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fuchsia / third_party / rust / 57e8fc56852e7728d7160242bf13c3ab6e066bd8 / . / library / alloc / src / collections / btree / map.rs
blob: b4e9929af5ff2cd693e8430fa31d403635782c1b [file] [log] [blame]
use core::borrow::Borrow;
use core::cmp::Ordering;
use core::fmt::{self, Debug};
use core::hash::{Hash, Hasher};
use core::iter::{FromIterator, FusedIterator, Peekable};
use core::marker::PhantomData;
use core::mem::{self, ManuallyDrop};
use core::ops::{Index, RangeBounds};
use core::ptr;
use super::borrow::DormantMutRef;
use super::node::{self, marker, ForceResult::*, Handle, InsertResult::*, NodeRef};
use super::search::{self, SearchResult::*};
use super::unwrap_unchecked;
use Entry::*;
use UnderflowResult::*;
/// 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(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.
///
/// [`Cell`]: core::cell::Cell
/// [`RefCell`]: core::cell::RefCell
///
/// # 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`], which allows for more complex
/// methods of getting, setting, updating and removing keys and their values:
///
/// [`Entry API`]: BTreeMap::entry
///
/// ```
/// 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: Option<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: Some(node::Root::new_leaf()), length: 0 };
{
let root = out_tree.root.as_mut().unwrap(); // unwrap succeeds because we just wrapped
let mut out_node = match root.node_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 out_root = BTreeMap::ensure_is_owned(&mut out_tree.root);
let mut out_node = out_root.push_internal_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 subtree = ManuallyDrop::new(subtree);
let root = ptr::read(&subtree.root);
let length = subtree.length;
(root, length)
};
out_node.push(k, v, subroot.unwrap_or_else(node::Root::new_leaf));
out_tree.length += 1 + sublength;
}
}
out_tree
}
}
}
if self.is_empty() {
// Ideally we'd call `BTreeMap::new` here, but that has the `K:
// Ord` constraint, which this method lacks.
BTreeMap { root: None, length: 0 }
} else {
clone_subtree(self.root.as_ref().unwrap().node_as_ref()) // unwrap succeeds because not empty
}
}
}
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> {
let root_node = self.root.as_ref()?.node_as_ref();
match search::search_tree(root_node, key) {
Found(handle) => Some(handle.into_kv().0),
GoDown(_) => None,
}
}
fn take(&mut self, key: &Q) -> Option<K> {
let (map, dormant_map) = DormantMutRef::new(self);
let root_node = map.root.as_mut()?.node_as_mut();
match search::search_tree(root_node, key) {
Found(handle) => {
Some(OccupiedEntry { handle, dormant_map, _marker: PhantomData }.remove_kv().0)
}
GoDown(_) => None,
}
}
fn replace(&mut self, key: K) -> Option<K> {
let (map, dormant_map) = DormantMutRef::new(self);
let root_node = Self::ensure_is_owned(&mut map.root).node_as_mut();
match search::search_tree::<marker::Mut<'_>, K, (), K>(root_node, &key) {
Found(handle) => Some(mem::replace(handle.into_key_mut(), key)),
GoDown(handle) => {
VacantEntry { key, handle, dormant_map, _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`]: BTreeMap::iter
#[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`]: BTreeMap::iter_mut
#[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`]
/// (provided by the `IntoIterator` trait). See its documentation for more.
///
/// [`into_iter`]: IntoIterator::into_iter
#[stable(feature = "rust1", since = "1.0.0")]
pub struct IntoIter<K, V> {
front: Option<Handle<NodeRef<marker::Owned, K, V, marker::Leaf>, marker::Edge>>,
back: Option<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.as_ref().map(|f| f.reborrow()),
back: self.back.as_ref().map(|b| b.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`]: BTreeMap::keys
#[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`]: BTreeMap::values
#[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`]: BTreeMap::values_mut
#[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 owning iterator over the keys of a `BTreeMap`.
///
/// This `struct` is created by the [`into_keys`] method on [`BTreeMap`].
/// See its documentation for more.
///
/// [`into_keys`]: BTreeMap::into_keys
#[unstable(feature = "map_into_keys_values", issue = "75294")]
#[derive(Debug)]
pub struct IntoKeys<K, V> {
inner: IntoIter<K, V>,
}
/// An owning iterator over the values of a `BTreeMap`.
///
/// This `struct` is created by the [`into_values`] method on [`BTreeMap`].
/// See its documentation for more.
///
/// [`into_values`]: BTreeMap::into_values
#[unstable(feature = "map_into_keys_values", issue = "75294")]
#[derive(Debug)]
pub struct IntoValues<K, V> {
inner: IntoIter<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`]: BTreeMap::range
#[stable(feature = "btree_range", since = "1.17.0")]
pub struct Range<'a, K: 'a, V: 'a> {
front: Option<Handle<NodeRef<marker::Immut<'a>, K, V, marker::Leaf>, marker::Edge>>,
back: Option<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`]: BTreeMap::range_mut
#[stable(feature = "btree_range", since = "1.17.0")]
pub struct RangeMut<'a, K: 'a, V: 'a> {
front: Option<Handle<NodeRef<marker::ValMut<'a>, K, V, marker::Leaf>, marker::Edge>>,
back: Option<Handle<NodeRef<marker::ValMut<'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.as_ref().map(|f| f.reborrow()),
back: self.back.as_ref().map(|b| b.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`].
///
/// [`entry`]: BTreeMap::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.
#[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>,
dormant_map: DormantMutRef<'a, BTreeMap<K, V>>,
// 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.
#[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>,
dormant_map: DormantMutRef<'a, BTreeMap<K, V>>,
// 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.
///
/// Does not allocate anything on its own.
///
/// # 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")]
#[rustc_const_unstable(feature = "const_btree_new", issue = "71835")]
pub const fn new() -> BTreeMap<K, V> {
BTreeMap { root: None, length: 0 }
}
/// Clears the map, removing all elements.
///
/// # 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,
{
let root_node = self.root.as_ref()?.node_as_ref();
match search::search_tree(root_node, 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
///
/// ```
/// 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);
/// ```
#[stable(feature = "map_get_key_value", since = "1.40.0")]
pub fn get_key_value<Q: ?Sized>(&self, k: &Q) -> Option<(&K, &V)>
where
K: Borrow<Q>,
Q: Ord,
{
let root_node = self.root.as_ref()?.node_as_ref();
match search::search_tree(root_node, k) {
Found(handle) => Some(handle.into_kv()),
GoDown(_) => None,
}
}
/// Returns the first key-value pair in the map.
/// The key in this pair is the minimum key in the map.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(map_first_last)]
/// use std::collections::BTreeMap;
///
/// let mut map = BTreeMap::new();
/// assert_eq!(map.first_key_value(), None);
/// map.insert(1, "b");
/// map.insert(2, "a");
/// assert_eq!(map.first_key_value(), Some((&1, &"b")));
/// ```
#[unstable(feature = "map_first_last", issue = "62924")]
pub fn first_key_value(&self) -> Option<(&K, &V)> {
let root_node = self.root.as_ref()?.node_as_ref();
root_node.first_leaf_edge().right_kv().ok().map(Handle::into_kv)
}
/// Returns the first entry in the map for in-place manipulation.
/// The key of this entry is the minimum key in the map.
///
/// # Examples
///
/// ```
/// #![feature(map_first_last)]
/// use std::collections::BTreeMap;
///
/// let mut map = BTreeMap::new();
/// map.insert(1, "a");
/// map.insert(2, "b");
/// if let Some(mut entry) = map.first_entry() {
/// if *entry.key() > 0 {
/// entry.insert("first");
/// }
/// }
/// assert_eq!(*map.get(&1).unwrap(), "first");
/// assert_eq!(*map.get(&2).unwrap(), "b");
/// ```
#[unstable(feature = "map_first_last", issue = "62924")]
pub fn first_entry(&mut self) -> Option<OccupiedEntry<'_, K, V>> {
let (map, dormant_map) = DormantMutRef::new(self);
let root_node = map.root.as_mut()?.node_as_mut();
let kv = root_node.first_leaf_edge().right_kv().ok()?;
Some(OccupiedEntry { handle: kv.forget_node_type(), dormant_map, _marker: PhantomData })
}
/// Removes and returns the first element in the map.
/// The key of this element is the minimum key that was in the map.
///
/// # Examples
///
/// Draining elements in ascending order, while keeping a usable map each iteration.
///
/// ```
/// #![feature(map_first_last)]
/// use std::collections::BTreeMap;
///
/// let mut map = BTreeMap::new();
/// map.insert(1, "a");
/// map.insert(2, "b");
/// while let Some((key, _val)) = map.pop_first() {
/// assert!(map.iter().all(|(k, _v)| *k > key));
/// }
/// assert!(map.is_empty());
/// ```
#[unstable(feature = "map_first_last", issue = "62924")]
pub fn pop_first(&mut self) -> Option<(K, V)> {
self.first_entry().map(|entry| entry.remove_entry())
}
/// Returns the last key-value pair in the map.
/// The key in this pair is the maximum key in the map.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(map_first_last)]
/// use std::collections::BTreeMap;
///
/// let mut map = BTreeMap::new();
/// map.insert(1, "b");
/// map.insert(2, "a");
/// assert_eq!(map.last_key_value(), Some((&2, &"a")));
/// ```
#[unstable(feature = "map_first_last", issue = "62924")]
pub fn last_key_value(&self) -> Option<(&K, &V)> {
let root_node = self.root.as_ref()?.node_as_ref();
root_node.last_leaf_edge().left_kv().ok().map(Handle::into_kv)
}
/// Returns the last entry in the map for in-place manipulation.
/// The key of this entry is the maximum key in the map.
///
/// # Examples
///
/// ```
/// #![feature(map_first_last)]
/// use std::collections::BTreeMap;
///
/// let mut map = BTreeMap::new();
/// map.insert(1, "a");
/// map.insert(2, "b");
/// if let Some(mut entry) = map.last_entry() {
/// if *entry.key() > 0 {
/// entry.insert("last");
/// }
/// }
/// assert_eq!(*map.get(&1).unwrap(), "a");
/// assert_eq!(*map.get(&2).unwrap(), "last");
/// ```
#[unstable(feature = "map_first_last", issue = "62924")]
pub fn last_entry(&mut self) -> Option<OccupiedEntry<'_, K, V>> {
let (map, dormant_map) = DormantMutRef::new(self);
let root_node = map.root.as_mut()?.node_as_mut();
let kv = root_node.last_leaf_edge().left_kv().ok()?;
Some(OccupiedEntry { handle: kv.forget_node_type(), dormant_map, _marker: PhantomData })
}
/// Removes and returns the last element in the map.
/// The key of this element is the maximum key that was in the map.
///
/// # Examples
///
/// Draining elements in descending order, while keeping a usable map each iteration.
///
/// ```
/// #![feature(map_first_last)]
/// use std::collections::BTreeMap;
///
/// let mut map = BTreeMap::new();
/// map.insert(1, "a");
/// map.insert(2, "b");
/// while let Some((key, _val)) = map.pop_last() {
/// assert!(map.iter().all(|(k, _v)| *k < key));
/// }
/// assert!(map.is_empty());
/// ```
#[unstable(feature = "map_first_last", issue = "62924")]
pub fn pop_last(&mut self) -> Option<(K, V)> {
self.last_entry().map(|entry| entry.remove_entry())
}
/// 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,
{
let root_node = self.root.as_mut()?.node_as_mut();
match search::search_tree(root_node, key) {
Found(handle) => Some(handle.into_val_mut()),
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]: crate::collections#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,
{
self.remove_entry(key).map(|(_, v)| v)
}
/// Removes a key from the map, returning the stored key and value 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_entry(&1), Some((1, "a")));
/// assert_eq!(map.remove_entry(&1), None);
/// ```
#[stable(feature = "btreemap_remove_entry", since = "1.45.0")]
pub fn remove_entry<Q: ?Sized>(&mut self, key: &Q) -> Option<(K, V)>
where
K: Borrow<Q>,
Q: Ord,
{
let (map, dormant_map) = DormantMutRef::new(self);
let root_node = map.root.as_mut()?.node_as_mut();
match search::search_tree(root_node, key) {
Found(handle) => {
Some(OccupiedEntry { handle, dormant_map, _marker: PhantomData }.remove_entry())
}
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.is_empty() {
return;
}
// We can just swap `self` and `other` if `self` is empty.
if self.is_empty() {
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);
}
/// 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>,
{
if let Some(root) = &self.root {
let (f, b) = root.node_as_ref().range_search(range);
Range { front: Some(f), back: Some(b) }
} else {
Range { front: None, back: None }
}
}
/// 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>,
{
if let Some(root) = &mut self.root {
let (f, b) = root.node_as_valmut().range_search(range);
RangeMut { front: Some(f), back: Some(b), _marker: PhantomData }
} else {
RangeMut { front: None, back: None, _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
let (map, dormant_map) = DormantMutRef::new(self);
let root_node = Self::ensure_is_owned(&mut map.root).node_as_mut();
match search::search_tree(root_node, &key) {
Found(handle) => Occupied(OccupiedEntry { handle, dormant_map, _marker: PhantomData }),
GoDown(handle) => {
Vacant(VacantEntry { key, handle, dormant_map, _marker: PhantomData })
}
}
}
fn from_sorted_iter<I: Iterator<Item = (K, V)>>(&mut self, iter: I) {
let root = Self::ensure_is_owned(&mut self.root);
let mut cur_node = root.node_as_mut().last_leaf_edge().into_node();
// Iterate through all key-value pairs, pushing them into nodes at the right level.
for (key, value) in iter {
// Try to push key-value pair into the current leaf node.
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(_) => {
// We are at the top, create a new root node and push there.
open_node = root.push_internal_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_internal_level();
}
open_node.push(key, value, right_tree);
// Go down to the right-most leaf again.
cur_node = open_node.forget_type().last_leaf_edge().into_node();
}
self.length += 1;
}
Self::fix_right_edge(root)
}
fn fix_right_edge(root: &mut node::Root<K, V>) {
// Handle underfull nodes, start from the top.
let mut cur_node = root.node_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 left_root = self.root.as_mut().unwrap(); // unwrap succeeds because not empty
let mut right = Self::new();
let right_root = Self::ensure_is_owned(&mut right.root);
for _ in 0..left_root.height() {
right_root.push_internal_level();
}
{
let mut left_node = left_root.node_as_mut();
let mut right_node = right_root.node_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!();
}
}
}
}
left_root.fix_right_border();
right_root.fix_left_border();
if left_root.height() < right_root.height() {
self.length = left_root.node_as_ref().calc_length();
right.length = total_num - self.len();
} else {
right.length = right_root.node_as_ref().calc_length();
self.length = total_num - right.len();
}
right
}
/// Creates an iterator which uses a closure to determine if an element should be removed.
///
/// If the closure returns true, the element is removed from the map and yielded.
/// If the closure returns false, or panics, the element remains in the map and will not be
/// yielded.
///
/// Note that `drain_filter` lets you mutate every value in the filter closure, regardless of
/// whether you choose to keep or remove it.
///
/// If the iterator is only partially consumed or not consumed at all, each of the remaining
/// elements will still be subjected to the closure and removed and dropped if it returns true.
///
/// It is unspecified how many more elements will be subjected to the closure
/// if a panic occurs in the closure, or a panic occurs while dropping an element,
/// or if the `DrainFilter` value is leaked.
///
/// # Examples
///
/// Splitting a map into even and odd keys, reusing the original map:
///
/// ```
/// #![feature(btree_drain_filter)]
/// use std::collections::BTreeMap;
///
/// let mut map: BTreeMap<i32, i32> = (0..8).map(|x| (x, x)).collect();
/// let evens: BTreeMap<_, _> = map.drain_filter(|k, _v| k % 2 == 0).collect();
/// let odds = map;
/// assert_eq!(evens.keys().copied().collect::<Vec<_>>(), vec![0, 2, 4, 6]);
/// assert_eq!(odds.keys().copied().collect::<Vec<_>>(), vec![1, 3, 5, 7]);
/// ```
#[unstable(feature = "btree_drain_filter", issue = "70530")]
pub fn drain_filter<F>(&mut self, pred: F) -> DrainFilter<'_, K, V, F>
where
F: FnMut(&K, &mut V) -> bool,
{
DrainFilter { pred, inner: self.drain_filter_inner() }
}
pub(super) fn drain_filter_inner(&mut self) -> DrainFilterInner<'_, K, V> {
if let Some(root) = self.root.as_mut() {
let (root, dormant_root) = DormantMutRef::new(root);
let front = root.node_as_mut().first_leaf_edge();
DrainFilterInner {
length: &mut self.length,
dormant_root: Some(dormant_root),
cur_leaf_edge: Some(front),
}
} else {
DrainFilterInner { length: &mut self.length, dormant_root: None, cur_leaf_edge: None }
}
}
/// Creates a consuming iterator visiting all the keys, in sorted order.
/// The map cannot be used after calling this.
/// The iterator element type is `K`.
///
/// # Examples
///
/// ```
/// #![feature(map_into_keys_values)]
/// use std::collections::BTreeMap;
///
/// let mut a = BTreeMap::new();
/// a.insert(2, "b");
/// a.insert(1, "a");
///
/// let keys: Vec<i32> = a.into_keys().collect();
/// assert_eq!(keys, [1, 2]);
/// ```
#[inline]
#[unstable(feature = "map_into_keys_values", issue = "75294")]
pub fn into_keys(self) -> IntoKeys<K, V> {
IntoKeys { inner: self.into_iter() }
}
/// Creates a consuming iterator visiting all the values, in order by key.
/// The map cannot be used after calling this.
/// The iterator element type is `V`.
///
/// # Examples
///
/// ```
/// #![feature(map_into_keys_values)]
/// use std::collections::BTreeMap;
///
/// let mut a = BTreeMap::new();
/// a.insert(1, "hello");
/// a.insert(2, "goodbye");
///
/// let values: Vec<&str> = a.into_values().collect();
/// assert_eq!(values, ["hello", "goodbye"]);
/// ```
#[inline]
#[unstable(feature = "map_into_keys_values", issue = "75294")]
pub fn into_values(self) -> IntoValues<K, V> {
IntoValues { inner: self.into_iter() }
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K, V> 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()
}
fn min(mut self) -> Option<(&'a K, &'a V)> {
self.next()
}
fn max(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, V> 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;
let (k, v) = unsafe { self.range.next_unchecked() };
Some((k, v)) // coerce k from `&mut K` to `&K`
}
}
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()
}
fn min(mut self) -> Option<(&'a K, &'a mut V)> {
self.next()
}
fn max(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;
let (k, v) = unsafe { self.range.next_back_unchecked() };
Some((k, v)) // coerce k from `&mut K` to `&K`
}
}
}
#[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 mut me = ManuallyDrop::new(self);
if let Some(root) = me.root.take() {
let (f, b) = root.into_ref().full_range();
IntoIter { front: Some(f), back: Some(b), length: me.length }
} else {
IntoIter { front: None, back: None, length: 0 }
}
}
}
#[stable(feature = "btree_drop", since = "1.7.0")]
impl<K, V> Drop for IntoIter<K, V> {
fn drop(&mut self) {
struct DropGuard<'a, K, V>(&'a mut IntoIter<K, V>);
impl<'a, K, V> Drop for DropGuard<'a, K, V> {
fn drop(&mut self) {
// Continue the same loop we perform below. This only runs when unwinding, so we
// don't have to care about panics this time (they'll abort).
while let Some(_) = self.0.next() {}
unsafe {
let mut node =
unwrap_unchecked(ptr::read(&self.0.front)).into_node().forget_type();
while let Some(parent) = node.deallocate_and_ascend() {
node = parent.into_node().forget_type();
}
}
}
}
while let Some(pair) = self.next() {
let guard = DropGuard(self);
drop(pair);
mem::forget(guard);
}
unsafe {
if let Some(front) = ptr::read(&self.front) {
let mut node = front.into_node().forget_type();
// Most of the nodes have been deallocated while traversing
// but one pile from a leaf up to the root is left standing.
while let Some(parent) = node.deallocate_and_ascend() {
node = parent.into_node().forget_type();
}
}
}
}
}
#[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 {
None
} else {
self.length -= 1;
Some(unsafe { self.front.as_mut().unwrap().next_unchecked() })
}
}
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 {
None
} else {
self.length -= 1;
Some(unsafe { self.back.as_mut().unwrap().next_back_unchecked() })
}
}
}
#[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()
}
fn min(mut self) -> Option<&'a K> {
self.next()
}
fn max(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() }
}
}
/// An iterator produced by calling `drain_filter` on BTreeMap.
#[unstable(feature = "btree_drain_filter", issue = "70530")]
pub struct DrainFilter<'a, K, V, F>
where
K: 'a,
V: 'a,
F: 'a + FnMut(&K, &mut V) -> bool,
{
pred: F,
inner: DrainFilterInner<'a, K, V>,
}
/// Most of the implementation of DrainFilter, independent of the type
/// of the predicate, thus also serving for BTreeSet::DrainFilter.
pub(super) struct DrainFilterInner<'a, K: 'a, V: 'a> {
length: &'a mut usize,
// dormant_root is wrapped in an Option to be able to `take` it.
dormant_root: Option<DormantMutRef<'a, node::Root<K, V>>>,
// cur_leaf_edge is wrapped in an Option because maps without root lack a leaf edge.
cur_leaf_edge: Option<Handle<NodeRef<marker::Mut<'a>, K, V, marker::Leaf>, marker::Edge>>,
}
#[unstable(feature = "btree_drain_filter", issue = "70530")]
impl<K, V, F> Drop for DrainFilter<'_, K, V, F>
where
F: FnMut(&K, &mut V) -> bool,
{
fn drop(&mut self) {
self.for_each(drop);
}
}
#[unstable(feature = "btree_drain_filter", issue = "70530")]
impl<K, V, F> fmt::Debug for DrainFilter<'_, K, V, F>
where
K: fmt::Debug,
V: fmt::Debug,
F: FnMut(&K, &mut V) -> bool,
{
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_tuple("DrainFilter").field(&self.inner.peek()).finish()
}
}
#[unstable(feature = "btree_drain_filter", issue = "70530")]
impl<K, V, F> Iterator for DrainFilter<'_, K, V, F>
where
F: FnMut(&K, &mut V) -> bool,
{
type Item = (K, V);
fn next(&mut self) -> Option<(K, V)> {
self.inner.next(&mut self.pred)
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.inner.size_hint()
}
}
impl<'a, K: 'a, V: 'a> DrainFilterInner<'a, K, V> {
/// Allow Debug implementations to predict the next element.
pub(super) fn peek(&self) -> Option<(&K, &V)> {
let edge = self.cur_leaf_edge.as_ref()?;
edge.reborrow().next_kv().ok().map(Handle::into_kv)
}
/// Implementation of a typical `DrainFilter::next` method, given the predicate.
pub(super) fn next<F>(&mut self, pred: &mut F) -> Option<(K, V)>
where
F: FnMut(&K, &mut V) -> bool,
{
while let Ok(mut kv) = self.cur_leaf_edge.take()?.next_kv() {
let (k, v) = kv.kv_mut();
if pred(k, v) {
*self.length -= 1;
let (kv, pos) = kv.remove_kv_tracking(|| {
// SAFETY: we will touch the root in a way that will not
// invalidate the position returned.
let root = unsafe { self.dormant_root.take().unwrap().awaken() };
root.pop_internal_level();
self.dormant_root = Some(DormantMutRef::new(root).1);
});
self.cur_leaf_edge = Some(pos);
return Some(kv);
}
self.cur_leaf_edge = Some(kv.next_leaf_edge());
}
None
}
/// Implementation of a typical `DrainFilter::size_hint` method.
pub(super) fn size_hint(&self) -> (usize, Option<usize>) {
(0, Some(*self.length))
}
}
#[unstable(feature = "btree_drain_filter", issue = "70530")]
impl<K, V, F> FusedIterator for DrainFilter<'_, K, V, F> where F: FnMut(&K, &mut V) -> bool {}
#[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.is_empty() { None } else { unsafe { Some(self.next_unchecked()) } }
}
fn last(mut self) -> Option<(&'a K, &'a V)> {
self.next_back()
}
fn min(mut self) -> Option<(&'a K, &'a V)> {
self.next()
}
fn max(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> {
fn is_empty(&self) -> bool {
self.front == self.back
}
unsafe fn next_unchecked(&mut self) -> (&'a K, &'a V) {
unsafe { unwrap_unchecked(self.front.as_mut()).next_unchecked() }
}
}
#[unstable(feature = "map_into_keys_values", issue = "75294")]
impl<K, V> Iterator for IntoKeys<K, V> {
type Item = K;
fn next(&mut self) -> Option<K> {
self.inner.next().map(|(k, _)| k)
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.inner.size_hint()
}
fn last(mut self) -> Option<K> {
self.next_back()
}
fn min(mut self) -> Option<K> {
self.next()
}
fn max(mut self) -> Option<K> {
self.next_back()
}
}
#[unstable(feature = "map_into_keys_values", issue = "75294")]
impl<K, V> DoubleEndedIterator for IntoKeys<K, V> {
fn next_back(&mut self) -> Option<K> {
self.inner.next_back().map(|(k, _)| k)
}
}
#[unstable(feature = "map_into_keys_values", issue = "75294")]
impl<K, V> ExactSizeIterator for IntoKeys<K, V> {
fn len(&self) -> usize {
self.inner.len()
}
}
#[unstable(feature = "map_into_keys_values", issue = "75294")]
impl<K, V> FusedIterator for IntoKeys<K, V> {}
#[unstable(feature = "map_into_keys_values", issue = "75294")]
impl<K, V> Iterator for IntoValues<K, V> {
type Item = V;
fn next(&mut self) -> Option<V> {
self.inner.next().map(|(_, v)| v)
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.inner.size_hint()
}
fn last(mut self) -> Option<V> {
self.next_back()
}
}
#[unstable(feature = "map_into_keys_values", issue = "75294")]
impl<K, V> DoubleEndedIterator for IntoValues<K, V> {
fn next_back(&mut self) -> Option<V> {
self.inner.next_back().map(|(_, v)| v)
}
}
#[unstable(feature = "map_into_keys_values", issue = "75294")]
impl<K, V> ExactSizeIterator for IntoValues<K, V> {
fn len(&self) -> usize {
self.inner.len()
}
}
#[unstable(feature = "map_into_keys_values", issue = "75294")]
impl<K, V> FusedIterator for IntoValues<K, V> {}
#[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.is_empty() { None } else { Some(unsafe { self.next_back_unchecked() }) }
}
}
impl<'a, K, V> Range<'a, K, V> {
unsafe fn next_back_unchecked(&mut self) -> (&'a K, &'a V) {
unsafe { unwrap_unchecked(self.back.as_mut()).next_back_unchecked() }
}
}
#[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.is_empty() {
None
} else {
let (k, v) = unsafe { self.next_unchecked() };
Some((k, v)) // coerce k from `&mut K` to `&K`
}
}
fn last(mut self) -> Option<(&'a K, &'a mut V)> {
self.next_back()
}
fn min(mut self) -> Option<(&'a K, &'a mut V)> {
self.next()
}
fn max(mut self) -> Option<(&'a K, &'a mut V)> {
self.next_back()
}
}
impl<'a, K, V> RangeMut<'a, K, V> {
fn is_empty(&self) -> bool {
self.front == self.back
}
unsafe fn next_unchecked(&mut self) -> (&'a K, &'a mut V) {
unsafe { unwrap_unchecked(self.front.as_mut()).next_unchecked() }
}
}
#[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.is_empty() {
None
} else {
let (k, v) = unsafe { self.next_back_unchecked() };
Some((k, v)) // coerce k from `&mut K` to `&K`
}
}
}
#[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) {
unsafe { unwrap_unchecked(self.back.as_mut()).next_back_unchecked() }
}
}
#[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);
});
}
#[inline]
fn extend_one(&mut self, (k, v): (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)));
}
#[inline]
fn extend_one(&mut self, (&k, &v): (&'a K, &'a V)) {
self.insert(k, v);
}
}
#[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")
}
}
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> {
if let Some(root) = &self.root {
let (f, b) = root.node_as_ref().full_range();
Iter { range: Range { front: Some(f), back: Some(b) }, length: self.length }
} else {
Iter { range: Range { front: None, back: None }, length: 0 }
}
}
/// 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> {
if let Some(root) = &mut self.root {
let (f, b) = root.node_as_valmut().full_range();
IterMut {
range: RangeMut { front: Some(f), back: Some(b), _marker: PhantomData },
length: self.length,
}
} else {
IterMut { range: RangeMut { front: None, back: None, _marker: PhantomData }, length: 0 }
}
}
/// 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
}
/// If the root node is the empty (non-allocated) root node, allocate our
/// own node. Is an associated function to avoid borrowing the entire BTreeMap.
fn ensure_is_owned(root: &mut Option<node::Root<K, V>>) -> &mut node::Root<K, V> {
root.get_or_insert_with(node::Root::new_leaf)
}
}
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()),
}
}
#[unstable(feature = "or_insert_with_key", issue = "71024")]
/// Ensures a value is in the entry by inserting, if empty, the result of the default function,
/// which takes the key as its argument, and returns a mutable reference to the value in the
/// entry.
///
/// # Examples
///
/// ```
/// #![feature(or_insert_with_key)]
/// use std::collections::BTreeMap;
///
/// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
///
/// map.entry("poneyland").or_insert_with_key(|key| key.chars().count());
///
/// assert_eq!(map["poneyland"], 9);
/// ```
#[inline]
pub fn or_insert_with_key<F: FnOnce(&K) -> V>(self, default: F) -> &'a mut V {
match self {
Occupied(entry) => entry.into_mut(),
Vacant(entry) => {
let value = default(entry.key());
entry.insert(value)
}
}
}
/// 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
///
/// ```
/// 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;
/// use std::collections::btree_map::Entry;
///
/// let mut map: BTreeMap<&str, u32> = BTreeMap::new();
///
/// if let Entry::Vacant(o) = map.entry("poneyland") {
/// o.insert(37);
/// }
/// assert_eq!(map["poneyland"], 37);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn insert(self, value: V) -> &'a mut V {
let out_ptr = match self.handle.insert_recursing(self.key, value) {
(Fit(_), val_ptr) => {
// Safety: We have consumed self.handle and the handle returned.
let map = unsafe { self.dormant_map.awaken() };
map.length += 1;
val_ptr
}
(Split(ins), val_ptr) => {
drop(ins.left);
// Safety: We have consumed self.handle and the reference returned.
let map = unsafe { self.dormant_map.awaken() };
let root = map.root.as_mut().unwrap();
root.push_internal_level().push(ins.k, ins.v, ins.right);
map.length += 1;
val_ptr
}
};
// Now that we have finished growing the tree using borrowed references,
// dereference the pointer to a part of it, that we picked up along the way.
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`]: OccupiedEntry::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`]: OccupiedEntry::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_val_mut()
}
/// 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
}
// Body of `remove_entry`, separate to keep the above implementations short.
fn remove_kv(self) -> (K, V) {
let mut emptied_internal_root = false;
let (old_kv, _) = self.handle.remove_kv_tracking(|| emptied_internal_root = true);
// SAFETY: we consumed the intermediate root borrow, `self.handle`.
let map = unsafe { self.dormant_map.awaken() };
map.length -= 1;
if emptied_internal_root {
let root = map.root.as_mut().unwrap();
root.pop_internal_level();
}
old_kv
}
}
impl<'a, K: 'a, V: 'a> Handle<NodeRef<marker::Mut<'a>, K, V, marker::LeafOrInternal>, marker::KV> {
/// Removes a key/value-pair from the map, and returns that pair, as well as
/// the leaf edge corresponding to that former pair.
fn remove_kv_tracking<F: FnOnce()>(
self,
handle_emptied_internal_root: F,
) -> ((K, V), Handle<NodeRef<marker::Mut<'a>, K, V, marker::Leaf>, marker::Edge>) {
let (old_kv, mut pos, was_internal) = match self.force() {
Leaf(leaf) => {
let (old_kv, pos) = leaf.remove();
(old_kv, pos, false)
}
Internal(mut internal) => {
// Replace the location freed in the internal node with an
// adjacent KV, and remove that adjacent KV from its leaf.
// Always choose the adjacent KV on the left side because
// it is typically faster to pop an element from the end
// of the KV arrays without needing to shift other elements.
let key_loc = internal.kv_mut().0 as *mut K;
let val_loc = internal.kv_mut().1 as *mut V;
let to_remove = internal.left_edge().descend().last_leaf_edge().left_kv().ok();
let to_remove = unsafe { unwrap_unchecked(to_remove) };
let (kv, pos) = to_remove.remove();
let old_key = unsafe { mem::replace(&mut *key_loc, kv.0) };
let old_val = unsafe { mem::replace(&mut *val_loc, kv.1) };
((old_key, old_val), pos, true)
}
};
// Handle underflow
let mut cur_node = unsafe { ptr::read(&pos).into_node().forget_type() };
let mut at_leaf = true;
while cur_node.len() < node::MIN_LEN {
match handle_underfull_node(cur_node) {
AtRoot => break,
Merged(edge, merged_with_left, offset) => {
// If we merged with our right sibling then our tracked
// position has not changed. However if we merged with our
// left sibling then our tracked position is now dangling.
if at_leaf && merged_with_left {
let idx = pos.idx() + offset;
let node = match unsafe { ptr::read(&edge).descend().force() } {
Leaf(leaf) => leaf,
Internal(_) => unreachable!(),
};
pos = unsafe { Handle::new_edge(node, idx) };
}
let parent = edge.into_node();
if parent.len() == 0 {
// The parent that was just emptied must be the root,
// because nodes on a lower level would not have been
// left with a single child.
handle_emptied_internal_root();
break;
} else {
cur_node = parent.forget_type();
at_leaf = false;
}
}
Stole(stole_from_left) => {
// Adjust the tracked position if we stole from a left sibling
if stole_from_left && at_leaf {
// SAFETY: This is safe since we just added an element to our node.
unsafe {
pos.move_next_unchecked();
}
}
break;
}
}
}
// If we deleted from an internal node then we need to compensate for
// the earlier swap and adjust the tracked position to point to the
// next element.
if was_internal {
pos = unsafe { unwrap_unchecked(pos.next_kv().ok()).next_leaf_edge() };
}
(old_kv, pos)
}
}
impl<K, V> node::Root<K, V> {
/// Removes empty levels on the top, but keep an empty leaf if the entire tree is empty.
fn fix_top(&mut self) {
while self.height() > 0 && self.node_as_ref().len() == 0 {
self.pop_internal_level();
}
}
fn fix_right_border(&mut self) {
self.fix_top();
{
let mut cur_node = self.node_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.node_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();
}
}
enum UnderflowResult<'a, K, V> {
AtRoot,
Merged(Handle<NodeRef<marker::Mut<'a>, K, V, marker::Internal>, marker::Edge>, bool, usize),
Stole(bool),
}
fn handle_underfull_node<'a, K: 'a, V: 'a>(
node: NodeRef<marker::Mut<'a>, K, V, marker::LeafOrInternal>,
) -> UnderflowResult<'_, K, V> {
let parent = match node.ascend() {
Ok(parent) => parent,
Err(_) => return AtRoot,
};
// Prefer the left KV if it exists. Merging with the left side is faster,
// since merging happens towards the left and `node` has fewer elements.
// Stealing from the left side is faster, since we can pop from the end of
// the KV arrays.
let (is_left, mut handle) = match parent.left_kv() {
Ok(left) => (true, left),
Err(parent) => {
let right = unsafe { unwrap_unchecked(parent.right_kv().ok()) };
(false, right)
}
};
if handle.can_merge() {
let offset = if is_left { handle.reborrow().left_edge().descend().len() + 1 } else { 0 };
Merged(handle.merge(), is_left, offset)
} else {
if is_left {
handle.steal_left();
} else {
handle.steal_right();
}
Stole(is_left)
}
}
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()
}
}
}
}
#[cfg(test)]
mod tests;