BTreeMap: reuse NodeRef as Root, keep BoxedNode for edges only, ban U…

…nique

library/alloc/src/collections/btree/append.rs

@@ -34,7 +34,7 @@ impl<K, V> Root<K, V> {
  where
  I: Iterator<Item = (K, V)>,
  {
- let mut cur_node = self.node_as_mut().last_leaf_edge().into_node();
+ let mut cur_node = self.borrow_mut().last_leaf_edge().into_node();
  // Iterate through all key-value pairs, pushing them into nodes at the right level.
  for (key, value) in iter {
  // Try to push key-value pair into the current leaf node.
@@ -86,7 +86,7 @@ impl<K, V> Root<K, V> {
 
  fn fix_right_edge(&mut self) {
  // Handle underfull nodes, start from the top.
- let mut cur_node = self.node_as_mut();
+ let mut cur_node = self.borrow_mut();
  while let Internal(internal) = cur_node.force() {
  // Check if right-most child is underfull.
  let mut last_kv = internal.last_kv().consider_for_balancing();

library/alloc/src/collections/btree/map.rs

@@ -157,7 +157,7 @@ impl<K: Clone, V: Clone> Clone for BTreeMap<K, V> {
 
  {
  let root = out_tree.root.as_mut().unwrap(); // unwrap succeeds because we just wrapped
- let mut out_node = match root.node_as_mut().force() {
+ let mut out_node = match root.borrow_mut().force() {
  Leaf(leaf) => leaf,
  Internal(_) => unreachable!(),
  };
@@ -213,7 +213,7 @@ impl<K: Clone, V: Clone> Clone for BTreeMap<K, V> {
  // Ord` constraint, which this method lacks.
  BTreeMap { root: None, length: 0 }
  } else {
- clone_subtree(self.root.as_ref().unwrap().node_as_ref()) // unwrap succeeds because not empty
+ clone_subtree(self.root.as_ref().unwrap().reborrow()) // unwrap succeeds because not empty
  }
  }
 }
@@ -226,7 +226,7 @@ where
  type Key = K;
 
  fn get(&self, key: &Q) -> Option<&K> {
- let root_node = self.root.as_ref()?.node_as_ref();
+ let root_node = self.root.as_ref()?.reborrow();
  match search::search_tree(root_node, key) {
  Found(handle) => Some(handle.into_kv().0),
  GoDown(_) => None,
@@ -235,7 +235,7 @@ where
 
  fn take(&mut self, key: &Q) -> Option<K> {
  let (map, dormant_map) = DormantMutRef::new(self);
- let root_node = map.root.as_mut()?.node_as_mut();
+ let root_node = map.root.as_mut()?.borrow_mut();
  match search::search_tree(root_node, key) {
  Found(handle) => {
  Some(OccupiedEntry { handle, dormant_map, _marker: PhantomData }.remove_kv().0)
@@ -246,7 +246,7 @@ where
 
  fn replace(&mut self, key: K) -> Option<K> {
  let (map, dormant_map) = DormantMutRef::new(self);
- let root_node = Self::ensure_is_owned(&mut map.root).node_as_mut();
+ let root_node = Self::ensure_is_owned(&mut map.root).borrow_mut();
  match search::search_tree::<marker::Mut<'_>, K, (), K>(root_node, &key) {
  Found(handle) => Some(mem::replace(handle.into_key_mut(), key)),
  GoDown(handle) => {
@@ -522,7 +522,7 @@ impl<K: Ord, V> BTreeMap<K, V> {
  K: Borrow<Q>,
  Q: Ord,
  {
- let root_node = self.root.as_ref()?.node_as_ref();
+ let root_node = self.root.as_ref()?.reborrow();
  match search::search_tree(root_node, key) {
  Found(handle) => Some(handle.into_kv().1),
  GoDown(_) => None,
@@ -550,7 +550,7 @@ impl<K: Ord, V> BTreeMap<K, V> {
  K: Borrow<Q>,
  Q: Ord,
  {
- let root_node = self.root.as_ref()?.node_as_ref();
+ let root_node = self.root.as_ref()?.reborrow();
  match search::search_tree(root_node, k) {
  Found(handle) => Some(handle.into_kv()),
  GoDown(_) => None,
@@ -576,7 +576,7 @@ impl<K: Ord, V> BTreeMap<K, V> {
  /// ```
  #[unstable(feature = "map_first_last", issue = "62924")]
  pub fn first_key_value(&self) -> Option<(&K, &V)> {
- let root_node = self.root.as_ref()?.node_as_ref();
+ let root_node = self.root.as_ref()?.reborrow();
  root_node.first_leaf_edge().right_kv().ok().map(Handle::into_kv)
  }
 
@@ -603,7 +603,7 @@ impl<K: Ord, V> BTreeMap<K, V> {
  #[unstable(feature = "map_first_last", issue = "62924")]
  pub fn first_entry(&mut self) -> Option<OccupiedEntry<'_, K, V>> {
  let (map, dormant_map) = DormantMutRef::new(self);
- let root_node = map.root.as_mut()?.node_as_mut();
+ let root_node = map.root.as_mut()?.borrow_mut();
  let kv = root_node.first_leaf_edge().right_kv().ok()?;
  Some(OccupiedEntry { handle: kv.forget_node_type(), dormant_map, _marker: PhantomData })
  }
@@ -650,7 +650,7 @@ impl<K: Ord, V> BTreeMap<K, V> {
  /// ```
  #[unstable(feature = "map_first_last", issue = "62924")]
  pub fn last_key_value(&self) -> Option<(&K, &V)> {
- let root_node = self.root.as_ref()?.node_as_ref();
+ let root_node = self.root.as_ref()?.reborrow();
  root_node.last_leaf_edge().left_kv().ok().map(Handle::into_kv)
  }
 
@@ -677,7 +677,7 @@ impl<K: Ord, V> BTreeMap<K, V> {
  #[unstable(feature = "map_first_last", issue = "62924")]
  pub fn last_entry(&mut self) -> Option<OccupiedEntry<'_, K, V>> {
  let (map, dormant_map) = DormantMutRef::new(self);
- let root_node = map.root.as_mut()?.node_as_mut();
+ let root_node = map.root.as_mut()?.borrow_mut();
  let kv = root_node.last_leaf_edge().left_kv().ok()?;
  Some(OccupiedEntry { handle: kv.forget_node_type(), dormant_map, _marker: PhantomData })
  }
@@ -758,7 +758,7 @@ impl<K: Ord, V> BTreeMap<K, V> {
  K: Borrow<Q>,
  Q: Ord,
  {
- let root_node = self.root.as_mut()?.node_as_mut();
+ let root_node = self.root.as_mut()?.borrow_mut();
  match search::search_tree(root_node, key) {
  Found(handle) => Some(handle.into_val_mut()),
  GoDown(_) => None,
@@ -854,7 +854,7 @@ impl<K: Ord, V> BTreeMap<K, V> {
  Q: Ord,
  {
  let (map, dormant_map) = DormantMutRef::new(self);
- let root_node = map.root.as_mut()?.node_as_mut();
+ let root_node = map.root.as_mut()?.borrow_mut();
  match search::search_tree(root_node, key) {
  Found(handle) => {
  Some(OccupiedEntry { handle, dormant_map, _marker: PhantomData }.remove_entry())
@@ -971,7 +971,7 @@ impl<K: Ord, V> BTreeMap<K, V> {
  R: RangeBounds<T>,
  {
  if let Some(root) = &self.root {
- let (f, b) = root.node_as_ref().range_search(range);
+ let (f, b) = root.reborrow().range_search(range);
 
  Range { front: Some(f), back: Some(b) }
  } else {
@@ -1017,7 +1017,7 @@ impl<K: Ord, V> BTreeMap<K, V> {
  R: RangeBounds<T>,
  {
  if let Some(root) = &mut self.root {
- let (f, b) = root.node_as_valmut().range_search(range);
+ let (f, b) = root.borrow_valmut().range_search(range);
 
  RangeMut { front: Some(f), back: Some(b), _marker: PhantomData }
  } else {
@@ -1047,7 +1047,7 @@ impl<K: Ord, V> BTreeMap<K, V> {
  pub fn entry(&mut self, key: K) -> Entry<'_, K, V> {
  // FIXME(@porglezomp) Avoid allocating if we don't insert
  let (map, dormant_map) = DormantMutRef::new(self);
- let root_node = Self::ensure_is_owned(&mut map.root).node_as_mut();
+ let root_node = Self::ensure_is_owned(&mut map.root).borrow_mut();
  match search::search_tree(root_node, &key) {
  Found(handle) => Occupied(OccupiedEntry { handle, dormant_map, _marker: PhantomData }),
  GoDown(handle) => {
@@ -1103,10 +1103,10 @@ impl<K: Ord, V> BTreeMap<K, V> {
  left_root.split_off(right_root, key);
 
  if left_root.height() < right_root.height() {
- self.length = left_root.node_as_ref().calc_length();
+ self.length = left_root.reborrow().calc_length();
  right.length = total_num - self.len();
  } else {
- right.length = right_root.node_as_ref().calc_length();
+ right.length = right_root.reborrow().calc_length();
  self.length = total_num - right.len();
  }
 
@@ -1154,7 +1154,7 @@ impl<K: Ord, V> BTreeMap<K, V> {
  pub(super) fn drain_filter_inner(&mut self) -> DrainFilterInner<'_, K, V> {
  if let Some(root) = self.root.as_mut() {
  let (root, dormant_root) = DormantMutRef::new(root);
- let front = root.node_as_mut().first_leaf_edge();
+ let front = root.borrow_mut().first_leaf_edge();
  DrainFilterInner {
  length: &mut self.length,
  dormant_root: Some(dormant_root),
@@ -1361,7 +1361,7 @@ impl<K, V> IntoIterator for BTreeMap<K, V> {
  fn into_iter(self) -> IntoIter<K, V> {
  let mut me = ManuallyDrop::new(self);
  if let Some(root) = me.root.take() {
- let (f, b) = root.into_ref().full_range();
+ let (f, b) = root.full_range();
 
  IntoIter { front: Some(f), back: Some(b), length: me.length }
  } else {
@@ -2007,7 +2007,7 @@ impl<K, V> BTreeMap<K, V> {
  #[stable(feature = "rust1", since = "1.0.0")]
  pub fn iter(&self) -> Iter<'_, K, V> {
  if let Some(root) = &self.root {
- let (f, b) = root.node_as_ref().full_range();
+ let (f, b) = root.reborrow().full_range();
 
  Iter { range: Range { front: Some(f), back: Some(b) }, length: self.length }
  } else {
@@ -2039,7 +2039,7 @@ impl<K, V> BTreeMap<K, V> {
  #[stable(feature = "rust1", since = "1.0.0")]
  pub fn iter_mut(&mut self) -> IterMut<'_, K, V> {
  if let Some(root) = &mut self.root {
- let (f, b) = root.node_as_valmut().full_range();
+ let (f, b) = root.borrow_valmut().full_range();
 
  IterMut {
  range: RangeMut { front: Some(f), back: Some(b), _marker: PhantomData },

library/alloc/src/collections/btree/map/entry.rs

@@ -286,7 +286,7 @@ impl<'a, K: Ord, V> VacantEntry<'a, K, V> {
  // Safety: We have consumed self.handle and the reference returned.
  let map = unsafe { self.dormant_map.awaken() };
  let root = map.root.as_mut().unwrap();
- root.push_internal_level().push(ins.k, ins.v, ins.right);
+ root.push_internal_level().push(ins.kv.0, ins.kv.1, ins.right);
  map.length += 1;
  val_ptr
  }

library/alloc/src/collections/btree/map/tests.rs

@@ -49,7 +49,7 @@ impl<K, V> BTreeMap<K, V> {
  // Panics if the map (or the code navigating it) is corrupted.
  fn check_invariants(&self) {
  if let Some(root) = &self.root {
- let root_node = root.node_as_ref();
+ let root_node = root.reborrow();
 
  // Check the back pointers top-down, before we attempt to rely on
  // more serious navigation code.
@@ -92,7 +92,7 @@ impl<K, V> BTreeMap<K, V> {
  K: Debug,
  {
  if let Some(root) = self.root.as_ref() {
- root.node_as_ref().dump_keys()
+ root.reborrow().dump_keys()
  } else {
  String::from("not yet allocated")
  }