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::{Hash, Hasher};
27 use core::iter::{Map, FromIterator};
28 use core::ops::{Index, IndexMut};
29 use core::{iter, fmt, mem};
30 use Bound::{self, Included, Excluded, Unbounded};
32 use ring_buf::RingBuf;
34 use self::Continuation::{Continue, Finished};
36 use super::node::ForceResult::{Leaf, Internal};
37 use super::node::TraversalItem::{self, Elem, Edge};
38 use super::node::{Traversal, MutTraversal, MoveTraversal};
39 use super::node::{self, Node, Found, GoDown};
41 /// A map based on a B-Tree.
43 /// B-Trees represent a fundamental compromise between cache-efficiency and actually minimizing
44 /// the amount of work performed in a search. In theory, a binary search tree (BST) is the optimal
45 /// choice for a sorted map, as a perfectly balanced BST performs the theoretical minimum amount of
46 /// comparisons necessary to find an element (log<sub>2</sub>n). However, in practice the way this
47 /// is done is *very* inefficient for modern computer architectures. In particular, every element
48 /// is stored in its own individually heap-allocated node. This means that every single insertion
49 /// triggers a heap-allocation, and every single comparison should be a cache-miss. Since these
50 /// are both notably expensive things to do in practice, we are forced to at very least reconsider
53 /// A B-Tree instead makes each node contain B-1 to 2B-1 elements in a contiguous array. By doing
54 /// this, we reduce the number of allocations by a factor of B, and improve cache efficiency in
55 /// searches. However, this does mean that searches will have to do *more* comparisons on average.
56 /// The precise number of comparisons depends on the node search strategy used. For optimal cache
57 /// efficiency, one could search the nodes linearly. For optimal comparisons, one could search
58 /// the node using binary search. As a compromise, one could also perform a linear search
59 /// that initially only checks every i<sup>th</sup> element for some choice of i.
61 /// Currently, our implementation simply performs naive linear search. This provides excellent
62 /// performance on *small* nodes of elements which are cheap to compare. However in the future we
63 /// would like to further explore choosing the optimal search strategy based on the choice of B,
64 /// and possibly other factors. Using linear search, searching for a random element is expected
65 /// to take O(B log<sub>B</sub>n) comparisons, which is generally worse than a BST. In practice,
66 /// however, performance is excellent. `BTreeMap` is able to readily outperform `TreeMap` under
67 /// many workloads, and is competitive where it doesn't. BTreeMap also generally *scales* better
68 /// than TreeMap, making it more appropriate for large datasets.
70 /// However, `TreeMap` may still be more appropriate to use in many contexts. If elements are very
71 /// large or expensive to compare, `TreeMap` may be more appropriate. It won't allocate any
72 /// more space than is needed, and will perform the minimal number of comparisons necessary.
73 /// `TreeMap` also provides much better performance stability guarantees. Generally, very few
74 /// changes need to be made to update a BST, and two updates are expected to take about the same
75 /// amount of time on roughly equal sized BSTs. However a B-Tree's performance is much more
76 /// amortized. If a node is overfull, it must be split into two nodes. If a node is underfull, it
77 /// may be merged with another. Both of these operations are relatively expensive to perform, and
78 /// it's possible to force one to occur at every single level of the tree in a single insertion or
79 /// deletion. In fact, a malicious or otherwise unlucky sequence of insertions and deletions can
80 /// force this degenerate behaviour to occur on every operation. While the total amount of work
81 /// done on each operation isn't *catastrophic*, and *is* still bounded by O(B log<sub>B</sub>n),
82 /// it is certainly much slower when it does.
85 pub struct BTreeMap<K, V> {
92 /// An abstract base over-which all other BTree iterators are built.
94 traversals: RingBuf<T>,
98 /// An iterator over a BTreeMap's entries.
100 pub struct Iter<'a, K: 'a, V: 'a> {
101 inner: AbsIter<Traversal<'a, K, V>>
104 /// A mutable iterator over a BTreeMap's entries.
106 pub struct IterMut<'a, K: 'a, V: 'a> {
107 inner: AbsIter<MutTraversal<'a, K, V>>
110 /// An owning iterator over a BTreeMap's entries.
112 pub struct IntoIter<K, V> {
113 inner: AbsIter<MoveTraversal<K, V>>
116 /// An iterator over a BTreeMap's keys.
118 pub struct Keys<'a, K: 'a, V: 'a> {
119 inner: Map<(&'a K, &'a V), &'a K, Iter<'a, K, V>, fn((&'a K, &'a V)) -> &'a K>
122 /// An iterator over a BTreeMap's values.
124 pub struct Values<'a, K: 'a, V: 'a> {
125 inner: Map<(&'a K, &'a V), &'a V, Iter<'a, K, V>, fn((&'a K, &'a V)) -> &'a V>
128 /// An iterator over a sub-range of BTreeMap's entries.
129 pub struct Range<'a, K: 'a, V: 'a> {
130 inner: AbsIter<Traversal<'a, K, V>>
133 /// A mutable iterator over a sub-range of BTreeMap's entries.
134 pub struct RangeMut<'a, K: 'a, V: 'a> {
135 inner: AbsIter<MutTraversal<'a, K, V>>
138 /// A view into a single entry in a map, which may either be vacant or occupied.
139 #[unstable = "precise API still under development"]
140 pub enum Entry<'a, K:'a, V:'a> {
142 Vacant(VacantEntry<'a, K, V>),
143 /// An occupied Entry
144 Occupied(OccupiedEntry<'a, K, V>),
148 #[unstable = "precise API still under development"]
149 pub struct VacantEntry<'a, K:'a, V:'a> {
151 stack: stack::SearchStack<'a, K, V, node::handle::Edge, node::handle::Leaf>,
154 /// An occupied Entry.
155 #[unstable = "precise API still under development"]
156 pub struct OccupiedEntry<'a, K:'a, V:'a> {
157 stack: stack::SearchStack<'a, K, V, node::handle::KV, node::handle::LeafOrInternal>,
160 impl<K: Ord, V> BTreeMap<K, V> {
161 /// Makes a new empty BTreeMap with a reasonable choice for B.
163 pub fn new() -> BTreeMap<K, V> {
164 //FIXME(Gankro): Tune this as a function of size_of<K/V>?
168 /// Makes a new empty BTreeMap with the given B.
170 /// B cannot be less than 2.
171 pub fn with_b(b: uint) -> BTreeMap<K, V> {
172 assert!(b > 1, "B must be greater than 1");
176 root: Node::make_leaf_root(b),
181 /// Clears the map, removing all values.
186 /// use std::collections::BTreeMap;
188 /// let mut a = BTreeMap::new();
189 /// a.insert(1u, "a");
191 /// assert!(a.is_empty());
194 pub fn clear(&mut self) {
196 // avoid recursive destructors by manually traversing the tree
197 for _ in mem::replace(self, BTreeMap::with_b(b)).into_iter() {};
200 // Searching in a B-Tree is pretty straightforward.
202 // Start at the root. Try to find the key in the current node. If we find it, return it.
203 // If it's not in there, follow the edge *before* the smallest key larger than
204 // the search key. If no such key exists (they're *all* smaller), then just take the last
205 // edge in the node. If we're in a leaf and we don't find our key, then it's not
208 /// Returns a reference to the value corresponding to the key.
210 /// The key may be any borrowed form of the map's key type, but the ordering
211 /// on the borrowed form *must* match the ordering on the key type.
216 /// use std::collections::BTreeMap;
218 /// let mut map = BTreeMap::new();
219 /// map.insert(1u, "a");
220 /// assert_eq!(map.get(&1), Some(&"a"));
221 /// assert_eq!(map.get(&2), None);
224 pub fn get<Q: ?Sized>(&self, key: &Q) -> Option<&V> where Q: BorrowFrom<K> + Ord {
225 let mut cur_node = &self.root;
227 match Node::search(cur_node, key) {
228 Found(handle) => return Some(handle.into_kv().1),
229 GoDown(handle) => match handle.force() {
230 Leaf(_) => return None,
231 Internal(internal_handle) => {
232 cur_node = internal_handle.into_edge();
240 /// Returns true if the map contains a value for the specified key.
242 /// The key may be any borrowed form of the map's key type, but the ordering
243 /// on the borrowed form *must* match the ordering on the key type.
248 /// use std::collections::BTreeMap;
250 /// let mut map = BTreeMap::new();
251 /// map.insert(1u, "a");
252 /// assert_eq!(map.contains_key(&1), true);
253 /// assert_eq!(map.contains_key(&2), false);
256 pub fn contains_key<Q: ?Sized>(&self, key: &Q) -> bool where Q: BorrowFrom<K> + Ord {
257 self.get(key).is_some()
260 /// Returns a mutable reference to the value corresponding to the key.
262 /// The key may be any borrowed form of the map's key type, but the ordering
263 /// on the borrowed form *must* match the ordering on the key type.
268 /// use std::collections::BTreeMap;
270 /// let mut map = BTreeMap::new();
271 /// map.insert(1u, "a");
272 /// match map.get_mut(&1) {
273 /// Some(x) => *x = "b",
276 /// assert_eq!(map[1], "b");
278 // See `get` for implementation notes, this is basically a copy-paste with mut's added
280 pub fn get_mut<Q: ?Sized>(&mut self, key: &Q) -> Option<&mut V> where Q: BorrowFrom<K> + Ord {
281 // temp_node is a Borrowck hack for having a mutable value outlive a loop iteration
282 let mut temp_node = &mut self.root;
284 let cur_node = temp_node;
285 match Node::search(cur_node, key) {
286 Found(handle) => return Some(handle.into_kv_mut().1),
287 GoDown(handle) => match handle.force() {
288 Leaf(_) => return None,
289 Internal(internal_handle) => {
290 temp_node = internal_handle.into_edge_mut();
298 // Insertion in a B-Tree is a bit complicated.
300 // First we do the same kind of search described in `find`. But we need to maintain a stack of
301 // all the nodes/edges in our search path. If we find a match for the key we're trying to
302 // insert, just swap the vals and return the old ones. However, when we bottom out in a leaf,
303 // we attempt to insert our key-value pair at the same location we would want to follow another
306 // If the node has room, then this is done in the obvious way by shifting elements. However,
307 // if the node itself is full, we split node into two, and give its median key-value
308 // pair to its parent to insert the new node with. Of course, the parent may also be
309 // full, and insertion can propagate until we reach the root. If we reach the root, and
310 // it is *also* full, then we split the root and place the two nodes under a newly made root.
312 // Note that we subtly deviate from Open Data Structures in our implementation of split.
313 // ODS describes inserting into the node *regardless* of its capacity, and then
314 // splitting *afterwards* if it happens to be overfull. However, this is inefficient.
315 // Instead, we split beforehand, and then insert the key-value pair into the appropriate
316 // result node. This has two consequences:
318 // 1) While ODS produces a left node of size B-1, and a right node of size B,
319 // we may potentially reverse this. However, this shouldn't effect the analysis.
321 // 2) While ODS may potentially return the pair we *just* inserted after
322 // the split, we will never do this. Again, this shouldn't effect the analysis.
324 /// Inserts a key-value pair from the map. If the key already had a value
325 /// present in the map, that value is returned. Otherwise, `None` is returned.
330 /// use std::collections::BTreeMap;
332 /// let mut map = BTreeMap::new();
333 /// assert_eq!(map.insert(37u, "a"), None);
334 /// assert_eq!(map.is_empty(), false);
336 /// map.insert(37, "b");
337 /// assert_eq!(map.insert(37, "c"), Some("b"));
338 /// assert_eq!(map[37], "c");
341 pub fn insert(&mut self, mut key: K, mut value: V) -> Option<V> {
342 // This is a stack of rawptrs to nodes paired with indices, respectively
343 // representing the nodes and edges of our search path. We have to store rawptrs
344 // because as far as Rust is concerned, we can mutate aliased data with such a
345 // stack. It is of course correct, but what it doesn't know is that we will only
346 // be popping and using these ptrs one at a time in child-to-parent order. The alternative
347 // to doing this is to take the Nodes from their parents. This actually makes
348 // borrowck *really* happy and everything is pretty smooth. However, this creates
349 // *tons* of pointless writes, and requires us to always walk all the way back to
350 // the root after an insertion, even if we only needed to change a leaf. Therefore,
351 // we accept this potential unsafety and complexity in the name of performance.
353 // Regardless, the actual dangerous logic is completely abstracted away from BTreeMap
354 // by the stack module. All it can do is immutably read nodes, and ask the search stack
355 // to proceed down some edge by index. This makes the search logic we'll be reusing in a
356 // few different methods much neater, and of course drastically improves safety.
357 let mut stack = stack::PartialSearchStack::new(self);
360 let result = stack.with(move |pusher, node| {
361 // Same basic logic as found in `find`, but with PartialSearchStack mediating the
362 // actual nodes for us
363 return match Node::search(node, &key) {
364 Found(mut handle) => {
365 // Perfect match, swap the values and return the old one
366 mem::swap(handle.val_mut(), &mut value);
367 Finished(Some(value))
370 // We need to keep searching, try to get the search stack
371 // to go down further
372 match handle.force() {
373 Leaf(leaf_handle) => {
374 // We've reached a leaf, perform the insertion here
375 pusher.seal(leaf_handle).insert(key, value);
378 Internal(internal_handle) => {
379 // We've found the subtree to insert this key/value pair in,
381 Continue((pusher.push(internal_handle), key, value))
388 Finished(ret) => { return ret; },
389 Continue((new_stack, renewed_key, renewed_val)) => {
398 // Deletion is the most complicated operation for a B-Tree.
400 // First we do the same kind of search described in
401 // `find`. But we need to maintain a stack of all the nodes/edges in our search path.
402 // If we don't find the key, then we just return `None` and do nothing. If we do find the
403 // key, we perform two operations: remove the item, and then possibly handle underflow.
405 // # removing the item
406 // If the node is a leaf, we just remove the item, and shift
407 // any items after it back to fill the hole.
409 // If the node is an internal node, we *swap* the item with the smallest item in
410 // in its right subtree (which must reside in a leaf), and then revert to the leaf
413 // # handling underflow
414 // After removing an item, there may be too few items in the node. We want nodes
415 // to be mostly full for efficiency, although we make an exception for the root, which
416 // may have as few as one item. If this is the case, we may first try to steal
417 // an item from our left or right neighbour.
419 // To steal from the left (right) neighbour,
420 // we take the largest (smallest) item and child from it. We then swap the taken item
421 // with the item in their mutual parent that separates them, and then insert the
422 // parent's item and the taken child into the first (last) index of the underflowed node.
424 // However, stealing has the possibility of underflowing our neighbour. If this is the
425 // case, we instead *merge* with our neighbour. This of course reduces the number of
426 // children in the parent. Therefore, we also steal the item that separates the now
427 // merged nodes, and insert it into the merged node.
429 // Merging may cause the parent to underflow. If this is the case, then we must repeat
430 // the underflow handling process on the parent. If merging merges the last two children
431 // of the root, then we replace the root with the merged node.
433 /// Removes a key from the map, returning the value at the key if the key
434 /// was previously in the map.
436 /// The key may be any borrowed form of the map's key type, but the ordering
437 /// on the borrowed form *must* match the ordering on the key type.
442 /// use std::collections::BTreeMap;
444 /// let mut map = BTreeMap::new();
445 /// map.insert(1u, "a");
446 /// assert_eq!(map.remove(&1), Some("a"));
447 /// assert_eq!(map.remove(&1), None);
450 pub fn remove<Q: ?Sized>(&mut self, key: &Q) -> Option<V> where Q: BorrowFrom<K> + Ord {
451 // See `swap` for a more thorough description of the stuff going on in here
452 let mut stack = stack::PartialSearchStack::new(self);
454 let result = stack.with(move |pusher, node| {
455 return match Node::search(node, key) {
457 // Perfect match. Terminate the stack here, and remove the entry
458 Finished(Some(pusher.seal(handle).remove()))
461 // We need to keep searching, try to go down the next edge
462 match handle.force() {
463 // We're at a leaf; the key isn't in here
464 Leaf(_) => Finished(None),
465 Internal(internal_handle) => Continue(pusher.push(internal_handle))
471 Finished(ret) => return ret,
472 Continue(new_stack) => stack = new_stack
478 /// A helper enum useful for deciding whether to continue a loop since we can't
479 /// return from a closure
480 enum Continuation<A, B> {
485 /// The stack module provides a safe interface for constructing and manipulating a stack of ptrs
486 /// to nodes. By using this module much better safety guarantees can be made, and more search
487 /// boilerplate gets cut out.
489 use core::prelude::*;
492 use core::ops::{Deref, DerefMut};
494 use super::super::node::{self, Node, Fit, Split, Internal, Leaf};
495 use super::super::node::handle;
498 /// A generic mutable reference, identical to `&mut` except for the fact that its lifetime
499 /// parameter is invariant. This means that wherever an `IdRef` is expected, only an `IdRef`
500 /// with the exact requested lifetime can be used. This is in contrast to normal references,
501 /// where `&'static` can be used in any function expecting any lifetime reference.
502 pub struct IdRef<'id, T: 'id> {
504 marker: marker::InvariantLifetime<'id>
507 impl<'id, T> Deref for IdRef<'id, T> {
510 fn deref(&self) -> &T {
515 impl<'id, T> DerefMut for IdRef<'id, T> {
516 fn deref_mut(&mut self) -> &mut T {
521 type StackItem<K, V> = node::Handle<*mut Node<K, V>, handle::Edge, handle::Internal>;
522 type Stack<K, V> = Vec<StackItem<K, V>>;
524 /// A `PartialSearchStack` handles the construction of a search stack.
525 pub struct PartialSearchStack<'a, K:'a, V:'a> {
526 map: &'a mut BTreeMap<K, V>,
528 next: *mut Node<K, V>,
531 /// A `SearchStack` represents a full path to an element or an edge of interest. It provides
532 /// methods depending on the type of what the path points to for removing an element, inserting
533 /// a new element, and manipulating to element at the top of the stack.
534 pub struct SearchStack<'a, K:'a, V:'a, Type, NodeType> {
535 map: &'a mut BTreeMap<K, V>,
537 top: node::Handle<*mut Node<K, V>, Type, NodeType>,
540 /// A `PartialSearchStack` that doesn't hold a a reference to the next node, and is just
541 /// just waiting for a `Handle` to that next node to be pushed. See `PartialSearchStack::with`
542 /// for more details.
543 pub struct Pusher<'id, 'a, K:'a, V:'a> {
544 map: &'a mut BTreeMap<K, V>,
546 marker: marker::InvariantLifetime<'id>
549 impl<'a, K, V> PartialSearchStack<'a, K, V> {
550 /// Creates a new PartialSearchStack from a BTreeMap by initializing the stack with the
551 /// root of the tree.
552 pub fn new(map: &'a mut BTreeMap<K, V>) -> PartialSearchStack<'a, K, V> {
553 let depth = map.depth;
556 next: &mut map.root as *mut _,
558 stack: Vec::with_capacity(depth),
562 /// Breaks up the stack into a `Pusher` and the next `Node`, allowing the given closure
563 /// to interact with, search, and finally push the `Node` onto the stack. The passed in
564 /// closure must be polymorphic on the `'id` lifetime parameter, as this statically
565 /// ensures that only `Handle`s from the correct `Node` can be pushed.
567 /// The reason this works is that the `Pusher` has an `'id` parameter, and will only accept
568 /// handles with the same `'id`. The closure could only get references with that lifetime
569 /// through its arguments or through some other `IdRef` that it has lying around. However,
570 /// no other `IdRef` could possibly work - because the `'id` is held in an invariant
571 /// parameter, it would need to have precisely the correct lifetime, which would mean that
572 /// at least one of the calls to `with` wouldn't be properly polymorphic, wanting a
573 /// specific lifetime instead of the one that `with` chooses to give it.
575 /// See also Haskell's `ST` monad, which uses a similar trick.
576 pub fn with<T, F: for<'id> FnOnce(Pusher<'id, 'a, K, V>,
577 IdRef<'id, Node<K, V>>) -> T>(self, closure: F) -> T {
578 let pusher = Pusher {
581 marker: marker::InvariantLifetime
584 inner: unsafe { &mut *self.next },
585 marker: marker::InvariantLifetime
588 closure(pusher, node)
592 impl<'id, 'a, K, V> Pusher<'id, 'a, K, V> {
593 /// Pushes the requested child of the stack's current top on top of the stack. If the child
594 /// exists, then a new PartialSearchStack is yielded. Otherwise, a VacantSearchStack is
596 pub fn push(mut self, mut edge: node::Handle<IdRef<'id, Node<K, V>>,
599 -> PartialSearchStack<'a, K, V> {
600 self.stack.push(edge.as_raw());
604 next: edge.edge_mut() as *mut _,
608 /// Converts the PartialSearchStack into a SearchStack.
609 pub fn seal<Type, NodeType>
610 (self, mut handle: node::Handle<IdRef<'id, Node<K, V>>, Type, NodeType>)
611 -> SearchStack<'a, K, V, Type, NodeType> {
615 top: handle.as_raw(),
620 impl<'a, K, V, NodeType> SearchStack<'a, K, V, handle::KV, NodeType> {
621 /// Gets a reference to the value the stack points to.
622 pub fn peek(&self) -> &V {
623 unsafe { self.top.from_raw().into_kv().1 }
626 /// Gets a mutable reference to the value the stack points to.
627 pub fn peek_mut(&mut self) -> &mut V {
628 unsafe { self.top.from_raw_mut().into_kv_mut().1 }
631 /// Converts the stack into a mutable reference to the value it points to, with a lifetime
632 /// tied to the original tree.
633 pub fn into_top(mut self) -> &'a mut V {
635 mem::copy_mut_lifetime(
637 self.top.from_raw_mut().val_mut()
643 impl<'a, K, V> SearchStack<'a, K, V, handle::KV, handle::Leaf> {
644 /// Removes the key and value in the top element of the stack, then handles underflows as
645 /// described in BTree's pop function.
646 fn remove_leaf(mut self) -> V {
647 self.map.length -= 1;
649 // Remove the key-value pair from the leaf that this search stack points to.
650 // Then, note if the leaf is underfull, and promptly forget the leaf and its ptr
651 // to avoid ownership issues.
652 let (value, mut underflow) = unsafe {
653 let (_, value) = self.top.from_raw_mut().remove_as_leaf();
654 let underflow = self.top.from_raw().node().is_underfull();
659 match self.stack.pop() {
661 // We've reached the root, so no matter what, we're done. We manually
662 // access the root via the tree itself to avoid creating any dangling
664 if self.map.root.len() == 0 && !self.map.root.is_leaf() {
665 // We've emptied out the root, so make its only child the new root.
666 // If it's a leaf, we just let it become empty.
668 self.map.root.hoist_lone_child();
672 Some(mut handle) => {
674 // Underflow! Handle it!
676 handle.from_raw_mut().handle_underflow();
677 underflow = handle.from_raw().node().is_underfull();
689 impl<'a, K, V> SearchStack<'a, K, V, handle::KV, handle::LeafOrInternal> {
690 /// Removes the key and value in the top element of the stack, then handles underflows as
691 /// described in BTree's pop function.
692 pub fn remove(self) -> V {
693 // Ensure that the search stack goes to a leaf. This is necessary to perform deletion
694 // in a BTree. Note that this may put the tree in an inconsistent state (further
695 // described in into_leaf's comments), but this is immediately fixed by the
696 // removing the value we want to remove
697 self.into_leaf().remove_leaf()
700 /// Subroutine for removal. Takes a search stack for a key that might terminate at an
701 /// internal node, and mutates the tree and search stack to *make* it a search stack
702 /// for that same key that *does* terminates at a leaf. If the mutation occurs, then this
703 /// leaves the tree in an inconsistent state that must be repaired by the caller by
704 /// removing the entry in question. Specifically the key-value pair and its successor will
706 fn into_leaf(mut self) -> SearchStack<'a, K, V, handle::KV, handle::Leaf> {
708 let mut top_raw = self.top;
709 let mut top = top_raw.from_raw_mut();
711 let key_ptr = top.key_mut() as *mut _;
712 let val_ptr = top.val_mut() as *mut _;
714 // Try to go into the right subtree of the found key to find its successor
716 Leaf(mut leaf_handle) => {
717 // We're a proper leaf stack, nothing to do
721 top: leaf_handle.as_raw()
724 Internal(mut internal_handle) => {
725 let mut right_handle = internal_handle.right_edge();
727 //We're not a proper leaf stack, let's get to work.
728 self.stack.push(right_handle.as_raw());
730 let mut temp_node = right_handle.edge_mut();
732 // Walk into the smallest subtree of this node
733 let node = temp_node;
735 match node.kv_handle(0).force() {
736 Leaf(mut handle) => {
737 // This node is a leaf, do the swap and return
738 mem::swap(handle.key_mut(), &mut *key_ptr);
739 mem::swap(handle.val_mut(), &mut *val_ptr);
746 Internal(kv_handle) => {
747 // This node is internal, go deeper
748 let mut handle = kv_handle.into_left_edge();
749 self.stack.push(handle.as_raw());
750 temp_node = handle.into_edge_mut();
760 impl<'a, K, V> SearchStack<'a, K, V, handle::Edge, handle::Leaf> {
761 /// Inserts the key and value into the top element in the stack, and if that node has to
762 /// split recursively inserts the split contents into the next element stack until
765 /// Assumes that the stack represents a search path from the root to a leaf.
767 /// An &mut V is returned to the inserted value, for callers that want a reference to this.
768 pub fn insert(mut self, key: K, val: V) -> &'a mut V {
770 self.map.length += 1;
772 // Insert the key and value into the leaf at the top of the stack
773 let (mut insertion, inserted_ptr) = self.top.from_raw_mut()
774 .insert_as_leaf(key, val);
779 // The last insertion went off without a hitch, no splits! We can stop
781 return &mut *inserted_ptr;
783 Split(key, val, right) => match self.stack.pop() {
784 // The last insertion triggered a split, so get the next element on the
785 // stack to recursively insert the split node into.
787 // The stack was empty; we've split the root, and need to make a
788 // a new one. This is done in-place because we can't move the
789 // root out of a reference to the tree.
790 Node::make_internal_root(&mut self.map.root, self.map.b,
794 return &mut *inserted_ptr;
796 Some(mut handle) => {
797 // The stack wasn't empty, do the insertion and recurse
798 insertion = handle.from_raw_mut()
799 .insert_as_internal(key, val, right);
811 impl<K: Ord, V> FromIterator<(K, V)> for BTreeMap<K, V> {
812 fn from_iter<T: Iterator<Item=(K, V)>>(iter: T) -> BTreeMap<K, V> {
813 let mut map = BTreeMap::new();
820 impl<K: Ord, V> Extend<(K, V)> for BTreeMap<K, V> {
822 fn extend<T: Iterator<Item=(K, V)>>(&mut self, mut iter: T) {
830 impl<S: Hasher, K: Hash<S>, V: Hash<S>> Hash<S> for BTreeMap<K, V> {
831 fn hash(&self, state: &mut S) {
832 for elt in self.iter() {
839 impl<K: Ord, V> Default for BTreeMap<K, V> {
841 fn default() -> BTreeMap<K, V> {
847 impl<K: PartialEq, V: PartialEq> PartialEq for BTreeMap<K, V> {
848 fn eq(&self, other: &BTreeMap<K, V>) -> bool {
849 self.len() == other.len() &&
850 self.iter().zip(other.iter()).all(|(a, b)| a == b)
855 impl<K: Eq, V: Eq> Eq for BTreeMap<K, V> {}
858 impl<K: PartialOrd, V: PartialOrd> PartialOrd for BTreeMap<K, V> {
860 fn partial_cmp(&self, other: &BTreeMap<K, V>) -> Option<Ordering> {
861 iter::order::partial_cmp(self.iter(), other.iter())
866 impl<K: Ord, V: Ord> Ord for BTreeMap<K, V> {
868 fn cmp(&self, other: &BTreeMap<K, V>) -> Ordering {
869 iter::order::cmp(self.iter(), other.iter())
874 impl<K: Debug, V: Debug> Debug for BTreeMap<K, V> {
875 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
876 try!(write!(f, "BTreeMap {{"));
878 for (i, (k, v)) in self.iter().enumerate() {
879 if i != 0 { try!(write!(f, ", ")); }
880 try!(write!(f, "{:?}: {:?}", *k, *v));
888 impl<K: Ord, Q: ?Sized, V> Index<Q> for BTreeMap<K, V>
889 where Q: BorrowFrom<K> + Ord
893 fn index(&self, key: &Q) -> &V {
894 self.get(key).expect("no entry found for key")
899 impl<K: Ord, Q: ?Sized, V> IndexMut<Q> for BTreeMap<K, V>
900 where Q: BorrowFrom<K> + Ord
904 fn index_mut(&mut self, key: &Q) -> &mut V {
905 self.get_mut(key).expect("no entry found for key")
909 /// Genericises over how to get the correct type of iterator from the correct type
910 /// of Node ownership.
912 fn traverse(node: N) -> Self;
915 impl<'a, K, V> Traverse<&'a Node<K, V>> for Traversal<'a, K, V> {
916 fn traverse(node: &'a Node<K, V>) -> Traversal<'a, K, V> {
921 impl<'a, K, V> Traverse<&'a mut Node<K, V>> for MutTraversal<'a, K, V> {
922 fn traverse(node: &'a mut Node<K, V>) -> MutTraversal<'a, K, V> {
927 impl<K, V> Traverse<Node<K, V>> for MoveTraversal<K, V> {
928 fn traverse(node: Node<K, V>) -> MoveTraversal<K, V> {
933 /// Represents an operation to perform inside the following iterator methods.
934 /// This is necessary to use in `next` because we want to modify `self.traversals` inside
935 /// a match that borrows it. Similarly in `next_back`. Instead, we use this enum to note
936 /// what we want to do, and do it after the match.
941 impl<K, V, E, T> Iterator for AbsIter<T> where
942 T: DoubleEndedIterator<Item=TraversalItem<K, V, E>> + Traverse<E>,
946 // Our iterator represents a queue of all ancestors of elements we have
947 // yet to yield, from smallest to largest. Note that the design of these
948 // iterators permits an *arbitrary* initial pair of min and max, making
949 // these arbitrary sub-range iterators.
950 fn next(&mut self) -> Option<(K, V)> {
952 // We want the smallest element, so try to get the back of the queue
953 let op = match self.traversals.back_mut() {
955 // The queue wasn't empty, so continue along the node in its head
956 Some(iter) => match iter.next() {
957 // The head is empty, so Pop it off and continue the process
959 // The head yielded an edge, so make that the new head
960 Some(Edge(next)) => Push(Traverse::traverse(next)),
961 // The head yielded an entry, so yield that
969 // Handle any operation as necessary, without a conflicting borrow of the queue
971 Push(item) => { self.traversals.push_back(item); },
972 Pop => { self.traversals.pop_back(); },
977 fn size_hint(&self) -> (uint, Option<uint>) {
978 (self.size, Some(self.size))
982 impl<K, V, E, T> DoubleEndedIterator for AbsIter<T> where
983 T: DoubleEndedIterator<Item=TraversalItem<K, V, E>> + Traverse<E>,
985 // next_back is totally symmetric to next
987 fn next_back(&mut self) -> Option<(K, V)> {
989 let op = match self.traversals.front_mut() {
991 Some(iter) => match iter.next_back() {
993 Some(Edge(next)) => Push(Traverse::traverse(next)),
1002 Push(item) => { self.traversals.push_front(item); },
1003 Pop => { self.traversals.pop_front(); }
1010 impl<'a, K, V> Iterator for Iter<'a, K, V> {
1011 type Item = (&'a K, &'a V);
1013 fn next(&mut self) -> Option<(&'a K, &'a V)> { self.inner.next() }
1014 fn size_hint(&self) -> (uint, Option<uint>) { self.inner.size_hint() }
1017 impl<'a, K, V> DoubleEndedIterator for Iter<'a, K, V> {
1018 fn next_back(&mut self) -> Option<(&'a K, &'a V)> { self.inner.next_back() }
1021 impl<'a, K, V> ExactSizeIterator for Iter<'a, K, V> {}
1024 impl<'a, K, V> Iterator for IterMut<'a, K, V> {
1025 type Item = (&'a K, &'a mut V);
1027 fn next(&mut self) -> Option<(&'a K, &'a mut V)> { self.inner.next() }
1028 fn size_hint(&self) -> (uint, Option<uint>) { self.inner.size_hint() }
1031 impl<'a, K, V> DoubleEndedIterator for IterMut<'a, K, V> {
1032 fn next_back(&mut self) -> Option<(&'a K, &'a mut V)> { self.inner.next_back() }
1035 impl<'a, K, V> ExactSizeIterator for IterMut<'a, K, V> {}
1038 impl<K, V> Iterator for IntoIter<K, V> {
1041 fn next(&mut self) -> Option<(K, V)> { self.inner.next() }
1042 fn size_hint(&self) -> (uint, Option<uint>) { self.inner.size_hint() }
1045 impl<K, V> DoubleEndedIterator for IntoIter<K, V> {
1046 fn next_back(&mut self) -> Option<(K, V)> { self.inner.next_back() }
1049 impl<K, V> ExactSizeIterator for IntoIter<K, V> {}
1052 impl<'a, K, V> Iterator for Keys<'a, K, V> {
1055 fn next(&mut self) -> Option<(&'a K)> { self.inner.next() }
1056 fn size_hint(&self) -> (uint, Option<uint>) { self.inner.size_hint() }
1059 impl<'a, K, V> DoubleEndedIterator for Keys<'a, K, V> {
1060 fn next_back(&mut self) -> Option<(&'a K)> { self.inner.next_back() }
1063 impl<'a, K, V> ExactSizeIterator for Keys<'a, K, V> {}
1067 impl<'a, K, V> Iterator for Values<'a, K, V> {
1070 fn next(&mut self) -> Option<(&'a V)> { self.inner.next() }
1071 fn size_hint(&self) -> (uint, Option<uint>) { self.inner.size_hint() }
1074 impl<'a, K, V> DoubleEndedIterator for Values<'a, K, V> {
1075 fn next_back(&mut self) -> Option<(&'a V)> { self.inner.next_back() }
1078 impl<'a, K, V> ExactSizeIterator for Values<'a, K, V> {}
1080 impl<'a, K, V> Iterator for Range<'a, K, V> {
1081 type Item = (&'a K, &'a V);
1083 fn next(&mut self) -> Option<(&'a K, &'a V)> { self.inner.next() }
1085 impl<'a, K, V> DoubleEndedIterator for Range<'a, K, V> {
1086 fn next_back(&mut self) -> Option<(&'a K, &'a V)> { self.inner.next_back() }
1089 impl<'a, K, V> Iterator for RangeMut<'a, K, V> {
1090 type Item = (&'a K, &'a mut V);
1092 fn next(&mut self) -> Option<(&'a K, &'a mut V)> { self.inner.next() }
1094 impl<'a, K, V> DoubleEndedIterator for RangeMut<'a, K, V> {
1095 fn next_back(&mut self) -> Option<(&'a K, &'a mut V)> { self.inner.next_back() }
1098 impl<'a, K: Ord, V> Entry<'a, K, V> {
1099 #[unstable = "matches collection reform v2 specification, waiting for dust to settle"]
1100 /// Returns a mutable reference to the entry if occupied, or the VacantEntry if vacant
1101 pub fn get(self) -> Result<&'a mut V, VacantEntry<'a, K, V>> {
1103 Occupied(entry) => Ok(entry.into_mut()),
1104 Vacant(entry) => Err(entry),
1109 impl<'a, K: Ord, V> VacantEntry<'a, K, V> {
1110 /// Sets the value of the entry with the VacantEntry's key,
1111 /// and returns a mutable reference to it.
1112 #[unstable = "matches collection reform v2 specification, waiting for dust to settle"]
1113 pub fn insert(self, value: V) -> &'a mut V {
1114 self.stack.insert(self.key, value)
1118 impl<'a, K: Ord, V> OccupiedEntry<'a, K, V> {
1119 /// Gets a reference to the value in the entry.
1120 #[unstable = "matches collection reform v2 specification, waiting for dust to settle"]
1121 pub fn get(&self) -> &V {
1125 /// Gets a mutable reference to the value in the entry.
1126 #[unstable = "matches collection reform v2 specification, waiting for dust to settle"]
1127 pub fn get_mut(&mut self) -> &mut V {
1128 self.stack.peek_mut()
1131 /// Converts the entry into a mutable reference to its value.
1132 #[unstable = "matches collection reform v2 specification, waiting for dust to settle"]
1133 pub fn into_mut(self) -> &'a mut V {
1134 self.stack.into_top()
1137 /// Sets the value of the entry with the OccupiedEntry's key,
1138 /// and returns the entry's old value.
1139 #[unstable = "matches collection reform v2 specification, waiting for dust to settle"]
1140 pub fn insert(&mut self, mut value: V) -> V {
1141 mem::swap(self.stack.peek_mut(), &mut value);
1145 /// Takes the value of the entry out of the map, and returns it.
1146 #[unstable = "matches collection reform v2 specification, waiting for dust to settle"]
1147 pub fn remove(self) -> V {
1152 impl<K, V> BTreeMap<K, V> {
1153 /// Gets an iterator over the entries of the map.
1158 /// use std::collections::BTreeMap;
1160 /// let mut map = BTreeMap::new();
1161 /// map.insert(1u, "a");
1162 /// map.insert(2u, "b");
1163 /// map.insert(3u, "c");
1165 /// for (key, value) in map.iter() {
1166 /// println!("{}: {}", key, value);
1169 /// let (first_key, first_value) = map.iter().next().unwrap();
1170 /// assert_eq!((*first_key, *first_value), (1u, "a"));
1173 pub fn iter(&self) -> Iter<K, V> {
1174 let len = self.len();
1175 // NB. The initial capacity for ringbuf is large enough to avoid reallocs in many cases.
1176 let mut lca = RingBuf::new();
1177 lca.push_back(Traverse::traverse(&self.root));
1186 /// Gets a mutable iterator over the entries of the map.
1191 /// use std::collections::BTreeMap;
1193 /// let mut map = BTreeMap::new();
1194 /// map.insert("a", 1u);
1195 /// map.insert("b", 2u);
1196 /// map.insert("c", 3u);
1198 /// // add 10 to the value if the key isn't "a"
1199 /// for (key, value) in map.iter_mut() {
1200 /// if key != &"a" {
1206 pub fn iter_mut(&mut self) -> IterMut<K, V> {
1207 let len = self.len();
1208 let mut lca = RingBuf::new();
1209 lca.push_back(Traverse::traverse(&mut self.root));
1218 /// Gets an owning iterator over the entries of the map.
1223 /// use std::collections::BTreeMap;
1225 /// let mut map = BTreeMap::new();
1226 /// map.insert(1u, "a");
1227 /// map.insert(2u, "b");
1228 /// map.insert(3u, "c");
1230 /// for (key, value) in map.into_iter() {
1231 /// println!("{}: {}", key, value);
1235 pub fn into_iter(self) -> IntoIter<K, V> {
1236 let len = self.len();
1237 let mut lca = RingBuf::new();
1238 lca.push_back(Traverse::traverse(self.root));
1247 /// Gets an iterator over the keys of the map.
1252 /// use std::collections::BTreeMap;
1254 /// let mut a = BTreeMap::new();
1255 /// a.insert(1u, "a");
1256 /// a.insert(2u, "b");
1258 /// let keys: Vec<uint> = a.keys().cloned().collect();
1259 /// assert_eq!(keys, vec![1u,2,]);
1262 pub fn keys<'a>(&'a self) -> Keys<'a, K, V> {
1263 fn first<A, B>((a, _): (A, B)) -> A { a }
1264 let first: fn((&'a K, &'a V)) -> &'a K = first; // coerce to fn pointer
1266 Keys { inner: self.iter().map(first) }
1269 /// Gets an iterator over the values of the map.
1274 /// use std::collections::BTreeMap;
1276 /// let mut a = BTreeMap::new();
1277 /// a.insert(1u, "a");
1278 /// a.insert(2u, "b");
1280 /// let values: Vec<&str> = a.values().cloned().collect();
1281 /// assert_eq!(values, vec!["a","b"]);
1284 pub fn values<'a>(&'a self) -> Values<'a, K, V> {
1285 fn second<A, B>((_, b): (A, B)) -> B { b }
1286 let second: fn((&'a K, &'a V)) -> &'a V = second; // coerce to fn pointer
1288 Values { inner: self.iter().map(second) }
1291 /// Return the number of elements in the map.
1296 /// use std::collections::BTreeMap;
1298 /// let mut a = BTreeMap::new();
1299 /// assert_eq!(a.len(), 0);
1300 /// a.insert(1u, "a");
1301 /// assert_eq!(a.len(), 1);
1304 pub fn len(&self) -> uint { self.length }
1306 /// Return true if the map contains no elements.
1311 /// use std::collections::BTreeMap;
1313 /// let mut a = BTreeMap::new();
1314 /// assert!(a.is_empty());
1315 /// a.insert(1u, "a");
1316 /// assert!(!a.is_empty());
1319 pub fn is_empty(&self) -> bool { self.len() == 0 }
1322 macro_rules! range_impl {
1323 ($root:expr, $min:expr, $max:expr, $as_slices_internal:ident, $iter:ident, $Range:ident,
1324 $edges:ident, [$($mutability:ident)*]) => (
1326 // A deque that encodes two search paths containing (left-to-right):
1327 // a series of truncated-from-the-left iterators, the LCA's doubly-truncated iterator,
1328 // and a series of truncated-from-the-right iterators.
1329 let mut traversals = RingBuf::new();
1330 let (root, min, max) = ($root, $min, $max);
1332 let mut leftmost = None;
1333 let mut rightmost = None;
1335 match (&min, &max) {
1336 (&Unbounded, &Unbounded) => {
1337 traversals.push_back(Traverse::traverse(root))
1339 (&Unbounded, &Included(_)) | (&Unbounded, &Excluded(_)) => {
1340 rightmost = Some(root);
1342 (&Included(_), &Unbounded) | (&Excluded(_), &Unbounded) => {
1343 leftmost = Some(root);
1345 (&Included(min_key), &Included(max_key))
1346 | (&Included(min_key), &Excluded(max_key))
1347 | (&Excluded(min_key), &Included(max_key))
1348 | (&Excluded(min_key), &Excluded(max_key)) => {
1349 // lca represents the Lowest Common Ancestor, above which we never
1350 // walk, since everything else is outside the range to iterate.
1351 // ___________________
1352 // |__0_|_80_|_85_|_90_| (root)
1356 // ___________________
1357 // |__5_|_15_|_30_|_73_|
1361 // ___________________
1362 // |_33_|_58_|_63_|_68_| lca for the range [41, 65]
1363 // | |\___|___/| | iterator at traversals[2]
1368 let mut is_leaf = root.is_leaf();
1369 let mut lca = root.$as_slices_internal();
1371 let slice = lca.slice_from(min_key).slice_to(max_key);
1372 if let [ref $($mutability)* edge] = slice.edges {
1373 // Follow the only edge that leads the node that covers the range.
1374 is_leaf = edge.is_leaf();
1375 lca = edge.$as_slices_internal();
1377 let mut iter = slice.$iter();
1382 // Only change the state of nodes with edges.
1383 leftmost = iter.next_edge_item();
1384 rightmost = iter.next_edge_item_back();
1386 traversals.push_back(iter);
1392 // Keep narrowing the range by going down.
1393 // ___________________
1394 // |_38_|_43_|_48_|_53_|
1395 // | |____|____|____/ iterator at traversals[1]
1398 // ___________________
1399 // |_39_|_40_|_41_|_42_| (leaf, the last leftmost)
1400 // \_________| iterator at traversals[0]
1402 Included(key) | Excluded(key) =>
1403 while let Some(left) = leftmost {
1404 let is_leaf = left.is_leaf();
1405 let mut iter = left.$as_slices_internal().slice_from(key).$iter();
1406 leftmost = if is_leaf {
1409 // Only change the state of nodes with edges.
1410 iter.next_edge_item()
1412 traversals.push_back(iter);
1416 // If the leftmost iterator starts with an element, then it was an exact match.
1417 if let (Excluded(_), Some(leftmost_iter)) = (min, traversals.back_mut()) {
1418 // Drop this excluded element. `next_kv_item` has no effect when
1419 // the next item is an edge.
1420 leftmost_iter.next_kv_item();
1423 // The code for the right side is similar.
1425 Included(key) | Excluded(key) =>
1426 while let Some(right) = rightmost {
1427 let is_leaf = right.is_leaf();
1428 let mut iter = right.$as_slices_internal().slice_to(key).$iter();
1429 rightmost = if is_leaf {
1432 iter.next_edge_item_back()
1434 traversals.push_front(iter);
1438 if let (Excluded(_), Some(rightmost_iter)) = (max, traversals.front_mut()) {
1439 rightmost_iter.next_kv_item_back();
1444 traversals: traversals,
1452 impl<K: Ord, V> BTreeMap<K, V> {
1453 /// Constructs a double-ended iterator over a sub-range of elements in the map, starting
1454 /// at min, and ending at max. If min is `Unbounded`, then it will be treated as "negative
1455 /// infinity", and if max is `Unbounded`, then it will be treated as "positive infinity".
1456 /// Thus range(Unbounded, Unbounded) will yield the whole collection.
1461 /// use std::collections::BTreeMap;
1462 /// use std::collections::Bound::{Included, Unbounded};
1464 /// let mut map = BTreeMap::new();
1465 /// map.insert(3u, "a");
1466 /// map.insert(5u, "b");
1467 /// map.insert(8u, "c");
1468 /// for (&key, &value) in map.range(Included(&4), Included(&8)) {
1469 /// println!("{}: {}", key, value);
1471 /// assert_eq!(Some((&5u, &"b")), map.range(Included(&4), Unbounded).next());
1473 #[unstable = "matches collection reform specification, waiting for dust to settle"]
1474 pub fn range<'a>(&'a self, min: Bound<&K>, max: Bound<&K>) -> Range<'a, K, V> {
1475 range_impl!(&self.root, min, max, as_slices_internal, iter, Range, edges, [])
1478 /// Constructs a mutable double-ended iterator over a sub-range of elements in the map, starting
1479 /// at min, and ending at max. If min is `Unbounded`, then it will be treated as "negative
1480 /// infinity", and if max is `Unbounded`, then it will be treated as "positive infinity".
1481 /// Thus range(Unbounded, Unbounded) will yield the whole collection.
1486 /// use std::collections::BTreeMap;
1487 /// use std::collections::Bound::{Included, Excluded};
1489 /// let mut map: BTreeMap<&str, i32> = ["Alice", "Bob", "Carol", "Cheryl"].iter()
1490 /// .map(|&s| (s, 0))
1492 /// for (_, balance) in map.range_mut(Included(&"B"), Excluded(&"Cheryl")) {
1493 /// *balance += 100;
1495 /// for (name, balance) in map.iter() {
1496 /// println!("{} => {}", name, balance);
1499 #[unstable = "matches collection reform specification, waiting for dust to settle"]
1500 pub fn range_mut<'a>(&'a mut self, min: Bound<&K>, max: Bound<&K>) -> RangeMut<'a, K, V> {
1501 range_impl!(&mut self.root, min, max, as_slices_internal_mut, iter_mut, RangeMut,
1505 /// Gets the given key's corresponding entry in the map for in-place manipulation.
1510 /// use std::collections::BTreeMap;
1511 /// use std::collections::btree_map::Entry;
1513 /// let mut count: BTreeMap<&str, uint> = BTreeMap::new();
1515 /// // count the number of occurrences of letters in the vec
1516 /// for x in vec!["a","b","a","c","a","b"].iter() {
1517 /// match count.entry(*x) {
1518 /// Entry::Vacant(view) => {
1521 /// Entry::Occupied(mut view) => {
1522 /// let v = view.get_mut();
1528 /// assert_eq!(count["a"], 3u);
1530 /// The key must have the same ordering before or after `.to_owned()` is called.
1531 #[unstable = "precise API still under development"]
1532 pub fn entry<'a>(&'a mut self, mut key: K) -> Entry<'a, K, V> {
1533 // same basic logic of `swap` and `pop`, blended together
1534 let mut stack = stack::PartialSearchStack::new(self);
1536 let result = stack.with(move |pusher, node| {
1537 return match Node::search(node, &key) {
1540 Finished(Occupied(OccupiedEntry {
1541 stack: pusher.seal(handle)
1545 match handle.force() {
1546 Leaf(leaf_handle) => {
1547 Finished(Vacant(VacantEntry {
1548 stack: pusher.seal(leaf_handle),
1552 Internal(internal_handle) => {
1554 pusher.push(internal_handle),
1563 Finished(finished) => return finished,
1564 Continue((new_stack, renewed_key)) => {
1580 use std::iter::range_inclusive;
1582 use super::{BTreeMap, Occupied, Vacant};
1583 use Bound::{self, Included, Excluded, Unbounded};
1586 fn test_basic_large() {
1587 let mut map = BTreeMap::new();
1589 assert_eq!(map.len(), 0);
1591 for i in range(0, size) {
1592 assert_eq!(map.insert(i, 10*i), None);
1593 assert_eq!(map.len(), i + 1);
1596 for i in range(0, size) {
1597 assert_eq!(map.get(&i).unwrap(), &(i*10));
1600 for i in range(size, size*2) {
1601 assert_eq!(map.get(&i), None);
1604 for i in range(0, size) {
1605 assert_eq!(map.insert(i, 100*i), Some(10*i));
1606 assert_eq!(map.len(), size);
1609 for i in range(0, size) {
1610 assert_eq!(map.get(&i).unwrap(), &(i*100));
1613 for i in range(0, size/2) {
1614 assert_eq!(map.remove(&(i*2)), Some(i*200));
1615 assert_eq!(map.len(), size - i - 1);
1618 for i in range(0, size/2) {
1619 assert_eq!(map.get(&(2*i)), None);
1620 assert_eq!(map.get(&(2*i+1)).unwrap(), &(i*200 + 100));
1623 for i in range(0, size/2) {
1624 assert_eq!(map.remove(&(2*i)), None);
1625 assert_eq!(map.remove(&(2*i+1)), Some(i*200 + 100));
1626 assert_eq!(map.len(), size/2 - i - 1);
1631 fn test_basic_small() {
1632 let mut map = BTreeMap::new();
1633 assert_eq!(map.remove(&1), None);
1634 assert_eq!(map.get(&1), None);
1635 assert_eq!(map.insert(1u, 1u), None);
1636 assert_eq!(map.get(&1), Some(&1));
1637 assert_eq!(map.insert(1, 2), Some(1));
1638 assert_eq!(map.get(&1), Some(&2));
1639 assert_eq!(map.insert(2, 4), None);
1640 assert_eq!(map.get(&2), Some(&4));
1641 assert_eq!(map.remove(&1), Some(2));
1642 assert_eq!(map.remove(&2), Some(4));
1643 assert_eq!(map.remove(&1), None);
1651 let mut map: BTreeMap<uint, uint> = range(0, size).map(|i| (i, i)).collect();
1653 fn test<T>(size: uint, mut iter: T) where T: Iterator<Item=(uint, uint)> {
1654 for i in range(0, size) {
1655 assert_eq!(iter.size_hint(), (size - i, Some(size - i)));
1656 assert_eq!(iter.next().unwrap(), (i, i));
1658 assert_eq!(iter.size_hint(), (0, Some(0)));
1659 assert_eq!(iter.next(), None);
1661 test(size, map.iter().map(|(&k, &v)| (k, v)));
1662 test(size, map.iter_mut().map(|(&k, &mut v)| (k, v)));
1663 test(size, map.into_iter());
1667 fn test_iter_rev() {
1671 let mut map: BTreeMap<uint, uint> = range(0, size).map(|i| (i, i)).collect();
1673 fn test<T>(size: uint, mut iter: T) where T: Iterator<Item=(uint, uint)> {
1674 for i in range(0, size) {
1675 assert_eq!(iter.size_hint(), (size - i, Some(size - i)));
1676 assert_eq!(iter.next().unwrap(), (size - i - 1, size - i - 1));
1678 assert_eq!(iter.size_hint(), (0, Some(0)));
1679 assert_eq!(iter.next(), None);
1681 test(size, map.iter().rev().map(|(&k, &v)| (k, v)));
1682 test(size, map.iter_mut().rev().map(|(&k, &mut v)| (k, v)));
1683 test(size, map.into_iter().rev());
1687 fn test_iter_mixed() {
1691 let mut map: BTreeMap<uint, uint> = range(0, size).map(|i| (i, i)).collect();
1693 fn test<T>(size: uint, mut iter: T)
1694 where T: Iterator<Item=(uint, uint)> + DoubleEndedIterator {
1695 for i in range(0, size / 4) {
1696 assert_eq!(iter.size_hint(), (size - i * 2, Some(size - i * 2)));
1697 assert_eq!(iter.next().unwrap(), (i, i));
1698 assert_eq!(iter.next_back().unwrap(), (size - i - 1, size - i - 1));
1700 for i in range(size / 4, size * 3 / 4) {
1701 assert_eq!(iter.size_hint(), (size * 3 / 4 - i, Some(size * 3 / 4 - i)));
1702 assert_eq!(iter.next().unwrap(), (i, i));
1704 assert_eq!(iter.size_hint(), (0, Some(0)));
1705 assert_eq!(iter.next(), None);
1707 test(size, map.iter().map(|(&k, &v)| (k, v)));
1708 test(size, map.iter_mut().map(|(&k, &mut v)| (k, v)));
1709 test(size, map.into_iter());
1713 fn test_range_small() {
1717 let map: BTreeMap<uint, uint> = range(0, size).map(|i| (i, i)).collect();
1720 for ((&k, &v), i) in map.range(Included(&2), Unbounded).zip(range(2u, size)) {
1725 assert_eq!(j, size - 2);
1729 fn test_range_1000() {
1731 let map: BTreeMap<uint, uint> = range(0, size).map(|i| (i, i)).collect();
1733 fn test(map: &BTreeMap<uint, uint>, size: uint, min: Bound<&uint>, max: Bound<&uint>) {
1734 let mut kvs = map.range(min, max).map(|(&k, &v)| (k, v));
1735 let mut pairs = range(0, size).map(|i| (i, i));
1737 for (kv, pair) in kvs.by_ref().zip(pairs.by_ref()) {
1738 assert_eq!(kv, pair);
1740 assert_eq!(kvs.next(), None);
1741 assert_eq!(pairs.next(), None);
1743 test(&map, size, Included(&0), Excluded(&size));
1744 test(&map, size, Unbounded, Excluded(&size));
1745 test(&map, size, Included(&0), Included(&(size - 1)));
1746 test(&map, size, Unbounded, Included(&(size - 1)));
1747 test(&map, size, Included(&0), Unbounded);
1748 test(&map, size, Unbounded, Unbounded);
1754 let map: BTreeMap<uint, uint> = range(0, size).map(|i| (i, i)).collect();
1756 for i in range(0, size) {
1757 for j in range(i, size) {
1758 let mut kvs = map.range(Included(&i), Included(&j)).map(|(&k, &v)| (k, v));
1759 let mut pairs = range_inclusive(i, j).map(|i| (i, i));
1761 for (kv, pair) in kvs.by_ref().zip(pairs.by_ref()) {
1762 assert_eq!(kv, pair);
1764 assert_eq!(kvs.next(), None);
1765 assert_eq!(pairs.next(), None);
1772 let xs = [(1i, 10i), (2, 20), (3, 30), (4, 40), (5, 50), (6, 60)];
1774 let mut map: BTreeMap<int, int> = xs.iter().map(|&x| x).collect();
1776 // Existing key (insert)
1777 match map.entry(1) {
1778 Vacant(_) => unreachable!(),
1779 Occupied(mut view) => {
1780 assert_eq!(view.get(), &10);
1781 assert_eq!(view.insert(100), 10);
1784 assert_eq!(map.get(&1).unwrap(), &100);
1785 assert_eq!(map.len(), 6);
1788 // Existing key (update)
1789 match map.entry(2) {
1790 Vacant(_) => unreachable!(),
1791 Occupied(mut view) => {
1792 let v = view.get_mut();
1796 assert_eq!(map.get(&2).unwrap(), &200);
1797 assert_eq!(map.len(), 6);
1799 // Existing key (take)
1800 match map.entry(3) {
1801 Vacant(_) => unreachable!(),
1803 assert_eq!(view.remove(), 30);
1806 assert_eq!(map.get(&3), None);
1807 assert_eq!(map.len(), 5);
1810 // Inexistent key (insert)
1811 match map.entry(10) {
1812 Occupied(_) => unreachable!(),
1814 assert_eq!(*view.insert(1000), 1000);
1817 assert_eq!(map.get(&10).unwrap(), &1000);
1818 assert_eq!(map.len(), 6);
1830 use std::rand::{weak_rng, Rng};
1831 use test::{Bencher, black_box};
1833 use super::BTreeMap;
1834 use bench::{insert_rand_n, insert_seq_n, find_rand_n, find_seq_n};
1837 pub fn insert_rand_100(b: &mut Bencher) {
1838 let mut m : BTreeMap<uint,uint> = BTreeMap::new();
1839 insert_rand_n(100, &mut m, b,
1840 |m, i| { m.insert(i, 1); },
1841 |m, i| { m.remove(&i); });
1845 pub fn insert_rand_10_000(b: &mut Bencher) {
1846 let mut m : BTreeMap<uint,uint> = BTreeMap::new();
1847 insert_rand_n(10_000, &mut m, b,
1848 |m, i| { m.insert(i, 1); },
1849 |m, i| { m.remove(&i); });
1854 pub fn insert_seq_100(b: &mut Bencher) {
1855 let mut m : BTreeMap<uint,uint> = BTreeMap::new();
1856 insert_seq_n(100, &mut m, b,
1857 |m, i| { m.insert(i, 1); },
1858 |m, i| { m.remove(&i); });
1862 pub fn insert_seq_10_000(b: &mut Bencher) {
1863 let mut m : BTreeMap<uint,uint> = BTreeMap::new();
1864 insert_seq_n(10_000, &mut m, b,
1865 |m, i| { m.insert(i, 1); },
1866 |m, i| { m.remove(&i); });
1871 pub fn find_rand_100(b: &mut Bencher) {
1872 let mut m : BTreeMap<uint,uint> = BTreeMap::new();
1873 find_rand_n(100, &mut m, b,
1874 |m, i| { m.insert(i, 1); },
1875 |m, i| { m.get(&i); });
1879 pub fn find_rand_10_000(b: &mut Bencher) {
1880 let mut m : BTreeMap<uint,uint> = BTreeMap::new();
1881 find_rand_n(10_000, &mut m, b,
1882 |m, i| { m.insert(i, 1); },
1883 |m, i| { m.get(&i); });
1888 pub fn find_seq_100(b: &mut Bencher) {
1889 let mut m : BTreeMap<uint,uint> = BTreeMap::new();
1890 find_seq_n(100, &mut m, b,
1891 |m, i| { m.insert(i, 1); },
1892 |m, i| { m.get(&i); });
1896 pub fn find_seq_10_000(b: &mut Bencher) {
1897 let mut m : BTreeMap<uint,uint> = BTreeMap::new();
1898 find_seq_n(10_000, &mut m, b,
1899 |m, i| { m.insert(i, 1); },
1900 |m, i| { m.get(&i); });
1903 fn bench_iter(b: &mut Bencher, size: uint) {
1904 let mut map = BTreeMap::<uint, uint>::new();
1905 let mut rng = weak_rng();
1907 for _ in range(0, size) {
1908 map.insert(rng.gen(), rng.gen());
1912 for entry in map.iter() {
1919 pub fn iter_20(b: &mut Bencher) {
1924 pub fn iter_1000(b: &mut Bencher) {
1925 bench_iter(b, 1000);
1929 pub fn iter_100000(b: &mut Bencher) {
1930 bench_iter(b, 100000);