``` 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
```
```//! Definition of the `Result` (immediately finished) combinator

use core::result;

use {Future, Poll, Async};

/// A future representing a value that is immediately ready.
///
/// Created by the `result` function.
#[derive(Debug, Clone)]
#[must_use = "futures do nothing unless polled"]
// TODO: rename this to `Result` on the next major version
pub struct FutureResult<T, E> {
inner: Option<result::Result<T, E>>,
}

/// Creates a new "leaf future" which will resolve with the given result.
///
/// The returned future represents a computation which is finished immediately.
/// This can be useful with the `finished` and `failed` base future types to
/// convert an immediate value to a future to interoperate elsewhere.
///
/// # Examples
///
/// ```
/// use futures::future::*;
///
/// let future_of_1 = result::<u32, u32>(Ok(1));
/// let future_of_err_2 = result::<u32, u32>(Err(2));
/// ```
pub fn result<T, E>(r: result::Result<T, E>) -> FutureResult<T, E> {
FutureResult { inner: Some(r) }
}

/// Creates a "leaf future" from an immediate value of a finished and
/// successful computation.
///
/// The returned future is similar to `result` where it will immediately run a
/// scheduled callback with the provided value.
///
/// # Examples
///
/// ```
/// use futures::future::*;
///
/// let future_of_1 = ok::<u32, u32>(1);
/// ```
pub fn ok<T, E>(t: T) -> FutureResult<T, E> {
result(Ok(t))
}

/// Creates a "leaf future" from an immediate value of a failed computation.
///
/// The returned future is similar to `result` where it will immediately run a
/// scheduled callback with the provided value.
///
/// # Examples
///
/// ```
/// use futures::future::*;
///
/// let future_of_err_1 = err::<u32, u32>(1);
/// ```
pub fn err<T, E>(e: E) -> FutureResult<T, E> {
result(Err(e))
}

impl<T, E> Future for FutureResult<T, E> {
type Item = T;
type Error = E;

fn poll(&mut self) -> Poll<T, E> {