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 (log2n). 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 ith 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>, length: usize, /// `ManuallyDrop` to control drop order (needs to be dropped after all the nodes). pub(super) alloc: ManuallyDrop, // For dropck; the `Box` avoids making the `Unpin` impl more strict than before _marker: PhantomData>, } #[stable(feature = "btree_drop", since = "1.7.0")] unsafe impl<#[may_dangle] K, #[may_dangle] V, A: Allocator + Clone> Drop for BTreeMap { 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 core::panic::UnwindSafe for BTreeMap where A: core::panic::UnwindSafe, K: core::panic::RefUnwindSafe, V: core::panic::RefUnwindSafe, { } #[stable(feature = "rust1", since = "1.0.0")] impl Clone for BTreeMap { fn clone(&self) -> BTreeMap { fn clone_subtree<'a, K: Clone, V: Clone, A: Allocator + Clone>( node: NodeRef, K, V, marker::LeafOrInternal>, alloc: A, ) -> BTreeMap 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 super::Recover for BTreeMap where K: Borrow + 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 { 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 { 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::(&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, K, V>, length: usize, } #[stable(feature = "collection_debug", since = "1.17.0")] impl 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, 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 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, length: usize, /// The BTreeMap will outlive this IntoIter so we don't care about drop order for `alloc`. alloc: A, } impl IntoIter { /// 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 Debug for IntoIter { 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 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 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 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 { inner: IntoIter, } #[stable(feature = "map_into_keys_values", since = "1.54.0")] impl fmt::Debug for IntoKeys { 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, } #[stable(feature = "map_into_keys_values", since = "1.54.0")] impl fmt::Debug for IntoValues { 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, K, V>, } #[stable(feature = "collection_debug", since = "1.17.0")] impl 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, K, V>, // Be invariant in `K` and `V` _marker: PhantomData<&'a mut (K, V)>, } #[stable(feature = "collection_debug", since = "1.17.0")] impl 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 BTreeMap { /// 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 { BTreeMap { root: None, length: 0, alloc: ManuallyDrop::new(Global), _marker: PhantomData } } } impl BTreeMap { /// 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 { BTreeMap { root: None, length: 0, alloc: ManuallyDrop::new(alloc), _marker: PhantomData } } } impl BTreeMap { /// 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(&self, key: &Q) -> Option<&V> where K: Borrow + 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(&self, k: &Q) -> Option<(&K, &V)> where K: Borrow + 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> 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> 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(&self, key: &Q) -> bool where K: Borrow + 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(&mut self, key: &Q) -> Option<&mut V> where K: Borrow + 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 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(&mut self, key: &Q) -> Option where K: Borrow + 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(&mut self, key: &Q) -> Option<(K, V)> where K: Borrow + 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 = (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(&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, Bound)`, 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(&self, range: R) -> Range<'_, K, V> where T: Ord, K: Borrow + Ord, R: RangeBounds, { 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, Bound)`, 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(&mut self, range: R) -> RangeMut<'_, K, V> where T: Ord, K: Borrow + Ord, R: RangeBounds, { 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(&mut self, key: &Q) -> Self where K: Borrow + 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 = (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::>(), [0, 2, 4, 6]); /// assert_eq!(odds.keys().copied().collect::>(), [1, 3, 5, 7]); /// ``` #[unstable(feature = "btree_drain_filter", issue = "70530")] pub fn drain_filter(&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 = 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 { 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 { IntoValues { inner: self.into_iter() } } /// Makes a `BTreeMap` from a sorted iterator. pub(crate) fn bulk_build_from_sorted_iter(iter: I, alloc: A) -> Self where K: Ord, I: IntoIterator, { 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 { 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) { (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 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 ExactSizeIterator for Iter<'_, K, V> { fn len(&self) -> usize { self.length } } #[stable(feature = "rust1", since = "1.0.0")] impl 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 { 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) { (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 ExactSizeIterator for IterMut<'_, K, V> { fn len(&self) -> usize { self.length } } #[stable(feature = "fused", since = "1.26.0")] impl 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 IntoIterator for BTreeMap { type Item = (K, V); type IntoIter = IntoIter; fn into_iter(self) -> IntoIter { 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 Drop for IntoIter { fn drop(&mut self) { struct DropGuard<'a, K, V, A: Allocator + Clone>(&'a mut IntoIter); 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 IntoIter { /// 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, 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, 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 Iterator for IntoIter { 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) { (self.length, Some(self.length)) } } #[stable(feature = "rust1", since = "1.0.0")] impl DoubleEndedIterator for IntoIter { 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 ExactSizeIterator for IntoIter { fn len(&self) -> usize { self.length } } #[stable(feature = "fused", since = "1.26.0")] impl FusedIterator for IntoIter {} #[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) { 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 ExactSizeIterator for Keys<'_, K, V> { fn len(&self) -> usize { self.inner.len() } } #[stable(feature = "fused", since = "1.26.0")] impl FusedIterator for Keys<'_, K, V> {} #[stable(feature = "rust1", since = "1.0.0")] impl 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) { 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 ExactSizeIterator for Values<'_, K, V> { fn len(&self) -> usize { self.inner.len() } } #[stable(feature = "fused", since = "1.26.0")] impl FusedIterator for Values<'_, K, V> {} #[stable(feature = "rust1", since = "1.0.0")] impl 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>>, /// 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, K, V, marker::Leaf>, marker::Edge>>, } #[unstable(feature = "btree_drain_filter", issue = "70530")] impl 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 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 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) { 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(&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) { // 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 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) { 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 ExactSizeIterator for ValuesMut<'_, K, V> { fn len(&self) -> usize { self.inner.len() } } #[stable(feature = "fused", since = "1.26.0")] impl FusedIterator for ValuesMut<'_, K, V> {} #[stable(feature = "map_into_keys_values", since = "1.54.0")] impl Iterator for IntoKeys { type Item = K; fn next(&mut self) -> Option { self.inner.next().map(|(k, _)| k) } fn size_hint(&self) -> (usize, Option) { self.inner.size_hint() } fn last(mut self) -> Option { self.next_back() } fn min(mut self) -> Option { self.next() } fn max(mut self) -> Option { self.next_back() } } #[stable(feature = "map_into_keys_values", since = "1.54.0")] impl DoubleEndedIterator for IntoKeys { fn next_back(&mut self) -> Option { self.inner.next_back().map(|(k, _)| k) } } #[stable(feature = "map_into_keys_values", since = "1.54.0")] impl ExactSizeIterator for IntoKeys { fn len(&self) -> usize { self.inner.len() } } #[stable(feature = "map_into_keys_values", since = "1.54.0")] impl FusedIterator for IntoKeys {} #[stable(feature = "map_into_keys_values", since = "1.54.0")] impl Iterator for IntoValues { type Item = V; fn next(&mut self) -> Option { self.inner.next().map(|(_, v)| v) } fn size_hint(&self) -> (usize, Option) { self.inner.size_hint() } fn last(mut self) -> Option { self.next_back() } } #[stable(feature = "map_into_keys_values", since = "1.54.0")] impl DoubleEndedIterator for IntoValues { fn next_back(&mut self) -> Option { self.inner.next_back().map(|(_, v)| v) } } #[stable(feature = "map_into_keys_values", since = "1.54.0")] impl ExactSizeIterator for IntoValues { fn len(&self) -> usize { self.inner.len() } } #[stable(feature = "map_into_keys_values", since = "1.54.0")] impl FusedIterator for IntoValues {} #[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 FusedIterator for Range<'_, K, V> {} #[stable(feature = "btree_range", since = "1.17.0")] impl 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 FusedIterator for RangeMut<'_, K, V> {} #[stable(feature = "rust1", since = "1.0.0")] impl FromIterator<(K, V)> for BTreeMap { fn from_iter>(iter: T) -> BTreeMap { 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 Extend<(K, V)> for BTreeMap { #[inline] fn extend>(&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 { fn extend>(&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 Hash for BTreeMap { fn hash(&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 Default for BTreeMap { /// Creates an empty `BTreeMap`. fn default() -> BTreeMap { BTreeMap::new() } } #[stable(feature = "rust1", since = "1.0.0")] impl PartialEq for BTreeMap { fn eq(&self, other: &BTreeMap) -> bool { self.len() == other.len() && self.iter().zip(other).all(|(a, b)| a == b) } } #[stable(feature = "rust1", since = "1.0.0")] impl Eq for BTreeMap {} #[stable(feature = "rust1", since = "1.0.0")] impl PartialOrd for BTreeMap { #[inline] fn partial_cmp(&self, other: &BTreeMap) -> Option { self.iter().partial_cmp(other.iter()) } } #[stable(feature = "rust1", since = "1.0.0")] impl Ord for BTreeMap { #[inline] fn cmp(&self, other: &BTreeMap) -> Ordering { self.iter().cmp(other.iter()) } } #[stable(feature = "rust1", since = "1.0.0")] impl Debug for BTreeMap { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { f.debug_map().entries(self.iter()).finish() } } #[stable(feature = "rust1", since = "1.0.0")] impl Index<&Q> for BTreeMap where K: Borrow + 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 From<[(K, V); N]> for BTreeMap { /// 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 BTreeMap { /// 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 = 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;