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BTreeMap: introduce edge methods similar to those of keys and values

This commit is contained in:
Stein Somers 2020-08-09 12:25:20 +02:00
parent 1e64d98761
commit 3965524570
1 changed files with 34 additions and 24 deletions
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58
library/alloc/src/collections/btree/node.rs
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@ -351,7 +351,22 @@ impl<BorrowType, K, V, Type> NodeRef<BorrowType, K, V, Type> {
unsafe fn val_at(&self, idx: usize) -> &V {
unsafe { self.reborrow().into_val_at(idx) }
}
}
impl<BorrowType, K, V> NodeRef<BorrowType, K, V, marker::Internal> {
/// Borrows a reference to the contents of one of the edges that delimit
/// the elements of the node, without invalidating other references.
///
/// # Safety
/// The node has more than `idx` initialized elements.
unsafe fn edge_at(&self, idx: usize) -> &BoxedNode<K, V> {
debug_assert!(idx <= self.len());
let node = self.as_internal_ptr();
unsafe { (*node).edges.get_unchecked(idx).assume_init_ref() }
}
}
impl<BorrowType, K, V, Type> NodeRef<BorrowType, K, V, Type> {
/// Finds the parent of the current node. Returns `Ok(handle)` if the current
/// node actually has a parent, where `handle` points to the edge of the parent
/// that points to the current node. Returns `Err(self)` if the current node has
@ -498,6 +513,17 @@ impl<'a, K, V, Type> NodeRef<marker::Mut<'a>, K, V, Type> {
}
}
impl<'a, K, V> NodeRef<marker::Mut<'a>, K, V, marker::Internal> {
fn edges_mut(&mut self) -> &mut [BoxedNode<K, V>] {
unsafe {
slice::from_raw_parts_mut(
MaybeUninit::slice_as_mut_ptr(&mut self.as_internal_mut().edges),
self.len() + 1,
)
}
}
}
impl<'a, K: 'a, V: 'a, Type> NodeRef<marker::Immut<'a>, K, V, Type> {
/// # Safety
/// The node has more than `idx` initialized elements.
@ -669,9 +695,8 @@ impl<'a, K: 'a, V: 'a> NodeRef<marker::Mut<'a>, K, V, marker::LeafOrInternal> {
let val = ptr::read(self.val_at(idx));
let edge = match self.reborrow_mut().force() {
ForceResult::Leaf(_) => None,
ForceResult::Internal(mut internal) => {
let edge =
ptr::read(internal.as_internal().edges.get_unchecked(idx + 1).as_ptr());
ForceResult::Internal(internal) => {
let edge = ptr::read(internal.edge_at(idx + 1));
let mut new_root = Root { node: edge, height: internal.height - 1 };
new_root.node_as_mut().as_leaf_mut().parent = None;
Some(new_root)
@ -696,14 +721,7 @@ impl<'a, K: 'a, V: 'a> NodeRef<marker::Mut<'a>, K, V, marker::LeafOrInternal> {
let edge = match self.reborrow_mut().force() {
ForceResult::Leaf(_) => None,
ForceResult::Internal(mut internal) => {
let edge = slice_remove(
slice::from_raw_parts_mut(
MaybeUninit::slice_as_mut_ptr(&mut internal.as_internal_mut().edges),
old_len + 1,
),
0,
);
let edge = slice_remove(internal.edges_mut(), 0);
let mut new_root = Root { node: edge, height: internal.height - 1 };
new_root.node_as_mut().as_leaf_mut().parent = None;
@ -972,17 +990,9 @@ impl<'a, K: 'a, V: 'a> Handle<NodeRef<marker::Mut<'a>, K, V, marker::Internal>,
debug_assert!(edge.height == self.node.height - 1);
unsafe {
slice_insert(self.node.edges_mut(), self.idx + 1, edge.node);
self.leafy_insert_fit(key, val);
slice_insert(
slice::from_raw_parts_mut(
MaybeUninit::slice_as_mut_ptr(&mut self.node.as_internal_mut().edges),
self.node.len(),
),
self.idx + 1,
edge.node,
);
self.node.correct_childrens_parent_links((self.idx + 1)..=self.node.len());
}
}
@ -1253,7 +1263,7 @@ impl<'a, K: 'a, V: 'a> Handle<NodeRef<marker::Mut<'a>, K, V, marker::Internal>,
right_len,
);
slice_remove(&mut self.node.as_internal_mut().edges, self.idx + 1);
slice_remove(&mut self.node.edges_mut(), self.idx + 1);
let self_len = self.node.len();
self.node.correct_childrens_parent_links(self.idx + 1..self_len);
self.node.as_leaf_mut().len -= 1;
@ -1264,10 +1274,10 @@ impl<'a, K: 'a, V: 'a> Handle<NodeRef<marker::Mut<'a>, K, V, marker::Internal>,
// SAFETY: the height of the nodes being merged is one below the height
// of the node of this edge, thus above zero, so they are internal.
let mut left_node = left_node.cast_unchecked::<marker::Internal>();
let mut right_node = right_node.cast_unchecked::<marker::Internal>();
let right_node = right_node.cast_unchecked::<marker::Internal>();
ptr::copy_nonoverlapping(
right_node.as_internal().edges.as_ptr(),
left_node.as_internal_mut().edges.as_mut_ptr().add(left_len + 1),
right_node.edge_at(0),
left_node.edges_mut().as_mut_ptr().add(left_len + 1),
right_len + 1,
);