Struct lru::LruCache

pub struct LruCache<K, V> { /* fields omitted */ }

An LRU Cache

Methods

impl<K: Hash + Eq, V> LruCache<K, V>

fn new(cap: usize) -> LruCache<K, V>

Create a new LRU Cache that holds at most cap items.

Example

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

fn put(&mut self, k: K, v: V)

Put a key-value pair into cache. If the key already exists update its value.

Example

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

cache.put(1, "a");
cache.put(2, "b");
assert_eq!(cache.get(&1), Some(&"a"));
assert_eq!(cache.get(&2), Some(&"b"));

fn get<'a>(&'a mut self, k: &K) -> Option<&'a V>

Return the value corresponding to the key in the cache or None if it is not present in the cache. Moves the key to the head of the LRU list if it exists.

Example

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

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

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

fn peek<'a>(&'a self, k: &K) -> Option<&'a V>

Return the value corresponding to the key in the cache or None if it is not present in the cache. Unlike get, peek does not update the LRU list so key's position will be unchanged.

Example

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

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

assert_eq!(cache.peek(&1), Some(&"a"));
assert_eq!(cache.peek(&2), Some(&"b"));

fn contains(&self, k: &K) -> bool

Return a bool indicating whether the given key is in the cache. Does not update the LRU list.

Example

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

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

assert!(!cache.contains(&1));
assert!(cache.contains(&2));
assert!(cache.contains(&3));

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

Remove and return the value corresponding to the key from the cache or None if it does not exist.

Example

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

cache.put(2, "a");

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

fn len(&self) -> usize

Return the number of key-value pairs that are currently in the the cache.

Example

use lru::LruCache;
let mut cache = LruCache::new(2);
assert_eq!(cache.len(), 0);

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

cache.put(2, "b");
assert_eq!(cache.len(), 2);

cache.put(3, "c");
assert_eq!(cache.len(), 2);

fn cap(&self) -> usize

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

Example

use lru::LruCache;
let mut cache: LruCache<isize, &str> = LruCache::new(2);
assert_eq!(cache.cap(), 2);

Trait Implementations

impl<K, V> Drop for LruCache<K, V>

fn drop(&mut self)

A method called when the value goes out of scope.