Struct BTreeMap 

pub struct BTreeMap<K, V>
where
    K: Ord,
{ /* private fields */ }

An ordered map based on a two-level 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.

However, B-Trees are not as performant as they could be, since there still is a significant amount of pointer indirection, and, in Rust’s case, a linear search on the node level.

Our implementation restricts a B-Tree to only have two levels, and have zero pointer indirection, with data residing only in the second level. The first level is an array, sorted by each node’s maximum element. The second is where all the data is at, being a sorted array of sorted arrays of fixed size, 1024. Lookups are done in two steps, one binary search over the first level, and one over the second. This is significantly simpler than a regular B-Tree. The main tradeoff, is that insertion and deletion relies on always having to sort an array of size 1024. In practice, this is barely noticable, but still presents itself as a drawback significant enough to warrant considering not using this crate. Please, read the Readme in order to see benchmarking results.

Furthermore, it has a very efficient get-the-ith-element implementation, that is thousands(literally) of times faster than what is currently available in stdlib.

Iterators obtained from functions such as BTreeMap::iter, BTreeMap::values, or BTreeMap::keys produce their items in order by key, and directly leverage Rust’s own slice iterators, therefore being as fast as possible.

Examples

use wt_indexset::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 wt_indexset::BTreeMap;

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

Implementations

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

where K: Ord,

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

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 wt_indexset::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 clear(&mut self)

Clears the map, removing all elements.

Examples

Basic usage:

use wt_indexset::BTreeMap;

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

pub fn contains_key<Q>(&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

Basic usage:

use wt_indexset::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 first_key_value(&self) -> Option<(&K, &V)>

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

Examples

Basic usage:

use wt_indexset::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 get<Q>(&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

Basic usage:

use wt_indexset::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_index(&self, idx: usize) -> Option<(&K, &V)>

Returns the key-value pair currently residing at the given position.

Examples

use wt_indexset::BTreeMap;

let mut map = BTreeMap::new();
map.insert(1, "a");
assert_eq!(map.get_index(0), Some((&1, &"a")));
assert_eq!(map.get_index(1), None);

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

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

Returns the key-value pair corresponding to the supplied key.

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 wt_indexset::BTreeMap;

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

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

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

Basic usage:

use wt_indexset::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 get_mut_index(&mut self, index: usize) -> Option<&mut V>

Returns a mutable reference to the value at the designated index

Examples

Basic usage:

use wt_indexset::BTreeMap;

let mut map = BTreeMap::new();
map.insert(1, "a");
if let Some(x) = map.get_mut_index(0) {
    *x = "b";
}
assert_eq!(map[&1], "b");

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

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

Basic usage:

use wt_indexset::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 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 wt_indexset::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>

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 wt_indexset::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"]);

pub fn is_empty(&self) -> bool

Returns true if the map contains no elements.

Examples

Basic usage:

use wt_indexset::BTreeMap;

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

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

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

Examples

Basic usage:

use wt_indexset::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>

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

Examples

Basic usage:

use wt_indexset::BTreeMap;

let mut map = BTreeMap::from_iter([
   ("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>

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

Examples

Basic usage:

use wt_indexset::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 last_key_value(&self) -> Option<(&K, &V)>

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

Examples

Basic usage:

use wt_indexset::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 len(&self) -> usize

Returns the number of elements in the map.

Examples

Basic usage:

use wt_indexset::BTreeMap;

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

pub fn new() -> Self

Makes a new, empty BTreeMap.

Allocates a vec of capacity 1024.

Examples

Basic usage:

use wt_indexset::BTreeMap;

let mut map = BTreeMap::new();

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

pub fn with_maximum_node_size(maximum_node_size: usize) -> Self

Makes a new, empty BTreeSet with the given maximum node size. Allocates one vec with the capacity set to be the specified node size.

Examples

use wt_indexset::BTreeMap;

let mut set: BTreeMap<usize, usize> = BTreeMap::with_maximum_node_size(128);

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

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 wt_indexset::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 pop_index(&mut self, index: usize) -> (K, V)

Removes the i-th element from the map and returns it, if any.

Examples

use wt_indexset::BTreeMap;

let mut map = BTreeMap::new();

map.insert(1,"a");
map.insert(2, "b");
assert_eq!(map.pop_index(0), (1, "a"));
assert_eq!(map.pop_index(0), (2, "b"));
assert!(map.is_empty());

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

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 wt_indexset::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 range<Q, R>(&self, range: R) -> RangeMap<'_, K, V>

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

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

Basic usage:

use wt_indexset::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_idx<R>(&self, range: R) -> RangeMap<'_, K, V>

where R: RangeBounds<usize>,

pub fn range_mut<Q, R>(&mut self, range: R) -> RangeMut<'_, K, V>

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

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

Basic usage:

use wt_indexset::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 range_mut_idx<R>(&mut self, range: R) -> RangeMut<'_, K, V>

where R: RangeBounds<usize>,

pub fn remove<Q>(&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

Basic usage:

use wt_indexset::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,

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

Basic usage:

use wt_indexset::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, Q>(&mut self, f: F)

where K: Borrow<Q> + Ord, Q: Ord, F: FnMut(&Q, &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 wt_indexset::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 split_off<Q>(&mut self, key: &Q) -> Self

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

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

Examples

Basic usage:

use wt_indexset::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 values(&self) -> Values<'_, K, V>

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

Examples

Basic usage:

use wt_indexset::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>

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

Examples

Basic usage:

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

where K: Ord,

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

Examples

Basic usage:

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

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");

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

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");

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

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

Returns a Cursor pointing at the first element that is above the given bound.

If no such element exists then a cursor pointing at the “ghost” non-element is returned.

Passing Bound::Unbounded will return a cursor pointing at the first element of the map.

Examples

Basic usage:

use wt_indexset::BTreeMap;
use std::ops::Bound;

let mut a = BTreeMap::new();
a.insert(1, "a");
a.insert(2, "b");
a.insert(3, "c");
a.insert(4, "c");
let cursor = a.lower_bound(Bound::Excluded(&2));
assert_eq!(cursor.key(), Some(&3));

pub fn rank<Q>(&self, value: &Q) -> usize

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

Returns the position in which the given element would fall in the already-existing sorted order.

The value may be any borrowed form of the set’s element type, but the ordering on the borrowed form must match the ordering on the element type.

Examples

use wt_indexset::BTreeMap;

let set = BTreeMap::from_iter([(1, "a"), (2, "b"), (3, "c")]);
assert_eq!(set.rank(&1), 0);
assert_eq!(set.rank(&3), 2);
assert_eq!(set.rank(&4), 3);
assert_eq!(set.rank(&100), 3);

Trait Implementations

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

where K: Ord + Clone,

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

Returns a duplicate of the value.

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

Performs copy-assignment from source.

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

where K: Ord + Debug,

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

Formats the value using the given formatter.

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

where K: Ord,

fn default() -> Self

Returns the “default value” for a type.

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

where K: Ord,

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

Converts to this type from the input type.

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

where K: Ord,

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

Creates a value from an iterator.

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

where K: Ord + Hash,

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 BTreeMap<K, V>

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

type Output = V

The returned type after indexing.

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

Performs the indexing (container[index]) operation.

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

where K: Ord,

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

The type of the elements being iterated over.

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

Which kind of iterator are we turning this into?

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

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

where K: Ord,

type Item = (K, V)

The type of the elements being iterated over.

type IntoIter = IntoIterMap<K, V>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

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

where K: Ord + Ord,

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

where K: Ord + PartialEq,

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: PartialOrd> PartialOrd for BTreeMap<K, V>

where K: Ord + PartialOrd,

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

where K: Ord + Eq,

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

where K: Ord,