polars::datatypes

Type Alias PlHashMap

Source
pub type PlHashMap<K, V> = HashMap<K, V, RandomState>;

Aliased Type§

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

Implementations

§

impl<K, V, S> HashMap<K, V, S>

pub const fn with_hasher(hash_builder: S) -> HashMap<K, V, S>

Available on crate feature io_ipc only.

Creates an empty HashMap which will use the given hash builder to hash keys.

The hash map is initially created with a capacity of 0, so it will not allocate until it is first inserted into.

§HashDoS resistance

The hash_builder normally use a fixed key by default and that does not allow the HashMap to be protected against attacks such as HashDoS. Users who require HashDoS resistance should explicitly use std::collections::hash_map::RandomState as the hasher when creating a [HashMap].

The hash_builder passed should implement the BuildHasher trait for the HashMap to be useful, see its documentation for details.

§Examples
use hashbrown::HashMap;
use hashbrown::DefaultHashBuilder;

let s = DefaultHashBuilder::default();
let mut map = HashMap::with_hasher(s);
assert_eq!(map.len(), 0);
assert_eq!(map.capacity(), 0);

map.insert(1, 2);

pub fn with_capacity_and_hasher( capacity: usize, hash_builder: S, ) -> HashMap<K, V, S>

Available on crate feature io_ipc only.

Creates an empty HashMap with the specified capacity, using hash_builder to hash the keys.

The hash map will be able to hold at least capacity elements without reallocating. If capacity is 0, the hash map will not allocate.

§HashDoS resistance

The hash_builder normally use a fixed key by default and that does not allow the HashMap to be protected against attacks such as HashDoS. Users who require HashDoS resistance should explicitly use std::collections::hash_map::RandomState as the hasher when creating a [HashMap].

The hash_builder passed should implement the BuildHasher trait for the HashMap to be useful, see its documentation for details.

§Examples
use hashbrown::HashMap;
use hashbrown::DefaultHashBuilder;

let s = DefaultHashBuilder::default();
let mut map = HashMap::with_capacity_and_hasher(10, s);
assert_eq!(map.len(), 0);
assert!(map.capacity() >= 10);

map.insert(1, 2);
§

impl<K, V, S, A> HashMap<K, V, S, A>
where A: Allocator,

pub fn allocator(&self) -> &A

Available on crate feature io_ipc only.

Returns a reference to the underlying allocator.

pub const fn with_hasher_in(hash_builder: S, alloc: A) -> HashMap<K, V, S, A>

Available on crate feature io_ipc only.

Creates an empty HashMap which will use the given hash builder to hash keys. It will be allocated with the given allocator.

The hash map is initially created with a capacity of 0, so it will not allocate until it is first inserted into.

§HashDoS resistance

The hash_builder normally use a fixed key by default and that does not allow the HashMap to be protected against attacks such as HashDoS. Users who require HashDoS resistance should explicitly use std::collections::hash_map::RandomState as the hasher when creating a [HashMap].

§Examples
use hashbrown::HashMap;
use hashbrown::DefaultHashBuilder;

let s = DefaultHashBuilder::default();
let mut map = HashMap::with_hasher(s);
map.insert(1, 2);

pub fn with_capacity_and_hasher_in( capacity: usize, hash_builder: S, alloc: A, ) -> HashMap<K, V, S, A>

Available on crate feature io_ipc only.

Creates an empty HashMap with the specified capacity, using hash_builder to hash the keys. It will be allocated with the given allocator.

The hash map will be able to hold at least capacity elements without reallocating. If capacity is 0, the hash map will not allocate.

§HashDoS resistance

The hash_builder normally use a fixed key by default and that does not allow the HashMap to be protected against attacks such as HashDoS. Users who require HashDoS resistance should explicitly use std::collections::hash_map::RandomState as the hasher when creating a [HashMap].

§Examples
use hashbrown::HashMap;
use hashbrown::DefaultHashBuilder;

let s = DefaultHashBuilder::default();
let mut map = HashMap::with_capacity_and_hasher(10, s);
map.insert(1, 2);

pub fn hasher(&self) -> &S

Available on crate feature io_ipc only.

Returns a reference to the map’s BuildHasher.

§Examples
use hashbrown::HashMap;
use hashbrown::DefaultHashBuilder;

let hasher = DefaultHashBuilder::default();
let map: HashMap<i32, i32> = HashMap::with_hasher(hasher);
let hasher: &DefaultHashBuilder = map.hasher();

pub fn capacity(&self) -> usize

Available on crate feature io_ipc only.

Returns the number of elements the map can hold without reallocating.

This number is a lower bound; the HashMap<K, V> might be able to hold more, but is guaranteed to be able to hold at least this many.

§Examples
use hashbrown::HashMap;
let map: HashMap<i32, i32> = HashMap::with_capacity(100);
assert_eq!(map.len(), 0);
assert!(map.capacity() >= 100);

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

Available on crate feature io_ipc only.

An iterator visiting all keys in arbitrary order. The iterator element type is &'a K.

§Examples
use hashbrown::HashMap;

let mut map = HashMap::new();
map.insert("a", 1);
map.insert("b", 2);
map.insert("c", 3);
assert_eq!(map.len(), 3);
let mut vec: Vec<&str> = Vec::new();

for key in map.keys() {
    println!("{}", key);
    vec.push(*key);
}

// The `Keys` iterator produces keys in arbitrary order, so the
// keys must be sorted to test them against a sorted array.
vec.sort_unstable();
assert_eq!(vec, ["a", "b", "c"]);

assert_eq!(map.len(), 3);

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

Available on crate feature io_ipc only.

An iterator visiting all values in arbitrary order. The iterator element type is &'a V.

§Examples
use hashbrown::HashMap;

let mut map = HashMap::new();
map.insert("a", 1);
map.insert("b", 2);
map.insert("c", 3);
assert_eq!(map.len(), 3);
let mut vec: Vec<i32> = Vec::new();

for val in map.values() {
    println!("{}", val);
    vec.push(*val);
}

// The `Values` iterator produces values in arbitrary order, so the
// values must be sorted to test them against a sorted array.
vec.sort_unstable();
assert_eq!(vec, [1, 2, 3]);

assert_eq!(map.len(), 3);

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

Available on crate feature io_ipc only.

An iterator visiting all values mutably in arbitrary order. The iterator element type is &'a mut V.

§Examples
use hashbrown::HashMap;

let mut map = HashMap::new();

map.insert("a", 1);
map.insert("b", 2);
map.insert("c", 3);

for val in map.values_mut() {
    *val = *val + 10;
}

assert_eq!(map.len(), 3);
let mut vec: Vec<i32> = Vec::new();

for val in map.values() {
    println!("{}", val);
    vec.push(*val);
}

// The `Values` iterator produces values in arbitrary order, so the
// values must be sorted to test them against a sorted array.
vec.sort_unstable();
assert_eq!(vec, [11, 12, 13]);

assert_eq!(map.len(), 3);

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

Available on crate feature io_ipc only.

An iterator visiting all key-value pairs in arbitrary order. The iterator element type is (&'a K, &'a V).

§Examples
use hashbrown::HashMap;

let mut map = HashMap::new();
map.insert("a", 1);
map.insert("b", 2);
map.insert("c", 3);
assert_eq!(map.len(), 3);
let mut vec: Vec<(&str, i32)> = Vec::new();

for (key, val) in map.iter() {
    println!("key: {} val: {}", key, val);
    vec.push((*key, *val));
}

// The `Iter` iterator produces items in arbitrary order, so the
// items must be sorted to test them against a sorted array.
vec.sort_unstable();
assert_eq!(vec, [("a", 1), ("b", 2), ("c", 3)]);

assert_eq!(map.len(), 3);

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

Available on crate feature io_ipc only.

An iterator visiting all key-value pairs in arbitrary order, with mutable references to the values. The iterator element type is (&'a K, &'a mut V).

§Examples
use hashbrown::HashMap;

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

// Update all values
for (_, val) in map.iter_mut() {
    *val *= 2;
}

assert_eq!(map.len(), 3);
let mut vec: Vec<(&str, i32)> = Vec::new();

for (key, val) in &map {
    println!("key: {} val: {}", key, val);
    vec.push((*key, *val));
}

// The `Iter` iterator produces items in arbitrary order, so the
// items must be sorted to test them against a sorted array.
vec.sort_unstable();
assert_eq!(vec, [("a", 2), ("b", 4), ("c", 6)]);

assert_eq!(map.len(), 3);

pub fn len(&self) -> usize

Available on crate feature io_ipc only.

Returns the number of elements in the map.

§Examples
use hashbrown::HashMap;

let mut a = HashMap::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 io_ipc only.

Returns true if the map contains no elements.

§Examples
use hashbrown::HashMap;

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

pub fn drain(&mut self) -> Drain<'_, K, V, A>

Available on crate feature io_ipc only.

Clears the map, returning all key-value pairs as an iterator. Keeps the allocated memory for reuse.

If the returned iterator is dropped before being fully consumed, it drops the remaining key-value pairs. The returned iterator keeps a mutable borrow on the vector to optimize its implementation.

§Examples
use hashbrown::HashMap;

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

for (k, v) in a.drain().take(1) {
    assert!(k == 1 || k == 2);
    assert!(v == "a" || v == "b");
}

// As we can see, the map is empty and contains no element.
assert!(a.is_empty() && a.len() == 0);
// But map capacity is equal to old one.
assert_eq!(a.capacity(), capacity_before_drain);

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

{   // Iterator is dropped without being consumed.
    let d = a.drain();
}

// But the map is empty even if we do not use Drain iterator.
assert!(a.is_empty());

pub fn retain<F>(&mut self, f: F)
where F: FnMut(&K, &mut V) -> bool,

Available on crate feature io_ipc only.

Retains only the elements specified by the predicate. Keeps the allocated memory for reuse.

In other words, remove all pairs (k, v) such that f(&k, &mut v) returns false. The elements are visited in unsorted (and unspecified) order.

§Examples
use hashbrown::HashMap;

let mut map: HashMap<i32, i32> = (0..8).map(|x|(x, x*10)).collect();
assert_eq!(map.len(), 8);

map.retain(|&k, _| k % 2 == 0);

// We can see, that the number of elements inside map is changed.
assert_eq!(map.len(), 4);

let mut vec: Vec<(i32, i32)> = map.iter().map(|(&k, &v)| (k, v)).collect();
vec.sort_unstable();
assert_eq!(vec, [(0, 0), (2, 20), (4, 40), (6, 60)]);

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

Available on crate feature io_ipc only.

Drains elements which are true under the given predicate, and returns an iterator over the removed items.

In other words, move all pairs (k, v) such that f(&k, &mut v) returns true out into another iterator.

Note that extract_if lets you mutate every value in the filter 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.

Keeps the allocated memory for reuse.

§Examples
use hashbrown::HashMap;

let mut map: HashMap<i32, i32> = (0..8).map(|x| (x, x)).collect();

let drained: HashMap<i32, i32> = map.extract_if(|k, _v| k % 2 == 0).collect();

let mut evens = drained.keys().cloned().collect::<Vec<_>>();
let mut odds = map.keys().cloned().collect::<Vec<_>>();
evens.sort();
odds.sort();

assert_eq!(evens, vec![0, 2, 4, 6]);
assert_eq!(odds, vec![1, 3, 5, 7]);

let mut map: HashMap<i32, i32> = (0..8).map(|x| (x, x)).collect();

{   // Iterator is dropped without being consumed.
    let d = map.extract_if(|k, _v| k % 2 != 0);
}

// ExtractIf was not exhausted, therefore no elements were drained.
assert_eq!(map.len(), 8);

pub fn clear(&mut self)

Available on crate feature io_ipc only.

Clears the map, removing all key-value pairs. Keeps the allocated memory for reuse.

§Examples
use hashbrown::HashMap;

let mut a = HashMap::new();
a.insert(1, "a");
let capacity_before_clear = a.capacity();

a.clear();

// Map is empty.
assert!(a.is_empty());
// But map capacity is equal to old one.
assert_eq!(a.capacity(), capacity_before_clear);

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

Available on crate feature io_ipc only.

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

§Examples
use hashbrown::HashMap;

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

let mut vec: Vec<&str> = map.into_keys().collect();

// The `IntoKeys` iterator produces keys in arbitrary order, so the
// keys must be sorted to test them against a sorted array.
vec.sort_unstable();
assert_eq!(vec, ["a", "b", "c"]);

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

Available on crate feature io_ipc only.

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

§Examples
use hashbrown::HashMap;

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

let mut vec: Vec<i32> = map.into_values().collect();

// The `IntoValues` iterator produces values in arbitrary order, so
// the values must be sorted to test them against a sorted array.
vec.sort_unstable();
assert_eq!(vec, [1, 2, 3]);
§

impl<K, V, S, A> HashMap<K, V, S, A>
where A: Allocator,

pub fn raw_entry_mut(&mut self) -> RawEntryBuilderMut<'_, K, V, S, A>

Available on crate feature io_ipc only.

Creates a raw entry builder for the HashMap.

Raw entries provide the lowest level of control for searching and manipulating a map. They must be manually initialized with a hash and then manually searched. After this, insertions into a vacant entry still require an owned key to be provided.

Raw entries are useful for such exotic situations as:

  • Hash memoization
  • Deferring the creation of an owned key until it is known to be required
  • Using a search key that doesn’t work with the Borrow trait
  • Using custom comparison logic without newtype wrappers

Because raw entries provide much more low-level control, it’s much easier to put the HashMap into an inconsistent state which, while memory-safe, will cause the map to produce seemingly random results. Higher-level and more foolproof APIs like entry should be preferred when possible.

In particular, the hash used to initialized the raw entry must still be consistent with the hash of the key that is ultimately stored in the entry. This is because implementations of HashMap may need to recompute hashes when resizing, at which point only the keys are available.

Raw entries give mutable access to the keys. This must not be used to modify how the key would compare or hash, as the map will not re-evaluate where the key should go, meaning the keys may become “lost” if their location does not reflect their state. For instance, if you change a key so that the map now contains keys which compare equal, search may start acting erratically, with two keys randomly masking each other. Implementations are free to assume this doesn’t happen (within the limits of memory-safety).

§Examples
use core::hash::{BuildHasher, Hash};
use hashbrown::hash_map::{HashMap, RawEntryMut};

let mut map = HashMap::new();
map.extend([("a", 100), ("b", 200), ("c", 300)]);

fn compute_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 {
    use core::hash::Hasher;
    let mut state = hash_builder.build_hasher();
    key.hash(&mut state);
    state.finish()
}

// Existing key (insert and update)
match map.raw_entry_mut().from_key(&"a") {
    RawEntryMut::Vacant(_) => unreachable!(),
    RawEntryMut::Occupied(mut view) => {
        assert_eq!(view.get(), &100);
        let v = view.get_mut();
        let new_v = (*v) * 10;
        *v = new_v;
        assert_eq!(view.insert(1111), 1000);
    }
}

assert_eq!(map[&"a"], 1111);
assert_eq!(map.len(), 3);

// Existing key (take)
let hash = compute_hash(map.hasher(), &"c");
match map.raw_entry_mut().from_key_hashed_nocheck(hash, &"c") {
    RawEntryMut::Vacant(_) => unreachable!(),
    RawEntryMut::Occupied(view) => {
        assert_eq!(view.remove_entry(), ("c", 300));
    }
}
assert_eq!(map.raw_entry().from_key(&"c"), None);
assert_eq!(map.len(), 2);

// Nonexistent key (insert and update)
let key = "d";
let hash = compute_hash(map.hasher(), &key);
match map.raw_entry_mut().from_hash(hash, |q| *q == key) {
    RawEntryMut::Occupied(_) => unreachable!(),
    RawEntryMut::Vacant(view) => {
        let (k, value) = view.insert("d", 4000);
        assert_eq!((*k, *value), ("d", 4000));
        *value = 40000;
    }
}
assert_eq!(map[&"d"], 40000);
assert_eq!(map.len(), 3);

match map.raw_entry_mut().from_hash(hash, |q| *q == key) {
    RawEntryMut::Vacant(_) => unreachable!(),
    RawEntryMut::Occupied(view) => {
        assert_eq!(view.remove_entry(), ("d", 40000));
    }
}
assert_eq!(map.get(&"d"), None);
assert_eq!(map.len(), 2);

pub fn raw_entry(&self) -> RawEntryBuilder<'_, K, V, S, A>

Available on crate feature io_ipc only.

Creates a raw immutable entry builder for the HashMap.

Raw entries provide the lowest level of control for searching and manipulating a map. They must be manually initialized with a hash and then manually searched.

This is useful for

  • Hash memoization
  • Using a search key that doesn’t work with the Borrow trait
  • Using custom comparison logic without newtype wrappers

Unless you are in such a situation, higher-level and more foolproof APIs like get should be preferred.

Immutable raw entries have very limited use; you might instead want raw_entry_mut.

§Examples
use core::hash::{BuildHasher, Hash};
use hashbrown::HashMap;

let mut map = HashMap::new();
map.extend([("a", 100), ("b", 200), ("c", 300)]);

fn compute_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 {
    use core::hash::Hasher;
    let mut state = hash_builder.build_hasher();
    key.hash(&mut state);
    state.finish()
}

for k in ["a", "b", "c", "d", "e", "f"] {
    let hash = compute_hash(map.hasher(), k);
    let v = map.get(&k).cloned();
    let kv = v.as_ref().map(|v| (&k, v));

    println!("Key: {} and value: {:?}", k, v);

    assert_eq!(map.raw_entry().from_key(&k), kv);
    assert_eq!(map.raw_entry().from_hash(hash, |q| *q == k), kv);
    assert_eq!(map.raw_entry().from_key_hashed_nocheck(hash, &k), kv);
}
§

impl<K, V, S, A> HashMap<K, V, S, A>
where K: Eq + Hash + Sync, V: PartialEq + Sync, S: BuildHasher + Sync, A: Allocator + Sync,

pub fn par_eq(&self, other: &HashMap<K, V, S, A>) -> bool

Available on crate feature io_ipc only.

Returns true if the map is equal to another, i.e. both maps contain the same keys mapped to the same values.

This method runs in a potentially parallel fashion.

§

impl<K, V, S, A> HashMap<K, V, S, A>
where K: Eq + Hash, S: BuildHasher, A: Allocator,

pub fn reserve(&mut self, additional: usize)

Available on crate feature io_ipc only.

Reserves capacity for at least additional more elements to be inserted in the HashMap. The collection may reserve more space to avoid frequent reallocations.

§Panics

Panics if the new capacity exceeds isize::MAX bytes and abort the program in case of allocation error. Use try_reserve instead if you want to handle memory allocation failure.

§Examples
use hashbrown::HashMap;
let mut map: HashMap<&str, i32> = HashMap::new();
// Map is empty and doesn't allocate memory
assert_eq!(map.capacity(), 0);

map.reserve(10);

// And now map can hold at least 10 elements
assert!(map.capacity() >= 10);

pub fn try_reserve(&mut self, additional: usize) -> Result<(), TryReserveError>

Available on crate feature io_ipc only.

Tries to reserve capacity for at least additional more elements to be inserted in the given HashMap<K,V>. The collection may reserve more space to avoid frequent reallocations.

§Errors

If the capacity overflows, or the allocator reports a failure, then an error is returned.

§Examples
use hashbrown::HashMap;

let mut map: HashMap<&str, isize> = HashMap::new();
// Map is empty and doesn't allocate memory
assert_eq!(map.capacity(), 0);

map.try_reserve(10).expect("why is the test harness OOMing on 10 bytes?");

// And now map can hold at least 10 elements
assert!(map.capacity() >= 10);

If the capacity overflows, or the allocator reports a failure, then an error is returned:

use hashbrown::HashMap;
use hashbrown::TryReserveError;
let mut map: HashMap<i32, i32> = HashMap::new();

match map.try_reserve(usize::MAX) {
    Err(error) => match error {
        TryReserveError::CapacityOverflow => {}
        _ => panic!("TryReserveError::AllocError ?"),
    },
    _ => panic!(),
}

pub fn shrink_to_fit(&mut self)

Available on crate feature io_ipc only.

Shrinks the capacity of the map as much as possible. It will drop down as much as possible while maintaining the internal rules and possibly leaving some space in accordance with the resize policy.

§Examples
use hashbrown::HashMap;

let mut map: HashMap<i32, i32> = HashMap::with_capacity(100);
map.insert(1, 2);
map.insert(3, 4);
assert!(map.capacity() >= 100);
map.shrink_to_fit();
assert!(map.capacity() >= 2);

pub fn shrink_to(&mut self, min_capacity: usize)

Available on crate feature io_ipc only.

Shrinks the capacity of the map with a lower limit. It will drop down no lower than the supplied limit while maintaining the internal rules and possibly leaving some space in accordance with the resize policy.

This function does nothing if the current capacity is smaller than the supplied minimum capacity.

§Examples
use hashbrown::HashMap;

let mut map: HashMap<i32, i32> = HashMap::with_capacity(100);
map.insert(1, 2);
map.insert(3, 4);
assert!(map.capacity() >= 100);
map.shrink_to(10);
assert!(map.capacity() >= 10);
map.shrink_to(0);
assert!(map.capacity() >= 2);
map.shrink_to(10);
assert!(map.capacity() >= 2);

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

Available on crate feature io_ipc only.

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

§Examples
use hashbrown::HashMap;

let mut letters = HashMap::new();

for ch in "a short treatise on fungi".chars() {
    let counter = letters.entry(ch).or_insert(0);
    *counter += 1;
}

assert_eq!(letters[&'s'], 2);
assert_eq!(letters[&'t'], 3);
assert_eq!(letters[&'u'], 1);
assert_eq!(letters.get(&'y'), None);

pub fn entry_ref<'a, 'b, Q>( &'a mut self, key: &'b Q, ) -> EntryRef<'a, 'b, K, Q, V, S, A>
where Q: Hash + Equivalent<K> + ?Sized,

Available on crate feature io_ipc only.

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

§Examples
use hashbrown::HashMap;

let mut words: HashMap<String, usize> = HashMap::new();
let source = ["poneyland", "horseyland", "poneyland", "poneyland"];
for (i, &s) in source.iter().enumerate() {
    let counter = words.entry_ref(s).or_insert(0);
    *counter += 1;
}

assert_eq!(words["poneyland"], 3);
assert_eq!(words["horseyland"], 1);

pub fn get<Q>(&self, k: &Q) -> Option<&V>
where Q: Hash + Equivalent<K> + ?Sized,

Available on crate feature io_ipc 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 Hash and Eq on the borrowed form must match those for the key type.

§Examples
use hashbrown::HashMap;

let mut map = HashMap::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 Q: Hash + Equivalent<K> + ?Sized,

Available on crate feature io_ipc only.

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 Hash and Eq on the borrowed form must match those for the key type.

§Examples
use hashbrown::HashMap;

let mut map = HashMap::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_key_value_mut<Q>(&mut self, k: &Q) -> Option<(&K, &mut V)>
where Q: Hash + Equivalent<K> + ?Sized,

Available on crate feature io_ipc only.

Returns the key-value pair corresponding to the supplied key, with a mutable reference to value.

The supplied key may be any borrowed form of the map’s key type, but Hash and Eq on the borrowed form must match those for the key type.

§Examples
use hashbrown::HashMap;

let mut map = HashMap::new();
map.insert(1, "a");
let (k, v) = map.get_key_value_mut(&1).unwrap();
assert_eq!(k, &1);
assert_eq!(v, &mut "a");
*v = "b";
assert_eq!(map.get_key_value_mut(&1), Some((&1, &mut "b")));
assert_eq!(map.get_key_value_mut(&2), None);

pub fn contains_key<Q>(&self, k: &Q) -> bool
where Q: Hash + Equivalent<K> + ?Sized,

Available on crate feature io_ipc 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 Hash and Eq on the borrowed form must match those for the key type.

§Examples
use hashbrown::HashMap;

let mut map = HashMap::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, k: &Q) -> Option<&mut V>
where Q: Hash + Equivalent<K> + ?Sized,

Available on crate feature io_ipc 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 Hash and Eq on the borrowed form must match those for the key type.

§Examples
use hashbrown::HashMap;

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

assert_eq!(map.get_mut(&2), None);

pub fn get_many_mut<Q, const N: usize>( &mut self, ks: [&Q; N], ) -> [Option<&mut V>; N]
where Q: Hash + Equivalent<K> + ?Sized,

Available on crate feature io_ipc only.

Attempts to get mutable references to N values in the map at once.

Returns an array of length N with the results of each query. For soundness, at most one mutable reference will be returned to any value. None will be used if the key is missing.

§Panics

Panics if any keys are overlapping.

§Examples
use hashbrown::HashMap;

let mut libraries = HashMap::new();
libraries.insert("Bodleian Library".to_string(), 1602);
libraries.insert("Athenæum".to_string(), 1807);
libraries.insert("Herzogin-Anna-Amalia-Bibliothek".to_string(), 1691);
libraries.insert("Library of Congress".to_string(), 1800);

// Get Athenæum and Bodleian Library
let [Some(a), Some(b)] = libraries.get_many_mut([
    "Athenæum",
    "Bodleian Library",
]) else { panic!() };

// Assert values of Athenæum and Library of Congress
let got = libraries.get_many_mut([
    "Athenæum",
    "Library of Congress",
]);
assert_eq!(
    got,
    [
        Some(&mut 1807),
        Some(&mut 1800),
    ],
);

// Missing keys result in None
let got = libraries.get_many_mut([
    "Athenæum",
    "New York Public Library",
]);
assert_eq!(
    got,
    [
        Some(&mut 1807),
        None
    ]
);
use hashbrown::HashMap;

let mut libraries = HashMap::new();
libraries.insert("Athenæum".to_string(), 1807);

// Duplicate keys panic!
let got = libraries.get_many_mut([
    "Athenæum",
    "Athenæum",
]);

pub unsafe fn get_many_unchecked_mut<Q, const N: usize>( &mut self, ks: [&Q; N], ) -> [Option<&mut V>; N]
where Q: Hash + Equivalent<K> + ?Sized,

Available on crate feature io_ipc only.

Attempts to get mutable references to N values in the map at once, without validating that the values are unique.

Returns an array of length N with the results of each query. None will be used if the key is missing.

For a safe alternative see get_many_mut.

§Safety

Calling this method with overlapping keys is undefined behavior even if the resulting references are not used.

§Examples
use hashbrown::HashMap;

let mut libraries = HashMap::new();
libraries.insert("Bodleian Library".to_string(), 1602);
libraries.insert("Athenæum".to_string(), 1807);
libraries.insert("Herzogin-Anna-Amalia-Bibliothek".to_string(), 1691);
libraries.insert("Library of Congress".to_string(), 1800);

// SAFETY: The keys do not overlap.
let [Some(a), Some(b)] = (unsafe { libraries.get_many_unchecked_mut([
    "Athenæum",
    "Bodleian Library",
]) }) else { panic!() };

// SAFETY: The keys do not overlap.
let got = unsafe { libraries.get_many_unchecked_mut([
    "Athenæum",
    "Library of Congress",
]) };
assert_eq!(
    got,
    [
        Some(&mut 1807),
        Some(&mut 1800),
    ],
);

// SAFETY: The keys do not overlap.
let got = unsafe { libraries.get_many_unchecked_mut([
    "Athenæum",
    "New York Public Library",
]) };
// Missing keys result in None
assert_eq!(got, [Some(&mut 1807), None]);

pub fn get_many_key_value_mut<Q, const N: usize>( &mut self, ks: [&Q; N], ) -> [Option<(&K, &mut V)>; N]
where Q: Hash + Equivalent<K> + ?Sized,

Available on crate feature io_ipc only.

Attempts to get mutable references to N values in the map at once, with immutable references to the corresponding keys.

Returns an array of length N with the results of each query. For soundness, at most one mutable reference will be returned to any value. None will be used if the key is missing.

§Panics

Panics if any keys are overlapping.

§Examples
use hashbrown::HashMap;

let mut libraries = HashMap::new();
libraries.insert("Bodleian Library".to_string(), 1602);
libraries.insert("Athenæum".to_string(), 1807);
libraries.insert("Herzogin-Anna-Amalia-Bibliothek".to_string(), 1691);
libraries.insert("Library of Congress".to_string(), 1800);

let got = libraries.get_many_key_value_mut([
    "Bodleian Library",
    "Herzogin-Anna-Amalia-Bibliothek",
]);
assert_eq!(
    got,
    [
        Some((&"Bodleian Library".to_string(), &mut 1602)),
        Some((&"Herzogin-Anna-Amalia-Bibliothek".to_string(), &mut 1691)),
    ],
);
// Missing keys result in None
let got = libraries.get_many_key_value_mut([
    "Bodleian Library",
    "Gewandhaus",
]);
assert_eq!(got, [Some((&"Bodleian Library".to_string(), &mut 1602)), None]);
use hashbrown::HashMap;

let mut libraries = HashMap::new();
libraries.insert("Bodleian Library".to_string(), 1602);
libraries.insert("Herzogin-Anna-Amalia-Bibliothek".to_string(), 1691);

// Duplicate keys result in panic!
let got = libraries.get_many_key_value_mut([
    "Bodleian Library",
    "Herzogin-Anna-Amalia-Bibliothek",
    "Herzogin-Anna-Amalia-Bibliothek",
]);

pub unsafe fn get_many_key_value_unchecked_mut<Q, const N: usize>( &mut self, ks: [&Q; N], ) -> [Option<(&K, &mut V)>; N]
where Q: Hash + Equivalent<K> + ?Sized,

Available on crate feature io_ipc only.

Attempts to get mutable references to N values in the map at once, with immutable references to the corresponding keys, without validating that the values are unique.

Returns an array of length N with the results of each query. None will be returned if any of the keys are missing.

For a safe alternative see get_many_key_value_mut.

§Safety

Calling this method with overlapping keys is undefined behavior even if the resulting references are not used.

§Examples
use hashbrown::HashMap;

let mut libraries = HashMap::new();
libraries.insert("Bodleian Library".to_string(), 1602);
libraries.insert("Athenæum".to_string(), 1807);
libraries.insert("Herzogin-Anna-Amalia-Bibliothek".to_string(), 1691);
libraries.insert("Library of Congress".to_string(), 1800);

let got = libraries.get_many_key_value_mut([
    "Bodleian Library",
    "Herzogin-Anna-Amalia-Bibliothek",
]);
assert_eq!(
    got,
    [
        Some((&"Bodleian Library".to_string(), &mut 1602)),
        Some((&"Herzogin-Anna-Amalia-Bibliothek".to_string(), &mut 1691)),
    ],
);
// Missing keys result in None
let got = libraries.get_many_key_value_mut([
    "Bodleian Library",
    "Gewandhaus",
]);
assert_eq!(
    got,
    [
        Some((&"Bodleian Library".to_string(), &mut 1602)),
        None,
    ],
);

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

Available on crate feature io_ipc 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 std::collections module-level documentation for more.

§Examples
use hashbrown::HashMap;

let mut map = HashMap::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 unsafe fn insert_unique_unchecked(&mut self, k: K, v: V) -> (&K, &mut V)

Available on crate feature io_ipc only.

Insert a key-value pair into the map without checking if the key already exists in the map.

This operation is faster than regular insert, because it does not perform lookup before insertion.

This operation is useful during initial population of the map. For example, when constructing a map from another map, we know that keys are unique.

Returns a reference to the key and value just inserted.

§Safety

This operation is safe if a key does not exist in the map.

However, if a key exists in the map already, the behavior is unspecified: this operation may panic, loop forever, or any following operation with the map may panic, loop forever or return arbitrary result.

That said, this operation (and following operations) are guaranteed to not violate memory safety.

However this operation is still unsafe because the resulting HashMap may be passed to unsafe code which does expect the map to behave correctly, and would cause unsoundness as a result.

§Examples
use hashbrown::HashMap;

let mut map1 = HashMap::new();
assert_eq!(map1.insert(1, "a"), None);
assert_eq!(map1.insert(2, "b"), None);
assert_eq!(map1.insert(3, "c"), None);
assert_eq!(map1.len(), 3);

let mut map2 = HashMap::new();

for (key, value) in map1.into_iter() {
    unsafe {
        map2.insert_unique_unchecked(key, value);
    }
}

let (key, value) = unsafe { map2.insert_unique_unchecked(4, "d") };
assert_eq!(key, &4);
assert_eq!(value, &mut "d");
*value = "e";

assert_eq!(map2[&1], "a");
assert_eq!(map2[&2], "b");
assert_eq!(map2[&3], "c");
assert_eq!(map2[&4], "e");
assert_eq!(map2.len(), 4);

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

Available on crate feature io_ipc only.

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

§Errors

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

§Examples

Basic usage:

use hashbrown::HashMap;
use hashbrown::hash_map::OccupiedError;

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

match map.try_insert(37, "b") {
    Err(OccupiedError { entry, value }) => {
        assert_eq!(entry.key(), &37);
        assert_eq!(entry.get(), &"a");
        assert_eq!(value, "b");
    }
    _ => panic!()
}

pub fn remove<Q>(&mut self, k: &Q) -> Option<V>
where Q: Hash + Equivalent<K> + ?Sized,

Available on crate feature io_ipc only.

Removes a key from the map, returning the value at the key if the key was previously in the map. Keeps the allocated memory for reuse.

The key may be any borrowed form of the map’s key type, but Hash and Eq on the borrowed form must match those for the key type.

§Examples
use hashbrown::HashMap;

let mut map = HashMap::new();
// The map is empty
assert!(map.is_empty() && map.capacity() == 0);

map.insert(1, "a");

assert_eq!(map.remove(&1), Some("a"));
assert_eq!(map.remove(&1), None);

// Now map holds none elements
assert!(map.is_empty());

pub fn remove_entry<Q>(&mut self, k: &Q) -> Option<(K, V)>
where Q: Hash + Equivalent<K> + ?Sized,

Available on crate feature io_ipc only.

Removes a key from the map, returning the stored key and value if the key was previously in the map. Keeps the allocated memory for reuse.

The key may be any borrowed form of the map’s key type, but Hash and Eq on the borrowed form must match those for the key type.

§Examples
use hashbrown::HashMap;

let mut map = HashMap::new();
// The map is empty
assert!(map.is_empty() && map.capacity() == 0);

map.insert(1, "a");

assert_eq!(map.remove_entry(&1), Some((1, "a")));
assert_eq!(map.remove(&1), None);

// Now map hold none elements
assert!(map.is_empty());

pub fn allocation_size(&self) -> usize

Available on crate feature io_ipc only.

Returns the total amount of memory allocated internally by the hash set, in bytes.

The returned number is informational only. It is intended to be primarily used for memory profiling.

§

impl<K, V, S, A> HashMap<K, V, S, A>
where K: Send, V: Send, A: Allocator,

pub fn par_values_mut(&mut self) -> ParValuesMut<'_, K, V>

Available on crate feature io_ipc only.

Visits (potentially in parallel) mutably borrowed values in an arbitrary order.

pub fn par_drain(&mut self) -> ParDrain<'_, K, V, A>

Available on crate feature io_ipc only.

Consumes (potentially in parallel) all values in an arbitrary order, while preserving the map’s allocated memory for reuse.

§

impl<K, V, S, A> HashMap<K, V, S, A>
where K: Sync, V: Sync, A: Allocator,

pub fn par_keys(&self) -> ParKeys<'_, K, V>

Available on crate feature io_ipc only.

Visits (potentially in parallel) immutably borrowed keys in an arbitrary order.

pub fn par_values(&self) -> ParValues<'_, K, V>

Available on crate feature io_ipc only.

Visits (potentially in parallel) immutably borrowed values in an arbitrary order.

Trait Implementations

§

impl<K, V, S, A> Clone for HashMap<K, V, S, A>
where K: Clone, V: Clone, S: Clone, A: Allocator + Clone,

§

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

Returns a copy of the value. Read more
§

fn clone_from(&mut self, source: &HashMap<K, V, S, A>)

Performs copy-assignment from source. Read more
§

impl<K, V, S, A> Debug for HashMap<K, V, S, A>
where K: Debug, V: Debug, A: Allocator,

§

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

Formats the value using the given formatter. Read more
§

impl<K, V, S, A> Default for HashMap<K, V, S, A>
where S: Default, A: Default + Allocator,

§

fn default() -> HashMap<K, V, S, A>

Creates an empty HashMap<K, V, S, A>, with the Default value for the hasher and allocator.

§Examples
use hashbrown::HashMap;
use std::collections::hash_map::RandomState;

// You can specify all types of HashMap, including hasher and allocator.
// Created map is empty and don't allocate memory
let map: HashMap<u32, String> = Default::default();
assert_eq!(map.capacity(), 0);
let map: HashMap<u32, String, RandomState> = HashMap::default();
assert_eq!(map.capacity(), 0);
§

impl<'de, K, V, S, A> Deserialize<'de> for HashMap<K, V, S, A>
where K: Deserialize<'de> + Eq + Hash, V: Deserialize<'de>, S: BuildHasher + Default, A: Allocator + Default,

§

fn deserialize<D>( deserializer: D, ) -> Result<HashMap<K, V, S, A>, <D as Deserializer<'de>>::Error>
where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer. Read more
§

impl<'a, K, V, S, A> Extend<&'a (K, V)> for HashMap<K, V, S, A>
where K: Eq + Hash + Copy, V: Copy, S: BuildHasher, A: Allocator,

Inserts all new key-values from the iterator and replaces values with existing keys with new values returned from the iterator.

§

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

Inserts all new key-values from the iterator to existing HashMap<K, V, S, A>. Replace values with existing keys with new values returned from the iterator. The keys and values must implement Copy trait.

§Examples
use hashbrown::hash_map::HashMap;

let mut map = HashMap::new();
map.insert(1, 100);

let arr = [(1, 1), (2, 2)];
let some_iter = arr.iter();
map.extend(some_iter);
// Replace values with existing keys with new values returned from the iterator.
// So that the map.get(&1) doesn't return Some(&100).
assert_eq!(map.get(&1), Some(&1));

let some_vec: Vec<_> = vec![(3, 3), (4, 4)];
map.extend(&some_vec);

let some_arr = [(5, 5), (6, 6)];
map.extend(&some_arr);

let mut vec: Vec<_> = map.into_iter().collect();
// The `IntoIter` iterator produces items in arbitrary order, so the
// items must be sorted to test them against a sorted array.
vec.sort_unstable();
assert_eq!(vec, [(1, 1), (2, 2), (3, 3), (4, 4), (5, 5), (6, 6)]);
Source§

fn extend_one(&mut self, item: A)

🔬This is a nightly-only experimental API. (extend_one)
Extends a collection with exactly one element.
Source§

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. Read more
§

impl<'a, K, V, S, A> Extend<(&'a K, &'a V)> for HashMap<K, V, S, A>
where K: Eq + Hash + Copy, V: Copy, S: BuildHasher, A: Allocator,

Inserts all new key-values from the iterator and replaces values with existing keys with new values returned from the iterator.

§

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

Inserts all new key-values from the iterator to existing HashMap<K, V, S, A>. Replace values with existing keys with new values returned from the iterator. The keys and values must implement Copy trait.

§Examples
use hashbrown::hash_map::HashMap;

let mut map = HashMap::new();
map.insert(1, 100);

let arr = [(1, 1), (2, 2)];
let some_iter = arr.iter().map(|(k, v)| (k, v));
map.extend(some_iter);
// Replace values with existing keys with new values returned from the iterator.
// So that the map.get(&1) doesn't return Some(&100).
assert_eq!(map.get(&1), Some(&1));

let some_vec: Vec<_> = vec![(3, 3), (4, 4)];
map.extend(some_vec.iter().map(|(k, v)| (k, v)));

let some_arr = [(5, 5), (6, 6)];
map.extend(some_arr.iter().map(|(k, v)| (k, v)));

// You can also extend from another HashMap
let mut new_map = HashMap::new();
new_map.extend(&map);
assert_eq!(new_map, map);

let mut vec: Vec<_> = new_map.into_iter().collect();
// The `IntoIter` iterator produces items in arbitrary order, so the
// items must be sorted to test them against a sorted array.
vec.sort_unstable();
assert_eq!(vec, [(1, 1), (2, 2), (3, 3), (4, 4), (5, 5), (6, 6)]);
Source§

fn extend_one(&mut self, item: A)

🔬This is a nightly-only experimental API. (extend_one)
Extends a collection with exactly one element.
Source§

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. Read more
§

impl<K, V, S, A> Extend<(K, V)> for HashMap<K, V, S, A>
where K: Eq + Hash, S: BuildHasher, A: Allocator,

Inserts all new key-values from the iterator and replaces values with existing keys with new values returned from the iterator.

§

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

Inserts all new key-values from the iterator to existing HashMap<K, V, S, A>. Replace values with existing keys with new values returned from the iterator.

§Examples
use hashbrown::hash_map::HashMap;

let mut map = HashMap::new();
map.insert(1, 100);

let some_iter = [(1, 1), (2, 2)].into_iter();
map.extend(some_iter);
// Replace values with existing keys with new values returned from the iterator.
// So that the map.get(&1) doesn't return Some(&100).
assert_eq!(map.get(&1), Some(&1));

let some_vec: Vec<_> = vec![(3, 3), (4, 4)];
map.extend(some_vec);

let some_arr = [(5, 5), (6, 6)];
map.extend(some_arr);
let old_map_len = map.len();

// You can also extend from another HashMap
let mut new_map = HashMap::new();
new_map.extend(map);
assert_eq!(new_map.len(), old_map_len);

let mut vec: Vec<_> = new_map.into_iter().collect();
// The `IntoIter` iterator produces items in arbitrary order, so the
// items must be sorted to test them against a sorted array.
vec.sort_unstable();
assert_eq!(vec, [(1, 1), (2, 2), (3, 3), (4, 4), (5, 5), (6, 6)]);
Source§

fn extend_one(&mut self, item: A)

🔬This is a nightly-only experimental API. (extend_one)
Extends a collection with exactly one element.
Source§

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. Read more
§

impl<K, V, S, A> FromIterator<(K, V)> for HashMap<K, V, S, A>
where K: Eq + Hash, S: BuildHasher + Default, A: Default + Allocator,

§

fn from_iter<T>(iter: T) -> HashMap<K, V, S, A>
where T: IntoIterator<Item = (K, V)>,

Creates a value from an iterator. Read more
§

impl<K, V, S> FromParallelIterator<(K, V)> for HashMap<K, V, S>
where K: Eq + Hash + Send, V: Send, S: BuildHasher + Default,

Collect (key, value) pairs from a parallel iterator into a hashmap. 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<P>(par_iter: P) -> HashMap<K, V, S>
where P: IntoParallelIterator<Item = (K, V)>,

Creates an instance of the collection from the parallel iterator par_iter. Read more
§

impl<K, Q, V, S, A> Index<&Q> for HashMap<K, V, S, A>
where K: Eq + Hash, Q: Hash + Equivalent<K> + ?Sized, S: BuildHasher, A: Allocator,

§

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 HashMap.

§Examples
use hashbrown::HashMap;

let map: HashMap<_, _> = [("a", "One"), ("b", "Two")].into();

assert_eq!(map[&"a"], "One");
assert_eq!(map[&"b"], "Two");
§

type Output = V

The returned type after indexing.
Source§

impl<K, V> InitHashMaps for HashMap<K, V, RandomState>

Source§

type HashMap = HashMap<K, V, RandomState>

Source§

fn new() -> <HashMap<K, V, RandomState> as InitHashMaps>::HashMap

Source§

fn with_capacity(capacity: usize) -> HashMap<K, V, RandomState>

§

impl<K, V, S, A> IntoIterator for HashMap<K, V, S, A>
where A: Allocator,

§

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

Creates a consuming iterator, that is, one that moves each key-value pair out of the map in arbitrary order. The map cannot be used after calling this.

§Examples
use hashbrown::HashMap;

let map: HashMap<_, _> = [("a", 1), ("b", 2), ("c", 3)].into();

// Not possible with .iter()
let mut vec: Vec<(&str, i32)> = map.into_iter().collect();
// The `IntoIter` iterator produces items in arbitrary order, so
// the items must be sorted to test them against a sorted array.
vec.sort_unstable();
assert_eq!(vec, [("a", 1), ("b", 2), ("c", 3)]);
§

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<K, V, S, A> IntoParallelIterator for HashMap<K, V, S, A>
where K: Send, V: Send, A: Allocator + Send,

§

type Item = (K, V)

The type of item that the parallel iterator will produce.
§

type Iter = IntoParIter<K, V, A>

The parallel iterator type that will be created.
§

fn into_par_iter(self) -> <HashMap<K, V, S, A> as IntoParallelIterator>::Iter

Converts self into a parallel iterator. Read more
§

impl<'a, K, V, S, A> ParallelExtend<(&'a K, &'a V)> for HashMap<K, V, S, A>
where K: Copy + Eq + Hash + Sync, V: Copy + Sync, S: BuildHasher, A: Allocator,

Extend a hash 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. Read more
§

impl<K, V, S, A> ParallelExtend<(K, V)> for HashMap<K, V, S, A>
where K: Eq + Hash + Send, V: Send, S: BuildHasher, A: Allocator,

Extend a hash 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. Read more
§

impl<K, V, S, A> PartialEq for HashMap<K, V, S, A>
where K: Eq + Hash, V: PartialEq, S: BuildHasher, A: Allocator,

§

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

Tests for self and other values to be equal, and is used by ==.
1.0.0 · Source§

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, H, A> Serialize for HashMap<K, V, H, A>
where K: Serialize + Eq + Hash, V: Serialize, H: BuildHasher, A: Allocator,

§

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. Read more
§

impl<K, V, S, A> Eq for HashMap<K, V, S, A>
where K: Eq + Hash, V: Eq, S: BuildHasher, A: Allocator,