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Simplify binary_heap::PeekMut struct and destructor #76334

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Simplify binary_heap::PeekMut struct and destructor #76334

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15 changes: 6 additions & 9 deletions library/alloc/src/collections/binary_heap.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -260,7 +260,6 @@ pub struct BinaryHeap<T> {
#[stable(feature = "binary_heap_peek_mut", since = "1.12.0")]
pub struct PeekMut<'a, T: 'a + Ord> {
heap: &'a mut BinaryHeap<T>,
sift: bool,
}

#[stable(feature = "collection_debug", since = "1.17.0")]
Expand All @@ -273,9 +272,7 @@ impl<T: Ord + fmt::Debug> fmt::Debug for PeekMut<'_, T> {
#[stable(feature = "binary_heap_peek_mut", since = "1.12.0")]
impl<T: Ord> Drop for PeekMut<'_, T> {
fn drop(&mut self) {
if self.sift {
self.heap.sift_down(0);
}
self.heap.sift_down(0);
}
}

Expand All @@ -301,10 +298,10 @@ impl<T: Ord> DerefMut for PeekMut<'_, T> {
impl<'a, T: Ord> PeekMut<'a, T> {
/// Removes the peeked value from the heap and returns it.
#[stable(feature = "binary_heap_peek_mut_pop", since = "1.18.0")]
pub fn pop(mut this: PeekMut<'a, T>) -> T {
let value = this.heap.pop().unwrap();
this.sift = false;
value
pub fn pop(this: PeekMut<'a, T>) -> T {
// Destructor is unnecessary since pop() already sifts heap
let mut this = ManuallyDrop::new(this);
this.heap.pop().unwrap()
}
}

Expand Down Expand Up @@ -401,7 +398,7 @@ impl<T: Ord> BinaryHeap<T> {
/// Cost is *O*(1) in the worst case.
#[stable(feature = "binary_heap_peek_mut", since = "1.12.0")]
pub fn peek_mut(&mut self) -> Option<PeekMut<'_, T>> {
if self.is_empty() { None } else { Some(PeekMut { heap: self, sift: true }) }
if self.is_empty() { None } else { Some(PeekMut { heap: self }) }
}

/// Removes the greatest item from the binary heap and returns it, or `None` if it
Expand Down