pub enum Either<A, B> {
    Left(A),
    Right(B),
}
Expand description

Combines two different futures, streams, or sinks having the same associated types into a single type.

This is useful when conditionally choosing between two distinct future types:

use futures::future::Either;

let cond = true;

let fut = if cond {
    Either::Left(async move { 12 })
} else {
    Either::Right(async move { 44 })
};

assert_eq!(fut.await, 12);

Variants§

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Left(A)

First branch of the type

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Right(B)

Second branch of the type

Implementations§

Convert Pin<&Either<A, B>> to Either<Pin<&A>, Pin<&B>>, pinned projections of the inner variants.

Convert Pin<&mut Either<A, B>> to Either<Pin<&mut A>, Pin<&mut B>>, pinned projections of the inner variants.

Factor out a homogeneous type from an either of pairs.

Here, the homogeneous type is the first element of the pairs.

Factor out a homogeneous type from an either of pairs.

Here, the homogeneous type is the second element of the pairs.

Extract the value of an either over two equivalent types.

Trait Implementations§

Attempt to return the contents of the internal buffer, filling it with more data from the inner reader if it is empty. Read more
Tells this buffer that amt bytes have been consumed from the buffer, so they should no longer be returned in calls to poll_read. Read more
Attempt to read from the AsyncRead into buf. Read more
Attempt to read from the AsyncRead into bufs using vectored IO operations. Read more
Attempt to seek to an offset, in bytes, in a stream. Read more
Attempt to write bytes from buf into the object. Read more
Attempt to write bytes from bufs into the object using vectored IO operations. Read more
Attempt to flush the object, ensuring that any buffered data reach their destination. Read more
Attempt to close the object. Read more
Returns a copy of the value. Read more
Performs copy-assignment from source. Read more
Formats the value using the given formatter. Read more
Returns true if the underlying future should no longer be polled.
Returns true if the stream should no longer be polled.
The type of value produced on completion.
Attempt to resolve the future to a final value, registering the current task for wakeup if the value is not yet available. Read more
The type of value produced by the sink when an error occurs.
Attempts to prepare the Sink to receive a value. Read more
Begin the process of sending a value to the sink. Each call to this function must be preceded by a successful call to poll_ready which returned Poll::Ready(Ok(())). Read more
Flush any remaining output from this sink. Read more
Flush any remaining output and close this sink, if necessary. Read more
Values yielded by the stream.
Attempt to pull out the next value of this stream, registering the current task for wakeup if the value is not yet available, and returning None if the stream is exhausted. Read more
Returns the bounds on the remaining length of the stream. Read more

Auto Trait Implementations§

Blanket Implementations§

Gets the TypeId of self. Read more
Creates a future which will wait for a non-empty buffer to be available from this I/O object or EOF to be reached. Read more
A convenience for calling AsyncBufRead::consume on Unpin IO types. Read more
Creates a future which will read all the bytes associated with this I/O object into buf until the delimiter byte or EOF is reached. This method is the async equivalent to BufRead::read_until. Read more
Creates a future which will read all the bytes associated with this I/O object into buf until a newline (the 0xA byte) or EOF is reached, This method is the async equivalent to BufRead::read_line. Read more
Returns a stream over the lines of this reader. This method is the async equivalent to BufRead::lines. Read more
Creates an adaptor which will chain this stream with another. Read more
Tries to read some bytes directly into the given buf in asynchronous manner, returning a future type. Read more
Creates a future which will read from the AsyncRead into bufs using vectored IO operations. Read more
Creates a future which will read exactly enough bytes to fill buf, returning an error if end of file (EOF) is hit sooner. Read more
Creates a future which will read all the bytes from this AsyncRead. Read more
Creates a future which will read all the bytes from this AsyncRead. Read more
Helper method for splitting this read/write object into two halves. Read more
Creates an AsyncRead adapter which will read at most limit bytes from the underlying reader. Read more
Creates a future which will seek an IO object, and then yield the new position in the object and the object itself. Read more
Creates a future which will return the current seek position from the start of the stream. Read more
Creates a future which will entirely flush this AsyncWrite. Read more
Creates a future which will entirely close this AsyncWrite.
Creates a future which will write bytes from buf into the object. Read more
Creates a future which will write bytes from bufs into the object using vectored IO operations. Read more
Write data into this object. Read more
Allow using an AsyncWrite as a Sink<Item: AsRef<[u8]>>. Read more
Immutably borrows from an owned value. Read more
Mutably borrows from an owned value. Read more

Returns the argument unchanged.

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

The output that the future will produce on completion.
Which kind of future are we turning this into?
Creates a future from a value. Read more
Composes a function in front of the sink. Read more
Composes a function in front of the sink. Read more
Transforms the error returned by the sink.
Map this sink’s error to a different error type using the Into trait. Read more
Adds a fixed-size buffer to the current sink. Read more
Close the sink.
Fanout items to multiple sinks. Read more
Flush the sink, processing all pending items. Read more
A future that completes after the given item has been fully processed into the sink, including flushing. Read more
A future that completes after the given item has been received by the sink. Read more
A future that completes after the given stream has been fully processed into the sink, including flushing. Read more
Wrap this sink in an Either sink, making it the left-hand variant of that Either. Read more
Wrap this stream in an Either stream, making it the right-hand variant of that Either. Read more
A convenience method for calling Sink::poll_ready on Unpin sink types.
A convenience method for calling Sink::start_send on Unpin sink types.
A convenience method for calling Sink::poll_flush on Unpin sink types.
A convenience method for calling Sink::poll_close on Unpin sink types.
The resulting type after obtaining ownership.
Creates owned data from borrowed data, usually by cloning. Read more
Uses borrowed data to replace owned data, usually by cloning. Read more
The type returned in the event of a conversion error.
Performs the conversion.
The type of successful values yielded by this future
The type of failures yielded by this future
Poll this TryFuture as if it were a Future. Read more
The type returned in the event of a conversion error.
Performs the conversion.
The type of successful values yielded by this future
The type of failures yielded by this future
Poll this TryStream as if it were a Stream. Read more