tinyvec/
arrayvec_drain.rs

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1use super::*;
2
3use core::{
4  ops::{Bound, RangeBounds},
5  slice,
6};
7
8/// Draining iterator for [`ArrayVec`]
9///
10/// See [`ArrayVec::drain`](ArrayVec::drain)
11pub struct ArrayVecDrain<'a, T: 'a + Default> {
12  iter: slice::IterMut<'a, T>,
13}
14
15impl<'a, T: 'a + Default> ArrayVecDrain<'a, T> {
16  pub(crate) fn new<A, R>(arr: &'a mut ArrayVec<A>, range: R) -> Self
17  where
18    A: Array<Item = T>,
19    R: RangeBounds<usize>,
20  {
21    let start = match range.start_bound() {
22      Bound::Unbounded => 0,
23      Bound::Included(&n) => n,
24      Bound::Excluded(&n) => n.saturating_add(1),
25    };
26    let end = match range.end_bound() {
27      Bound::Unbounded => arr.len(),
28      Bound::Included(&n) => n.saturating_add(1),
29      Bound::Excluded(&n) => n,
30    };
31
32    assert!(
33      start <= end,
34      "ArrayVec::drain> Illegal range, {} to {}",
35      start,
36      end
37    );
38    assert!(
39      end <= arr.len(),
40      "ArrayVec::drain> Range ends at {}, but length is only {}",
41      end,
42      arr.len()
43    );
44
45    let len = end - start;
46    let to_rotate = &mut arr[start..];
47    to_rotate.rotate_left(len);
48
49    let oldlen = arr.len();
50    let newlen = oldlen - len;
51    arr.set_len(newlen);
52    let slice = &mut arr.data.as_slice_mut()[newlen..oldlen];
53    let iter = slice.iter_mut();
54    Self { iter }
55  }
56}
57
58impl<'a, T: 'a + Default> DoubleEndedIterator for ArrayVecDrain<'a, T> {
59  fn next_back(&mut self) -> Option<Self::Item> {
60    self.iter.next_back().map(take)
61  }
62
63  #[cfg(feature = "rustc_1_40")]
64  fn nth_back(&mut self, n: usize) -> Option<Self::Item> {
65    self.iter.nth_back(n).map(take)
66  }
67}
68
69impl<'a, T: 'a + Default> Iterator for ArrayVecDrain<'a, T> {
70  type Item = T;
71  fn next(&mut self) -> Option<Self::Item> {
72    self.iter.next().map(take)
73  }
74  fn size_hint(&self) -> (usize, Option<usize>) {
75    self.iter.size_hint()
76  }
77  fn nth(&mut self, n: usize) -> Option<Self::Item> {
78    self.iter.nth(n).map(take)
79  }
80  fn last(self) -> Option<Self::Item> {
81    self.iter.last().map(take)
82  }
83  fn for_each<F>(self, f: F)
84  where
85    F: FnMut(Self::Item),
86  {
87    self.iter.map(take).for_each(f)
88  }
89}
90
91impl<'a, T: 'a + Default> FusedIterator for ArrayVecDrain<'a, T> {}
92impl<'a, T: 'a + Default> ExactSizeIterator for ArrayVecDrain<'a, T> {}
93/* No need to impl Drop! */
tinyvec/arrayvec_drain.rs

tinyvec/
arrayvec_drain.rs
