asynciter 0.1.0

Asynchronous iterator.
Documentation 
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use crate::AsyncIterator;

#[derive(Clone, Debug)]
#[must_use = "iterators are lazy and do nothing unless consumed"]
pub struct Take<I> {
    iter: I,
    n: usize,
}

impl<I> Take<I> {
    pub fn new(iter: I, n: usize) -> Take<I> {
        Take { iter, n }
    }
}

impl<I: AsyncIterator> AsyncIterator for Take<I> {
    type Item = I::Item;

    #[inline]
    async fn next(&mut self) -> Option<I::Item> {
        if self.n != 0 {
            self.n -= 1;
            self.iter.next().await
        } else {
            None
        }
    }

    #[inline]
    fn size_hint(&self) -> (usize, Option<usize>) {
        if self.n == 0 {
            return (0, Some(0));
        }

        let (lower, upper) = self.iter.size_hint();

        let lower = std::cmp::min(lower, self.n);

        let upper = match upper {
            Some(x) if x < self.n => Some(x),
            _ => Some(self.n),
        };

        (lower, upper)
    }
}