Struct futures::stream::MapErr

#[must_use = "streams do nothing unless polled"]
pub struct MapErr<S, F> { /* fields omitted */ }

A stream combinator which will change the error type of a stream from one type to another.

This is produced by the Stream::map_err method.

Methods

impl<S, F> MapErr<S, F>

pub fn get_ref(&self) -> &S

Acquires a reference to the underlying stream that this combinator is pulling from.

pub fn get_mut(&mut self) -> &mut S

Acquires a mutable reference to the underlying stream that this combinator is pulling from.

Note that care must be taken to avoid tampering with the state of the stream which may otherwise confuse this combinator.

pub fn into_inner(self) -> S

Consumes this combinator, returning the underlying stream.

Note that this may discard intermediate state of this combinator, so care should be taken to avoid losing resources when this is called.

Trait Implementations

impl<S, F, U> Stream for MapErr<S, F> where
    S: Stream,
    F: FnMut(S::Error) -> U, 

type Item = S::Item

The type of item this stream will yield on success.

type Error = U

The type of error this stream may generate.

fn poll(&mut self) -> Poll<Option<S::Item>, U>

Attempt to pull out the next value of this stream, returning None if the stream is finished.

Important traits for Wait<S>

impl<S: Stream> Iterator for Wait<S> type Item = Result<S::Item, S::Error>;

fn wait(self) -> Wait<Self> where
    Self: Sized, 

Creates an iterator which blocks the current thread until each item of this stream is resolved.

fn into_future(self) -> StreamFuture<Self> where
    Self: Sized, 

Converts this stream into a Future.

fn map<U, F>(self, f: F) -> Map<Self, F> where
    F: FnMut(Self::Item) -> U,
    Self: Sized, 

Converts a stream of type T to a stream of type U.

fn map_err<U, F>(self, f: F) -> MapErr<Self, F> where
    F: FnMut(Self::Error) -> U,
    Self: Sized, 

Converts a stream of error type T to a stream of error type U.

fn filter<F>(self, f: F) -> Filter<Self, F> where
    F: FnMut(&Self::Item) -> bool,
    Self: Sized, 

Filters the values produced by this stream according to the provided predicate.

fn filter_map<F, B>(self, f: F) -> FilterMap<Self, F> where
    F: FnMut(Self::Item) -> Option<B>,
    Self: Sized, 

Filters the values produced by this stream while simultaneously mapping them to a different type.

fn then<F, U>(self, f: F) -> Then<Self, F, U> where
    F: FnMut(Result<Self::Item, Self::Error>) -> U,
    U: IntoFuture,
    Self: Sized, 

Chain on a computation for when a value is ready, passing the resulting item to the provided closure f.

fn and_then<F, U>(self, f: F) -> AndThen<Self, F, U> where
    F: FnMut(Self::Item) -> U,
    U: IntoFuture<Error = Self::Error>,
    Self: Sized, 

Chain on a computation for when a value is ready, passing the successful results to the provided closure f.

fn or_else<F, U>(self, f: F) -> OrElse<Self, F, U> where
    F: FnMut(Self::Error) -> U,
    U: IntoFuture<Item = Self::Item>,
    Self: Sized, 

Chain on a computation for when an error happens, passing the erroneous result to the provided closure f.

fn collect(self) -> Collect<Self> where
    Self: Sized, 

Collect all of the values of this stream into a vector, returning a future representing the result of that computation.

fn concat2(self) -> Concat2<Self> where
    Self: Sized,
    Self::Item: Extend<<Self::Item as IntoIterator>::Item> + IntoIterator + Default, 

Concatenate all results of a stream into a single extendable destination, returning a future representing the end result.

fn concat(self) -> Concat<Self> where
    Self: Sized,
    Self::Item: Extend<<Self::Item as IntoIterator>::Item> + IntoIterator, 

Deprecated since 0.1.14:

please use Stream::concat2 instead

Concatenate all results of a stream into a single extendable destination, returning a future representing the end result.

fn fold<F, T, Fut>(self, init: T, f: F) -> Fold<Self, F, Fut, T> where
    F: FnMut(T, Self::Item) -> Fut,
    Fut: IntoFuture<Item = T>,
    Self::Error: From<Fut::Error>,
    Self: Sized, 

Execute an accumulating computation over a stream, collecting all the values into one final result.

fn flatten(self) -> Flatten<Self> where
    Self::Item: Stream,
    <Self::Item as Stream>::Error: From<Self::Error>,
    Self: Sized, 

Flattens a stream of streams into just one continuous stream.

fn skip_while<P, R>(self, pred: P) -> SkipWhile<Self, P, R> where
    P: FnMut(&Self::Item) -> R,
    R: IntoFuture<Item = bool, Error = Self::Error>,
    Self: Sized, 

Skip elements on this stream while the predicate provided resolves to true.

fn take_while<P, R>(self, pred: P) -> TakeWhile<Self, P, R> where
    P: FnMut(&Self::Item) -> R,
    R: IntoFuture<Item = bool, Error = Self::Error>,
    Self: Sized, 

Take elements from this stream while the predicate provided resolves to true.

fn for_each<F, U>(self, f: F) -> ForEach<Self, F, U> where
    F: FnMut(Self::Item) -> U,
    U: IntoFuture<Item = (), Error = Self::Error>,
    Self: Sized, 

Runs this stream to completion, executing the provided closure for each element on the stream.

fn from_err<E: From<Self::Error>>(self) -> FromErr<Self, E> where
    Self: Sized, 

Map this stream's error to any error implementing From for this stream's Error, returning a new stream.

fn take(self, amt: u64) -> Take<Self> where
    Self: Sized, 

Creates a new stream of at most amt items of the underlying stream.

fn skip(self, amt: u64) -> Skip<Self> where
    Self: Sized, 

Creates a new stream which skips amt items of the underlying stream.

fn fuse(self) -> Fuse<Self> where
    Self: Sized, 

Fuse a stream such that poll will never again be called once it has finished.

fn by_ref(&mut self) -> &mut Self where
    Self: Sized, 

Borrows a stream, rather than consuming it.

fn catch_unwind(self) -> CatchUnwind<Self> where
    Self: Sized + UnwindSafe, 

Catches unwinding panics while polling the stream.

fn buffered(self, amt: usize) -> Buffered<Self> where
    Self::Item: IntoFuture<Error = Self::Error>,
    Self: Sized, 

An adaptor for creating a buffered list of pending futures.

fn buffer_unordered(self, amt: usize) -> BufferUnordered<Self> where
    Self::Item: IntoFuture<Error = Self::Error>,
    Self: Sized, 

An adaptor for creating a buffered list of pending futures (unordered).

fn merge<S>(self, other: S) -> Merge<Self, S> where
    S: Stream<Error = Self::Error>,
    Self: Sized, 

Deprecated:

functionality provided by select now

An adapter for merging the output of two streams.

fn zip<S>(self, other: S) -> Zip<Self, S> where
    S: Stream<Error = Self::Error>,
    Self: Sized, 

An adapter for zipping two streams together.

fn chain<S>(self, other: S) -> Chain<Self, S> where
    S: Stream<Item = Self::Item, Error = Self::Error>,
    Self: Sized, 

Adapter for chaining two stream.

fn peekable(self) -> Peekable<Self> where
    Self: Sized, 

Creates a new stream which exposes a peek method.

fn chunks(self, capacity: usize) -> Chunks<Self> where
    Self: Sized, 

An adaptor for chunking up items of the stream inside a vector.

fn select<S>(self, other: S) -> Select<Self, S> where
    S: Stream<Item = Self::Item, Error = Self::Error>,
    Self: Sized, 

Creates a stream that selects the next element from either this stream or the provided one, whichever is ready first.

fn forward<S>(self, sink: S) -> Forward<Self, S> where
    S: Sink<SinkItem = Self::Item>,
    Self::Error: From<S::SinkError>,
    Self: Sized, 

A future that completes after the given stream has been fully processed into the sink, including flushing.

fn split(self) -> (SplitSink<Self>, SplitStream<Self>) where
    Self: Sink + Sized, 

Splits this Stream + Sink object into separate Stream and Sink objects.

fn inspect<F>(self, f: F) -> Inspect<Self, F> where
    F: FnMut(&Self::Item),
    Self: Sized, 

Do something with each item of this stream, afterwards passing it on.

fn inspect_err<F>(self, f: F) -> InspectErr<Self, F> where
    F: FnMut(&Self::Error),
    Self: Sized, 

Do something with the error of this stream, afterwards passing it on.

impl<S, F> Sink for MapErr<S, F> where
    S: Sink, 

type SinkItem = S::SinkItem

The type of value that the sink accepts.

type SinkError = S::SinkError

The type of value produced by the sink when an error occurs.

fn start_send(
    &mut self,
    item: S::SinkItem
) -> StartSend<S::SinkItem, S::SinkError>

Begin the process of sending a value to the sink.

fn poll_complete(&mut self) -> Poll<(), S::SinkError>

Flush all output from this sink, if necessary.

fn close(&mut self) -> Poll<(), S::SinkError>

A method to indicate that no more values will ever be pushed into this sink.

fn wait(self) -> Wait<Self> where
    Self: Sized, 

Creates a new object which will produce a synchronous sink.

fn with<U, F, Fut>(self, f: F) -> With<Self, U, F, Fut> where
    F: FnMut(U) -> Fut,
    Fut: IntoFuture<Item = Self::SinkItem>,
    Fut::Error: From<Self::SinkError>,
    Self: Sized, 

Composes a function in front of the sink.

fn with_flat_map<U, F, St>(self, f: F) -> WithFlatMap<Self, U, F, St> where
    F: FnMut(U) -> St,
    St: Stream<Item = Self::SinkItem, Error = Self::SinkError>,
    Self: Sized, 

Composes a function in front of the sink.

fn sink_map_err<F, E>(self, f: F) -> SinkMapErr<Self, F> where
    F: FnOnce(Self::SinkError) -> E,
    Self: Sized, 

Transforms the error returned by the sink.

fn sink_from_err<E: From<Self::SinkError>>(self) -> SinkFromErr<Self, E> where
    Self: Sized, 

Map this sink's error to any error implementing From for this sink's Error, returning a new sink.

fn buffer(self, amt: usize) -> Buffer<Self> where
    Self: Sized, 

Adds a fixed-size buffer to the current sink.

fn fanout<S>(self, other: S) -> Fanout<Self, S> where
    Self: Sized,
    Self::SinkItem: Clone,
    S: Sink<SinkItem = Self::SinkItem, SinkError = Self::SinkError>, 

Fanout items to multiple sinks.

fn flush(self) -> Flush<Self> where
    Self: Sized, 

A future that completes when the sink has finished processing all pending requests.

fn send(self, item: Self::SinkItem) -> Send<Self> where
    Self: Sized, 

A future that completes after the given item has been fully processed into the sink, including flushing.

fn send_all<S>(self, stream: S) -> SendAll<Self, S> where
    S: Stream<Item = Self::SinkItem>,
    Self::SinkError: From<S::Error>,
    Self: Sized, 

A future that completes after the given stream has been fully processed into the sink, including flushing.

impl<S: Debug, F: Debug> Debug for MapErr<S, F>

fn fmt(&self, f: &mut Formatter) -> Result

Formats the value using the given formatter.