Google Git
Sign in
nest-open-source / manifest_repos / toolchain / 6143c57c644e0da7c4a10d1b4af322f92e74e6f7 / . / x86_64 / usr / lib / rustlib / src / rust / library / alloc / src / collections / btree / map.rs
blob: 1d9c4460ec92a9537f9b7cf8c86a634cc7829474 [file] [log] [blame]
use crate::vec::Vec;
use core::borrow::Borrow;
use core::cmp::Ordering;
use core::fmt::{self, Debug};
use core::hash::{Hash, Hasher};
use core::iter::{FromIterator, FusedIterator};
use core::marker::PhantomData;
use core::mem::{self, ManuallyDrop};
use core::ops::{Index, RangeBounds};
use core::ptr;
use crate::alloc::{Allocator, Global};
use super::borrow::DormantMutRef;
use super::dedup_sorted_iter::DedupSortedIter;
use super::navigate::{LazyLeafRange, LeafRange};
use super::node::{self, marker, ForceResult::*, Handle, NodeRef, Root};
use super::search::SearchResult::*;
use super::set_val::SetValZST;
mod entry;
#[stable(feature = "rust1", since = "1.0.0")]
pub use entry::{Entry, OccupiedEntry, OccupiedError, VacantEntry};
use Entry::*;
/// Minimum number of elements in a node that is not a root.
/// We might temporarily have fewer elements during methods.
pub(super) const MIN_LEN: usize = node::MIN_LEN_AFTER_SPLIT;
// A tree in a `BTreeMap` is a tree in the `node` module with additional invariants:
// - Keys must appear in ascending order (according to the key's type).
// - Every non-leaf node contains at least 1 element (has at least 2 children).
// - Every non-root node contains at least MIN_LEN elements.
//
// An empty map is represented either by the absence of a root node or by a
// root node that is an empty leaf.
/// An ordered 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 the 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 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.
/// The behavior resulting from such a logic error is not specified, but will be encapsulated to the
/// `BTreeMap` that observed the logic error and not result in undefined behavior. This could
/// include panics, incorrect results, aborts, memory leaks, and non-termination.
///
/// Iterators obtained from functions such as [`BTreeMap::iter`], [`BTreeMap::values`], or
/// [`BTreeMap::keys`] produce their items in order by key, and take worst-case logarithmic and
/// amortized constant time per item returned.
///
/// [B-Tree]: https://en.wikipedia.org/wiki/B-tree
/// [`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!("{movie} is unreviewed.")
/// }
/// }
///
/// // 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}\"");
/// }
/// ```
///
/// A `BTreeMap` with a known list of items can be initialized from an array:
///
/// ```
/// use std::collections::BTreeMap;
///
/// let solar_distance = BTreeMap::from([
/// ("Mercury", 0.4),
/// ("Venus", 0.7),
/// ("Earth", 1.0),
/// ("Mars", 1.5),
/// ]);
/// ```
///
/// `BTreeMap` implements an [`Entry API`], which allows for 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();
///
/// // modify an entry before an insert with in-place mutation
/// player_stats.entry("mana").and_modify(|mana| *mana += 200).or_insert(100);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[cfg_attr(not(test), rustc_diagnostic_item = "BTreeMap")]
#[rustc_insignificant_dtor]
pub struct BTreeMap<
K,
V,
#[unstable(feature = "allocator_api", issue = "32838")] A: Allocator + Clone = Global,
> {
root: Option<Root<K, V>>,
length: usize,
/// `ManuallyDrop` to control drop order (needs to be dropped after all the nodes).
pub(super) alloc: ManuallyDrop<A>,
// For dropck; the `Box` avoids making the `Unpin` impl more strict than before
_marker: PhantomData<crate::boxed::Box<(K, V)>>,
}
#[stable(feature = "btree_drop", since = "1.7.0")]
unsafe impl<#[may_dangle] K, #[may_dangle] V, A: Allocator + Clone> Drop for BTreeMap<K, V, A> {
fn drop(&mut self) {
drop(unsafe { ptr::read(self) }.into_iter())
}
}
// FIXME: This implementation is "wrong", but changing it would be a breaking change.
// (The bounds of the automatic `UnwindSafe` implementation have been like this since Rust 1.50.)
// Maybe we can fix it nonetheless with a crater run, or if the `UnwindSafe`
// traits are deprecated, or disarmed (no longer causing hard errors) in the future.
#[stable(feature = "btree_unwindsafe", since = "1.64.0")]
impl<K, V, A: Allocator + Clone> core::panic::UnwindSafe for BTreeMap<K, V, A>
where
A: core::panic::UnwindSafe,
K: core::panic::RefUnwindSafe,
V: core::panic::RefUnwindSafe,
{
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K: Clone, V: Clone, A: Allocator + Clone> Clone for BTreeMap<K, V, A> {
fn clone(&self) -> BTreeMap<K, V, A> {
fn clone_subtree<'a, K: Clone, V: Clone, A: Allocator + Clone>(
node: NodeRef<marker::Immut<'a>, K, V, marker::LeafOrInternal>,
alloc: A,
) -> BTreeMap<K, V, A>
where
K: 'a,
V: 'a,
{
match node.force() {
Leaf(leaf) => {
let mut out_tree = BTreeMap {
root: Some(Root::new(alloc.clone())),
length: 0,
alloc: ManuallyDrop::new(alloc),
_marker: PhantomData,
};
{
let root = out_tree.root.as_mut().unwrap(); // unwrap succeeds because we just wrapped
let mut out_node = match root.borrow_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(), alloc.clone());
{
let out_root = out_tree.root.as_mut().unwrap();
let mut out_node = out_root.push_internal_level(alloc.clone());
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(), alloc.clone());
// 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(|| Root::new(alloc.clone())),
);
out_tree.length += 1 + sublength;
}
}
out_tree
}
}
}
if self.is_empty() {
BTreeMap::new_in((*self.alloc).clone())
} else {
clone_subtree(self.root.as_ref().unwrap().reborrow(), (*self.alloc).clone()) // unwrap succeeds because not empty
}
}
}
impl<K, Q: ?Sized, A: Allocator + Clone> super::Recover<Q> for BTreeMap<K, SetValZST, A>
where
K: Borrow<Q> + Ord,
Q: Ord,
{
type Key = K;
fn get(&self, key: &Q) -> Option<&K> {
let root_node = self.root.as_ref()?.reborrow();
match root_node.search_tree(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()?.borrow_mut();
match root_node.search_tree(key) {
Found(handle) => Some(
OccupiedEntry {
handle,
dormant_map,
alloc: (*map.alloc).clone(),
_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 =
map.root.get_or_insert_with(|| Root::new((*map.alloc).clone())).borrow_mut();
match root_node.search_tree::<K>(&key) {
Found(mut kv) => Some(mem::replace(kv.key_mut(), key)),
GoDown(handle) => {
VacantEntry {
key,
handle: Some(handle),
dormant_map,
alloc: (*map.alloc).clone(),
_marker: PhantomData,
}
.insert(SetValZST::default());
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
#[must_use = "iterators are lazy and do nothing unless consumed"]
#[stable(feature = "rust1", since = "1.0.0")]
pub struct Iter<'a, K: 'a, V: 'a> {
range: LazyLeafRange<marker::Immut<'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")]
pub struct IterMut<'a, K: 'a, V: 'a> {
range: LazyLeafRange<marker::ValMut<'a>, K, V>,
length: usize,
// Be invariant in `K` and `V`
_marker: PhantomData<&'a mut (K, V)>,
}
#[must_use = "iterators are lazy and do nothing unless consumed"]
#[stable(feature = "collection_debug", since = "1.17.0")]
impl<K: fmt::Debug, V: fmt::Debug> fmt::Debug for IterMut<'_, K, V> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let range = Iter { range: self.range.reborrow(), length: self.length };
f.debug_list().entries(range).finish()
}
}
/// 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
/// [`IntoIterator`]: core::iter::IntoIterator
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_insignificant_dtor]
pub struct IntoIter<
K,
V,
#[unstable(feature = "allocator_api", issue = "32838")] A: Allocator + Clone = Global,
> {
range: LazyLeafRange<marker::Dying, K, V>,
length: usize,
/// The BTreeMap will outlive this IntoIter so we don't care about drop order for `alloc`.
alloc: A,
}
impl<K, V, A: Allocator + Clone> IntoIter<K, V, A> {
/// Returns an iterator of references over the remaining items.
#[inline]
pub(super) fn iter(&self) -> Iter<'_, K, V> {
Iter { range: self.range.reborrow(), length: self.length }
}
}
#[stable(feature = "collection_debug", since = "1.17.0")]
impl<K: Debug, V: Debug, A: Allocator + Clone> Debug for IntoIter<K, V, A> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_list().entries(self.iter()).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
#[must_use = "iterators are lazy and do nothing unless consumed"]
#[stable(feature = "rust1", since = "1.0.0")]
pub struct Keys<'a, K, V> {
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
#[must_use = "iterators are lazy and do nothing unless consumed"]
#[stable(feature = "rust1", since = "1.0.0")]
pub struct Values<'a, K, V> {
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
#[must_use = "iterators are lazy and do nothing unless consumed"]
#[stable(feature = "map_values_mut", since = "1.10.0")]
pub struct ValuesMut<'a, K, V> {
inner: IterMut<'a, K, V>,
}
#[stable(feature = "map_values_mut", since = "1.10.0")]
impl<K, V: fmt::Debug> fmt::Debug for ValuesMut<'_, K, V> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_list().entries(self.inner.iter().map(|(_, val)| val)).finish()
}
}
/// 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
#[must_use = "iterators are lazy and do nothing unless consumed"]
#[stable(feature = "map_into_keys_values", since = "1.54.0")]
pub struct IntoKeys<K, V, A: Allocator + Clone = Global> {
inner: IntoIter<K, V, A>,
}
#[stable(feature = "map_into_keys_values", since = "1.54.0")]
impl<K: fmt::Debug, V, A: Allocator + Clone> fmt::Debug for IntoKeys<K, V, A> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_list().entries(self.inner.iter().map(|(key, _)| key)).finish()
}
}
/// 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
#[must_use = "iterators are lazy and do nothing unless consumed"]
#[stable(feature = "map_into_keys_values", since = "1.54.0")]
pub struct IntoValues<
K,
V,
#[unstable(feature = "allocator_api", issue = "32838")] A: Allocator + Clone = Global,
> {
inner: IntoIter<K, V, A>,
}
#[stable(feature = "map_into_keys_values", since = "1.54.0")]
impl<K, V: fmt::Debug, A: Allocator + Clone> fmt::Debug for IntoValues<K, V, A> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_list().entries(self.inner.iter().map(|(_, val)| val)).finish()
}
}
/// 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
#[must_use = "iterators are lazy and do nothing unless consumed"]
#[stable(feature = "btree_range", since = "1.17.0")]
pub struct Range<'a, K: 'a, V: 'a> {
inner: LeafRange<marker::Immut<'a>, K, V>,
}
#[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
#[must_use = "iterators are lazy and do nothing unless consumed"]
#[stable(feature = "btree_range", since = "1.17.0")]
pub struct RangeMut<'a, K: 'a, V: 'a> {
inner: LeafRange<marker::ValMut<'a>, K, V>,
// 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 { inner: self.inner.reborrow() };
f.debug_list().entries(range).finish()
}
}
impl<K, 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_stable(feature = "const_btree_new", since = "1.66.0")]
#[must_use]
pub const fn new() -> BTreeMap<K, V> {
BTreeMap { root: None, length: 0, alloc: ManuallyDrop::new(Global), _marker: PhantomData }
}
}
impl<K, V, A: Allocator + Clone> BTreeMap<K, V, A> {
/// 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) {
// avoid moving the allocator
mem::drop(BTreeMap {
root: mem::replace(&mut self.root, None),
length: mem::replace(&mut self.length, 0),
alloc: self.alloc.clone(),
_marker: PhantomData,
});
}
/// Makes a new empty BTreeMap with a reasonable choice for B.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// # #![feature(allocator_api)]
/// # #![feature(btreemap_alloc)]
/// use std::collections::BTreeMap;
/// use std::alloc::Global;
///
/// let mut map = BTreeMap::new_in(Global);
///
/// // entries can now be inserted into the empty map
/// map.insert(1, "a");
/// ```
#[unstable(feature = "btreemap_alloc", issue = "32838")]
pub fn new_in(alloc: A) -> BTreeMap<K, V, A> {
BTreeMap { root: None, length: 0, alloc: ManuallyDrop::new(alloc), _marker: PhantomData }
}
}
impl<K, V, A: Allocator + Clone> BTreeMap<K, V, A> {
/// 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> + Ord,
Q: Ord,
{
let root_node = self.root.as_ref()?.reborrow();
match root_node.search_tree(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> + Ord,
Q: Ord,
{
let root_node = self.root.as_ref()?.reborrow();
match root_node.search_tree(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:
///
/// ```
/// 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")));
/// ```
#[stable(feature = "map_first_last", since = "1.66.0")]
pub fn first_key_value(&self) -> Option<(&K, &V)>
where
K: Ord,
{
let root_node = self.root.as_ref()?.reborrow();
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
///
/// ```
/// 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");
/// ```
#[stable(feature = "map_first_last", since = "1.66.0")]
pub fn first_entry(&mut self) -> Option<OccupiedEntry<'_, K, V, A>>
where
K: Ord,
{
let (map, dormant_map) = DormantMutRef::new(self);
let root_node = map.root.as_mut()?.borrow_mut();
let kv = root_node.first_leaf_edge().right_kv().ok()?;
Some(OccupiedEntry {
handle: kv.forget_node_type(),
dormant_map,
alloc: (*map.alloc).clone(),
_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.
///
/// ```
/// 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());
/// ```
#[stable(feature = "map_first_last", since = "1.66.0")]
pub fn pop_first(&mut self) -> Option<(K, V)>
where
K: Ord,
{
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:
///
/// ```
/// 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")));
/// ```
#[stable(feature = "map_first_last", since = "1.66.0")]
pub fn last_key_value(&self) -> Option<(&K, &V)>
where
K: Ord,
{
let root_node = self.root.as_ref()?.reborrow();
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
///
/// ```
/// 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");
/// ```
#[stable(feature = "map_first_last", since = "1.66.0")]
pub fn last_entry(&mut self) -> Option<OccupiedEntry<'_, K, V, A>>
where
K: Ord,
{
let (map, dormant_map) = DormantMutRef::new(self);
let root_node = map.root.as_mut()?.borrow_mut();
let kv = root_node.last_leaf_edge().left_kv().ok()?;
Some(OccupiedEntry {
handle: kv.forget_node_type(),
dormant_map,
alloc: (*map.alloc).clone(),
_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.
///
/// ```
/// 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());
/// ```
#[stable(feature = "map_first_last", since = "1.66.0")]
pub fn pop_last(&mut self) -> Option<(K, V)>
where
K: Ord,
{
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> + Ord,
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> + Ord,
Q: Ord,
{
let root_node = self.root.as_mut()?.borrow_mut();
match root_node.search_tree(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]: 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>
where
K: Ord,
{
match self.entry(key) {
Occupied(mut entry) => Some(entry.insert(value)),
Vacant(entry) => {
entry.insert(value);
None
}
}
}
/// Tries to insert a key-value pair into the map, and returns
/// a mutable reference to the value in the entry.
///
/// If the map already had this key present, nothing is updated, and
/// an error containing the occupied entry and the value is returned.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(map_try_insert)]
///
/// use std::collections::BTreeMap;
///
/// let mut map = BTreeMap::new();
/// assert_eq!(map.try_insert(37, "a").unwrap(), &"a");
///
/// let err = map.try_insert(37, "b").unwrap_err();
/// assert_eq!(err.entry.key(), &37);
/// assert_eq!(err.entry.get(), &"a");
/// assert_eq!(err.value, "b");
/// ```
#[unstable(feature = "map_try_insert", issue = "82766")]
pub fn try_insert(&mut self, key: K, value: V) -> Result<&mut V, OccupiedError<'_, K, V, A>>
where
K: Ord,
{
match self.entry(key) {
Occupied(entry) => Err(OccupiedError { entry, value }),
Vacant(entry) => Ok(entry.insert(value)),
}
}
/// 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> + Ord,
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> + Ord,
Q: Ord,
{
let (map, dormant_map) = DormantMutRef::new(self);
let root_node = map.root.as_mut()?.borrow_mut();
match root_node.search_tree(key) {
Found(handle) => Some(
OccupiedEntry {
handle,
dormant_map,
alloc: (*map.alloc).clone(),
_marker: PhantomData,
}
.remove_entry(),
),
GoDown(_) => None,
}
}
/// Retains only the elements specified by the predicate.
///
/// In other words, remove all pairs `(k, v)` for which `f(&k, &mut v)` returns `false`.
/// The elements are visited in ascending key order.
///
/// # Examples
///
/// ```
/// use std::collections::BTreeMap;
///
/// let mut map: BTreeMap<i32, i32> = (0..8).map(|x| (x, x*10)).collect();
/// // Keep only the elements with even-numbered keys.
/// map.retain(|&k, _| k % 2 == 0);
/// assert!(map.into_iter().eq(vec![(0, 0), (2, 20), (4, 40), (6, 60)]));
/// ```
#[inline]
#[stable(feature = "btree_retain", since = "1.53.0")]
pub fn retain<F>(&mut self, mut f: F)
where
K: Ord,
F: FnMut(&K, &mut V) -> bool,
{
self.drain_filter(|k, v| !f(k, v));
}
/// Moves all elements from `other` into `self`, leaving `other` empty.
///
/// If a key from `other` is already present in `self`, the respective
/// value from `self` will be overwritten with the respective value from `other`.
///
/// # Examples
///
/// ```
/// use std::collections::BTreeMap;
///
/// let mut a = BTreeMap::new();
/// a.insert(1, "a");
/// a.insert(2, "b");
/// a.insert(3, "c"); // Note: Key (3) also present in b.
///
/// let mut b = BTreeMap::new();
/// b.insert(3, "d"); // Note: Key (3) also present in a.
/// 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"); // Note: "c" has been overwritten.
/// 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)
where
K: Ord,
A: Clone,
{
// 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;
}
let self_iter = mem::replace(self, Self::new_in((*self.alloc).clone())).into_iter();
let other_iter = mem::replace(other, Self::new_in((*self.alloc).clone())).into_iter();
let root = self.root.get_or_insert_with(|| Root::new((*self.alloc).clone()));
root.append_from_sorted_iters(
self_iter,
other_iter,
&mut self.length,
(*self.alloc).clone(),
)
}
/// 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> + Ord,
R: RangeBounds<T>,
{
if let Some(root) = &self.root {
Range { inner: root.reborrow().range_search(range) }
} else {
Range { inner: LeafRange::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", 0), ("Bob", 0), ("Carol", 0), ("Cheryl", 0)].into();
/// 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> + Ord,
R: RangeBounds<T>,
{
if let Some(root) = &mut self.root {
RangeMut { inner: root.borrow_valmut().range_search(range), _marker: PhantomData }
} else {
RangeMut { inner: LeafRange::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 ["a", "b", "a", "c", "a", "b"] {
/// count.entry(x).and_modify(|curr| *curr += 1).or_insert(1);
/// }
///
/// assert_eq!(count["a"], 3);
/// assert_eq!(count["b"], 2);
/// assert_eq!(count["c"], 1);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn entry(&mut self, key: K) -> Entry<'_, K, V, A>
where
K: Ord,
{
let (map, dormant_map) = DormantMutRef::new(self);
match map.root {
None => Vacant(VacantEntry {
key,
handle: None,
dormant_map,
alloc: (*map.alloc).clone(),
_marker: PhantomData,
}),
Some(ref mut root) => match root.borrow_mut().search_tree(&key) {
Found(handle) => Occupied(OccupiedEntry {
handle,
dormant_map,
alloc: (*map.alloc).clone(),
_marker: PhantomData,
}),
GoDown(handle) => Vacant(VacantEntry {
key,
handle: Some(handle),
dormant_map,
alloc: (*map.alloc).clone(),
_marker: PhantomData,
}),
},
}
}
/// 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> + Ord,
A: Clone,
{
if self.is_empty() {
return Self::new_in((*self.alloc).clone());
}
let total_num = self.len();
let left_root = self.root.as_mut().unwrap(); // unwrap succeeds because not empty
let right_root = left_root.split_off(key, (*self.alloc).clone());
let (new_left_len, right_len) = Root::calc_split_length(total_num, &left_root, &right_root);
self.length = new_left_len;
BTreeMap {
root: Some(right_root),
length: right_len,
alloc: self.alloc.clone(),
_marker: PhantomData,
}
}
/// Creates an iterator that visits all elements (key-value pairs) in
/// ascending key order and 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.
///
/// The iterator also lets you mutate the value of each element in the
/// 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 is still subjected to the closure, which may
/// change its value and, by returning `true`, have the element removed and
/// dropped.
///
/// 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<_>>(), [0, 2, 4, 6]);
/// assert_eq!(odds.keys().copied().collect::<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, A>
where
K: Ord,
F: FnMut(&K, &mut V) -> bool,
{
let (inner, alloc) = self.drain_filter_inner();
DrainFilter { pred, inner, alloc }
}
pub(super) fn drain_filter_inner(&mut self) -> (DrainFilterInner<'_, K, V>, A)
where
K: Ord,
{
if let Some(root) = self.root.as_mut() {
let (root, dormant_root) = DormantMutRef::new(root);
let front = root.borrow_mut().first_leaf_edge();
(
DrainFilterInner {
length: &mut self.length,
dormant_root: Some(dormant_root),
cur_leaf_edge: Some(front),
},
(*self.alloc).clone(),
)
} else {
(
DrainFilterInner {
length: &mut self.length,
dormant_root: None,
cur_leaf_edge: None,
},
(*self.alloc).clone(),
)
}
}
/// 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
///
/// ```
/// 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]
#[stable(feature = "map_into_keys_values", since = "1.54.0")]
pub fn into_keys(self) -> IntoKeys<K, V, A> {
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
///
/// ```
/// 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]
#[stable(feature = "map_into_keys_values", since = "1.54.0")]
pub fn into_values(self) -> IntoValues<K, V, A> {
IntoValues { inner: self.into_iter() }
}
/// Makes a `BTreeMap` from a sorted iterator.
pub(crate) fn bulk_build_from_sorted_iter<I>(iter: I, alloc: A) -> Self
where
K: Ord,
I: IntoIterator<Item = (K, V)>,
{
let mut root = Root::new(alloc.clone());
let mut length = 0;
root.bulk_push(DedupSortedIter::new(iter.into_iter()), &mut length, alloc.clone());
BTreeMap { root: Some(root), length, alloc: ManuallyDrop::new(alloc), _marker: PhantomData }
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K, V, A: Allocator + Clone> IntoIterator for &'a BTreeMap<K, V, A> {
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;
Some(unsafe { 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;
Some(unsafe { 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, A: Allocator + Clone> IntoIterator for &'a mut BTreeMap<K, V, A> {
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, V> 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;
Some(unsafe { 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()
}
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, V> 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;
Some(unsafe { 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> {}
impl<'a, K, V> IterMut<'a, K, V> {
/// Returns an iterator of references over the remaining items.
#[inline]
pub(super) fn iter(&self) -> Iter<'_, K, V> {
Iter { range: self.range.reborrow(), length: self.length }
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V, A: Allocator + Clone> IntoIterator for BTreeMap<K, V, A> {
type Item = (K, V);
type IntoIter = IntoIter<K, V, A>;
fn into_iter(self) -> IntoIter<K, V, A> {
let mut me = ManuallyDrop::new(self);
if let Some(root) = me.root.take() {
let full_range = root.into_dying().full_range();
IntoIter {
range: full_range,
length: me.length,
alloc: unsafe { ManuallyDrop::take(&mut me.alloc) },
}
} else {
IntoIter {
range: LazyLeafRange::none(),
length: 0,
alloc: unsafe { ManuallyDrop::take(&mut me.alloc) },
}
}
}
}
#[stable(feature = "btree_drop", since = "1.7.0")]
impl<K, V, A: Allocator + Clone> Drop for IntoIter<K, V, A> {
fn drop(&mut self) {
struct DropGuard<'a, K, V, A: Allocator + Clone>(&'a mut IntoIter<K, V, A>);
impl<'a, K, V, A: Allocator + Clone> Drop for DropGuard<'a, K, V, A> {
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(kv) = self.0.dying_next() {
// SAFETY: we consume the dying handle immediately.
unsafe { kv.drop_key_val() };
}
}
}
while let Some(kv) = self.dying_next() {
let guard = DropGuard(self);
// SAFETY: we don't touch the tree before consuming the dying handle.
unsafe { kv.drop_key_val() };
mem::forget(guard);
}
}
}
impl<K, V, A: Allocator + Clone> IntoIter<K, V, A> {
/// Core of a `next` method returning a dying KV handle,
/// invalidated by further calls to this function and some others.
fn dying_next(
&mut self,
) -> Option<Handle<NodeRef<marker::Dying, K, V, marker::LeafOrInternal>, marker::KV>> {
if self.length == 0 {
self.range.deallocating_end(self.alloc.clone());
None
} else {
self.length -= 1;
Some(unsafe { self.range.deallocating_next_unchecked(self.alloc.clone()) })
}
}
/// Core of a `next_back` method returning a dying KV handle,
/// invalidated by further calls to this function and some others.
fn dying_next_back(
&mut self,
) -> Option<Handle<NodeRef<marker::Dying, K, V, marker::LeafOrInternal>, marker::KV>> {
if self.length == 0 {
self.range.deallocating_end(self.alloc.clone());
None
} else {
self.length -= 1;
Some(unsafe { self.range.deallocating_next_back_unchecked(self.alloc.clone()) })
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V, A: Allocator + Clone> Iterator for IntoIter<K, V, A> {
type Item = (K, V);
fn next(&mut self) -> Option<(K, V)> {
// SAFETY: we consume the dying handle immediately.
self.dying_next().map(unsafe { |kv| kv.into_key_val() })
}
fn size_hint(&self) -> (usize, Option<usize>) {
(self.length, Some(self.length))
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V, A: Allocator + Clone> DoubleEndedIterator for IntoIter<K, V, A> {
fn next_back(&mut self) -> Option<(K, V)> {
// SAFETY: we consume the dying handle immediately.
self.dying_next_back().map(unsafe { |kv| kv.into_key_val() })
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V, A: Allocator + Clone> ExactSizeIterator for IntoIter<K, V, A> {
fn len(&self) -> usize {
self.length
}
}
#[stable(feature = "fused", since = "1.26.0")]
impl<K, V, A: Allocator + Clone> FusedIterator for IntoIter<K, V, A> {}
#[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,
#[unstable(feature = "allocator_api", issue = "32838")] A: Allocator + Clone = Global,
> where
F: 'a + FnMut(&K, &mut V) -> bool,
{
pred: F,
inner: DrainFilterInner<'a, K, V>,
/// The BTreeMap will outlive this IntoIter so we don't care about drop order for `alloc`.
alloc: A,
}
/// Most of the implementation of DrainFilter are generic over the type
/// of the predicate, thus also serving for BTreeSet::DrainFilter.
pub(super) struct DrainFilterInner<'a, K, V> {
/// Reference to the length field in the borrowed map, updated live.
length: &'a mut usize,
/// Buried reference to the root field in the borrowed map.
/// Wrapped in `Option` to allow drop handler to `take` it.
dormant_root: Option<DormantMutRef<'a, Root<K, V>>>,
/// Contains a leaf edge preceding the next element to be returned, or the last leaf edge.
/// Empty if the map has no root, if iteration went beyond the last leaf edge,
/// or if a panic occurred in the predicate.
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, A: Allocator + Clone> Drop for DrainFilter<'_, K, V, F, A>
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, A: Allocator + Clone> Iterator for DrainFilter<'_, K, V, F, A>
where
F: FnMut(&K, &mut V) -> bool,
{
type Item = (K, V);
fn next(&mut self) -> Option<(K, V)> {
self.inner.next(&mut self.pred, self.alloc.clone())
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.inner.size_hint()
}
}
impl<'a, K, V> 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, A: Allocator + Clone>(&mut self, pred: &mut F, alloc: A) -> 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(alloc.clone());
self.dormant_root = Some(DormantMutRef::new(root).1);
},
alloc.clone(),
);
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>) {
// In most of the btree iterators, `self.length` is the number of elements
// yet to be visited. Here, it includes elements that were visited and that
// the predicate decided not to drain. Making this upper bound more tight
// during iteration would require an extra field.
(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)> {
self.inner.next_checked()
}
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> {}
#[stable(feature = "map_into_keys_values", since = "1.54.0")]
impl<K, V, A: Allocator + Clone> Iterator for IntoKeys<K, V, A> {
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()
}
}
#[stable(feature = "map_into_keys_values", since = "1.54.0")]
impl<K, V, A: Allocator + Clone> DoubleEndedIterator for IntoKeys<K, V, A> {
fn next_back(&mut self) -> Option<K> {
self.inner.next_back().map(|(k, _)| k)
}
}
#[stable(feature = "map_into_keys_values", since = "1.54.0")]
impl<K, V, A: Allocator + Clone> ExactSizeIterator for IntoKeys<K, V, A> {
fn len(&self) -> usize {
self.inner.len()
}
}
#[stable(feature = "map_into_keys_values", since = "1.54.0")]
impl<K, V, A: Allocator + Clone> FusedIterator for IntoKeys<K, V, A> {}
#[stable(feature = "map_into_keys_values", since = "1.54.0")]
impl<K, V, A: Allocator + Clone> Iterator for IntoValues<K, V, A> {
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()
}
}
#[stable(feature = "map_into_keys_values", since = "1.54.0")]
impl<K, V, A: Allocator + Clone> DoubleEndedIterator for IntoValues<K, V, A> {
fn next_back(&mut self) -> Option<V> {
self.inner.next_back().map(|(_, v)| v)
}
}
#[stable(feature = "map_into_keys_values", since = "1.54.0")]
impl<K, V, A: Allocator + Clone> ExactSizeIterator for IntoValues<K, V, A> {
fn len(&self) -> usize {
self.inner.len()
}
}
#[stable(feature = "map_into_keys_values", since = "1.54.0")]
impl<K, V, A: Allocator + Clone> FusedIterator for IntoValues<K, V, A> {}
#[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)> {
self.inner.next_back_checked()
}
}
#[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 { inner: self.inner.clone() }
}
}
#[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)> {
self.inner.next_checked()
}
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 = "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)> {
self.inner.next_back_checked()
}
}
#[stable(feature = "fused", since = "1.26.0")]
impl<K, V> FusedIterator for RangeMut<'_, K, V> {}
#[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 inputs: Vec<_> = iter.into_iter().collect();
if inputs.is_empty() {
return BTreeMap::new();
}
// use stable sort to preserve the insertion order.
inputs.sort_by(|a, b| a.0.cmp(&b.0));
BTreeMap::bulk_build_from_sorted_iter(inputs, Global)
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K: Ord, V, A: Allocator + Clone> Extend<(K, V)> for BTreeMap<K, V, A> {
#[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, A: Allocator + Clone> Extend<(&'a K, &'a V)>
for BTreeMap<K, V, A>
{
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, A: Allocator + Clone> Hash for BTreeMap<K, V, A> {
fn hash<H: Hasher>(&self, state: &mut H) {
state.write_length_prefix(self.len());
for elt in self {
elt.hash(state);
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V> Default for BTreeMap<K, V> {
/// Creates an empty `BTreeMap`.
fn default() -> BTreeMap<K, V> {
BTreeMap::new()
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K: PartialEq, V: PartialEq, A: Allocator + Clone> PartialEq for BTreeMap<K, V, A> {
fn eq(&self, other: &BTreeMap<K, V, A>) -> 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, A: Allocator + Clone> Eq for BTreeMap<K, V, A> {}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K: PartialOrd, V: PartialOrd, A: Allocator + Clone> PartialOrd for BTreeMap<K, V, A> {
#[inline]
fn partial_cmp(&self, other: &BTreeMap<K, V, A>) -> Option<Ordering> {
self.iter().partial_cmp(other.iter())
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K: Ord, V: Ord, A: Allocator + Clone> Ord for BTreeMap<K, V, A> {
#[inline]
fn cmp(&self, other: &BTreeMap<K, V, A>) -> Ordering {
self.iter().cmp(other.iter())
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K: Debug, V: Debug, A: Allocator + Clone> Debug for BTreeMap<K, V, A> {
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, Q: ?Sized, V, A: Allocator + Clone> Index<&Q> for BTreeMap<K, V, A>
where
K: Borrow<Q> + Ord,
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")
}
}
#[stable(feature = "std_collections_from_array", since = "1.56.0")]
impl<K: Ord, V, const N: usize> From<[(K, V); N]> for BTreeMap<K, V> {
/// Converts a `[(K, V); N]` into a `BTreeMap<(K, V)>`.
///
/// ```
/// use std::collections::BTreeMap;
///
/// let map1 = BTreeMap::from([(1, 2), (3, 4)]);
/// let map2: BTreeMap<_, _> = [(1, 2), (3, 4)].into();
/// assert_eq!(map1, map2);
/// ```
fn from(mut arr: [(K, V); N]) -> Self {
if N == 0 {
return BTreeMap::new();
}
// use stable sort to preserve the insertion order.
arr.sort_by(|a, b| a.0.cmp(&b.0));
BTreeMap::bulk_build_from_sorted_iter(arr, Global)
}
}
impl<K, V, A: Allocator + Clone> BTreeMap<K, V, A> {
/// 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 full_range = root.reborrow().full_range();
Iter { range: full_range, length: self.length }
} else {
Iter { range: LazyLeafRange::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::from([
/// ("a", 1),
/// ("b", 2),
/// ("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 full_range = root.borrow_valmut().full_range();
IterMut { range: full_range, length: self.length, _marker: PhantomData }
} else {
IterMut { range: LazyLeafRange::none(), length: 0, _marker: PhantomData }
}
}
/// 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);
/// ```
#[must_use]
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(
feature = "const_btree_len",
issue = "71835",
implied_by = "const_btree_new"
)]
pub const 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());
/// ```
#[must_use]
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(
feature = "const_btree_len",
issue = "71835",
implied_by = "const_btree_new"
)]
pub const fn is_empty(&self) -> bool {
self.len() == 0
}
}
#[cfg(test)]
mod tests;