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use super::*;
use core::{
ops::{Bound, RangeBounds},
slice,
};
/// Draining iterator for [`ArrayVec`]
///
/// See [`ArrayVec::drain`](ArrayVec::drain)
pub struct ArrayVecDrain<'a, T: 'a + Default> {
iter: slice::IterMut<'a, T>,
}
impl<'a, T: 'a + Default> ArrayVecDrain<'a, T> {
pub(crate) fn new<A, R>(arr: &'a mut ArrayVec<A>, range: R) -> Self
where
A: Array<Item = T>,
R: RangeBounds<usize>,
{
let start = match range.start_bound() {
Bound::Unbounded => 0,
Bound::Included(&n) => n,
Bound::Excluded(&n) => n.saturating_add(1),
};
let end = match range.end_bound() {
Bound::Unbounded => arr.len(),
Bound::Included(&n) => n.saturating_add(1),
Bound::Excluded(&n) => n,
};
assert!(
start <= end,
"ArrayVec::drain> Illegal range, {} to {}",
start,
end
);
assert!(
end <= arr.len(),
"ArrayVec::drain> Range ends at {}, but length is only {}",
end,
arr.len()
);
let len = end - start;
let to_rotate = &mut arr[start..];
to_rotate.rotate_left(len);
let oldlen = arr.len();
let newlen = oldlen - len;
arr.set_len(newlen);
let slice = &mut arr.data.as_slice_mut()[newlen..oldlen];
let iter = slice.iter_mut();
Self { iter }
}
}
impl<'a, T: 'a + Default> DoubleEndedIterator for ArrayVecDrain<'a, T> {
fn next_back(&mut self) -> Option<Self::Item> {
self.iter.next_back().map(take)
}
#[cfg(feature = "rustc_1_40")]
fn nth_back(&mut self, n: usize) -> Option<Self::Item> {
self.iter.nth_back(n).map(take)
}
}
impl<'a, T: 'a + Default> Iterator for ArrayVecDrain<'a, T> {
type Item = T;
fn next(&mut self) -> Option<Self::Item> {
self.iter.next().map(take)
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.iter.size_hint()
}
fn nth(&mut self, n: usize) -> Option<Self::Item> {
self.iter.nth(n).map(take)
}
fn last(self) -> Option<Self::Item> {
self.iter.last().map(take)
}
fn for_each<F>(self, f: F)
where
F: FnMut(Self::Item),
{
self.iter.map(take).for_each(f)
}
}
impl<'a, T: 'a + Default> FusedIterator for ArrayVecDrain<'a, T> {}
impl<'a, T: 'a + Default> ExactSizeIterator for ArrayVecDrain<'a, T> {}
/* No need to impl Drop! */
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