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node.rs
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node.rs
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// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
// This is an attempt at an implementation following the ideal
//
// ```
// struct BTreeMap<K, V> {
// height: usize,
// root: Option<Box<Node<K, V, height>>>
// }
//
// struct Node<K, V, height: usize> {
// keys: [K; 2 * T - 1],
// vals: [V; 2 * T - 1],
// edges: if height > 0 {
// [Box<Node<K, V, height - 1>>; 2 * T]
// } else { () },
// parent: *mut Node<K, V, height + 1>,
// parent_idx: u16,
// len: u16,
// }
// ```
//
// Since Rust doesn't acutally have dependent types and polymorphic recursion,
// we make do with lots of unsafety.
use alloc::heap;
use core::marker::PhantomData;
use core::mem;
use core::nonzero::NonZero;
use core::ptr::{self, Unique};
use core::slice;
use boxed::Box;
const T: usize = 6;
struct LeafNode<K, V> {
keys: [K; 2 * T - 1],
vals: [V; 2 * T - 1],
parent: *mut InternalNode<K, V>,
parent_idx: u16,
len: u16,
}
impl<K, V> LeafNode<K, V> {
unsafe fn new() -> Self {
LeafNode {
keys: mem::uninitialized(),
vals: mem::uninitialized(),
parent: ptr::null_mut(),
parent_idx: mem::uninitialized(),
len: 0
}
}
}
// We use repr(C) so that a pointer to an internal node can be
// directly used as a pointer to a leaf node
#[repr(C)]
struct InternalNode<K, V> {
data: LeafNode<K, V>,
edges: [BoxedNode<K, V>; 2 * T],
}
impl<K, V> InternalNode<K, V> {
unsafe fn new() -> Self {
InternalNode {
data: LeafNode::new(),
edges: mem::uninitialized()
}
}
}
struct BoxedNode<K, V> {
ptr: Unique<LeafNode<K, V>> // we don't know if this points to a leaf node or an internal node
}
impl<K, V> BoxedNode<K, V> {
fn from_leaf(node: Box<LeafNode<K, V>>) -> Self {
unsafe {
BoxedNode { ptr: Unique::new(Box::into_raw(node)) }
}
}
fn from_internal(node: Box<InternalNode<K, V>>) -> Self {
unsafe {
BoxedNode { ptr: Unique::new(Box::into_raw(node) as *mut LeafNode<K, V>) }
}
}
unsafe fn from_ptr(ptr: NonZero<*mut LeafNode<K, V>>) -> Self {
BoxedNode { ptr: Unique::new(*ptr) }
}
fn as_ptr(&self) -> NonZero<*mut LeafNode<K, V>> {
unsafe {
NonZero::new(*self.ptr)
}
}
}
/// An owned tree. Note that despite being owned, this does not have a destructor,
/// and must be cleaned up manually.
pub struct Root<K, V> {
node: BoxedNode<K, V>,
height: usize
}
unsafe impl<K: Sync, V: Sync> Sync for Root<K, V> { }
unsafe impl<K: Send, V: Send> Send for Root<K, V> { }
impl<K, V> Root<K, V> {
pub fn new_leaf() -> Self {
Root {
node: BoxedNode::from_leaf(Box::new(unsafe { LeafNode::new() })),
height: 0
}
}
pub fn as_ref(&self)
-> NodeRef<marker::Borrowed, K, V, marker::Immut, marker::LeafOrInternal> {
NodeRef {
height: self.height,
node: self.node.as_ptr(),
root: self as *const _ as *mut _,
_marker: PhantomData,
}
}
pub fn as_mut(&mut self)
-> NodeRef<marker::Borrowed, K, V, marker::Mut, marker::LeafOrInternal> {
NodeRef {
height: self.height,
node: self.node.as_ptr(),
root: self as *mut _,
_marker: PhantomData,
}
}
pub fn into_ref(self)
-> NodeRef<marker::Owned, K, V, marker::Mut, marker::LeafOrInternal> {
NodeRef {
height: self.height,
node: self.node.as_ptr(),
root: ptr::null_mut(), // FIXME: Is there anything better to do here?
_marker: PhantomData,
}
}
/// Add a new internal node with a single edge, pointing to the previous root, and make that
/// new node the root. This increases the height by 1 and is the opposite of `shrink`.
pub fn enlarge(&mut self)
-> NodeRef<marker::Borrowed, K, V, marker::Mut, marker::Internal> {
let mut new_node = Box::new(unsafe { InternalNode::new() });
new_node.edges[0] = unsafe { BoxedNode::from_ptr(self.node.as_ptr()) };
self.node = BoxedNode::from_internal(new_node);
self.height += 1;
let mut ret = NodeRef {
height: self.height,
node: self.node.as_ptr(),
root: self as *mut _,
_marker: PhantomData
};
unsafe {
ret.reborrow_mut().first_edge().correct_parent_link();
}
ret
}
/// Remove the root node, using its first child as the new root. This cannot be called when
/// the tree consists only of a leaf node. As it is intended only to be called when the root
/// has only one edge, no cleanup is done on any of the other children are elements of the root.
/// This decreases the height by 1 and is the opposite of `enlarge`.
pub fn shrink(&mut self) {
debug_assert!(self.height > 0);
let top = *self.node.ptr as *mut u8;
self.node = unsafe {
BoxedNode::from_ptr(self.as_mut()
.cast_unchecked::<marker::Internal>()
.first_edge()
.descend()
.node)
};
self.height -= 1;
self.as_mut().as_leaf_mut().parent = ptr::null_mut();
unsafe {
heap::deallocate(
top,
mem::size_of::<InternalNode<K, V>>(),
mem::align_of::<InternalNode<K, V>>()
);
}
}
}
/// A reference to a node.
///
/// This type has a number of paramaters that controls how it acts:
/// - `Lifetime`: This can either be `Borrowed<'a>` for some `'a` or `Owned`.
/// When it is `Borrowed<'a>`, the `NodeRef` acts roughly like `&'a Node`,
/// and when this is `Owned`, the `NodeRef` acts roughly like `Box<Node>`.
/// - `K` and `V`: These control what types of things are stored in the nodes.
/// - `Mutability`: This can either be `Immut` or `Mut`. When this is `Immut`,
/// the `NodeRef` acts roughly like `&`, and when this is `Mut`, the `NodeRef`
/// acts roughly like `&mut`.
/// - `Type`: This can be `Leaf`, `Internal`, or `LeafOrInternal`. When this is
/// `Leaf`, the `NodeRef` points to a leaf node, when this is `Internal` the
/// `NodeRef` points to an internal node, and when this is `LeafOrInternal` the
/// `NodeRef` could be pointing to either type of node.
pub struct NodeRef<Lifetime, K, V, Mutability, Type> {
height: usize,
node: NonZero<*mut LeafNode<K, V>>,
root: *mut Root<K, V>,
_marker: PhantomData<(Lifetime, Mutability, Type)>
}
impl<'a, K: 'a, V: 'a, Type> Copy for NodeRef<marker::Borrowed<'a>, K, V, marker::Immut, Type> { }
impl<'a, K: 'a, V: 'a, Type> Clone for NodeRef<marker::Borrowed<'a>, K, V, marker::Immut, Type> {
fn clone(&self) -> Self {
*self
}
}
unsafe impl<Lifetime, K: Sync, V: Sync, Mutability, Type> Sync
for NodeRef<Lifetime, K, V, Mutability, Type> { }
unsafe impl<'a, K: Sync + 'a, V: Sync + 'a, Type> Send
for NodeRef<marker::Borrowed<'a>, K, V, marker::Immut, Type> { }
unsafe impl<'a, K: Send + 'a, V: Send + 'a, Type> Send
for NodeRef<marker::Borrowed<'a>, K, V, marker::Mut, Type> { }
unsafe impl<K: Send, V: Send, Mutability, Type> Send
for NodeRef<marker::Owned, K, V, Mutability, Type> { }
impl<Lifetime, K, V, Mutability> NodeRef<Lifetime, K, V, Mutability, marker::Internal> {
fn as_internal(&self) -> &InternalNode<K, V> {
unsafe {
&*(*self.node as *const InternalNode<K, V>)
}
}
}
impl<Lifetime, K, V> NodeRef<Lifetime, K, V, marker::Mut, marker::Internal> {
fn as_internal_mut(&mut self) -> &mut InternalNode<K, V> {
unsafe {
&mut *(*self.node as *mut InternalNode<K, V>)
}
}
}
impl<Lifetime, K, V, Mutability, Type> NodeRef<Lifetime, K, V, Mutability, Type> {
pub fn height(&self) -> usize {
self.height
}
#[cfg(test)]
pub fn parent_idx(&self) -> usize {
self.as_leaf().parent_idx as usize
}
pub fn len(&self) -> usize {
self.as_leaf().len as usize
}
pub fn capacity(&self) -> usize {
2 * T - 1
}
pub fn forget_type(self) -> NodeRef<Lifetime, K, V, Mutability, marker::LeafOrInternal> {
NodeRef {
height: self.height,
node: self.node,
root: self.root,
_marker: PhantomData
}
}
fn reborrow<'a>(&'a self) -> NodeRef<marker::Borrowed<'a>, K, V, marker::Immut, Type> {
NodeRef {
height: self.height,
node: self.node,
root: self.root,
_marker: PhantomData
}
}
fn as_leaf(&self) -> &LeafNode<K, V> {
unsafe {
&**self.node
}
}
pub fn keys(&self) -> &[K] {
self.reborrow().into_slices().0
}
pub fn vals(&self) -> &[V] {
self.reborrow().into_slices().1
}
pub fn ascend(self) -> Result<
Handle<
NodeRef<
Lifetime,
K, V,
Mutability,
marker::Internal
>,
marker::Edge
>,
Self
> {
if self.as_leaf().parent.is_null() {
Err(self)
} else {
Ok(Handle {
node: NodeRef {
height: self.height + 1,
node: unsafe {
NonZero::new(self.as_leaf().parent as *mut LeafNode<K, V>)
},
root: self.root,
_marker: PhantomData
},
idx: self.as_leaf().parent_idx as usize,
_marker: PhantomData
})
}
}
pub fn first_edge(self) -> Handle<Self, marker::Edge> {
unsafe { Handle::new(self, 0) }
}
pub fn last_edge(self) -> Handle<Self, marker::Edge> {
let len = self.len();
unsafe { Handle::new(self, len) }
}
}
impl<K, V> NodeRef<marker::Owned, K, V, marker::Mut, marker::Leaf> {
pub unsafe fn deallocate_and_ascend(mut self) -> Option<
Handle<
NodeRef<
marker::Owned,
K, V,
marker::Mut,
marker::Internal
>,
marker::Edge
>
> {
let ptr = self.as_leaf_mut() as *mut LeafNode<K, V> as *mut u8;
let ret = self.ascend().ok();
heap::deallocate(ptr, mem::size_of::<LeafNode<K, V>>(), mem::align_of::<LeafNode<K, V>>());
ret
}
}
impl<K, V> NodeRef<marker::Owned, K, V, marker::Mut, marker::Internal> {
pub unsafe fn deallocate_and_ascend(mut self) -> Option<
Handle<
NodeRef<
marker::Owned,
K, V,
marker::Mut,
marker::Internal
>,
marker::Edge
>
> {
let ptr = self.as_internal_mut() as *mut InternalNode<K, V> as *mut u8;
let ret = self.ascend().ok();
heap::deallocate(
ptr,
mem::size_of::<InternalNode<K, V>>(),
mem::align_of::<InternalNode<K, V>>()
);
ret
}
}
impl<Lifetime, K, V, Type> NodeRef<Lifetime, K, V, marker::Mut, Type> {
unsafe fn cast_unchecked<NewType>(&mut self)
-> NodeRef<marker::Borrowed, K, V, marker::Mut, NewType> {
NodeRef {
height: self.height,
node: self.node,
root: self.root,
_marker: PhantomData
}
}
unsafe fn reborrow_mut(&mut self) -> NodeRef<marker::Borrowed, K, V, marker::Mut, Type> {
NodeRef {
height: self.height,
node: self.node,
root: self.root,
_marker: PhantomData
}
}
fn as_leaf_mut(&mut self) -> &mut LeafNode<K, V> {
unsafe {
&mut **self.node
}
}
pub fn keys_mut(&mut self) -> &mut [K] {
unsafe { self.reborrow_mut().into_slices_mut().0 }
}
pub fn vals_mut(&mut self) -> &mut [V] {
unsafe { self.reborrow_mut().into_slices_mut().1 }
}
}
impl<'a, K: 'a, V: 'a, Mutability, Type> NodeRef<marker::Borrowed<'a>, K, V, Mutability, Type> {
pub fn into_slices(self) -> (&'a [K], &'a [V]) {
unsafe {
(
slice::from_raw_parts(
self.as_leaf().keys.as_ptr(),
self.len()
),
slice::from_raw_parts(
self.as_leaf().vals.as_ptr(),
self.len()
)
)
}
}
}
impl<'a, K: 'a, V: 'a, Type> NodeRef<marker::Borrowed<'a>, K, V, marker::Mut, Type> {
pub fn into_root_mut(self) -> &'a mut Root<K, V> {
unsafe {
&mut *self.root
}
}
pub fn into_slices_mut(mut self) -> (&'a mut [K], &'a mut [V]) {
unsafe {
(
slice::from_raw_parts_mut(
&mut self.as_leaf_mut().keys as *mut [K] as *mut K,
self.len()
),
slice::from_raw_parts_mut(
&mut self.as_leaf_mut().vals as *mut [V] as *mut V,
self.len()
)
)
}
}
}
impl<Lifetime, K, V> NodeRef<Lifetime, K, V, marker::Mut, marker::Leaf> {
pub fn push(&mut self, key: K, val: V) {
// Necessary for correctness, but this is an internal module
debug_assert!(self.len() < self.capacity());
let idx = self.len();
unsafe {
ptr::write(self.keys_mut().get_unchecked_mut(idx), key);
ptr::write(self.vals_mut().get_unchecked_mut(idx), val);
}
self.as_leaf_mut().len += 1;
}
pub fn push_front(&mut self, key: K, val: V) {
// Necessary for correctness, but this is an internal module
debug_assert!(self.len() < self.capacity());
unsafe {
slice_insert(self.keys_mut(), 0, key);
slice_insert(self.vals_mut(), 0, val);
}
self.as_leaf_mut().len += 1;
}
}
impl<Lifetime, K, V> NodeRef<Lifetime, K, V, marker::Mut, marker::Internal> {
pub fn push(&mut self, key: K, val: V, edge: Root<K, V>) {
// Necessary for correctness, but this is an internal module
debug_assert!(edge.height == self.height - 1);
debug_assert!(self.len() < self.capacity());
let idx = self.len();
unsafe {
ptr::write(self.keys_mut().get_unchecked_mut(idx), key);
ptr::write(self.vals_mut().get_unchecked_mut(idx), val);
ptr::write(self.as_internal_mut().edges.get_unchecked_mut(idx + 1), edge.node);
Handle::new(self.reborrow_mut(), idx + 1).correct_parent_link();
}
self.as_leaf_mut().len += 1;
}
pub fn push_front(&mut self, key: K, val: V, edge: Root<K, V>) {
// Necessary for correctness, but this is an internal module
debug_assert!(edge.height == self.height - 1);
debug_assert!(self.len() < self.capacity());
unsafe {
slice_insert(self.keys_mut(), 0, key);
slice_insert(self.vals_mut(), 0, val);
slice_insert(
slice::from_raw_parts_mut(
self.as_internal_mut().edges.as_mut_ptr(),
self.len()+1
),
0,
edge.node
);
self.as_leaf_mut().len += 1;
for i in 0..self.len()+1 {
Handle::new(self.reborrow_mut(), i).correct_parent_link();
}
}
}
}
impl<Lifetime, K, V> NodeRef<Lifetime, K, V, marker::Mut, marker::LeafOrInternal> {
pub fn pop(&mut self) -> (K, V, Option<Root<K, V>>) {
// Necessary for correctness, but this is an internal module
debug_assert!(self.len() > self.capacity()/2);
let idx = self.len() - 1;
unsafe {
let key = ptr::read(self.keys().get_unchecked(idx));
let val = ptr::read(self.vals().get_unchecked(idx));
let edge = match self.reborrow_mut().force() {
ForceResult::Leaf(_) => None,
ForceResult::Internal(internal) => {
let edge = ptr::read(internal.as_internal().edges.get_unchecked(idx + 1));
let mut new_root = Root { node: edge, height: internal.height - 1 };
new_root.as_mut().as_leaf_mut().parent = ptr::null_mut();
Some(new_root)
}
};
self.as_leaf_mut().len -= 1;
(key, val, edge)
}
}
pub fn pop_front(&mut self) -> (K, V, Option<Root<K, V>>) {
// Necessary for correctness, but this is an internal module
debug_assert!(self.len() > self.capacity()/2);
let old_len = self.len();
unsafe {
let key = slice_remove(self.keys_mut(), 0);
let val = slice_remove(self.vals_mut(), 0);
let edge = match self.reborrow_mut().force() {
ForceResult::Leaf(_) => None,
ForceResult::Internal(mut internal) => {
let edge = slice_remove(
slice::from_raw_parts_mut(
internal.as_internal_mut().edges.as_mut_ptr(),
old_len+1
),
0
);
let mut new_root = Root { node: edge, height: internal.height - 1 };
new_root.as_mut().as_leaf_mut().parent = ptr::null_mut();
for i in 0..old_len {
Handle::new(internal.reborrow_mut(), i).correct_parent_link();
}
Some(new_root)
}
};
self.as_leaf_mut().len -= 1;
(key, val, edge)
}
}
}
impl<Lifetime, K, V, Mutability> NodeRef<Lifetime, K, V, Mutability, marker::LeafOrInternal> {
pub fn force(self) -> ForceResult<
NodeRef<Lifetime, K, V, Mutability, marker::Leaf>,
NodeRef<Lifetime, K, V, Mutability, marker::Internal>
> {
if self.height == 0 {
ForceResult::Leaf(NodeRef {
height: self.height,
node: self.node,
root: self.root,
_marker: PhantomData
})
} else {
ForceResult::Internal(NodeRef {
height: self.height,
node: self.node,
root: self.root,
_marker: PhantomData
})
}
}
}
pub struct Handle<Node, Type> {
node: Node,
idx: usize,
_marker: PhantomData<Type>
}
impl<Node: Copy, Type> Copy for Handle<Node, Type> { }
impl<Node: Copy, Type> Clone for Handle<Node, Type> {
fn clone(&self) -> Self {
*self
}
}
impl<Node, Type> Handle<Node, Type> {
pub unsafe fn new(node: Node, idx: usize) -> Self {
Handle {
node: node,
idx: idx,
_marker: PhantomData
}
}
pub fn into_node(self) -> Node {
self.node
}
}
impl<Node> Handle<Node, marker::KV> {
pub fn left_edge(self) -> Handle<Node, marker::Edge> {
unsafe { Handle::new(self.node, self.idx) }
}
pub fn right_edge(self) -> Handle<Node, marker::Edge> {
unsafe { Handle::new(self.node, self.idx + 1) }
}
}
impl<Lifetime, K, V, Mutability, NodeType, HandleType> PartialEq
for Handle<NodeRef<Lifetime, K, V, Mutability, NodeType>, HandleType> {
fn eq(&self, other: &Self) -> bool {
self.node.node == other.node.node && self.idx == other.idx
}
}
impl<Lifetime, K, V, Mutability, NodeType, HandleType>
Handle<NodeRef<Lifetime, K, V, Mutability, NodeType>, HandleType> {
pub fn reborrow(&self)
-> Handle<NodeRef<marker::Borrowed, K, V, marker::Immut, NodeType>, HandleType> {
unsafe { Handle::new(self.node.reborrow(), self.idx) }
}
}
impl<Lifetime, K, V, NodeType, HandleType>
Handle<NodeRef<Lifetime, K, V, marker::Mut, NodeType>, HandleType> {
pub unsafe fn reborrow_mut(&mut self)
-> Handle<NodeRef<marker::Borrowed, K, V, marker::Mut, NodeType>, HandleType> {
Handle::new(self.node.reborrow_mut(), self.idx)
}
}
impl<Lifetime, K, V, Mutability, NodeType>
Handle<NodeRef<Lifetime, K, V, Mutability, NodeType>, marker::Edge> {
pub fn left_kv(self)
-> Result<Handle<NodeRef<Lifetime, K, V, Mutability, NodeType>, marker::KV>, Self> {
if self.idx > 0 {
unsafe {
Ok(Handle::new(self.node, self.idx - 1))
}
} else {
Err(self)
}
}
pub fn right_kv(self)
-> Result<Handle<NodeRef<Lifetime, K, V, Mutability, NodeType>, marker::KV>, Self> {
if self.idx < self.node.len() {
unsafe {
Ok(Handle::new(self.node, self.idx))
}
} else {
Err(self)
}
}
}
impl<Lifetime, K, V> Handle<NodeRef<Lifetime, K, V, marker::Mut, marker::Leaf>, marker::Edge> {
unsafe fn insert_unchecked(&mut self, key: K, val: V) -> *mut V {
slice_insert(self.node.keys_mut(), self.idx, key);
slice_insert(self.node.vals_mut(), self.idx, val);
self.node.as_leaf_mut().len += 1;
self.node.vals_mut().get_unchecked_mut(self.idx)
}
pub fn insert(mut self, key: K, val: V)
-> (InsertResult<Lifetime, K, V, marker::Leaf>, *mut V) {
if self.node.len() < self.node.capacity() {
unsafe {
let ptr = self.insert_unchecked(key, val);
(InsertResult::Fit(Handle::new(self.node, self.idx)), ptr)
}
} else {
let middle = unsafe { Handle::new(self.node, T) };
let (mut left, k, v, mut right) = middle.split();
let ptr = if self.idx <= T {
unsafe {
Handle::new(left.reborrow_mut(), self.idx).insert_unchecked(key, val)
}
} else {
unsafe {
Handle::new(
right.as_mut().cast_unchecked::<marker::Leaf>(),
self.idx - T - 1
).insert_unchecked(key, val)
}
};
(InsertResult::Split(left, k, v, right), ptr)
}
}
}
impl<Lifetime, K, V> Handle<NodeRef<Lifetime, K, V, marker::Mut, marker::Internal>, marker::Edge> {
fn correct_parent_link(mut self) {
let idx = self.idx as u16;
let ptr = self.node.as_internal_mut() as *mut _;
let mut child = self.descend();
child.as_leaf_mut().parent = ptr;
child.as_leaf_mut().parent_idx = idx;
}
unsafe fn cast_unchecked<NewType>(&mut self)
-> Handle<NodeRef<marker::Borrowed, K, V, marker::Mut, NewType>, marker::Edge> {
Handle::new(self.node.cast_unchecked(), self.idx)
}
unsafe fn insert_unchecked(&mut self, key: K, val: V, edge: Root<K, V>) {
self.cast_unchecked::<marker::Leaf>().insert_unchecked(key, val);
slice_insert(
slice::from_raw_parts_mut(
self.node.as_internal_mut().edges.as_mut_ptr(),
self.node.len()
),
self.idx + 1,
edge.node
);
for i in (self.idx+1)..(self.node.len()+1) {
Handle::new(self.node.reborrow_mut(), i).correct_parent_link();
}
}
pub fn insert(mut self, key: K, val: V, edge: Root<K, V>)
-> InsertResult<Lifetime, K, V, marker::Internal> {
// Necessary for correctness, but this is an internal module
debug_assert!(edge.height == self.node.height - 1);
if self.node.len() < self.node.capacity() {
unsafe {
self.insert_unchecked(key, val, edge);
InsertResult::Fit(Handle::new(self.node, self.idx))
}
} else {
let middle = unsafe { Handle::new(self.node, T) };
let (mut left, k, v, mut right) = middle.split();
if self.idx <= T {
unsafe {
Handle::new(left.reborrow_mut(), self.idx).insert_unchecked(key, val, edge);
}
} else {
unsafe {
Handle::new(
right.as_mut().cast_unchecked::<marker::Internal>(),
self.idx - T - 1
).insert_unchecked(key, val, edge);
}
}
InsertResult::Split(left, k, v, right)
}
}
}
impl<Lifetime, K, V, Mutability>
Handle<NodeRef<Lifetime, K, V, Mutability, marker::Internal>, marker::Edge> {
pub fn descend(self) -> NodeRef<Lifetime, K, V, Mutability, marker::LeafOrInternal> {
NodeRef {
height: self.node.height - 1,
node: unsafe { self.node.as_internal().edges.get_unchecked(self.idx).as_ptr() },
root: self.node.root,
_marker: PhantomData
}
}
}
impl<'a, K: 'a, V: 'a, Mutability, NodeType>
Handle<NodeRef<marker::Borrowed<'a>, K, V, Mutability, NodeType>, marker::KV> {
pub fn into_kv(self) -> (&'a K, &'a V) {
let (keys, vals) = self.node.into_slices();
unsafe {
(keys.get_unchecked(self.idx), vals.get_unchecked(self.idx))
}
}
}
impl<'a, K: 'a, V: 'a, NodeType>
Handle<NodeRef<marker::Borrowed<'a>, K, V, marker::Mut, NodeType>, marker::KV> {
pub fn into_kv_mut(self) -> (&'a mut K, &'a mut V) {
let (mut keys, mut vals) = self.node.into_slices_mut();
unsafe {
(keys.get_unchecked_mut(self.idx), vals.get_unchecked_mut(self.idx))
}
}
}
impl<Lifetime, K, V, NodeType> Handle<NodeRef<Lifetime, K, V, marker::Mut, NodeType>, marker::KV> {
pub fn kv_mut(&mut self) -> (&mut K, &mut V) {
unsafe {
let (mut keys, mut vals) = self.node.reborrow_mut().into_slices_mut();
(keys.get_unchecked_mut(self.idx), vals.get_unchecked_mut(self.idx))
}
}
}
impl<Lifetime, K, V> Handle<NodeRef<Lifetime, K, V, marker::Mut, marker::Leaf>, marker::KV> {
pub fn split(mut self)
-> (NodeRef<Lifetime, K, V, marker::Mut, marker::Leaf>, K, V, Root<K, V>) {
unsafe {
let mut new_node = Box::new(LeafNode::new());
let k = ptr::read(self.node.keys().get_unchecked(self.idx));
let v = ptr::read(self.node.vals().get_unchecked(self.idx));
let new_len = self.node.len() - self.idx - 1;
ptr::copy_nonoverlapping(
self.node.keys().as_ptr().offset(self.idx as isize + 1),
new_node.keys.as_mut_ptr(),
new_len
);
ptr::copy_nonoverlapping(
self.node.vals().as_ptr().offset(self.idx as isize + 1),
new_node.vals.as_mut_ptr(),
new_len
);
self.node.as_leaf_mut().len = self.idx as u16;
new_node.len = new_len as u16;
(
self.node,
k, v,
Root {
node: BoxedNode::from_leaf(new_node),
height: 0
}
)
}
}
pub fn remove(mut self)
-> (Handle<NodeRef<Lifetime, K, V, marker::Mut, marker::Leaf>, marker::Edge>, K, V) {
unsafe {
let k = slice_remove(self.node.keys_mut(), self.idx);
let v = slice_remove(self.node.vals_mut(), self.idx);
self.node.as_leaf_mut().len -= 1;
(self.left_edge(), k, v)
}
}
}
impl<Lifetime, K, V> Handle<NodeRef<Lifetime, K, V, marker::Mut, marker::Internal>, marker::KV> {
pub fn split(mut self)
-> (NodeRef<Lifetime, K, V, marker::Mut, marker::Internal>, K, V, Root<K, V>) {
unsafe {
let mut new_node = Box::new(InternalNode::new());
let k = ptr::read(self.node.keys().get_unchecked(self.idx));
let v = ptr::read(self.node.vals().get_unchecked(self.idx));
let height = self.node.height;
let new_len = self.node.len() - self.idx - 1;
ptr::copy_nonoverlapping(
self.node.keys().as_ptr().offset(self.idx as isize + 1),
new_node.data.keys.as_mut_ptr(),
new_len
);
ptr::copy_nonoverlapping(
self.node.vals().as_ptr().offset(self.idx as isize + 1),
new_node.data.vals.as_mut_ptr(),
new_len
);
ptr::copy_nonoverlapping(
self.node.as_internal().edges.as_ptr().offset(self.idx as isize + 1),
new_node.edges.as_mut_ptr(),
new_len + 1
);
self.node.as_leaf_mut().len = self.idx as u16;
new_node.data.len = new_len as u16;
let mut new_root = Root {
node: BoxedNode::from_internal(new_node),
height: height
};
for i in 0..(new_len+1) {
Handle::new(new_root.as_mut().cast_unchecked(), i).correct_parent_link();
}
(
self.node,
k, v,
new_root
)
}
}
pub fn can_merge(&self) -> bool {
(
self.reborrow()
.left_edge()
.descend()
.len()
+ self.reborrow()
.right_edge()
.descend()
.len()
+ 1
) <= self.node.capacity()
}
pub fn merge(mut self)
-> Handle<NodeRef<Lifetime, K, V, marker::Mut, marker::Internal>, marker::Edge> {
let self1 = unsafe { ptr::read(&self) };
let self2 = unsafe { ptr::read(&self) };
let mut left_node = self1.left_edge().descend();
let left_len = left_node.len();
let mut right_node = self2.right_edge().descend();
let right_len = right_node.len();
// necessary for correctness, but in a private module
debug_assert!(left_len + right_len + 1 <= left_node.capacity());
unsafe {
*left_node.keys_mut().get_unchecked_mut(left_len)
= slice_remove(self.node.keys_mut(), self.idx);
ptr::copy_nonoverlapping(
right_node.keys().as_ptr(),
left_node.keys_mut().as_mut_ptr().offset(left_len as isize + 1),
right_len
);