Struct BTreeMap

pub struct BTreeMap<K, V, A = Global>
where
    A: Allocator + Clone,
{ /* private fields */ }

Available on crate feature std only.

An ordered map based on a B-Tree.

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 amount 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 single comparison should be a cache-miss. Since these are both notably expensive things to do 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.

Currently, our implementation simply performs naive linear search. This provides excellent performance on small nodes of elements which are cheap to compare. However in the future we would like to further explore choosing the optimal search strategy based on the choice of B, and possibly other factors. Using linear search, searching for a random element is expected to take B * log(n) comparisons, which is generally worse than a BST. In practice, however, performance is excellent.

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 BTreeMap that observed the logic error and not result in undefined behavior. This could include panics, incorrect results, aborts, memory leaks, and non-termination.

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

Examples

use std::collections::BTreeMap;

// type inference lets us omit an explicit type signature (which
// would be `BTreeMap<&str, &str>` in this example).
let mut movie_reviews = BTreeMap::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 Misérables") {
    println!("We've got {} reviews, but Les Misérables 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}\"");
}

A BTreeMap with a known list of items can be initialized from an array:

use std::collections::BTreeMap;

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

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

use std::collections::BTreeMap;

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

Implementations

impl<K, A> BTreeMap<K, SetValZST, A>

where A: Allocator + Clone,

Internal functionality for BTreeSet.

This impl block contains no items.

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

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

Available on crate feature alloc only.

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> BTreeMap<K, V, A>

where A: Allocator + Clone,

pub fn clear(&mut self)

Available on crate feature alloc only.

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());

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

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

Available on crate feature alloc only.

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

Examples

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> BTreeMap<K, V, A>

where A: Allocator + Clone,

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

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

Available on crate feature alloc only.

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);

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

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

Available on crate feature alloc only.

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,
    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);

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

where K: Ord,

Available on crate feature alloc only.

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")));

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

where K: Ord,

Available on crate feature alloc only.

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");

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

where K: Ord,

Available on crate feature alloc only.

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());

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

where K: Ord,

Available on crate feature alloc only.

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")));

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

where K: Ord,

Available on crate feature alloc only.

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");

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

where K: Ord,

Available on crate feature alloc only.

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());

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

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

Available on crate feature alloc only.

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);

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

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

Available on crate feature alloc only.

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");

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

where K: Ord,

Available on crate feature alloc only.

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");

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

where K: Ord,

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

Available on crate feature alloc only.

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");

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

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

Available on crate feature alloc only.

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);

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

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

Available on crate feature alloc only.

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);

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

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

Available on crate feature alloc only.

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)]));

pub fn append(&mut self, other: &mut BTreeMap<K, V, A>)

where K: Ord, A: Clone,

Available on crate feature alloc only.

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 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");

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

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

Available on crate feature alloc only.

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());

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

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

Available on crate feature alloc only.

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}");
}

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

where K: Ord,

Available on crate feature alloc only.

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);

pub fn split_off<Q>(&mut self, key: &Q) -> BTreeMap<K, V, A>

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

Available on crate feature alloc only.

Splits the collection into two at the given key. Returns everything after the given key, including the key.

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");

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

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

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

Available on crate feature alloc only.

Creates an iterator that visits all elements (key-value pairs) 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

Splitting a map into even and odd keys, reusing the original map:

#![feature(btree_extract_if)]
use std::collections::BTreeMap;

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]);

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

Available on crate feature alloc only.

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]);

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

Available on crate feature alloc only.

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> BTreeMap<K, V, A>

where A: Allocator + Clone,

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

Available on crate feature alloc only.

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"));

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

Available on crate feature alloc only.

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;
    }
}

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

Available on crate feature alloc only.

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]);

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

Available on crate feature alloc only.

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"]);

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

Available on crate feature alloc only.

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!")]);

pub fn len(&self) -> usize

Available on crate feature alloc only.

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);

pub fn is_empty(&self) -> bool

Available on crate feature alloc only.

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());

pub fn lower_bound<Q>(&self, bound: Bound<&Q>) -> Cursor<'_, K, V>

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

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

Available on crate feature alloc only.

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")));

pub fn lower_bound_mut<Q>(&mut self, bound: Bound<&Q>) -> CursorMut<'_, K, V, A>

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

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

Available on crate feature alloc only.

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")));

pub fn upper_bound<Q>(&self, bound: Bound<&Q>) -> Cursor<'_, K, V>

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

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

Available on crate feature alloc only.

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);

pub fn upper_bound_mut<Q>(&mut self, bound: Bound<&Q>) -> CursorMut<'_, K, V, A>

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

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

Available on crate feature alloc only.

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);

Trait Implementations

impl<K, V> Accumulate<(K, V)> for BTreeMap<K, V>

where K: Ord,

fn initial(_capacity: Option<usize>) -> BTreeMap<K, V>

Create a new Extend of the correct type

fn accumulate(&mut self, _: (K, V))

Accumulate the input into an accumulator

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

where K: Archive + Ord, V: Archive, <K as Archive>::Archived: Ord,

type Archived = ArchivedBTreeMap<<K as Archive>::Archived, <V as Archive>::Archived>

The archived representation of this type.

type Resolver = BTreeMapResolver

The resolver for this type. It must contain all the additional information from serializing needed to make the archived type from the normal type.

fn resolve( &self, resolver: <BTreeMap<K, V> as Archive>::Resolver, out: Place<<BTreeMap<K, V> as Archive>::Archived>, )

Creates the archived version of this value at the given position and writes it to the given output.

const COPY_OPTIMIZATION: CopyOptimization<Self> = _

An optimization flag that allows the bytes of this type to be copied directly to a writer instead of calling serialize.

impl<K, V> ArchiveWith<BTreeMap<K, V>> for AsVec

where K: Archive, V: Archive,

type Archived = ArchivedVec<Entry<<K as Archive>::Archived, <V as Archive>::Archived>>

The archived type of Self with F.

type Resolver = VecResolver

The resolver of a Self with F.

fn resolve_with( field: &BTreeMap<K, V>, resolver: <AsVec as ArchiveWith<BTreeMap<K, V>>>::Resolver, out: Place<<AsVec as ArchiveWith<BTreeMap<K, V>>>::Archived>, )

Resolves the archived type using a reference to the field type F.

impl<A, B, K, V> ArchiveWith<BTreeMap<K, V>> for MapKV<A, B>

where A: ArchiveWith<K>, B: ArchiveWith<V>,

type Archived = ArchivedBTreeMap<<A as ArchiveWith<K>>::Archived, <B as ArchiveWith<V>>::Archived>

The archived type of Self with F.

type Resolver = BTreeMapResolver

The resolver of a Self with F.

fn resolve_with( field: &BTreeMap<K, V>, resolver: <MapKV<A, B> as ArchiveWith<BTreeMap<K, V>>>::Resolver, out: Place<<MapKV<A, B> as ArchiveWith<BTreeMap<K, V>>>::Archived>, )

Resolves the archived type using a reference to the field type F.

impl<K, V> BitSized<{$PTR_BITS * 3}> for BTreeMap<K, V>

const BIT_SIZE: usize = _

The bit size of this type (only the relevant data part, without padding).

const MIN_BYTE_SIZE: usize = _

The rounded up byte size for this type.

fn bit_size(&self) -> usize

Returns the bit size of this type (only the relevant data part, without padding).

fn min_byte_size(&self) -> usize

Returns the rounded up byte size for this type.

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

where K: Clone, V: Clone, A: Allocator + Clone,

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

Returns a copy of the value.

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

Performs copy-assignment from source.

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

const DEFAULT: Self

Returns the compile-time “default value” for a type.

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

fn collection_capacity(&self) -> Result<usize, NotAvailable>

Returns [NotSupported][E::NotSupported].

fn collection_is_full(&self) -> Result<bool, NotAvailable>

Returns [NotSupported][E::NotSupported].

type Element = V

The element type of the collection.

fn collection_len(&self) -> Result<usize, NotAvailable>

Returns the current number of elements in the collection.

fn collection_is_empty(&self) -> Result<bool, NotAvailable>

Returns true if the collection is empty, false if it’s not.

fn collection_contains( &self, element: Self::Element, ) -> Result<bool, NotAvailable>

where V: PartialEq,

Returns true if the collection contains the given element.

fn collection_count( &self, element: &Self::Element, ) -> Result<usize, NotAvailable>

where V: PartialEq,

Counts the number of times a given element appears in the collection.

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

where K: Debug, V: Debug, A: Allocator + Clone,

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

Formats the value using the given formatter.

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

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

Creates an empty BTreeMap.

impl<'de, K, V> Deserialize<'de> for BTreeMap<K, V>

where K: Deserialize<'de> + Ord, V: Deserialize<'de>,

fn deserialize<D>( deserializer: D, ) -> Result<BTreeMap<K, V>, <D as Deserializer<'de>>::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<K, V, D> Deserialize<BTreeMap<K, V>, D> for ArchivedBTreeMap<<K as Archive>::Archived, <V as Archive>::Archived>

where K: Archive + Ord, <K as Archive>::Archived: Deserialize<K, D> + Ord, V: Archive, <V as Archive>::Archived: Deserialize<V, D>, D: Fallible + ?Sized,

fn deserialize( &self, deserializer: &mut D, ) -> Result<BTreeMap<K, V>, <D as Fallible>::Error>

Deserializes using the given deserializer

impl<A, B, K, V, D> DeserializeWith<ArchivedBTreeMap<<A as ArchiveWith<K>>::Archived, <B as ArchiveWith<V>>::Archived>, BTreeMap<K, V>, D> for MapKV<A, B>

where A: ArchiveWith<K> + DeserializeWith<<A as ArchiveWith<K>>::Archived, K, D>, B: ArchiveWith<V> + DeserializeWith<<B as ArchiveWith<V>>::Archived, V, D>, K: Ord, D: Fallible + ?Sized,

fn deserialize_with( field: &ArchivedBTreeMap<<A as ArchiveWith<K>>::Archived, <B as ArchiveWith<V>>::Archived>, deserializer: &mut D, ) -> Result<BTreeMap<K, V>, <D as Fallible>::Error>

Deserializes the field type F using the given deserializer.

impl<K, V, D> DeserializeWith<ArchivedVec<Entry<<K as Archive>::Archived, <V as Archive>::Archived>>, BTreeMap<K, V>, D> for AsVec

where K: Archive + Ord, V: Archive, <K as Archive>::Archived: Deserialize<K, D>, <V as Archive>::Archived: Deserialize<V, D>, D: Fallible + ?Sized,

fn deserialize_with( field: &ArchivedVec<Entry<<K as Archive>::Archived, <V as Archive>::Archived>>, deserializer: &mut D, ) -> Result<BTreeMap<K, V>, <D as Fallible>::Error>

Deserializes the field type F using the given deserializer.

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

where A: Allocator + Clone,

fn drop(&mut self)

Executes the destructor for this type.

impl<'a, K, V, A> Extend<(&'a K, &'a V)> for BTreeMap<K, V, A>

where K: Ord + Copy, V: Copy, A: Allocator + Clone,

fn extend<I>(&mut self, iter: I)

where I: IntoIterator<Item = (&'a K, &'a V)>,

Extends a collection with the contents of an iterator.

fn extend_one(&mut self, _: (&'a K, &'a V))

🔬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, V, A> Extend<(K, V)> for BTreeMap<K, V, A>

where K: Ord, A: Allocator + Clone,

fn extend<T>(&mut self, iter: T)

where T: IntoIterator<Item = (K, V)>,

Extends a collection with the contents of an iterator.

fn extend_one(&mut self, _: (K, V))

🔬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, V, const N: usize> From<[(K, V); N]> for BTreeMap<K, V>

where K: Ord,

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

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, V> FromIterator<(K, V)> for BTreeMap<K, V>

where K: Ord,

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

where T: IntoIterator<Item = (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, V> FromParallelIterator<(K, V)> for BTreeMap<K, V>

where K: Ord + Send, V: Send,

Collects (key, value) pairs from a parallel iterator into a btreemap. If multiple pairs correspond to the same key, then the ones produced earlier in the parallel iterator will be overwritten, just as with a sequential iterator.

fn from_par_iter<I>(par_iter: I) -> BTreeMap<K, V>

where I: IntoParallelIterator<Item = (K, V)>,

Creates an instance of the collection from the parallel iterator par_iter.

impl<'py, K, V> FromPyObject<'py> for BTreeMap<K, V>

where K: FromPyObject<'py> + Ord, V: FromPyObject<'py>,

fn extract_bound(ob: &Bound<'py, PyAny>) -> Result<BTreeMap<K, V>, PyErr>

Extracts Self from the bound smart pointer obj.

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

where K: Hash, V: Hash, A: Allocator + Clone,

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

where H: Hasher,

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, A> Index<&Q> for BTreeMap<K, V, A>

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

fn index(&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.

type Output = V

The returned type after indexing.

impl<'de, K, V, E> IntoDeserializer<'de, E> for BTreeMap<K, V>

where K: IntoDeserializer<'de, E> + Eq + Ord, V: IntoDeserializer<'de, E>, E: Error,

type Deserializer = MapDeserializer<'de, <BTreeMap<K, V> as IntoIterator>::IntoIter, E>

The type of the deserializer being converted into.

fn into_deserializer( self, ) -> <BTreeMap<K, V> as IntoDeserializer<'de, E>>::Deserializer

Convert this value into a deserializer.

impl<'a, K, V, A> IntoIterator for &'a BTreeMap<K, V, A>

where A: Allocator + Clone,

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, A> IntoIterator for &'a mut BTreeMap<K, V, A>

where A: Allocator + Clone,

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, V, A> IntoIterator for BTreeMap<K, V, A>

where A: Allocator + Clone,

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

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

type Item = (K, V)

The type of the elements being iterated over.

type IntoIter = IntoIter<K, V, A>

Which kind of iterator are we turning this into?

impl<'a, K, V> IntoParallelIterator for &'a BTreeMap<K, V>

where K: Ord + Sync, V: Sync,

type Item = <&'a BTreeMap<K, V> as IntoIterator>::Item

The type of item that the parallel iterator will produce.

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

The parallel iterator type that will be created.

fn into_par_iter(self) -> <&'a BTreeMap<K, V> as IntoParallelIterator>::Iter

Converts self into a parallel iterator.

impl<'a, K, V> IntoParallelIterator for &'a mut BTreeMap<K, V>

where K: Ord + Sync, V: Send,

type Item = <&'a mut BTreeMap<K, V> as IntoIterator>::Item

The type of item that the parallel iterator will produce.

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

The parallel iterator type that will be created.

fn into_par_iter(self) -> <&'a mut BTreeMap<K, V> as IntoParallelIterator>::Iter

Converts self into a parallel iterator.

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

where K: Ord + Send, V: Send,

type Item = <BTreeMap<K, V> as IntoIterator>::Item

The type of item that the parallel iterator will produce.

type Iter = IntoIter<K, V>

The parallel iterator type that will be created.

fn into_par_iter(self) -> <BTreeMap<K, V> as IntoParallelIterator>::Iter

Converts self into a parallel iterator.

impl<K, V> IntoPy<Py<PyAny>> for BTreeMap<K, V>

where K: Eq + IntoPy<Py<PyAny>>, V: IntoPy<Py<PyAny>>,

fn into_py(self, py: Python<'_>) -> Py<PyAny>

👎Deprecated since 0.23.0: IntoPy is going to be replaced by IntoPyObject. See the migration guide (https://pyo3.rs/v0.23.0/migration) for more information.

Performs the conversion.

impl<'a, 'py, K, V> IntoPyObject<'py> for &'a BTreeMap<K, V>

where &'a K: IntoPyObject<'py> + Eq, &'a V: IntoPyObject<'py>, K: 'a, V: 'a,

type Target = PyDict

The Python output type

type Output = Bound<'py, <&'a BTreeMap<K, V> as IntoPyObject<'py>>::Target>

The smart pointer type to use.

type Error = PyErr

The type returned in the event of a conversion error.

fn into_pyobject( self, py: Python<'py>, ) -> Result<<&'a BTreeMap<K, V> as IntoPyObject<'py>>::Output, <&'a BTreeMap<K, V> as IntoPyObject<'py>>::Error>

Performs the conversion.

impl<'py, K, V> IntoPyObject<'py> for BTreeMap<K, V>

where K: IntoPyObject<'py> + Eq, V: IntoPyObject<'py>,

type Target = PyDict

The Python output type

type Output = Bound<'py, <BTreeMap<K, V> as IntoPyObject<'py>>::Target>

The smart pointer type to use.

type Error = PyErr

The type returned in the event of a conversion error.

fn into_pyobject( self, py: Python<'py>, ) -> Result<<BTreeMap<K, V> as IntoPyObject<'py>>::Output, <BTreeMap<K, V> as IntoPyObject<'py>>::Error>

Performs the conversion.

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

where K: Ord, V: Ord, A: Allocator + Clone,

fn cmp(&self, other: &BTreeMap<K, V, A>) -> 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<'a, K, V> ParallelExtend<(&'a K, &'a V)> for BTreeMap<K, V>

where K: 'a + Copy + Ord + Send + Sync, V: 'a + Copy + Send + Sync,

Extends a B-tree map with copied items from a parallel iterator.

fn par_extend<I>(&mut self, par_iter: I)

where I: IntoParallelIterator<Item = (&'a K, &'a V)>,

Extends an instance of the collection with the elements drawn from the parallel iterator par_iter.

impl<K, V> ParallelExtend<(K, V)> for BTreeMap<K, V>

where K: Ord + Send, V: Send,

Extends a B-tree map with items from a parallel iterator.

fn par_extend<I>(&mut self, par_iter: I)

where I: IntoParallelIterator<Item = (K, V)>,

Extends an instance of the collection with the elements drawn from the parallel iterator par_iter.

impl<K, V, AK, AV> PartialEq<BTreeMap<K, V>> for ArchivedBTreeMap<AK, AV>

where AK: PartialEq<K>, AV: PartialEq<V>,

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

where K: PartialEq, V: PartialEq, A: Allocator + Clone,

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

where K: PartialOrd, V: PartialOrd, A: Allocator + Clone,

fn partial_cmp(&self, other: &BTreeMap<K, V, A>) -> 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, V, S> Serialize<S> for BTreeMap<K, V>

where K: Serialize<S> + Ord, <K as Archive>::Archived: Ord, V: Serialize<S>, S: Allocator + Fallible + Writer + ?Sized, <S as Fallible>::Error: Source,

fn serialize( &self, serializer: &mut S, ) -> Result<<BTreeMap<K, V> as Archive>::Resolver, <S as Fallible>::Error>

Writes the dependencies for the object and returns a resolver that can create the archived type.

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

where K: Serialize, V: Serialize,

fn serialize<S>( &self, serializer: S, ) -> Result<<S as Serializer>::Ok, <S as Serializer>::Error>

where S: Serializer,

Serialize this value into the given Serde serializer.

impl<K, V, S> SerializeWith<BTreeMap<K, V>, S> for AsVec

where K: Serialize<S>, V: Serialize<S>, S: Fallible + Allocator + Writer + ?Sized,

fn serialize_with( field: &BTreeMap<K, V>, serializer: &mut S, ) -> Result<<AsVec as ArchiveWith<BTreeMap<K, V>>>::Resolver, <S as Fallible>::Error>

Serializes the field type F using the given serializer.

impl<A, B, K, V, S> SerializeWith<BTreeMap<K, V>, S> for MapKV<A, B>

where A: ArchiveWith<K> + SerializeWith<K, S>, B: ArchiveWith<V> + SerializeWith<V, S>, <A as ArchiveWith<K>>::Archived: Ord, S: Fallible + Allocator + Writer + ?Sized, <S as Fallible>::Error: Source,

fn serialize_with( field: &BTreeMap<K, V>, serializer: &mut S, ) -> Result<<MapKV<A, B> as ArchiveWith<BTreeMap<K, V>>>::Resolver, <S as Fallible>::Error>

Serializes the field type F using the given serializer.

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

where K: Eq + ToPyObject, V: ToPyObject,

fn to_object(&self, py: Python<'_>) -> Py<PyAny>

👎Deprecated since 0.23.0: ToPyObject is going to be replaced by IntoPyObject. See the migration guide (https://pyo3.rs/v0.23.0/migration) for more information.

Converts self into a Python object.

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

where K: Eq, V: Eq, A: Allocator + Clone,

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

where A: Allocator + Clone + UnwindSafe, K: RefUnwindSafe, V: RefUnwindSafe,