stack_dst 0.8.1

A wrapper that allows storage of unsized values of up to a fixed size inline (without boxing)
Documentation 
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extern crate stack_dst;

type DstFifo<T> = stack_dst::Fifo<T, ::stack_dst::buffers::Ptr8>;

#[test]
// A trivial check that ensures that methods are correctly called
fn trivial_type() {
    let mut val = DstFifo::<dyn PartialEq<u32>>::new();
    val.push_back_stable(1234, |p| p).unwrap();
    val.push_back_stable(1233, |p| p).unwrap();
    assert!(*val.front().unwrap() == 1234);
    assert!(*val.front().unwrap() != 1233);
    val.pop_front();
    assert!(*val.front().unwrap() != 1234);
    assert!(*val.front().unwrap() == 1233);
}

#[test]
fn slice_push_panic_safety() {
    use std::sync::atomic::{AtomicUsize, Ordering};
    static COUNT: AtomicUsize = AtomicUsize::new(0);
    struct Sentinel(bool);
    impl Clone for Sentinel {
        fn clone(&self) -> Self {
            if self.0 {
                panic!();
            } else {
                Sentinel(self.0)
            }
        }
    }
    impl Drop for Sentinel {
        fn drop(&mut self) {
            COUNT.fetch_add(1, Ordering::SeqCst);
        }
    }
    let input = [Sentinel(false), Sentinel(true)];

    let _ = ::std::panic::catch_unwind(::std::panic::AssertUnwindSafe(|| {
        let mut stack = DstFifo::<[Sentinel]>::new();
        let _ = stack.push_cloned(&input);
    }));
    assert_eq!(COUNT.load(Ordering::SeqCst), 1);
}

#[test]
fn retain() {
    use std::sync::atomic::{AtomicUsize, Ordering};
    static FLAGS: AtomicUsize = AtomicUsize::new(0);
    struct Sentinel(usize);
    impl ::std::ops::Drop for Sentinel {
        fn drop(&mut self) {
            let flag = 1 << self.0;
            let v = FLAGS.fetch_or(1 << self.0, Ordering::SeqCst);
            assert!(v & flag == 0);
        }
    }
    impl AsRef<Sentinel> for Sentinel {
        fn as_ref(&self) -> &Sentinel {
            self
        }
    }
    let mut stack: ::stack_dst::Fifo<dyn AsRef<Sentinel>, ::stack_dst::buffers::Ptr16> = ::stack_dst::Fifo::new();
    stack.push_back_stable(Sentinel(0), |v| v).ok().unwrap();
    stack.push_back_stable(Sentinel(1), |v| v).ok().unwrap();
    stack.push_back_stable(Sentinel(2), |v| v).ok().unwrap();
    stack.push_back_stable(Sentinel(3), |v| v).ok().unwrap();
    stack.push_back_stable(Sentinel(4), |v| v).ok().unwrap();

    stack.retain(|v| v.as_ref().0 > 2);
    assert_eq!(FLAGS.load(Ordering::SeqCst), 0b00_111);
    {
        let mut it = stack.iter().map(|v| v.as_ref().0);
        assert_eq!(it.next(), Some(3));
        assert_eq!(it.next(), Some(4));
        assert_eq!(it.next(), None);
    }
    drop(stack);
    assert_eq!(FLAGS.load(Ordering::SeqCst), 0b11_111);
}

#[cfg(not(feature="full_const_generics"))]
mod unaligned {
    use std::any::Any;
    use stack_dst::Fifo;
    type Buf8_16 = ::stack_dst::buffers::ArrayBuf<u8, ::stack_dst::buffers::n::U16>;
    #[test] #[should_panic]
    fn push_back_stable() {
        let mut stack = Fifo::<dyn Any, Buf8_16>::new();
        let _ = stack.push_back_stable(123u32, |v| v as _);
    }
    #[test] #[should_panic]
    #[cfg(feature = "unsize")]
    fn push_back() {
        let mut stack = Fifo::<dyn Any, Buf8_16>::new();
        let _ = stack.push_back(123u32);
    }

    #[test] #[should_panic]
    fn push_cloned() {
        let mut stack = Fifo::<[u32], Buf8_16>::new();
        let _ = stack.push_cloned(&[123u32]);
    }

    #[test] #[should_panic]
    fn push_copied() {
        let mut stack = Fifo::<[u32], Buf8_16>::new();
        let _ = stack.push_copied(&[123u32]);
    }
    #[test] #[should_panic]
    fn push_from_iter() {
        let mut stack = Fifo::<[u32], Buf8_16>::new();
        let _ = stack.push_from_iter(0..1);
    }
}