      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
     81
     82
     83
     84
     85
     86
     87
     88
     89
     90
     91
     92
     93
     94
     95
     96
     97
     98
     99
    100
    101
    102
    103
    104
    105
    106
    107
    108
    109
    110
    111
    112
    113
    114
    115
    116
    117
    118
    119
    120
    121
    122
    123
    124
    125
    126
    127

    #![unstable(feature = "futures_api",
                reason = "futures in libcore are unstable",
                issue = "50547")]

    use ops::Try;
    use result::Result;

    /// Indicates whether a value is available or if the current task has been
    /// scheduled to receive a wakeup instead.
    #[derive(Copy, Clone, Debug, Eq, PartialEq, Ord, PartialOrd, Hash)]
    pub enum Poll<T> {
        /// Represents that a value is immediately ready.
        Ready(T),

        /// Represents that a value is not ready yet.
        ///
        /// When a function returns `Pending`, the function *must* also
        /// ensure that the current task is scheduled to be awoken when
        /// progress can be made.
        Pending,
    }

    impl<T> Poll<T> {
        /// Change the ready value of this `Poll` with the closure provided
        pub fn map<U, F>(self, f: F) -> Poll<U>
            where F: FnOnce(T) -> U
        {
            match self {
                Poll::Ready(t) => Poll::Ready(f(t)),
                Poll::Pending => Poll::Pending,
            }
        }

        /// Returns whether this is `Poll::Ready`
        #[inline]
        pub fn is_ready(&self) -> bool {
            match *self {
                Poll::Ready(_) => true,
                Poll::Pending => false,
            }
        }

        /// Returns whether this is `Poll::Pending`
        #[inline]
        pub fn is_pending(&self) -> bool {
            !self.is_ready()
        }
    }

    impl<T, E> Poll<Result<T, E>> {
        /// Change the success value of this `Poll` with the closure provided
        pub fn map_ok<U, F>(self, f: F) -> Poll<Result<U, E>>
            where F: FnOnce(T) -> U
        {
            match self {
                Poll::Ready(Ok(t)) => Poll::Ready(Ok(f(t))),
                Poll::Ready(Err(e)) => Poll::Ready(Err(e)),
                Poll::Pending => Poll::Pending,
            }
        }

        /// Change the error value of this `Poll` with the closure provided
        pub fn map_err<U, F>(self, f: F) -> Poll<Result<T, U>>
            where F: FnOnce(E) -> U
        {
            match self {
                Poll::Ready(Ok(t)) => Poll::Ready(Ok(t)),
                Poll::Ready(Err(e)) => Poll::Ready(Err(f(e))),
                Poll::Pending => Poll::Pending,
            }
        }
    }

    impl<T> From<T> for Poll<T> {
        fn from(t: T) -> Poll<T> {
            Poll::Ready(t)
        }
    }

    impl<T, E> Try for Poll<Result<T, E>> {
        type Ok = Poll<T>;
        type Error = E;

        #[inline]
        fn into_result(self) -> Result<Self::Ok, Self::Error> {
            match self {
                Poll::Ready(Ok(x)) => Ok(Poll::Ready(x)),
                Poll::Ready(Err(e)) => Err(e),
                Poll::Pending => Ok(Poll::Pending),
            }
        }

        #[inline]
        fn from_error(e: Self::Error) -> Self {
            Poll::Ready(Err(e))
        }

        #[inline]
        fn from_ok(x: Self::Ok) -> Self {
            x.map(Ok)
        }
    }

    impl<T, E> Try for Poll<Option<Result<T, E>>> {
        type Ok = Poll<Option<T>>;
        type Error = E;

        #[inline]
        fn into_result(self) -> Result<Self::Ok, Self::Error> {
            match self {
                Poll::Ready(Some(Ok(x))) => Ok(Poll::Ready(Some(x))),
                Poll::Ready(Some(Err(e))) => Err(e),
                Poll::Ready(None) => Ok(Poll::Ready(None)),
                Poll::Pending => Ok(Poll::Pending),
            }
        }

        #[inline]
        fn from_error(e: Self::Error) -> Self {
            Poll::Ready(Some(Err(e)))
        }

        #[inline]
        fn from_ok(x: Self::Ok) -> Self {
            x.map(|x| x.map(Ok))
        }
    }

# 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`)

Search multiple things at once by splitting your query with comma (e.g., `str,u8` or `String,struct:Vec,test`)