1 // Copyright 2014 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 // This implementation is largely based on the high-level description and analysis of B-Trees
12 // found in *Open Data Structures* (ODS). Although our implementation does not use any of
13 // the source found in ODS, if one wishes to review the high-level design of this structure, it
14 // can be freely downloaded at http://opendatastructures.org/. Its contents are as of this
15 // writing (August 2014) freely licensed under the following Creative Commons Attribution
16 // License: [CC BY 2.5 CA](http://creativecommons.org/licenses/by/2.5/ca/).
18 pub use self::Entry::*;
22 use core::borrow::BorrowFrom;
23 use core::cmp::Ordering;
24 use core::default::Default;
26 use core::hash::{Writer, Hash};
27 use core::iter::{Map, FromIterator};
28 use core::ops::{Index, IndexMut};
29 use core::{iter, fmt, mem};
31 use ring_buf::RingBuf;
33 use self::Continuation::{Continue, Finished};
35 use super::node::ForceResult::{Leaf, Internal};
36 use super::node::TraversalItem::{mod, Elem, Edge};
37 use super::node::{Traversal, MutTraversal, MoveTraversal};
38 use super::node::{mod, Node, Found, GoDown};
40 // FIXME(conventions): implement bounded iterators
42 /// A map based on a B-Tree.
44 /// B-Trees represent a fundamental compromise between cache-efficiency and actually minimizing
45 /// the amount of work performed in a search. In theory, a binary search tree (BST) is the optimal
46 /// choice for a sorted map, as a perfectly balanced BST performs the theoretical minimum amount of
47 /// comparisons necessary to find an element (log<sub>2</sub>n). However, in practice the way this
48 /// is done is *very* inefficient for modern computer architectures. In particular, every element
49 /// is stored in its own individually heap-allocated node. This means that every single insertion
50 /// triggers a heap-allocation, and every single comparison should be a cache-miss. Since these
51 /// are both notably expensive things to do in practice, we are forced to at very least reconsider
54 /// A B-Tree instead makes each node contain B-1 to 2B-1 elements in a contiguous array. By doing
55 /// this, we reduce the number of allocations by a factor of B, and improve cache efficiency in
56 /// searches. However, this does mean that searches will have to do *more* comparisons on average.
57 /// The precise number of comparisons depends on the node search strategy used. For optimal cache
58 /// efficiency, one could search the nodes linearly. For optimal comparisons, one could search
59 /// the node using binary search. As a compromise, one could also perform a linear search
60 /// that initially only checks every i<sup>th</sup> element for some choice of i.
62 /// Currently, our implementation simply performs naive linear search. This provides excellent
63 /// performance on *small* nodes of elements which are cheap to compare. However in the future we
64 /// would like to further explore choosing the optimal search strategy based on the choice of B,
65 /// and possibly other factors. Using linear search, searching for a random element is expected
66 /// to take O(B log<sub>B</sub>n) comparisons, which is generally worse than a BST. In practice,
67 /// however, performance is excellent. `BTreeMap` is able to readily outperform `TreeMap` under
68 /// many workloads, and is competitive where it doesn't. BTreeMap also generally *scales* better
69 /// than TreeMap, making it more appropriate for large datasets.
71 /// However, `TreeMap` may still be more appropriate to use in many contexts. If elements are very
72 /// large or expensive to compare, `TreeMap` may be more appropriate. It won't allocate any
73 /// more space than is needed, and will perform the minimal number of comparisons necessary.
74 /// `TreeMap` also provides much better performance stability guarantees. Generally, very few
75 /// changes need to be made to update a BST, and two updates are expected to take about the same
76 /// amount of time on roughly equal sized BSTs. However a B-Tree's performance is much more
77 /// amortized. If a node is overfull, it must be split into two nodes. If a node is underfull, it
78 /// may be merged with another. Both of these operations are relatively expensive to perform, and
79 /// it's possible to force one to occur at every single level of the tree in a single insertion or
80 /// deletion. In fact, a malicious or otherwise unlucky sequence of insertions and deletions can
81 /// force this degenerate behaviour to occur on every operation. While the total amount of work
82 /// done on each operation isn't *catastrophic*, and *is* still bounded by O(B log<sub>B</sub>n),
83 /// it is certainly much slower when it does.
86 pub struct BTreeMap<K, V> {
93 /// An abstract base over-which all other BTree iterators are built.
101 /// An iterator over a BTreeMap's entries.
103 pub struct Iter<'a, K: 'a, V: 'a> {
104 inner: AbsIter<Traversal<'a, K, V>>
107 /// A mutable iterator over a BTreeMap's entries.
109 pub struct IterMut<'a, K: 'a, V: 'a> {
110 inner: AbsIter<MutTraversal<'a, K, V>>
113 /// An owning iterator over a BTreeMap's entries.
115 pub struct IntoIter<K, V> {
116 inner: AbsIter<MoveTraversal<K, V>>
119 /// An iterator over a BTreeMap's keys.
121 pub struct Keys<'a, K: 'a, V: 'a> {
122 inner: Map<(&'a K, &'a V), &'a K, Iter<'a, K, V>, fn((&'a K, &'a V)) -> &'a K>
125 /// An iterator over a BTreeMap's values.
127 pub struct Values<'a, K: 'a, V: 'a> {
128 inner: Map<(&'a K, &'a V), &'a V, Iter<'a, K, V>, fn((&'a K, &'a V)) -> &'a V>
131 /// A view into a single entry in a map, which may either be vacant or occupied.
132 pub enum Entry<'a, K:'a, V:'a> {
134 Vacant(VacantEntry<'a, K, V>),
135 /// An occupied Entry
136 Occupied(OccupiedEntry<'a, K, V>),
140 pub struct VacantEntry<'a, K:'a, V:'a> {
142 stack: stack::SearchStack<'a, K, V, node::handle::Edge, node::handle::Leaf>,
145 /// An occupied Entry.
146 pub struct OccupiedEntry<'a, K:'a, V:'a> {
147 stack: stack::SearchStack<'a, K, V, node::handle::KV, node::handle::LeafOrInternal>,
150 impl<K: Ord, V> BTreeMap<K, V> {
151 /// Makes a new empty BTreeMap with a reasonable choice for B.
153 pub fn new() -> BTreeMap<K, V> {
154 //FIXME(Gankro): Tune this as a function of size_of<K/V>?
158 /// Makes a new empty BTreeMap with the given B.
160 /// B cannot be less than 2.
161 pub fn with_b(b: uint) -> BTreeMap<K, V> {
162 assert!(b > 1, "B must be greater than 1");
166 root: Node::make_leaf_root(b),
171 /// Clears the map, removing all values.
176 /// use std::collections::BTreeMap;
178 /// let mut a = BTreeMap::new();
179 /// a.insert(1u, "a");
181 /// assert!(a.is_empty());
184 pub fn clear(&mut self) {
186 // avoid recursive destructors by manually traversing the tree
187 for _ in mem::replace(self, BTreeMap::with_b(b)).into_iter() {};
190 /// Deprecated: renamed to `get`.
191 #[deprecated = "renamed to `get`"]
192 pub fn find(&self, key: &K) -> Option<&V> {
196 // Searching in a B-Tree is pretty straightforward.
198 // Start at the root. Try to find the key in the current node. If we find it, return it.
199 // If it's not in there, follow the edge *before* the smallest key larger than
200 // the search key. If no such key exists (they're *all* smaller), then just take the last
201 // edge in the node. If we're in a leaf and we don't find our key, then it's not
204 /// Returns a reference to the value corresponding to the key.
206 /// The key may be any borrowed form of the map's key type, but the ordering
207 /// on the borrowed form *must* match the ordering on the key type.
212 /// use std::collections::BTreeMap;
214 /// let mut map = BTreeMap::new();
215 /// map.insert(1u, "a");
216 /// assert_eq!(map.get(&1), Some(&"a"));
217 /// assert_eq!(map.get(&2), None);
220 pub fn get<Sized? Q>(&self, key: &Q) -> Option<&V> where Q: BorrowFrom<K> + Ord {
221 let mut cur_node = &self.root;
223 match Node::search(cur_node, key) {
224 Found(handle) => return Some(handle.into_kv().1),
225 GoDown(handle) => match handle.force() {
226 Leaf(_) => return None,
227 Internal(internal_handle) => {
228 cur_node = internal_handle.into_edge();
236 /// Returns true if the map contains a value for the specified key.
238 /// The key may be any borrowed form of the map's key type, but the ordering
239 /// on the borrowed form *must* match the ordering on the key type.
244 /// use std::collections::BTreeMap;
246 /// let mut map = BTreeMap::new();
247 /// map.insert(1u, "a");
248 /// assert_eq!(map.contains_key(&1), true);
249 /// assert_eq!(map.contains_key(&2), false);
252 pub fn contains_key<Sized? Q>(&self, key: &Q) -> bool where Q: BorrowFrom<K> + Ord {
253 self.get(key).is_some()
256 /// Deprecated: renamed to `get_mut`.
257 #[deprecated = "renamed to `get_mut`"]
258 pub fn find_mut(&mut self, key: &K) -> Option<&mut V> {
262 /// Returns a mutable reference to the value corresponding to the key.
264 /// The key may be any borrowed form of the map's key type, but the ordering
265 /// on the borrowed form *must* match the ordering on the key type.
270 /// use std::collections::BTreeMap;
272 /// let mut map = BTreeMap::new();
273 /// map.insert(1u, "a");
274 /// match map.get_mut(&1) {
275 /// Some(x) => *x = "b",
278 /// assert_eq!(map[1], "b");
280 // See `get` for implementation notes, this is basically a copy-paste with mut's added
282 pub fn get_mut<Sized? Q>(&mut self, key: &Q) -> Option<&mut V> where Q: BorrowFrom<K> + Ord {
283 // temp_node is a Borrowck hack for having a mutable value outlive a loop iteration
284 let mut temp_node = &mut self.root;
286 let cur_node = temp_node;
287 match Node::search(cur_node, key) {
288 Found(handle) => return Some(handle.into_kv_mut().1),
289 GoDown(handle) => match handle.force() {
290 Leaf(_) => return None,
291 Internal(internal_handle) => {
292 temp_node = internal_handle.into_edge_mut();
300 /// Deprecated: renamed to `insert`.
301 #[deprecated = "renamed to `insert`"]
302 pub fn swap(&mut self, key: K, value: V) -> Option<V> {
303 self.insert(key, value)
306 // Insertion in a B-Tree is a bit complicated.
308 // First we do the same kind of search described in `find`. But we need to maintain a stack of
309 // all the nodes/edges in our search path. If we find a match for the key we're trying to
310 // insert, just swap the vals and return the old ones. However, when we bottom out in a leaf,
311 // we attempt to insert our key-value pair at the same location we would want to follow another
314 // If the node has room, then this is done in the obvious way by shifting elements. However,
315 // if the node itself is full, we split node into two, and give its median key-value
316 // pair to its parent to insert the new node with. Of course, the parent may also be
317 // full, and insertion can propagate until we reach the root. If we reach the root, and
318 // it is *also* full, then we split the root and place the two nodes under a newly made root.
320 // Note that we subtly deviate from Open Data Structures in our implementation of split.
321 // ODS describes inserting into the node *regardless* of its capacity, and then
322 // splitting *afterwards* if it happens to be overfull. However, this is inefficient.
323 // Instead, we split beforehand, and then insert the key-value pair into the appropriate
324 // result node. This has two consequences:
326 // 1) While ODS produces a left node of size B-1, and a right node of size B,
327 // we may potentially reverse this. However, this shouldn't effect the analysis.
329 // 2) While ODS may potentially return the pair we *just* inserted after
330 // the split, we will never do this. Again, this shouldn't effect the analysis.
332 /// Inserts a key-value pair from the map. If the key already had a value
333 /// present in the map, that value is returned. Otherwise, `None` is returned.
338 /// use std::collections::BTreeMap;
340 /// let mut map = BTreeMap::new();
341 /// assert_eq!(map.insert(37u, "a"), None);
342 /// assert_eq!(map.is_empty(), false);
344 /// map.insert(37, "b");
345 /// assert_eq!(map.insert(37, "c"), Some("b"));
346 /// assert_eq!(map[37], "c");
349 pub fn insert(&mut self, mut key: K, mut value: V) -> Option<V> {
350 // This is a stack of rawptrs to nodes paired with indices, respectively
351 // representing the nodes and edges of our search path. We have to store rawptrs
352 // because as far as Rust is concerned, we can mutate aliased data with such a
353 // stack. It is of course correct, but what it doesn't know is that we will only
354 // be popping and using these ptrs one at a time in child-to-parent order. The alternative
355 // to doing this is to take the Nodes from their parents. This actually makes
356 // borrowck *really* happy and everything is pretty smooth. However, this creates
357 // *tons* of pointless writes, and requires us to always walk all the way back to
358 // the root after an insertion, even if we only needed to change a leaf. Therefore,
359 // we accept this potential unsafety and complexity in the name of performance.
361 // Regardless, the actual dangerous logic is completely abstracted away from BTreeMap
362 // by the stack module. All it can do is immutably read nodes, and ask the search stack
363 // to proceed down some edge by index. This makes the search logic we'll be reusing in a
364 // few different methods much neater, and of course drastically improves safety.
365 let mut stack = stack::PartialSearchStack::new(self);
368 let result = stack.with(move |pusher, node| {
369 // Same basic logic as found in `find`, but with PartialSearchStack mediating the
370 // actual nodes for us
371 return match Node::search(node, &key) {
372 Found(mut handle) => {
373 // Perfect match, swap the values and return the old one
374 mem::swap(handle.val_mut(), &mut value);
375 Finished(Some(value))
378 // We need to keep searching, try to get the search stack
379 // to go down further
380 match handle.force() {
381 Leaf(leaf_handle) => {
382 // We've reached a leaf, perform the insertion here
383 pusher.seal(leaf_handle).insert(key, value);
386 Internal(internal_handle) => {
387 // We've found the subtree to insert this key/value pair in,
389 Continue((pusher.push(internal_handle), key, value))
396 Finished(ret) => { return ret; },
397 Continue((new_stack, renewed_key, renewed_val)) => {
406 // Deletion is the most complicated operation for a B-Tree.
408 // First we do the same kind of search described in
409 // `find`. But we need to maintain a stack of all the nodes/edges in our search path.
410 // If we don't find the key, then we just return `None` and do nothing. If we do find the
411 // key, we perform two operations: remove the item, and then possibly handle underflow.
413 // # removing the item
414 // If the node is a leaf, we just remove the item, and shift
415 // any items after it back to fill the hole.
417 // If the node is an internal node, we *swap* the item with the smallest item in
418 // in its right subtree (which must reside in a leaf), and then revert to the leaf
421 // # handling underflow
422 // After removing an item, there may be too few items in the node. We want nodes
423 // to be mostly full for efficiency, although we make an exception for the root, which
424 // may have as few as one item. If this is the case, we may first try to steal
425 // an item from our left or right neighbour.
427 // To steal from the left (right) neighbour,
428 // we take the largest (smallest) item and child from it. We then swap the taken item
429 // with the item in their mutual parent that separates them, and then insert the
430 // parent's item and the taken child into the first (last) index of the underflowed node.
432 // However, stealing has the possibility of underflowing our neighbour. If this is the
433 // case, we instead *merge* with our neighbour. This of course reduces the number of
434 // children in the parent. Therefore, we also steal the item that separates the now
435 // merged nodes, and insert it into the merged node.
437 // Merging may cause the parent to underflow. If this is the case, then we must repeat
438 // the underflow handling process on the parent. If merging merges the last two children
439 // of the root, then we replace the root with the merged node.
441 /// Deprecated: renamed to `remove`.
442 #[deprecated = "renamed to `remove`"]
443 pub fn pop(&mut self, key: &K) -> Option<V> {
447 /// Removes a key from the map, returning the value at the key if the key
448 /// was previously in the map.
450 /// The key may be any borrowed form of the map's key type, but the ordering
451 /// on the borrowed form *must* match the ordering on the key type.
456 /// use std::collections::BTreeMap;
458 /// let mut map = BTreeMap::new();
459 /// map.insert(1u, "a");
460 /// assert_eq!(map.remove(&1), Some("a"));
461 /// assert_eq!(map.remove(&1), None);
464 pub fn remove<Sized? Q>(&mut self, key: &Q) -> Option<V> where Q: BorrowFrom<K> + Ord {
465 // See `swap` for a more thorough description of the stuff going on in here
466 let mut stack = stack::PartialSearchStack::new(self);
468 let result = stack.with(move |pusher, node| {
469 return match Node::search(node, key) {
471 // Perfect match. Terminate the stack here, and remove the entry
472 Finished(Some(pusher.seal(handle).remove()))
475 // We need to keep searching, try to go down the next edge
476 match handle.force() {
477 // We're at a leaf; the key isn't in here
478 Leaf(_) => Finished(None),
479 Internal(internal_handle) => Continue(pusher.push(internal_handle))
485 Finished(ret) => return ret,
486 Continue(new_stack) => stack = new_stack
492 /// A helper enum useful for deciding whether to continue a loop since we can't
493 /// return from a closure
494 enum Continuation<A, B> {
499 /// The stack module provides a safe interface for constructing and manipulating a stack of ptrs
500 /// to nodes. By using this module much better safety guarantees can be made, and more search
501 /// boilerplate gets cut out.
503 use core::prelude::*;
504 use core::kinds::marker;
506 use core::ops::{Deref, DerefMut};
508 use super::super::node::{mod, Node, Fit, Split, Internal, Leaf};
509 use super::super::node::handle;
512 /// A generic mutable reference, identical to `&mut` except for the fact that its lifetime
513 /// parameter is invariant. This means that wherever an `IdRef` is expected, only an `IdRef`
514 /// with the exact requested lifetime can be used. This is in contrast to normal references,
515 /// where `&'static` can be used in any function expecting any lifetime reference.
516 pub struct IdRef<'id, T: 'id> {
518 marker: marker::InvariantLifetime<'id>
521 impl<'id, T> Deref for IdRef<'id, T> {
524 fn deref(&self) -> &T {
529 impl<'id, T> DerefMut for IdRef<'id, T> {
530 fn deref_mut(&mut self) -> &mut T {
535 type StackItem<K, V> = node::Handle<*mut Node<K, V>, handle::Edge, handle::Internal>;
536 type Stack<K, V> = Vec<StackItem<K, V>>;
538 /// A `PartialSearchStack` handles the construction of a search stack.
539 pub struct PartialSearchStack<'a, K:'a, V:'a> {
540 map: &'a mut BTreeMap<K, V>,
542 next: *mut Node<K, V>,
545 /// A `SearchStack` represents a full path to an element or an edge of interest. It provides
546 /// methods depending on the type of what the path points to for removing an element, inserting
547 /// a new element, and manipulating to element at the top of the stack.
548 pub struct SearchStack<'a, K:'a, V:'a, Type, NodeType> {
549 map: &'a mut BTreeMap<K, V>,
551 top: node::Handle<*mut Node<K, V>, Type, NodeType>,
554 /// A `PartialSearchStack` that doesn't hold a a reference to the next node, and is just
555 /// just waiting for a `Handle` to that next node to be pushed. See `PartialSearchStack::with`
556 /// for more details.
557 pub struct Pusher<'id, 'a, K:'a, V:'a> {
558 map: &'a mut BTreeMap<K, V>,
560 marker: marker::InvariantLifetime<'id>
563 impl<'a, K, V> PartialSearchStack<'a, K, V> {
564 /// Creates a new PartialSearchStack from a BTreeMap by initializing the stack with the
565 /// root of the tree.
566 pub fn new(map: &'a mut BTreeMap<K, V>) -> PartialSearchStack<'a, K, V> {
567 let depth = map.depth;
570 next: &mut map.root as *mut _,
572 stack: Vec::with_capacity(depth),
576 /// Breaks up the stack into a `Pusher` and the next `Node`, allowing the given closure
577 /// to interact with, search, and finally push the `Node` onto the stack. The passed in
578 /// closure must be polymorphic on the `'id` lifetime parameter, as this statically
579 /// ensures that only `Handle`s from the correct `Node` can be pushed.
581 /// The reason this works is that the `Pusher` has an `'id` parameter, and will only accept
582 /// handles with the same `'id`. The closure could only get references with that lifetime
583 /// through its arguments or through some other `IdRef` that it has lying around. However,
584 /// no other `IdRef` could possibly work - because the `'id` is held in an invariant
585 /// parameter, it would need to have precisely the correct lifetime, which would mean that
586 /// at least one of the calls to `with` wouldn't be properly polymorphic, wanting a
587 /// specific lifetime instead of the one that `with` chooses to give it.
589 /// See also Haskell's `ST` monad, which uses a similar trick.
590 pub fn with<T, F: for<'id> FnOnce(Pusher<'id, 'a, K, V>,
591 IdRef<'id, Node<K, V>>) -> T>(self, closure: F) -> T {
592 let pusher = Pusher {
595 marker: marker::InvariantLifetime
598 inner: unsafe { &mut *self.next },
599 marker: marker::InvariantLifetime
602 closure(pusher, node)
606 impl<'id, 'a, K, V> Pusher<'id, 'a, K, V> {
607 /// Pushes the requested child of the stack's current top on top of the stack. If the child
608 /// exists, then a new PartialSearchStack is yielded. Otherwise, a VacantSearchStack is
610 pub fn push(mut self, mut edge: node::Handle<IdRef<'id, Node<K, V>>,
613 -> PartialSearchStack<'a, K, V> {
614 self.stack.push(edge.as_raw());
618 next: edge.edge_mut() as *mut _,
622 /// Converts the PartialSearchStack into a SearchStack.
623 pub fn seal<Type, NodeType>
624 (self, mut handle: node::Handle<IdRef<'id, Node<K, V>>, Type, NodeType>)
625 -> SearchStack<'a, K, V, Type, NodeType> {
629 top: handle.as_raw(),
634 impl<'a, K, V, NodeType> SearchStack<'a, K, V, handle::KV, NodeType> {
635 /// Gets a reference to the value the stack points to.
636 pub fn peek(&self) -> &V {
637 unsafe { self.top.from_raw().into_kv().1 }
640 /// Gets a mutable reference to the value the stack points to.
641 pub fn peek_mut(&mut self) -> &mut V {
642 unsafe { self.top.from_raw_mut().into_kv_mut().1 }
645 /// Converts the stack into a mutable reference to the value it points to, with a lifetime
646 /// tied to the original tree.
647 pub fn into_top(mut self) -> &'a mut V {
649 mem::copy_mut_lifetime(
651 self.top.from_raw_mut().val_mut()
657 impl<'a, K, V> SearchStack<'a, K, V, handle::KV, handle::Leaf> {
658 /// Removes the key and value in the top element of the stack, then handles underflows as
659 /// described in BTree's pop function.
660 fn remove_leaf(mut self) -> V {
661 self.map.length -= 1;
663 // Remove the key-value pair from the leaf that this search stack points to.
664 // Then, note if the leaf is underfull, and promptly forget the leaf and its ptr
665 // to avoid ownership issues.
666 let (value, mut underflow) = unsafe {
667 let (_, value) = self.top.from_raw_mut().remove_as_leaf();
668 let underflow = self.top.from_raw().node().is_underfull();
673 match self.stack.pop() {
675 // We've reached the root, so no matter what, we're done. We manually
676 // access the root via the tree itself to avoid creating any dangling
678 if self.map.root.len() == 0 && !self.map.root.is_leaf() {
679 // We've emptied out the root, so make its only child the new root.
680 // If it's a leaf, we just let it become empty.
682 self.map.root.hoist_lone_child();
686 Some(mut handle) => {
688 // Underflow! Handle it!
690 handle.from_raw_mut().handle_underflow();
691 underflow = handle.from_raw().node().is_underfull();
703 impl<'a, K, V> SearchStack<'a, K, V, handle::KV, handle::LeafOrInternal> {
704 /// Removes the key and value in the top element of the stack, then handles underflows as
705 /// described in BTree's pop function.
706 pub fn remove(self) -> V {
707 // Ensure that the search stack goes to a leaf. This is necessary to perform deletion
708 // in a BTree. Note that this may put the tree in an inconsistent state (further
709 // described in into_leaf's comments), but this is immediately fixed by the
710 // removing the value we want to remove
711 self.into_leaf().remove_leaf()
714 /// Subroutine for removal. Takes a search stack for a key that might terminate at an
715 /// internal node, and mutates the tree and search stack to *make* it a search stack
716 /// for that same key that *does* terminates at a leaf. If the mutation occurs, then this
717 /// leaves the tree in an inconsistent state that must be repaired by the caller by
718 /// removing the entry in question. Specifically the key-value pair and its successor will
720 fn into_leaf(mut self) -> SearchStack<'a, K, V, handle::KV, handle::Leaf> {
722 let mut top_raw = self.top;
723 let mut top = top_raw.from_raw_mut();
725 let key_ptr = top.key_mut() as *mut _;
726 let val_ptr = top.val_mut() as *mut _;
728 // Try to go into the right subtree of the found key to find its successor
730 Leaf(mut leaf_handle) => {
731 // We're a proper leaf stack, nothing to do
735 top: leaf_handle.as_raw()
738 Internal(mut internal_handle) => {
739 let mut right_handle = internal_handle.right_edge();
741 //We're not a proper leaf stack, let's get to work.
742 self.stack.push(right_handle.as_raw());
744 let mut temp_node = right_handle.edge_mut();
746 // Walk into the smallest subtree of this node
747 let node = temp_node;
749 match node.kv_handle(0).force() {
750 Leaf(mut handle) => {
751 // This node is a leaf, do the swap and return
752 mem::swap(handle.key_mut(), &mut *key_ptr);
753 mem::swap(handle.val_mut(), &mut *val_ptr);
760 Internal(kv_handle) => {
761 // This node is internal, go deeper
762 let mut handle = kv_handle.into_left_edge();
763 self.stack.push(handle.as_raw());
764 temp_node = handle.into_edge_mut();
774 impl<'a, K, V> SearchStack<'a, K, V, handle::Edge, handle::Leaf> {
775 /// Inserts the key and value into the top element in the stack, and if that node has to
776 /// split recursively inserts the split contents into the next element stack until
779 /// Assumes that the stack represents a search path from the root to a leaf.
781 /// An &mut V is returned to the inserted value, for callers that want a reference to this.
782 pub fn insert(mut self, key: K, val: V) -> &'a mut V {
784 self.map.length += 1;
786 // Insert the key and value into the leaf at the top of the stack
787 let (mut insertion, inserted_ptr) = self.top.from_raw_mut()
788 .insert_as_leaf(key, val);
793 // The last insertion went off without a hitch, no splits! We can stop
795 return &mut *inserted_ptr;
797 Split(key, val, right) => match self.stack.pop() {
798 // The last insertion triggered a split, so get the next element on the
799 // stack to recursively insert the split node into.
801 // The stack was empty; we've split the root, and need to make a
802 // a new one. This is done in-place because we can't move the
803 // root out of a reference to the tree.
804 Node::make_internal_root(&mut self.map.root, self.map.b,
808 return &mut *inserted_ptr;
810 Some(mut handle) => {
811 // The stack wasn't empty, do the insertion and recurse
812 insertion = handle.from_raw_mut()
813 .insert_as_internal(key, val, right);
825 impl<K: Ord, V> FromIterator<(K, V)> for BTreeMap<K, V> {
826 fn from_iter<T: Iterator<Item=(K, V)>>(iter: T) -> BTreeMap<K, V> {
827 let mut map = BTreeMap::new();
834 impl<K: Ord, V> Extend<(K, V)> for BTreeMap<K, V> {
836 fn extend<T: Iterator<Item=(K, V)>>(&mut self, mut iter: T) {
844 impl<S: Writer, K: Hash<S>, V: Hash<S>> Hash<S> for BTreeMap<K, V> {
845 fn hash(&self, state: &mut S) {
846 for elt in self.iter() {
853 impl<K: Ord, V> Default for BTreeMap<K, V> {
855 fn default() -> BTreeMap<K, V> {
861 impl<K: PartialEq, V: PartialEq> PartialEq for BTreeMap<K, V> {
862 fn eq(&self, other: &BTreeMap<K, V>) -> bool {
863 self.len() == other.len() &&
864 self.iter().zip(other.iter()).all(|(a, b)| a == b)
869 impl<K: Eq, V: Eq> Eq for BTreeMap<K, V> {}
872 impl<K: PartialOrd, V: PartialOrd> PartialOrd for BTreeMap<K, V> {
874 fn partial_cmp(&self, other: &BTreeMap<K, V>) -> Option<Ordering> {
875 iter::order::partial_cmp(self.iter(), other.iter())
880 impl<K: Ord, V: Ord> Ord for BTreeMap<K, V> {
882 fn cmp(&self, other: &BTreeMap<K, V>) -> Ordering {
883 iter::order::cmp(self.iter(), other.iter())
888 impl<K: Show, V: Show> Show for BTreeMap<K, V> {
889 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
890 try!(write!(f, "{{"));
892 for (i, (k, v)) in self.iter().enumerate() {
893 if i != 0 { try!(write!(f, ", ")); }
894 try!(write!(f, "{}: {}", *k, *v));
901 // NOTE(stage0): remove impl after a snapshot
904 impl<K: Ord, Sized? Q, V> Index<Q, V> for BTreeMap<K, V>
905 where Q: BorrowFrom<K> + Ord
907 fn index(&self, key: &Q) -> &V {
908 self.get(key).expect("no entry found for key")
912 #[cfg(not(stage0))] // NOTE(stage0): remove cfg after a snapshot
914 impl<K: Ord, Sized? Q, V> Index<Q> for BTreeMap<K, V>
915 where Q: BorrowFrom<K> + Ord
919 fn index(&self, key: &Q) -> &V {
920 self.get(key).expect("no entry found for key")
924 // NOTE(stage0): remove impl after a snapshot
927 impl<K: Ord, Sized? Q, V> IndexMut<Q, V> for BTreeMap<K, V>
928 where Q: BorrowFrom<K> + Ord
930 fn index_mut(&mut self, key: &Q) -> &mut V {
931 self.get_mut(key).expect("no entry found for key")
935 #[cfg(not(stage0))] // NOTE(stage0): remove cfg after a snapshot
937 impl<K: Ord, Sized? Q, V> IndexMut<Q> for BTreeMap<K, V>
938 where Q: BorrowFrom<K> + Ord
942 fn index_mut(&mut self, key: &Q) -> &mut V {
943 self.get_mut(key).expect("no entry found for key")
947 /// Genericises over how to get the correct type of iterator from the correct type
948 /// of Node ownership.
950 fn traverse(node: N) -> Self;
953 impl<'a, K, V> Traverse<&'a Node<K, V>> for Traversal<'a, K, V> {
954 fn traverse(node: &'a Node<K, V>) -> Traversal<'a, K, V> {
959 impl<'a, K, V> Traverse<&'a mut Node<K, V>> for MutTraversal<'a, K, V> {
960 fn traverse(node: &'a mut Node<K, V>) -> MutTraversal<'a, K, V> {
965 impl<K, V> Traverse<Node<K, V>> for MoveTraversal<K, V> {
966 fn traverse(node: Node<K, V>) -> MoveTraversal<K, V> {
971 /// Represents an operation to perform inside the following iterator methods.
972 /// This is necessary to use in `next` because we want to modify self.left inside
973 /// a match that borrows it. Similarly, in `next_back` for self.right. Instead, we use this
974 /// enum to note what we want to do, and do it after the match.
980 impl<K, V, E, T> Iterator for AbsIter<T> where
981 T: DoubleEndedIterator + Iterator<Item=TraversalItem<K, V, E>> + Traverse<E>,
985 // This function is pretty long, but only because there's a lot of cases to consider.
986 // Our iterator represents two search paths, left and right, to the smallest and largest
987 // elements we have yet to yield. lca represents the least common ancestor of these two paths,
988 // above-which we never walk, since everything outside it has already been consumed (or was
989 // never in the range to iterate).
991 // Note that the design of these iterators permits an *arbitrary* initial pair of min and max,
992 // making these arbitrary sub-range iterators. However the logic to construct these paths
993 // efficiently is fairly involved, so this is a FIXME. The sub-range iterators also wouldn't be
994 // able to accurately predict size, so those iterators can't implement ExactSizeIterator.
995 fn next(&mut self) -> Option<(K, V)> {
997 // We want the smallest element, so try to get the top of the left stack
998 let op = match self.left.back_mut() {
999 // The left stack is empty, so try to get the next element of the two paths
1000 // LCAs (the left search path is currently a subpath of the right one)
1001 None => match self.lca.next() {
1002 // The lca has been exhausted, walk further down the right path
1003 None => match self.right.pop_front() {
1004 // The right path is exhausted, so we're done
1005 None => return None,
1006 // The right path had something, make that the new LCA
1007 // and restart the whole process
1013 // The lca yielded an edge, make that the new head of the left path
1014 Some(Edge(next)) => Push(Traverse::traverse(next)),
1015 // The lca yielded an entry, so yield that
1016 Some(Elem(k, v)) => {
1021 // The left stack wasn't empty, so continue along the node in its head
1022 Some(iter) => match iter.next() {
1023 // The head of the left path is empty, so Pop it off and restart the process
1025 // The head of the left path yielded an edge, so make that the new head
1027 Some(Edge(next)) => Push(Traverse::traverse(next)),
1028 // The head of the left path yielded entry, so yield that
1029 Some(Elem(k, v)) => {
1036 // Handle any operation on the left stack as necessary
1038 Push(item) => { self.left.push_back(item); },
1039 Pop => { self.left.pop_back(); },
1044 fn size_hint(&self) -> (uint, Option<uint>) {
1045 (self.size, Some(self.size))
1049 impl<K, V, E, T> DoubleEndedIterator for AbsIter<T> where
1050 T: DoubleEndedIterator + Iterator<Item=TraversalItem<K, V, E>> + Traverse<E>,
1052 // next_back is totally symmetric to next
1053 fn next_back(&mut self) -> Option<(K, V)> {
1055 let op = match self.right.back_mut() {
1056 None => match self.lca.next_back() {
1057 None => match self.left.pop_front() {
1058 None => return None,
1064 Some(Edge(next)) => Push(Traverse::traverse(next)),
1065 Some(Elem(k, v)) => {
1070 Some(iter) => match iter.next_back() {
1072 Some(Edge(next)) => Push(Traverse::traverse(next)),
1073 Some(Elem(k, v)) => {
1081 Push(item) => { self.right.push_back(item); },
1082 Pop => { self.right.pop_back(); }
1089 impl<'a, K, V> Iterator for Iter<'a, K, V> {
1090 type Item = (&'a K, &'a V);
1092 fn next(&mut self) -> Option<(&'a K, &'a V)> { self.inner.next() }
1093 fn size_hint(&self) -> (uint, Option<uint>) { self.inner.size_hint() }
1096 impl<'a, K, V> DoubleEndedIterator for Iter<'a, K, V> {
1097 fn next_back(&mut self) -> Option<(&'a K, &'a V)> { self.inner.next_back() }
1100 impl<'a, K, V> ExactSizeIterator for Iter<'a, K, V> {}
1103 impl<'a, K, V> Iterator for IterMut<'a, K, V> {
1104 type Item = (&'a K, &'a mut V);
1106 fn next(&mut self) -> Option<(&'a K, &'a mut V)> { self.inner.next() }
1107 fn size_hint(&self) -> (uint, Option<uint>) { self.inner.size_hint() }
1110 impl<'a, K, V> DoubleEndedIterator for IterMut<'a, K, V> {
1111 fn next_back(&mut self) -> Option<(&'a K, &'a mut V)> { self.inner.next_back() }
1114 impl<'a, K, V> ExactSizeIterator for IterMut<'a, K, V> {}
1117 impl<K, V> Iterator for IntoIter<K, V> {
1120 fn next(&mut self) -> Option<(K, V)> { self.inner.next() }
1121 fn size_hint(&self) -> (uint, Option<uint>) { self.inner.size_hint() }
1124 impl<K, V> DoubleEndedIterator for IntoIter<K, V> {
1125 fn next_back(&mut self) -> Option<(K, V)> { self.inner.next_back() }
1128 impl<K, V> ExactSizeIterator for IntoIter<K, V> {}
1131 impl<'a, K, V> Iterator for Keys<'a, K, V> {
1134 fn next(&mut self) -> Option<(&'a K)> { self.inner.next() }
1135 fn size_hint(&self) -> (uint, Option<uint>) { self.inner.size_hint() }
1138 impl<'a, K, V> DoubleEndedIterator for Keys<'a, K, V> {
1139 fn next_back(&mut self) -> Option<(&'a K)> { self.inner.next_back() }
1142 impl<'a, K, V> ExactSizeIterator for Keys<'a, K, V> {}
1146 impl<'a, K, V> Iterator for Values<'a, K, V> {
1149 fn next(&mut self) -> Option<(&'a V)> { self.inner.next() }
1150 fn size_hint(&self) -> (uint, Option<uint>) { self.inner.size_hint() }
1153 impl<'a, K, V> DoubleEndedIterator for Values<'a, K, V> {
1154 fn next_back(&mut self) -> Option<(&'a V)> { self.inner.next_back() }
1157 impl<'a, K, V> ExactSizeIterator for Values<'a, K, V> {}
1160 impl<'a, K: Ord, V> VacantEntry<'a, K, V> {
1161 /// Sets the value of the entry with the VacantEntry's key,
1162 /// and returns a mutable reference to it.
1163 pub fn set(self, value: V) -> &'a mut V {
1164 self.stack.insert(self.key, value)
1168 impl<'a, K: Ord, V> OccupiedEntry<'a, K, V> {
1169 /// Gets a reference to the value in the entry.
1170 pub fn get(&self) -> &V {
1174 /// Gets a mutable reference to the value in the entry.
1175 pub fn get_mut(&mut self) -> &mut V {
1176 self.stack.peek_mut()
1179 /// Converts the entry into a mutable reference to its value.
1180 pub fn into_mut(self) -> &'a mut V {
1181 self.stack.into_top()
1184 /// Sets the value of the entry with the OccupiedEntry's key,
1185 /// and returns the entry's old value.
1186 pub fn set(&mut self, mut value: V) -> V {
1187 mem::swap(self.stack.peek_mut(), &mut value);
1191 /// Takes the value of the entry out of the map, and returns it.
1192 pub fn take(self) -> V {
1197 impl<K, V> BTreeMap<K, V> {
1198 /// Gets an iterator over the entries of the map.
1203 /// use std::collections::BTreeMap;
1205 /// let mut map = BTreeMap::new();
1206 /// map.insert(1u, "a");
1207 /// map.insert(2u, "b");
1208 /// map.insert(3u, "c");
1210 /// for (key, value) in map.iter() {
1211 /// println!("{}: {}", key, value);
1214 /// let (first_key, first_value) = map.iter().next().unwrap();
1215 /// assert_eq!((*first_key, *first_value), (1u, "a"));
1218 pub fn iter(&self) -> Iter<K, V> {
1219 let len = self.len();
1222 lca: Traverse::traverse(&self.root),
1223 left: RingBuf::new(),
1224 right: RingBuf::new(),
1230 /// Gets a mutable iterator over the entries of the map.
1235 /// use std::collections::BTreeMap;
1237 /// let mut map = BTreeMap::new();
1238 /// map.insert("a", 1u);
1239 /// map.insert("b", 2u);
1240 /// map.insert("c", 3u);
1242 /// // add 10 to the value if the key isn't "a"
1243 /// for (key, value) in map.iter_mut() {
1244 /// if key != &"a" {
1250 pub fn iter_mut(&mut self) -> IterMut<K, V> {
1251 let len = self.len();
1254 lca: Traverse::traverse(&mut self.root),
1255 left: RingBuf::new(),
1256 right: RingBuf::new(),
1262 /// Gets an owning iterator over the entries of the map.
1267 /// use std::collections::BTreeMap;
1269 /// let mut map = BTreeMap::new();
1270 /// map.insert(1u, "a");
1271 /// map.insert(2u, "b");
1272 /// map.insert(3u, "c");
1274 /// for (key, value) in map.into_iter() {
1275 /// println!("{}: {}", key, value);
1279 pub fn into_iter(self) -> IntoIter<K, V> {
1280 let len = self.len();
1283 lca: Traverse::traverse(self.root),
1284 left: RingBuf::new(),
1285 right: RingBuf::new(),
1291 /// Gets an iterator over the keys of the map.
1296 /// use std::collections::BTreeMap;
1298 /// let mut a = BTreeMap::new();
1299 /// a.insert(1u, "a");
1300 /// a.insert(2u, "b");
1302 /// let keys: Vec<uint> = a.keys().cloned().collect();
1303 /// assert_eq!(keys, vec![1u,2,]);
1306 pub fn keys<'a>(&'a self) -> Keys<'a, K, V> {
1307 fn first<A, B>((a, _): (A, B)) -> A { a }
1308 let first: fn((&'a K, &'a V)) -> &'a K = first; // coerce to fn pointer
1310 Keys { inner: self.iter().map(first) }
1313 /// Gets an iterator over the values of the map.
1318 /// use std::collections::BTreeMap;
1320 /// let mut a = BTreeMap::new();
1321 /// a.insert(1u, "a");
1322 /// a.insert(2u, "b");
1324 /// let values: Vec<&str> = a.values().cloned().collect();
1325 /// assert_eq!(values, vec!["a","b"]);
1328 pub fn values<'a>(&'a self) -> Values<'a, K, V> {
1329 fn second<A, B>((_, b): (A, B)) -> B { b }
1330 let second: fn((&'a K, &'a V)) -> &'a V = second; // coerce to fn pointer
1332 Values { inner: self.iter().map(second) }
1335 /// Return the number of elements in the map.
1340 /// use std::collections::BTreeMap;
1342 /// let mut a = BTreeMap::new();
1343 /// assert_eq!(a.len(), 0);
1344 /// a.insert(1u, "a");
1345 /// assert_eq!(a.len(), 1);
1348 pub fn len(&self) -> uint { self.length }
1350 /// Return true if the map contains no elements.
1355 /// use std::collections::BTreeMap;
1357 /// let mut a = BTreeMap::new();
1358 /// assert!(a.is_empty());
1359 /// a.insert(1u, "a");
1360 /// assert!(!a.is_empty());
1363 pub fn is_empty(&self) -> bool { self.len() == 0 }
1366 impl<K: Ord, V> BTreeMap<K, V> {
1367 /// Gets the given key's corresponding entry in the map for in-place manipulation.
1372 /// use std::collections::BTreeMap;
1373 /// use std::collections::btree_map::Entry;
1375 /// let mut count: BTreeMap<&str, uint> = BTreeMap::new();
1377 /// // count the number of occurrences of letters in the vec
1378 /// for x in vec!["a","b","a","c","a","b"].iter() {
1379 /// match count.entry(*x) {
1380 /// Entry::Vacant(view) => {
1383 /// Entry::Occupied(mut view) => {
1384 /// let v = view.get_mut();
1390 /// assert_eq!(count["a"], 3u);
1392 pub fn entry<'a>(&'a mut self, mut key: K) -> Entry<'a, K, V> {
1393 // same basic logic of `swap` and `pop`, blended together
1394 let mut stack = stack::PartialSearchStack::new(self);
1396 let result = stack.with(move |pusher, node| {
1397 return match Node::search(node, &key) {
1400 Finished(Occupied(OccupiedEntry {
1401 stack: pusher.seal(handle)
1405 match handle.force() {
1406 Leaf(leaf_handle) => {
1407 Finished(Vacant(VacantEntry {
1408 stack: pusher.seal(leaf_handle),
1412 Internal(internal_handle) => {
1414 pusher.push(internal_handle),
1423 Finished(finished) => return finished,
1424 Continue((new_stack, renewed_key)) => {
1441 use super::{BTreeMap, Occupied, Vacant};
1444 fn test_basic_large() {
1445 let mut map = BTreeMap::new();
1447 assert_eq!(map.len(), 0);
1449 for i in range(0, size) {
1450 assert_eq!(map.insert(i, 10*i), None);
1451 assert_eq!(map.len(), i + 1);
1454 for i in range(0, size) {
1455 assert_eq!(map.get(&i).unwrap(), &(i*10));
1458 for i in range(size, size*2) {
1459 assert_eq!(map.get(&i), None);
1462 for i in range(0, size) {
1463 assert_eq!(map.insert(i, 100*i), Some(10*i));
1464 assert_eq!(map.len(), size);
1467 for i in range(0, size) {
1468 assert_eq!(map.get(&i).unwrap(), &(i*100));
1471 for i in range(0, size/2) {
1472 assert_eq!(map.remove(&(i*2)), Some(i*200));
1473 assert_eq!(map.len(), size - i - 1);
1476 for i in range(0, size/2) {
1477 assert_eq!(map.get(&(2*i)), None);
1478 assert_eq!(map.get(&(2*i+1)).unwrap(), &(i*200 + 100));
1481 for i in range(0, size/2) {
1482 assert_eq!(map.remove(&(2*i)), None);
1483 assert_eq!(map.remove(&(2*i+1)), Some(i*200 + 100));
1484 assert_eq!(map.len(), size/2 - i - 1);
1489 fn test_basic_small() {
1490 let mut map = BTreeMap::new();
1491 assert_eq!(map.remove(&1), None);
1492 assert_eq!(map.get(&1), None);
1493 assert_eq!(map.insert(1u, 1u), None);
1494 assert_eq!(map.get(&1), Some(&1));
1495 assert_eq!(map.insert(1, 2), Some(1));
1496 assert_eq!(map.get(&1), Some(&2));
1497 assert_eq!(map.insert(2, 4), None);
1498 assert_eq!(map.get(&2), Some(&4));
1499 assert_eq!(map.remove(&1), Some(2));
1500 assert_eq!(map.remove(&2), Some(4));
1501 assert_eq!(map.remove(&1), None);
1509 let mut map: BTreeMap<uint, uint> = Vec::from_fn(size, |i| (i, i)).into_iter().collect();
1512 let mut iter = map.iter();
1513 for i in range(0, size) {
1514 assert_eq!(iter.size_hint(), (size - i, Some(size - i)));
1515 assert_eq!(iter.next().unwrap(), (&i, &i));
1517 assert_eq!(iter.size_hint(), (0, Some(0)));
1518 assert_eq!(iter.next(), None);
1522 let mut iter = map.iter_mut();
1523 for i in range(0, size) {
1524 assert_eq!(iter.size_hint(), (size - i, Some(size - i)));
1525 assert_eq!(iter.next().unwrap(), (&i, &mut (i + 0)));
1527 assert_eq!(iter.size_hint(), (0, Some(0)));
1528 assert_eq!(iter.next(), None);
1532 let mut iter = map.into_iter();
1533 for i in range(0, size) {
1534 assert_eq!(iter.size_hint(), (size - i, Some(size - i)));
1535 assert_eq!(iter.next().unwrap(), (i, i));
1537 assert_eq!(iter.size_hint(), (0, Some(0)));
1538 assert_eq!(iter.next(), None);
1544 fn test_iter_rev() {
1548 let mut map: BTreeMap<uint, uint> = Vec::from_fn(size, |i| (i, i)).into_iter().collect();
1551 let mut iter = map.iter().rev();
1552 for i in range(0, size) {
1553 assert_eq!(iter.size_hint(), (size - i, Some(size - i)));
1554 assert_eq!(iter.next().unwrap(), (&(size - i - 1), &(size - i - 1)));
1556 assert_eq!(iter.size_hint(), (0, Some(0)));
1557 assert_eq!(iter.next(), None);
1561 let mut iter = map.iter_mut().rev();
1562 for i in range(0, size) {
1563 assert_eq!(iter.size_hint(), (size - i, Some(size - i)));
1564 assert_eq!(iter.next().unwrap(), (&(size - i - 1), &mut(size - i - 1)));
1566 assert_eq!(iter.size_hint(), (0, Some(0)));
1567 assert_eq!(iter.next(), None);
1571 let mut iter = map.into_iter().rev();
1572 for i in range(0, size) {
1573 assert_eq!(iter.size_hint(), (size - i, Some(size - i)));
1574 assert_eq!(iter.next().unwrap(), (size - i - 1, size - i - 1));
1576 assert_eq!(iter.size_hint(), (0, Some(0)));
1577 assert_eq!(iter.next(), None);
1584 let xs = [(1i, 10i), (2, 20), (3, 30), (4, 40), (5, 50), (6, 60)];
1586 let mut map: BTreeMap<int, int> = xs.iter().map(|&x| x).collect();
1588 // Existing key (insert)
1589 match map.entry(1) {
1590 Vacant(_) => unreachable!(),
1591 Occupied(mut view) => {
1592 assert_eq!(view.get(), &10);
1593 assert_eq!(view.set(100), 10);
1596 assert_eq!(map.get(&1).unwrap(), &100);
1597 assert_eq!(map.len(), 6);
1600 // Existing key (update)
1601 match map.entry(2) {
1602 Vacant(_) => unreachable!(),
1603 Occupied(mut view) => {
1604 let v = view.get_mut();
1608 assert_eq!(map.get(&2).unwrap(), &200);
1609 assert_eq!(map.len(), 6);
1611 // Existing key (take)
1612 match map.entry(3) {
1613 Vacant(_) => unreachable!(),
1615 assert_eq!(view.take(), 30);
1618 assert_eq!(map.get(&3), None);
1619 assert_eq!(map.len(), 5);
1622 // Inexistent key (insert)
1623 match map.entry(10) {
1624 Occupied(_) => unreachable!(),
1626 assert_eq!(*view.set(1000), 1000);
1629 assert_eq!(map.get(&10).unwrap(), &1000);
1630 assert_eq!(map.len(), 6);
1642 use std::rand::{weak_rng, Rng};
1643 use test::{Bencher, black_box};
1645 use super::BTreeMap;
1646 use bench::{insert_rand_n, insert_seq_n, find_rand_n, find_seq_n};
1649 pub fn insert_rand_100(b: &mut Bencher) {
1650 let mut m : BTreeMap<uint,uint> = BTreeMap::new();
1651 insert_rand_n(100, &mut m, b,
1652 |m, i| { m.insert(i, 1); },
1653 |m, i| { m.remove(&i); });
1657 pub fn insert_rand_10_000(b: &mut Bencher) {
1658 let mut m : BTreeMap<uint,uint> = BTreeMap::new();
1659 insert_rand_n(10_000, &mut m, b,
1660 |m, i| { m.insert(i, 1); },
1661 |m, i| { m.remove(&i); });
1666 pub fn insert_seq_100(b: &mut Bencher) {
1667 let mut m : BTreeMap<uint,uint> = BTreeMap::new();
1668 insert_seq_n(100, &mut m, b,
1669 |m, i| { m.insert(i, 1); },
1670 |m, i| { m.remove(&i); });
1674 pub fn insert_seq_10_000(b: &mut Bencher) {
1675 let mut m : BTreeMap<uint,uint> = BTreeMap::new();
1676 insert_seq_n(10_000, &mut m, b,
1677 |m, i| { m.insert(i, 1); },
1678 |m, i| { m.remove(&i); });
1683 pub fn find_rand_100(b: &mut Bencher) {
1684 let mut m : BTreeMap<uint,uint> = BTreeMap::new();
1685 find_rand_n(100, &mut m, b,
1686 |m, i| { m.insert(i, 1); },
1687 |m, i| { m.get(&i); });
1691 pub fn find_rand_10_000(b: &mut Bencher) {
1692 let mut m : BTreeMap<uint,uint> = BTreeMap::new();
1693 find_rand_n(10_000, &mut m, b,
1694 |m, i| { m.insert(i, 1); },
1695 |m, i| { m.get(&i); });
1700 pub fn find_seq_100(b: &mut Bencher) {
1701 let mut m : BTreeMap<uint,uint> = BTreeMap::new();
1702 find_seq_n(100, &mut m, b,
1703 |m, i| { m.insert(i, 1); },
1704 |m, i| { m.get(&i); });
1708 pub fn find_seq_10_000(b: &mut Bencher) {
1709 let mut m : BTreeMap<uint,uint> = BTreeMap::new();
1710 find_seq_n(10_000, &mut m, b,
1711 |m, i| { m.insert(i, 1); },
1712 |m, i| { m.get(&i); });
1715 fn bench_iter(b: &mut Bencher, size: uint) {
1716 let mut map = BTreeMap::<uint, uint>::new();
1717 let mut rng = weak_rng();
1719 for _ in range(0, size) {
1720 map.insert(rng.gen(), rng.gen());
1724 for entry in map.iter() {
1731 pub fn iter_20(b: &mut Bencher) {
1736 pub fn iter_1000(b: &mut Bencher) {
1737 bench_iter(b, 1000);
1741 pub fn iter_100000(b: &mut Bencher) {
1742 bench_iter(b, 100000);