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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 super::borrow::DormantMutRef; use super::node::{self, marker, ForceResult::*, Handle, NodeRef, Root}; use super::search::{self, SearchResult::*}; use super::unwrap_unchecked; mod entry; pub use entry::{Entry, OccupiedEntry, VacantEntry}; use Entry::*; /// Minimum number of elements in nodes that are not a root. /// We might temporarily have fewer elements during methods. pub(super) const MIN_LEN: usize = node::MIN_LEN_AFTER_SPLIT; /// A map based on a B-Tree. /// /// B-Trees represent a fundamental compromise between cache-efficiency and actually minimizing /// the amount of work performed in a search. In theory, a binary search tree (BST) is the optimal /// choice for a sorted map, as a perfectly balanced BST performs the theoretical minimum amount of /// comparisons necessary to find an element (log<sub>2</sub>n). However, in practice the way this /// is done is *very* inefficient for modern computer architectures. In particular, every element /// is stored in its own individually heap-allocated node. This means that every single insertion /// triggers a heap-allocation, and every single comparison should be a cache-miss. Since these /// are both notably expensive things to do in practice, we are forced to at very least reconsider /// the BST strategy. /// /// A B-Tree instead makes each node contain B-1 to 2B-1 elements in a contiguous array. By doing /// this, we reduce the number of allocations by a factor of B, and improve cache efficiency in /// searches. However, this does mean that searches will have to do *more* comparisons on average. /// The precise number of comparisons depends on the node search strategy used. For optimal cache /// efficiency, one could search the nodes linearly. For optimal comparisons, one could search /// the node using binary search. As a compromise, one could also perform a linear search /// that initially only checks every i<sup>th</sup> element for some choice of i. /// /// Currently, our implementation simply performs naive linear search. This provides excellent /// performance on *small* nodes of elements which are cheap to compare. However in the future we /// would like to further explore choosing the optimal search strategy based on the choice of B, /// and possibly other factors. Using linear search, searching for a random element is expected /// to take O(B * log(n)) comparisons, which is generally worse than a BST. In practice, /// however, performance is excellent. /// /// It is a logic error for a key to be modified in such a way that the key's ordering relative to /// any other key, as determined by the [`Ord`] trait, changes while it is in the map. This is /// normally only possible through [`Cell`], [`RefCell`], global state, I/O, or unsafe code. /// /// [`Cell`]: core::cell::Cell /// [`RefCell`]: core::cell::RefCell /// /// # Examples /// /// ``` /// use std::collections::BTreeMap; /// /// // type inference lets us omit an explicit type signature (which /// // would be `BTreeMap<&str, &str>` in this example). /// let mut movie_reviews = BTreeMap::new(); /// /// // review some movies. /// movie_reviews.insert("Office Space", "Deals with real issues in the workplace."); /// movie_reviews.insert("Pulp Fiction", "Masterpiece."); /// movie_reviews.insert("The Godfather", "Very enjoyable."); /// movie_reviews.insert("The Blues Brothers", "Eye lyked it a lot."); /// /// // check for a specific one. /// if !movie_reviews.contains_key("Les Misérables") { /// println!("We've got {} reviews, but Les Misérables ain't one.", /// movie_reviews.len()); /// } /// /// // oops, this review has a lot of spelling mistakes, let's delete it. /// movie_reviews.remove("The Blues Brothers"); /// /// // look up the values associated with some keys. /// let to_find = ["Up!", "Office Space"]; /// for movie in &to_find { /// match movie_reviews.get(movie) { /// Some(review) => println!("{}: {}", movie, review), /// None => println!("{} is unreviewed.", movie) /// } /// } /// /// // Look up the value for a key (will panic if the key is not found). /// println!("Movie review: {}", movie_reviews["Office Space"]); /// /// // iterate over everything. /// for (movie, review) in &movie_reviews { /// println!("{}: \"{}\"", movie, review); /// } /// ``` /// /// `BTreeMap` also implements an [`Entry API`], which allows for more complex /// methods of getting, setting, updating and removing keys and their values: /// /// [`Entry API`]: BTreeMap::entry /// /// ``` /// use std::collections::BTreeMap; /// /// // type inference lets us omit an explicit type signature (which /// // would be `BTreeMap<&str, u8>` in this example). /// let mut player_stats = BTreeMap::new(); /// /// fn random_stat_buff() -> u8 { /// // could actually return some random value here - let's just return /// // some fixed value for now /// 42 /// } /// /// // insert a key only if it doesn't already exist /// player_stats.entry("health").or_insert(100); /// /// // insert a key using a function that provides a new value only if it /// // doesn't already exist /// player_stats.entry("defence").or_insert_with(random_stat_buff); /// /// // update a key, guarding against the key possibly not being set /// let stat = player_stats.entry("attack").or_insert(100); /// *stat += random_stat_buff(); /// ``` #[stable(feature = "rust1", since = "1.0.0")] pub struct BTreeMap<K, V> { root: Option<Root<K, V>>, length: usize, } #[stable(feature = "btree_drop", since = "1.7.0")] unsafe impl<#[may_dangle] K, #[may_dangle] V> Drop for BTreeMap<K, V> { fn drop(&mut self) { unsafe { drop(ptr::read(self).into_iter()); } } } #[stable(feature = "rust1", since = "1.0.0")] impl<K: Clone, V: Clone> Clone for BTreeMap<K, V> { fn clone(&self) -> BTreeMap<K, V> { fn clone_subtree<'a, K: Clone, V: Clone>( node: NodeRef<marker::Immut<'a>, K, V, marker::LeafOrInternal>, ) -> BTreeMap<K, V> where K: 'a, V: 'a, { match node.force() { Leaf(leaf) => { let mut out_tree = BTreeMap { root: Some(Root::new()), length: 0 }; { 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()); { let out_root = BTreeMap::ensure_is_owned(&mut out_tree.root); let mut out_node = out_root.push_internal_level(); let mut in_edge = internal.first_edge(); while let Ok(kv) = in_edge.right_kv() { let (k, v) = kv.into_kv(); in_edge = kv.right_edge(); let k = (*k).clone(); let v = (*v).clone(); let subtree = clone_subtree(in_edge.descend()); // We can't destructure subtree directly // because BTreeMap implements Drop let (subroot, sublength) = unsafe { let subtree = ManuallyDrop::new(subtree); let root = ptr::read(&subtree.root); let length = subtree.length; (root, length) }; out_node.push(k, v, subroot.unwrap_or_else(Root::new)); out_tree.length += 1 + sublength; } } out_tree } } } if self.is_empty() { // Ideally we'd call `BTreeMap::new` here, but that has the `K: // Ord` constraint, which this method lacks. BTreeMap { root: None, length: 0 } } else { clone_subtree(self.root.as_ref().unwrap().reborrow()) // unwrap succeeds because not empty } } } impl<K, Q: ?Sized> super::Recover<Q> for BTreeMap<K, ()> where K: Borrow<Q> + Ord, Q: Ord, { type Key = K; fn get(&self, key: &Q) -> Option<&K> { let root_node = self.root.as_ref()?.reborrow(); match search::search_tree(root_node, key) { Found(handle) => Some(handle.into_kv().0), GoDown(_) => None, } } fn take(&mut self, key: &Q) -> Option<K> { let (map, dormant_map) = DormantMutRef::new(self); let root_node = map.root.as_mut()?.borrow_mut(); match search::search_tree(root_node, key) { Found(handle) => { Some(OccupiedEntry { handle, dormant_map, _marker: PhantomData }.remove_kv().0) } GoDown(_) => None, } } fn replace(&mut self, key: K) -> Option<K> { let (map, dormant_map) = DormantMutRef::new(self); let root_node = Self::ensure_is_owned(&mut map.root).borrow_mut(); match search::search_tree::<marker::Mut<'_>, K, (), K>(root_node, &key) { Found(mut kv) => Some(mem::replace(kv.key_mut(), key)), GoDown(handle) => { VacantEntry { key, handle, dormant_map, _marker: PhantomData }.insert(()); None } } } } /// An iterator over the entries of a `BTreeMap`. /// /// This `struct` is created by the [`iter`] method on [`BTreeMap`]. See its /// documentation for more. /// /// [`iter`]: BTreeMap::iter #[stable(feature = "rust1", since = "1.0.0")] pub struct Iter<'a, K: 'a, V: 'a> { range: Range<'a, K, V>, length: usize, } #[stable(feature = "collection_debug", since = "1.17.0")] impl<K: fmt::Debug, V: fmt::Debug> fmt::Debug for Iter<'_, K, V> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { f.debug_list().entries(self.clone()).finish() } } /// A mutable iterator over the entries of a `BTreeMap`. /// /// This `struct` is created by the [`iter_mut`] method on [`BTreeMap`]. See its /// documentation for more. /// /// [`iter_mut`]: BTreeMap::iter_mut #[stable(feature = "rust1", since = "1.0.0")] #[derive(Debug)] pub struct IterMut<'a, K: 'a, V: 'a> { range: RangeMut<'a, K, V>, length: usize, } /// An owning iterator over the entries of a `BTreeMap`. /// /// This `struct` is created by the [`into_iter`] method on [`BTreeMap`] /// (provided by the `IntoIterator` trait). See its documentation for more. /// /// [`into_iter`]: IntoIterator::into_iter #[stable(feature = "rust1", since = "1.0.0")] pub struct IntoIter<K, V> { front: Option<Handle<NodeRef<marker::Owned, K, V, marker::Leaf>, marker::Edge>>, back: Option<Handle<NodeRef<marker::Owned, K, V, marker::Leaf>, marker::Edge>>, length: usize, } impl<K, V> IntoIter<K, V> { /// Returns an iterator of references over the remaining items. #[inline] pub(super) fn iter(&self) -> Iter<'_, K, V> { let range = Range { front: self.front.as_ref().map(|f| f.reborrow()), back: self.back.as_ref().map(|b| b.reborrow()), }; Iter { range: range, length: self.length } } } #[stable(feature = "collection_debug", since = "1.17.0")] impl<K: fmt::Debug, V: fmt::Debug> fmt::Debug for IntoIter<K, V> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { 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 #[stable(feature = "rust1", since = "1.0.0")] pub struct Keys<'a, K: 'a, V: 'a> { inner: Iter<'a, K, V>, } #[stable(feature = "collection_debug", since = "1.17.0")] impl<K: fmt::Debug, V> fmt::Debug for Keys<'_, K, V> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { f.debug_list().entries(self.clone()).finish() } } /// An iterator over the values of a `BTreeMap`. /// /// This `struct` is created by the [`values`] method on [`BTreeMap`]. See its /// documentation for more. /// /// [`values`]: BTreeMap::values #[stable(feature = "rust1", since = "1.0.0")] pub struct Values<'a, K: 'a, V: 'a> { inner: Iter<'a, K, V>, } #[stable(feature = "collection_debug", since = "1.17.0")] impl<K, V: fmt::Debug> fmt::Debug for Values<'_, K, V> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { f.debug_list().entries(self.clone()).finish() } } /// A mutable iterator over the values of a `BTreeMap`. /// /// This `struct` is created by the [`values_mut`] method on [`BTreeMap`]. See its /// documentation for more. /// /// [`values_mut`]: BTreeMap::values_mut #[stable(feature = "map_values_mut", since = "1.10.0")] pub struct ValuesMut<'a, K: 'a, V: 'a> { 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 #[unstable(feature = "map_into_keys_values", issue = "75294")] pub struct IntoKeys<K, V> { inner: IntoIter<K, V>, } #[unstable(feature = "map_into_keys_values", issue = "75294")] impl<K: fmt::Debug, V> fmt::Debug for IntoKeys<K, V> { 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 #[unstable(feature = "map_into_keys_values", issue = "75294")] pub struct IntoValues<K, V> { inner: IntoIter<K, V>, } #[unstable(feature = "map_into_keys_values", issue = "75294")] impl<K, V: fmt::Debug> fmt::Debug for IntoValues<K, V> { 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 #[stable(feature = "btree_range", since = "1.17.0")] pub struct Range<'a, K: 'a, V: 'a> { front: Option<Handle<NodeRef<marker::Immut<'a>, K, V, marker::Leaf>, marker::Edge>>, back: Option<Handle<NodeRef<marker::Immut<'a>, K, V, marker::Leaf>, marker::Edge>>, } #[stable(feature = "collection_debug", since = "1.17.0")] impl<K: fmt::Debug, V: fmt::Debug> fmt::Debug for Range<'_, K, V> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { f.debug_list().entries(self.clone()).finish() } } /// A mutable iterator over a sub-range of entries in a `BTreeMap`. /// /// This `struct` is created by the [`range_mut`] method on [`BTreeMap`]. See its /// documentation for more. /// /// [`range_mut`]: BTreeMap::range_mut #[stable(feature = "btree_range", since = "1.17.0")] pub struct RangeMut<'a, K: 'a, V: 'a> { front: Option<Handle<NodeRef<marker::ValMut<'a>, K, V, marker::Leaf>, marker::Edge>>, back: Option<Handle<NodeRef<marker::ValMut<'a>, K, V, marker::Leaf>, marker::Edge>>, // Be invariant in `K` and `V` _marker: PhantomData<&'a mut (K, V)>, } #[stable(feature = "collection_debug", since = "1.17.0")] impl<K: fmt::Debug, V: fmt::Debug> fmt::Debug for RangeMut<'_, K, V> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { let range = Range { front: self.front.as_ref().map(|f| f.reborrow()), back: self.back.as_ref().map(|b| b.reborrow()), }; f.debug_list().entries(range).finish() } } impl<K: Ord, V> BTreeMap<K, V> { /// Makes a new, empty `BTreeMap`. /// /// Does not allocate anything on its own. /// /// # Examples /// /// Basic usage: /// /// ``` /// use std::collections::BTreeMap; /// /// let mut map = BTreeMap::new(); /// /// // entries can now be inserted into the empty map /// map.insert(1, "a"); /// ``` #[stable(feature = "rust1", since = "1.0.0")] #[rustc_const_unstable(feature = "const_btree_new", issue = "71835")] pub const fn new() -> BTreeMap<K, V> { BTreeMap { root: None, length: 0 } } /// Clears the map, removing all elements. /// /// # Examples /// /// Basic usage: /// /// ``` /// use std::collections::BTreeMap; /// /// let mut a = BTreeMap::new(); /// a.insert(1, "a"); /// a.clear(); /// assert!(a.is_empty()); /// ``` #[stable(feature = "rust1", since = "1.0.0")] pub fn clear(&mut self) { *self = BTreeMap::new(); } /// Returns a reference to the value corresponding to the key. /// /// The key may be any borrowed form of the map's key type, but the ordering /// on the borrowed form *must* match the ordering on the key type. /// /// # Examples /// /// Basic usage: /// /// ``` /// use std::collections::BTreeMap; /// /// let mut map = BTreeMap::new(); /// map.insert(1, "a"); /// assert_eq!(map.get(&1), Some(&"a")); /// assert_eq!(map.get(&2), None); /// ``` #[stable(feature = "rust1", since = "1.0.0")] pub fn get<Q: ?Sized>(&self, key: &Q) -> Option<&V> where K: Borrow<Q>, Q: Ord, { let root_node = self.root.as_ref()?.reborrow(); match search::search_tree(root_node, key) { Found(handle) => Some(handle.into_kv().1), GoDown(_) => None, } } /// Returns the key-value pair corresponding to the supplied key. /// /// The supplied key may be any borrowed form of the map's key type, but the ordering /// on the borrowed form *must* match the ordering on the key type. /// /// # Examples /// /// ``` /// use std::collections::BTreeMap; /// /// let mut map = BTreeMap::new(); /// map.insert(1, "a"); /// assert_eq!(map.get_key_value(&1), Some((&1, &"a"))); /// assert_eq!(map.get_key_value(&2), None); /// ``` #[stable(feature = "map_get_key_value", since = "1.40.0")] pub fn get_key_value<Q: ?Sized>(&self, k: &Q) -> Option<(&K, &V)> where K: Borrow<Q>, Q: Ord, { let root_node = self.root.as_ref()?.reborrow(); match search::search_tree(root_node, k) { Found(handle) => Some(handle.into_kv()), GoDown(_) => None, } } /// Returns the first key-value pair in the map. /// The key in this pair is the minimum key in the map. /// /// # Examples /// /// Basic usage: /// /// ``` /// #![feature(map_first_last)] /// use std::collections::BTreeMap; /// /// let mut map = BTreeMap::new(); /// assert_eq!(map.first_key_value(), None); /// map.insert(1, "b"); /// map.insert(2, "a"); /// assert_eq!(map.first_key_value(), Some((&1, &"b"))); /// ``` #[unstable(feature = "map_first_last", issue = "62924")] pub fn first_key_value(&self) -> Option<(&K, &V)> { let root_node = self.root.as_ref()?.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 /// /// ``` /// #![feature(map_first_last)] /// use std::collections::BTreeMap; /// /// let mut map = BTreeMap::new(); /// map.insert(1, "a"); /// map.insert(2, "b"); /// if let Some(mut entry) = map.first_entry() { /// if *entry.key() > 0 { /// entry.insert("first"); /// } /// } /// assert_eq!(*map.get(&1).unwrap(), "first"); /// assert_eq!(*map.get(&2).unwrap(), "b"); /// ``` #[unstable(feature = "map_first_last", issue = "62924")] pub fn first_entry(&mut self) -> Option<OccupiedEntry<'_, K, V>> { let (map, dormant_map) = DormantMutRef::new(self); let root_node = map.root.as_mut()?.borrow_mut(); let kv = root_node.first_leaf_edge().right_kv().ok()?; Some(OccupiedEntry { handle: kv.forget_node_type(), dormant_map, _marker: PhantomData }) } /// Removes and returns the first element in the map. /// The key of this element is the minimum key that was in the map. /// /// # Examples /// /// Draining elements in ascending order, while keeping a usable map each iteration. /// /// ``` /// #![feature(map_first_last)] /// use std::collections::BTreeMap; /// /// let mut map = BTreeMap::new(); /// map.insert(1, "a"); /// map.insert(2, "b"); /// while let Some((key, _val)) = map.pop_first() { /// assert!(map.iter().all(|(k, _v)| *k > key)); /// } /// assert!(map.is_empty()); /// ``` #[unstable(feature = "map_first_last", issue = "62924")] pub fn pop_first(&mut self) -> Option<(K, V)> { self.first_entry().map(|entry| entry.remove_entry()) } /// Returns the last key-value pair in the map. /// The key in this pair is the maximum key in the map. /// /// # Examples /// /// Basic usage: /// /// ``` /// #![feature(map_first_last)] /// use std::collections::BTreeMap; /// /// let mut map = BTreeMap::new(); /// map.insert(1, "b"); /// map.insert(2, "a"); /// assert_eq!(map.last_key_value(), Some((&2, &"a"))); /// ``` #[unstable(feature = "map_first_last", issue = "62924")] pub fn last_key_value(&self) -> Option<(&K, &V)> { let root_node = self.root.as_ref()?.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 /// /// ``` /// #![feature(map_first_last)] /// use std::collections::BTreeMap; /// /// let mut map = BTreeMap::new(); /// map.insert(1, "a"); /// map.insert(2, "b"); /// if let Some(mut entry) = map.last_entry() { /// if *entry.key() > 0 { /// entry.insert("last"); /// } /// } /// assert_eq!(*map.get(&1).unwrap(), "a"); /// assert_eq!(*map.get(&2).unwrap(), "last"); /// ``` #[unstable(feature = "map_first_last", issue = "62924")] pub fn last_entry(&mut self) -> Option<OccupiedEntry<'_, K, V>> { let (map, dormant_map) = DormantMutRef::new(self); let root_node = map.root.as_mut()?.borrow_mut(); let kv = root_node.last_leaf_edge().left_kv().ok()?; Some(OccupiedEntry { handle: kv.forget_node_type(), dormant_map, _marker: PhantomData }) } /// Removes and returns the last element in the map. /// The key of this element is the maximum key that was in the map. /// /// # Examples /// /// Draining elements in descending order, while keeping a usable map each iteration. /// /// ``` /// #![feature(map_first_last)] /// use std::collections::BTreeMap; /// /// let mut map = BTreeMap::new(); /// map.insert(1, "a"); /// map.insert(2, "b"); /// while let Some((key, _val)) = map.pop_last() { /// assert!(map.iter().all(|(k, _v)| *k < key)); /// } /// assert!(map.is_empty()); /// ``` #[unstable(feature = "map_first_last", issue = "62924")] pub fn pop_last(&mut self) -> Option<(K, V)> { self.last_entry().map(|entry| entry.remove_entry()) } /// Returns `true` if the map contains a value for the specified key. /// /// The key may be any borrowed form of the map's key type, but the ordering /// on the borrowed form *must* match the ordering on the key type. /// /// # Examples /// /// Basic usage: /// /// ``` /// use std::collections::BTreeMap; /// /// let mut map = BTreeMap::new(); /// map.insert(1, "a"); /// assert_eq!(map.contains_key(&1), true); /// assert_eq!(map.contains_key(&2), false); /// ``` #[stable(feature = "rust1", since = "1.0.0")] pub fn contains_key<Q: ?Sized>(&self, key: &Q) -> bool where K: Borrow<Q>, Q: Ord, { self.get(key).is_some() } /// Returns a mutable reference to the value corresponding to the key. /// /// The key may be any borrowed form of the map's key type, but the ordering /// on the borrowed form *must* match the ordering on the key type. /// /// # Examples /// /// Basic usage: /// /// ``` /// use std::collections::BTreeMap; /// /// let mut map = BTreeMap::new(); /// map.insert(1, "a"); /// if let Some(x) = map.get_mut(&1) { /// *x = "b"; /// } /// assert_eq!(map[&1], "b"); /// ``` // See `get` for implementation notes, this is basically a copy-paste with mut's added #[stable(feature = "rust1", since = "1.0.0")] pub fn get_mut<Q: ?Sized>(&mut self, key: &Q) -> Option<&mut V> where K: Borrow<Q>, Q: Ord, { let root_node = self.root.as_mut()?.borrow_mut(); match search::search_tree(root_node, key) { Found(handle) => Some(handle.into_val_mut()), GoDown(_) => None, } } /// Inserts a key-value pair into the map. /// /// If the map did not have this key present, `None` is returned. /// /// If the map did have this key present, the value is updated, and the old /// value is returned. The key is not updated, though; this matters for /// types that can be `==` without being identical. See the [module-level /// documentation] for more. /// /// [module-level documentation]: index.html#insert-and-complex-keys /// /// # Examples /// /// Basic usage: /// /// ``` /// use std::collections::BTreeMap; /// /// let mut map = BTreeMap::new(); /// assert_eq!(map.insert(37, "a"), None); /// assert_eq!(map.is_empty(), false); /// /// map.insert(37, "b"); /// assert_eq!(map.insert(37, "c"), Some("b")); /// assert_eq!(map[&37], "c"); /// ``` #[stable(feature = "rust1", since = "1.0.0")] pub fn insert(&mut self, key: K, value: V) -> Option<V> { match self.entry(key) { Occupied(mut entry) => Some(entry.insert(value)), Vacant(entry) => { entry.insert(value); None } } } /// Removes a key from the map, returning the value at the key if the key /// was previously in the map. /// /// The key may be any borrowed form of the map's key type, but the ordering /// on the borrowed form *must* match the ordering on the key type. /// /// # Examples /// /// Basic usage: /// /// ``` /// use std::collections::BTreeMap; /// /// let mut map = BTreeMap::new(); /// map.insert(1, "a"); /// assert_eq!(map.remove(&1), Some("a")); /// assert_eq!(map.remove(&1), None); /// ``` #[stable(feature = "rust1", since = "1.0.0")] pub fn remove<Q: ?Sized>(&mut self, key: &Q) -> Option<V> where K: Borrow<Q>, Q: Ord, { self.remove_entry(key).map(|(_, v)| v) } /// Removes a key from the map, returning the stored key and value if the key /// was previously in the map. /// /// The key may be any borrowed form of the map's key type, but the ordering /// on the borrowed form *must* match the ordering on the key type. /// /// # Examples /// /// Basic usage: /// /// ``` /// use std::collections::BTreeMap; /// /// let mut map = BTreeMap::new(); /// map.insert(1, "a"); /// assert_eq!(map.remove_entry(&1), Some((1, "a"))); /// assert_eq!(map.remove_entry(&1), None); /// ``` #[stable(feature = "btreemap_remove_entry", since = "1.45.0")] pub fn remove_entry<Q: ?Sized>(&mut self, key: &Q) -> Option<(K, V)> where K: Borrow<Q>, Q: Ord, { let (map, dormant_map) = DormantMutRef::new(self); let root_node = map.root.as_mut()?.borrow_mut(); match search::search_tree(root_node, key) { Found(handle) => { Some(OccupiedEntry { handle, dormant_map, _marker: PhantomData }.remove_entry()) } GoDown(_) => None, } } /// Retains only the elements specified by the predicate. /// /// In other words, remove all pairs `(k, v)` such that `f(&k, &mut v)` returns `false`. /// /// # Examples /// /// ``` /// #![feature(btree_retain)] /// 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] #[unstable(feature = "btree_retain", issue = "79025")] pub fn retain<F>(&mut self, mut f: F) where F: FnMut(&K, &mut V) -> bool, { self.drain_filter(|k, v| !f(k, v)); } /// Moves all elements from `other` into `Self`, leaving `other` empty. /// /// # Examples /// /// ``` /// use std::collections::BTreeMap; /// /// let mut a = BTreeMap::new(); /// a.insert(1, "a"); /// a.insert(2, "b"); /// a.insert(3, "c"); /// /// let mut b = BTreeMap::new(); /// b.insert(3, "d"); /// b.insert(4, "e"); /// b.insert(5, "f"); /// /// a.append(&mut b); /// /// assert_eq!(a.len(), 5); /// assert_eq!(b.len(), 0); /// /// assert_eq!(a[&1], "a"); /// assert_eq!(a[&2], "b"); /// assert_eq!(a[&3], "d"); /// assert_eq!(a[&4], "e"); /// assert_eq!(a[&5], "f"); /// ``` #[stable(feature = "btree_append", since = "1.11.0")] pub fn append(&mut self, other: &mut Self) { // Do we have to append anything at all? if other.is_empty() { return; } // We can just swap `self` and `other` if `self` is empty. if self.is_empty() { mem::swap(self, other); return; } let self_iter = mem::take(self).into_iter(); let other_iter = mem::take(other).into_iter(); let root = BTreeMap::ensure_is_owned(&mut self.root); root.append_from_sorted_iters(self_iter, other_iter, &mut self.length) } /// Constructs a double-ended iterator over a sub-range of elements in the map. /// The simplest way is to use the range syntax `min..max`, thus `range(min..max)` will /// yield elements from min (inclusive) to max (exclusive). /// The range may also be entered as `(Bound<T>, Bound<T>)`, so for example /// `range((Excluded(4), Included(10)))` will yield a left-exclusive, right-inclusive /// range from 4 to 10. /// /// # Panics /// /// Panics if range `start > end`. /// Panics if range `start == end` and both bounds are `Excluded`. /// /// # Examples /// /// Basic usage: /// /// ``` /// use std::collections::BTreeMap; /// use std::ops::Bound::Included; /// /// let mut map = BTreeMap::new(); /// map.insert(3, "a"); /// map.insert(5, "b"); /// map.insert(8, "c"); /// for (&key, &value) in map.range((Included(&4), Included(&8))) { /// println!("{}: {}", key, value); /// } /// assert_eq!(Some((&5, &"b")), map.range(4..).next()); /// ``` #[stable(feature = "btree_range", since = "1.17.0")] pub fn range<T: ?Sized, R>(&self, range: R) -> Range<'_, K, V> where T: Ord, K: Borrow<T>, R: RangeBounds<T>, { if let Some(root) = &self.root { let (f, b) = root.reborrow().range_search(range); Range { front: Some(f), back: Some(b) } } else { Range { front: None, back: None } } } /// Constructs a mutable double-ended iterator over a sub-range of elements in the map. /// The simplest way is to use the range syntax `min..max`, thus `range(min..max)` will /// yield elements from min (inclusive) to max (exclusive). /// The range may also be entered as `(Bound<T>, Bound<T>)`, so for example /// `range((Excluded(4), Included(10)))` will yield a left-exclusive, right-inclusive /// range from 4 to 10. /// /// # Panics /// /// Panics if range `start > end`. /// Panics if range `start == end` and both bounds are `Excluded`. /// /// # Examples /// /// Basic usage: /// /// ``` /// use std::collections::BTreeMap; /// /// let mut map: BTreeMap<&str, i32> = ["Alice", "Bob", "Carol", "Cheryl"] /// .iter() /// .map(|&s| (s, 0)) /// .collect(); /// for (_, balance) in map.range_mut("B".."Cheryl") { /// *balance += 100; /// } /// for (name, balance) in &map { /// println!("{} => {}", name, balance); /// } /// ``` #[stable(feature = "btree_range", since = "1.17.0")] pub fn range_mut<T: ?Sized, R>(&mut self, range: R) -> RangeMut<'_, K, V> where T: Ord, K: Borrow<T>, R: RangeBounds<T>, { if let Some(root) = &mut self.root { let (f, b) = root.borrow_valmut().range_search(range); RangeMut { front: Some(f), back: Some(b), _marker: PhantomData } } else { RangeMut { front: None, back: None, _marker: PhantomData } } } /// Gets the given key's corresponding entry in the map for in-place manipulation. /// /// # Examples /// /// Basic usage: /// /// ``` /// use std::collections::BTreeMap; /// /// let mut count: BTreeMap<&str, usize> = BTreeMap::new(); /// /// // count the number of occurrences of letters in the vec /// for x in vec!["a", "b", "a", "c", "a", "b"] { /// *count.entry(x).or_insert(0) += 1; /// } /// /// assert_eq!(count["a"], 3); /// ``` #[stable(feature = "rust1", since = "1.0.0")] pub fn entry(&mut self, key: K) -> Entry<'_, K, V> { // FIXME(@porglezomp) Avoid allocating if we don't insert let (map, dormant_map) = DormantMutRef::new(self); let root_node = Self::ensure_is_owned(&mut map.root).borrow_mut(); match search::search_tree(root_node, &key) { Found(handle) => Occupied(OccupiedEntry { handle, dormant_map, _marker: PhantomData }), GoDown(handle) => { Vacant(VacantEntry { key, handle, dormant_map, _marker: PhantomData }) } } } /// Splits the collection into two at the given key. Returns everything after the given key, /// including the key. /// /// # Examples /// /// Basic usage: /// /// ``` /// use std::collections::BTreeMap; /// /// let mut a = BTreeMap::new(); /// a.insert(1, "a"); /// a.insert(2, "b"); /// a.insert(3, "c"); /// a.insert(17, "d"); /// a.insert(41, "e"); /// /// let b = a.split_off(&3); /// /// assert_eq!(a.len(), 2); /// assert_eq!(b.len(), 3); /// /// assert_eq!(a[&1], "a"); /// assert_eq!(a[&2], "b"); /// /// assert_eq!(b[&3], "c"); /// assert_eq!(b[&17], "d"); /// assert_eq!(b[&41], "e"); /// ``` #[stable(feature = "btree_split_off", since = "1.11.0")] pub fn split_off<Q: ?Sized + Ord>(&mut self, key: &Q) -> Self where K: Borrow<Q>, { if self.is_empty() { return Self::new(); } let total_num = self.len(); let left_root = self.root.as_mut().unwrap(); // unwrap succeeds because not empty let mut right = Self::new(); let right_root = Self::ensure_is_owned(&mut right.root); left_root.split_off(right_root, key); if left_root.height() < right_root.height() { self.length = left_root.reborrow().calc_length(); right.length = total_num - self.len(); } else { right.length = right_root.reborrow().calc_length(); self.length = total_num - right.len(); } right } /// Creates an iterator which uses a closure to determine if an element should be removed. /// /// If the closure returns true, the element is removed from the map and yielded. /// If the closure returns false, or panics, the element remains in the map and will not be /// yielded. /// /// Note that `drain_filter` lets you mutate every value in the filter closure, regardless of /// whether you choose to keep or remove it. /// /// If the iterator is only partially consumed or not consumed at all, each of the remaining /// elements will still be subjected to the closure and removed and dropped if it returns true. /// /// It is unspecified how many more elements will be subjected to the closure /// if a panic occurs in the closure, or a panic occurs while dropping an element, /// or if the `DrainFilter` value is leaked. /// /// # Examples /// /// Splitting a map into even and odd keys, reusing the original map: /// /// ``` /// #![feature(btree_drain_filter)] /// use std::collections::BTreeMap; /// /// let mut map: BTreeMap<i32, i32> = (0..8).map(|x| (x, x)).collect(); /// let evens: BTreeMap<_, _> = map.drain_filter(|k, _v| k % 2 == 0).collect(); /// let odds = map; /// assert_eq!(evens.keys().copied().collect::<Vec<_>>(), vec![0, 2, 4, 6]); /// assert_eq!(odds.keys().copied().collect::<Vec<_>>(), vec![1, 3, 5, 7]); /// ``` #[unstable(feature = "btree_drain_filter", issue = "70530")] pub fn drain_filter<F>(&mut self, pred: F) -> DrainFilter<'_, K, V, F> where F: FnMut(&K, &mut V) -> bool, { DrainFilter { pred, inner: self.drain_filter_inner() } } pub(super) fn drain_filter_inner(&mut self) -> DrainFilterInner<'_, K, V> { if let Some(root) = self.root.as_mut() { let (root, dormant_root) = DormantMutRef::new(root); let front = root.borrow_mut().first_leaf_edge(); DrainFilterInner { length: &mut self.length, dormant_root: Some(dormant_root), cur_leaf_edge: Some(front), } } else { DrainFilterInner { length: &mut self.length, dormant_root: None, cur_leaf_edge: None } } } /// Creates a consuming iterator visiting all the keys, in sorted order. /// The map cannot be used after calling this. /// The iterator element type is `K`. /// /// # Examples /// /// ``` /// #![feature(map_into_keys_values)] /// use std::collections::BTreeMap; /// /// let mut a = BTreeMap::new(); /// a.insert(2, "b"); /// a.insert(1, "a"); /// /// let keys: Vec<i32> = a.into_keys().collect(); /// assert_eq!(keys, [1, 2]); /// ``` #[inline] #[unstable(feature = "map_into_keys_values", issue = "75294")] pub fn into_keys(self) -> IntoKeys<K, V> { IntoKeys { inner: self.into_iter() } } /// Creates a consuming iterator visiting all the values, in order by key. /// The map cannot be used after calling this. /// The iterator element type is `V`. /// /// # Examples /// /// ``` /// #![feature(map_into_keys_values)] /// use std::collections::BTreeMap; /// /// let mut a = BTreeMap::new(); /// a.insert(1, "hello"); /// a.insert(2, "goodbye"); /// /// let values: Vec<&str> = a.into_values().collect(); /// assert_eq!(values, ["hello", "goodbye"]); /// ``` #[inline] #[unstable(feature = "map_into_keys_values", issue = "75294")] pub fn into_values(self) -> IntoValues<K, V> { IntoValues { inner: self.into_iter() } } } #[stable(feature = "rust1", since = "1.0.0")] impl<'a, K, V> IntoIterator for &'a BTreeMap<K, V> { type Item = (&'a K, &'a V); type IntoIter = Iter<'a, K, V>; fn into_iter(self) -> Iter<'a, K, V> { self.iter() } } #[stable(feature = "rust1", since = "1.0.0")] impl<'a, K: 'a, V: 'a> Iterator for Iter<'a, K, V> { type Item = (&'a K, &'a V); fn next(&mut self) -> Option<(&'a K, &'a V)> { if self.length == 0 { None } else { self.length -= 1; unsafe { Some(self.range.next_unchecked()) } } } fn size_hint(&self) -> (usize, Option<usize>) { (self.length, Some(self.length)) } fn last(mut self) -> Option<(&'a K, &'a V)> { self.next_back() } fn min(mut self) -> Option<(&'a K, &'a V)> { self.next() } fn max(mut self) -> Option<(&'a K, &'a V)> { self.next_back() } } #[stable(feature = "fused", since = "1.26.0")] impl<K, V> FusedIterator for Iter<'_, K, V> {} #[stable(feature = "rust1", since = "1.0.0")] impl<'a, K: 'a, V: 'a> DoubleEndedIterator for Iter<'a, K, V> { fn next_back(&mut self) -> Option<(&'a K, &'a V)> { if self.length == 0 { None } else { self.length -= 1; unsafe { Some(self.range.next_back_unchecked()) } } } } #[stable(feature = "rust1", since = "1.0.0")] impl<K, V> ExactSizeIterator for Iter<'_, K, V> { fn len(&self) -> usize { self.length } } #[stable(feature = "rust1", since = "1.0.0")] impl<K, V> Clone for Iter<'_, K, V> { fn clone(&self) -> Self { Iter { range: self.range.clone(), length: self.length } } } #[stable(feature = "rust1", since = "1.0.0")] impl<'a, K, V> IntoIterator for &'a mut BTreeMap<K, V> { type Item = (&'a K, &'a mut V); type IntoIter = IterMut<'a, K, V>; fn into_iter(self) -> IterMut<'a, K, V> { self.iter_mut() } } #[stable(feature = "rust1", since = "1.0.0")] impl<'a, K: 'a, V: 'a> Iterator for IterMut<'a, K, V> { type Item = (&'a K, &'a mut V); fn next(&mut self) -> Option<(&'a K, &'a mut V)> { if self.length == 0 { None } else { self.length -= 1; let (k, v) = unsafe { self.range.next_unchecked() }; Some((k, v)) // coerce k from `&mut K` to `&K` } } fn size_hint(&self) -> (usize, Option<usize>) { (self.length, Some(self.length)) } fn last(mut self) -> Option<(&'a K, &'a mut V)> { self.next_back() } fn min(mut self) -> Option<(&'a K, &'a mut V)> { self.next() } fn max(mut self) -> Option<(&'a K, &'a mut V)> { self.next_back() } } #[stable(feature = "rust1", since = "1.0.0")] impl<'a, K: 'a, V: 'a> DoubleEndedIterator for IterMut<'a, K, V> { fn next_back(&mut self) -> Option<(&'a K, &'a mut V)> { if self.length == 0 { None } else { self.length -= 1; let (k, v) = unsafe { self.range.next_back_unchecked() }; Some((k, v)) // coerce k from `&mut K` to `&K` } } } #[stable(feature = "rust1", since = "1.0.0")] impl<K, V> ExactSizeIterator for IterMut<'_, K, V> { fn len(&self) -> usize { self.length } } #[stable(feature = "fused", since = "1.26.0")] impl<K, V> FusedIterator for IterMut<'_, K, V> {} 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.iter(), length: self.length } } } #[stable(feature = "rust1", since = "1.0.0")] impl<K, V> IntoIterator for BTreeMap<K, V> { type Item = (K, V); type IntoIter = IntoIter<K, V>; fn into_iter(self) -> IntoIter<K, V> { let mut me = ManuallyDrop::new(self); if let Some(root) = me.root.take() { let (f, b) = root.full_range(); IntoIter { front: Some(f), back: Some(b), length: me.length } } else { IntoIter { front: None, back: None, length: 0 } } } } #[stable(feature = "btree_drop", since = "1.7.0")] impl<K, V> Drop for IntoIter<K, V> { fn drop(&mut self) { struct DropGuard<'a, K, V>(&'a mut IntoIter<K, V>); impl<'a, K, V> Drop for DropGuard<'a, K, V> { fn drop(&mut self) { // Continue the same loop we perform below. This only runs when unwinding, so we // don't have to care about panics this time (they'll abort). while let Some(_) = self.0.next() {} unsafe { let mut node = unwrap_unchecked(ptr::read(&self.0.front)).into_node().forget_type(); while let Some(parent) = node.deallocate_and_ascend() { node = parent.into_node().forget_type(); } } } } while let Some(pair) = self.next() { let guard = DropGuard(self); drop(pair); mem::forget(guard); } unsafe { if let Some(front) = ptr::read(&self.front) { let mut node = front.into_node().forget_type(); // Most of the nodes have been deallocated while traversing // but one pile from a leaf up to the root is left standing. while let Some(parent) = node.deallocate_and_ascend() { node = parent.into_node().forget_type(); } } } } } #[stable(feature = "rust1", since = "1.0.0")] impl<K, V> Iterator for IntoIter<K, V> { type Item = (K, V); fn next(&mut self) -> Option<(K, V)> { if self.length == 0 { None } else { self.length -= 1; Some(unsafe { self.front.as_mut().unwrap().next_unchecked() }) } } fn size_hint(&self) -> (usize, Option<usize>) { (self.length, Some(self.length)) } } #[stable(feature = "rust1", since = "1.0.0")] impl<K, V> DoubleEndedIterator for IntoIter<K, V> { fn next_back(&mut self) -> Option<(K, V)> { if self.length == 0 { None } else { self.length -= 1; Some(unsafe { self.back.as_mut().unwrap().next_back_unchecked() }) } } } #[stable(feature = "rust1", since = "1.0.0")] impl<K, V> ExactSizeIterator for IntoIter<K, V> { fn len(&self) -> usize { self.length } } #[stable(feature = "fused", since = "1.26.0")] impl<K, V> FusedIterator for IntoIter<K, V> {} #[stable(feature = "rust1", since = "1.0.0")] impl<'a, K, V> Iterator for Keys<'a, K, V> { type Item = &'a K; fn next(&mut self) -> Option<&'a K> { self.inner.next().map(|(k, _)| k) } fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() } fn last(mut self) -> Option<&'a K> { self.next_back() } fn min(mut self) -> Option<&'a K> { self.next() } fn max(mut self) -> Option<&'a K> { self.next_back() } } #[stable(feature = "rust1", since = "1.0.0")] impl<'a, K, V> DoubleEndedIterator for Keys<'a, K, V> { fn next_back(&mut self) -> Option<&'a K> { self.inner.next_back().map(|(k, _)| k) } } #[stable(feature = "rust1", since = "1.0.0")] impl<K, V> ExactSizeIterator for Keys<'_, K, V> { fn len(&self) -> usize { self.inner.len() } } #[stable(feature = "fused", since = "1.26.0")] impl<K, V> FusedIterator for Keys<'_, K, V> {} #[stable(feature = "rust1", since = "1.0.0")] impl<K, V> Clone for Keys<'_, K, V> { fn clone(&self) -> Self { Keys { inner: self.inner.clone() } } } #[stable(feature = "rust1", since = "1.0.0")] impl<'a, K, V> Iterator for Values<'a, K, V> { type Item = &'a V; fn next(&mut self) -> Option<&'a V> { self.inner.next().map(|(_, v)| v) } fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() } fn last(mut self) -> Option<&'a V> { self.next_back() } } #[stable(feature = "rust1", since = "1.0.0")] impl<'a, K, V> DoubleEndedIterator for Values<'a, K, V> { fn next_back(&mut self) -> Option<&'a V> { self.inner.next_back().map(|(_, v)| v) } } #[stable(feature = "rust1", since = "1.0.0")] impl<K, V> ExactSizeIterator for Values<'_, K, V> { fn len(&self) -> usize { self.inner.len() } } #[stable(feature = "fused", since = "1.26.0")] impl<K, V> FusedIterator for Values<'_, K, V> {} #[stable(feature = "rust1", since = "1.0.0")] impl<K, V> Clone for Values<'_, K, V> { fn clone(&self) -> Self { Values { inner: self.inner.clone() } } } /// An iterator produced by calling `drain_filter` on BTreeMap. #[unstable(feature = "btree_drain_filter", issue = "70530")] pub struct DrainFilter<'a, K, V, F> where K: 'a, V: 'a, F: 'a + FnMut(&K, &mut V) -> bool, { pred: F, inner: DrainFilterInner<'a, K, V>, } /// Most of the implementation of DrainFilter are generic over the type /// of the predicate, thus also serving for BTreeSet::DrainFilter. pub(super) struct DrainFilterInner<'a, K: 'a, V: 'a> { /// 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> Drop for DrainFilter<'_, K, V, F> where F: FnMut(&K, &mut V) -> bool, { fn drop(&mut self) { self.for_each(drop); } } #[unstable(feature = "btree_drain_filter", issue = "70530")] impl<K, V, F> fmt::Debug for DrainFilter<'_, K, V, F> where K: fmt::Debug, V: fmt::Debug, F: FnMut(&K, &mut V) -> bool, { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { f.debug_tuple("DrainFilter").field(&self.inner.peek()).finish() } } #[unstable(feature = "btree_drain_filter", issue = "70530")] impl<K, V, F> Iterator for DrainFilter<'_, K, V, F> where F: FnMut(&K, &mut V) -> bool, { type Item = (K, V); fn next(&mut self) -> Option<(K, V)> { self.inner.next(&mut self.pred) } fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() } } impl<'a, K: 'a, V: 'a> DrainFilterInner<'a, K, V> { /// Allow Debug implementations to predict the next element. pub(super) fn peek(&self) -> Option<(&K, &V)> { let edge = self.cur_leaf_edge.as_ref()?; edge.reborrow().next_kv().ok().map(Handle::into_kv) } /// Implementation of a typical `DrainFilter::next` method, given the predicate. pub(super) fn next<F>(&mut self, pred: &mut F) -> Option<(K, V)> where F: FnMut(&K, &mut V) -> bool, { while let Ok(mut kv) = self.cur_leaf_edge.take()?.next_kv() { let (k, v) = kv.kv_mut(); if pred(k, v) { *self.length -= 1; let (kv, pos) = kv.remove_kv_tracking(|| { // SAFETY: we will touch the root in a way that will not // invalidate the position returned. let root = unsafe { self.dormant_root.take().unwrap().awaken() }; root.pop_internal_level(); self.dormant_root = Some(DormantMutRef::new(root).1); }); self.cur_leaf_edge = Some(pos); return Some(kv); } self.cur_leaf_edge = Some(kv.next_leaf_edge()); } None } /// Implementation of a typical `DrainFilter::size_hint` method. pub(super) fn size_hint(&self) -> (usize, Option<usize>) { // 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 accurate // requires maintaining an extra field and is not worth while. (0, Some(*self.length)) } } #[unstable(feature = "btree_drain_filter", issue = "70530")] impl<K, V, F> FusedIterator for DrainFilter<'_, K, V, F> where F: FnMut(&K, &mut V) -> bool {} #[stable(feature = "btree_range", since = "1.17.0")] impl<'a, K, V> Iterator for Range<'a, K, V> { type Item = (&'a K, &'a V); fn next(&mut self) -> Option<(&'a K, &'a V)> { if self.is_empty() { None } else { unsafe { Some(self.next_unchecked()) } } } fn last(mut self) -> Option<(&'a K, &'a V)> { self.next_back() } fn min(mut self) -> Option<(&'a K, &'a V)> { self.next() } fn max(mut self) -> Option<(&'a K, &'a V)> { self.next_back() } } #[stable(feature = "map_values_mut", since = "1.10.0")] impl<'a, K, V> Iterator for ValuesMut<'a, K, V> { type Item = &'a mut V; fn next(&mut self) -> Option<&'a mut V> { self.inner.next().map(|(_, v)| v) } fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() } fn last(mut self) -> Option<&'a mut V> { self.next_back() } } #[stable(feature = "map_values_mut", since = "1.10.0")] impl<'a, K, V> DoubleEndedIterator for ValuesMut<'a, K, V> { fn next_back(&mut self) -> Option<&'a mut V> { self.inner.next_back().map(|(_, v)| v) } } #[stable(feature = "map_values_mut", since = "1.10.0")] impl<K, V> ExactSizeIterator for ValuesMut<'_, K, V> { fn len(&self) -> usize { self.inner.len() } } #[stable(feature = "fused", since = "1.26.0")] impl<K, V> FusedIterator for ValuesMut<'_, K, V> {} impl<'a, K, V> Range<'a, K, V> { fn is_empty(&self) -> bool { self.front == self.back } unsafe fn next_unchecked(&mut self) -> (&'a K, &'a V) { unsafe { unwrap_unchecked(self.front.as_mut()).next_unchecked() } } } #[unstable(feature = "map_into_keys_values", issue = "75294")] impl<K, V> Iterator for IntoKeys<K, V> { type Item = K; fn next(&mut self) -> Option<K> { self.inner.next().map(|(k, _)| k) } fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() } fn last(mut self) -> Option<K> { self.next_back() } fn min(mut self) -> Option<K> { self.next() } fn max(mut self) -> Option<K> { self.next_back() } } #[unstable(feature = "map_into_keys_values", issue = "75294")] impl<K, V> DoubleEndedIterator for IntoKeys<K, V> { fn next_back(&mut self) -> Option<K> { self.inner.next_back().map(|(k, _)| k) } } #[unstable(feature = "map_into_keys_values", issue = "75294")] impl<K, V> ExactSizeIterator for IntoKeys<K, V> { fn len(&self) -> usize { self.inner.len() } } #[unstable(feature = "map_into_keys_values", issue = "75294")] impl<K, V> FusedIterator for IntoKeys<K, V> {} #[unstable(feature = "map_into_keys_values", issue = "75294")] impl<K, V> Iterator for IntoValues<K, V> { type Item = V; fn next(&mut self) -> Option<V> { self.inner.next().map(|(_, v)| v) } fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() } fn last(mut self) -> Option<V> { self.next_back() } } #[unstable(feature = "map_into_keys_values", issue = "75294")] impl<K, V> DoubleEndedIterator for IntoValues<K, V> { fn next_back(&mut self) -> Option<V> { self.inner.next_back().map(|(_, v)| v) } } #[unstable(feature = "map_into_keys_values", issue = "75294")] impl<K, V> ExactSizeIterator for IntoValues<K, V> { fn len(&self) -> usize { self.inner.len() } } #[unstable(feature = "map_into_keys_values", issue = "75294")] impl<K, V> FusedIterator for IntoValues<K, V> {} #[stable(feature = "btree_range", since = "1.17.0")] impl<'a, K, V> DoubleEndedIterator for Range<'a, K, V> { fn next_back(&mut self) -> Option<(&'a K, &'a V)> { if self.is_empty() { None } else { Some(unsafe { self.next_back_unchecked() }) } } } impl<'a, K, V> Range<'a, K, V> { unsafe fn next_back_unchecked(&mut self) -> (&'a K, &'a V) { unsafe { unwrap_unchecked(self.back.as_mut()).next_back_unchecked() } } } #[stable(feature = "fused", since = "1.26.0")] impl<K, V> FusedIterator for Range<'_, K, V> {} #[stable(feature = "btree_range", since = "1.17.0")] impl<K, V> Clone for Range<'_, K, V> { fn clone(&self) -> Self { Range { front: self.front, back: self.back } } } #[stable(feature = "btree_range", since = "1.17.0")] impl<'a, K, V> Iterator for RangeMut<'a, K, V> { type Item = (&'a K, &'a mut V); fn next(&mut self) -> Option<(&'a K, &'a mut V)> { if self.is_empty() { None } else { let (k, v) = unsafe { self.next_unchecked() }; Some((k, v)) // coerce k from `&mut K` to `&K` } } fn last(mut self) -> Option<(&'a K, &'a mut V)> { self.next_back() } fn min(mut self) -> Option<(&'a K, &'a mut V)> { self.next() } fn max(mut self) -> Option<(&'a K, &'a mut V)> { self.next_back() } } impl<'a, K, V> RangeMut<'a, K, V> { fn is_empty(&self) -> bool { self.front == self.back } unsafe fn next_unchecked(&mut self) -> (&'a K, &'a mut V) { unsafe { unwrap_unchecked(self.front.as_mut()).next_unchecked() } } /// Returns an iterator of references over the remaining items. #[inline] pub(super) fn iter(&self) -> Range<'_, K, V> { Range { front: self.front.as_ref().map(|f| f.reborrow()), back: self.back.as_ref().map(|b| b.reborrow()), } } } #[stable(feature = "btree_range", since = "1.17.0")] impl<'a, K, V> DoubleEndedIterator for RangeMut<'a, K, V> { fn next_back(&mut self) -> Option<(&'a K, &'a mut V)> { if self.is_empty() { None } else { let (k, v) = unsafe { self.next_back_unchecked() }; Some((k, v)) // coerce k from `&mut K` to `&K` } } } #[stable(feature = "fused", since = "1.26.0")] impl<K, V> FusedIterator for RangeMut<'_, K, V> {} impl<'a, K, V> RangeMut<'a, K, V> { unsafe fn next_back_unchecked(&mut self) -> (&'a K, &'a mut V) { unsafe { unwrap_unchecked(self.back.as_mut()).next_back_unchecked() } } } #[stable(feature = "rust1", since = "1.0.0")] impl<K: Ord, V> FromIterator<(K, V)> for BTreeMap<K, V> { fn from_iter<T: IntoIterator<Item = (K, V)>>(iter: T) -> BTreeMap<K, V> { let mut map = BTreeMap::new(); map.extend(iter); map } } #[stable(feature = "rust1", since = "1.0.0")] impl<K: Ord, V> Extend<(K, V)> for BTreeMap<K, V> { #[inline] fn extend<T: IntoIterator<Item = (K, V)>>(&mut self, iter: T) { iter.into_iter().for_each(move |(k, v)| { self.insert(k, v); }); } #[inline] fn extend_one(&mut self, (k, v): (K, V)) { self.insert(k, v); } } #[stable(feature = "extend_ref", since = "1.2.0")] impl<'a, K: Ord + Copy, V: Copy> Extend<(&'a K, &'a V)> for BTreeMap<K, V> { fn extend<I: IntoIterator<Item = (&'a K, &'a V)>>(&mut self, iter: I) { self.extend(iter.into_iter().map(|(&key, &value)| (key, value))); } #[inline] fn extend_one(&mut self, (&k, &v): (&'a K, &'a V)) { self.insert(k, v); } } #[stable(feature = "rust1", since = "1.0.0")] impl<K: Hash, V: Hash> Hash for BTreeMap<K, V> { fn hash<H: Hasher>(&self, state: &mut H) { for elt in self { elt.hash(state); } } } #[stable(feature = "rust1", since = "1.0.0")] impl<K: Ord, V> Default for BTreeMap<K, V> { /// Creates an empty `BTreeMap`. fn default() -> BTreeMap<K, V> { BTreeMap::new() } } #[stable(feature = "rust1", since = "1.0.0")] impl<K: PartialEq, V: PartialEq> PartialEq for BTreeMap<K, V> { fn eq(&self, other: &BTreeMap<K, V>) -> bool { self.len() == other.len() && self.iter().zip(other).all(|(a, b)| a == b) } } #[stable(feature = "rust1", since = "1.0.0")] impl<K: Eq, V: Eq> Eq for BTreeMap<K, V> {} #[stable(feature = "rust1", since = "1.0.0")] impl<K: PartialOrd, V: PartialOrd> PartialOrd for BTreeMap<K, V> { #[inline] fn partial_cmp(&self, other: &BTreeMap<K, V>) -> Option<Ordering> { self.iter().partial_cmp(other.iter()) } } #[stable(feature = "rust1", since = "1.0.0")] impl<K: Ord, V: Ord> Ord for BTreeMap<K, V> { #[inline] fn cmp(&self, other: &BTreeMap<K, V>) -> Ordering { self.iter().cmp(other.iter()) } } #[stable(feature = "rust1", since = "1.0.0")] impl<K: Debug, V: Debug> Debug for BTreeMap<K, V> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { f.debug_map().entries(self.iter()).finish() } } #[stable(feature = "rust1", since = "1.0.0")] impl<K: Ord, Q: ?Sized, V> Index<&Q> for BTreeMap<K, V> where K: Borrow<Q>, Q: Ord, { type Output = V; /// Returns a reference to the value corresponding to the supplied key. /// /// # Panics /// /// Panics if the key is not present in the `BTreeMap`. #[inline] fn index(&self, key: &Q) -> &V { self.get(key).expect("no entry found for key") } } impl<K, V> BTreeMap<K, V> { /// Gets an iterator over the entries of the map, sorted by key. /// /// # Examples /// /// Basic usage: /// /// ``` /// use std::collections::BTreeMap; /// /// let mut map = BTreeMap::new(); /// map.insert(3, "c"); /// map.insert(2, "b"); /// map.insert(1, "a"); /// /// for (key, value) in map.iter() { /// println!("{}: {}", key, value); /// } /// /// let (first_key, first_value) = map.iter().next().unwrap(); /// assert_eq!((*first_key, *first_value), (1, "a")); /// ``` #[stable(feature = "rust1", since = "1.0.0")] pub fn iter(&self) -> Iter<'_, K, V> { if let Some(root) = &self.root { let (f, b) = root.reborrow().full_range(); Iter { range: Range { front: Some(f), back: Some(b) }, length: self.length } } else { Iter { range: Range { front: None, back: None }, length: 0 } } } /// Gets a mutable iterator over the entries of the map, sorted by key. /// /// # Examples /// /// Basic usage: /// /// ``` /// use std::collections::BTreeMap; /// /// let mut map = BTreeMap::new(); /// map.insert("a", 1); /// map.insert("b", 2); /// map.insert("c", 3); /// /// // add 10 to the value if the key isn't "a" /// for (key, value) in map.iter_mut() { /// if key != &"a" { /// *value += 10; /// } /// } /// ``` #[stable(feature = "rust1", since = "1.0.0")] pub fn iter_mut(&mut self) -> IterMut<'_, K, V> { if let Some(root) = &mut self.root { let (f, b) = root.borrow_valmut().full_range(); IterMut { range: RangeMut { front: Some(f), back: Some(b), _marker: PhantomData }, length: self.length, } } else { IterMut { range: RangeMut { front: None, back: None, _marker: PhantomData }, length: 0 } } } /// Gets an iterator over the keys of the map, in sorted order. /// /// # Examples /// /// Basic usage: /// /// ``` /// use std::collections::BTreeMap; /// /// let mut a = BTreeMap::new(); /// a.insert(2, "b"); /// a.insert(1, "a"); /// /// let keys: Vec<_> = a.keys().cloned().collect(); /// assert_eq!(keys, [1, 2]); /// ``` #[stable(feature = "rust1", since = "1.0.0")] pub fn keys(&self) -> Keys<'_, K, V> { Keys { inner: self.iter() } } /// Gets an iterator over the values of the map, in order by key. /// /// # Examples /// /// Basic usage: /// /// ``` /// use std::collections::BTreeMap; /// /// let mut a = BTreeMap::new(); /// a.insert(1, "hello"); /// a.insert(2, "goodbye"); /// /// let values: Vec<&str> = a.values().cloned().collect(); /// assert_eq!(values, ["hello", "goodbye"]); /// ``` #[stable(feature = "rust1", since = "1.0.0")] pub fn values(&self) -> Values<'_, K, V> { Values { inner: self.iter() } } /// Gets a mutable iterator over the values of the map, in order by key. /// /// # Examples /// /// Basic usage: /// /// ``` /// use std::collections::BTreeMap; /// /// let mut a = BTreeMap::new(); /// a.insert(1, String::from("hello")); /// a.insert(2, String::from("goodbye")); /// /// for value in a.values_mut() { /// value.push_str("!"); /// } /// /// let values: Vec<String> = a.values().cloned().collect(); /// assert_eq!(values, [String::from("hello!"), /// String::from("goodbye!")]); /// ``` #[stable(feature = "map_values_mut", since = "1.10.0")] pub fn values_mut(&mut self) -> ValuesMut<'_, K, V> { ValuesMut { inner: self.iter_mut() } } /// Returns the number of elements in the map. /// /// # Examples /// /// Basic usage: /// /// ``` /// use std::collections::BTreeMap; /// /// let mut a = BTreeMap::new(); /// assert_eq!(a.len(), 0); /// a.insert(1, "a"); /// assert_eq!(a.len(), 1); /// ``` #[stable(feature = "rust1", since = "1.0.0")] #[rustc_const_unstable(feature = "const_btree_new", issue = "71835")] 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()); /// ``` #[stable(feature = "rust1", since = "1.0.0")] #[rustc_const_unstable(feature = "const_btree_new", issue = "71835")] pub const fn is_empty(&self) -> bool { self.len() == 0 } /// If the root node is the empty (non-allocated) root node, allocate our /// own node. Is an associated function to avoid borrowing the entire BTreeMap. fn ensure_is_owned(root: &mut Option<Root<K, V>>) -> &mut Root<K, V> { root.get_or_insert_with(Root::new) } } #[cfg(test)] mod tests;