diff options
| -rw-r--r-- | library/alloc/src/collections/vec_deque/mod.rs | 17 |
1 files changed, 12 insertions, 5 deletions
diff --git a/library/alloc/src/collections/vec_deque/mod.rs b/library/alloc/src/collections/vec_deque/mod.rs index 86d77182bcc..a477bab068b 100644 --- a/library/alloc/src/collections/vec_deque/mod.rs +++ b/library/alloc/src/collections/vec_deque/mod.rs @@ -2700,12 +2700,18 @@ impl<T, A: Allocator> IndexMut<usize> for VecDeque<T, A> { #[stable(feature = "rust1", since = "1.0.0")] impl<T> FromIterator<T> for VecDeque<T> { + #[inline] fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> VecDeque<T> { - let iterator = iter.into_iter(); - let (lower, _) = iterator.size_hint(); - let mut deq = VecDeque::with_capacity(lower); - deq.extend(iterator); - deq + // Since converting is O(1) now, might as well re-use that logic + // (including things like the `vec::IntoIter`→`Vec` specialization) + // especially as that could save us some monomorphiziation work + // if one uses the same iterators (like slice ones) with both. + return from_iter_via_vec(iter.into_iter()); + + #[inline] + fn from_iter_via_vec<U>(iter: impl Iterator<Item = U>) -> VecDeque<U> { + Vec::from_iter(iter).into() + } } } @@ -2792,6 +2798,7 @@ impl<T, A: Allocator> From<Vec<T, A>> for VecDeque<T, A> { /// In its current implementation, this is a very cheap /// conversion. This isn't yet a guarantee though, and /// shouldn't be relied on. + #[inline] fn from(other: Vec<T, A>) -> Self { let (ptr, len, cap, alloc) = other.into_raw_parts_with_alloc(); Self { head: 0, len, buf: unsafe { RawVec::from_raw_parts_in(ptr, cap, alloc) } } |