# or_else.rs.html -- source
Source to the Rust file `/Users/travis/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-0.1.20/src/stream/or_else.rs`.
Keywords: rust, rustlang, rust-lang

     1
     2
     3
     4
     5
     6
     7
     8
     9
    10
    11
    12
    13
    14
    15
    16
    17
    18
    19
    20
    21
    22
    23
    24
    25
    26
    27
    28
    29
    30
    31
    32
    33
    34
    35
    36
    37
    38
    39
    40
    41
    42
    43
    44
    45
    46
    47
    48
    49
    50
    51
    52
    53
    54
    55
    56
    57
    58
    59
    60
    61
    62
    63
    64
    65
    66
    67
    68
    69
    70
    71
    72
    73
    74
    75
    76
    77
    78
    79
    80

    use {IntoFuture, Future, Poll, Async};
    use stream::Stream;

    /// A stream combinator which chains a computation onto errors produced by a
    /// stream.
    ///
    /// This structure is produced by the `Stream::or_else` method.
    #[derive(Debug)]
    #[must_use = "streams do nothing unless polled"]
    pub struct OrElse<S, F, U>
        where U: IntoFuture,
    {
        stream: S,
        future: Option<U::Future>,
        f: F,
    }

    pub fn new<S, F, U>(s: S, f: F) -> OrElse<S, F, U>
        where S: Stream,
              F: FnMut(S::Error) -> U,
              U: IntoFuture<Item=S::Item>,
    {
        OrElse {
            stream: s,
            future: None,
            f: f,
        }
    }

    // Forwarding impl of Sink from the underlying stream
    impl<S, F, U> ::sink::Sink for OrElse<S, F, U>
        where S: ::sink::Sink, U: IntoFuture
    {
        type SinkItem = S::SinkItem;
        type SinkError = S::SinkError;

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

        fn poll_complete(&mut self) -> Poll<(), S::SinkError> {
            self.stream.poll_complete()
        }

        fn close(&mut self) -> Poll<(), S::SinkError> {
            self.stream.close()
        }
    }

    impl<S, F, U> Stream for OrElse<S, F, U>
        where S: Stream,
              F: FnMut(S::Error) -> U,
              U: IntoFuture<Item=S::Item>,
    {
        type Item = S::Item;
        type Error = U::Error;

        fn poll(&mut self) -> Poll<Option<S::Item>, U::Error> {
            if self.future.is_none() {
                let item = match self.stream.poll() {
                    Ok(Async::Ready(e)) => return Ok(Async::Ready(e)),
                    Ok(Async::NotReady) => return Ok(Async::NotReady),
                    Err(e) => e,
                };
                self.future = Some((self.f)(item).into_future());
            }
            assert!(self.future.is_some());
            match self.future.as_mut().unwrap().poll() {
                Ok(Async::Ready(e)) => {
                    self.future = None;
                    Ok(Async::Ready(Some(e)))
                }
                Err(e) => {
                    self.future = None;
                    Err(e)
                }
                Ok(Async::NotReady) => Ok(Async::NotReady)
            }
        }
    }

# Help

## Keyboard Shortcuts

`?`
  Show this help dialog
`S`
  Focus the search field
`↑`
  Move up in search results
`↓`
  Move down in search results
`↹`
  Switch tab
`⏎`
  Go to active search result
`+`
  Expand all sections
`-`
  Collapse all sections

## Search Tricks

Prefix searches with a type followed by a colon (e.g. `fn:`) to restrict the search to a given type.

Accepted types are: `fn`, `mod`, `struct`, `enum`, `trait`, `type`, `macro`, and `const`.

Search functions by type signature (e.g. `vec -> usize` or `* -> vec`)