Type Alias SeenTees

pub type SeenTees = HashMap<*const RefCell<HydroNode>, Rc<RefCell<HydroNode>>>;

Aliased Type

struct SeenTees { /* private fields */ }

Implementations

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

pub fn new() -> HashMap<K, V>

Creates an empty HashMap.

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

Examples

use std::collections::HashMap;
let mut map: HashMap<&str, i32> = HashMap::new();

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

Creates an empty HashMap with at least the specified capacity.

The hash map will be able to hold at least capacity elements without reallocating. This method is allowed to allocate for more elements than capacity. If capacity is zero, the hash map will not allocate.

Examples

use std::collections::HashMap;
let mut map: HashMap<&str, i32> = HashMap::with_capacity(10);

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

where S: BuildHasher,

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

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

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 initialize 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).

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

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

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.

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

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

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

The created map has the default initial capacity.

Warning: hash_builder is normally randomly generated, and is designed to allow HashMaps to be resistant to attacks that cause many collisions and very poor performance. Setting it manually using this function can expose a DoS attack vector.

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

Examples

use std::collections::HashMap;
use std::hash::RandomState;

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

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

Creates an empty HashMap with at least the specified capacity, using hasher to hash the keys.

The hash map will be able to hold at least capacity elements without reallocating. This method is allowed to allocate for more elements than capacity. If capacity is zero, the hash map will not allocate.

Warning: hasher is normally randomly generated, and is designed to allow HashMaps to be resistant to attacks that cause many collisions and very poor performance. Setting it manually using this function can expose a DoS attack vector.

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

Examples

use std::collections::HashMap;
use std::hash::RandomState;

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

pub fn capacity(&self) -> usize

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 std::collections::HashMap;
let map: HashMap<i32, i32> = HashMap::with_capacity(100);
assert!(map.capacity() >= 100);

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

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

Examples

use std::collections::HashMap;

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

for key in map.keys() {
    println!("{key}");
}

Performance

In the current implementation, iterating over keys takes O(capacity) time instead of O(len) because it internally visits empty buckets too.

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

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 std::collections::HashMap;

let map = HashMap::from([
    ("a", 1),
    ("b", 2),
    ("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"]);

Performance

In the current implementation, iterating over keys takes O(capacity) time instead of O(len) because it internally visits empty buckets too.

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

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

Examples

use std::collections::HashMap;

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

for val in map.values() {
    println!("{val}");
}

Performance

In the current implementation, iterating over values takes O(capacity) time instead of O(len) because it internally visits empty buckets too.

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

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

Examples

use std::collections::HashMap;

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

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

for val in map.values() {
    println!("{val}");
}

Performance

In the current implementation, iterating over values takes O(capacity) time instead of O(len) because it internally visits empty buckets too.

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

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 std::collections::HashMap;

let map = HashMap::from([
    ("a", 1),
    ("b", 2),
    ("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]);

Performance

In the current implementation, iterating over values takes O(capacity) time instead of O(len) because it internally visits empty buckets too.

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

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

Examples

use std::collections::HashMap;

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

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

Performance

In the current implementation, iterating over map takes O(capacity) time instead of O(len) because it internally visits empty buckets too.

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

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 std::collections::HashMap;

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

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

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

Performance

In the current implementation, iterating over map takes O(capacity) time instead of O(len) because it internally visits empty buckets too.

pub fn len(&self) -> usize

Returns the number of elements in the map.

Examples

use std::collections::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

Returns true if the map contains no elements.

Examples

use std::collections::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>

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 map to optimize its implementation.

Examples

use std::collections::HashMap;

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

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

assert!(a.is_empty());

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

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

Creates an iterator which 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.

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.

Examples

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

use std::collections::HashMap;

let mut map: HashMap<i32, i32> = (0..8).map(|x| (x, x)).collect();
let extracted: HashMap<i32, i32> = map.extract_if(|k, _v| k % 2 == 0).collect();

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

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

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

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

Retains only the elements specified by the predicate.

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

Examples

use std::collections::HashMap;

let mut map: HashMap<i32, i32> = (0..8).map(|x| (x, x*10)).collect();
map.retain(|&k, _| k % 2 == 0);
assert_eq!(map.len(), 4);

Performance

In the current implementation, this operation takes O(capacity) time instead of O(len) because it internally visits empty buckets too.

pub fn clear(&mut self)

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

Examples

use std::collections::HashMap;

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

pub fn hasher(&self) -> &S

Returns a reference to the map’s BuildHasher.

Examples

use std::collections::HashMap;
use std::hash::RandomState;

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

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

where K: Eq + Hash, S: BuildHasher,

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

Reserves capacity for at least additional more elements to be inserted in the HashMap. The collection may reserve more space to speculatively avoid frequent reallocations. After calling reserve, capacity will be greater than or equal to self.len() + additional. Does nothing if capacity is already sufficient.

Panics

Panics if the new allocation size overflows usize.

Examples

use std::collections::HashMap;
let mut map: HashMap<&str, i32> = HashMap::new();
map.reserve(10);

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

Tries to reserve capacity for at least additional more elements to be inserted in the HashMap. The collection may reserve more space to speculatively avoid frequent reallocations. After calling try_reserve, capacity will be greater than or equal to self.len() + additional if it returns Ok(()). Does nothing if capacity is already sufficient.

Errors

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

Examples

use std::collections::HashMap;

let mut map: HashMap<&str, isize> = HashMap::new();
map.try_reserve(10).expect("why is the test harness OOMing on a handful of bytes?");

pub fn shrink_to_fit(&mut self)

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 std::collections::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)

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.

If the current capacity is less than the lower limit, this is a no-op.

Examples

use std::collections::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);

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

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

Examples

use std::collections::HashMap;

let mut letters = HashMap::new();

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

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

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

where K: Borrow<Q>, Q: Hash + Eq + ?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 Hash and Eq on the borrowed form must match those for the key type.

Examples

use std::collections::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 K: Borrow<Q>, Q: Hash + Eq + ?Sized,

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

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

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

Examples

use std::collections::HashMap;
use std::hash::{Hash, Hasher};

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

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

impl Eq for S {}

impl Hash for S {
    fn hash<H: Hasher>(&self, state: &mut H) {
        self.id.hash(state);
    }
}

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 = HashMap::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 get_disjoint_mut<Q, const N: usize>( &mut self, ks: [&Q; N], ) -> [Option<&mut V>; N]

where K: Borrow<Q>, Q: Hash + Eq + ?Sized,

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 std::collections::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_disjoint_mut([
    "Athenæum",
    "Bodleian Library",
]) else { panic!() };

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

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

use std::collections::HashMap;

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

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

pub unsafe fn get_disjoint_unchecked_mut<Q, const N: usize>( &mut self, ks: [&Q; N], ) -> [Option<&mut V>; N]

where K: Borrow<Q>, Q: Hash + Eq + ?Sized,

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_disjoint_mut.

Safety

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

Examples

use std::collections::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_disjoint_unchecked_mut([
    "Athenæum",
    "Bodleian Library",
]) }) else { panic!() };

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

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

where K: Borrow<Q>, Q: Hash + Eq + ?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 Hash and Eq on the borrowed form must match those for the key type.

Examples

use std::collections::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 K: Borrow<Q>, Q: Hash + Eq + ?Sized,

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

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

Examples

use std::collections::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");

pub fn insert(&mut self, k: K, v: 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

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

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

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

Basic usage:

#![feature(map_try_insert)]

use std::collections::HashMap;

let mut map = HashMap::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, k: &Q) -> Option<V>

where K: Borrow<Q>, Q: Hash + Eq + ?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 Hash and Eq on the borrowed form must match those for the key type.

Examples

use std::collections::HashMap;

let mut map = HashMap::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, k: &Q) -> Option<(K, V)>

where K: Borrow<Q>, Q: Hash + Eq + ?Sized,

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

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

Examples

use std::collections::HashMap;

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

Trait Implementations

impl<K, V, S> Accumulate<(K, V)> for HashMap<K, V, S>

where K: Eq + Hash, S: BuildHasher + Default,

fn initial(capacity: Option<usize>) -> HashMap<K, V, S>

Create a new Extend of the correct type

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

Accumulate the input into an accumulator

impl<K, V, S> Accumulate<(K, V)> for HashMap<K, V, S>

where K: Eq + Hash, S: BuildHasher + Default,

fn initial(capacity: Option<usize>) -> HashMap<K, V, S>

Create a new Extend of the correct type

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

Accumulate the input into an accumulator

impl<K, V> Clear for HashMap<K, V>

fn clear(&mut self)

Remove all the elements of the collection.

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

fn clear(&mut self)

Clears the collection without neccesarily freeing allocations.

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

where K: Clone, V: Clone, S: Clone,

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

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<K, V> Collection for HashMap<K, V>

type Item = V

Type of the items of the collection.

impl<K, V> CollectionMut for HashMap<K, V>

type ItemMut<'a> = &'a mut V where HashMap<K, V>: 'a

Type of mutable references to items of the collection.

fn upcast_item_mut<'short, 'long>( r: <HashMap<K, V> as CollectionMut>::ItemMut<'long>, ) -> <HashMap<K, V> as CollectionMut>::ItemMut<'short>

where 'long: 'short, HashMap<K, V>: 'long,

Changes an item mutable reference into a shorter lived mutable reference.

impl<K, V> CollectionRef for HashMap<K, V>

type ItemRef<'a> = &'a V where HashMap<K, V>: 'a

Type of references to items of the collection.

fn upcast_item_ref<'short, 'long>( r: <HashMap<K, V> as CollectionRef>::ItemRef<'long>, ) -> <HashMap<K, V> as CollectionRef>::ItemRef<'short>

where 'long: 'short, HashMap<K, V>: 'long,

Changes an item reference into a shorter lived reference.

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

where K: Debug, V: Debug,

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

Formats the value using the given formatter.

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

where S: Default,

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

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

impl<'de, K, V, S> Deserialize<'de> for HashMap<K, V, S>

where K: Deserialize<'de> + Eq + Hash, V: Deserialize<'de>, S: BuildHasher + Default,

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

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<'a, K, V, S> Extend<(&'a K, &'a V)> for HashMap<K, V, S>

where K: Eq + Hash + Copy, V: Copy, S: BuildHasher,

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

where T: 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, S> Extend<(K, V)> for HashMap<K, V, S>

where K: Eq + Hash, S: BuildHasher,

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)>,

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 HashMap<K, V>

where K: Eq + Hash,

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

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

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

Examples

use std::collections::HashMap;

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

impl<K, V, S> FromIterator<(K, V)> for HashMap<K, V, S>

where K: Eq + Hash, S: BuildHasher + Default,

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

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

Constructs a HashMap<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<'source, K, V, S> FromPyObject<'source> for HashMap<K, V, S>

where K: FromPyObject<'source> + Eq + Hash, V: FromPyObject<'source>, S: BuildHasher + Default,

fn extract(ob: &'source PyAny) -> Result<HashMap<K, V, S>, PyErr>

Extracts Self from the source PyObject.

impl<'a, Q, K, V> Get<&'a Q> for HashMap<K, V>

where K: Hash + Eq + Borrow<Q>, Q: Hash + Eq + ?Sized,

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

Returns a reference to the item stored behind the given key (if any).

fn contains(&self, key: T) -> bool

Checks if the collection contains an item behind the given key.

impl<'a, Q, K, V> GetKeyValue<&'a Q> for HashMap<K, V>

where K: Hash + Eq + Borrow<Q>, Q: Hash + Eq + ?Sized,

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

Returns the key-value pair matching the given key.

impl<'a, Q, K, V> GetMut<&'a Q> for HashMap<K, V>

where K: Hash + Eq + Borrow<Q>, Q: Hash + Eq + ?Sized,

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

Returns a mutable reference to the item stored behind the given key (if any).

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

where S: BuildHasher + Default,

fn new() -> HashMap<K, V, S>

Constructs a new HashMap

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

Constructs a new HashMap with a given initial capacity

impl<K, Q, V, S> Index<&Q> for HashMap<K, V, S>

where K: Eq + Hash + Borrow<Q>, Q: Eq + Hash + ?Sized, S: BuildHasher,

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.

type Output = V

The returned type after indexing.

impl<'de, K, V, S, E> IntoDeserializer<'de, E> for HashMap<K, V, S>

where K: IntoDeserializer<'de, E> + Eq + Hash, V: IntoDeserializer<'de, E>, S: BuildHasher, E: Error,

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

The type of the deserializer being converted into.

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

Convert this value into a deserializer.

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

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

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 std::collections::HashMap;

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

// Not possible with .iter()
let vec: Vec<(&str, i32)> = map.into_iter().collect();

type Item = (K, V)

The type of the elements being iterated over.

type IntoIter = IntoIter<K, V>

Which kind of iterator are we turning this into?

impl<K, V, H> IntoPy<Py<PyAny>> for HashMap<K, V, H>

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

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

Performs the conversion.

impl<K, V> Iter for HashMap<K, V>

type Iter<'a> = Values<'a, K, V> where HashMap<K, V>: 'a

Iterator type.

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

Create an iterator over the items of the collection.

impl<K, V> Keyed for HashMap<K, V>

type Key = K

Type of the keys indexing each item of the collection.

impl<K, V> KeyedRef for HashMap<K, V>

type KeyRef<'a> = &'a K where HashMap<K, V>: 'a

Type of references to keys of the collection.

fn upcast_key_ref<'short, 'long>( r: <HashMap<K, V> as KeyedRef>::KeyRef<'long>, ) -> <HashMap<K, V> as KeyedRef>::KeyRef<'short>

where 'long: 'short, HashMap<K, V>: 'long,

Changes a key reference into a shorter lived reference.

impl<K, V> Len for HashMap<K, V>

fn len(&self) -> usize

Returns the number of elements in the collection.

fn is_empty(&self) -> bool

Checks if the collection is empty.

impl<K, V> MapInsert<K> for HashMap<K, V>

where K: Hash + Eq,

type Output = Option<V>

The output of the insertion function.

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

Insert a new key-value pair in the collection.

impl<K, V> MapIter for HashMap<K, V>

type Iter<'a> = Iter<'a, K, V> where HashMap<K, V>: 'a

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

impl<K, V> MapIterMut for HashMap<K, V>

type IterMut<'a> = IterMut<'a, K, V> where HashMap<K, V>: 'a

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

impl<Key, OldVal> MapMapValues<OldVal> for HashMap<Key, OldVal>

where Key: Eq + Hash,

type MapValue<NewVal> = HashMap<Key, NewVal>

Output type, should be Self but with OldVal replaced with NewVal.

fn map_values<NewVal, MapFn>( self, map_fn: MapFn, ) -> <HashMap<Key, OldVal> as MapMapValues<OldVal>>::MapValue<NewVal>

where MapFn: FnMut(OldVal) -> NewVal,

Map the values into using the map_fn.

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

where K: Eq + Hash, V: PartialEq, S: BuildHasher,

fn eq(&self, other: &HashMap<K, V, S>) -> 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<'a, Q, K, V> Remove<&'a Q> for HashMap<K, V>

where K: Hash + Eq + Borrow<Q>, Q: Hash + Eq + ?Sized,

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

Remove the element identified by the given key.

impl<K, V, H> Serialize for HashMap<K, V, H>

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> SimpleCollectionMut for HashMap<K, V>

fn into_mut<'r>( r: <HashMap<K, V> as CollectionMut>::ItemMut<'r>, ) -> &'r mut <HashMap<K, V> as Collection>::Item

where HashMap<K, V>: 'r,

impl<K, V> SimpleCollectionRef for HashMap<K, V>

fn into_ref<'r>( r: <HashMap<K, V> as CollectionRef>::ItemRef<'r>, ) -> &'r <HashMap<K, V> as Collection>::Item

where HashMap<K, V>: 'r,

impl<K, V> SimpleKeyedRef for HashMap<K, V>

fn into_ref<'r>( r: <HashMap<K, V> as KeyedRef>::KeyRef<'r>, ) -> &'r <HashMap<K, V> as Keyed>::Key

where HashMap<K, V>: 'r,

impl<K, V, H> ToPyObject for HashMap<K, V, H>

where K: Hash + Eq + ToPyObject, V: ToPyObject, H: BuildHasher,

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

Converts self into a Python object.

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

where K: Eq + Hash, V: Eq, S: BuildHasher,

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

where K: UnwindSafe, V: UnwindSafe, S: UnwindSafe,