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The scope of the unsafe block can be appropriately reduced #32

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The scope of the unsafe block can be appropriately reduced #32

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28 changes: 14 additions & 14 deletions src/binary_heap.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -942,8 +942,8 @@ impl<T, C: Compare<T>> BinaryHeap<T, C> {
// so it's always a valid index to access.
// It is safe to access index 0 (i.e. `ptr`), because
// 1 <= end < self.len(), which means self.len() >= 2.
let ptr = self.data.as_mut_ptr();
unsafe {
let ptr = self.data.as_mut_ptr();
ptr::swap(ptr, ptr.add(end));
}
self.sift_down_range(0, end);
Expand All @@ -960,47 +960,47 @@ impl<T, C: Compare<T>> BinaryHeap<T, C> {
// Using a hole reduces the constant factor compared to using swaps,
// which involves twice as many moves.
fn sift_up(&mut self, start: usize, pos: usize) -> usize {
unsafe {

// Take out the value at `pos` and create a hole.
let mut hole = Hole::new(&mut self.data, pos);
let mut hole = unsafe { Hole::new(&mut self.data, pos) };

while hole.pos() > start {
let parent = (hole.pos() - 1) / 2;
// if hole.element() <= hole.get(parent) {
if self.cmp.compare(hole.element(), hole.get(parent)) != Ordering::Greater {
if self.cmp.compare(hole.element(), unsafe { hole.get(parent) }) != Ordering::Greater {
break;
}
hole.move_to(parent);
unsafe { hole.move_to(parent) };
}
hole.pos()
}

}

/// Take an element at `pos` and move it down the heap,
/// while its children are larger.
fn sift_down_range(&mut self, pos: usize, end: usize) {
unsafe {
let mut hole = Hole::new(&mut self.data, pos);

let mut hole = unsafe { Hole::new(&mut self.data, pos) };
let mut child = 2 * pos + 1;
while child < end - 1 {
// compare with the greater of the two children
// if !(hole.get(child) > hole.get(child + 1)) { child += 1 }
child += (self.cmp.compare(hole.get(child), hole.get(child + 1))
child += (self.cmp.compare(unsafe { hole.get(child) }, unsafe { hole.get(child + 1) })
!= Ordering::Greater) as usize;
// if we are already in order, stop.
// if hole.element() >= hole.get(child) {
if self.cmp.compare(hole.element(), hole.get(child)) != Ordering::Less {
if self.cmp.compare(hole.element(), unsafe { hole.get(child) }) != Ordering::Less {
return;
}
hole.move_to(child);
unsafe { hole.move_to(child) };
child = 2 * hole.pos() + 1;
}
if child == end - 1
&& self.cmp.compare(hole.element(), hole.get(child)) == Ordering::Less
&& self.cmp.compare(hole.element(), unsafe { hole.get(child) }) == Ordering::Less
{
hole.move_to(child);
unsafe { hole.move_to(child) };
}
}

}

fn sift_down(&mut self, pos: usize) {
Expand Down