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Diffstat (limited to '')
-rw-r--r-- | library/alloc/src/collections/vec_deque/spec_from_iter.rs | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/library/alloc/src/collections/vec_deque/spec_from_iter.rs b/library/alloc/src/collections/vec_deque/spec_from_iter.rs new file mode 100644 index 000000000..7650492eb --- /dev/null +++ b/library/alloc/src/collections/vec_deque/spec_from_iter.rs @@ -0,0 +1,33 @@ +use super::{IntoIter, VecDeque}; + +/// Specialization trait used for `VecDeque::from_iter` +pub(super) trait SpecFromIter<T, I> { + fn spec_from_iter(iter: I) -> Self; +} + +impl<T, I> SpecFromIter<T, I> for VecDeque<T> +where + I: Iterator<Item = T>, +{ + default fn spec_from_iter(iterator: I) -> Self { + // Since converting is O(1) now, just re-use the `Vec` logic for + // anything where we can't do something extra-special for `VecDeque`, + // especially as that could save us some monomorphiziation work + // if one uses the same iterators (like slice ones) with both. + crate::vec::Vec::from_iter(iterator).into() + } +} + +impl<T> SpecFromIter<T, crate::vec::IntoIter<T>> for VecDeque<T> { + #[inline] + fn spec_from_iter(iterator: crate::vec::IntoIter<T>) -> Self { + iterator.into_vecdeque() + } +} + +impl<T> SpecFromIter<T, IntoIter<T>> for VecDeque<T> { + #[inline] + fn spec_from_iter(iterator: IntoIter<T>) -> Self { + iterator.into_vecdeque() + } +} |