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
128
|
#![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.
#[must_use = "this `Poll` may be a `Pending` variant, which should be handled"]
#[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> {
/// Changes 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 `true` if this is `Poll::Ready`
#[inline]
pub fn is_ready(&self) -> bool {
match *self {
Poll::Ready(_) => true,
Poll::Pending => false,
}
}
/// Returns `true` if this is `Poll::Pending`
#[inline]
pub fn is_pending(&self) -> bool {
!self.is_ready()
}
}
impl<T, E> Poll<Result<T, E>> {
/// Changes 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,
}
}
/// Changes 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))
}
}
|
