Struct lru_cache::LruCache

pub struct LruCache<K: Eq + Hash, V, S: BuildHasher = RandomState> { /* fields omitted */ }

An LRU cache.

Methods

impl<K: Eq + Hash, V> LruCache<K, V>

fn new(capacity: usize) -> Self

Creates an empty cache that can hold at most capacity items.

Examples

use lru_cache::LruCache;
let mut cache: LruCache<i32, &str> = LruCache::new(10);

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

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

Creates an empty cache that can hold at most capacity items with the given hash builder.

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

Checks if the map contains the given key.

Examples

use lru_cache::LruCache;

let mut cache = LruCache::new(1);

cache.insert(1, "a");
assert_eq!(cache.contains_key(&1), true);

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

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

Examples

use lru_cache::LruCache;

let mut cache = LruCache::new(2);

cache.insert(1, "a");
cache.insert(2, "b");
assert_eq!(cache.get_mut(&1), Some(&mut "a"));
assert_eq!(cache.get_mut(&2), Some(&mut "b"));

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

Returns a mutable reference to the value corresponding to the given key in the cache, if any.

Examples

use lru_cache::LruCache;

let mut cache = LruCache::new(2);

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

assert_eq!(cache.get_mut(&1), None);
assert_eq!(cache.get_mut(&2), Some(&mut "c"));

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

Removes the given key from the cache and returns its corresponding value.

Examples

use lru_cache::LruCache;

let mut cache = LruCache::new(2);

cache.insert(2, "a");

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

fn capacity(&self) -> usize

Returns the maximum number of key-value pairs the cache can hold.

Examples

use lru_cache::LruCache;
let mut cache: LruCache<i32, &str> = LruCache::new(2);
assert_eq!(cache.capacity(), 2);

fn set_capacity(&mut self, capacity: usize)

Sets the number of key-value pairs the cache can hold. Removes least-recently-used key-value pairs if necessary.

Examples

use lru_cache::LruCache;

let mut cache = LruCache::new(2);

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

assert_eq!(cache.get_mut(&1), None);
assert_eq!(cache.get_mut(&2), Some(&mut "b"));
assert_eq!(cache.get_mut(&3), Some(&mut "c"));

cache.set_capacity(3);
cache.insert(1, "a");
cache.insert(2, "b");

assert_eq!(cache.get_mut(&1), Some(&mut "a"));
assert_eq!(cache.get_mut(&2), Some(&mut "b"));
assert_eq!(cache.get_mut(&3), Some(&mut "c"));

cache.set_capacity(1);

assert_eq!(cache.get_mut(&1), None);
assert_eq!(cache.get_mut(&2), None);
assert_eq!(cache.get_mut(&3), Some(&mut "c"));

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

Removes and returns the least recently used key-value pair as a tuple.

Examples

use lru_cache::LruCache;

let mut cache = LruCache::new(2);

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

assert_eq!(cache.remove_lru(), Some((1, "a")));
assert_eq!(cache.len(), 1);

fn len(&self) -> usize

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

fn is_empty(&self) -> bool

Returns true if the cache contains no key-value pairs.

fn clear(&mut self)

Removes all key-value pairs from the cache.

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

Returns an iterator over the cache's key-value pairs in least- to most-recently-used order.

Accessing the cache through the iterator does not affect the cache's LRU state.

Examples

use lru_cache::LruCache;

let mut cache = LruCache::new(2);

cache.insert(1, 10);
cache.insert(2, 20);
cache.insert(3, 30);

let kvs: Vec<_> = cache.iter().collect();
assert_eq!(kvs, [(&2, &20), (&3, &30)]);

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

Returns an iterator over the cache's key-value pairs in least- to most-recently-used order, with mutable references to the values.

Accessing the cache through the iterator does not affect the cache's LRU state.

Examples

use lru_cache::LruCache;

let mut cache = LruCache::new(2);

cache.insert(1, 10);
cache.insert(2, 20);
cache.insert(3, 30);

let mut n = 2;

for (k, v) in cache.iter_mut() {
    assert_eq!(*k, n);
    assert_eq!(*v, n * 10);
    *v *= 10;
    n += 1;
}

assert_eq!(n, 4);
assert_eq!(cache.get_mut(&2), Some(&mut 200));
assert_eq!(cache.get_mut(&3), Some(&mut 300));

Trait Implementations

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

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

Returns a copy of the value.

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

Performs copy-assignment from source.

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

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

Extends a collection with the contents of an iterator.

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

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

Formats the value using the given formatter.

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

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