alloc/collections/vec_deque/
spec_from_iter.rs

1use super::{IntoIter, VecDeque};
2
3/// Specialization trait used for `VecDeque::from_iter`
4pub(super) trait SpecFromIter<T, I> {
5    fn spec_from_iter(iter: I) -> Self;
6}
7
8impl<T, I> SpecFromIter<T, I> for VecDeque<T>
9where
10    I: Iterator<Item = T>,
11{
12    #[track_caller]
13    default fn spec_from_iter(iterator: I) -> Self {
14        // Since converting is O(1) now, just re-use the `Vec` logic for
15        // anything where we can't do something extra-special for `VecDeque`,
16        // especially as that could save us some monomorphization work
17        // if one uses the same iterators (like slice ones) with both.
18        crate::vec::Vec::from_iter(iterator).into()
19    }
20}
21
22impl<T> SpecFromIter<T, crate::vec::IntoIter<T>> for VecDeque<T> {
23    #[inline]
24    fn spec_from_iter(iterator: crate::vec::IntoIter<T>) -> Self {
25        iterator.into_vecdeque()
26    }
27}
28
29impl<T> SpecFromIter<T, IntoIter<T>> for VecDeque<T> {
30    #[inline]
31    fn spec_from_iter(iterator: IntoIter<T>) -> Self {
32        iterator.into_vecdeque()
33    }
34}