Struct linked_hash_map::LinkedHashMap

pub struct LinkedHashMap<K, V, S = RandomState> { /* fields omitted */ }

A linked hash map.

Methods

impl<K: Hash + Eq, V> LinkedHashMap<K, V>

fn new() -> Self

Creates a linked hash map.

fn with_capacity(capacity: usize) -> Self

Creates an empty linked hash map with the given initial capacity.

impl<K: Hash + Eq, V, S: BuildHasher> LinkedHashMap<K, V, S>

fn with_hasher(hash_builder: S) -> Self

Creates an empty linked hash map with the given initial hash builder.

fn with_capacity_and_hasher(capacity: usize, hash_builder: S) -> Self

Creates an empty linked hash map with the given initial capacity and hash builder.

fn reserve(&mut self, additional: usize)

Reserves capacity for at least additional more elements to be inserted into the map. The map may reserve more space to avoid frequent allocations.

Panics

Panics if the new allocation size overflows usize.

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.

fn entry(&mut self, k: K) -> Entry<K, V, S>

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

Examples

use linked_hash_map::LinkedHashMap;

let mut letters = LinkedHashMap::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);

fn entries(&mut self) -> Entries<K, V, S>

Returns an iterator visiting all entries in insertion order. Iterator element type is OccupiedEntry<K, V, S>. Allows for removal as well as replacing the entry.

Examples

use linked_hash_map::LinkedHashMap;

let mut map = LinkedHashMap::new();
map.insert("a", 10);
map.insert("c", 30);
map.insert("b", 20);

{
    let mut iter = map.entries();
    let mut entry = iter.next().unwrap();
    assert_eq!(&"a", entry.key());
    *entry.get_mut() = 17;
}

assert_eq!(&17, map.get(&"a").unwrap());

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

Inserts a key-value pair into the map. If the key already existed, the old value is returned.

Examples

use linked_hash_map::LinkedHashMap;
let mut map = LinkedHashMap::new();

map.insert(1, "a");
map.insert(2, "b");
assert_eq!(map[&1], "a");
assert_eq!(map[&2], "b");

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

Checks if the map contains the given key.

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

Returns the value corresponding to the key in the map.

Examples

use linked_hash_map::LinkedHashMap;
let mut map = LinkedHashMap::new();

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

assert_eq!(map.get(&1), Some(&"a"));
assert_eq!(map.get(&2), Some(&"c"));

fn get_mut<Q: ?Sized>(&mut self, k: &Q) -> Option<&mut V> where
    K: Borrow<Q>,
    Q: Eq + Hash, 

Returns the mutable reference corresponding to the key in the map.

Examples

use linked_hash_map::LinkedHashMap;
let mut map = LinkedHashMap::new();

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

*map.get_mut(&1).unwrap() = "c";
assert_eq!(map.get(&1), Some(&"c"));

fn get_refresh<Q: ?Sized>(&mut self, k: &Q) -> Option<&mut V> where
    K: Borrow<Q>,
    Q: Eq + Hash, 

Returns the value corresponding to the key in the map.

If value is found, it is moved to the end of the list. This operation can be used in implemenation of LRU cache.

Examples

use linked_hash_map::LinkedHashMap;
let mut map = LinkedHashMap::new();

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

assert_eq!(map.get_refresh(&2), Some(&mut "b"));

assert_eq!((&2, &"b"), map.iter().rev().next().unwrap());

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

Removes and returns the value corresponding to the key from the map.

Examples

use linked_hash_map::LinkedHashMap;
let mut map = LinkedHashMap::new();

map.insert(2, "a");

assert_eq!(map.remove(&1), None);
assert_eq!(map.remove(&2), Some("a"));
assert_eq!(map.remove(&2), None);
assert_eq!(map.len(), 0);

fn capacity(&self) -> usize

Returns the maximum number of key-value pairs the map can hold without reallocating.

Examples

use linked_hash_map::LinkedHashMap;
let mut map: LinkedHashMap<i32, &str> = LinkedHashMap::new();
let capacity = map.capacity();

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

Removes the first entry.

Can be used in implementation of LRU cache.

Examples

use linked_hash_map::LinkedHashMap;
let mut map = LinkedHashMap::new();
map.insert(1, 10);
map.insert(2, 20);
map.pop_front();
assert_eq!(map.get(&1), None);
assert_eq!(map.get(&2), Some(&20));

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

Gets the first entry.

Examples

use linked_hash_map::LinkedHashMap;
let mut map = LinkedHashMap::new();
map.insert(1, 10);
map.insert(2, 20);
assert_eq!(map.front(), Some((&1, &10)));

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

Removes the last entry.

Examples

use linked_hash_map::LinkedHashMap;
let mut map = LinkedHashMap::new();
map.insert(1, 10);
map.insert(2, 20);
map.pop_back();
assert_eq!(map.get(&1), Some(&10));
assert_eq!(map.get(&2), None);

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

Gets the last entry.

Examples

use linked_hash_map::LinkedHashMap;
let mut map = LinkedHashMap::new();
map.insert(1, 10);
map.insert(2, 20);
assert_eq!(map.back(), Some((&2, &20)));

fn len(&self) -> usize

Returns the number of key-value pairs in the map.

fn is_empty(&self) -> bool

Returns whether the map is currently empty.

fn hasher(&self) -> &S

Returns a reference to the map's hasher.

fn clear(&mut self)

Clears the map of all key-value pairs.

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

Returns a double-ended iterator visiting all key-value pairs in order of insertion. Iterator element type is (&'a K, &'a V)

Examples

use linked_hash_map::LinkedHashMap;

let mut map = LinkedHashMap::new();
map.insert("a", 10);
map.insert("c", 30);
map.insert("b", 20);

let mut iter = map.iter();
assert_eq!((&"a", &10), iter.next().unwrap());
assert_eq!((&"c", &30), iter.next().unwrap());
assert_eq!((&"b", &20), iter.next().unwrap());
assert_eq!(None, iter.next());

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

Returns a double-ended iterator visiting all key-value pairs in order of insertion. Iterator element type is (&'a K, &'a mut V)

Examples

use linked_hash_map::LinkedHashMap;

let mut map = LinkedHashMap::new();
map.insert("a", 10);
map.insert("c", 30);
map.insert("b", 20);

{
    let mut iter = map.iter_mut();
    let mut entry = iter.next().unwrap();
    assert_eq!(&"a", entry.0);
    *entry.1 = 17;
}

assert_eq!(&17, map.get(&"a").unwrap());

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

Returns a double-ended iterator visiting all key in order of insertion.

Examples

use linked_hash_map::LinkedHashMap;

let mut map = LinkedHashMap::new();
map.insert('a', 10);
map.insert('c', 30);
map.insert('b', 20);

let mut keys = map.keys();
assert_eq!(&'a', keys.next().unwrap());
assert_eq!(&'c', keys.next().unwrap());
assert_eq!(&'b', keys.next().unwrap());
assert_eq!(None, keys.next());

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

Returns a double-ended iterator visiting all values in order of insertion.

Examples

use linked_hash_map::LinkedHashMap;

let mut map = LinkedHashMap::new();
map.insert('a', 10);
map.insert('c', 30);
map.insert('b', 20);

let mut values = map.values();
assert_eq!(&10, values.next().unwrap());
assert_eq!(&30, values.next().unwrap());
assert_eq!(&20, values.next().unwrap());
assert_eq!(None, values.next());

Trait Implementations

impl<'a, K, V, S, Q: ?Sized> Index<&'a Q> for LinkedHashMap<K, V, S> where
    K: Hash + Eq + Borrow<Q>,
    S: BuildHasher,
    Q: Eq + Hash, 

type Output = V

The returned type after indexing

fn index(&self, index: &'a Q) -> &V

The method for the indexing (container[index]) operation

impl<'a, K, V, S, Q: ?Sized> IndexMut<&'a Q> for LinkedHashMap<K, V, S> where
    K: Hash + Eq + Borrow<Q>,
    S: BuildHasher,
    Q: Eq + Hash, 

fn index_mut(&mut self, index: &'a Q) -> &mut V

The method for the mutable indexing (container[index]) operation

impl<K: Hash + Eq + Clone, V: Clone, S: BuildHasher + Clone> Clone for LinkedHashMap<K, V, S>

fn clone(&self) -> Self

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<K: Hash + Eq, V, S: BuildHasher + Default> Default for LinkedHashMap<K, V, S>

fn default() -> Self

Returns the "default value" for a type.

impl<K: Hash + Eq, V, S: BuildHasher> Extend<(K, V)> for LinkedHashMap<K, V, S>

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

Extends a collection with the contents of an iterator.

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

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

Extends a collection with the contents of an iterator.

impl<K: Hash + Eq, V, S: BuildHasher + Default> FromIterator<(K, V)> for LinkedHashMap<K, V, S>

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

Creates a value from an iterator.

impl<A: Debug + Hash + Eq, B: Debug, S: BuildHasher> Debug for LinkedHashMap<A, B, S>

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

Returns a string that lists the key-value pairs in insertion order.

impl<K: Hash + Eq, V: PartialEq, S: BuildHasher> PartialEq for LinkedHashMap<K, V, S>

fn eq(&self, other: &Self) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<K: Hash + Eq, V: Eq, S: BuildHasher> Eq for LinkedHashMap<K, V, S>

impl<K: Hash + Eq + PartialOrd, V: PartialOrd, S: BuildHasher> PartialOrd for LinkedHashMap<K, V, S>

fn partial_cmp(&self, other: &Self) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Self) -> bool

This method tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Self) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

fn ge(&self, other: &Self) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

fn gt(&self, other: &Self) -> bool

This method tests greater than (for self and other) and is used by the > operator.

impl<K: Hash + Eq + Ord, V: Ord, S: BuildHasher> Ord for LinkedHashMap<K, V, S>

fn cmp(&self, other: &Self) -> Ordering

This method returns an Ordering between self and other.

impl<K: Hash + Eq, V: Hash, S: BuildHasher> Hash for LinkedHashMap<K, V, S>

fn hash<H: Hasher>(&self, h: &mut H)

Feeds this value into the given [Hasher].

fn hash_slice<H>(data: &[Self], state: &mut H) where
    H: Hasher, 

Feeds a slice of this type into the given [Hasher].

impl<K: Send, V: Send, S: Send> Send for LinkedHashMap<K, V, S>

impl<K: Sync, V: Sync, S: Sync> Sync for LinkedHashMap<K, V, S>

impl<K, V, S> Drop for LinkedHashMap<K, V, S>

fn drop(&mut self)

A method called when the value goes out of scope.

impl<'a, K: Hash + Eq, V, S: BuildHasher> IntoIterator for &'a LinkedHashMap<K, V, S>

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

The type of the elements being iterated over.

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

Which kind of iterator are we turning this into?

fn into_iter(self) -> Iter<'a, K, V>

Creates an iterator from a value.

impl<'a, K: Hash + Eq, V, S: BuildHasher> IntoIterator for &'a mut LinkedHashMap<K, V, S>

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

The type of the elements being iterated over.

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

Which kind of iterator are we turning this into?

fn into_iter(self) -> IterMut<'a, K, V>

Creates an iterator from a value.

impl<K: Hash + Eq, V, S: BuildHasher> IntoIterator for LinkedHashMap<K, V, S>

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?

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

Creates an iterator from a value.