1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 use core::cmp::Ordering;
13 use core::hash::{Hash, Hasher};
14 use core::iter::{FromIterator, Peekable, FusedIterator};
15 use core::marker::PhantomData;
17 use core::{fmt, intrinsics, mem, ptr};
20 use Bound::{Excluded, Included, Unbounded};
21 use range::RangeArgument;
23 use super::node::{self, Handle, NodeRef, marker};
26 use super::node::InsertResult::*;
27 use super::node::ForceResult::*;
28 use super::search::SearchResult::*;
29 use self::UnderflowResult::*;
32 /// A map based on a B-Tree.
34 /// B-Trees represent a fundamental compromise between cache-efficiency and actually minimizing
35 /// the amount of work performed in a search. In theory, a binary search tree (BST) is the optimal
36 /// choice for a sorted map, as a perfectly balanced BST performs the theoretical minimum amount of
37 /// comparisons necessary to find an element (log<sub>2</sub>n). However, in practice the way this
38 /// is done is *very* inefficient for modern computer architectures. In particular, every element
39 /// is stored in its own individually heap-allocated node. This means that every single insertion
40 /// triggers a heap-allocation, and every single comparison should be a cache-miss. Since these
41 /// are both notably expensive things to do in practice, we are forced to at very least reconsider
44 /// A B-Tree instead makes each node contain B-1 to 2B-1 elements in a contiguous array. By doing
45 /// this, we reduce the number of allocations by a factor of B, and improve cache efficiency in
46 /// searches. However, this does mean that searches will have to do *more* comparisons on average.
47 /// The precise number of comparisons depends on the node search strategy used. For optimal cache
48 /// efficiency, one could search the nodes linearly. For optimal comparisons, one could search
49 /// the node using binary search. As a compromise, one could also perform a linear search
50 /// that initially only checks every i<sup>th</sup> element for some choice of i.
52 /// Currently, our implementation simply performs naive linear search. This provides excellent
53 /// performance on *small* nodes of elements which are cheap to compare. However in the future we
54 /// would like to further explore choosing the optimal search strategy based on the choice of B,
55 /// and possibly other factors. Using linear search, searching for a random element is expected
56 /// to take O(B log<sub>B</sub>n) comparisons, which is generally worse than a BST. In practice,
57 /// however, performance is excellent.
59 /// It is a logic error for a key to be modified in such a way that the key's ordering relative to
60 /// any other key, as determined by the [`Ord`] trait, changes while it is in the map. This is
61 /// normally only possible through [`Cell`], [`RefCell`], global state, I/O, or unsafe code.
63 /// [`Ord`]: ../../std/cmp/trait.Ord.html
64 /// [`Cell`]: ../../std/cell/struct.Cell.html
65 /// [`RefCell`]: ../../std/cell/struct.RefCell.html
70 /// use std::collections::BTreeMap;
72 /// // type inference lets us omit an explicit type signature (which
73 /// // would be `BTreeMap<&str, &str>` in this example).
74 /// let mut movie_reviews = BTreeMap::new();
76 /// // review some movies.
77 /// movie_reviews.insert("Office Space", "Deals with real issues in the workplace.");
78 /// movie_reviews.insert("Pulp Fiction", "Masterpiece.");
79 /// movie_reviews.insert("The Godfather", "Very enjoyable.");
80 /// movie_reviews.insert("The Blues Brothers", "Eye lyked it alot.");
82 /// // check for a specific one.
83 /// if !movie_reviews.contains_key("Les Misérables") {
84 /// println!("We've got {} reviews, but Les Misérables ain't one.",
85 /// movie_reviews.len());
88 /// // oops, this review has a lot of spelling mistakes, let's delete it.
89 /// movie_reviews.remove("The Blues Brothers");
91 /// // look up the values associated with some keys.
92 /// let to_find = ["Up!", "Office Space"];
93 /// for book in &to_find {
94 /// match movie_reviews.get(book) {
95 /// Some(review) => println!("{}: {}", book, review),
96 /// None => println!("{} is unreviewed.", book)
100 /// // iterate over everything.
101 /// for (movie, review) in &movie_reviews {
102 /// println!("{}: \"{}\"", movie, review);
106 /// `BTreeMap` also implements an [`Entry API`](#method.entry), which allows
107 /// for more complex methods of getting, setting, updating and removing keys and
111 /// use std::collections::BTreeMap;
113 /// // type inference lets us omit an explicit type signature (which
114 /// // would be `BTreeMap<&str, u8>` in this example).
115 /// let mut player_stats = BTreeMap::new();
117 /// fn random_stat_buff() -> u8 {
118 /// // could actually return some random value here - let's just return
119 /// // some fixed value for now
123 /// // insert a key only if it doesn't already exist
124 /// player_stats.entry("health").or_insert(100);
126 /// // insert a key using a function that provides a new value only if it
127 /// // doesn't already exist
128 /// player_stats.entry("defence").or_insert_with(random_stat_buff);
130 /// // update a key, guarding against the key possibly not being set
131 /// let stat = player_stats.entry("attack").or_insert(100);
132 /// *stat += random_stat_buff();
134 #[stable(feature = "rust1", since = "1.0.0")]
135 pub struct BTreeMap<K, V> {
136 root: node::Root<K, V>,
140 #[stable(feature = "btree_drop", since = "1.7.0")]
141 unsafe impl<#[may_dangle] K, #[may_dangle] V> Drop for BTreeMap<K, V> {
144 drop(ptr::read(self).into_iter());
149 #[stable(feature = "rust1", since = "1.0.0")]
150 impl<K: Clone, V: Clone> Clone for BTreeMap<K, V> {
151 fn clone(&self) -> BTreeMap<K, V> {
152 fn clone_subtree<K: Clone, V: Clone>(node: node::NodeRef<marker::Immut,
155 marker::LeafOrInternal>)
160 let mut out_tree = BTreeMap {
161 root: node::Root::new_leaf(),
166 let mut out_node = match out_tree.root.as_mut().force() {
168 Internal(_) => unreachable!(),
171 let mut in_edge = leaf.first_edge();
172 while let Ok(kv) = in_edge.right_kv() {
173 let (k, v) = kv.into_kv();
174 in_edge = kv.right_edge();
176 out_node.push(k.clone(), v.clone());
177 out_tree.length += 1;
183 Internal(internal) => {
184 let mut out_tree = clone_subtree(internal.first_edge().descend());
187 let mut out_node = out_tree.root.push_level();
188 let mut in_edge = internal.first_edge();
189 while let Ok(kv) = in_edge.right_kv() {
190 let (k, v) = kv.into_kv();
191 in_edge = kv.right_edge();
193 let k = (*k).clone();
194 let v = (*v).clone();
195 let subtree = clone_subtree(in_edge.descend());
197 // We can't destructure subtree directly
198 // because BTreeMap implements Drop
199 let (subroot, sublength) = unsafe {
200 let root = ptr::read(&subtree.root);
201 let length = subtree.length;
202 mem::forget(subtree);
206 out_node.push(k, v, subroot);
207 out_tree.length += 1 + sublength;
216 clone_subtree(self.root.as_ref())
220 impl<K, Q: ?Sized> super::Recover<Q> for BTreeMap<K, ()>
221 where K: Borrow<Q> + Ord,
226 fn get(&self, key: &Q) -> Option<&K> {
227 match search::search_tree(self.root.as_ref(), key) {
228 Found(handle) => Some(handle.into_kv().0),
233 fn take(&mut self, key: &Q) -> Option<K> {
234 match search::search_tree(self.root.as_mut(), key) {
238 length: &mut self.length,
239 _marker: PhantomData,
248 fn replace(&mut self, key: K) -> Option<K> {
249 match search::search_tree::<marker::Mut, K, (), K>(self.root.as_mut(), &key) {
250 Found(handle) => Some(mem::replace(handle.into_kv_mut().0, key)),
255 length: &mut self.length,
256 _marker: PhantomData,
265 /// An iterator over the entries of a `BTreeMap`.
267 /// This `struct` is created by the [`iter`] method on [`BTreeMap`]. See its
268 /// documentation for more.
270 /// [`iter`]: struct.BTreeMap.html#method.iter
271 /// [`BTreeMap`]: struct.BTreeMap.html
272 #[stable(feature = "rust1", since = "1.0.0")]
273 pub struct Iter<'a, K: 'a, V: 'a> {
274 range: Range<'a, K, V>,
278 #[stable(feature = "collection_debug", since = "1.17.0")]
279 impl<'a, K: 'a + fmt::Debug, V: 'a + fmt::Debug> fmt::Debug for Iter<'a, K, V> {
280 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
281 f.debug_list().entries(self.clone()).finish()
285 /// A mutable iterator over the entries of a `BTreeMap`.
287 /// This `struct` is created by the [`iter_mut`] method on [`BTreeMap`]. See its
288 /// documentation for more.
290 /// [`iter_mut`]: struct.BTreeMap.html#method.iter_mut
291 /// [`BTreeMap`]: struct.BTreeMap.html
292 #[stable(feature = "rust1", since = "1.0.0")]
294 pub struct IterMut<'a, K: 'a, V: 'a> {
295 range: RangeMut<'a, K, V>,
299 /// An owning iterator over the entries of a `BTreeMap`.
301 /// This `struct` is created by the [`into_iter`] method on [`BTreeMap`][`BTreeMap`]
302 /// (provided by the `IntoIterator` trait). See its documentation for more.
304 /// [`into_iter`]: struct.BTreeMap.html#method.into_iter
305 /// [`BTreeMap`]: struct.BTreeMap.html
306 #[stable(feature = "rust1", since = "1.0.0")]
307 pub struct IntoIter<K, V> {
308 front: Handle<NodeRef<marker::Owned, K, V, marker::Leaf>, marker::Edge>,
309 back: Handle<NodeRef<marker::Owned, K, V, marker::Leaf>, marker::Edge>,
313 #[stable(feature = "collection_debug", since = "1.17.0")]
314 impl<K: fmt::Debug, V: fmt::Debug> fmt::Debug for IntoIter<K, V> {
315 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
317 front: self.front.reborrow(),
318 back: self.back.reborrow(),
320 f.debug_list().entries(range).finish()
324 /// An iterator over the keys of a `BTreeMap`.
326 /// This `struct` is created by the [`keys`] method on [`BTreeMap`]. See its
327 /// documentation for more.
329 /// [`keys`]: struct.BTreeMap.html#method.keys
330 /// [`BTreeMap`]: struct.BTreeMap.html
331 #[stable(feature = "rust1", since = "1.0.0")]
332 pub struct Keys<'a, K: 'a, V: 'a> {
333 inner: Iter<'a, K, V>,
336 #[stable(feature = "collection_debug", since = "1.17.0")]
337 impl<'a, K: 'a + fmt::Debug, V: 'a> fmt::Debug for Keys<'a, K, V> {
338 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
339 f.debug_list().entries(self.clone()).finish()
343 /// An iterator over the values of a `BTreeMap`.
345 /// This `struct` is created by the [`values`] method on [`BTreeMap`]. See its
346 /// documentation for more.
348 /// [`values`]: struct.BTreeMap.html#method.values
349 /// [`BTreeMap`]: struct.BTreeMap.html
350 #[stable(feature = "rust1", since = "1.0.0")]
351 pub struct Values<'a, K: 'a, V: 'a> {
352 inner: Iter<'a, K, V>,
355 #[stable(feature = "collection_debug", since = "1.17.0")]
356 impl<'a, K: 'a, V: 'a + fmt::Debug> fmt::Debug for Values<'a, K, V> {
357 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
358 f.debug_list().entries(self.clone()).finish()
362 /// A mutable iterator over the values of a `BTreeMap`.
364 /// This `struct` is created by the [`values_mut`] method on [`BTreeMap`]. See its
365 /// documentation for more.
367 /// [`values_mut`]: struct.BTreeMap.html#method.values_mut
368 /// [`BTreeMap`]: struct.BTreeMap.html
369 #[stable(feature = "map_values_mut", since = "1.10.0")]
371 pub struct ValuesMut<'a, K: 'a, V: 'a> {
372 inner: IterMut<'a, K, V>,
375 /// An iterator over a sub-range of entries in a `BTreeMap`.
377 /// This `struct` is created by the [`range`] method on [`BTreeMap`]. See its
378 /// documentation for more.
380 /// [`range`]: struct.BTreeMap.html#method.range
381 /// [`BTreeMap`]: struct.BTreeMap.html
382 #[stable(feature = "btree_range", since = "1.17.0")]
383 pub struct Range<'a, K: 'a, V: 'a> {
384 front: Handle<NodeRef<marker::Immut<'a>, K, V, marker::Leaf>, marker::Edge>,
385 back: Handle<NodeRef<marker::Immut<'a>, K, V, marker::Leaf>, marker::Edge>,
388 #[stable(feature = "collection_debug", since = "1.17.0")]
389 impl<'a, K: 'a + fmt::Debug, V: 'a + fmt::Debug> fmt::Debug for Range<'a, K, V> {
390 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
391 f.debug_list().entries(self.clone()).finish()
395 /// A mutable iterator over a sub-range of entries in a `BTreeMap`.
397 /// This `struct` is created by the [`range_mut`] method on [`BTreeMap`]. See its
398 /// documentation for more.
400 /// [`range_mut`]: struct.BTreeMap.html#method.range_mut
401 /// [`BTreeMap`]: struct.BTreeMap.html
402 #[stable(feature = "btree_range", since = "1.17.0")]
403 pub struct RangeMut<'a, K: 'a, V: 'a> {
404 front: Handle<NodeRef<marker::Mut<'a>, K, V, marker::Leaf>, marker::Edge>,
405 back: Handle<NodeRef<marker::Mut<'a>, K, V, marker::Leaf>, marker::Edge>,
407 // Be invariant in `K` and `V`
408 _marker: PhantomData<&'a mut (K, V)>,
411 #[stable(feature = "collection_debug", since = "1.17.0")]
412 impl<'a, K: 'a + fmt::Debug, V: 'a + fmt::Debug> fmt::Debug for RangeMut<'a, K, V> {
413 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
415 front: self.front.reborrow(),
416 back: self.back.reborrow(),
418 f.debug_list().entries(range).finish()
422 /// A view into a single entry in a map, which may either be vacant or occupied.
424 /// This `enum` is constructed from the [`entry`] method on [`BTreeMap`].
426 /// [`BTreeMap`]: struct.BTreeMap.html
427 /// [`entry`]: struct.BTreeMap.html#method.entry
428 #[stable(feature = "rust1", since = "1.0.0")]
429 pub enum Entry<'a, K: 'a, V: 'a> {
431 #[stable(feature = "rust1", since = "1.0.0")]
432 Vacant(#[stable(feature = "rust1", since = "1.0.0")]
433 VacantEntry<'a, K, V>),
435 /// An occupied entry.
436 #[stable(feature = "rust1", since = "1.0.0")]
437 Occupied(#[stable(feature = "rust1", since = "1.0.0")]
438 OccupiedEntry<'a, K, V>),
441 #[stable(feature= "debug_btree_map", since = "1.12.0")]
442 impl<'a, K: 'a + Debug + Ord, V: 'a + Debug> Debug for Entry<'a, K, V> {
443 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
445 Vacant(ref v) => f.debug_tuple("Entry")
448 Occupied(ref o) => f.debug_tuple("Entry")
455 /// A view into a vacant entry in a `BTreeMap`.
456 /// It is part of the [`Entry`] enum.
458 /// [`Entry`]: enum.Entry.html
459 #[stable(feature = "rust1", since = "1.0.0")]
460 pub struct VacantEntry<'a, K: 'a, V: 'a> {
462 handle: Handle<NodeRef<marker::Mut<'a>, K, V, marker::Leaf>, marker::Edge>,
463 length: &'a mut usize,
465 // Be invariant in `K` and `V`
466 _marker: PhantomData<&'a mut (K, V)>,
469 #[stable(feature= "debug_btree_map", since = "1.12.0")]
470 impl<'a, K: 'a + Debug + Ord, V: 'a> Debug for VacantEntry<'a, K, V> {
471 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
472 f.debug_tuple("VacantEntry")
478 /// A view into an occupied entry in a `BTreeMap`.
479 /// It is part of the [`Entry`] enum.
481 /// [`Entry`]: enum.Entry.html
482 #[stable(feature = "rust1", since = "1.0.0")]
483 pub struct OccupiedEntry<'a, K: 'a, V: 'a> {
484 handle: Handle<NodeRef<marker::Mut<'a>, K, V, marker::LeafOrInternal>, marker::KV>,
486 length: &'a mut usize,
488 // Be invariant in `K` and `V`
489 _marker: PhantomData<&'a mut (K, V)>,
492 #[stable(feature= "debug_btree_map", since = "1.12.0")]
493 impl<'a, K: 'a + Debug + Ord, V: 'a + Debug> Debug for OccupiedEntry<'a, K, V> {
494 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
495 f.debug_struct("OccupiedEntry")
496 .field("key", self.key())
497 .field("value", self.get())
502 // An iterator for merging two sorted sequences into one
503 struct MergeIter<K, V, I: Iterator<Item = (K, V)>> {
508 impl<K: Ord, V> BTreeMap<K, V> {
509 /// Makes a new empty BTreeMap with a reasonable choice for B.
516 /// use std::collections::BTreeMap;
518 /// let mut map = BTreeMap::new();
520 /// // entries can now be inserted into the empty map
521 /// map.insert(1, "a");
523 #[stable(feature = "rust1", since = "1.0.0")]
524 pub fn new() -> BTreeMap<K, V> {
526 root: node::Root::new_leaf(),
531 /// Clears the map, removing all values.
538 /// use std::collections::BTreeMap;
540 /// let mut a = BTreeMap::new();
541 /// a.insert(1, "a");
543 /// assert!(a.is_empty());
545 #[stable(feature = "rust1", since = "1.0.0")]
546 pub fn clear(&mut self) {
547 // FIXME(gereeter) .clear() allocates
548 *self = BTreeMap::new();
551 /// Returns a reference to the value corresponding to the key.
553 /// The key may be any borrowed form of the map's key type, but the ordering
554 /// on the borrowed form *must* match the ordering on the key type.
561 /// use std::collections::BTreeMap;
563 /// let mut map = BTreeMap::new();
564 /// map.insert(1, "a");
565 /// assert_eq!(map.get(&1), Some(&"a"));
566 /// assert_eq!(map.get(&2), None);
568 #[stable(feature = "rust1", since = "1.0.0")]
569 pub fn get<Q: ?Sized>(&self, key: &Q) -> Option<&V>
573 match search::search_tree(self.root.as_ref(), key) {
574 Found(handle) => Some(handle.into_kv().1),
579 /// Returns `true` if the map contains a value for the specified key.
581 /// The key may be any borrowed form of the map's key type, but the ordering
582 /// on the borrowed form *must* match the ordering on the key type.
589 /// use std::collections::BTreeMap;
591 /// let mut map = BTreeMap::new();
592 /// map.insert(1, "a");
593 /// assert_eq!(map.contains_key(&1), true);
594 /// assert_eq!(map.contains_key(&2), false);
596 #[stable(feature = "rust1", since = "1.0.0")]
597 pub fn contains_key<Q: ?Sized>(&self, key: &Q) -> bool
601 self.get(key).is_some()
604 /// Returns a mutable reference to the value corresponding to the key.
606 /// The key may be any borrowed form of the map's key type, but the ordering
607 /// on the borrowed form *must* match the ordering on the key type.
614 /// use std::collections::BTreeMap;
616 /// let mut map = BTreeMap::new();
617 /// map.insert(1, "a");
618 /// if let Some(x) = map.get_mut(&1) {
621 /// assert_eq!(map[&1], "b");
623 // See `get` for implementation notes, this is basically a copy-paste with mut's added
624 #[stable(feature = "rust1", since = "1.0.0")]
625 pub fn get_mut<Q: ?Sized>(&mut self, key: &Q) -> Option<&mut V>
629 match search::search_tree(self.root.as_mut(), key) {
630 Found(handle) => Some(handle.into_kv_mut().1),
635 /// Inserts a key-value pair into the map.
637 /// If the map did not have this key present, `None` is returned.
639 /// If the map did have this key present, the value is updated, and the old
640 /// value is returned. The key is not updated, though; this matters for
641 /// types that can be `==` without being identical. See the [module-level
642 /// documentation] for more.
644 /// [module-level documentation]: index.html#insert-and-complex-keys
651 /// use std::collections::BTreeMap;
653 /// let mut map = BTreeMap::new();
654 /// assert_eq!(map.insert(37, "a"), None);
655 /// assert_eq!(map.is_empty(), false);
657 /// map.insert(37, "b");
658 /// assert_eq!(map.insert(37, "c"), Some("b"));
659 /// assert_eq!(map[&37], "c");
661 #[stable(feature = "rust1", since = "1.0.0")]
662 pub fn insert(&mut self, key: K, value: V) -> Option<V> {
663 match self.entry(key) {
664 Occupied(mut entry) => Some(entry.insert(value)),
672 /// Removes a key from the map, returning the value at the key if the key
673 /// was previously in the map.
675 /// The key may be any borrowed form of the map's key type, but the ordering
676 /// on the borrowed form *must* match the ordering on the key type.
683 /// use std::collections::BTreeMap;
685 /// let mut map = BTreeMap::new();
686 /// map.insert(1, "a");
687 /// assert_eq!(map.remove(&1), Some("a"));
688 /// assert_eq!(map.remove(&1), None);
690 #[stable(feature = "rust1", since = "1.0.0")]
691 pub fn remove<Q: ?Sized>(&mut self, key: &Q) -> Option<V>
695 match search::search_tree(self.root.as_mut(), key) {
699 length: &mut self.length,
700 _marker: PhantomData,
708 /// Moves all elements from `other` into `Self`, leaving `other` empty.
713 /// use std::collections::BTreeMap;
715 /// let mut a = BTreeMap::new();
716 /// a.insert(1, "a");
717 /// a.insert(2, "b");
718 /// a.insert(3, "c");
720 /// let mut b = BTreeMap::new();
721 /// b.insert(3, "d");
722 /// b.insert(4, "e");
723 /// b.insert(5, "f");
725 /// a.append(&mut b);
727 /// assert_eq!(a.len(), 5);
728 /// assert_eq!(b.len(), 0);
730 /// assert_eq!(a[&1], "a");
731 /// assert_eq!(a[&2], "b");
732 /// assert_eq!(a[&3], "d");
733 /// assert_eq!(a[&4], "e");
734 /// assert_eq!(a[&5], "f");
736 #[stable(feature = "btree_append", since = "1.11.0")]
737 pub fn append(&mut self, other: &mut Self) {
738 // Do we have to append anything at all?
739 if other.len() == 0 {
743 // We can just swap `self` and `other` if `self` is empty.
745 mem::swap(self, other);
749 // First, we merge `self` and `other` into a sorted sequence in linear time.
750 let self_iter = mem::replace(self, BTreeMap::new()).into_iter();
751 let other_iter = mem::replace(other, BTreeMap::new()).into_iter();
752 let iter = MergeIter {
753 left: self_iter.peekable(),
754 right: other_iter.peekable(),
757 // Second, we build a tree from the sorted sequence in linear time.
758 self.from_sorted_iter(iter);
759 self.fix_right_edge();
762 /// Constructs a double-ended iterator over a sub-range of elements in the map.
763 /// The simplest way is to use the range syntax `min..max`, thus `range(min..max)` will
764 /// yield elements from min (inclusive) to max (exclusive).
765 /// The range may also be entered as `(Bound<T>, Bound<T>)`, so for example
766 /// `range((Excluded(4), Included(10)))` will yield a left-exclusive, right-inclusive
767 /// range from 4 to 10.
771 /// Panics if range `start > end`.
772 /// Panics if range `start == end` and both bounds are `Excluded`.
779 /// use std::collections::BTreeMap;
780 /// use std::collections::Bound::Included;
782 /// let mut map = BTreeMap::new();
783 /// map.insert(3, "a");
784 /// map.insert(5, "b");
785 /// map.insert(8, "c");
786 /// for (&key, &value) in map.range((Included(&4), Included(&8))) {
787 /// println!("{}: {}", key, value);
789 /// assert_eq!(Some((&5, &"b")), map.range(4..).next());
791 #[stable(feature = "btree_range", since = "1.17.0")]
792 pub fn range<T: ?Sized, R>(&self, range: R) -> Range<K, V>
793 where T: Ord, K: Borrow<T>, R: RangeArgument<T>
795 let root1 = self.root.as_ref();
796 let root2 = self.root.as_ref();
797 let (f, b) = range_search(root1, root2, range);
799 Range { front: f, back: b}
802 /// Constructs a mutable double-ended iterator over a sub-range of elements in the map.
803 /// The simplest way is to use the range syntax `min..max`, thus `range(min..max)` will
804 /// yield elements from min (inclusive) to max (exclusive).
805 /// The range may also be entered as `(Bound<T>, Bound<T>)`, so for example
806 /// `range((Excluded(4), Included(10)))` will yield a left-exclusive, right-inclusive
807 /// range from 4 to 10.
811 /// Panics if range `start > end`.
812 /// Panics if range `start == end` and both bounds are `Excluded`.
819 /// use std::collections::BTreeMap;
821 /// let mut map: BTreeMap<&str, i32> = ["Alice", "Bob", "Carol", "Cheryl"].iter()
822 /// .map(|&s| (s, 0))
824 /// for (_, balance) in map.range_mut("B".."Cheryl") {
827 /// for (name, balance) in &map {
828 /// println!("{} => {}", name, balance);
831 #[stable(feature = "btree_range", since = "1.17.0")]
832 pub fn range_mut<T: ?Sized, R>(&mut self, range: R) -> RangeMut<K, V>
833 where T: Ord, K: Borrow<T>, R: RangeArgument<T>
835 let root1 = self.root.as_mut();
836 let root2 = unsafe { ptr::read(&root1) };
837 let (f, b) = range_search(root1, root2, range);
842 _marker: PhantomData,
846 /// Gets the given key's corresponding entry in the map for in-place manipulation.
853 /// use std::collections::BTreeMap;
855 /// let mut count: BTreeMap<&str, usize> = BTreeMap::new();
857 /// // count the number of occurrences of letters in the vec
858 /// for x in vec!["a","b","a","c","a","b"] {
859 /// *count.entry(x).or_insert(0) += 1;
862 /// assert_eq!(count["a"], 3);
864 #[stable(feature = "rust1", since = "1.0.0")]
865 pub fn entry(&mut self, key: K) -> Entry<K, V> {
866 match search::search_tree(self.root.as_mut(), &key) {
868 Occupied(OccupiedEntry {
870 length: &mut self.length,
871 _marker: PhantomData,
878 length: &mut self.length,
879 _marker: PhantomData,
885 fn from_sorted_iter<I: Iterator<Item = (K, V)>>(&mut self, iter: I) {
886 let mut cur_node = last_leaf_edge(self.root.as_mut()).into_node();
887 // Iterate through all key-value pairs, pushing them into nodes at the right level.
888 for (key, value) in iter {
889 // Try to push key-value pair into the current leaf node.
890 if cur_node.len() < node::CAPACITY {
891 cur_node.push(key, value);
893 // No space left, go up and push there.
895 let mut test_node = cur_node.forget_type();
897 match test_node.ascend() {
899 let parent = parent.into_node();
900 if parent.len() < node::CAPACITY {
901 // Found a node with space left, push here.
906 test_node = parent.forget_type();
910 // We are at the top, create a new root node and push there.
911 open_node = node.into_root_mut().push_level();
917 // Push key-value pair and new right subtree.
918 let tree_height = open_node.height() - 1;
919 let mut right_tree = node::Root::new_leaf();
920 for _ in 0..tree_height {
921 right_tree.push_level();
923 open_node.push(key, value, right_tree);
925 // Go down to the right-most leaf again.
926 cur_node = last_leaf_edge(open_node.forget_type()).into_node();
933 fn fix_right_edge(&mut self) {
934 // Handle underfull nodes, start from the top.
935 let mut cur_node = self.root.as_mut();
936 while let Internal(internal) = cur_node.force() {
937 // Check if right-most child is underfull.
938 let mut last_edge = internal.last_edge();
939 let right_child_len = last_edge.reborrow().descend().len();
940 if right_child_len < node::MIN_LEN {
942 let mut last_kv = match last_edge.left_kv() {
944 Err(_) => unreachable!(),
946 last_kv.bulk_steal_left(node::MIN_LEN - right_child_len);
947 last_edge = last_kv.right_edge();
951 cur_node = last_edge.descend();
955 /// Splits the collection into two at the given key. Returns everything after the given key,
956 /// including the key.
963 /// use std::collections::BTreeMap;
965 /// let mut a = BTreeMap::new();
966 /// a.insert(1, "a");
967 /// a.insert(2, "b");
968 /// a.insert(3, "c");
969 /// a.insert(17, "d");
970 /// a.insert(41, "e");
972 /// let b = a.split_off(&3);
974 /// assert_eq!(a.len(), 2);
975 /// assert_eq!(b.len(), 3);
977 /// assert_eq!(a[&1], "a");
978 /// assert_eq!(a[&2], "b");
980 /// assert_eq!(b[&3], "c");
981 /// assert_eq!(b[&17], "d");
982 /// assert_eq!(b[&41], "e");
984 #[stable(feature = "btree_split_off", since = "1.11.0")]
985 pub fn split_off<Q: ?Sized + Ord>(&mut self, key: &Q) -> Self
992 let total_num = self.len();
994 let mut right = Self::new();
995 for _ in 0..(self.root.as_ref().height()) {
996 right.root.push_level();
1000 let mut left_node = self.root.as_mut();
1001 let mut right_node = right.root.as_mut();
1004 let mut split_edge = match search::search_node(left_node, key) {
1005 // key is going to the right tree
1006 Found(handle) => handle.left_edge(),
1007 GoDown(handle) => handle,
1010 split_edge.move_suffix(&mut right_node);
1012 match (split_edge.force(), right_node.force()) {
1013 (Internal(edge), Internal(node)) => {
1014 left_node = edge.descend();
1015 right_node = node.first_edge().descend();
1017 (Leaf(_), Leaf(_)) => {
1027 self.fix_right_border();
1028 right.fix_left_border();
1030 if self.root.as_ref().height() < right.root.as_ref().height() {
1031 self.recalc_length();
1032 right.length = total_num - self.len();
1034 right.recalc_length();
1035 self.length = total_num - right.len();
1041 /// Calculates the number of elements if it is incorrect.
1042 fn recalc_length(&mut self) {
1043 fn dfs<K, V>(node: NodeRef<marker::Immut, K, V, marker::LeafOrInternal>) -> usize {
1044 let mut res = node.len();
1046 if let Internal(node) = node.force() {
1047 let mut edge = node.first_edge();
1049 res += dfs(edge.reborrow().descend());
1050 match edge.right_kv() {
1052 edge = right_kv.right_edge();
1064 self.length = dfs(self.root.as_ref());
1067 /// Removes empty levels on the top.
1068 fn fix_top(&mut self) {
1071 let node = self.root.as_ref();
1072 if node.height() == 0 || node.len() > 0 {
1076 self.root.pop_level();
1080 fn fix_right_border(&mut self) {
1084 let mut cur_node = self.root.as_mut();
1086 while let Internal(node) = cur_node.force() {
1087 let mut last_kv = node.last_kv();
1089 if last_kv.can_merge() {
1090 cur_node = last_kv.merge().descend();
1092 let right_len = last_kv.reborrow().right_edge().descend().len();
1093 // `MINLEN + 1` to avoid readjust if merge happens on the next level.
1094 if right_len < node::MIN_LEN + 1 {
1095 last_kv.bulk_steal_left(node::MIN_LEN + 1 - right_len);
1097 cur_node = last_kv.right_edge().descend();
1105 /// The symmetric clone of `fix_right_border`.
1106 fn fix_left_border(&mut self) {
1110 let mut cur_node = self.root.as_mut();
1112 while let Internal(node) = cur_node.force() {
1113 let mut first_kv = node.first_kv();
1115 if first_kv.can_merge() {
1116 cur_node = first_kv.merge().descend();
1118 let left_len = first_kv.reborrow().left_edge().descend().len();
1119 if left_len < node::MIN_LEN + 1 {
1120 first_kv.bulk_steal_right(node::MIN_LEN + 1 - left_len);
1122 cur_node = first_kv.left_edge().descend();
1131 #[stable(feature = "rust1", since = "1.0.0")]
1132 impl<'a, K: 'a, V: 'a> IntoIterator for &'a BTreeMap<K, V> {
1133 type Item = (&'a K, &'a V);
1134 type IntoIter = Iter<'a, K, V>;
1136 fn into_iter(self) -> Iter<'a, K, V> {
1141 #[stable(feature = "rust1", since = "1.0.0")]
1142 impl<'a, K: 'a, V: 'a> Iterator for Iter<'a, K, V> {
1143 type Item = (&'a K, &'a V);
1145 fn next(&mut self) -> Option<(&'a K, &'a V)> {
1146 if self.length == 0 {
1150 unsafe { Some(self.range.next_unchecked()) }
1154 fn size_hint(&self) -> (usize, Option<usize>) {
1155 (self.length, Some(self.length))
1159 #[stable(feature = "fused", since = "1.26.0")]
1160 impl<'a, K, V> FusedIterator for Iter<'a, K, V> {}
1162 #[stable(feature = "rust1", since = "1.0.0")]
1163 impl<'a, K: 'a, V: 'a> DoubleEndedIterator for Iter<'a, K, V> {
1164 fn next_back(&mut self) -> Option<(&'a K, &'a V)> {
1165 if self.length == 0 {
1169 unsafe { Some(self.range.next_back_unchecked()) }
1174 #[stable(feature = "rust1", since = "1.0.0")]
1175 impl<'a, K: 'a, V: 'a> ExactSizeIterator for Iter<'a, K, V> {
1176 fn len(&self) -> usize {
1181 #[stable(feature = "rust1", since = "1.0.0")]
1182 impl<'a, K, V> Clone for Iter<'a, K, V> {
1183 fn clone(&self) -> Iter<'a, K, V> {
1185 range: self.range.clone(),
1186 length: self.length,
1191 #[stable(feature = "rust1", since = "1.0.0")]
1192 impl<'a, K: 'a, V: 'a> IntoIterator for &'a mut BTreeMap<K, V> {
1193 type Item = (&'a K, &'a mut V);
1194 type IntoIter = IterMut<'a, K, V>;
1196 fn into_iter(self) -> IterMut<'a, K, V> {
1201 #[stable(feature = "rust1", since = "1.0.0")]
1202 impl<'a, K: 'a, V: 'a> Iterator for IterMut<'a, K, V> {
1203 type Item = (&'a K, &'a mut V);
1205 fn next(&mut self) -> Option<(&'a K, &'a mut V)> {
1206 if self.length == 0 {
1210 unsafe { Some(self.range.next_unchecked()) }
1214 fn size_hint(&self) -> (usize, Option<usize>) {
1215 (self.length, Some(self.length))
1219 #[stable(feature = "rust1", since = "1.0.0")]
1220 impl<'a, K: 'a, V: 'a> DoubleEndedIterator for IterMut<'a, K, V> {
1221 fn next_back(&mut self) -> Option<(&'a K, &'a mut V)> {
1222 if self.length == 0 {
1226 unsafe { Some(self.range.next_back_unchecked()) }
1231 #[stable(feature = "rust1", since = "1.0.0")]
1232 impl<'a, K: 'a, V: 'a> ExactSizeIterator for IterMut<'a, K, V> {
1233 fn len(&self) -> usize {
1238 #[stable(feature = "fused", since = "1.26.0")]
1239 impl<'a, K, V> FusedIterator for IterMut<'a, K, V> {}
1241 #[stable(feature = "rust1", since = "1.0.0")]
1242 impl<K, V> IntoIterator for BTreeMap<K, V> {
1244 type IntoIter = IntoIter<K, V>;
1246 fn into_iter(self) -> IntoIter<K, V> {
1247 let root1 = unsafe { ptr::read(&self.root).into_ref() };
1248 let root2 = unsafe { ptr::read(&self.root).into_ref() };
1249 let len = self.length;
1253 front: first_leaf_edge(root1),
1254 back: last_leaf_edge(root2),
1260 #[stable(feature = "btree_drop", since = "1.7.0")]
1261 impl<K, V> Drop for IntoIter<K, V> {
1262 fn drop(&mut self) {
1263 for _ in &mut *self {
1266 let leaf_node = ptr::read(&self.front).into_node();
1267 if let Some(first_parent) = leaf_node.deallocate_and_ascend() {
1268 let mut cur_node = first_parent.into_node();
1269 while let Some(parent) = cur_node.deallocate_and_ascend() {
1270 cur_node = parent.into_node()
1277 #[stable(feature = "rust1", since = "1.0.0")]
1278 impl<K, V> Iterator for IntoIter<K, V> {
1281 fn next(&mut self) -> Option<(K, V)> {
1282 if self.length == 0 {
1288 let handle = unsafe { ptr::read(&self.front) };
1290 let mut cur_handle = match handle.right_kv() {
1292 let k = unsafe { ptr::read(kv.reborrow().into_kv().0) };
1293 let v = unsafe { ptr::read(kv.reborrow().into_kv().1) };
1294 self.front = kv.right_edge();
1295 return Some((k, v));
1297 Err(last_edge) => unsafe {
1298 unwrap_unchecked(last_edge.into_node().deallocate_and_ascend())
1303 match cur_handle.right_kv() {
1305 let k = unsafe { ptr::read(kv.reborrow().into_kv().0) };
1306 let v = unsafe { ptr::read(kv.reborrow().into_kv().1) };
1307 self.front = first_leaf_edge(kv.right_edge().descend());
1308 return Some((k, v));
1310 Err(last_edge) => unsafe {
1311 cur_handle = unwrap_unchecked(last_edge.into_node().deallocate_and_ascend());
1317 fn size_hint(&self) -> (usize, Option<usize>) {
1318 (self.length, Some(self.length))
1322 #[stable(feature = "rust1", since = "1.0.0")]
1323 impl<K, V> DoubleEndedIterator for IntoIter<K, V> {
1324 fn next_back(&mut self) -> Option<(K, V)> {
1325 if self.length == 0 {
1331 let handle = unsafe { ptr::read(&self.back) };
1333 let mut cur_handle = match handle.left_kv() {
1335 let k = unsafe { ptr::read(kv.reborrow().into_kv().0) };
1336 let v = unsafe { ptr::read(kv.reborrow().into_kv().1) };
1337 self.back = kv.left_edge();
1338 return Some((k, v));
1340 Err(last_edge) => unsafe {
1341 unwrap_unchecked(last_edge.into_node().deallocate_and_ascend())
1346 match cur_handle.left_kv() {
1348 let k = unsafe { ptr::read(kv.reborrow().into_kv().0) };
1349 let v = unsafe { ptr::read(kv.reborrow().into_kv().1) };
1350 self.back = last_leaf_edge(kv.left_edge().descend());
1351 return Some((k, v));
1353 Err(last_edge) => unsafe {
1354 cur_handle = unwrap_unchecked(last_edge.into_node().deallocate_and_ascend());
1361 #[stable(feature = "rust1", since = "1.0.0")]
1362 impl<K, V> ExactSizeIterator for IntoIter<K, V> {
1363 fn len(&self) -> usize {
1368 #[stable(feature = "fused", since = "1.26.0")]
1369 impl<K, V> FusedIterator for IntoIter<K, V> {}
1371 #[stable(feature = "rust1", since = "1.0.0")]
1372 impl<'a, K, V> Iterator for Keys<'a, K, V> {
1375 fn next(&mut self) -> Option<&'a K> {
1376 self.inner.next().map(|(k, _)| k)
1379 fn size_hint(&self) -> (usize, Option<usize>) {
1380 self.inner.size_hint()
1384 #[stable(feature = "rust1", since = "1.0.0")]
1385 impl<'a, K, V> DoubleEndedIterator for Keys<'a, K, V> {
1386 fn next_back(&mut self) -> Option<&'a K> {
1387 self.inner.next_back().map(|(k, _)| k)
1391 #[stable(feature = "rust1", since = "1.0.0")]
1392 impl<'a, K, V> ExactSizeIterator for Keys<'a, K, V> {
1393 fn len(&self) -> usize {
1398 #[stable(feature = "fused", since = "1.26.0")]
1399 impl<'a, K, V> FusedIterator for Keys<'a, K, V> {}
1401 #[stable(feature = "rust1", since = "1.0.0")]
1402 impl<'a, K, V> Clone for Keys<'a, K, V> {
1403 fn clone(&self) -> Keys<'a, K, V> {
1404 Keys { inner: self.inner.clone() }
1408 #[stable(feature = "rust1", since = "1.0.0")]
1409 impl<'a, K, V> Iterator for Values<'a, K, V> {
1412 fn next(&mut self) -> Option<&'a V> {
1413 self.inner.next().map(|(_, v)| v)
1416 fn size_hint(&self) -> (usize, Option<usize>) {
1417 self.inner.size_hint()
1421 #[stable(feature = "rust1", since = "1.0.0")]
1422 impl<'a, K, V> DoubleEndedIterator for Values<'a, K, V> {
1423 fn next_back(&mut self) -> Option<&'a V> {
1424 self.inner.next_back().map(|(_, v)| v)
1428 #[stable(feature = "rust1", since = "1.0.0")]
1429 impl<'a, K, V> ExactSizeIterator for Values<'a, K, V> {
1430 fn len(&self) -> usize {
1435 #[stable(feature = "fused", since = "1.26.0")]
1436 impl<'a, K, V> FusedIterator for Values<'a, K, V> {}
1438 #[stable(feature = "rust1", since = "1.0.0")]
1439 impl<'a, K, V> Clone for Values<'a, K, V> {
1440 fn clone(&self) -> Values<'a, K, V> {
1441 Values { inner: self.inner.clone() }
1445 #[stable(feature = "btree_range", since = "1.17.0")]
1446 impl<'a, K, V> Iterator for Range<'a, K, V> {
1447 type Item = (&'a K, &'a V);
1449 fn next(&mut self) -> Option<(&'a K, &'a V)> {
1450 if self.front == self.back {
1453 unsafe { Some(self.next_unchecked()) }
1458 #[stable(feature = "map_values_mut", since = "1.10.0")]
1459 impl<'a, K, V> Iterator for ValuesMut<'a, K, V> {
1460 type Item = &'a mut V;
1462 fn next(&mut self) -> Option<&'a mut V> {
1463 self.inner.next().map(|(_, v)| v)
1466 fn size_hint(&self) -> (usize, Option<usize>) {
1467 self.inner.size_hint()
1471 #[stable(feature = "map_values_mut", since = "1.10.0")]
1472 impl<'a, K, V> DoubleEndedIterator for ValuesMut<'a, K, V> {
1473 fn next_back(&mut self) -> Option<&'a mut V> {
1474 self.inner.next_back().map(|(_, v)| v)
1478 #[stable(feature = "map_values_mut", since = "1.10.0")]
1479 impl<'a, K, V> ExactSizeIterator for ValuesMut<'a, K, V> {
1480 fn len(&self) -> usize {
1485 #[stable(feature = "fused", since = "1.26.0")]
1486 impl<'a, K, V> FusedIterator for ValuesMut<'a, K, V> {}
1489 impl<'a, K, V> Range<'a, K, V> {
1490 unsafe fn next_unchecked(&mut self) -> (&'a K, &'a V) {
1491 let handle = self.front;
1493 let mut cur_handle = match handle.right_kv() {
1495 let ret = kv.into_kv();
1496 self.front = kv.right_edge();
1500 let next_level = last_edge.into_node().ascend().ok();
1501 unwrap_unchecked(next_level)
1506 match cur_handle.right_kv() {
1508 let ret = kv.into_kv();
1509 self.front = first_leaf_edge(kv.right_edge().descend());
1513 let next_level = last_edge.into_node().ascend().ok();
1514 cur_handle = unwrap_unchecked(next_level);
1521 #[stable(feature = "btree_range", since = "1.17.0")]
1522 impl<'a, K, V> DoubleEndedIterator for Range<'a, K, V> {
1523 fn next_back(&mut self) -> Option<(&'a K, &'a V)> {
1524 if self.front == self.back {
1527 unsafe { Some(self.next_back_unchecked()) }
1532 impl<'a, K, V> Range<'a, K, V> {
1533 unsafe fn next_back_unchecked(&mut self) -> (&'a K, &'a V) {
1534 let handle = self.back;
1536 let mut cur_handle = match handle.left_kv() {
1538 let ret = kv.into_kv();
1539 self.back = kv.left_edge();
1543 let next_level = last_edge.into_node().ascend().ok();
1544 unwrap_unchecked(next_level)
1549 match cur_handle.left_kv() {
1551 let ret = kv.into_kv();
1552 self.back = last_leaf_edge(kv.left_edge().descend());
1556 let next_level = last_edge.into_node().ascend().ok();
1557 cur_handle = unwrap_unchecked(next_level);
1564 #[stable(feature = "fused", since = "1.26.0")]
1565 impl<'a, K, V> FusedIterator for Range<'a, K, V> {}
1567 #[stable(feature = "btree_range", since = "1.17.0")]
1568 impl<'a, K, V> Clone for Range<'a, K, V> {
1569 fn clone(&self) -> Range<'a, K, V> {
1577 #[stable(feature = "btree_range", since = "1.17.0")]
1578 impl<'a, K, V> Iterator for RangeMut<'a, K, V> {
1579 type Item = (&'a K, &'a mut V);
1581 fn next(&mut self) -> Option<(&'a K, &'a mut V)> {
1582 if self.front == self.back {
1585 unsafe { Some(self.next_unchecked()) }
1590 impl<'a, K, V> RangeMut<'a, K, V> {
1591 unsafe fn next_unchecked(&mut self) -> (&'a K, &'a mut V) {
1592 let handle = ptr::read(&self.front);
1594 let mut cur_handle = match handle.right_kv() {
1596 let (k, v) = ptr::read(&kv).into_kv_mut();
1597 self.front = kv.right_edge();
1601 let next_level = last_edge.into_node().ascend().ok();
1602 unwrap_unchecked(next_level)
1607 match cur_handle.right_kv() {
1609 let (k, v) = ptr::read(&kv).into_kv_mut();
1610 self.front = first_leaf_edge(kv.right_edge().descend());
1614 let next_level = last_edge.into_node().ascend().ok();
1615 cur_handle = unwrap_unchecked(next_level);
1622 #[stable(feature = "btree_range", since = "1.17.0")]
1623 impl<'a, K, V> DoubleEndedIterator for RangeMut<'a, K, V> {
1624 fn next_back(&mut self) -> Option<(&'a K, &'a mut V)> {
1625 if self.front == self.back {
1628 unsafe { Some(self.next_back_unchecked()) }
1633 #[stable(feature = "fused", since = "1.26.0")]
1634 impl<'a, K, V> FusedIterator for RangeMut<'a, K, V> {}
1636 impl<'a, K, V> RangeMut<'a, K, V> {
1637 unsafe fn next_back_unchecked(&mut self) -> (&'a K, &'a mut V) {
1638 let handle = ptr::read(&self.back);
1640 let mut cur_handle = match handle.left_kv() {
1642 let (k, v) = ptr::read(&kv).into_kv_mut();
1643 self.back = kv.left_edge();
1647 let next_level = last_edge.into_node().ascend().ok();
1648 unwrap_unchecked(next_level)
1653 match cur_handle.left_kv() {
1655 let (k, v) = ptr::read(&kv).into_kv_mut();
1656 self.back = last_leaf_edge(kv.left_edge().descend());
1660 let next_level = last_edge.into_node().ascend().ok();
1661 cur_handle = unwrap_unchecked(next_level);
1668 #[stable(feature = "rust1", since = "1.0.0")]
1669 impl<K: Ord, V> FromIterator<(K, V)> for BTreeMap<K, V> {
1670 fn from_iter<T: IntoIterator<Item = (K, V)>>(iter: T) -> BTreeMap<K, V> {
1671 let mut map = BTreeMap::new();
1677 #[stable(feature = "rust1", since = "1.0.0")]
1678 impl<K: Ord, V> Extend<(K, V)> for BTreeMap<K, V> {
1680 fn extend<T: IntoIterator<Item = (K, V)>>(&mut self, iter: T) {
1681 for (k, v) in iter {
1687 #[stable(feature = "extend_ref", since = "1.2.0")]
1688 impl<'a, K: Ord + Copy, V: Copy> Extend<(&'a K, &'a V)> for BTreeMap<K, V> {
1689 fn extend<I: IntoIterator<Item = (&'a K, &'a V)>>(&mut self, iter: I) {
1690 self.extend(iter.into_iter().map(|(&key, &value)| (key, value)));
1694 #[stable(feature = "rust1", since = "1.0.0")]
1695 impl<K: Hash, V: Hash> Hash for BTreeMap<K, V> {
1696 fn hash<H: Hasher>(&self, state: &mut H) {
1703 #[stable(feature = "rust1", since = "1.0.0")]
1704 impl<K: Ord, V> Default for BTreeMap<K, V> {
1705 /// Creates an empty `BTreeMap<K, V>`.
1706 fn default() -> BTreeMap<K, V> {
1711 #[stable(feature = "rust1", since = "1.0.0")]
1712 impl<K: PartialEq, V: PartialEq> PartialEq for BTreeMap<K, V> {
1713 fn eq(&self, other: &BTreeMap<K, V>) -> bool {
1714 self.len() == other.len() && self.iter().zip(other).all(|(a, b)| a == b)
1718 #[stable(feature = "rust1", since = "1.0.0")]
1719 impl<K: Eq, V: Eq> Eq for BTreeMap<K, V> {}
1721 #[stable(feature = "rust1", since = "1.0.0")]
1722 impl<K: PartialOrd, V: PartialOrd> PartialOrd for BTreeMap<K, V> {
1724 fn partial_cmp(&self, other: &BTreeMap<K, V>) -> Option<Ordering> {
1725 self.iter().partial_cmp(other.iter())
1729 #[stable(feature = "rust1", since = "1.0.0")]
1730 impl<K: Ord, V: Ord> Ord for BTreeMap<K, V> {
1732 fn cmp(&self, other: &BTreeMap<K, V>) -> Ordering {
1733 self.iter().cmp(other.iter())
1737 #[stable(feature = "rust1", since = "1.0.0")]
1738 impl<K: Debug, V: Debug> Debug for BTreeMap<K, V> {
1739 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1740 f.debug_map().entries(self.iter()).finish()
1744 #[stable(feature = "rust1", since = "1.0.0")]
1745 impl<'a, K: Ord, Q: ?Sized, V> Index<&'a Q> for BTreeMap<K, V>
1751 /// Returns a reference to the value corresponding to the supplied key.
1755 /// Panics if the key is not present in the `BTreeMap`.
1757 fn index(&self, key: &Q) -> &V {
1758 self.get(key).expect("no entry found for key")
1762 fn first_leaf_edge<BorrowType, K, V>
1763 (mut node: NodeRef<BorrowType, K, V, marker::LeafOrInternal>)
1764 -> Handle<NodeRef<BorrowType, K, V, marker::Leaf>, marker::Edge> {
1766 match node.force() {
1767 Leaf(leaf) => return leaf.first_edge(),
1768 Internal(internal) => {
1769 node = internal.first_edge().descend();
1775 fn last_leaf_edge<BorrowType, K, V>
1776 (mut node: NodeRef<BorrowType, K, V, marker::LeafOrInternal>)
1777 -> Handle<NodeRef<BorrowType, K, V, marker::Leaf>, marker::Edge> {
1779 match node.force() {
1780 Leaf(leaf) => return leaf.last_edge(),
1781 Internal(internal) => {
1782 node = internal.last_edge().descend();
1788 fn range_search<BorrowType, K, V, Q: ?Sized, R: RangeArgument<Q>>(
1789 root1: NodeRef<BorrowType, K, V, marker::LeafOrInternal>,
1790 root2: NodeRef<BorrowType, K, V, marker::LeafOrInternal>,
1792 )-> (Handle<NodeRef<BorrowType, K, V, marker::Leaf>, marker::Edge>,
1793 Handle<NodeRef<BorrowType, K, V, marker::Leaf>, marker::Edge>)
1794 where Q: Ord, K: Borrow<Q>
1796 match (range.start(), range.end()) {
1797 (Excluded(s), Excluded(e)) if s==e =>
1798 panic!("range start and end are equal and excluded in BTreeMap"),
1799 (Included(s), Included(e)) |
1800 (Included(s), Excluded(e)) |
1801 (Excluded(s), Included(e)) |
1802 (Excluded(s), Excluded(e)) if s>e =>
1803 panic!("range start is greater than range end in BTreeMap"),
1807 let mut min_node = root1;
1808 let mut max_node = root2;
1809 let mut min_found = false;
1810 let mut max_found = false;
1811 let mut diverged = false;
1814 let min_edge = match (min_found, range.start()) {
1815 (false, Included(key)) => match search::search_linear(&min_node, key) {
1816 (i, true) => { min_found = true; i },
1819 (false, Excluded(key)) => match search::search_linear(&min_node, key) {
1820 (i, true) => { min_found = true; i+1 },
1823 (_, Unbounded) => 0,
1824 (true, Included(_)) => min_node.keys().len(),
1825 (true, Excluded(_)) => 0,
1828 let max_edge = match (max_found, range.end()) {
1829 (false, Included(key)) => match search::search_linear(&max_node, key) {
1830 (i, true) => { max_found = true; i+1 },
1833 (false, Excluded(key)) => match search::search_linear(&max_node, key) {
1834 (i, true) => { max_found = true; i },
1837 (_, Unbounded) => max_node.keys().len(),
1838 (true, Included(_)) => 0,
1839 (true, Excluded(_)) => max_node.keys().len(),
1843 if max_edge < min_edge { panic!("Ord is ill-defined in BTreeMap range") }
1844 if min_edge != max_edge { diverged = true; }
1847 let front = Handle::new_edge(min_node, min_edge);
1848 let back = Handle::new_edge(max_node, max_edge);
1849 match (front.force(), back.force()) {
1850 (Leaf(f), Leaf(b)) => {
1853 (Internal(min_int), Internal(max_int)) => {
1854 min_node = min_int.descend();
1855 max_node = max_int.descend();
1857 _ => unreachable!("BTreeMap has different depths"),
1863 unsafe fn unwrap_unchecked<T>(val: Option<T>) -> T {
1864 val.unwrap_or_else(|| {
1865 if cfg!(debug_assertions) {
1866 panic!("'unchecked' unwrap on None in BTreeMap");
1868 intrinsics::unreachable();
1873 impl<K, V> BTreeMap<K, V> {
1874 /// Gets an iterator over the entries of the map, sorted by key.
1881 /// use std::collections::BTreeMap;
1883 /// let mut map = BTreeMap::new();
1884 /// map.insert(3, "c");
1885 /// map.insert(2, "b");
1886 /// map.insert(1, "a");
1888 /// for (key, value) in map.iter() {
1889 /// println!("{}: {}", key, value);
1892 /// let (first_key, first_value) = map.iter().next().unwrap();
1893 /// assert_eq!((*first_key, *first_value), (1, "a"));
1895 #[stable(feature = "rust1", since = "1.0.0")]
1896 pub fn iter(&self) -> Iter<K, V> {
1899 front: first_leaf_edge(self.root.as_ref()),
1900 back: last_leaf_edge(self.root.as_ref()),
1902 length: self.length,
1906 /// Gets a mutable iterator over the entries of the map, sorted by key.
1913 /// use std::collections::BTreeMap;
1915 /// let mut map = BTreeMap::new();
1916 /// map.insert("a", 1);
1917 /// map.insert("b", 2);
1918 /// map.insert("c", 3);
1920 /// // add 10 to the value if the key isn't "a"
1921 /// for (key, value) in map.iter_mut() {
1922 /// if key != &"a" {
1927 #[stable(feature = "rust1", since = "1.0.0")]
1928 pub fn iter_mut(&mut self) -> IterMut<K, V> {
1929 let root1 = self.root.as_mut();
1930 let root2 = unsafe { ptr::read(&root1) };
1933 front: first_leaf_edge(root1),
1934 back: last_leaf_edge(root2),
1935 _marker: PhantomData,
1937 length: self.length,
1941 /// Gets an iterator over the keys of the map, in sorted order.
1948 /// use std::collections::BTreeMap;
1950 /// let mut a = BTreeMap::new();
1951 /// a.insert(2, "b");
1952 /// a.insert(1, "a");
1954 /// let keys: Vec<_> = a.keys().cloned().collect();
1955 /// assert_eq!(keys, [1, 2]);
1957 #[stable(feature = "rust1", since = "1.0.0")]
1958 pub fn keys<'a>(&'a self) -> Keys<'a, K, V> {
1959 Keys { inner: self.iter() }
1962 /// Gets an iterator over the values of the map, in order by key.
1969 /// use std::collections::BTreeMap;
1971 /// let mut a = BTreeMap::new();
1972 /// a.insert(1, "hello");
1973 /// a.insert(2, "goodbye");
1975 /// let values: Vec<&str> = a.values().cloned().collect();
1976 /// assert_eq!(values, ["hello", "goodbye"]);
1978 #[stable(feature = "rust1", since = "1.0.0")]
1979 pub fn values<'a>(&'a self) -> Values<'a, K, V> {
1980 Values { inner: self.iter() }
1983 /// Gets a mutable iterator over the values of the map, in order by key.
1990 /// use std::collections::BTreeMap;
1992 /// let mut a = BTreeMap::new();
1993 /// a.insert(1, String::from("hello"));
1994 /// a.insert(2, String::from("goodbye"));
1996 /// for value in a.values_mut() {
1997 /// value.push_str("!");
2000 /// let values: Vec<String> = a.values().cloned().collect();
2001 /// assert_eq!(values, [String::from("hello!"),
2002 /// String::from("goodbye!")]);
2004 #[stable(feature = "map_values_mut", since = "1.10.0")]
2005 pub fn values_mut(&mut self) -> ValuesMut<K, V> {
2006 ValuesMut { inner: self.iter_mut() }
2009 /// Returns the number of elements in the map.
2016 /// use std::collections::BTreeMap;
2018 /// let mut a = BTreeMap::new();
2019 /// assert_eq!(a.len(), 0);
2020 /// a.insert(1, "a");
2021 /// assert_eq!(a.len(), 1);
2023 #[stable(feature = "rust1", since = "1.0.0")]
2024 pub fn len(&self) -> usize {
2028 /// Returns `true` if the map contains no elements.
2035 /// use std::collections::BTreeMap;
2037 /// let mut a = BTreeMap::new();
2038 /// assert!(a.is_empty());
2039 /// a.insert(1, "a");
2040 /// assert!(!a.is_empty());
2042 #[stable(feature = "rust1", since = "1.0.0")]
2043 pub fn is_empty(&self) -> bool {
2048 impl<'a, K: Ord, V> Entry<'a, K, V> {
2049 /// Ensures a value is in the entry by inserting the default if empty, and returns
2050 /// a mutable reference to the value in the entry.
2055 /// use std::collections::BTreeMap;
2057 /// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
2058 /// map.entry("poneyland").or_insert(12);
2060 /// assert_eq!(map["poneyland"], 12);
2062 #[stable(feature = "rust1", since = "1.0.0")]
2063 pub fn or_insert(self, default: V) -> &'a mut V {
2065 Occupied(entry) => entry.into_mut(),
2066 Vacant(entry) => entry.insert(default),
2070 /// Ensures a value is in the entry by inserting the result of the default function if empty,
2071 /// and returns a mutable reference to the value in the entry.
2076 /// use std::collections::BTreeMap;
2078 /// let mut map: BTreeMap<&str, String> = BTreeMap::new();
2079 /// let s = "hoho".to_string();
2081 /// map.entry("poneyland").or_insert_with(|| s);
2083 /// assert_eq!(map["poneyland"], "hoho".to_string());
2085 #[stable(feature = "rust1", since = "1.0.0")]
2086 pub fn or_insert_with<F: FnOnce() -> V>(self, default: F) -> &'a mut V {
2088 Occupied(entry) => entry.into_mut(),
2089 Vacant(entry) => entry.insert(default()),
2093 /// Returns a reference to this entry's key.
2098 /// use std::collections::BTreeMap;
2100 /// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
2101 /// assert_eq!(map.entry("poneyland").key(), &"poneyland");
2103 #[stable(feature = "map_entry_keys", since = "1.10.0")]
2104 pub fn key(&self) -> &K {
2106 Occupied(ref entry) => entry.key(),
2107 Vacant(ref entry) => entry.key(),
2111 /// Provides in-place mutable access to an occupied entry before any
2112 /// potential inserts into the map.
2117 /// use std::collections::BTreeMap;
2119 /// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
2121 /// map.entry("poneyland")
2122 /// .and_modify(|e| { *e += 1 })
2124 /// assert_eq!(map["poneyland"], 42);
2126 /// map.entry("poneyland")
2127 /// .and_modify(|e| { *e += 1 })
2129 /// assert_eq!(map["poneyland"], 43);
2131 #[stable(feature = "entry_and_modify", since = "1.26.0")]
2132 pub fn and_modify<F>(self, mut f: F) -> Self
2133 where F: FnMut(&mut V)
2136 Occupied(mut entry) => {
2140 Vacant(entry) => Vacant(entry),
2145 impl<'a, K: Ord, V: Default> Entry<'a, K, V> {
2146 #[unstable(feature = "entry_or_default", issue = "44324")]
2147 /// Ensures a value is in the entry by inserting the default value if empty,
2148 /// and returns a mutable reference to the value in the entry.
2153 /// #![feature(entry_or_default)]
2155 /// use std::collections::BTreeMap;
2157 /// let mut map: BTreeMap<&str, Option<usize>> = BTreeMap::new();
2158 /// map.entry("poneyland").or_default();
2160 /// assert_eq!(map["poneyland"], None);
2163 pub fn or_default(self) -> &'a mut V {
2165 Occupied(entry) => entry.into_mut(),
2166 Vacant(entry) => entry.insert(Default::default()),
2172 impl<'a, K: Ord, V> VacantEntry<'a, K, V> {
2173 /// Gets a reference to the key that would be used when inserting a value
2174 /// through the VacantEntry.
2179 /// use std::collections::BTreeMap;
2181 /// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
2182 /// assert_eq!(map.entry("poneyland").key(), &"poneyland");
2184 #[stable(feature = "map_entry_keys", since = "1.10.0")]
2185 pub fn key(&self) -> &K {
2189 /// Take ownership of the key.
2194 /// use std::collections::BTreeMap;
2195 /// use std::collections::btree_map::Entry;
2197 /// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
2199 /// if let Entry::Vacant(v) = map.entry("poneyland") {
2203 #[stable(feature = "map_entry_recover_keys2", since = "1.12.0")]
2204 pub fn into_key(self) -> K {
2208 /// Sets the value of the entry with the `VacantEntry`'s key,
2209 /// and returns a mutable reference to it.
2214 /// use std::collections::BTreeMap;
2216 /// let mut count: BTreeMap<&str, usize> = BTreeMap::new();
2218 /// // count the number of occurrences of letters in the vec
2219 /// for x in vec!["a","b","a","c","a","b"] {
2220 /// *count.entry(x).or_insert(0) += 1;
2223 /// assert_eq!(count["a"], 3);
2225 #[stable(feature = "rust1", since = "1.0.0")]
2226 pub fn insert(self, value: V) -> &'a mut V {
2235 let mut cur_parent = match self.handle.insert(self.key, value) {
2236 (Fit(handle), _) => return handle.into_kv_mut().1,
2237 (Split(left, k, v, right), ptr) => {
2242 left.ascend().map_err(|n| n.into_root_mut())
2249 match parent.insert(ins_k, ins_v, ins_edge) {
2250 Fit(_) => return unsafe { &mut *out_ptr },
2251 Split(left, k, v, right) => {
2255 cur_parent = left.ascend().map_err(|n| n.into_root_mut());
2260 root.push_level().push(ins_k, ins_v, ins_edge);
2261 return unsafe { &mut *out_ptr };
2268 impl<'a, K: Ord, V> OccupiedEntry<'a, K, V> {
2269 /// Gets a reference to the key in the entry.
2274 /// use std::collections::BTreeMap;
2276 /// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
2277 /// map.entry("poneyland").or_insert(12);
2278 /// assert_eq!(map.entry("poneyland").key(), &"poneyland");
2280 #[stable(feature = "map_entry_keys", since = "1.10.0")]
2281 pub fn key(&self) -> &K {
2282 self.handle.reborrow().into_kv().0
2285 /// Take ownership of the key and value from the map.
2290 /// use std::collections::BTreeMap;
2291 /// use std::collections::btree_map::Entry;
2293 /// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
2294 /// map.entry("poneyland").or_insert(12);
2296 /// if let Entry::Occupied(o) = map.entry("poneyland") {
2297 /// // We delete the entry from the map.
2298 /// o.remove_entry();
2301 /// // If now try to get the value, it will panic:
2302 /// // println!("{}", map["poneyland"]);
2304 #[stable(feature = "map_entry_recover_keys2", since = "1.12.0")]
2305 pub fn remove_entry(self) -> (K, V) {
2309 /// Gets a reference to the value in the entry.
2314 /// use std::collections::BTreeMap;
2315 /// use std::collections::btree_map::Entry;
2317 /// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
2318 /// map.entry("poneyland").or_insert(12);
2320 /// if let Entry::Occupied(o) = map.entry("poneyland") {
2321 /// assert_eq!(o.get(), &12);
2324 #[stable(feature = "rust1", since = "1.0.0")]
2325 pub fn get(&self) -> &V {
2326 self.handle.reborrow().into_kv().1
2329 /// Gets a mutable reference to the value in the entry.
2334 /// use std::collections::BTreeMap;
2335 /// use std::collections::btree_map::Entry;
2337 /// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
2338 /// map.entry("poneyland").or_insert(12);
2340 /// assert_eq!(map["poneyland"], 12);
2341 /// if let Entry::Occupied(mut o) = map.entry("poneyland") {
2342 /// *o.get_mut() += 10;
2344 /// assert_eq!(map["poneyland"], 22);
2346 #[stable(feature = "rust1", since = "1.0.0")]
2347 pub fn get_mut(&mut self) -> &mut V {
2348 self.handle.kv_mut().1
2351 /// Converts the entry into a mutable reference to its value.
2356 /// use std::collections::BTreeMap;
2357 /// use std::collections::btree_map::Entry;
2359 /// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
2360 /// map.entry("poneyland").or_insert(12);
2362 /// assert_eq!(map["poneyland"], 12);
2363 /// if let Entry::Occupied(o) = map.entry("poneyland") {
2364 /// *o.into_mut() += 10;
2366 /// assert_eq!(map["poneyland"], 22);
2368 #[stable(feature = "rust1", since = "1.0.0")]
2369 pub fn into_mut(self) -> &'a mut V {
2370 self.handle.into_kv_mut().1
2373 /// Sets the value of the entry with the `OccupiedEntry`'s key,
2374 /// and returns the entry's old value.
2379 /// use std::collections::BTreeMap;
2380 /// use std::collections::btree_map::Entry;
2382 /// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
2383 /// map.entry("poneyland").or_insert(12);
2385 /// if let Entry::Occupied(mut o) = map.entry("poneyland") {
2386 /// assert_eq!(o.insert(15), 12);
2388 /// assert_eq!(map["poneyland"], 15);
2390 #[stable(feature = "rust1", since = "1.0.0")]
2391 pub fn insert(&mut self, value: V) -> V {
2392 mem::replace(self.get_mut(), value)
2395 /// Takes the value of the entry out of the map, and returns it.
2400 /// use std::collections::BTreeMap;
2401 /// use std::collections::btree_map::Entry;
2403 /// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
2404 /// map.entry("poneyland").or_insert(12);
2406 /// if let Entry::Occupied(o) = map.entry("poneyland") {
2407 /// assert_eq!(o.remove(), 12);
2409 /// // If we try to get "poneyland"'s value, it'll panic:
2410 /// // println!("{}", map["poneyland"]);
2412 #[stable(feature = "rust1", since = "1.0.0")]
2413 pub fn remove(self) -> V {
2417 fn remove_kv(self) -> (K, V) {
2420 let (small_leaf, old_key, old_val) = match self.handle.force() {
2422 let (hole, old_key, old_val) = leaf.remove();
2423 (hole.into_node(), old_key, old_val)
2425 Internal(mut internal) => {
2426 let key_loc = internal.kv_mut().0 as *mut K;
2427 let val_loc = internal.kv_mut().1 as *mut V;
2429 let to_remove = first_leaf_edge(internal.right_edge().descend()).right_kv().ok();
2430 let to_remove = unsafe { unwrap_unchecked(to_remove) };
2432 let (hole, key, val) = to_remove.remove();
2434 let old_key = unsafe { mem::replace(&mut *key_loc, key) };
2435 let old_val = unsafe { mem::replace(&mut *val_loc, val) };
2437 (hole.into_node(), old_key, old_val)
2442 let mut cur_node = small_leaf.forget_type();
2443 while cur_node.len() < node::CAPACITY / 2 {
2444 match handle_underfull_node(cur_node) {
2446 EmptyParent(_) => unreachable!(),
2448 if parent.len() == 0 {
2449 // We must be at the root
2450 parent.into_root_mut().pop_level();
2453 cur_node = parent.forget_type();
2464 enum UnderflowResult<'a, K, V> {
2466 EmptyParent(NodeRef<marker::Mut<'a>, K, V, marker::Internal>),
2467 Merged(NodeRef<marker::Mut<'a>, K, V, marker::Internal>),
2468 Stole(NodeRef<marker::Mut<'a>, K, V, marker::Internal>),
2471 fn handle_underfull_node<'a, K, V>(node: NodeRef<marker::Mut<'a>, K, V, marker::LeafOrInternal>)
2472 -> UnderflowResult<'a, K, V> {
2473 let parent = if let Ok(parent) = node.ascend() {
2479 let (is_left, mut handle) = match parent.left_kv() {
2480 Ok(left) => (true, left),
2482 match parent.right_kv() {
2483 Ok(right) => (false, right),
2485 return EmptyParent(parent.into_node());
2491 if handle.can_merge() {
2492 Merged(handle.merge().into_node())
2495 handle.steal_left();
2497 handle.steal_right();
2499 Stole(handle.into_node())
2503 impl<K: Ord, V, I: Iterator<Item = (K, V)>> Iterator for MergeIter<K, V, I> {
2506 fn next(&mut self) -> Option<(K, V)> {
2507 let res = match (self.left.peek(), self.right.peek()) {
2508 (Some(&(ref left_key, _)), Some(&(ref right_key, _))) => left_key.cmp(right_key),
2509 (Some(_), None) => Ordering::Less,
2510 (None, Some(_)) => Ordering::Greater,
2511 (None, None) => return None,
2514 // Check which elements comes first and only advance the corresponding iterator.
2515 // If two keys are equal, take the value from `right`.
2517 Ordering::Less => self.left.next(),
2518 Ordering::Greater => self.right.next(),
2519 Ordering::Equal => {