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
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163

use crate::reactor::*;
use derive_more::{Deref, DerefMut};
use futures::executor::block_on;
use futures::sink::{Sink, SinkExt};
use futures::task::{Context, Poll};
use pin_project::*;
use std::{borrow::ToOwned, pin::Pin};

/// An adapter for types that implement [`Sink`] to behave as a [`Reactor`] (requires [`async`])
///
/// Returned by [`Reactor::from_sink`].
///
/// [`async`]: index.html#optional-features
/// [`Reactor::from_sink`]: trait.Reactor.html#method.from_sink
#[pin_project]
#[derive(Debug, Default, Copy, Clone, Eq, PartialEq, Hash, Deref, DerefMut)]
pub struct AsyncReactor<T, F> {
    #[pin]
    #[deref]
    #[deref_mut]
    sink: T,
    with: F,
}

impl<S, T, F, E> Reactor<S> for AsyncReactor<T, F>
where
    S: ?Sized,
    Self: for<'s> Sink<&'s S, Error = E> + Unpin,
{
    /// The reason why the state couldn't be sent through the sink.
    type Error = E;

    /// Sends an owned version of the state through the sink.
    fn react(&mut self, state: &S) -> Result<(), Self::Error> {
        block_on(self.send(state))
    }
}

impl<S, T, F, O> Sink<&S> for AsyncReactor<T, F>
where
    S: ?Sized,
    T: Sink<O>,
    F: for<'s> Fn(&'s S) -> O,
{
    type Error = T::Error;

    fn poll_ready(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
        self.project().sink.poll_ready(cx)
    }

    #[project]
    fn start_send(self: Pin<&mut Self>, state: &S) -> Result<(), Self::Error> {
        #[project]
        let AsyncReactor { sink, with } = self.project();
        sink.start_send(with(state))
    }

    fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
        self.project().sink.poll_flush(cx)
    }

    fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
        self.project().sink.poll_close(cx)
    }
}

impl<S, E> dyn Reactor<S, Error = E>
where
    S: ?Sized,
{
    /// Adapts any type that implements [`Sink`] as a [`Reactor`] (requires [`async`]).
    ///
    /// This function is equivalent to
    /// [`Reactor::<S, Error = E>::from_sink_with(sink, S::to_owned)`][from_sink_with].
    ///
    /// [`async`]: index.html#optional-features
    /// [from_sink_with]: trait.Reactor.html#method.from_sink_with
    pub fn from_sink<T>(sink: T) -> AsyncReactor<T, fn(&S) -> S::Owned>
    where
        S: ToOwned,
        T: Sink<S::Owned, Error = E> + Unpin,
    {
        Reactor::<S, Error = E>::from_sink_with(sink, S::to_owned)
    }

    /// Adapts any type that implements [`Sink`] as a [`Reactor`] (requires [`async`]).
    ///
    /// [`async`]: index.html#optional-features
    ///
    /// # Example
    /// ```rust
    /// use reducer::*;
    /// use futures::channel::mpsc::channel;
    /// use futures::executor::block_on_stream;
    /// use std::{thread, string::ToString};
    ///
    /// let (tx, rx) = channel(0);
    /// let mut reactor = Reactor::<_, Error = _>::from_sink_with(tx, ToString::to_string);
    ///
    /// thread::spawn(move || {
    ///     reactor.react(&1);
    ///     reactor.react(&1);
    ///     reactor.react(&2);
    ///     reactor.react(&3);
    ///     reactor.react(&5);
    ///     reactor.react(&8);
    /// });
    ///
    /// assert_eq!(block_on_stream(rx).collect::<String>(), "112358".to_string());
    /// ```
    pub fn from_sink_with<T, F, O>(sink: T, with: F) -> AsyncReactor<T, F>
    where
        T: Sink<O, Error = E> + Unpin,
        F: for<'s> Fn(&'s S) -> O,
    {
        AsyncReactor { sink, with }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use mockall::predicate::*;
    use proptest::prelude::*;
    use std::{ops::*, string::String};

    #[test]
    fn deref() {
        let mut reactor = Reactor::<(), Error = ()>::from_sink(MockReactor::new());

        assert_eq!(reactor.deref() as *const _, &reactor.sink as *const _);
        assert_eq!(reactor.deref_mut() as *mut _, &mut reactor.sink as *mut _);
    }

    proptest! {
        #[test]
        fn react(state: String, result: Result<(), u8>) {
            let mut mock = MockReactor::new();

            mock.expect_react()
                .with(eq(state.clone()))
                .times(1)
                .return_const(result);

            let mut reactor = Reactor::<str, Error = _>::from_sink(mock);
            assert_eq!(Reactor::react(&mut reactor, &state), result);
        }

        #[test]
        fn sink(state: String, result: Result<(), u8>) {
            let mut mock = MockReactor::new();

            mock.expect_react()
                .with(eq(state.clone()))
                .times(1)
                .return_const(result);

            let mut reactor = Reactor::<str, Error = _>::from_sink(mock);
            assert_eq!(block_on(reactor.send(&state)), result);
            assert_eq!(block_on(reactor.close()), Ok(()));
        }
    }
}