impl<K, V> BTreeMap<K, V>

const fn new() -> BTreeMap<K, V>

Makes a new, empty BTreeMap.

Does not allocate anything on its own.

Examples

use std::collections::BTreeMap;

let mut map = BTreeMap::new();

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

impl<K, V, A: Allocator + Clone> BTreeMap<K, V, A>

fn get<Q>(self: &Self, key: &Q) -> Option<&V>
where
    K: Borrow<Q> + Ord,
    Q: Ord + ?Sized

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.

Examples

use std::collections::BTreeMap;

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

fn get_key_value<Q>(self: &Self, k: &Q) -> Option<(&K, &V)>
where
    K: Borrow<Q> + Ord,
    Q: Ord + ?Sized

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 std::cmp::Ordering;
use std::collections::BTreeMap;

#[derive(Clone, Copy, Debug)]
struct S {
    id: u32,
#   #[allow(unused)] // prevents a "field `name` is never read" error
    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 = BTreeMap::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);

fn first_key_value(self: &Self) -> Option<(&K, &V)>
where
    K: Ord

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

Examples

use std::collections::BTreeMap;

let mut map = BTreeMap::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")));

fn first_entry(self: &mut Self) -> Option<OccupiedEntry<'_, K, V, A>>
where
    K: Ord

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 std::collections::BTreeMap;

let mut map = BTreeMap::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");

fn pop_first(self: &mut Self) -> Option<(K, V)>
where
    K: 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 std::collections::BTreeMap;

let mut map = BTreeMap::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());

fn last_key_value(self: &Self) -> Option<(&K, &V)>
where
    K: Ord

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

Examples

use std::collections::BTreeMap;

let mut map = BTreeMap::new();
map.insert(1, "b");
map.insert(2, "a");
assert_eq!(map.last_key_value(), Some((&2, &"a")));

fn last_entry(self: &mut Self) -> Option<OccupiedEntry<'_, K, V, A>>
where
    K: Ord

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 std::collections::BTreeMap;

let mut map = BTreeMap::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");

fn pop_last(self: &mut Self) -> Option<(K, V)>
where
    K: 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 std::collections::BTreeMap;

let mut map = BTreeMap::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());

fn contains_key<Q>(self: &Self, key: &Q) -> bool
where
    K: Borrow<Q> + Ord,
    Q: Ord + ?Sized

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 std::collections::BTreeMap;

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

fn get_mut<Q>(self: &mut Self, key: &Q) -> Option<&mut V>
where
    K: Borrow<Q> + Ord,
    Q: Ord + ?Sized

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 std::collections::BTreeMap;

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

fn insert(self: &mut Self, key: K, value: V) -> Option<V>
where
    K: 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 std::collections::BTreeMap;

let mut map = BTreeMap::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");

fn try_insert(self: &mut Self, key: K, value: V) -> Result<&mut V, OccupiedError<'_, K, V, A>>
where
    K: Ord

Tries to insert a key-value pair into the map, and returns a mutable reference to the value in the entry.

If the map already had this key present, nothing is updated, and an error containing the occupied entry and the value is returned.

Examples

#![feature(map_try_insert)]

use std::collections::BTreeMap;

let mut map = BTreeMap::new();
assert_eq!(map.try_insert(37, "a").unwrap(), &"a");

let err = map.try_insert(37, "b").unwrap_err();
assert_eq!(err.entry.key(), &37);
assert_eq!(err.entry.get(), &"a");
assert_eq!(err.value, "b");

fn remove<Q>(self: &mut Self, key: &Q) -> Option<V>
where
    K: Borrow<Q> + Ord,
    Q: Ord + ?Sized

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 std::collections::BTreeMap;

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

fn remove_entry<Q>(self: &mut Self, key: &Q) -> Option<(K, V)>
where
    K: Borrow<Q> + Ord,
    Q: Ord + ?Sized

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 std::collections::BTreeMap;

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

fn retain<F>(self: &mut Self, f: F)
where
    K: 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 std::collections::BTreeMap;

let mut map: BTreeMap<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)]));

fn append(self: &mut Self, other: &mut Self)
where
    K: Ord,
    A: Clone

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. Similar to insert, though, the key is not overwritten, which matters for types that can be == without being identical.

Examples

use std::collections::BTreeMap;

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

let mut b = BTreeMap::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"); // Note: "c" has been overwritten.
assert_eq!(a[&4], "e");
assert_eq!(a[&5], "f");

fn range<T, R>(self: &Self, range: R) -> Range<'_, K, V>
where
    T: Ord + ?Sized,
    K: Borrow<T> + Ord,
    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 std::collections::BTreeMap;
use std::ops::Bound::Included;

let mut map = BTreeMap::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());

fn range_mut<T, R>(self: &mut Self, range: R) -> RangeMut<'_, K, V>
where
    T: Ord + ?Sized,
    K: Borrow<T> + Ord,
    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 std::collections::BTreeMap;

let mut map: BTreeMap<&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}");
}

fn entry(self: &mut Self, key: K) -> Entry<'_, K, V, A>
where
    K: Ord

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

Examples

use std::collections::BTreeMap;

let mut count: BTreeMap<&str, usize> = BTreeMap::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);

fn split_off<Q: ?Sized + Ord>(self: &mut Self, key: &Q) -> Self
where
    K: Borrow<Q> + Ord,
    A: Clone

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 std::collections::BTreeMap;

let mut a = BTreeMap::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");

fn extract_if<F, R>(self: &mut Self, range: R, pred: F) -> ExtractIf<'_, K, V, R, F, A>
where
    K: 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 extract_if().for_each(drop) if you do not need the returned iterator, or retain with a negated predicate if you also do not need to restrict the range.

Examples

use std::collections::BTreeMap;

// Splitting a map into even and odd keys, reusing the original map:
let mut map: BTreeMap<i32, i32> = (0..8).map(|x| (x, x)).collect();
let evens: BTreeMap<_, _> = 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: BTreeMap<i32, i32> = (0..8).map(|x| (x, x)).collect();
let low: BTreeMap<_, _> = 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]);

fn into_keys(self: Self) -> IntoKeys<K, V, A>

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 std::collections::BTreeMap;

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

let keys: Vec<i32> = a.into_keys().collect();
assert_eq!(keys, [1, 2]);

fn into_values(self: Self) -> IntoValues<K, V, A>

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 std::collections::BTreeMap;

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

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

impl<K, V, A: Allocator + Clone> BTreeMap<K, V, A>

fn clear(self: &mut Self)

Clears the map, removing all elements.

Examples

use std::collections::BTreeMap;

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

const fn new_in(alloc: A) -> BTreeMap<K, V, A>

Makes a new empty BTreeMap with a reasonable choice for B.

Examples

# #![feature(allocator_api)]
# #![feature(btreemap_alloc)]
use std::collections::BTreeMap;
use std::alloc::Global;

let mut map = BTreeMap::new_in(Global);

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

impl<K, V, A: Allocator + Clone> BTreeMap<K, V, A>

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

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

Examples

use std::collections::BTreeMap;

let mut map = BTreeMap::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"));

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

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

Examples

use std::collections::BTreeMap;

let mut map = BTreeMap::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;
    }
}

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

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

Examples

use std::collections::BTreeMap;

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

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

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

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

Examples

use std::collections::BTreeMap;

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

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

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

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

Examples

use std::collections::BTreeMap;

let mut a = BTreeMap::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!")]);

const fn len(self: &Self) -> usize

Returns the number of elements in the map.

Examples

use std::collections::BTreeMap;

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

const fn is_empty(self: &Self) -> bool

Returns true if the map contains no elements.

Examples

use std::collections::BTreeMap;

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

fn lower_bound<Q>(self: &Self, bound: Bound<&Q>) -> Cursor<'_, K, V>
where
    K: Borrow<Q> + Ord,
    Q: Ord + ?Sized

Returns a Cursor pointing at the gap before the smallest key greater than the given bound.

Passing Bound::Included(x) will return a cursor pointing to the gap before the smallest key greater than or equal to x.

Passing Bound::Excluded(x) will return a cursor pointing to the gap before the smallest key greater than x.

Passing Bound::Unbounded will return a cursor pointing to the gap before the smallest key in the map.

Examples

#![feature(btree_cursors)]

use std::collections::BTreeMap;
use std::ops::Bound;

let map = BTreeMap::from([
    (1, "a"),
    (2, "b"),
    (3, "c"),
    (4, "d"),
]);

let cursor = map.lower_bound(Bound::Included(&2));
assert_eq!(cursor.peek_prev(), Some((&1, &"a")));
assert_eq!(cursor.peek_next(), Some((&2, &"b")));

let cursor = map.lower_bound(Bound::Excluded(&2));
assert_eq!(cursor.peek_prev(), Some((&2, &"b")));
assert_eq!(cursor.peek_next(), Some((&3, &"c")));

let cursor = map.lower_bound(Bound::Unbounded);
assert_eq!(cursor.peek_prev(), None);
assert_eq!(cursor.peek_next(), Some((&1, &"a")));

fn lower_bound_mut<Q>(self: &mut Self, bound: Bound<&Q>) -> CursorMut<'_, K, V, A>
where
    K: Borrow<Q> + Ord,
    Q: Ord + ?Sized

Returns a CursorMut pointing at the gap before the smallest key greater than the given bound.

Passing Bound::Included(x) will return a cursor pointing to the gap before the smallest key greater than or equal to x.

Passing Bound::Excluded(x) will return a cursor pointing to the gap before the smallest key greater than x.

Passing Bound::Unbounded will return a cursor pointing to the gap before the smallest key in the map.

Examples

#![feature(btree_cursors)]

use std::collections::BTreeMap;
use std::ops::Bound;

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

let mut cursor = map.lower_bound_mut(Bound::Included(&2));
assert_eq!(cursor.peek_prev(), Some((&1, &mut "a")));
assert_eq!(cursor.peek_next(), Some((&2, &mut "b")));

let mut cursor = map.lower_bound_mut(Bound::Excluded(&2));
assert_eq!(cursor.peek_prev(), Some((&2, &mut "b")));
assert_eq!(cursor.peek_next(), Some((&3, &mut "c")));

let mut cursor = map.lower_bound_mut(Bound::Unbounded);
assert_eq!(cursor.peek_prev(), None);
assert_eq!(cursor.peek_next(), Some((&1, &mut "a")));

fn upper_bound<Q>(self: &Self, bound: Bound<&Q>) -> Cursor<'_, K, V>
where
    K: Borrow<Q> + Ord,
    Q: Ord + ?Sized

Returns a Cursor pointing at the gap after the greatest key smaller than the given bound.

Passing Bound::Included(x) will return a cursor pointing to the gap after the greatest key smaller than or equal to x.

Passing Bound::Excluded(x) will return a cursor pointing to the gap after the greatest key smaller than x.

Passing Bound::Unbounded will return a cursor pointing to the gap after the greatest key in the map.

Examples

#![feature(btree_cursors)]

use std::collections::BTreeMap;
use std::ops::Bound;

let map = BTreeMap::from([
    (1, "a"),
    (2, "b"),
    (3, "c"),
    (4, "d"),
]);

let cursor = map.upper_bound(Bound::Included(&3));
assert_eq!(cursor.peek_prev(), Some((&3, &"c")));
assert_eq!(cursor.peek_next(), Some((&4, &"d")));

let cursor = map.upper_bound(Bound::Excluded(&3));
assert_eq!(cursor.peek_prev(), Some((&2, &"b")));
assert_eq!(cursor.peek_next(), Some((&3, &"c")));

let cursor = map.upper_bound(Bound::Unbounded);
assert_eq!(cursor.peek_prev(), Some((&4, &"d")));
assert_eq!(cursor.peek_next(), None);

fn upper_bound_mut<Q>(self: &mut Self, bound: Bound<&Q>) -> CursorMut<'_, K, V, A>
where
    K: Borrow<Q> + Ord,
    Q: Ord + ?Sized

Returns a CursorMut pointing at the gap after the greatest key smaller than the given bound.

Passing Bound::Included(x) will return a cursor pointing to the gap after the greatest key smaller than or equal to x.

Passing Bound::Excluded(x) will return a cursor pointing to the gap after the greatest key smaller than x.

Passing Bound::Unbounded will return a cursor pointing to the gap after the greatest key in the map.

Examples

#![feature(btree_cursors)]

use std::collections::BTreeMap;
use std::ops::Bound;

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

let mut cursor = map.upper_bound_mut(Bound::Included(&3));
assert_eq!(cursor.peek_prev(), Some((&3, &mut "c")));
assert_eq!(cursor.peek_next(), Some((&4, &mut "d")));

let mut cursor = map.upper_bound_mut(Bound::Excluded(&3));
assert_eq!(cursor.peek_prev(), Some((&2, &mut "b")));
assert_eq!(cursor.peek_next(), Some((&3, &mut "c")));

let mut cursor = map.upper_bound_mut(Bound::Unbounded);
assert_eq!(cursor.peek_prev(), Some((&4, &mut "d")));
assert_eq!(cursor.peek_next(), None);

impl<'a, K: Ord + Copy, V: Copy, A: Allocator + Clone> Extend for BTreeMap<K, V, A>

fn extend<I: IntoIterator<Item = (&'a K, &'a V)>>(self: &mut Self, iter: I)

fn extend_one(self: &mut Self, (k, v): (&'a K, &'a V))

impl<K, Q, V, A: Allocator + Clone> Index for BTreeMap<K, V, A>

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

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

Panics

Panics if the key is not present in the BTreeMap.

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

fn default() -> BTreeMap<K, V>

Creates an empty BTreeMap.

impl<K, V, A> Freeze for BTreeMap<K, V, A>

impl<K, V, A> RefUnwindSafe for BTreeMap<K, V, A>

impl<K, V, A> Send for BTreeMap<K, V, A>

impl<K, V, A> Sync for BTreeMap<K, V, A>

impl<K, V, A> Unpin for BTreeMap<K, V, A>

impl<K, V, A> UnwindSafe for BTreeMap<K, V, A>

impl<K, V, A: Allocator + Clone> Drop for BTreeMap<K, V, A>

fn drop(self: &mut Self)

impl<K, V, A: Allocator + Clone> IntoIterator for BTreeMap<K, V, A>

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

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

impl<K: Clone, V: Clone, A: Allocator + Clone> Clone for BTreeMap<K, V, A>

fn clone(self: &Self) -> BTreeMap<K, V, A>

impl<K: Debug, V: Debug, A: Allocator + Clone> Debug for BTreeMap<K, V, A>

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

impl<K: Eq, V: Eq, A: Allocator + Clone> Eq for BTreeMap<K, V, A>

impl<K: Hash, V: Hash, A: Allocator + Clone> Hash for BTreeMap<K, V, A>

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

impl<K: Ord, V> FromIterator for BTreeMap<K, V>

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

Constructs a BTreeMap<K, V> from an iterator of key-value pairs.

If the iterator produces any pairs with equal keys, all but one of the corresponding values will be dropped.

impl<K: Ord, V, A: Allocator + Clone> Extend for BTreeMap<K, V, A>

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

fn extend_one(self: &mut Self, (k, v): (K, V))

impl<K: Ord, V, N: usize> From for BTreeMap<K, V>

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

Converts a [(K, V); N] into a BTreeMap<K, V>.

If any entries in the array have equal keys, all but one of the corresponding values will be dropped.

use std::collections::BTreeMap;

let map1 = BTreeMap::from([(1, 2), (3, 4)]);
let map2: BTreeMap<_, _> = [(1, 2), (3, 4)].into();
assert_eq!(map1, map2);

impl<K: Ord, V: Ord, A: Allocator + Clone> Ord for BTreeMap<K, V, A>

fn cmp(self: &Self, other: &BTreeMap<K, V, A>) -> Ordering

impl<K: PartialEq, V: PartialEq, A: Allocator + Clone> PartialEq for BTreeMap<K, V, A>

fn eq(self: &Self, other: &BTreeMap<K, V, A>) -> bool

impl<K: PartialOrd, V: PartialOrd, A: Allocator + Clone> PartialOrd for BTreeMap<K, V, A>

fn partial_cmp(self: &Self, other: &BTreeMap<K, V, A>) -> Option<Ordering>

impl<T> Any for BTreeMap<K, V, A>

fn type_id(self: &Self) -> TypeId

impl<T> Borrow for BTreeMap<K, V, A>

fn borrow(self: &Self) -> &T

impl<T> BorrowMut for BTreeMap<K, V, A>

fn borrow_mut(self: &mut Self) -> &mut T

impl<T> CloneToUninit for BTreeMap<K, V, A>

unsafe fn clone_to_uninit(self: &Self, dest: *mut u8)

impl<T> From for BTreeMap<K, V, A>

fn from(t: T) -> T

Returns the argument unchanged.

impl<T> ToOwned for BTreeMap<K, V, A>

fn to_owned(self: &Self) -> T

fn clone_into(self: &Self, target: &mut T)

impl<T, U> Into for BTreeMap<K, V, A>

fn into(self: Self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of [From]<T> for U chooses to do.

impl<T, U> TryFrom for BTreeMap<K, V, A>

fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

impl<T, U> TryInto for BTreeMap<K, V, A>

fn try_into(self: Self) -> Result<U, <U as TryFrom<T>>::Error>