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
22#[cfg(not(test))]
23impl<T> SpecFromIter<T, crate::vec::IntoIter<T>> for VecDeque<T> {
24 #[inline]
25 fn spec_from_iter(iterator: crate::vec::IntoIter<T>) -> Self {
26 iterator.into_vecdeque()
27 }
28}
29
30impl<T> SpecFromIter<T, IntoIter<T>> for VecDeque<T> {
31 #[inline]
32 fn spec_from_iter(iterator: IntoIter<T>) -> Self {
33 iterator.into_vecdeque()
34 }
35}
36