Skip to content
Permalink
Branch: master
Find file Copy path
Find file Copy path
Fetching contributors…
Cannot retrieve contributors at this time
2615 lines (2375 sloc) 80.3 KB
use core::borrow::Borrow;
use core::cmp::Ordering;
use core::fmt::Debug;
use core::hash::{Hash, Hasher};
use core::iter::{FromIterator, Peekable, FusedIterator};
use core::marker::PhantomData;
use core::ops::Bound::{Excluded, Included, Unbounded};
use core::ops::{Index, RangeBounds};
use core::{fmt, intrinsics, mem, ptr};
use super::node::{self, Handle, NodeRef, marker, InsertResult::*, ForceResult::*};
use super::search::{self, SearchResult::*};
use UnderflowResult::*;
use Entry::*;
/// A map based on a B-Tree.
///
/// B-Trees represent a fundamental compromise between cache-efficiency and actually minimizing
/// the amount of work performed in a search. In theory, a binary search tree (BST) is the optimal
/// choice for a sorted map, as a perfectly balanced BST performs the theoretical minimum amount of
/// comparisons necessary to find an element (log<sub>2</sub>n). However, in practice the way this
/// is done is *very* inefficient for modern computer architectures. In particular, every element
/// is stored in its own individually heap-allocated node. This means that every single insertion
/// triggers a heap-allocation, and every single comparison should be a cache-miss. Since these
/// are both notably expensive things to do in practice, we are forced to at very least reconsider
/// the BST strategy.
///
/// A B-Tree instead makes each node contain B-1 to 2B-1 elements in a contiguous array. By doing
/// this, we reduce the number of allocations by a factor of B, and improve cache efficiency in
/// searches. However, this does mean that searches will have to do *more* comparisons on average.
/// The precise number of comparisons depends on the node search strategy used. For optimal cache
/// efficiency, one could search the nodes linearly. For optimal comparisons, one could search
/// the node using binary search. As a compromise, one could also perform a linear search
/// that initially only checks every i<sup>th</sup> element for some choice of i.
///
/// Currently, our implementation simply performs naive linear search. This provides excellent
/// performance on *small* nodes of elements which are cheap to compare. However in the future we
/// would like to further explore choosing the optimal search strategy based on the choice of B,
/// and possibly other factors. Using linear search, searching for a random element is expected
/// to take O(B log<sub>B</sub>n) comparisons, which is generally worse than a BST. In practice,
/// however, performance is excellent.
///
/// It is a logic error for a key to be modified in such a way that the key's ordering relative to
/// any other key, as determined by the [`Ord`] trait, changes while it is in the map. This is
/// normally only possible through [`Cell`], [`RefCell`], global state, I/O, or unsafe code.
///
/// [`Ord`]: ../../std/cmp/trait.Ord.html
/// [`Cell`]: ../../std/cell/struct.Cell.html
/// [`RefCell`]: ../../std/cell/struct.RefCell.html
///
/// # Examples
///
/// ```
/// use std::collections::BTreeMap;
///
/// // type inference lets us omit an explicit type signature (which
/// // would be `BTreeMap<&str, &str>` in this example).
/// let mut movie_reviews = BTreeMap::new();
///
/// // review some movies.
/// movie_reviews.insert("Office Space", "Deals with real issues in the workplace.");
/// movie_reviews.insert("Pulp Fiction", "Masterpiece.");
/// movie_reviews.insert("The Godfather", "Very enjoyable.");
/// movie_reviews.insert("The Blues Brothers", "Eye lyked it a lot.");
///
/// // check for a specific one.
/// if !movie_reviews.contains_key("Les Misérables") {
/// println!("We've got {} reviews, but Les Misérables ain't one.",
/// movie_reviews.len());
/// }
///
/// // oops, this review has a lot of spelling mistakes, let's delete it.
/// movie_reviews.remove("The Blues Brothers");
///
/// // look up the values associated with some keys.
/// let to_find = ["Up!", "Office Space"];
/// for movie in &to_find {
/// match movie_reviews.get(movie) {
/// Some(review) => println!("{}: {}", movie, review),
/// None => println!("{} is unreviewed.", movie)
/// }
/// }
///
/// // Look up the value for a key (will panic if the key is not found).
/// println!("Movie review: {}", movie_reviews["Office Space"]);
///
/// // iterate over everything.
/// for (movie, review) in &movie_reviews {
/// println!("{}: \"{}\"", movie, review);
/// }
/// ```
///
/// `BTreeMap` also implements an [`Entry API`](#method.entry), which allows
/// for more complex methods of getting, setting, updating and removing keys and
/// their values:
///
/// ```
/// use std::collections::BTreeMap;
///
/// // type inference lets us omit an explicit type signature (which
/// // would be `BTreeMap<&str, u8>` in this example).
/// let mut player_stats = BTreeMap::new();
///
/// fn random_stat_buff() -> u8 {
/// // could actually return some random value here - let's just return
/// // some fixed value for now
/// 42
/// }
///
/// // insert a key only if it doesn't already exist
/// player_stats.entry("health").or_insert(100);
///
/// // insert a key using a function that provides a new value only if it
/// // doesn't already exist
/// player_stats.entry("defence").or_insert_with(random_stat_buff);
///
/// // update a key, guarding against the key possibly not being set
/// let stat = player_stats.entry("attack").or_insert(100);
/// *stat += random_stat_buff();
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub struct BTreeMap<K, V> {
root: node::Root<K, V>,
length: usize,
}
#[stable(feature = "btree_drop", since = "1.7.0")]
unsafe impl<#[may_dangle] K, #[may_dangle] V> Drop for BTreeMap<K, V> {
fn drop(&mut self) {
unsafe {
drop(ptr::read(self).into_iter());
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K: Clone, V: Clone> Clone for BTreeMap<K, V> {
fn clone(&self) -> BTreeMap<K, V> {
fn clone_subtree<'a, K: Clone, V: Clone>(
node: node::NodeRef<marker::Immut<'a>, K, V, marker::LeafOrInternal>
) -> BTreeMap<K, V>
where K: 'a, V: 'a,
{
match node.force() {
Leaf(leaf) => {
let mut out_tree = BTreeMap {
root: node::Root::new_leaf(),
length: 0,
};
{
let mut out_node = match out_tree.root.as_mut().force() {
Leaf(leaf) => leaf,
Internal(_) => unreachable!(),
};
let mut in_edge = leaf.first_edge();
while let Ok(kv) = in_edge.right_kv() {
let (k, v) = kv.into_kv();
in_edge = kv.right_edge();
out_node.push(k.clone(), v.clone());
out_tree.length += 1;
}
}
out_tree
}
Internal(internal) => {
let mut out_tree = clone_subtree(internal.first_edge().descend());
{
let mut out_node = out_tree.root.push_level();
let mut in_edge = internal.first_edge();
while let Ok(kv) = in_edge.right_kv() {
let (k, v) = kv.into_kv();
in_edge = kv.right_edge();
let k = (*k).clone();
let v = (*v).clone();
let subtree = clone_subtree(in_edge.descend());
// We can't destructure subtree directly
// because BTreeMap implements Drop
let (subroot, sublength) = unsafe {
let root = ptr::read(&subtree.root);
let length = subtree.length;
mem::forget(subtree);
(root, length)
};
out_node.push(k, v, subroot);
out_tree.length += 1 + sublength;
}
}
out_tree
}
}
}
if self.len() == 0 {
// Ideally we'd call `BTreeMap::new` here, but that has the `K:
// Ord` constraint, which this method lacks.
BTreeMap {
root: node::Root::shared_empty_root(),
length: 0,
}
} else {
clone_subtree(self.root.as_ref())
}
}
}
impl<K, Q: ?Sized> super::Recover<Q> for BTreeMap<K, ()>
where K: Borrow<Q> + Ord,
Q: Ord
{
type Key = K;
fn get(&self, key: &Q) -> Option<&K> {
match search::search_tree(self.root.as_ref(), key) {
Found(handle) => Some(handle.into_kv().0),
GoDown(_) => None,
}
}
fn take(&mut self, key: &Q) -> Option<K> {
match search::search_tree(self.root.as_mut(), key) {
Found(handle) => {
Some(OccupiedEntry {
handle,
length: &mut self.length,
_marker: PhantomData,
}
.remove_kv()
.0)
}
GoDown(_) => None,
}
}
fn replace(&mut self, key: K) -> Option<K> {
self.ensure_root_is_owned();
match search::search_tree::<marker::Mut<'_>, K, (), K>(self.root.as_mut(), &key) {
Found(handle) => Some(mem::replace(handle.into_kv_mut().0, key)),
GoDown(handle) => {
VacantEntry {
key,
handle,
length: &mut self.length,
_marker: PhantomData,
}
.insert(());
None
}
}
}
}
/// An iterator over the entries of a `BTreeMap`.
///
/// This `struct` is created by the [`iter`] method on [`BTreeMap`]. See its
/// documentation for more.
///
/// [`iter`]: struct.BTreeMap.html#method.iter
/// [`BTreeMap`]: struct.BTreeMap.html
#[stable(feature = "rust1", since = "1.0.0")]
pub struct Iter<'a, K: 'a, V: 'a> {
range: Range<'a, K, V>,
length: usize,
}
#[stable(feature = "collection_debug", since = "1.17.0")]
impl<K: fmt::Debug, V: fmt::Debug> fmt::Debug for Iter<'_, K, V> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_list().entries(self.clone()).finish()
}
}
/// A mutable iterator over the entries of a `BTreeMap`.
///
/// This `struct` is created by the [`iter_mut`] method on [`BTreeMap`]. See its
/// documentation for more.
///
/// [`iter_mut`]: struct.BTreeMap.html#method.iter_mut
/// [`BTreeMap`]: struct.BTreeMap.html
#[stable(feature = "rust1", since = "1.0.0")]
#[derive(Debug)]
pub struct IterMut<'a, K: 'a, V: 'a> {
range: RangeMut<'a, K, V>,
length: usize,
}
/// An owning iterator over the entries of a `BTreeMap`.
///
/// This `struct` is created by the [`into_iter`] method on [`BTreeMap`][`BTreeMap`]
/// (provided by the `IntoIterator` trait). See its documentation for more.
///
/// [`into_iter`]: struct.BTreeMap.html#method.into_iter
/// [`BTreeMap`]: struct.BTreeMap.html
#[stable(feature = "rust1", since = "1.0.0")]
pub struct IntoIter<K, V> {
front: Handle<NodeRef<marker::Owned, K, V, marker::Leaf>, marker::Edge>,
back: Handle<NodeRef<marker::Owned, K, V, marker::Leaf>, marker::Edge>,
length: usize,
}
#[stable(feature = "collection_debug", since = "1.17.0")]
impl<K: fmt::Debug, V: fmt::Debug> fmt::Debug for IntoIter<K, V> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let range = Range {
front: self.front.reborrow(),
back: self.back.reborrow(),
};
f.debug_list().entries(range).finish()
}
}
/// An iterator over the keys of a `BTreeMap`.
///
/// This `struct` is created by the [`keys`] method on [`BTreeMap`]. See its
/// documentation for more.
///
/// [`keys`]: struct.BTreeMap.html#method.keys
/// [`BTreeMap`]: struct.BTreeMap.html
#[stable(feature = "rust1", since = "1.0.0")]
pub struct Keys<'a, K: 'a, V: 'a> {
inner: Iter<'a, K, V>,
}
#[stable(feature = "collection_debug", since = "1.17.0")]
impl<K: fmt::Debug, V> fmt::Debug for Keys<'_, K, V> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_list().entries(self.clone()).finish()
}
}
/// An iterator over the values of a `BTreeMap`.
///
/// This `struct` is created by the [`values`] method on [`BTreeMap`]. See its
/// documentation for more.
///
/// [`values`]: struct.BTreeMap.html#method.values
/// [`BTreeMap`]: struct.BTreeMap.html
#[stable(feature = "rust1", since = "1.0.0")]
pub struct Values<'a, K: 'a, V: 'a> {
inner: Iter<'a, K, V>,
}
#[stable(feature = "collection_debug", since = "1.17.0")]
impl<K, V: fmt::Debug> fmt::Debug for Values<'_, K, V> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_list().entries(self.clone()).finish()
}
}
/// A mutable iterator over the values of a `BTreeMap`.
///
/// This `struct` is created by the [`values_mut`] method on [`BTreeMap`]. See its
/// documentation for more.
///
/// [`values_mut`]: struct.BTreeMap.html#method.values_mut
/// [`BTreeMap`]: struct.BTreeMap.html
#[stable(feature = "map_values_mut", since = "1.10.0")]
#[derive(Debug)]
pub struct ValuesMut<'a, K: 'a, V: 'a> {
inner: IterMut<'a, K, V>,
}
/// An iterator over a sub-range of entries in a `BTreeMap`.
///
/// This `struct` is created by the [`range`] method on [`BTreeMap`]. See its
/// documentation for more.
///
/// [`range`]: struct.BTreeMap.html#method.range
/// [`BTreeMap`]: struct.BTreeMap.html
#[stable(feature = "btree_range", since = "1.17.0")]
pub struct Range<'a, K: 'a, V: 'a> {
front: Handle<NodeRef<marker::Immut<'a>, K, V, marker::Leaf>, marker::Edge>,
back: Handle<NodeRef<marker::Immut<'a>, K, V, marker::Leaf>, marker::Edge>,
}
#[stable(feature = "collection_debug", since = "1.17.0")]
impl<K: fmt::Debug, V: fmt::Debug> fmt::Debug for Range<'_, K, V> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_list().entries(self.clone()).finish()
}
}
/// A mutable iterator over a sub-range of entries in a `BTreeMap`.
///
/// This `struct` is created by the [`range_mut`] method on [`BTreeMap`]. See its
/// documentation for more.
///
/// [`range_mut`]: struct.BTreeMap.html#method.range_mut
/// [`BTreeMap`]: struct.BTreeMap.html
#[stable(feature = "btree_range", since = "1.17.0")]
pub struct RangeMut<'a, K: 'a, V: 'a> {
front: Handle<NodeRef<marker::Mut<'a>, K, V, marker::Leaf>, marker::Edge>,
back: Handle<NodeRef<marker::Mut<'a>, K, V, marker::Leaf>, marker::Edge>,
// Be invariant in `K` and `V`
_marker: PhantomData<&'a mut (K, V)>,
}
#[stable(feature = "collection_debug", since = "1.17.0")]
impl<K: fmt::Debug, V: fmt::Debug> fmt::Debug for RangeMut<'_, K, V> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let range = Range {
front: self.front.reborrow(),
back: self.back.reborrow(),
};
f.debug_list().entries(range).finish()
}
}
/// A view into a single entry in a map, which may either be vacant or occupied.
///
/// This `enum` is constructed from the [`entry`] method on [`BTreeMap`].
///
/// [`BTreeMap`]: struct.BTreeMap.html
/// [`entry`]: struct.BTreeMap.html#method.entry
#[stable(feature = "rust1", since = "1.0.0")]
pub enum Entry<'a, K: 'a, V: 'a> {
/// A vacant entry.
#[stable(feature = "rust1", since = "1.0.0")]
Vacant(#[stable(feature = "rust1", since = "1.0.0")]
VacantEntry<'a, K, V>),
/// An occupied entry.
#[stable(feature = "rust1", since = "1.0.0")]
Occupied(#[stable(feature = "rust1", since = "1.0.0")]
OccupiedEntry<'a, K, V>),
}
#[stable(feature= "debug_btree_map", since = "1.12.0")]
impl<K: Debug + Ord, V: Debug> Debug for Entry<'_, K, V> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match *self {
Vacant(ref v) => f.debug_tuple("Entry")
.field(v)
.finish(),
Occupied(ref o) => f.debug_tuple("Entry")
.field(o)
.finish(),
}
}
}
/// A view into a vacant entry in a `BTreeMap`.
/// It is part of the [`Entry`] enum.
///
/// [`Entry`]: enum.Entry.html
#[stable(feature = "rust1", since = "1.0.0")]
pub struct VacantEntry<'a, K: 'a, V: 'a> {
key: K,
handle: Handle<NodeRef<marker::Mut<'a>, K, V, marker::Leaf>, marker::Edge>,
length: &'a mut usize,
// Be invariant in `K` and `V`
_marker: PhantomData<&'a mut (K, V)>,
}
#[stable(feature= "debug_btree_map", since = "1.12.0")]
impl<K: Debug + Ord, V> Debug for VacantEntry<'_, K, V> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_tuple("VacantEntry")
.field(self.key())
.finish()
}
}
/// A view into an occupied entry in a `BTreeMap`.
/// It is part of the [`Entry`] enum.
///
/// [`Entry`]: enum.Entry.html
#[stable(feature = "rust1", since = "1.0.0")]
pub struct OccupiedEntry<'a, K: 'a, V: 'a> {
handle: Handle<NodeRef<marker::Mut<'a>, K, V, marker::LeafOrInternal>, marker::KV>,
length: &'a mut usize,
// Be invariant in `K` and `V`
_marker: PhantomData<&'a mut (K, V)>,
}
#[stable(feature= "debug_btree_map", since = "1.12.0")]
impl<K: Debug + Ord, V: Debug> Debug for OccupiedEntry<'_, K, V> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("OccupiedEntry")
.field("key", self.key())
.field("value", self.get())
.finish()
}
}
// An iterator for merging two sorted sequences into one
struct MergeIter<K, V, I: Iterator<Item = (K, V)>> {
left: Peekable<I>,
right: Peekable<I>,
}
impl<K: Ord, V> BTreeMap<K, V> {
/// Makes a new empty BTreeMap with a reasonable choice for B.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use std::collections::BTreeMap;
///
/// let mut map = BTreeMap::new();
///
/// // entries can now be inserted into the empty map
/// map.insert(1, "a");
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn new() -> BTreeMap<K, V> {
BTreeMap {
root: node::Root::shared_empty_root(),
length: 0,
}
}
/// Clears the map, removing all values.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use std::collections::BTreeMap;
///
/// let mut a = BTreeMap::new();
/// a.insert(1, "a");
/// a.clear();
/// assert!(a.is_empty());
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn clear(&mut self) {
*self = BTreeMap::new();
}
/// Returns a reference to the value corresponding to the key.
///
/// The key may be any borrowed form of the map's key type, but the ordering
/// on the borrowed form *must* match the ordering on the key type.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use std::collections::BTreeMap;
///
/// let mut map = BTreeMap::new();
/// map.insert(1, "a");
/// assert_eq!(map.get(&1), Some(&"a"));
/// assert_eq!(map.get(&2), None);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn get<Q: ?Sized>(&self, key: &Q) -> Option<&V>
where K: Borrow<Q>,
Q: Ord
{
match search::search_tree(self.root.as_ref(), key) {
Found(handle) => Some(handle.into_kv().1),
GoDown(_) => None,
}
}
/// Returns the key-value pair corresponding to the supplied key.
///
/// The supplied key may be any borrowed form of the map's key type, but the ordering
/// on the borrowed form *must* match the ordering on the key type.
///
/// # Examples
///
/// ```
/// #![feature(map_get_key_value)]
/// use std::collections::BTreeMap;
///
/// let mut map = BTreeMap::new();
/// map.insert(1, "a");
/// assert_eq!(map.get_key_value(&1), Some((&1, &"a")));
/// assert_eq!(map.get_key_value(&2), None);
/// ```
#[unstable(feature = "map_get_key_value", issue = "49347")]
pub fn get_key_value<Q: ?Sized>(&self, k: &Q) -> Option<(&K, &V)>
where K: Borrow<Q>,
Q: Ord
{
match search::search_tree(self.root.as_ref(), k) {
Found(handle) => Some(handle.into_kv()),
GoDown(_) => None,
}
}
/// Returns `true` if the map contains a value for the specified key.
///
/// The key may be any borrowed form of the map's key type, but the ordering
/// on the borrowed form *must* match the ordering on the key type.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use std::collections::BTreeMap;
///
/// let mut map = BTreeMap::new();
/// map.insert(1, "a");
/// assert_eq!(map.contains_key(&1), true);
/// assert_eq!(map.contains_key(&2), false);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn contains_key<Q: ?Sized>(&self, key: &Q) -> bool
where K: Borrow<Q>,
Q: Ord
{
self.get(key).is_some()
}
/// Returns a mutable reference to the value corresponding to the key.
///
/// The key may be any borrowed form of the map's key type, but the ordering
/// on the borrowed form *must* match the ordering on the key type.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use std::collections::BTreeMap;
///
/// let mut map = BTreeMap::new();
/// map.insert(1, "a");
/// if let Some(x) = map.get_mut(&1) {
/// *x = "b";
/// }
/// assert_eq!(map[&1], "b");
/// ```
// See `get` for implementation notes, this is basically a copy-paste with mut's added
#[stable(feature = "rust1", since = "1.0.0")]
pub fn get_mut<Q: ?Sized>(&mut self, key: &Q) -> Option<&mut V>
where K: Borrow<Q>,
Q: Ord
{
match search::search_tree(self.root.as_mut(), key) {
Found(handle) => Some(handle.into_kv_mut().1),
GoDown(_) => None,
}
}
/// Inserts a key-value pair into the map.
///
/// If the map did not have this key present, `None` is returned.
///
/// If the map did have this key present, the value is updated, and the old
/// value is returned. The key is not updated, though; this matters for
/// types that can be `==` without being identical. See the [module-level
/// documentation] for more.
///
/// [module-level documentation]: index.html#insert-and-complex-keys
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use std::collections::BTreeMap;
///
/// let mut map = BTreeMap::new();
/// assert_eq!(map.insert(37, "a"), None);
/// assert_eq!(map.is_empty(), false);
///
/// map.insert(37, "b");
/// assert_eq!(map.insert(37, "c"), Some("b"));
/// assert_eq!(map[&37], "c");
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn insert(&mut self, key: K, value: V) -> Option<V> {
match self.entry(key) {
Occupied(mut entry) => Some(entry.insert(value)),
Vacant(entry) => {
entry.insert(value);
None
}
}
}
/// Removes a key from the map, returning the value at the key if the key
/// was previously in the map.
///
/// The key may be any borrowed form of the map's key type, but the ordering
/// on the borrowed form *must* match the ordering on the key type.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use std::collections::BTreeMap;
///
/// let mut map = BTreeMap::new();
/// map.insert(1, "a");
/// assert_eq!(map.remove(&1), Some("a"));
/// assert_eq!(map.remove(&1), None);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn remove<Q: ?Sized>(&mut self, key: &Q) -> Option<V>
where K: Borrow<Q>,
Q: Ord
{
match search::search_tree(self.root.as_mut(), key) {
Found(handle) => {
Some(OccupiedEntry {
handle,
length: &mut self.length,
_marker: PhantomData,
}
.remove())
}
GoDown(_) => None,
}
}
/// Moves all elements from `other` into `Self`, leaving `other` empty.
///
/// # Examples
///
/// ```
/// use std::collections::BTreeMap;
///
/// let mut a = BTreeMap::new();
/// a.insert(1, "a");
/// a.insert(2, "b");
/// a.insert(3, "c");
///
/// let mut b = BTreeMap::new();
/// b.insert(3, "d");
/// b.insert(4, "e");
/// b.insert(5, "f");
///
/// a.append(&mut b);
///
/// assert_eq!(a.len(), 5);
/// assert_eq!(b.len(), 0);
///
/// assert_eq!(a[&1], "a");
/// assert_eq!(a[&2], "b");
/// assert_eq!(a[&3], "d");
/// assert_eq!(a[&4], "e");
/// assert_eq!(a[&5], "f");
/// ```
#[stable(feature = "btree_append", since = "1.11.0")]
pub fn append(&mut self, other: &mut Self) {
// Do we have to append anything at all?
if other.len() == 0 {
return;
}
// We can just swap `self` and `other` if `self` is empty.
if self.len() == 0 {
mem::swap(self, other);
return;
}
// First, we merge `self` and `other` into a sorted sequence in linear time.
let self_iter = mem::take(self).into_iter();
let other_iter = mem::take(other).into_iter();
let iter = MergeIter {
left: self_iter.peekable(),
right: other_iter.peekable(),
};
// Second, we build a tree from the sorted sequence in linear time.
self.from_sorted_iter(iter);
self.fix_right_edge();
}
/// Constructs a double-ended iterator over a sub-range of elements in the map.
/// The simplest way is to use the range syntax `min..max`, thus `range(min..max)` will
/// yield elements from min (inclusive) to max (exclusive).
/// The range may also be entered as `(Bound<T>, Bound<T>)`, so for example
/// `range((Excluded(4), Included(10)))` will yield a left-exclusive, right-inclusive
/// range from 4 to 10.
///
/// # Panics
///
/// Panics if range `start > end`.
/// Panics if range `start == end` and both bounds are `Excluded`.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use std::collections::BTreeMap;
/// use std::ops::Bound::Included;
///
/// let mut map = BTreeMap::new();
/// map.insert(3, "a");
/// map.insert(5, "b");
/// map.insert(8, "c");
/// for (&key, &value) in map.range((Included(&4), Included(&8))) {
/// println!("{}: {}", key, value);
/// }
/// assert_eq!(Some((&5, &"b")), map.range(4..).next());
/// ```
#[stable(feature = "btree_range", since = "1.17.0")]
pub fn range<T: ?Sized, R>(&self, range: R) -> Range<'_, K, V>
where T: Ord, K: Borrow<T>, R: RangeBounds<T>
{
let root1 = self.root.as_ref();
let root2 = self.root.as_ref();
let (f, b) = range_search(root1, root2, range);
Range { front: f, back: b}
}
/// Constructs a mutable double-ended iterator over a sub-range of elements in the map.
/// The simplest way is to use the range syntax `min..max`, thus `range(min..max)` will
/// yield elements from min (inclusive) to max (exclusive).
/// The range may also be entered as `(Bound<T>, Bound<T>)`, so for example
/// `range((Excluded(4), Included(10)))` will yield a left-exclusive, right-inclusive
/// range from 4 to 10.
///
/// # Panics
///
/// Panics if range `start > end`.
/// Panics if range `start == end` and both bounds are `Excluded`.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use std::collections::BTreeMap;
///
/// let mut map: BTreeMap<&str, i32> = ["Alice", "Bob", "Carol", "Cheryl"]
/// .iter()
/// .map(|&s| (s, 0))
/// .collect();
/// for (_, balance) in map.range_mut("B".."Cheryl") {
/// *balance += 100;
/// }
/// for (name, balance) in &map {
/// println!("{} => {}", name, balance);
/// }
/// ```
#[stable(feature = "btree_range", since = "1.17.0")]
pub fn range_mut<T: ?Sized, R>(&mut self, range: R) -> RangeMut<'_, K, V>
where T: Ord, K: Borrow<T>, R: RangeBounds<T>
{
let root1 = self.root.as_mut();
let root2 = unsafe { ptr::read(&root1) };
let (f, b) = range_search(root1, root2, range);
RangeMut {
front: f,
back: b,
_marker: PhantomData,
}
}
/// Gets the given key's corresponding entry in the map for in-place manipulation.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use std::collections::BTreeMap;
///
/// let mut count: BTreeMap<&str, usize> = BTreeMap::new();
///
/// // count the number of occurrences of letters in the vec
/// for x in vec!["a","b","a","c","a","b"] {
/// *count.entry(x).or_insert(0) += 1;
/// }
///
/// assert_eq!(count["a"], 3);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn entry(&mut self, key: K) -> Entry<'_, K, V> {
// FIXME(@porglezomp) Avoid allocating if we don't insert
self.ensure_root_is_owned();
match search::search_tree(self.root.as_mut(), &key) {
Found(handle) => {
Occupied(OccupiedEntry {
handle,
length: &mut self.length,
_marker: PhantomData,
})
}
GoDown(handle) => {
Vacant(VacantEntry {
key,
handle,
length: &mut self.length,
_marker: PhantomData,
})
}
}
}
fn from_sorted_iter<I: Iterator<Item = (K, V)>>(&mut self, iter: I) {
self.ensure_root_is_owned();
let mut cur_node = last_leaf_edge(self.root.as_mut()).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.
if cur_node.len() < node::CAPACITY {
cur_node.push(key, value);
} else {
// No space left, go up and push there.
let mut open_node;
let mut test_node = cur_node.forget_type();
loop {
match test_node.ascend() {
Ok(parent) => {
let parent = parent.into_node();
if parent.len() < node::CAPACITY {
// Found a node with space left, push here.
open_node = parent;
break;
} else {
// Go up again.
test_node = parent.forget_type();
}
}
Err(node) => {
// We are at the top, create a new root node and push there.
open_node = node.into_root_mut().push_level();
break;
}
}
}
// Push key-value pair and new right subtree.
let tree_height = open_node.height() - 1;
let mut right_tree = node::Root::new_leaf();
for _ in 0..tree_height {
right_tree.push_level();
}
open_node.push(key, value, right_tree);
// Go down to the right-most leaf again.
cur_node = last_leaf_edge(open_node.forget_type()).into_node();
}
self.length += 1;
}
}
fn fix_right_edge(&mut self) {
// Handle underfull nodes, start from the top.
let mut cur_node = self.root.as_mut();
while let Internal(internal) = cur_node.force() {
// Check if right-most child is underfull.
let mut last_edge = internal.last_edge();
let right_child_len = last_edge.reborrow().descend().len();
if right_child_len < node::MIN_LEN {
// We need to steal.
let mut last_kv = match last_edge.left_kv() {
Ok(left) => left,
Err(_) => unreachable!(),
};
last_kv.bulk_steal_left(node::MIN_LEN - right_child_len);
last_edge = last_kv.right_edge();
}
// Go further down.
cur_node = last_edge.descend();
}
}
/// Splits the collection into two at the given key. Returns everything after the given key,
/// including the key.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use std::collections::BTreeMap;
///
/// let mut a = BTreeMap::new();
/// a.insert(1, "a");
/// a.insert(2, "b");
/// a.insert(3, "c");
/// a.insert(17, "d");
/// a.insert(41, "e");
///
/// let b = a.split_off(&3);
///
/// assert_eq!(a.len(), 2);
/// assert_eq!(b.len(), 3);
///
/// assert_eq!(a[&1], "a");
/// assert_eq!(a[&2], "b");
///
/// assert_eq!(b[&3], "c");
/// assert_eq!(b[&17], "d");
/// assert_eq!(b[&41], "e");
/// ```
#[stable(feature = "btree_split_off", since = "1.11.0")]
pub fn split_off<Q: ?Sized + Ord>(&mut self, key: &Q) -> Self
where K: Borrow<Q>
{
if self.is_empty() {
return Self::new();
}
let total_num = self.len();
let mut right = Self::new();
right.root = node::Root::new_leaf();
for _ in 0..(self.root.as_ref().height()) {
right.root.push_level();
}
{
let mut left_node = self.root.as_mut();
let mut right_node = right.root.as_mut();
loop {
let mut split_edge = match search::search_node(left_node, key) {
// key is going to the right tree
Found(handle) => handle.left_edge(),
GoDown(handle) => handle,
};
split_edge.move_suffix(&mut right_node);
match (split_edge.force(), right_node.force()) {
(Internal(edge), Internal(node)) => {
left_node = edge.descend();
right_node = node.first_edge().descend();
}
(Leaf(_), Leaf(_)) => {
break;
}
_ => {
unreachable!();
}
}
}
}
self.fix_right_border();
right.fix_left_border();
if self.root.as_ref().height() < right.root.as_ref().height() {
self.recalc_length();
right.length = total_num - self.len();
} else {
right.recalc_length();
self.length = total_num - right.len();
}
right
}
/// Calculates the number of elements if it is incorrect.
fn recalc_length(&mut self) {
fn dfs<'a, K, V>(
node: NodeRef<marker::Immut<'a>, K, V, marker::LeafOrInternal>
) -> usize
where K: 'a, V: 'a
{
let mut res = node.len();
if let Internal(node) = node.force() {
let mut edge = node.first_edge();
loop {
res += dfs(edge.reborrow().descend());
match edge.right_kv() {
Ok(right_kv) => {
edge = right_kv.right_edge();
}
Err(_) => {
break;
}
}
}
}
res
}
self.length = dfs(self.root.as_ref());
}
/// Removes empty levels on the top.
fn fix_top(&mut self) {
loop {
{
let node = self.root.as_ref();
if node.height() == 0 || node.len() > 0 {
break;
}
}
self.root.pop_level();
}
}
fn fix_right_border(&mut self) {
self.fix_top();
{
let mut cur_node = self.root.as_mut();
while let Internal(node) = cur_node.force() {
let mut last_kv = node.last_kv();
if last_kv.can_merge() {
cur_node = last_kv.merge().descend();
} else {
let right_len = last_kv.reborrow().right_edge().descend().len();
// `MINLEN + 1` to avoid readjust if merge happens on the next level.
if right_len < node::MIN_LEN + 1 {
last_kv.bulk_steal_left(node::MIN_LEN + 1 - right_len);
}
cur_node = last_kv.right_edge().descend();
}
}
}
self.fix_top();
}
/// The symmetric clone of `fix_right_border`.
fn fix_left_border(&mut self) {
self.fix_top();
{
let mut cur_node = self.root.as_mut();
while let Internal(node) = cur_node.force() {
let mut first_kv = node.first_kv();
if first_kv.can_merge() {
cur_node = first_kv.merge().descend();
} else {
let left_len = first_kv.reborrow().left_edge().descend().len();
if left_len < node::MIN_LEN + 1 {
first_kv.bulk_steal_right(node::MIN_LEN + 1 - left_len);
}
cur_node = first_kv.left_edge().descend();
}
}
}
self.fix_top();
}
/// If the root node is the shared root node, allocate our own node.
fn ensure_root_is_owned(&mut self) {
if self.root.is_shared_root() {
self.root = node::Root::new_leaf();
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K: 'a, V: 'a> IntoIterator for &'a BTreeMap<K, V> {
type Item = (&'a K, &'a V);
type IntoIter = Iter<'a, K, V>;
fn into_iter(self) -> Iter<'a, K, V> {
self.iter()
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K: 'a, V: 'a> Iterator for Iter<'a, K, V> {
type Item = (&'a K, &'a V);
fn next(&mut self) -> Option<(&'a K, &'a V)> {
if self.length == 0 {
None
} else {
self.length -= 1;
unsafe { Some(self.range.next_unchecked()) }
}
}
fn size_hint(&self) -> (usize, Option<usize>) {
(self.length, Some(self.length))
}
fn last(mut self) -> Option<(&'a K, &'a V)> {
self.next_back()
}
}
#[stable(feature = "fused", since = "1.26.0")]
impl<K, V> FusedIterator for Iter<'_, K, V> {}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K: 'a, V: 'a> DoubleEndedIterator for Iter<'a, K, V> {
fn next_back(&mut self) -> Option<(&'a K, &'a V)> {
if self.length == 0 {
None
} else {
self.length -= 1;
unsafe { Some(self.range.next_back_unchecked()) }
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V> ExactSizeIterator for Iter<'_, K, V> {
fn len(&self) -> usize {
self.length
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V> Clone for Iter<'_, K, V> {
fn clone(&self) -> Self {
Iter {
range: self.range.clone(),
length: self.length,
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K: 'a, V: 'a> IntoIterator for &'a mut BTreeMap<K, V> {
type Item = (&'a K, &'a mut V);
type IntoIter = IterMut<'a, K, V>;
fn into_iter(self) -> IterMut<'a, K, V> {
self.iter_mut()
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K: 'a, V: 'a> Iterator for IterMut<'a, K, V> {
type Item = (&'a K, &'a mut V);
fn next(&mut self) -> Option<(&'a K, &'a mut V)> {
if self.length == 0 {
None
} else {
self.length -= 1;
unsafe { Some(self.range.next_unchecked()) }
}
}
fn size_hint(&self) -> (usize, Option<usize>) {
(self.length, Some(self.length))
}
fn last(mut self) -> Option<(&'a K, &'a mut V)> {
self.next_back()
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K: 'a, V: 'a> DoubleEndedIterator for IterMut<'a, K, V> {
fn next_back(&mut self) -> Option<(&'a K, &'a mut V)> {
if self.length == 0 {
None
} else {
self.length -= 1;
unsafe { Some(self.range.next_back_unchecked()) }
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V> ExactSizeIterator for IterMut<'_, K, V> {
fn len(&self) -> usize {
self.length
}
}
#[stable(feature = "fused", since = "1.26.0")]
impl<K, V> FusedIterator for IterMut<'_, K, V> {}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V> IntoIterator for BTreeMap<K, V> {
type Item = (K, V);
type IntoIter = IntoIter<K, V>;
fn into_iter(self) -> IntoIter<K, V> {
let root1 = unsafe { ptr::read(&self.root).into_ref() };
let root2 = unsafe { ptr::read(&self.root).into_ref() };
let len = self.length;
mem::forget(self);
IntoIter {
front: first_leaf_edge(root1),
back: last_leaf_edge(root2),
length: len,
}
}
}
#[stable(feature = "btree_drop", since = "1.7.0")]
impl<K, V> Drop for IntoIter<K, V> {
fn drop(&mut self) {
self.for_each(drop);
unsafe {
let leaf_node = ptr::read(&self.front).into_node();
if leaf_node.is_shared_root() {
return;
}
if let Some(first_parent) = leaf_node.deallocate_and_ascend() {
let mut cur_node = first_parent.into_node();
while let Some(parent) = cur_node.deallocate_and_ascend() {
cur_node = parent.into_node()
}
}
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V> Iterator for IntoIter<K, V> {
type Item = (K, V);
fn next(&mut self) -> Option<(K, V)> {
if self.length == 0 {
return None;
} else {
self.length -= 1;
}
let handle = unsafe { ptr::read(&self.front) };
let mut cur_handle = match handle.right_kv() {
Ok(kv) => {
let k = unsafe { ptr::read(kv.reborrow().into_kv().0) };
let v = unsafe { ptr::read(kv.reborrow().into_kv().1) };
self.front = kv.right_edge();
return Some((k, v));
}
Err(last_edge) => unsafe {
unwrap_unchecked(last_edge.into_node().deallocate_and_ascend())
},
};
loop {
match cur_handle.right_kv() {
Ok(kv) => {
let k = unsafe { ptr::read(kv.reborrow().into_kv().0) };
let v = unsafe { ptr::read(kv.reborrow().into_kv().1) };
self.front = first_leaf_edge(kv.right_edge().descend());
return Some((k, v));
}
Err(last_edge) => unsafe {
cur_handle = unwrap_unchecked(last_edge.into_node().deallocate_and_ascend());
},
}
}
}
fn size_hint(&self) -> (usize, Option<usize>) {
(self.length, Some(self.length))
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V> DoubleEndedIterator for IntoIter<K, V> {
fn next_back(&mut self) -> Option<(K, V)> {
if self.length == 0 {
return None;
} else {
self.length -= 1;
}
let handle = unsafe { ptr::read(&self.back) };
let mut cur_handle = match handle.left_kv() {
Ok(kv) => {
let k = unsafe { ptr::read(kv.reborrow().into_kv().0) };
let v = unsafe { ptr::read(kv.reborrow().into_kv().1) };
self.back = kv.left_edge();
return Some((k, v));
}
Err(last_edge) => unsafe {
unwrap_unchecked(last_edge.into_node().deallocate_and_ascend())
},
};
loop {
match cur_handle.left_kv() {
Ok(kv) => {
let k = unsafe { ptr::read(kv.reborrow().into_kv().0) };
let v = unsafe { ptr::read(kv.reborrow().into_kv().1) };
self.back = last_leaf_edge(kv.left_edge().descend());
return Some((k, v));
}
Err(last_edge) => unsafe {
cur_handle = unwrap_unchecked(last_edge.into_node().deallocate_and_ascend());
},
}
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V> ExactSizeIterator for IntoIter<K, V> {
fn len(&self) -> usize {
self.length
}
}
#[stable(feature = "fused", since = "1.26.0")]
impl<K, V> FusedIterator for IntoIter<K, V> {}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K, V> Iterator for Keys<'a, K, V> {
type Item = &'a K;
fn next(&mut self) -> Option<&'a K> {
self.inner.next().map(|(k, _)| k)
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.inner.size_hint()
}
fn last(mut self) -> Option<&'a K> {
self.next_back()
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K, V> DoubleEndedIterator for Keys<'a, K, V> {
fn next_back(&mut self) -> Option<&'a K> {
self.inner.next_back().map(|(k, _)| k)
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V> ExactSizeIterator for Keys<'_, K, V> {
fn len(&self) -> usize {
self.inner.len()
}
}
#[stable(feature = "fused", since = "1.26.0")]
impl<K, V> FusedIterator for Keys<'_, K, V> {}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V> Clone for Keys<'_, K, V> {
fn clone(&self) -> Self {
Keys { inner: self.inner.clone() }
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K, V> Iterator for Values<'a, K, V> {
type Item = &'a V;
fn next(&mut self) -> Option<&'a V> {
self.inner.next().map(|(_, v)| v)
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.inner.size_hint()
}
fn last(mut self) -> Option<&'a V> {
self.next_back()
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K, V> DoubleEndedIterator for Values<'a, K, V> {
fn next_back(&mut self) -> Option<&'a V> {
self.inner.next_back().map(|(_, v)| v)
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V> ExactSizeIterator for Values<'_, K, V> {
fn len(&self) -> usize {
self.inner.len()
}
}
#[stable(feature = "fused", since = "1.26.0")]
impl<K, V> FusedIterator for Values<'_, K, V> {}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V> Clone for Values<'_, K, V> {
fn clone(&self) -> Self {
Values { inner: self.inner.clone() }
}
}
#[stable(feature = "btree_range", since = "1.17.0")]
impl<'a, K, V> Iterator for Range<'a, K, V> {
type Item = (&'a K, &'a V);
fn next(&mut self) -> Option<(&'a K, &'a V)> {
if self.front == self.back {
None
} else {
unsafe { Some(self.next_unchecked()) }
}
}
fn last(mut self) -> Option<(&'a K, &'a V)> {
self.next_back()
}
}
#[stable(feature = "map_values_mut", since = "1.10.0")]
impl<'a, K, V> Iterator for ValuesMut<'a, K, V> {
type Item = &'a mut V;
fn next(&mut self) -> Option<&'a mut V> {
self.inner.next().map(|(_, v)| v)
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.inner.size_hint()
}
fn last(mut self) -> Option<&'a mut V> {
self.next_back()
}
}
#[stable(feature = "map_values_mut", since = "1.10.0")]
impl<'a, K, V> DoubleEndedIterator for ValuesMut<'a, K, V> {
fn next_back(&mut self) -> Option<&'a mut V> {
self.inner.next_back().map(|(_, v)| v)
}
}
#[stable(feature = "map_values_mut", since = "1.10.0")]
impl<K, V> ExactSizeIterator for ValuesMut<'_, K, V> {
fn len(&self) -> usize {
self.inner.len()
}
}
#[stable(feature = "fused", since = "1.26.0")]
impl<K, V> FusedIterator for ValuesMut<'_, K, V> {}
impl<'a, K, V> Range<'a, K, V> {
unsafe fn next_unchecked(&mut self) -> (&'a K, &'a V) {
let handle = self.front;
let mut cur_handle = match handle.right_kv() {
Ok(kv) => {
let ret = kv.into_kv();
self.front = kv.right_edge();
return ret;
}
Err(last_edge) => {
let next_level = last_edge.into_node().ascend().ok();
unwrap_unchecked(next_level)
}
};
loop {
match cur_handle.right_kv() {
Ok(kv) => {
let ret = kv.into_kv();
self.front = first_leaf_edge(kv.right_edge().descend());
return ret;
}
Err(last_edge) => {
let next_level = last_edge.into_node().ascend().ok();
cur_handle = unwrap_unchecked(next_level);
}
}
}
}
}
#[stable(feature = "btree_range", since = "1.17.0")]
impl<'a, K, V> DoubleEndedIterator for Range<'a, K, V> {
fn next_back(&mut self) -> Option<(&'a K, &'a V)> {
if self.front == self.back {
None
} else {
unsafe { Some(self.next_back_unchecked()) }
}
}
}
impl<'a, K, V> Range<'a, K, V> {
unsafe fn next_back_unchecked(&mut self) -> (&'a K, &'a V) {
let handle = self.back;
let mut cur_handle = match handle.left_kv() {
Ok(kv) => {
let ret = kv.into_kv();
self.back = kv.left_edge();
return ret;
}
Err(last_edge) => {
let next_level = last_edge.into_node().ascend().ok();
unwrap_unchecked(next_level)
}
};
loop {
match cur_handle.left_kv() {
Ok(kv) => {
let ret = kv.into_kv();
self.back = last_leaf_edge(kv.left_edge().descend());
return ret;
}
Err(last_edge) => {
let next_level = last_edge.into_node().ascend().ok();
cur_handle = unwrap_unchecked(next_level);
}
}
}
}
}
#[stable(feature = "fused", since = "1.26.0")]
impl<K, V> FusedIterator for Range<'_, K, V> {}
#[stable(feature = "btree_range", since = "1.17.0")]
impl<K, V> Clone for Range<'_, K, V> {
fn clone(&self) -> Self {
Range {
front: self.front,
back: self.back,
}
}
}
#[stable(feature = "btree_range", since = "1.17.0")]
impl<'a, K, V> Iterator for RangeMut<'a, K, V> {
type Item = (&'a K, &'a mut V);
fn next(&mut self) -> Option<(&'a K, &'a mut V)> {
if self.front == self.back {
None
} else {
unsafe { Some(self.next_unchecked()) }
}
}
fn last(mut self) -> Option<(&'a K, &'a mut V)> {
self.next_back()
}
}
impl<'a, K, V> RangeMut<'a, K, V> {
unsafe fn next_unchecked(&mut self) -> (&'a K, &'a mut V) {
let handle = ptr::read(&self.front);
let mut cur_handle = match handle.right_kv() {
Ok(kv) => {
self.front = ptr::read(&kv).right_edge();
// Doing the descend invalidates the references returned by `into_kv_mut`,
// so we have to do this last.
let (k, v) = kv.into_kv_mut();
return (k, v); // coerce k from `&mut K` to `&K`
}
Err(last_edge) => {
let next_level = last_edge.into_node().ascend().ok();
unwrap_unchecked(next_level)
}
};
loop {
match cur_handle.right_kv() {
Ok(kv) => {
self.front = first_leaf_edge(ptr::read(&kv).right_edge().descend());
// Doing the descend invalidates the references returned by `into_kv_mut`,
// so we have to do this last.
let (k, v) = kv.into_kv_mut();
return (k, v); // coerce k from `&mut K` to `&K`
}
Err(last_edge) => {
let next_level = last_edge.into_node().ascend().ok();
cur_handle = unwrap_unchecked(next_level);
}
}
}
}
}
#[stable(feature = "btree_range", since = "1.17.0")]
impl<'a, K, V> DoubleEndedIterator for RangeMut<'a, K, V> {
fn next_back(&mut self) -> Option<(&'a K, &'a mut V)> {
if self.front == self.back {
None
} else {
unsafe { Some(self.next_back_unchecked()) }
}
}
}
#[stable(feature = "fused", since = "1.26.0")]
impl<K, V> FusedIterator for RangeMut<'_, K, V> {}
impl<'a, K, V> RangeMut<'a, K, V> {
unsafe fn next_back_unchecked(&mut self) -> (&'a K, &'a mut V) {
let handle = ptr::read(&self.back);
let mut cur_handle = match handle.left_kv() {
Ok(kv) => {
self.back = ptr::read(&kv).left_edge();
// Doing the descend invalidates the references returned by `into_kv_mut`,
// so we have to do this last.
let (k, v) = kv.into_kv_mut();
return (k, v); // coerce k from `&mut K` to `&K`
}
Err(last_edge) => {
let next_level = last_edge.into_node().ascend().ok();
unwrap_unchecked(next_level)
}
};
loop {
match cur_handle.left_kv() {
Ok(kv) => {
self.back = last_leaf_edge(ptr::read(&kv).left_edge().descend());
// Doing the descend invalidates the references returned by `into_kv_mut`,
// so we have to do this last.
let (k, v) = kv.into_kv_mut();
return (k, v); // coerce k from `&mut K` to `&K`
}
Err(last_edge) => {
let next_level = last_edge.into_node().ascend().ok();
cur_handle = unwrap_unchecked(next_level);
}
}
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K: Ord, V> FromIterator<(K, V)> for BTreeMap<K, V> {
fn from_iter<T: IntoIterator<Item = (K, V)>>(iter: T) -> BTreeMap<K, V> {
let mut map = BTreeMap::new();
map.extend(iter);
map
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K: Ord, V> Extend<(K, V)> for BTreeMap<K, V> {
#[inline]
fn extend<T: IntoIterator<Item = (K, V)>>(&mut self, iter: T) {
iter.into_iter().for_each(move |(k, v)| {
self.insert(k, v);
});
}
}
#[stable(feature = "extend_ref", since = "1.2.0")]
impl<'a, K: Ord + Copy, V: Copy> Extend<(&'a K, &'a V)> for BTreeMap<K, V> {
fn extend<I: IntoIterator<Item = (&'a K, &'a V)>>(&mut self, iter: I) {
self.extend(iter.into_iter().map(|(&key, &value)| (key, value)));
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K: Hash, V: Hash> Hash for BTreeMap<K, V> {
fn hash<H: Hasher>(&self, state: &mut H) {
for elt in self {
elt.hash(state);
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K: Ord, V> Default for BTreeMap<K, V> {
/// Creates an empty `BTreeMap<K, V>`.
fn default() -> BTreeMap<K, V> {
BTreeMap::new()
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K: PartialEq, V: PartialEq> PartialEq for BTreeMap<K, V> {
fn eq(&self, other: &BTreeMap<K, V>) -> bool {
self.len() == other.len() && self.iter().zip(other).all(|(a, b)| a == b)
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K: Eq, V: Eq> Eq for BTreeMap<K, V> {}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K: PartialOrd, V: PartialOrd> PartialOrd for BTreeMap<K, V> {
#[inline]
fn partial_cmp(&self, other: &BTreeMap<K, V>) -> Option<Ordering> {
self.iter().partial_cmp(other.iter())
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K: Ord, V: Ord> Ord for BTreeMap<K, V> {
#[inline]
fn cmp(&self, other: &BTreeMap<K, V>) -> Ordering {
self.iter().cmp(other.iter())
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K: Debug, V: Debug> Debug for BTreeMap<K, V> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_map().entries(self.iter()).finish()
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K: Ord, Q: ?Sized, V> Index<&Q> for BTreeMap<K, V>
where K: Borrow<Q>,
Q: Ord
{
type Output = V;
/// Returns a reference to the value corresponding to the supplied key.
///
/// # Panics
///
/// Panics if the key is not present in the `BTreeMap`.
#[inline]
fn index(&self, key: &Q) -> &V {
self.get(key).expect("no entry found for key")
}
}
fn first_leaf_edge<BorrowType, K, V>
(mut node: NodeRef<BorrowType, K, V, marker::LeafOrInternal>)
-> Handle<NodeRef<BorrowType, K, V, marker::Leaf>, marker::Edge> {
loop {
match node.force() {
Leaf(leaf) => return leaf.first_edge(),
Internal(internal) => {
node = internal.first_edge().descend();
}
}
}
}
fn last_leaf_edge<BorrowType, K, V>
(mut node: NodeRef<BorrowType, K, V, marker::LeafOrInternal>)
-> Handle<NodeRef<BorrowType, K, V, marker::Leaf>, marker::Edge> {
loop {
match node.force() {
Leaf(leaf) => return leaf.last_edge(),
Internal(internal) => {
node = internal.last_edge().descend();
}
}
}
}
fn range_search<BorrowType, K, V, Q: ?Sized, R: RangeBounds<Q>>(
root1: NodeRef<BorrowType, K, V, marker::LeafOrInternal>,
root2: NodeRef<BorrowType, K, V, marker::LeafOrInternal>,
range: R
)-> (Handle<NodeRef<BorrowType, K, V, marker::Leaf>, marker::Edge>,
Handle<NodeRef<BorrowType, K, V, marker::Leaf>, marker::Edge>)
where Q: Ord, K: Borrow<Q>
{
match (range.start_bound(), range.end_bound()) {
(Excluded(s), Excluded(e)) if s==e =>
panic!("range start and end are equal and excluded in BTreeMap"),
(Included(s), Included(e)) |
(Included(s), Excluded(e)) |
(Excluded(s), Included(e)) |
(Excluded(s), Excluded(e)) if s>e =>
panic!("range start is greater than range end in BTreeMap"),
_ => {},
};
let mut min_node = root1;
let mut max_node = root2;
let mut min_found = false;
let mut max_found = false;
let mut diverged = false;
loop {
let min_edge = match (min_found, range.start_bound()) {
(false, Included(key)) => match search::search_linear(&min_node, key) {
(i, true) => { min_found = true; i },
(i, false) => i,
},
(false, Excluded(key)) => match search::search_linear(&min_node, key) {
(i, true) => { min_found = true; i+1 },
(i, false) => i,
},
(_, Unbounded) => 0,
(true, Included(_)) => min_node.keys().len(),
(true, Excluded(_)) => 0,
};
let max_edge = match (max_found, range.end_bound()) {
(false, Included(key)) => match search::search_linear(&max_node, key) {
(i, true) => { max_found = true; i+1 },
(i, false) => i,
},
(false, Excluded(key)) => match search::search_linear(&max_node, key) {
(i, true) => { max_found = true; i },
(i, false) => i,
},
(_, Unbounded) => max_node.keys().len(),
(true, Included(_)) => 0,
(true, Excluded(_)) => max_node.keys().len(),
};
if !diverged {
if max_edge < min_edge { panic!("Ord is ill-defined in BTreeMap range") }
if min_edge != max_edge { diverged = true; }
}
let front = Handle::new_edge(min_node, min_edge);
let back = Handle::new_edge(max_node, max_edge);
match (front.force(), back.force()) {
(Leaf(f), Leaf(b)) => {
return (f, b);
},
(Internal(min_int), Internal(max_int)) => {
min_node = min_int.descend();
max_node = max_int.descend();
},
_ => unreachable!("BTreeMap has different depths"),
};
}
}
#[inline(always)]
unsafe fn unwrap_unchecked<T>(val: Option<T>) -> T {
val.unwrap_or_else(|| {
if cfg!(debug_assertions) {
panic!("'unchecked' unwrap on None in BTreeMap");
} else {
intrinsics::unreachable();
}
})
}
impl<K, V> BTreeMap<K, V> {
/// Gets an iterator over the entries of the map, sorted by key.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use std::collections::BTreeMap;
///
/// let mut map = BTreeMap::new();
/// map.insert(3, "c");
/// map.insert(2, "b");
/// map.insert(1, "a");
///
/// for (key, value) in map.iter() {
/// println!("{}: {}", key, value);
/// }
///
/// let (first_key, first_value) = map.iter().next().unwrap();
/// assert_eq!((*first_key, *first_value), (1, "a"));
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn iter(&self) -> Iter<'_, K, V> {
Iter {
range: Range {
front: first_leaf_edge(self.root.as_ref()),
back: last_leaf_edge(self.root.as_ref()),
},
length: self.length,
}
}
/// Gets a mutable iterator over the entries of the map, sorted by key.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use std::collections::BTreeMap;
///
/// let mut map = BTreeMap::new();
/// map.insert("a", 1);
/// map.insert("b", 2);
/// map.insert("c", 3);
///
/// // add 10 to the value if the key isn't "a"
/// for (key, value) in map.iter_mut() {
/// if key != &"a" {
/// *value += 10;
/// }
/// }
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn iter_mut(&mut self) -> IterMut<'_, K, V> {
let root1 = self.root.as_mut();
let root2 = unsafe { ptr::read(&root1) };
IterMut {
range: RangeMut {
front: first_leaf_edge(root1),
back: last_leaf_edge(root2),
_marker: PhantomData,
},
length: self.length,
}
}
/// Gets an iterator over the keys of the map, in sorted order.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use std::collections::BTreeMap;
///
/// let mut a = BTreeMap::new();
/// a.insert(2, "b");
/// a.insert(1, "a");
///
/// let keys: Vec<_> = a.keys().cloned().collect();
/// assert_eq!(keys, [1, 2]);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn keys(&self) -> Keys<'_, K, V> {
Keys { inner: self.iter() }
}
/// Gets an iterator over the values of the map, in order by key.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use std::collections::BTreeMap;
///
/// let mut a = BTreeMap::new();
/// a.insert(1, "hello");
/// a.insert(2, "goodbye");
///
/// let values: Vec<&str> = a.values().cloned().collect();
/// assert_eq!(values, ["hello", "goodbye"]);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn values(&self) -> Values<'_, K, V> {
Values { inner: self.iter() }
}
/// Gets a mutable iterator over the values of the map, in order by key.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use std::collections::BTreeMap;
///
/// let mut a = BTreeMap::new();
/// a.insert(1, String::from("hello"));
/// a.insert(2, String::from("goodbye"));
///
/// for value in a.values_mut() {
/// value.push_str("!");
/// }
///
/// let values: Vec<String> = a.values().cloned().collect();
/// assert_eq!(values, [String::from("hello!"),
/// String::from("goodbye!")]);
/// ```
#[stable(feature = "map_values_mut", since = "1.10.0")]
pub fn values_mut(&mut self) -> ValuesMut<'_, K, V> {
ValuesMut { inner: self.iter_mut() }
}
/// Returns the number of elements in the map.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use std::collections::BTreeMap;
///
/// let mut a = BTreeMap::new();
/// assert_eq!(a.len(), 0);
/// a.insert(1, "a");
/// assert_eq!(a.len(), 1);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn len(&self) -> usize {
self.length
}
/// Returns `true` if the map contains no elements.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use std::collections::BTreeMap;
///
/// let mut a = BTreeMap::new();
/// assert!(a.is_empty());
/// a.insert(1, "a");
/// assert!(!a.is_empty());
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn is_empty(&self) -> bool {
self.len() == 0
}
}
impl<'a, K: Ord, V> Entry<'a, K, V> {
/// Ensures a value is in the entry by inserting the default if empty, and returns
/// a mutable reference to the value in the entry.
///
/// # Examples
///
/// ```
/// use std::collections::BTreeMap;
///
/// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
/// map.entry("poneyland").or_insert(12);
///
/// assert_eq!(map["poneyland"], 12);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn or_insert(self, default: V) -> &'a mut V {
match self {
Occupied(entry) => entry.into_mut(),
Vacant(entry) => entry.insert(default),
}
}
/// Ensures a value is in the entry by inserting the result of the default function if empty,
/// and returns a mutable reference to the value in the entry.
///
/// # Examples
///
/// ```
/// use std::collections::BTreeMap;
///
/// let mut map: BTreeMap<&str, String> = BTreeMap::new();
/// let s = "hoho".to_string();
///
/// map.entry("poneyland").or_insert_with(|| s);
///
/// assert_eq!(map["poneyland"], "hoho".to_string());
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn or_insert_with<F: FnOnce() -> V>(self, default: F) -> &'a mut V {
match self {
Occupied(entry) => entry.into_mut(),
Vacant(entry) => entry.insert(default()),
}
}
/// Returns a reference to this entry's key.
///
/// # Examples
///
/// ```
/// use std::collections::BTreeMap;
///
/// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
/// assert_eq!(map.entry("poneyland").key(), &"poneyland");
/// ```
#[stable(feature = "map_entry_keys", since = "1.10.0")]
pub fn key(&self) -> &K {
match *self {
Occupied(ref entry) => entry.key(),
Vacant(ref entry) => entry.key(),
}
}
/// Provides in-place mutable access to an occupied entry before any
/// potential inserts into the map.
///
/// # Examples
///
/// ```
/// use std::collections::BTreeMap;
///
/// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
///
/// map.entry("poneyland")
/// .and_modify(|e| { *e += 1 })
/// .or_insert(42);
/// assert_eq!(map["poneyland"], 42);
///
/// map.entry("poneyland")
/// .and_modify(|e| { *e += 1 })
/// .or_insert(42);
/// assert_eq!(map["poneyland"], 43);
/// ```
#[stable(feature = "entry_and_modify", since = "1.26.0")]
pub fn and_modify<F>(self, f: F) -> Self
where F: FnOnce(&mut V)
{
match self {
Occupied(mut entry) => {
f(entry.get_mut());
Occupied(entry)
},
Vacant(entry) => Vacant(entry),
}
}
}
impl<'a, K: Ord, V: Default> Entry<'a, K, V> {
#[stable(feature = "entry_or_default", since = "1.28.0")]
/// Ensures a value is in the entry by inserting the default value if empty,
/// and returns a mutable reference to the value in the entry.
///
/// # Examples
///
/// ```
/// # fn main() {
/// use std::collections::BTreeMap;
///
/// let mut map: BTreeMap<&str, Option<usize>> = BTreeMap::new();
/// map.entry("poneyland").or_default();
///
/// assert_eq!(map["poneyland"], None);
/// # }
/// ```
pub fn or_default(self) -> &'a mut V {
match self {
Occupied(entry) => entry.into_mut(),
Vacant(entry) => entry.insert(Default::default()),
}
}
}
impl<'a, K: Ord, V> VacantEntry<'a, K, V> {
/// Gets a reference to the key that would be used when inserting a value
/// through the VacantEntry.
///
/// # Examples
///
/// ```
/// use std::collections::BTreeMap;
///
/// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
/// assert_eq!(map.entry("poneyland").key(), &"poneyland");
/// ```
#[stable(feature = "map_entry_keys", since = "1.10.0")]
pub fn key(&self) -> &K {
&self.key
}
/// Take ownership of the key.
///
/// # Examples
///
/// ```
/// use std::collections::BTreeMap;
/// use std::collections::btree_map::Entry;
///
/// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
///
/// if let Entry::Vacant(v) = map.entry("poneyland") {
/// v.into_key();
/// }
/// ```
#[stable(feature = "map_entry_recover_keys2", since = "1.12.0")]
pub fn into_key(self) -> K {
self.key
}
/// Sets the value of the entry with the `VacantEntry`'s key,
/// and returns a mutable reference to it.
///
/// # Examples
///
/// ```
/// use std::collections::BTreeMap;
///
/// let mut count: BTreeMap<&str, usize> = BTreeMap::new();
///
/// // count the number of occurrences of letters in the vec
/// for x in vec!["a","b","a","c","a","b"] {
/// *count.entry(x).or_insert(0) += 1;
/// }
///
/// assert_eq!(count["a"], 3);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn insert(self, value: V) -> &'a mut V {
*self.length += 1;
let out_ptr;
let mut ins_k;
let mut ins_v;
let mut ins_edge;
let mut cur_parent = match self.handle.insert(self.key, value) {
(Fit(handle), _) => return handle.into_kv_mut().1,
(Split(left, k, v, right), ptr) => {
ins_k = k;
ins_v = v;
ins_edge = right;
out_ptr = ptr;
left.ascend().map_err(|n| n.into_root_mut())
}
};
loop {
match cur_parent {
Ok(parent) => {
match parent.insert(ins_k, ins_v, ins_edge) {
Fit(_) => return unsafe { &mut *out_ptr },
Split(left, k, v, right) => {
ins_k = k;
ins_v = v;
ins_edge = right;
cur_parent = left.ascend().map_err(|n| n.into_root_mut());
}
}
}
Err(root) => {
root.push_level().push(ins_k, ins_v, ins_edge);
return unsafe { &mut *out_ptr };
}
}
}
}
}
impl<'a, K: Ord, V> OccupiedEntry<'a, K, V> {
/// Gets a reference to the key in the entry.
///
/// # Examples
///
/// ```
/// use std::collections::BTreeMap;
///
/// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
/// map.entry("poneyland").or_insert(12);
/// assert_eq!(map.entry("poneyland").key(), &"poneyland");
/// ```
#[stable(feature = "map_entry_keys", since = "1.10.0")]
pub fn key(&self) -> &K {
self.handle.reborrow().into_kv().0
}
/// Take ownership of the key and value from the map.
///
/// # Examples
///
/// ```
/// use std::collections::BTreeMap;
/// use std::collections::btree_map::Entry;
///
/// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
/// map.entry("poneyland").or_insert(12);
///
/// if let Entry::Occupied(o) = map.entry("poneyland") {
/// // We delete the entry from the map.
/// o.remove_entry();
/// }
///
/// // If now try to get the value, it will panic:
/// // println!("{}", map["poneyland"]);
/// ```
#[stable(feature = "map_entry_recover_keys2", since = "1.12.0")]
pub fn remove_entry(self) -> (K, V) {
self.remove_kv()
}
/// Gets a reference to the value in the entry.
///
/// # Examples
///
/// ```
/// use std::collections::BTreeMap;
/// use std::collections::btree_map::Entry;
///
/// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
/// map.entry("poneyland").or_insert(12);
///
/// if let Entry::Occupied(o) = map.entry("poneyland") {
/// assert_eq!(o.get(), &12);
/// }
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn get(&self) -> &V {
self.handle.reborrow().into_kv().1
}
/// Gets a mutable reference to the value in the entry.
///
/// If you need a reference to the `OccupiedEntry` that may outlive the
/// destruction of the `Entry` value, see [`into_mut`].
///
/// [`into_mut`]: #method.into_mut
///
/// # Examples
///
/// ```
/// use std::collections::BTreeMap;
/// use std::collections::btree_map::Entry;
///
/// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
/// map.entry("poneyland").or_insert(12);
///
/// assert_eq!(map["poneyland"], 12);
/// if let Entry::Occupied(mut o) = map.entry("poneyland") {
/// *o.get_mut() += 10;
/// assert_eq!(*o.get(), 22);
///
/// // We can use the same Entry multiple times.
/// *o.get_mut() += 2;
/// }
/// assert_eq!(map["poneyland"], 24);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn get_mut(&mut self) -> &mut V {
self.handle.kv_mut().1
}
/// Converts the entry into a mutable reference to its value.
///
/// If you need multiple references to the `OccupiedEntry`, see [`get_mut`].
///
/// [`get_mut`]: #method.get_mut
///
/// # Examples
///
/// ```
/// use std::collections::BTreeMap;
/// use std::collections::btree_map::Entry;
///
/// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
/// map.entry("poneyland").or_insert(12);
///
/// assert_eq!(map["poneyland"], 12);
/// if let Entry::Occupied(o) = map.entry("poneyland") {
/// *o.into_mut() += 10;
/// }
/// assert_eq!(map["poneyland"], 22);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn into_mut(self) -> &'a mut V {
self.handle.into_kv_mut().1
}
/// Sets the value of the entry with the `OccupiedEntry`'s key,
/// and returns the entry's old value.
///
/// # Examples
///
/// ```
/// use std::collections::BTreeMap;
/// use std::collections::btree_map::Entry;
///
/// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
/// map.entry("poneyland").or_insert(12);
///
/// if let Entry::Occupied(mut o) = map.entry("poneyland") {
/// assert_eq!(o.insert(15), 12);
/// }
/// assert_eq!(map["poneyland"], 15);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn insert(&mut self, value: V) -> V {
mem::replace(self.get_mut(), value)
}
/// Takes the value of the entry out of the map, and returns it.
///
/// # Examples
///
/// ```
/// use std::collections::BTreeMap;
/// use std::collections::btree_map::Entry;
///
/// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
/// map.entry("poneyland").or_insert(12);
///
/// if let Entry::Occupied(o) = map.entry("poneyland") {
/// assert_eq!(o.remove(), 12);
/// }
/// // If we try to get "poneyland"'s value, it'll panic:
/// // println!("{}", map["poneyland"]);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn remove(self) -> V {
self.remove_kv().1
}
fn remove_kv(self) -> (K, V) {
*self.length -= 1;
let (small_leaf, old_key, old_val) = match self.handle.force() {
Leaf(leaf) => {
let (hole, old_key, old_val) = leaf.remove();
(hole.into_node(), old_key, old_val)
}
Internal(mut internal) => {
let key_loc = internal.kv_mut().0 as *mut K;
let val_loc = internal.kv_mut().1 as *mut V;
let to_remove = first_leaf_edge(internal.right_edge().descend()).right_kv().ok();
let to_remove = unsafe { unwrap_unchecked(to_remove) };
let (hole, key, val) = to_remove.remove();
let old_key = unsafe { mem::replace(&mut *key_loc, key) };
let old_val = unsafe { mem::replace(&mut *val_loc, val) };
(hole.into_node(), old_key, old_val)
}
};
// Handle underflow
let mut cur_node = small_leaf.forget_type();
while cur_node.len() < node::CAPACITY / 2 {
match handle_underfull_node(cur_node) {
AtRoot => break,
EmptyParent(_) => unreachable!(),
Merged(parent) => {
if parent.len() == 0 {
// We must be at the root
parent.into_root_mut().pop_level();
break;
} else {
cur_node = parent.forget_type();
}
}
Stole(_) => break,
}
}
(old_key, old_val)
}
}
enum UnderflowResult<'a, K, V> {
AtRoot,
EmptyParent(NodeRef<marker::Mut<'a>, K, V, marker::Internal>),
Merged(NodeRef<marker::Mut<'a>, K, V, marker::Internal>),
Stole(NodeRef<marker::Mut<'a>, K, V, marker::Internal>),
}
fn handle_underfull_node<K, V>(node: NodeRef<marker::Mut<'_>, K, V, marker::LeafOrInternal>)
-> UnderflowResult<'_, K, V> {
let parent = if let Ok(parent) = node.ascend() {
parent
} else {
return AtRoot;
};
let (is_left, mut handle) = match parent.left_kv() {
Ok(left) => (true, left),
Err(parent) => {
match parent.right_kv() {
Ok(right) => (false, right),
Err(parent) => {
return EmptyParent(parent.into_node());
}
}
}
};
if handle.can_merge() {
Merged(handle.merge().into_node())
} else {
if is_left {
handle.steal_left();
} else {
handle.steal_right();
}
Stole(handle.into_node())
}
}
impl<K: Ord, V, I: Iterator<Item = (K, V)>> Iterator for MergeIter<K, V, I> {
type Item = (K, V);
fn next(&mut self) -> Option<(K, V)> {
let res = match (self.left.peek(), self.right.peek()) {
(Some(&(ref left_key, _)), Some(&(ref right_key, _))) => left_key.cmp(right_key),
(Some(_), None) => Ordering::Less,
(None, Some(_)) => Ordering::Greater,
(None, None) => return None,
};
// Check which elements comes first and only advance the corresponding iterator.
// If two keys are equal, take the value from `right`.
match res {
Ordering::Less => self.left.next(),
Ordering::Greater => self.right.next(),
Ordering::Equal => {
self.left.next();
self.right.next()
}
}
}
}
You can’t perform that action at this time.