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

use crate::{
    fib::{Fiber, FiberRoot, FiberState},
    thr::prelude::*,
};
use core::{marker::Unpin, pin::Pin};

/// Fiber for [`FnMut`] closure.
///
/// Can be created with [`fib::new_fn`](crate::fib::new_fn).
pub struct FiberFn<F, Y, R>(Option<F>)
where
    F: FnMut() -> FiberState<Y, R>;

/// Fiber for [`FnOnce`] closure.
///
/// Can be created with [`fib::new_once`](crate::fib::new_once).
pub struct FiberOnce<F, R>(Option<F>)
where
    F: FnOnce() -> R,
    F: Unpin;

#[marker]
pub trait ReturnNone: Send + 'static {}

impl ReturnNone for () {}
impl ReturnNone for ! {}

impl<F, Y, R> Fiber for FiberFn<F, Y, R>
where
    F: FnMut() -> FiberState<Y, R>,
{
    type Input = ();
    type Yield = Y;
    type Return = R;

    fn resume(self: Pin<&mut Self>, (): ()) -> FiberState<Y, R> {
        let option = unsafe { &mut self.get_unchecked_mut().0 };
        match option {
            Some(f) => {
                let state = f();
                if state.is_complete() {
                    *option = None;
                }
                state
            }
            None => panic!("fiber resumed after completion"),
        }
    }
}

impl<F, R> FiberRoot for FiberFn<F, (), R>
where
    F: FnMut() -> FiberState<(), R>,
    F: Send + 'static,
    R: ReturnNone,
{
    #[inline]
    fn advance(self: Pin<&mut Self>) -> bool {
        match self.resume(()) {
            FiberState::Yielded(()) => true,
            FiberState::Complete(_) => false,
        }
    }
}

impl<F, R> Fiber for FiberOnce<F, R>
where
    F: FnOnce() -> R,
    F: Unpin,
{
    type Input = ();
    type Yield = !;
    type Return = R;

    fn resume(self: Pin<&mut Self>, (): ()) -> FiberState<!, R> {
        if let Some(f) = self.get_mut().0.take() {
            FiberState::Complete(f())
        } else {
            panic!("fiber resumed after completion");
        }
    }
}

impl<F> FiberRoot for FiberOnce<F, ()>
where
    F: FnOnce(),
    F: Unpin + Send + 'static,
{
    #[inline]
    fn advance(self: Pin<&mut Self>) -> bool {
        match self.resume(()) {
            FiberState::Complete(()) => false,
        }
    }
}

/// Creates a fiber from the closure `f`.
#[inline]
pub fn new_fn<F, Y, R>(f: F) -> FiberFn<F, Y, R>
where
    F: FnMut() -> FiberState<Y, R>,
{
    FiberFn(Some(f))
}

/// Creates a fiber from the closure `f`.
///
/// This type of fiber will never yield and will busy its thread until
/// completion.
#[inline]
pub fn new_once<F, R>(f: F) -> FiberOnce<F, R>
where
    F: FnOnce() -> R,
    F: Unpin,
{
    FiberOnce(Some(f))
}

/// Extends [`ThrToken`](crate::thr::ThrToken) types with `add_fn` and
/// `add_once` methods.
pub trait ThrFiberClosure: ThrToken {
    /// Adds a fiber for the closure `f` to the fiber chain.
    #[inline]
    fn add_fn<F, R>(self, f: F)
    where
        F: FnMut() -> FiberState<(), R>,
        F: Send + 'static,
        R: ReturnNone,
    {
        self.add_fib(new_fn(f))
    }

    /// Adds a fiber for the closure `f` to the fiber chain.
    #[inline]
    fn add_once<F>(self, f: F)
    where
        F: FnOnce(),
        F: Unpin + Send + 'static,
    {
        self.add_fib(new_once(f))
    }
}

impl<T: ThrToken> ThrFiberClosure for T {}