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    use std::sync::atomic::{AtomicPtr, Ordering};
    use std::ptr;

    unsafe impl<T: Send> Send for AtomicOption<T> {}
    unsafe impl<T: Send> Sync for AtomicOption<T> {}

    #[derive(Debug)]
    pub struct AtomicOption<T> {
        inner: AtomicPtr<T>,
    }

    impl<T> Drop for AtomicOption<T> {
        fn drop(&mut self) {
            let inner = self.inner.load(Ordering::Relaxed);
            if !inner.is_null() {
                unsafe {
                    drop(Box::from_raw(inner));
                }
            }
        }
    }

    impl<T> AtomicOption<T> {
        pub fn new() -> AtomicOption<T> {
            AtomicOption { inner: AtomicPtr::new(ptr::null_mut()) }
        }

        fn swap_inner(&self, ptr: *mut T, order: Ordering) -> Option<Box<T>> {
            let old = self.inner.swap(ptr, order);
            if old.is_null() {
                None
            } else {
                Some(unsafe { Box::from_raw(old) })
            }
        }

        // allows re-use of allocation
        pub fn swap_box(&self, t: Box<T>, order: Ordering) -> Option<Box<T>> {
            self.swap_inner(Box::into_raw(t), order)
        }

        pub fn swap(&self, t: T, order: Ordering) -> Option<T> {
            self.swap_box(Box::new(t), order).map(|old| *old)
        }

        pub fn take(&self, order: Ordering) -> Option<T> {
            self.swap_inner(ptr::null_mut(), order).map(|old| *old)
        }
    }

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