finchers_core/
poll.rs

1use futures::{self, Async};
2#[cfg(feature = "nightly")]
3use std::ops::Try;
4
5/// A type alias of `Poll<Result<T, E>>`.
6pub type PollResult<T, E> = Poll<Result<T, E>>;
7
8/// An enum which indicates whether a value is ready or not.
9// FIXME: replace with core::task::Poll
10#[derive(Debug, Copy, Clone, PartialEq)]
11pub enum Poll<T> {
12    /// The task has just been finished with a returned value of `T`.
13    Ready(T),
14
15    /// The task is not ready and should be scheduled to be awoken by the executor.
16    Pending,
17}
18
19impl<T> Poll<T> {
20    /// Return whether the value is `Pending`.
21    pub fn is_pending(&self) -> bool {
22        match *self {
23            Poll::Pending => true,
24            _ => false,
25        }
26    }
27
28    /// Return whether the value is `Ready`.
29    pub fn is_ready(&self) -> bool {
30        !self.is_pending()
31    }
32
33    /// Maps the value to a new type with given function.
34    pub fn map<F, U>(self, f: F) -> Poll<U>
35    where
36        F: FnOnce(T) -> U,
37    {
38        match self {
39            Poll::Pending => Poll::Pending,
40            Poll::Ready(t) => Poll::Ready(f(t)),
41        }
42    }
43}
44
45impl<T, E> Poll<Result<T, E>> {
46    /// Return whether the value is `Ready(Ok(t))`.
47    pub fn is_ok(&self) -> bool {
48        match *self {
49            Poll::Ready(Ok(..)) => true,
50            _ => false,
51        }
52    }
53
54    /// Return whether the value is `Ready(Err(t))`.
55    pub fn is_err(&self) -> bool {
56        match *self {
57            Poll::Ready(Err(..)) => true,
58            _ => false,
59        }
60    }
61
62    /// Maps the value to a new type with given function if the value is `Ok`.
63    pub fn map_ok<F, U>(self, f: F) -> Poll<Result<U, E>>
64    where
65        F: FnOnce(T) -> U,
66    {
67        self.map(|t| t.map(f))
68    }
69
70    /// Maps the value to a new type with given function if the value is `Err`.
71    pub fn map_err<F, U>(self, f: F) -> Poll<Result<T, U>>
72    where
73        F: FnOnce(E) -> U,
74    {
75        self.map(|t| t.map_err(f))
76    }
77}
78
79impl<T> From<T> for Poll<T> {
80    fn from(ready: T) -> Poll<T> {
81        Poll::Ready(ready)
82    }
83}
84
85impl<T> From<Async<T>> for Poll<T> {
86    fn from(v: Async<T>) -> Self {
87        match v {
88            Async::NotReady => Poll::Pending,
89            Async::Ready(v) => Poll::Ready(v),
90        }
91    }
92}
93
94impl<T> Into<Async<T>> for Poll<T> {
95    fn into(self) -> Async<T> {
96        match self {
97            Poll::Pending => Async::NotReady,
98            Poll::Ready(v) => Async::Ready(v),
99        }
100    }
101}
102
103impl<T, E> From<futures::Poll<T, E>> for Poll<Result<T, E>> {
104    fn from(v: futures::Poll<T, E>) -> Self {
105        match v {
106            Ok(Async::NotReady) => Poll::Pending,
107            Ok(Async::Ready(ok)) => Poll::Ready(Ok(ok)),
108            Err(err) => Poll::Ready(Err(err)),
109        }
110    }
111}
112
113impl<T, E> Into<futures::Poll<T, E>> for Poll<Result<T, E>> {
114    fn into(self) -> futures::Poll<T, E> {
115        match self {
116            Poll::Pending => Ok(Async::NotReady),
117            Poll::Ready(Ok(ok)) => Ok(Async::Ready(ok)),
118            Poll::Ready(Err(err)) => Err(err),
119        }
120    }
121}
122
123#[cfg(feature = "nightly")]
124impl<T, E> Try for Poll<Result<T, E>> {
125    type Ok = T;
126    type Error = PollError<E>;
127
128    fn into_result(self) -> Result<Self::Ok, Self::Error> {
129        match self {
130            Poll::Pending => Err(PollError::Pending),
131            Poll::Ready(Ok(ok)) => Ok(ok),
132            Poll::Ready(Err(e)) => Err(PollError::Error(e)),
133        }
134    }
135
136    fn from_ok(v: Self::Ok) -> Self {
137        Poll::Ready(Ok(v))
138    }
139
140    fn from_error(v: Self::Error) -> Self {
141        match v {
142            PollError::Pending => Poll::Pending,
143            PollError::Error(err) => Poll::Ready(Err(err)),
144        }
145    }
146}
147
148// An opaque type for implementation of Try
149#[cfg(feature = "nightly")]
150#[allow(missing_docs)]
151#[allow(missing_debug_implementations)]
152pub enum PollError<E> {
153    Pending,
154    Error(E),
155}
156
157/// A helper macro for extracting the value of `Poll<T>`.
158#[macro_export]
159macro_rules! poll {
160    ($e:expr) => {{
161        use $crate::Poll;
162        match Poll::from($e) {
163            Poll::Ready(v) => v,
164            Poll::Pending => return Poll::Pending,
165        }
166    }};
167}
168
169/// A helper macro for extracting the successful value of `PollResult<T, E>`.
170#[macro_export]
171macro_rules! poll_result {
172    ($e:expr) => {{
173        use $crate::Poll;
174        match Poll::from($e) {
175            Poll::Ready(Ok(v)) => v,
176            Poll::Ready(Err(e)) => return Poll::Ready(Err(Into::into(e))),
177            Poll::Pending => return Poll::Pending,
178        }
179    }};
180}
finchers_core/poll.rs

finchers_core/
poll.rs
