Ok::<i32, i32>(1), Ok(2)]); + /// let sum = number_stream.try_fold(0, |acc, x| async move { Ok(acc + x) }); + /// assert_eq!(sum.await, Ok(3)); + /// + /// let number_stream_with_err = stream::iter(vec![Ok::<i32, i32>(1), Err(2), Ok(1)]); + /// let sum = number_stream_with_err.try_fold(0, |acc, x| async move { Ok(acc + x) }); + /// assert_eq!(sum.await, Err(2)); + /// # }) + /// ``` + fn try_fold<T, Fut, F>(self, init: T, f: F) -> TryFold<Self, Fut, T, F> + where + F: FnMut(T, Self::Ok) -> Fut, + Fut: TryFuture<Ok = T, Error = Self::Error>, + Self: Sized, + { + assert_future::<Result<T, Self::Error>, _>(TryFold::new(self, f, init)) + } + + /// Attempt to 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 successful 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. + /// + /// This method is similar to [`concat`](crate::stream::StreamExt::concat), but will + /// exit early if an error is encountered in the stream. + /// + /// # Examples + /// + /// ``` + /// # futures::executor::block_on(async { + /// use futures::channel::mpsc; + /// use futures::stream::TryStreamExt; + /// use std::thread; + /// + /// let (tx, rx) = mpsc::unbounded::<Result<Vec<i32>, ()>>(); + /// + /// thread::spawn(move || { + /// for i in (0..3).rev() { + /// let n = i * 3; + /// tx.unbounded_send(Ok(vec![n + 1, n + 2, n + 3])).unwrap(); + /// } + /// }); + /// + /// let result = rx.try_concat().await; + /// + /// assert_eq!(result, Ok(vec![7, 8, 9, 4, 5, 6, 1, 2, 3])); + /// # }); + /// ``` + fn try_concat(self) -> TryConcat<Self> + where + Self: Sized, + Self::Ok: Extend<<<Self as TryStream>::Ok as IntoIterator>::Item> + IntoIterator + Default, + { + assert_future::<Result<Self::Ok, Self::Error>, _>(TryConcat::new(self)) + } + + /// Attempt to execute several futures from a stream concurrently (unordered). + /// + /// This stream's `Ok` type must be a [`TryFuture`](futures_core::future::TryFuture) with an `Error` type + /// that matches the stream's `Error` type. + /// + /// This adaptor will buffer up to `n` futures and then return their + /// outputs in the order in which they complete. If the underlying stream + /// returns an error, it will be immediately propagated. + /// + /// The returned stream will be a stream of results, each containing either + /// an error or a future's output. An error can be produced either by the + /// underlying stream itself or by one of the futures it yielded. + /// + /// This method is only available when the `std` or `alloc` feature of this + /// library is activated, and it is activated by default. + /// + /// # Examples + /// + /// Results are returned in the order of completion: + /// ``` + /// # futures::executor::block_on(async { + /// use futures::channel::oneshot; + /// use futures::stream::{self, StreamExt, TryStreamExt}; + /// + /// let (send_one, recv_one) = oneshot::channel(); + /// let (send_two, recv_two) = oneshot::channel(); + /// + /// let stream_of_futures = stream::iter(vec![Ok(recv_one), Ok(recv_two)]); + /// + /// let mut buffered = stream_of_futures.try_buffer_unordered(10); + /// + /// send_two.send(2i32)?; + /// assert_eq!(buffered.next().await, Some(Ok(2i32))); + /// + /// send_one.send(1i32)?; + /// assert_eq!(buffered.next().await, Some(Ok(1i32))); + /// + /// assert_eq!(buffered.next().await, None); + /// # Ok::<(), i32>(()) }).unwrap(); + /// ``` + /// + /// Errors from the underlying stream itself are propagated: + /// ``` + /// # futures::executor::block_on(async { + /// use futures::channel::mpsc; + /// use futures::stream::{StreamExt, TryStreamExt}; + /// + /// let (sink, stream_of_futures) = mpsc::unbounded(); + /// let mut buffered = stream_of_futures.try_buffer_unordered(10); + /// + /// sink.unbounded_send(Ok(async { Ok(7i32) }))?; + /// assert_eq!(buffered.next().await, Some(Ok(7i32))); + /// + /// sink.unbounded_send(Err("error in the stream"))?; + /// assert_eq!(buffered.next().await, Some(Err("error in the stream"))); + /// # Ok::<(), Box<dyn std::error::Error>>(()) }).unwrap(); + /// ``` + #[cfg(not(futures_no_atomic_cas))] + #[cfg(feature = "alloc")] + fn try_buffer_unordered(self, n: usize) -> TryBufferUnordered<Self> + where + Self::Ok: TryFuture<Error = Self::Error>, + Self: Sized, + { + assert_stream::<Result<<Self::Ok as TryFuture>::Ok, Self::Error>, _>( + TryBufferUnordered::new(self, n), + ) + } + + /// Attempt to execute several futures from a stream concurrently. + /// + /// This stream's `Ok` type must be a [`TryFuture`](futures_core::future::TryFuture) with an `Error` type + /// that matches the stream's `Error` type. + /// + /// This adaptor will buffer up to `n` futures and then return their + /// outputs in the order. If the underlying stream returns an error, it will + /// be immediately propagated. + /// + /// The returned stream will be a stream of results, each containing either + /// an error or a future's output. An error can be produced either by the + /// underlying stream itself or by one of the futures it yielded. + /// + /// This method is only available when the `std` or `alloc` feature of this + /// library is activated, and it is activated by default. + /// + /// # Examples + /// + /// Results are returned in the order of addition: + /// ``` + /// # futures::executor::block_on(async { + /// use futures::channel::oneshot; + /// use futures::future::lazy; + /// use futures::stream::{self, StreamExt, TryStreamExt}; + /// + /// let (send_one, recv_one) = oneshot::channel(); + /// let (send_two, recv_two) = oneshot::channel(); + /// + /// let mut buffered = lazy(move |cx| { + /// let stream_of_futures = stream::iter(vec![Ok(recv_one), Ok(recv_two)]); + /// + /// let mut buffered = stream_of_futures.try_buffered(10); + /// + /// assert!(buffered.try_poll_next_unpin(cx).is_pending()); + /// + /// send_two.send(2i32)?; + /// assert!(buffered.try_poll_next_unpin(cx).is_pending()); + /// Ok::<_, i32>(buffered) + /// }).await?; + /// + /// send_one.send(1i32)?; + /// assert_eq!(buffered.next().await, Some(Ok(1i32))); + /// assert_eq!(buffered.next().await, Some(Ok(2i32))); + /// + /// assert_eq!(buffered.next().await, None); + /// # Ok::<(), i32>(()) }).unwrap(); + /// ``` + /// + /// Errors from the underlying stream itself are propagated: + /// ``` + /// # futures::executor::block_on(async { + /// use futures::channel::mpsc; + /// use futures::stream::{StreamExt, TryStreamExt}; + /// + /// let (sink, stream_of_futures) = mpsc::unbounded(); + /// let mut buffered = stream_of_futures.try_buffered(10); + /// + /// sink.unbounded_send(Ok(async { Ok(7i32) }))?; + /// assert_eq!(buffered.next().await, Some(Ok(7i32))); + /// + /// sink.unbounded_send(Err("error in the stream"))?; + /// assert_eq!(buffered.next().await, Some(Err("error in the stream"))); + /// # Ok::<(), Box<dyn std::error::Error>>(()) }).unwrap(); + /// ``` + #[cfg(not(futures_no_atomic_cas))] + #[cfg(feature = "alloc")] + fn try_buffered(self, n: usize) -> TryBuffered<Self> + where + Self::Ok: TryFuture<Error = Self::Error>, + Self: Sized, + { + assert_stream::<Result<<Self::Ok as TryFuture>::Ok, Self::Error>, _>(TryBuffered::new( + self, n, + )) + } + + // TODO: false positive warning from rustdoc. Verify once #43466 settles + // + /// A convenience method for calling [`TryStream::try_poll_next`] on [`Unpin`] + /// stream types. + fn try_poll_next_unpin( + &mut self, + cx: &mut Context<'_>, + ) -> Poll<Option<Result<Self::Ok, Self::Error>>> + where + Self: Unpin, + { + Pin::new(self).try_poll_next(cx) + } + + /// Wraps a [`TryStream`] into a stream compatible with libraries using + /// futures 0.1 `Stream`. Requires the `compat` feature to be enabled. + /// ``` + /// use futures::future::{FutureExt, TryFutureExt}; + /// # let (tx, rx) = futures::channel::oneshot::channel(); + /// + /// let future03 = async { + /// println!("Running on the pool"); + /// tx.send(42).unwrap(); + /// }; + /// + /// let future01 = future03 + /// .unit_error() // Make it a TryFuture + /// .boxed() // Make it Unpin + /// .compat(); + /// + /// tokio::run(future01); + /// # assert_eq!(42, futures::executor::block_on(rx).unwrap()); + /// ``` + #[cfg(feature = "compat")] + #[cfg_attr(docsrs, doc(cfg(feature = "compat")))] + fn compat(self) -> Compat<Self> + where + Self: Sized + Unpin, + { + Compat::new(self) + } + + /// Adapter that converts this stream into an [`AsyncRead`](crate::io::AsyncRead). + /// + /// Note that because `into_async_read` moves the stream, the [`Stream`](futures_core::stream::Stream) type must be + /// [`Unpin`]. If you want to use `into_async_read` 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. + /// + /// This method is only available when the `std` feature of this + /// library is activated, and it is activated by default. + /// + /// # Examples + /// + /// ``` + /// # futures::executor::block_on(async { + /// use futures::stream::{self, TryStreamExt}; + /// use futures::io::AsyncReadExt; + /// + /// let stream = stream::iter(vec![Ok(vec![1, 2, 3, 4, 5])]); + /// let mut reader = stream.into_async_read(); + /// let mut buf = Vec::new(); + /// + /// assert!(reader.read_to_end(&mut buf).await.is_ok()); + /// assert_eq!(buf, &[1, 2, 3, 4, 5]); + /// # }) + /// ``` + #[cfg(feature = "io")] + #[cfg_attr(docsrs, doc(cfg(feature = "io")))] + #[cfg(feature = "std")] + fn into_async_read(self) -> IntoAsyncRead<Self> + where + Self: Sized + TryStreamExt<Error = std::io::Error> + Unpin, + Self::Ok: AsRef<[u8]>, + { + crate::io::assert_read(IntoAsyncRead::new(self)) + } +} |