Struct OSBTreeMap 

pub struct OSBTreeMap<K, V> { /* private fields */ }

An ordered map based on a B-Tree.

Given a key type with a total order, an ordered map stores its entries in key order. That means that keys must be of a type that implements the Ord trait, such that two keys can always be compared to determine their Ordering. Examples of keys with a total order are strings with lexicographical order, and numbers with their natural order.

Iterators obtained from functions such as OSBTreeMap::iter, OSBTreeMap::into_iter, OSBTreeMap::values, or OSBTreeMap::keys produce their items in key order, and take worst-case logarithmic and amortized constant time per item returned.

It is a logic error for a key to be modified in such a way that the key’s ordering relative to any other key, as determined by the Ord trait, changes while it is in the map. This is normally only possible through Cell, RefCell, global state, I/O, or unsafe code. The behavior resulting from such a logic error is not specified, but will be encapsulated to the OSBTreeMap that observed the logic error and not result in undefined behavior. This could include panics, incorrect results, aborts, memory leaks, and non-termination.

Examples

use wabi_tree::OSBTreeMap;

// type inference lets us omit an explicit type signature (which
// would be `OSBTreeMap<&str, &str>` in this example).
let mut movie_reviews = OSBTreeMap::new();

// review some movies.
movie_reviews.insert("Office Space",       "Deals with real issues in the workplace.");
movie_reviews.insert("Pulp Fiction",       "Masterpiece.");
movie_reviews.insert("The Godfather",      "Very enjoyable.");
movie_reviews.insert("The Blues Brothers", "Eye lyked it a lot.");

// check for a specific one.
if !movie_reviews.contains_key("Les Miserables") {
    println!("We've got {} reviews, but Les Miserables ain't one.",
             movie_reviews.len());
}

// oops, this review has a lot of spelling mistakes, let's delete it.
movie_reviews.remove("The Blues Brothers");

// look up the values associated with some keys.
let to_find = ["Up!", "Office Space"];
for movie in &to_find {
    match movie_reviews.get(movie) {
       Some(review) => println!("{movie}: {review}"),
       None => println!("{movie} is unreviewed.")
    }
}

// Look up the value for a key (will panic if the key is not found).
println!("Movie review: {}", movie_reviews["Office Space"]);

// iterate over everything.
for (movie, review) in &movie_reviews {
    println!("{movie}: \"{review}\"");
}

An OSBTreeMap with a known list of items can be initialized from an array:

use wabi_tree::OSBTreeMap;

let solar_distance = OSBTreeMap::from([
    ("Mercury", 0.4),
    ("Venus", 0.7),
    ("Earth", 1.0),
    ("Mars", 1.5),
]);

Entry API

OSBTreeMap implements an Entry API, which allows for complex methods of getting, setting, updating and removing keys and their values:

use wabi_tree::OSBTreeMap;

// type inference lets us omit an explicit type signature (which
// would be `OSBTreeMap<&str, u8>` in this example).
let mut player_stats = OSBTreeMap::new();

fn random_stat_buff() -> u8 {
    // could actually return some random value here - let's just return
    // some fixed value for now
    42
}

// insert a key only if it doesn't already exist
player_stats.entry("health").or_insert(100);

// insert a key using a function that provides a new value only if it
// doesn't already exist
player_stats.entry("defence").or_insert_with(random_stat_buff);

// update a key, guarding against the key possibly not being set
let stat = player_stats.entry("attack").or_insert(100);
*stat += random_stat_buff();

// modify an entry before an insert with in-place mutation
player_stats.entry("mana").and_modify(|mana| *mana += 200).or_insert(100);

Background

A B-tree is (like) a binary search tree, but adapted to the natural granularity that modern machines like to consume data at. This means that each node contains an entire array of elements, instead of just a single element.

B-Trees represent a fundamental compromise between cache-efficiency and actually minimizing the amount of work performed in a search. In theory, a binary search tree (BST) is the optimal choice for a sorted map, as a perfectly balanced BST performs the theoretical minimum number of comparisons necessary to find an element (log₂n). However, in practice the way this is done is very inefficient for modern computer architectures. In particular, every element is stored in its own individually heap-allocated node. This means that every single insertion triggers a heap-allocation, and every comparison is a potential cache-miss due to the indirection. Since both heap-allocations and cache-misses are notably expensive in practice, we are forced to, at the very least, reconsider the BST strategy.

A B-Tree instead makes each node contain B-1 to 2B-1 elements in a contiguous array. By doing this, we reduce the number of allocations by a factor of B, and improve cache efficiency in searches. However, this does mean that searches will have to do more comparisons on average. The precise number of comparisons depends on the node search strategy used. For optimal cache efficiency, one could search the nodes linearly. For optimal comparisons, one could search the node using binary search. As a compromise, one could also perform a linear search that initially only checks every i^th element for some choice of i.

Our implementation uses binary search within each node, giving O(log B) comparisons per node and O(log B * log n) = O(log n) total comparisons for tree operations. This matches the asymptotic complexity of a standard BST while providing better cache locality due to the larger node size.

Implementations

impl<K, V> OSBTreeMap<K, V>

pub fn with_capacity(capacity: usize) -> Self

Creates an empty map with capacity for at least capacity elements.

This is an extension and is not part of the standard BTreeMap API.

Examples

use wabi_tree::OSBTreeMap;

let map: OSBTreeMap<i32, i32> = OSBTreeMap::with_capacity(32);
assert!(map.is_empty());

Complexity

O(capacity) for memory allocation.

pub fn capacity(&self) -> usize

Returns the current capacity for the map.

This is an extension and is not part of the standard BTreeMap API.

Examples

use wabi_tree::OSBTreeMap;

let map: OSBTreeMap<i32, i32> = OSBTreeMap::with_capacity(32);
assert_eq!(map.capacity(), 32);

Complexity

O(1)

impl<K: Clone + Ord, V> OSBTreeMap<K, V>

pub fn get_by_rank(&self, rank: usize) -> Option<(&K, &V)>

Returns the key-value pair at position rank in sorted order.

This is an order-statistic extension and is not part of the standard BTreeMap API.

The rank is zero-based. Returns None if rank is out of bounds.

Complexity

O(log n)

Examples

use wabi_tree::OSBTreeMap;

let mut map = OSBTreeMap::new();
map.insert("a", 10);
map.insert("c", 30);
map.insert("b", 20);

let (key, value) = map.get_by_rank(1).unwrap();
assert_eq!((key, value), (&"b", &20));
assert!(map.get_by_rank(3).is_none());

pub fn get_by_rank_mut(&mut self, rank: usize) -> Option<(&K, &mut V)>

Returns the key and a mutable reference to the value at position rank in sorted order.

This is an order-statistic extension and is not part of the standard BTreeMap API.

The rank is zero-based. Returns None if rank is out of bounds. The key is returned as a shared reference because mutating it would violate the map’s ordering invariants.

Complexity

O(log n)

Examples

use wabi_tree::OSBTreeMap;

let mut map = OSBTreeMap::new();
map.insert(10, "a");
map.insert(5, "b");

if let Some((key, value)) = map.get_by_rank_mut(0) {
    assert_eq!(*key, 5);
    *value = "updated";
}

assert_eq!(map.get(&5), Some(&"updated"));

pub fn rank_of<Q>(&self, key: &Q) -> Option<usize>

where K: Borrow<Q>, Q: ?Sized + Ord,

Returns the zero-based rank of key in sorted order, or None if the key is not present.

This is an order-statistic extension and is not part of the standard BTreeMap API.

Complexity

O(log n)

Examples

use wabi_tree::OSBTreeMap;

let mut map = OSBTreeMap::new();
map.insert(10, "a");
map.insert(20, "b");

assert_eq!(map.rank_of(&10), Some(0));
assert_eq!(map.rank_of(&15), None);

impl<K, V> OSBTreeMap<K, V>

pub const fn new() -> OSBTreeMap<K, V>

Makes a new, empty OSBTreeMap.

Does not allocate anything on its own.

Complexity

O(1)

Examples

use wabi_tree::OSBTreeMap;

let mut map = OSBTreeMap::new();

// entries can now be inserted into the empty map
map.insert(1, "a");

pub fn clear(&mut self)

Clears the map, removing all elements.

Complexity

O(n)

Examples

use wabi_tree::OSBTreeMap;

let mut a = OSBTreeMap::new();
a.insert(1, "a");
a.clear();
assert!(a.is_empty());

pub fn get<Q>(&self, key: &Q) -> Option<&V>

where K: Borrow<Q> + Ord + Clone, Q: ?Sized + Ord,

Returns a reference to the value corresponding to the key.

The key may be any borrowed form of the map’s key type, but the ordering on the borrowed form must match the ordering on the key type.

Complexity

O(log n)

Examples

use wabi_tree::OSBTreeMap;

let mut map = OSBTreeMap::new();
map.insert(1, "a");
assert_eq!(map.get(&1), Some(&"a"));
assert_eq!(map.get(&2), None);

pub fn get_key_value<Q>(&self, k: &Q) -> Option<(&K, &V)>

where K: Borrow<Q> + Ord + Clone, Q: ?Sized + Ord,

Returns the key-value pair corresponding to the supplied key. This is potentially useful:

• for key types where non-identical keys can be considered equal;
• for getting the &K stored key value from a borrowed &Q lookup key; or
• for getting a reference to a key with the same lifetime as the collection.

The supplied key may be any borrowed form of the map’s key type, but the ordering on the borrowed form must match the ordering on the key type.

Examples

use core::cmp::Ordering;
use wabi_tree::OSBTreeMap;

#[derive(Clone, Copy, Debug)]
struct S {
    id: u32,
    name: &'static str, // ignored by equality and ordering operations
}

impl PartialEq for S {
    fn eq(&self, other: &S) -> bool {
        self.id == other.id
    }
}

impl Eq for S {}

impl PartialOrd for S {
    fn partial_cmp(&self, other: &S) -> Option<Ordering> {
        self.id.partial_cmp(&other.id)
    }
}

impl Ord for S {
    fn cmp(&self, other: &S) -> Ordering {
        self.id.cmp(&other.id)
    }
}

let j_a = S { id: 1, name: "Jessica" };
let j_b = S { id: 1, name: "Jess" };
let p = S { id: 2, name: "Paul" };
assert_eq!(j_a, j_b);

let mut map = OSBTreeMap::new();
map.insert(j_a, "Paris");
assert_eq!(map.get_key_value(&j_a), Some((&j_a, &"Paris")));
assert_eq!(map.get_key_value(&j_b), Some((&j_a, &"Paris"))); // the notable case
assert_eq!(map.get_key_value(&p), None);

Complexity

O(log n)

pub fn first_key_value(&self) -> Option<(&K, &V)>

where K: Ord + Clone,

Returns the first key-value pair in the map. The key in this pair is the minimum key in the map.

Examples

use wabi_tree::OSBTreeMap;

let mut map = OSBTreeMap::new();
assert_eq!(map.first_key_value(), None);
map.insert(1, "b");
map.insert(2, "a");
assert_eq!(map.first_key_value(), Some((&1, &"b")));

Complexity

O(1) - uses cached first leaf handle.

pub fn first_entry(&mut self) -> Option<OccupiedEntry<'_, K, V>>

where K: Ord + Clone,

Returns the first entry in the map for in-place manipulation. The key of this entry is the minimum key in the map.

Examples

use wabi_tree::OSBTreeMap;

let mut map = OSBTreeMap::new();
map.insert(1, "a");
map.insert(2, "b");
if let Some(mut entry) = map.first_entry() {
    if *entry.key() > 0 {
        entry.insert("first");
    }
}
assert_eq!(*map.get(&1).unwrap(), "first");
assert_eq!(*map.get(&2).unwrap(), "b");

Complexity

O(1) - uses cached first leaf handle.

pub fn pop_first(&mut self) -> Option<(K, V)>

where K: Clone + Ord,

Removes and returns the first element in the map. The key of this element is the minimum key that was in the map.

Examples

Draining elements in ascending order, while keeping a usable map each iteration.

use wabi_tree::OSBTreeMap;

let mut map = OSBTreeMap::new();
map.insert(1, "a");
map.insert(2, "b");
while let Some((key, _val)) = map.pop_first() {
    assert!(map.iter().all(|(k, _v)| *k > key));
}
assert!(map.is_empty());

Complexity

O(log n)

pub fn last_key_value(&self) -> Option<(&K, &V)>

where K: Ord + Clone,

Returns the last key-value pair in the map. The key in this pair is the maximum key in the map.

Examples

use wabi_tree::OSBTreeMap;

let mut map = OSBTreeMap::new();
assert_eq!(map.last_key_value(), None);
map.insert(1, "b");
map.insert(2, "a");
assert_eq!(map.last_key_value(), Some((&2, &"a")));

Complexity

O(1) - uses cached last leaf handle.

pub fn last_entry(&mut self) -> Option<OccupiedEntry<'_, K, V>>

where K: Ord + Clone,

Returns the last entry in the map for in-place manipulation. The key of this entry is the maximum key in the map.

Examples

use wabi_tree::OSBTreeMap;

let mut map = OSBTreeMap::new();
map.insert(1, "a");
map.insert(2, "b");
if let Some(mut entry) = map.last_entry() {
    if *entry.key() > 0 {
        entry.insert("last");
    }
}
assert_eq!(*map.get(&1).unwrap(), "a");
assert_eq!(*map.get(&2).unwrap(), "last");

Complexity

O(1) - uses cached last leaf handle.

pub fn pop_last(&mut self) -> Option<(K, V)>

where K: Clone + Ord,

Removes and returns the last element in the map. The key of this element is the maximum key that was in the map.

Examples

Draining elements in descending order, while keeping a usable map each iteration.

use wabi_tree::OSBTreeMap;

let mut map = OSBTreeMap::new();
map.insert(1, "a");
map.insert(2, "b");
while let Some((key, _val)) = map.pop_last() {
    assert!(map.iter().all(|(k, _v)| *k < key));
}
assert!(map.is_empty());

Complexity

O(log n)

pub fn contains_key<Q>(&self, key: &Q) -> bool

where K: Borrow<Q> + Ord + Clone, Q: ?Sized + Ord,

Returns true if the map contains a value for the specified key.

The key may be any borrowed form of the map’s key type, but the ordering on the borrowed form must match the ordering on the key type.

Examples

use wabi_tree::OSBTreeMap;

let mut map = OSBTreeMap::new();
map.insert(1, "a");
assert_eq!(map.contains_key(&1), true);
assert_eq!(map.contains_key(&2), false);

Complexity

O(log n)

pub fn get_mut<Q>(&mut self, key: &Q) -> Option<&mut V>

where K: Borrow<Q> + Ord + Clone, Q: ?Sized + Ord,

Returns a mutable reference to the value corresponding to the key.

The key may be any borrowed form of the map’s key type, but the ordering on the borrowed form must match the ordering on the key type.

Examples

use wabi_tree::OSBTreeMap;

let mut map = OSBTreeMap::new();
map.insert(1, "a");
if let Some(x) = map.get_mut(&1) {
    *x = "b";
}
assert_eq!(map[&1], "b");

Complexity

O(log n)

pub fn insert(&mut self, key: K, value: V) -> Option<V>

where K: Clone + Ord,

Inserts a key-value pair into the map.

If the map did not have this key present, None is returned.

If the map did have this key present, the value is updated, and the old value is returned. The key is not updated, though; this matters for types that can be == without being identical. See the module-level documentation for more.

Examples

use wabi_tree::OSBTreeMap;

let mut map = OSBTreeMap::new();
assert_eq!(map.insert(37, "a"), None);
assert_eq!(map.is_empty(), false);

map.insert(37, "b");
assert_eq!(map.insert(37, "c"), Some("b"));
assert_eq!(map[&37], "c");

Complexity

O(log n)

pub fn remove<Q>(&mut self, key: &Q) -> Option<V>

where K: Borrow<Q> + Clone + Ord, Q: ?Sized + Ord,

Removes a key from the map, returning the value at the key if the key was previously in the map.

The key may be any borrowed form of the map’s key type, but the ordering on the borrowed form must match the ordering on the key type.

Examples

use wabi_tree::OSBTreeMap;

let mut map = OSBTreeMap::new();
map.insert(1, "a");
assert_eq!(map.remove(&1), Some("a"));
assert_eq!(map.remove(&1), None);

Complexity

O(log n)

pub fn remove_entry<Q>(&mut self, key: &Q) -> Option<(K, V)>

where K: Borrow<Q> + Clone + Ord, Q: ?Sized + Ord,

Removes a key from the map, returning the stored key and value if the key was previously in the map.

The key may be any borrowed form of the map’s key type, but the ordering on the borrowed form must match the ordering on the key type.

Examples

use wabi_tree::OSBTreeMap;

let mut map = OSBTreeMap::new();
map.insert(1, "a");
assert_eq!(map.remove_entry(&1), Some((1, "a")));
assert_eq!(map.remove_entry(&1), None);

Complexity

O(log n)

pub fn retain<F>(&mut self, f: F)

where K: Clone + Ord, F: FnMut(&K, &mut V) -> bool,

Retains only the elements specified by the predicate.

In other words, remove all pairs (k, v) for which f(&k, &mut v) returns false. The elements are visited in ascending key order.

Examples

use wabi_tree::OSBTreeMap;

let mut map: OSBTreeMap<i32, i32> = (0..8).map(|x| (x, x * 10)).collect();
// Keep only the elements with even-numbered keys.
map.retain(|&k, _| k % 2 == 0);
assert!(map.into_iter().eq(vec![(0, 0), (2, 20), (4, 40), (6, 60)]));

Complexity

O(n log n) in the worst case (when many elements are removed).

pub fn append(&mut self, other: &mut Self)

where K: Clone + Ord,

Moves all elements from other into self, leaving other empty.

If a key from other is already present in self, the respective value from self will be overwritten with the respective value from other.

Examples

use wabi_tree::OSBTreeMap;

let mut a = OSBTreeMap::new();
a.insert(1, "a");
a.insert(2, "b");
a.insert(3, "c"); // Note: Key (3) also present in b.

let mut b = OSBTreeMap::new();
b.insert(3, "d"); // Note: Key (3) also present in a.
b.insert(4, "e");
b.insert(5, "f");

a.append(&mut b);

assert_eq!(a.len(), 5);
assert_eq!(b.len(), 0);

assert_eq!(a[&1], "a");
assert_eq!(a[&2], "b");
assert_eq!(a[&3], "d");
assert_eq!(a[&4], "e");
assert_eq!(a[&5], "f");

Complexity

O(m log(n + m)), where m is the size of other and n is the size of self.

pub fn range<T, R>(&self, range: R) -> Range<'_, K, V>

where T: ?Sized + Ord, K: Borrow<T> + Ord + Clone, R: RangeBounds<T>,

Constructs a double-ended iterator over a sub-range of elements in the map. The simplest way is to use the range syntax min..max, thus range(min..max) will yield elements from min (inclusive) to max (exclusive). The range may also be entered as (Bound<T>, Bound<T>), so for example range((Excluded(4), Included(10))) will yield a left-exclusive, right-inclusive range from 4 to 10.

Panics

Panics if range start > end. Panics if range start == end and both bounds are Excluded.

Examples

use core::ops::Bound::Included;
use wabi_tree::OSBTreeMap;

let mut map = OSBTreeMap::new();
map.insert(3, "a");
map.insert(5, "b");
map.insert(8, "c");
for (&key, &value) in map.range((Included(&4), Included(&8))) {
    println!("{key}: {value}");
}
assert_eq!(Some((&5, &"b")), map.range(4..).next());

Complexity

O(log n) to create the iterator; each iteration step is O(1) amortized.

pub fn range_mut<T, R>(&mut self, range: R) -> RangeMut<'_, K, V>

where T: ?Sized + Ord, K: Borrow<T> + Ord + Clone, R: RangeBounds<T>,

Constructs a mutable double-ended iterator over a sub-range of elements in the map. The simplest way is to use the range syntax min..max, thus range(min..max) will yield elements from min (inclusive) to max (exclusive). The range may also be entered as (Bound<T>, Bound<T>), so for example range((Excluded(4), Included(10))) will yield a left-exclusive, right-inclusive range from 4 to 10.

Panics

Panics if range start > end. Panics if range start == end and both bounds are Excluded.

Examples

use wabi_tree::OSBTreeMap;

let mut map: OSBTreeMap<&str, i32> =
    [("Alice", 0), ("Bob", 0), ("Carol", 0), ("Cheryl", 0)].into();
for (_, balance) in map.range_mut("B".."Cheryl") {
    *balance += 100;
}
for (name, balance) in &map {
    println!("{name} => {balance}");
}

Complexity

O(log n) to create the iterator; each iteration step is O(1) amortized.

pub fn entry(&mut self, key: K) -> Entry<'_, K, V>

where K: Ord + Clone,

Gets the given key’s corresponding entry in the map for in-place manipulation.

Examples

use wabi_tree::OSBTreeMap;

let mut count: OSBTreeMap<&str, usize> = OSBTreeMap::new();

// count the number of occurrences of letters in the vec
for x in ["a", "b", "a", "c", "a", "b"] {
    count.entry(x).and_modify(|curr| *curr += 1).or_insert(1);
}

assert_eq!(count["a"], 3);
assert_eq!(count["b"], 2);
assert_eq!(count["c"], 1);

Complexity

O(log n)

pub fn split_off<Q: Ord>(&mut self, key: &Q) -> Self

where K: Borrow<Q> + Clone + Ord,

Splits the collection into two at the given key. Returns everything after the given key, including the key. If the key is not present, the split will occur at the nearest greater key, or return an empty map if no such key exists.

Examples

use wabi_tree::OSBTreeMap;

let mut a = OSBTreeMap::new();
a.insert(1, "a");
a.insert(2, "b");
a.insert(3, "c");
a.insert(17, "d");
a.insert(41, "e");

let b = a.split_off(&3);

assert_eq!(a.len(), 2);
assert_eq!(b.len(), 3);

assert_eq!(a[&1], "a");
assert_eq!(a[&2], "b");

assert_eq!(b[&3], "c");
assert_eq!(b[&17], "d");
assert_eq!(b[&41], "e");

Complexity

O(m log(n)), where m is the number of elements being split off.

pub fn extract_if<F, R>( &mut self, range: R, pred: F, ) -> ExtractIf<'_, K, V, R, F>

where K: Clone + Ord, R: RangeBounds<K>, F: FnMut(&K, &mut V) -> bool,

Creates an iterator that visits elements (key-value pairs) in the specified range in ascending key order and uses a closure to determine if an element should be removed.

If the closure returns true, the element is removed from the map and yielded. If the closure returns false, or panics, the element remains in the map and will not be yielded.

The iterator also lets you mutate the value of each element in the closure, regardless of whether you choose to keep or remove it.

If the returned ExtractIf is not exhausted, e.g. because it is dropped without iterating or the iteration short-circuits, then the remaining elements will be retained. Use retain with a negated predicate if you do not need the returned iterator.

Examples

use wabi_tree::OSBTreeMap;

// Splitting a map into even and odd keys, reusing the original map:
let mut map: OSBTreeMap<i32, i32> = (0..8).map(|x| (x, x)).collect();
let evens: OSBTreeMap<_, _> = map.extract_if(.., |k, _v| k % 2 == 0).collect();
let odds = map;
assert_eq!(evens.keys().copied().collect::<Vec<_>>(), [0, 2, 4, 6]);
assert_eq!(odds.keys().copied().collect::<Vec<_>>(), [1, 3, 5, 7]);

// Splitting a map into low and high halves, reusing the original map:
let mut map: OSBTreeMap<i32, i32> = (0..8).map(|x| (x, x)).collect();
let low: OSBTreeMap<_, _> = map.extract_if(0..4, |_k, _v| true).collect();
let high = map;
assert_eq!(low.keys().copied().collect::<Vec<_>>(), [0, 1, 2, 3]);
assert_eq!(high.keys().copied().collect::<Vec<_>>(), [4, 5, 6, 7]);

Complexity

O(m + k log n) where m is the number of elements in the range and k is the number of elements extracted. All keys in the range are collected upfront, then each extracted element requires a O(log n) removal.

pub fn into_keys(self) -> IntoKeys<K, V>

Creates a consuming iterator visiting all the keys, in sorted order. The map cannot be used after calling this. The iterator element type is K.

Examples

use wabi_tree::OSBTreeMap;

let mut a = OSBTreeMap::new();
a.insert(2, "b");
a.insert(1, "a");

let keys: Vec<_> = a.into_keys().collect();
assert_eq!(keys, [1, 2]);

Complexity

O(n) to create the iterator (drains all elements); iteration is O(1) per element.

pub fn into_values(self) -> IntoValues<K, V>

Creates a consuming iterator visiting all the values, in order by key. The map cannot be used after calling this. The iterator element type is V.

Examples

use wabi_tree::OSBTreeMap;

let mut a = OSBTreeMap::new();
a.insert(1, "hello");
a.insert(2, "goodbye");

let values: Vec<_> = a.into_values().collect();
assert_eq!(values, ["hello", "goodbye"]);

Complexity

O(n) to create the iterator (drains all elements); iteration is O(1) per element.

pub fn iter(&self) -> Iter<'_, K, V>

Gets an iterator over the entries of the map, sorted by key.

Examples

use wabi_tree::OSBTreeMap;

let mut map = OSBTreeMap::new();
map.insert(3, "c");
map.insert(2, "b");
map.insert(1, "a");

for (key, value) in map.iter() {
    println!("{key}: {value}");
}

let (first_key, first_value) = map.iter().next().unwrap();
assert_eq!((*first_key, *first_value), (1, "a"));

Complexity

O(1) to create the iterator; O(1) per iteration step via linked leaves.

pub fn iter_mut(&mut self) -> IterMut<'_, K, V>

Gets a mutable iterator over the entries of the map, sorted by key.

Examples

use wabi_tree::OSBTreeMap;

let mut map = OSBTreeMap::from([
   ("a", 1),
   ("b", 2),
   ("c", 3),
]);

// add 10 to the value if the key isn't "a"
for (key, value) in map.iter_mut() {
    if key != &"a" {
        *value += 10;
    }
}

Complexity

O(1) to create the iterator; O(1) per iteration step via linked leaves.

pub fn keys(&self) -> Keys<'_, K, V>

Gets an iterator over the keys of the map, in sorted order.

Examples

use wabi_tree::OSBTreeMap;

let mut a = OSBTreeMap::new();
a.insert(2, "b");
a.insert(1, "a");

let keys: Vec<_> = a.keys().cloned().collect();
assert_eq!(keys, [1, 2]);

Complexity

O(1) to create the iterator; each iteration step is O(1) amortized.

pub fn values(&self) -> Values<'_, K, V>

Gets an iterator over the values of the map, in order by key.

Examples

use wabi_tree::OSBTreeMap;

let mut a = OSBTreeMap::new();
a.insert(1, "hello");
a.insert(2, "goodbye");

let values: Vec<&str> = a.values().cloned().collect();
assert_eq!(values, ["hello", "goodbye"]);

Complexity

O(1) to create the iterator; each iteration step is O(1) amortized.

pub fn values_mut(&mut self) -> ValuesMut<'_, K, V>

Gets a mutable iterator over the values of the map, in order by key.

Examples

use wabi_tree::OSBTreeMap;

let mut a = OSBTreeMap::new();
a.insert(1, String::from("hello"));
a.insert(2, String::from("goodbye"));

for value in a.values_mut() {
    value.push_str("!");
}

let values: Vec<String> = a.values().cloned().collect();
assert_eq!(values, [String::from("hello!"),
                    String::from("goodbye!")]);

Complexity

O(1) to create the iterator; each iteration step is O(1) amortized.

pub const fn len(&self) -> usize

Returns the number of elements in the map.

Examples

use wabi_tree::OSBTreeMap;

let mut a = OSBTreeMap::new();
assert_eq!(a.len(), 0);
a.insert(1, "a");
assert_eq!(a.len(), 1);

Complexity

O(1)

pub const fn is_empty(&self) -> bool

Returns true if the map contains no elements.

Examples

use wabi_tree::OSBTreeMap;

let mut a = OSBTreeMap::new();
assert!(a.is_empty());
a.insert(1, "a");
assert!(!a.is_empty());

Complexity

O(1)

Trait Implementations

impl<K: Clone + Ord, V: Clone> Clone for OSBTreeMap<K, V>

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<K: Debug, V: Debug> Debug for OSBTreeMap<K, V>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<K, V> Default for OSBTreeMap<K, V>

fn default() -> Self

Returns the “default value” for a type.

impl<'a, K: Ord + Copy, V: Copy> Extend<(&'a K, &'a V)> for OSBTreeMap<K, V>

fn extend<T: IntoIterator<Item = (&'a K, &'a V)>>(&mut self, iter: T)

Extends a collection with the contents of an iterator.

fn extend_one(&mut self, item: A)

🔬This is a nightly-only experimental API. (extend_one)

Extends a collection with exactly one element.

fn extend_reserve(&mut self, additional: usize)

🔬This is a nightly-only experimental API. (extend_one)

Reserves capacity in a collection for the given number of additional elements.

impl<K: Ord + Clone, V> Extend<(K, V)> for OSBTreeMap<K, V>

fn extend<T: IntoIterator<Item = (K, V)>>(&mut self, iter: T)

Extends a collection with the contents of an iterator.

fn extend_one(&mut self, item: A)

🔬This is a nightly-only experimental API. (extend_one)

Extends a collection with exactly one element.

fn extend_reserve(&mut self, additional: usize)

🔬This is a nightly-only experimental API. (extend_one)

Reserves capacity in a collection for the given number of additional elements.

impl<K: Ord + Clone, V, const N: usize> From<[(K, V); N]> for OSBTreeMap<K, V>

fn from(arr: [(K, V); N]) -> Self

Converts to this type from the input type.

impl<K: Ord + Clone, V> FromIterator<(K, V)> for OSBTreeMap<K, V>

fn from_iter<T: IntoIterator<Item = (K, V)>>(iter: T) -> Self

Creates a value from an iterator.

impl<K: Hash, V: Hash> Hash for OSBTreeMap<K, V>

fn hash<H: Hasher>(&self, state: &mut H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl<K, Q, V> Index<&Q> for OSBTreeMap<K, V>

where K: Borrow<Q> + Ord + Clone, Q: ?Sized + Ord,

type Output = V

The returned type after indexing.

fn index(&self, key: &Q) -> &V

Performs the indexing (container[index]) operation.

impl<K: Clone + Ord, V> Index<Rank> for OSBTreeMap<K, V>

Indexes into the map by rank.

Panics

Panics if rank is out of bounds.

Examples

use wabi_tree::OSBTreeMap;
use wabi_tree::Rank;

let mut map = OSBTreeMap::new();
map.insert("a", 1);
map.insert("b", 2);

assert_eq!(map[Rank(0)], 1);

type Output = V

The returned type after indexing.

fn index(&self, rank: Rank) -> &Self::Output

Performs the indexing (container[index]) operation.

impl<K: Clone + Ord, V> IndexMut<Rank> for OSBTreeMap<K, V>

Mutably indexes into the map by rank.

Panics

Panics if rank is out of bounds.

Examples

use wabi_tree::OSBTreeMap;
use wabi_tree::Rank;

let mut map = OSBTreeMap::from([("a", 1), ("b", 2)]);
map[Rank(1)] = 5;

assert_eq!(map.get(&"b"), Some(&5));

fn index_mut(&mut self, rank: Rank) -> &mut Self::Output

Performs the mutable indexing (container[index]) operation.

impl<'a, K, V> IntoIterator for &'a OSBTreeMap<K, V>

type Item = (&'a K, &'a V)

The type of the elements being iterated over.

type IntoIter = Iter<'a, K, V>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Iter<'a, K, V>

Creates an iterator from a value.

impl<'a, K, V> IntoIterator for &'a mut OSBTreeMap<K, V>

type Item = (&'a K, &'a mut V)

The type of the elements being iterated over.

type IntoIter = IterMut<'a, K, V>

Which kind of iterator are we turning this into?

fn into_iter(self) -> IterMut<'a, K, V>

Creates an iterator from a value.

impl<K: Clone + Ord, V> IntoIterator for OSBTreeMap<K, V>

fn into_iter(self) -> IntoIter<K, V>

Gets an owning iterator over the entries of the map, sorted by key.

Examples

use wabi_tree::OSBTreeMap;

let map = OSBTreeMap::from([(2, "b"), (1, "a")]);
let mut iter = map.into_iter();
assert_eq!(iter.next(), Some((1, "a")));
assert_eq!(iter.next_back(), Some((2, "b")));

type Item = (K, V)

The type of the elements being iterated over.

type IntoIter = IntoIter<K, V>

Which kind of iterator are we turning this into?

impl<K: Ord, V: Ord> Ord for OSBTreeMap<K, V>

fn cmp(&self, other: &Self) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl<K: PartialEq, V: PartialEq> PartialEq for OSBTreeMap<K, V>

fn eq(&self, other: &Self) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<K: PartialOrd, V: PartialOrd> PartialOrd for OSBTreeMap<K, V>

fn partial_cmp(&self, other: &Self) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl<K: Eq, V: Eq> Eq for OSBTreeMap<K, V>