diff options
| -rw-r--r-- | library/alloc/src/collections/btree/node.rs | 31 |
1 files changed, 15 insertions, 16 deletions
diff --git a/library/alloc/src/collections/btree/node.rs b/library/alloc/src/collections/btree/node.rs index 4fc32305f1e..4d69d5d6803 100644 --- a/library/alloc/src/collections/btree/node.rs +++ b/library/alloc/src/collections/btree/node.rs @@ -78,9 +78,8 @@ impl<K, V> LeafNode<K, V> { } } - /// Creates a new boxed `LeafNode`. Unsafe because all nodes should really be hidden behind - /// `BoxedNode`, preventing accidental dropping of uninitialized keys and values. - unsafe fn new() -> Box<Self> { + /// Creates a new boxed `LeafNode`. + fn new() -> Box<Self> { unsafe { let mut leaf = Box::new_uninit(); LeafNode::init(leaf.as_mut_ptr()); @@ -108,10 +107,9 @@ struct InternalNode<K, V> { impl<K, V> InternalNode<K, V> { /// Creates a new boxed `InternalNode`. /// - /// This is unsafe for two reasons. First, it returns an owned `InternalNode` in a box, risking - /// dropping of uninitialized fields. Second, an invariant of internal nodes is that `len + 1` - /// edges are initialized and valid, meaning that even when the node is empty (having a - /// `len` of 0), there must be one initialized and valid edge. This function does not set up + /// # Safety + /// An invariant of internal nodes is that they have at least one + /// initialized and valid edge. This function does not set up /// such an edge. unsafe fn new() -> Box<Self> { unsafe { @@ -145,7 +143,7 @@ impl<K, V> Root<K, V> { impl<K, V> NodeRef<marker::Owned, K, V, marker::Leaf> { fn new_leaf() -> Self { - Self::from_new_leaf(unsafe { LeafNode::new() }) + Self::from_new_leaf(LeafNode::new()) } fn from_new_leaf(leaf: Box<LeafNode<K, V>>) -> Self { @@ -157,10 +155,13 @@ impl<K, V> NodeRef<marker::Owned, K, V, marker::Internal> { fn new_internal(child: Root<K, V>) -> Self { let mut new_node = unsafe { InternalNode::new() }; new_node.edges[0].write(child.node); - NodeRef::from_new_internal(new_node, child.height + 1) + unsafe { NodeRef::from_new_internal(new_node, child.height + 1) } } - fn from_new_internal(internal: Box<InternalNode<K, V>>, height: usize) -> Self { + /// # Safety + /// `height` must not be zero. + unsafe fn from_new_internal(internal: Box<InternalNode<K, V>>, height: usize) -> Self { + debug_assert!(height > 0); let node = NonNull::from(Box::leak(internal)).cast(); let mut this = NodeRef { height, node, _marker: PhantomData }; this.borrow_mut().correct_all_childrens_parent_links(); @@ -1086,14 +1087,12 @@ impl<'a, K: 'a, V: 'a> Handle<NodeRef<marker::Mut<'a>, K, V, marker::Leaf>, mark /// - All the key-value pairs to the right of this handle are put into a newly /// allocated node. pub fn split(mut self) -> SplitResult<'a, K, V, marker::Leaf> { - unsafe { - let mut new_node = LeafNode::new(); + let mut new_node = LeafNode::new(); - let kv = self.split_leaf_data(&mut new_node); + let kv = self.split_leaf_data(&mut new_node); - let right = NodeRef::from_new_leaf(new_node); - SplitResult { left: self.node, kv, right } - } + let right = NodeRef::from_new_leaf(new_node); + SplitResult { left: self.node, kv, right } } /// Removes the key-value pair pointed to by this handle and returns it, along with the edge |