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use core::borrow::Borrow;
use core::hint;
use core::ops::RangeBounds;
use core::ptr;
use super::node::{marker, ForceResult::*, Handle, NodeRef};
use super::search::SearchBound;
use crate::alloc::Allocator;
// `front` and `back` are always both `None` or both `Some`.
pub struct LeafRange<BorrowType, K, V> {
front: Option<Handle<NodeRef<BorrowType, K, V, marker::Leaf>, marker::Edge>>,
back: Option<Handle<NodeRef<BorrowType, K, V, marker::Leaf>, marker::Edge>>,
}
impl<'a, K: 'a, V: 'a> Clone for LeafRange<marker::Immut<'a>, K, V> {
fn clone(&self) -> Self {
LeafRange { front: self.front.clone(), back: self.back.clone() }
}
}
impl<B, K, V> Default for LeafRange<B, K, V> {
fn default() -> Self {
LeafRange { front: None, back: None }
}
}
impl<BorrowType, K, V> LeafRange<BorrowType, K, V> {
pub fn none() -> Self {
LeafRange { front: None, back: None }
}
fn is_empty(&self) -> bool {
self.front == self.back
}
/// Temporarily takes out another, immutable equivalent of the same range.
pub fn reborrow(&self) -> LeafRange<marker::Immut<'_>, K, V> {
LeafRange {
front: self.front.as_ref().map(|f| f.reborrow()),
back: self.back.as_ref().map(|b| b.reborrow()),
}
}
}
impl<'a, K, V> LeafRange<marker::Immut<'a>, K, V> {
#[inline]
pub fn next_checked(&mut self) -> Option<(&'a K, &'a V)> {
self.perform_next_checked(|kv| kv.into_kv())
}
#[inline]
pub fn next_back_checked(&mut self) -> Option<(&'a K, &'a V)> {
self.perform_next_back_checked(|kv| kv.into_kv())
}
}
impl<'a, K, V> LeafRange<marker::ValMut<'a>, K, V> {
#[inline]
pub fn next_checked(&mut self) -> Option<(&'a K, &'a mut V)> {
self.perform_next_checked(|kv| unsafe { ptr::read(kv) }.into_kv_valmut())
}
#[inline]
pub fn next_back_checked(&mut self) -> Option<(&'a K, &'a mut V)> {
self.perform_next_back_checked(|kv| unsafe { ptr::read(kv) }.into_kv_valmut())
}
}
impl<BorrowType: marker::BorrowType, K, V> LeafRange<BorrowType, K, V> {
/// If possible, extract some result from the following KV and move to the edge beyond it.
fn perform_next_checked<F, R>(&mut self, f: F) -> Option<R>
where
F: Fn(&Handle<NodeRef<BorrowType, K, V, marker::LeafOrInternal>, marker::KV>) -> R,
{
if self.is_empty() {
None
} else {
super::mem::replace(self.front.as_mut().unwrap(), |front| {
let kv = front.next_kv().ok().unwrap();
let result = f(&kv);
(kv.next_leaf_edge(), Some(result))
})
}
}
/// If possible, extract some result from the preceding KV and move to the edge beyond it.
fn perform_next_back_checked<F, R>(&mut self, f: F) -> Option<R>
where
F: Fn(&Handle<NodeRef<BorrowType, K, V, marker::LeafOrInternal>, marker::KV>) -> R,
{
if self.is_empty() {
None
} else {
super::mem::replace(self.back.as_mut().unwrap(), |back| {
let kv = back.next_back_kv().ok().unwrap();
let result = f(&kv);
(kv.next_back_leaf_edge(), Some(result))
})
}
}
}
enum LazyLeafHandle<BorrowType, K, V> {
Root(NodeRef<BorrowType, K, V, marker::LeafOrInternal>), // not yet descended
Edge(Handle<NodeRef<BorrowType, K, V, marker::Leaf>, marker::Edge>),
}
impl<'a, K: 'a, V: 'a> Clone for LazyLeafHandle<marker::Immut<'a>, K, V> {
fn clone(&self) -> Self {
match self {
LazyLeafHandle::Root(root) => LazyLeafHandle::Root(*root),
LazyLeafHandle::Edge(edge) => LazyLeafHandle::Edge(*edge),
}
}
}
impl<BorrowType, K, V> LazyLeafHandle<BorrowType, K, V> {
fn reborrow(&self) -> LazyLeafHandle<marker::Immut<'_>, K, V> {
match self {
LazyLeafHandle::Root(root) => LazyLeafHandle::Root(root.reborrow()),
LazyLeafHandle::Edge(edge) => LazyLeafHandle::Edge(edge.reborrow()),
}
}
}
// `front` and `back` are always both `None` or both `Some`.
pub struct LazyLeafRange<BorrowType, K, V> {
front: Option<LazyLeafHandle<BorrowType, K, V>>,
back: Option<LazyLeafHandle<BorrowType, K, V>>,
}
impl<B, K, V> Default for LazyLeafRange<B, K, V> {
fn default() -> Self {
LazyLeafRange { front: None, back: None }
}
}
impl<'a, K: 'a, V: 'a> Clone for LazyLeafRange<marker::Immut<'a>, K, V> {
fn clone(&self) -> Self {
LazyLeafRange { front: self.front.clone(), back: self.back.clone() }
}
}
impl<BorrowType, K, V> LazyLeafRange<BorrowType, K, V> {
pub fn none() -> Self {
LazyLeafRange { front: None, back: None }
}
/// Temporarily takes out another, immutable equivalent of the same range.
pub fn reborrow(&self) -> LazyLeafRange<marker::Immut<'_>, K, V> {
LazyLeafRange {
front: self.front.as_ref().map(|f| f.reborrow()),
back: self.back.as_ref().map(|b| b.reborrow()),
}
}
}
impl<'a, K, V> LazyLeafRange<marker::Immut<'a>, K, V> {
#[inline]
pub unsafe fn next_unchecked(&mut self) -> (&'a K, &'a V) {
unsafe { self.init_front().unwrap().next_unchecked() }
}
#[inline]
pub unsafe fn next_back_unchecked(&mut self) -> (&'a K, &'a V) {
unsafe { self.init_back().unwrap().next_back_unchecked() }
}
}
impl<'a, K, V> LazyLeafRange<marker::ValMut<'a>, K, V> {
#[inline]
pub unsafe fn next_unchecked(&mut self) -> (&'a K, &'a mut V) {
unsafe { self.init_front().unwrap().next_unchecked() }
}
#[inline]
pub unsafe fn next_back_unchecked(&mut self) -> (&'a K, &'a mut V) {
unsafe { self.init_back().unwrap().next_back_unchecked() }
}
}
impl<K, V> LazyLeafRange<marker::Dying, K, V> {
fn take_front(
&mut self,
) -> Option<Handle<NodeRef<marker::Dying, K, V, marker::Leaf>, marker::Edge>> {
match self.front.take()? {
LazyLeafHandle::Root(root) => Some(root.first_leaf_edge()),
LazyLeafHandle::Edge(edge) => Some(edge),
}
}
#[inline]
pub unsafe fn deallocating_next_unchecked<A: Allocator + Clone>(
&mut self,
alloc: A,
) -> Handle<NodeRef<marker::Dying, K, V, marker::LeafOrInternal>, marker::KV> {
debug_assert!(self.front.is_some());
let front = self.init_front().unwrap();
unsafe { front.deallocating_next_unchecked(alloc) }
}
#[inline]
pub unsafe fn deallocating_next_back_unchecked<A: Allocator + Clone>(
&mut self,
alloc: A,
) -> Handle<NodeRef<marker::Dying, K, V, marker::LeafOrInternal>, marker::KV> {
debug_assert!(self.back.is_some());
let back = self.init_back().unwrap();
unsafe { back.deallocating_next_back_unchecked(alloc) }
}
#[inline]
pub fn deallocating_end<A: Allocator + Clone>(&mut self, alloc: A) {
if let Some(front) = self.take_front() {
front.deallocating_end(alloc)
}
}
}
impl<BorrowType: marker::BorrowType, K, V> LazyLeafRange<BorrowType, K, V> {
fn init_front(
&mut self,
) -> Option<&mut Handle<NodeRef<BorrowType, K, V, marker::Leaf>, marker::Edge>> {
if let Some(LazyLeafHandle::Root(root)) = &self.front {
self.front = Some(LazyLeafHandle::Edge(unsafe { ptr::read(root) }.first_leaf_edge()));
}
match &mut self.front {
None => None,
Some(LazyLeafHandle::Edge(edge)) => Some(edge),
// SAFETY: the code above would have replaced it.
Some(LazyLeafHandle::Root(_)) => unsafe { hint::unreachable_unchecked() },
}
}
fn init_back(
&mut self,
) -> Option<&mut Handle<NodeRef<BorrowType, K, V, marker::Leaf>, marker::Edge>> {
if let Some(LazyLeafHandle::Root(root)) = &self.back {
self.back = Some(LazyLeafHandle::Edge(unsafe { ptr::read(root) }.last_leaf_edge()));
}
match &mut self.back {
None => None,
Some(LazyLeafHandle::Edge(edge)) => Some(edge),
// SAFETY: the code above would have replaced it.
Some(LazyLeafHandle::Root(_)) => unsafe { hint::unreachable_unchecked() },
}
}
}
impl<BorrowType: marker::BorrowType, K, V> NodeRef<BorrowType, K, V, marker::LeafOrInternal> {
/// Finds the distinct leaf edges delimiting a specified range in a tree.
///
/// If such distinct edges exist, returns them in ascending order, meaning
/// that a non-zero number of calls to `next_unchecked` on the `front` of
/// the result and/or calls to `next_back_unchecked` on the `back` of the
/// result will eventually reach the same edge.
///
/// If there are no such edges, i.e., if the tree contains no key within
/// the range, returns an empty `front` and `back`.
///
/// # Safety
/// Unless `BorrowType` is `Immut`, do not use the handles to visit the same
/// KV twice.
unsafe fn find_leaf_edges_spanning_range<Q: ?Sized, R>(
self,
range: R,
) -> LeafRange<BorrowType, K, V>
where
Q: Ord,
K: Borrow<Q>,
R: RangeBounds<Q>,
{
match self.search_tree_for_bifurcation(&range) {
Err(_) => LeafRange::none(),
Ok((
node,
lower_edge_idx,
upper_edge_idx,
mut lower_child_bound,
mut upper_child_bound,
)) => {
let mut lower_edge = unsafe { Handle::new_edge(ptr::read(&node), lower_edge_idx) };
let mut upper_edge = unsafe { Handle::new_edge(node, upper_edge_idx) };
loop {
match (lower_edge.force(), upper_edge.force()) {
(Leaf(f), Leaf(b)) => return LeafRange { front: Some(f), back: Some(b) },
(Internal(f), Internal(b)) => {
(lower_edge, lower_child_bound) =
f.descend().find_lower_bound_edge(lower_child_bound);
(upper_edge, upper_child_bound) =
b.descend().find_upper_bound_edge(upper_child_bound);
}
_ => unreachable!("BTreeMap has different depths"),
}
}
}
}
}
}
fn full_range<BorrowType: marker::BorrowType, K, V>(
root1: NodeRef<BorrowType, K, V, marker::LeafOrInternal>,
root2: NodeRef<BorrowType, K, V, marker::LeafOrInternal>,
) -> LazyLeafRange<BorrowType, K, V> {
LazyLeafRange {
front: Some(LazyLeafHandle::Root(root1)),
back: Some(LazyLeafHandle::Root(root2)),
}
}
impl<'a, K: 'a, V: 'a> NodeRef<marker::Immut<'a>, K, V, marker::LeafOrInternal> {
/// Finds the pair of leaf edges delimiting a specific range in a tree.
///
/// The result is meaningful only if the tree is ordered by key, like the tree
/// in a `BTreeMap` is.
pub fn range_search<Q, R>(self, range: R) -> LeafRange<marker::Immut<'a>, K, V>
where
Q: ?Sized + Ord,
K: Borrow<Q>,
R: RangeBounds<Q>,
{
// SAFETY: our borrow type is immutable.
unsafe { self.find_leaf_edges_spanning_range(range) }
}
/// Finds the pair of leaf edges delimiting an entire tree.
pub fn full_range(self) -> LazyLeafRange<marker::Immut<'a>, K, V> {
full_range(self, self)
}
}
impl<'a, K: 'a, V: 'a> NodeRef<marker::ValMut<'a>, K, V, marker::LeafOrInternal> {
/// Splits a unique reference into a pair of leaf edges delimiting a specified range.
/// The result are non-unique references allowing (some) mutation, which must be used
/// carefully.
///
/// The result is meaningful only if the tree is ordered by key, like the tree
/// in a `BTreeMap` is.
///
/// # Safety
/// Do not use the duplicate handles to visit the same KV twice.
pub fn range_search<Q, R>(self, range: R) -> LeafRange<marker::ValMut<'a>, K, V>
where
Q: ?Sized + Ord,
K: Borrow<Q>,
R: RangeBounds<Q>,
{
unsafe { self.find_leaf_edges_spanning_range(range) }
}
/// Splits a unique reference into a pair of leaf edges delimiting the full range of the tree.
/// The results are non-unique references allowing mutation (of values only), so must be used
/// with care.
pub fn full_range(self) -> LazyLeafRange<marker::ValMut<'a>, K, V> {
// We duplicate the root NodeRef here -- we will never visit the same KV
// twice, and never end up with overlapping value references.
let self2 = unsafe { ptr::read(&self) };
full_range(self, self2)
}
}
impl<K, V> NodeRef<marker::Dying, K, V, marker::LeafOrInternal> {
/// Splits a unique reference into a pair of leaf edges delimiting the full range of the tree.
/// The results are non-unique references allowing massively destructive mutation, so must be
/// used with the utmost care.
pub fn full_range(self) -> LazyLeafRange<marker::Dying, K, V> {
// We duplicate the root NodeRef here -- we will never access it in a way
// that overlaps references obtained from the root.
let self2 = unsafe { ptr::read(&self) };
full_range(self, self2)
}
}
impl<BorrowType: marker::BorrowType, K, V>
Handle<NodeRef<BorrowType, K, V, marker::Leaf>, marker::Edge>
{
/// Given a leaf edge handle, returns [`Result::Ok`] with a handle to the neighboring KV
/// on the right side, which is either in the same leaf node or in an ancestor node.
/// If the leaf edge is the last one in the tree, returns [`Result::Err`] with the root node.
pub fn next_kv(
self,
) -> Result<
Handle<NodeRef<BorrowType, K, V, marker::LeafOrInternal>, marker::KV>,
NodeRef<BorrowType, K, V, marker::LeafOrInternal>,
> {
let mut edge = self.forget_node_type();
loop {
edge = match edge.right_kv() {
Ok(kv) => return Ok(kv),
Err(last_edge) => match last_edge.into_node().ascend() {
Ok(parent_edge) => parent_edge.forget_node_type(),
Err(root) => return Err(root),
},
}
}
}
/// Given a leaf edge handle, returns [`Result::Ok`] with a handle to the neighboring KV
/// on the left side, which is either in the same leaf node or in an ancestor node.
/// If the leaf edge is the first one in the tree, returns [`Result::Err`] with the root node.
pub fn next_back_kv(
self,
) -> Result<
Handle<NodeRef<BorrowType, K, V, marker::LeafOrInternal>, marker::KV>,
NodeRef<BorrowType, K, V, marker::LeafOrInternal>,
> {
let mut edge = self.forget_node_type();
loop {
edge = match edge.left_kv() {
Ok(kv) => return Ok(kv),
Err(last_edge) => match last_edge.into_node().ascend() {
Ok(parent_edge) => parent_edge.forget_node_type(),
Err(root) => return Err(root),
},
}
}
}
}
impl<BorrowType: marker::BorrowType, K, V>
Handle<NodeRef<BorrowType, K, V, marker::Internal>, marker::Edge>
{
/// Given an internal edge handle, returns [`Result::Ok`] with a handle to the neighboring KV
/// on the right side, which is either in the same internal node or in an ancestor node.
/// If the internal edge is the last one in the tree, returns [`Result::Err`] with the root node.
fn next_kv(
self,
) -> Result<
Handle<NodeRef<BorrowType, K, V, marker::Internal>, marker::KV>,
NodeRef<BorrowType, K, V, marker::Internal>,
> {
let mut edge = self;
loop {
edge = match edge.right_kv() {
Ok(internal_kv) => return Ok(internal_kv),
Err(last_edge) => match last_edge.into_node().ascend() {
Ok(parent_edge) => parent_edge,
Err(root) => return Err(root),
},
}
}
}
}
impl<K, V> Handle<NodeRef<marker::Dying, K, V, marker::Leaf>, marker::Edge> {
/// Given a leaf edge handle into a dying tree, returns the next leaf edge
/// on the right side, and the key-value pair in between, if they exist.
///
/// If the given edge is the last one in a leaf, this method deallocates
/// the leaf, as well as any ancestor nodes whose last edge was reached.
/// This implies that if no more key-value pair follows, the entire tree
/// will have been deallocated and there is nothing left to return.
///
/// # Safety
/// - The given edge must not have been previously returned by counterpart
/// `deallocating_next_back`.
/// - The returned KV handle is only valid to access the key and value,
/// and only valid until the next call to a `deallocating_` method.
unsafe fn deallocating_next<A: Allocator + Clone>(
self,
alloc: A,
) -> Option<(Self, Handle<NodeRef<marker::Dying, K, V, marker::LeafOrInternal>, marker::KV>)>
{
let mut edge = self.forget_node_type();
loop {
edge = match edge.right_kv() {
Ok(kv) => return Some((unsafe { ptr::read(&kv) }.next_leaf_edge(), kv)),
Err(last_edge) => {
match unsafe { last_edge.into_node().deallocate_and_ascend(alloc.clone()) } {
Some(parent_edge) => parent_edge.forget_node_type(),
None => return None,
}
}
}
}
}
/// Given a leaf edge handle into a dying tree, returns the next leaf edge
/// on the left side, and the key-value pair in between, if they exist.
///
/// If the given edge is the first one in a leaf, this method deallocates
/// the leaf, as well as any ancestor nodes whose first edge was reached.
/// This implies that if no more key-value pair follows, the entire tree
/// will have been deallocated and there is nothing left to return.
///
/// # Safety
/// - The given edge must not have been previously returned by counterpart
/// `deallocating_next`.
/// - The returned KV handle is only valid to access the key and value,
/// and only valid until the next call to a `deallocating_` method.
unsafe fn deallocating_next_back<A: Allocator + Clone>(
self,
alloc: A,
) -> Option<(Self, Handle<NodeRef<marker::Dying, K, V, marker::LeafOrInternal>, marker::KV>)>
{
let mut edge = self.forget_node_type();
loop {
edge = match edge.left_kv() {
Ok(kv) => return Some((unsafe { ptr::read(&kv) }.next_back_leaf_edge(), kv)),
Err(last_edge) => {
match unsafe { last_edge.into_node().deallocate_and_ascend(alloc.clone()) } {
Some(parent_edge) => parent_edge.forget_node_type(),
None => return None,
}
}
}
}
}
/// Deallocates a pile of nodes from the leaf up to the root.
/// This is the only way to deallocate the remainder of a tree after
/// `deallocating_next` and `deallocating_next_back` have been nibbling at
/// both sides of the tree, and have hit the same edge. As it is intended
/// only to be called when all keys and values have been returned,
/// no cleanup is done on any of the keys or values.
fn deallocating_end<A: Allocator + Clone>(self, alloc: A) {
let mut edge = self.forget_node_type();
while let Some(parent_edge) =
unsafe { edge.into_node().deallocate_and_ascend(alloc.clone()) }
{
edge = parent_edge.forget_node_type();
}
}
}
impl<'a, K, V> Handle<NodeRef<marker::Immut<'a>, K, V, marker::Leaf>, marker::Edge> {
/// Moves the leaf edge handle to the next leaf edge and returns references to the
/// key and value in between.
///
/// # Safety
/// There must be another KV in the direction travelled.
unsafe fn next_unchecked(&mut self) -> (&'a K, &'a V) {
super::mem::replace(self, |leaf_edge| {
let kv = leaf_edge.next_kv().ok().unwrap();
(kv.next_leaf_edge(), kv.into_kv())
})
}
/// Moves the leaf edge handle to the previous leaf edge and returns references to the
/// key and value in between.
///
/// # Safety
/// There must be another KV in the direction travelled.
unsafe fn next_back_unchecked(&mut self) -> (&'a K, &'a V) {
super::mem::replace(self, |leaf_edge| {
let kv = leaf_edge.next_back_kv().ok().unwrap();
(kv.next_back_leaf_edge(), kv.into_kv())
})
}
}
impl<'a, K, V> Handle<NodeRef<marker::ValMut<'a>, K, V, marker::Leaf>, marker::Edge> {
/// Moves the leaf edge handle to the next leaf edge and returns references to the
/// key and value in between.
///
/// # Safety
/// There must be another KV in the direction travelled.
unsafe fn next_unchecked(&mut self) -> (&'a K, &'a mut V) {
let kv = super::mem::replace(self, |leaf_edge| {
let kv = leaf_edge.next_kv().ok().unwrap();
(unsafe { ptr::read(&kv) }.next_leaf_edge(), kv)
});
// Doing this last is faster, according to benchmarks.
kv.into_kv_valmut()
}
/// Moves the leaf edge handle to the previous leaf and returns references to the
/// key and value in between.
///
/// # Safety
/// There must be another KV in the direction travelled.
unsafe fn next_back_unchecked(&mut self) -> (&'a K, &'a mut V) {
let kv = super::mem::replace(self, |leaf_edge| {
let kv = leaf_edge.next_back_kv().ok().unwrap();
(unsafe { ptr::read(&kv) }.next_back_leaf_edge(), kv)
});
// Doing this last is faster, according to benchmarks.
kv.into_kv_valmut()
}
}
impl<K, V> Handle<NodeRef<marker::Dying, K, V, marker::Leaf>, marker::Edge> {
/// Moves the leaf edge handle to the next leaf edge and returns the key and value
/// in between, deallocating any node left behind while leaving the corresponding
/// edge in its parent node dangling.
///
/// # Safety
/// - There must be another KV in the direction travelled.
/// - That KV was not previously returned by counterpart
/// `deallocating_next_back_unchecked` on any copy of the handles
/// being used to traverse the tree.
///
/// The only safe way to proceed with the updated handle is to compare it, drop it,
/// or call this method or counterpart `deallocating_next_back_unchecked` again.
unsafe fn deallocating_next_unchecked<A: Allocator + Clone>(
&mut self,
alloc: A,
) -> Handle<NodeRef<marker::Dying, K, V, marker::LeafOrInternal>, marker::KV> {
super::mem::replace(self, |leaf_edge| unsafe {
leaf_edge.deallocating_next(alloc).unwrap()
})
}
/// Moves the leaf edge handle to the previous leaf edge and returns the key and value
/// in between, deallocating any node left behind while leaving the corresponding
/// edge in its parent node dangling.
///
/// # Safety
/// - There must be another KV in the direction travelled.
/// - That leaf edge was not previously returned by counterpart
/// `deallocating_next_unchecked` on any copy of the handles
/// being used to traverse the tree.
///
/// The only safe way to proceed with the updated handle is to compare it, drop it,
/// or call this method or counterpart `deallocating_next_unchecked` again.
unsafe fn deallocating_next_back_unchecked<A: Allocator + Clone>(
&mut self,
alloc: A,
) -> Handle<NodeRef<marker::Dying, K, V, marker::LeafOrInternal>, marker::KV> {
super::mem::replace(self, |leaf_edge| unsafe {
leaf_edge.deallocating_next_back(alloc).unwrap()
})
}
}
impl<BorrowType: marker::BorrowType, K, V> NodeRef<BorrowType, K, V, marker::LeafOrInternal> {
/// Returns the leftmost leaf edge in or underneath a node - in other words, the edge
/// you need first when navigating forward (or last when navigating backward).
#[inline]
pub fn first_leaf_edge(self) -> Handle<NodeRef<BorrowType, K, V, marker::Leaf>, marker::Edge> {
let mut node = self;
loop {
match node.force() {
Leaf(leaf) => return leaf.first_edge(),
Internal(internal) => node = internal.first_edge().descend(),
}
}
}
/// Returns the rightmost leaf edge in or underneath a node - in other words, the edge
/// you need last when navigating forward (or first when navigating backward).
#[inline]
pub fn last_leaf_edge(self) -> Handle<NodeRef<BorrowType, K, V, marker::Leaf>, marker::Edge> {
let mut node = self;
loop {
match node.force() {
Leaf(leaf) => return leaf.last_edge(),
Internal(internal) => node = internal.last_edge().descend(),
}
}
}
}
pub enum Position<BorrowType, K, V> {
Leaf(NodeRef<BorrowType, K, V, marker::Leaf>),
Internal(NodeRef<BorrowType, K, V, marker::Internal>),
InternalKV(Handle<NodeRef<BorrowType, K, V, marker::Internal>, marker::KV>),
}
impl<'a, K: 'a, V: 'a> NodeRef<marker::Immut<'a>, K, V, marker::LeafOrInternal> {
/// Visits leaf nodes and internal KVs in order of ascending keys, and also
/// visits internal nodes as a whole in a depth first order, meaning that
/// internal nodes precede their individual KVs and their child nodes.
pub fn visit_nodes_in_order<F>(self, mut visit: F)
where
F: FnMut(Position<marker::Immut<'a>, K, V>),
{
match self.force() {
Leaf(leaf) => visit(Position::Leaf(leaf)),
Internal(internal) => {
visit(Position::Internal(internal));
let mut edge = internal.first_edge();
loop {
edge = match edge.descend().force() {
Leaf(leaf) => {
visit(Position::Leaf(leaf));
match edge.next_kv() {
Ok(kv) => {
visit(Position::InternalKV(kv));
kv.right_edge()
}
Err(_) => return,
}
}
Internal(internal) => {
visit(Position::Internal(internal));
internal.first_edge()
}
}
}
}
}
}
/// Calculates the number of elements in a (sub)tree.
pub fn calc_length(self) -> usize {
let mut result = 0;
self.visit_nodes_in_order(|pos| match pos {
Position::Leaf(node) => result += node.len(),
Position::Internal(node) => result += node.len(),
Position::InternalKV(_) => (),
});
result
}
}
impl<BorrowType: marker::BorrowType, K, V>
Handle<NodeRef<BorrowType, K, V, marker::LeafOrInternal>, marker::KV>
{
/// Returns the leaf edge closest to a KV for forward navigation.
pub fn next_leaf_edge(self) -> Handle<NodeRef<BorrowType, K, V, marker::Leaf>, marker::Edge> {
match self.force() {
Leaf(leaf_kv) => leaf_kv.right_edge(),
Internal(internal_kv) => {
let next_internal_edge = internal_kv.right_edge();
next_internal_edge.descend().first_leaf_edge()
}
}
}
/// Returns the leaf edge closest to a KV for backward navigation.
pub fn next_back_leaf_edge(
self,
) -> Handle<NodeRef<BorrowType, K, V, marker::Leaf>, marker::Edge> {
match self.force() {
Leaf(leaf_kv) => leaf_kv.left_edge(),
Internal(internal_kv) => {
let next_internal_edge = internal_kv.left_edge();
next_internal_edge.descend().last_leaf_edge()
}
}
}
}
impl<BorrowType: marker::BorrowType, K, V> NodeRef<BorrowType, K, V, marker::LeafOrInternal> {
/// Returns the leaf edge corresponding to the first point at which the
/// given bound is true.
pub fn lower_bound<Q: ?Sized>(
self,
mut bound: SearchBound<&Q>,
) -> Handle<NodeRef<BorrowType, K, V, marker::Leaf>, marker::Edge>
where
Q: Ord,
K: Borrow<Q>,
{
let mut node = self;
loop {
let (edge, new_bound) = node.find_lower_bound_edge(bound);
match edge.force() {
Leaf(edge) => return edge,
Internal(edge) => {
node = edge.descend();
bound = new_bound;
}
}
}
}
/// Returns the leaf edge corresponding to the last point at which the
/// given bound is true.
pub fn upper_bound<Q: ?Sized>(
self,
mut bound: SearchBound<&Q>,
) -> Handle<NodeRef<BorrowType, K, V, marker::Leaf>, marker::Edge>
where
Q: Ord,
K: Borrow<Q>,
{
let mut node = self;
loop {
let (edge, new_bound) = node.find_upper_bound_edge(bound);
match edge.force() {
Leaf(edge) => return edge,
Internal(edge) => {
node = edge.descend();
bound = new_bound;
}
}
}
}
}