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 #[unstable(feature = "fused", issue = "35602")]
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 #[unstable(feature = "fused", issue = "35602")]
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 #[unstable(feature = "fused", issue = "35602")]
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 #[unstable(feature = "fused", issue = "35602")]
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 #[unstable(feature = "fused", issue = "35602")]
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 #[unstable(feature = "fused", issue = "35602")]
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 #[unstable(feature = "fused", issue = "35602")]
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 #[unstable(feature = "fused", issue = "35602")]
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
>
1752 fn index(&self, key
: &Q
) -> &V
{
1753 self.get(key
).expect("no entry found for key")
1757 fn first_leaf_edge
<BorrowType
, K
, V
>
1758 (mut node
: NodeRef
<BorrowType
, K
, V
, marker
::LeafOrInternal
>)
1759 -> Handle
<NodeRef
<BorrowType
, K
, V
, marker
::Leaf
>, marker
::Edge
> {
1761 match node
.force() {
1762 Leaf(leaf
) => return leaf
.first_edge(),
1763 Internal(internal
) => {
1764 node
= internal
.first_edge().descend();
1770 fn last_leaf_edge
<BorrowType
, K
, V
>
1771 (mut node
: NodeRef
<BorrowType
, K
, V
, marker
::LeafOrInternal
>)
1772 -> Handle
<NodeRef
<BorrowType
, K
, V
, marker
::Leaf
>, marker
::Edge
> {
1774 match node
.force() {
1775 Leaf(leaf
) => return leaf
.last_edge(),
1776 Internal(internal
) => {
1777 node
= internal
.last_edge().descend();
1783 fn range_search
<BorrowType
, K
, V
, Q
: ?Sized
, R
: RangeArgument
<Q
>>(
1784 root1
: NodeRef
<BorrowType
, K
, V
, marker
::LeafOrInternal
>,
1785 root2
: NodeRef
<BorrowType
, K
, V
, marker
::LeafOrInternal
>,
1787 )-> (Handle
<NodeRef
<BorrowType
, K
, V
, marker
::Leaf
>, marker
::Edge
>,
1788 Handle
<NodeRef
<BorrowType
, K
, V
, marker
::Leaf
>, marker
::Edge
>)
1789 where Q
: Ord
, K
: Borrow
<Q
>
1791 match (range
.start(), range
.end()) {
1792 (Excluded(s
), Excluded(e
)) if s
==e
=>
1793 panic
!("range start and end are equal and excluded in BTreeMap"),
1794 (Included(s
), Included(e
)) |
1795 (Included(s
), Excluded(e
)) |
1796 (Excluded(s
), Included(e
)) |
1797 (Excluded(s
), Excluded(e
)) if s
>e
=>
1798 panic
!("range start is greater than range end in BTreeMap"),
1802 let mut min_node
= root1
;
1803 let mut max_node
= root2
;
1804 let mut min_found
= false;
1805 let mut max_found
= false;
1806 let mut diverged
= false;
1809 let min_edge
= match (min_found
, range
.start()) {
1810 (false, Included(key
)) => match search
::search_linear(&min_node
, key
) {
1811 (i
, true) => { min_found = true; i }
,
1814 (false, Excluded(key
)) => match search
::search_linear(&min_node
, key
) {
1815 (i
, true) => { min_found = true; i+1 }
,
1818 (_
, Unbounded
) => 0,
1819 (true, Included(_
)) => min_node
.keys().len(),
1820 (true, Excluded(_
)) => 0,
1823 let max_edge
= match (max_found
, range
.end()) {
1824 (false, Included(key
)) => match search
::search_linear(&max_node
, key
) {
1825 (i
, true) => { max_found = true; i+1 }
,
1828 (false, Excluded(key
)) => match search
::search_linear(&max_node
, key
) {
1829 (i
, true) => { max_found = true; i }
,
1832 (_
, Unbounded
) => max_node
.keys().len(),
1833 (true, Included(_
)) => 0,
1834 (true, Excluded(_
)) => max_node
.keys().len(),
1838 if max_edge
< min_edge { panic!("Ord is ill-defined in BTreeMap range") }
1839 if min_edge
!= max_edge { diverged = true; }
1842 let front
= Handle
::new_edge(min_node
, min_edge
);
1843 let back
= Handle
::new_edge(max_node
, max_edge
);
1844 match (front
.force(), back
.force()) {
1845 (Leaf(f
), Leaf(b
)) => {
1848 (Internal(min_int
), Internal(max_int
)) => {
1849 min_node
= min_int
.descend();
1850 max_node
= max_int
.descend();
1852 _
=> unreachable
!("BTreeMap has different depths"),
1858 unsafe fn unwrap_unchecked
<T
>(val
: Option
<T
>) -> T
{
1859 val
.unwrap_or_else(|| {
1860 if cfg
!(debug_assertions
) {
1861 panic
!("'unchecked' unwrap on None in BTreeMap");
1863 intrinsics
::unreachable();
1868 impl<K
, V
> BTreeMap
<K
, V
> {
1869 /// Gets an iterator over the entries of the map, sorted by key.
1876 /// use std::collections::BTreeMap;
1878 /// let mut map = BTreeMap::new();
1879 /// map.insert(3, "c");
1880 /// map.insert(2, "b");
1881 /// map.insert(1, "a");
1883 /// for (key, value) in map.iter() {
1884 /// println!("{}: {}", key, value);
1887 /// let (first_key, first_value) = map.iter().next().unwrap();
1888 /// assert_eq!((*first_key, *first_value), (1, "a"));
1890 #[stable(feature = "rust1", since = "1.0.0")]
1891 pub fn iter(&self) -> Iter
<K
, V
> {
1894 front
: first_leaf_edge(self.root
.as_ref()),
1895 back
: last_leaf_edge(self.root
.as_ref()),
1897 length
: self.length
,
1901 /// Gets a mutable iterator over the entries of the map, sorted by key.
1908 /// use std::collections::BTreeMap;
1910 /// let mut map = BTreeMap::new();
1911 /// map.insert("a", 1);
1912 /// map.insert("b", 2);
1913 /// map.insert("c", 3);
1915 /// // add 10 to the value if the key isn't "a"
1916 /// for (key, value) in map.iter_mut() {
1917 /// if key != &"a" {
1922 #[stable(feature = "rust1", since = "1.0.0")]
1923 pub fn iter_mut(&mut self) -> IterMut
<K
, V
> {
1924 let root1
= self.root
.as_mut();
1925 let root2
= unsafe { ptr::read(&root1) }
;
1928 front
: first_leaf_edge(root1
),
1929 back
: last_leaf_edge(root2
),
1930 _marker
: PhantomData
,
1932 length
: self.length
,
1936 /// Gets an iterator over the keys of the map, in sorted order.
1943 /// use std::collections::BTreeMap;
1945 /// let mut a = BTreeMap::new();
1946 /// a.insert(2, "b");
1947 /// a.insert(1, "a");
1949 /// let keys: Vec<_> = a.keys().cloned().collect();
1950 /// assert_eq!(keys, [1, 2]);
1952 #[stable(feature = "rust1", since = "1.0.0")]
1953 pub fn keys
<'a
>(&'a
self) -> Keys
<'a
, K
, V
> {
1954 Keys { inner: self.iter() }
1957 /// Gets an iterator over the values of the map, in order by key.
1964 /// use std::collections::BTreeMap;
1966 /// let mut a = BTreeMap::new();
1967 /// a.insert(1, "hello");
1968 /// a.insert(2, "goodbye");
1970 /// let values: Vec<&str> = a.values().cloned().collect();
1971 /// assert_eq!(values, ["hello", "goodbye"]);
1973 #[stable(feature = "rust1", since = "1.0.0")]
1974 pub fn values
<'a
>(&'a
self) -> Values
<'a
, K
, V
> {
1975 Values { inner: self.iter() }
1978 /// Gets a mutable iterator over the values of the map, in order by key.
1985 /// use std::collections::BTreeMap;
1987 /// let mut a = BTreeMap::new();
1988 /// a.insert(1, String::from("hello"));
1989 /// a.insert(2, String::from("goodbye"));
1991 /// for value in a.values_mut() {
1992 /// value.push_str("!");
1995 /// let values: Vec<String> = a.values().cloned().collect();
1996 /// assert_eq!(values, [String::from("hello!"),
1997 /// String::from("goodbye!")]);
1999 #[stable(feature = "map_values_mut", since = "1.10.0")]
2000 pub fn values_mut(&mut self) -> ValuesMut
<K
, V
> {
2001 ValuesMut { inner: self.iter_mut() }
2004 /// Returns the number of elements in the map.
2011 /// use std::collections::BTreeMap;
2013 /// let mut a = BTreeMap::new();
2014 /// assert_eq!(a.len(), 0);
2015 /// a.insert(1, "a");
2016 /// assert_eq!(a.len(), 1);
2018 #[stable(feature = "rust1", since = "1.0.0")]
2019 pub fn len(&self) -> usize {
2023 /// Returns `true` if the map contains no elements.
2030 /// use std::collections::BTreeMap;
2032 /// let mut a = BTreeMap::new();
2033 /// assert!(a.is_empty());
2034 /// a.insert(1, "a");
2035 /// assert!(!a.is_empty());
2037 #[stable(feature = "rust1", since = "1.0.0")]
2038 pub fn is_empty(&self) -> bool
{
2043 impl<'a
, K
: Ord
, V
> Entry
<'a
, K
, V
> {
2044 /// Ensures a value is in the entry by inserting the default if empty, and returns
2045 /// a mutable reference to the value in the entry.
2050 /// use std::collections::BTreeMap;
2052 /// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
2053 /// map.entry("poneyland").or_insert(12);
2055 /// assert_eq!(map["poneyland"], 12);
2057 #[stable(feature = "rust1", since = "1.0.0")]
2058 pub fn or_insert(self, default: V
) -> &'a
mut V
{
2060 Occupied(entry
) => entry
.into_mut(),
2061 Vacant(entry
) => entry
.insert(default),
2065 /// Ensures a value is in the entry by inserting the result of the default function if empty,
2066 /// and returns a mutable reference to the value in the entry.
2071 /// use std::collections::BTreeMap;
2073 /// let mut map: BTreeMap<&str, String> = BTreeMap::new();
2074 /// let s = "hoho".to_string();
2076 /// map.entry("poneyland").or_insert_with(|| s);
2078 /// assert_eq!(map["poneyland"], "hoho".to_string());
2080 #[stable(feature = "rust1", since = "1.0.0")]
2081 pub fn or_insert_with
<F
: FnOnce() -> V
>(self, default: F
) -> &'a
mut V
{
2083 Occupied(entry
) => entry
.into_mut(),
2084 Vacant(entry
) => entry
.insert(default()),
2088 /// Returns a reference to this entry's key.
2093 /// use std::collections::BTreeMap;
2095 /// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
2096 /// assert_eq!(map.entry("poneyland").key(), &"poneyland");
2098 #[stable(feature = "map_entry_keys", since = "1.10.0")]
2099 pub fn key(&self) -> &K
{
2101 Occupied(ref entry
) => entry
.key(),
2102 Vacant(ref entry
) => entry
.key(),
2106 /// Provides in-place mutable access to an occupied entry before any
2107 /// potential inserts into the map.
2112 /// #![feature(entry_and_modify)]
2113 /// use std::collections::BTreeMap;
2115 /// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
2117 /// map.entry("poneyland")
2118 /// .and_modify(|e| { *e += 1 })
2120 /// assert_eq!(map["poneyland"], 42);
2122 /// map.entry("poneyland")
2123 /// .and_modify(|e| { *e += 1 })
2125 /// assert_eq!(map["poneyland"], 43);
2127 #[unstable(feature = "entry_and_modify", issue = "44733")]
2128 pub fn and_modify
<F
>(self, mut f
: F
) -> Self
2129 where F
: FnMut(&mut V
)
2132 Occupied(mut entry
) => {
2136 Vacant(entry
) => Vacant(entry
),
2141 impl<'a
, K
: Ord
, V
: Default
> Entry
<'a
, K
, V
> {
2142 #[unstable(feature = "entry_or_default", issue = "44324")]
2143 /// Ensures a value is in the entry by inserting the default value if empty,
2144 /// and returns a mutable reference to the value in the entry.
2149 /// #![feature(entry_or_default)]
2151 /// use std::collections::BTreeMap;
2153 /// let mut map: BTreeMap<&str, Option<usize>> = BTreeMap::new();
2154 /// map.entry("poneyland").or_default();
2156 /// assert_eq!(map["poneyland"], None);
2159 pub fn or_default(self) -> &'a
mut V
{
2161 Occupied(entry
) => entry
.into_mut(),
2162 Vacant(entry
) => entry
.insert(Default
::default()),
2168 impl<'a
, K
: Ord
, V
> VacantEntry
<'a
, K
, V
> {
2169 /// Gets a reference to the key that would be used when inserting a value
2170 /// through the VacantEntry.
2175 /// use std::collections::BTreeMap;
2177 /// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
2178 /// assert_eq!(map.entry("poneyland").key(), &"poneyland");
2180 #[stable(feature = "map_entry_keys", since = "1.10.0")]
2181 pub fn key(&self) -> &K
{
2185 /// Take ownership of the key.
2190 /// use std::collections::BTreeMap;
2191 /// use std::collections::btree_map::Entry;
2193 /// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
2195 /// if let Entry::Vacant(v) = map.entry("poneyland") {
2199 #[stable(feature = "map_entry_recover_keys2", since = "1.12.0")]
2200 pub fn into_key(self) -> K
{
2204 /// Sets the value of the entry with the `VacantEntry`'s key,
2205 /// and returns a mutable reference to it.
2210 /// use std::collections::BTreeMap;
2212 /// let mut count: BTreeMap<&str, usize> = BTreeMap::new();
2214 /// // count the number of occurrences of letters in the vec
2215 /// for x in vec!["a","b","a","c","a","b"] {
2216 /// *count.entry(x).or_insert(0) += 1;
2219 /// assert_eq!(count["a"], 3);
2221 #[stable(feature = "rust1", since = "1.0.0")]
2222 pub fn insert(self, value
: V
) -> &'a
mut V
{
2231 let mut cur_parent
= match self.handle
.insert(self.key
, value
) {
2232 (Fit(handle
), _
) => return handle
.into_kv_mut().1,
2233 (Split(left
, k
, v
, right
), ptr
) => {
2238 left
.ascend().map_err(|n
| n
.into_root_mut())
2245 match parent
.insert(ins_k
, ins_v
, ins_edge
) {
2246 Fit(_
) => return unsafe { &mut *out_ptr }
,
2247 Split(left
, k
, v
, right
) => {
2251 cur_parent
= left
.ascend().map_err(|n
| n
.into_root_mut());
2256 root
.push_level().push(ins_k
, ins_v
, ins_edge
);
2257 return unsafe { &mut *out_ptr }
;
2264 impl<'a
, K
: Ord
, V
> OccupiedEntry
<'a
, K
, V
> {
2265 /// Gets a reference to the key in the entry.
2270 /// use std::collections::BTreeMap;
2272 /// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
2273 /// map.entry("poneyland").or_insert(12);
2274 /// assert_eq!(map.entry("poneyland").key(), &"poneyland");
2276 #[stable(feature = "map_entry_keys", since = "1.10.0")]
2277 pub fn key(&self) -> &K
{
2278 self.handle
.reborrow().into_kv().0
2281 /// Take ownership of the key and value from the map.
2286 /// use std::collections::BTreeMap;
2287 /// use std::collections::btree_map::Entry;
2289 /// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
2290 /// map.entry("poneyland").or_insert(12);
2292 /// if let Entry::Occupied(o) = map.entry("poneyland") {
2293 /// // We delete the entry from the map.
2294 /// o.remove_entry();
2297 /// // If now try to get the value, it will panic:
2298 /// // println!("{}", map["poneyland"]);
2300 #[stable(feature = "map_entry_recover_keys2", since = "1.12.0")]
2301 pub fn remove_entry(self) -> (K
, V
) {
2305 /// Gets a reference to the value in the entry.
2310 /// use std::collections::BTreeMap;
2311 /// use std::collections::btree_map::Entry;
2313 /// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
2314 /// map.entry("poneyland").or_insert(12);
2316 /// if let Entry::Occupied(o) = map.entry("poneyland") {
2317 /// assert_eq!(o.get(), &12);
2320 #[stable(feature = "rust1", since = "1.0.0")]
2321 pub fn get(&self) -> &V
{
2322 self.handle
.reborrow().into_kv().1
2325 /// Gets a mutable reference to the value in the entry.
2330 /// use std::collections::BTreeMap;
2331 /// use std::collections::btree_map::Entry;
2333 /// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
2334 /// map.entry("poneyland").or_insert(12);
2336 /// assert_eq!(map["poneyland"], 12);
2337 /// if let Entry::Occupied(mut o) = map.entry("poneyland") {
2338 /// *o.get_mut() += 10;
2340 /// assert_eq!(map["poneyland"], 22);
2342 #[stable(feature = "rust1", since = "1.0.0")]
2343 pub fn get_mut(&mut self) -> &mut V
{
2344 self.handle
.kv_mut().1
2347 /// Converts the entry into a mutable reference to its value.
2352 /// use std::collections::BTreeMap;
2353 /// use std::collections::btree_map::Entry;
2355 /// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
2356 /// map.entry("poneyland").or_insert(12);
2358 /// assert_eq!(map["poneyland"], 12);
2359 /// if let Entry::Occupied(o) = map.entry("poneyland") {
2360 /// *o.into_mut() += 10;
2362 /// assert_eq!(map["poneyland"], 22);
2364 #[stable(feature = "rust1", since = "1.0.0")]
2365 pub fn into_mut(self) -> &'a
mut V
{
2366 self.handle
.into_kv_mut().1
2369 /// Sets the value of the entry with the `OccupiedEntry`'s key,
2370 /// and returns the entry's old value.
2375 /// use std::collections::BTreeMap;
2376 /// use std::collections::btree_map::Entry;
2378 /// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
2379 /// map.entry("poneyland").or_insert(12);
2381 /// if let Entry::Occupied(mut o) = map.entry("poneyland") {
2382 /// assert_eq!(o.insert(15), 12);
2384 /// assert_eq!(map["poneyland"], 15);
2386 #[stable(feature = "rust1", since = "1.0.0")]
2387 pub fn insert(&mut self, value
: V
) -> V
{
2388 mem
::replace(self.get_mut(), value
)
2391 /// Takes the value of the entry out of the map, and returns it.
2396 /// use std::collections::BTreeMap;
2397 /// use std::collections::btree_map::Entry;
2399 /// let mut map: BTreeMap<&str, usize> = BTreeMap::new();
2400 /// map.entry("poneyland").or_insert(12);
2402 /// if let Entry::Occupied(o) = map.entry("poneyland") {
2403 /// assert_eq!(o.remove(), 12);
2405 /// // If we try to get "poneyland"'s value, it'll panic:
2406 /// // println!("{}", map["poneyland"]);
2408 #[stable(feature = "rust1", since = "1.0.0")]
2409 pub fn remove(self) -> V
{
2413 fn remove_kv(self) -> (K
, V
) {
2416 let (small_leaf
, old_key
, old_val
) = match self.handle
.force() {
2418 let (hole
, old_key
, old_val
) = leaf
.remove();
2419 (hole
.into_node(), old_key
, old_val
)
2421 Internal(mut internal
) => {
2422 let key_loc
= internal
.kv_mut().0 as *mut K
;
2423 let val_loc
= internal
.kv_mut().1 as *mut V
;
2425 let to_remove
= first_leaf_edge(internal
.right_edge().descend()).right_kv().ok();
2426 let to_remove
= unsafe { unwrap_unchecked(to_remove) }
;
2428 let (hole
, key
, val
) = to_remove
.remove();
2430 let old_key
= unsafe { mem::replace(&mut *key_loc, key) }
;
2431 let old_val
= unsafe { mem::replace(&mut *val_loc, val) }
;
2433 (hole
.into_node(), old_key
, old_val
)
2438 let mut cur_node
= small_leaf
.forget_type();
2439 while cur_node
.len() < node
::CAPACITY
/ 2 {
2440 match handle_underfull_node(cur_node
) {
2442 EmptyParent(_
) => unreachable
!(),
2444 if parent
.len() == 0 {
2445 // We must be at the root
2446 parent
.into_root_mut().pop_level();
2449 cur_node
= parent
.forget_type();
2460 enum UnderflowResult
<'a
, K
, V
> {
2462 EmptyParent(NodeRef
<marker
::Mut
<'a
>, K
, V
, marker
::Internal
>),
2463 Merged(NodeRef
<marker
::Mut
<'a
>, K
, V
, marker
::Internal
>),
2464 Stole(NodeRef
<marker
::Mut
<'a
>, K
, V
, marker
::Internal
>),
2467 fn handle_underfull_node
<'a
, K
, V
>(node
: NodeRef
<marker
::Mut
<'a
>, K
, V
, marker
::LeafOrInternal
>)
2468 -> UnderflowResult
<'a
, K
, V
> {
2469 let parent
= if let Ok(parent
) = node
.ascend() {
2475 let (is_left
, mut handle
) = match parent
.left_kv() {
2476 Ok(left
) => (true, left
),
2478 match parent
.right_kv() {
2479 Ok(right
) => (false, right
),
2481 return EmptyParent(parent
.into_node());
2487 if handle
.can_merge() {
2488 Merged(handle
.merge().into_node())
2491 handle
.steal_left();
2493 handle
.steal_right();
2495 Stole(handle
.into_node())
2499 impl<K
: Ord
, V
, I
: Iterator
<Item
= (K
, V
)>> Iterator
for MergeIter
<K
, V
, I
> {
2502 fn next(&mut self) -> Option
<(K
, V
)> {
2503 let res
= match (self.left
.peek(), self.right
.peek()) {
2504 (Some(&(ref left_key
, _
)), Some(&(ref right_key
, _
))) => left_key
.cmp(right_key
),
2505 (Some(_
), None
) => Ordering
::Less
,
2506 (None
, Some(_
)) => Ordering
::Greater
,
2507 (None
, None
) => return None
,
2510 // Check which elements comes first and only advance the corresponding iterator.
2511 // If two keys are equal, take the value from `right`.
2513 Ordering
::Less
=> self.left
.next(),
2514 Ordering
::Greater
=> self.right
.next(),
2515 Ordering
::Equal
=> {