JavaScript/Cache/LRUCache.js at master · flexycode/JavaScript · GitHub

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classLRUCache{
// LRU Cache to store a given capacity of data
 #capacity

/**
 * @param {number} capacity - the capacity of LRUCache
 * @returns {LRUCache} - sealed
 */
constructor(capacity){
if(!Number.isInteger(capacity)||capacity<0){
thrownewTypeError('Invalid capacity')
}

this.#capacity =~~capacity
this.misses=0
this.hits=0
this.cache=newMap()

returnObject.seal(this)
}

getinfo(){
returnObject.freeze({
misses: this.misses,
hits: this.hits,
capacity: this.capacity,
size: this.size
})
}

getsize(){
returnthis.cache.size
}

getcapacity(){
returnthis.#capacity
}

setcapacity(newCapacity){
if(newCapacity<0){
thrownewRangeError('Capacity should be greater than 0')
}

if(newCapacity<this.capacity){
letdiff=this.capacity-newCapacity

while(diff--){
this.#removeLeastRecentlyUsed()
}
}

this.#capacity =newCapacity
}

/**
 * delete oldest key existing in map by the help of iterator
 */
 #removeLeastRecentlyUsed(){
this.cache.delete(this.cache.keys().next().value)
}

/**
 * @param {string} key
 * @returns {*}
 */
has(key){
key=String(key)

returnthis.cache.has(key)
}

/**
 * @param {string} key
 * @param {*} value
 */
set(key,value){
key=String(key)
// Sets the value for the input key and if the key exists it updates the existing key
if(this.size===this.capacity){
this.#removeLeastRecentlyUsed()
}

this.cache.set(key,value)
}

/**
 * @param {string} key
 * @returns {*}
 */
get(key){
key=String(key)
// Returns the value for the input key. Returns null if key is not present in cache
if(this.cache.has(key)){
constvalue=this.cache.get(key)

// refresh the cache to update the order of key
this.cache.delete(key)
this.cache.set(key,value)

this.hits++
returnvalue
}

this.misses++
returnnull
}

/**
 * @param {JSON} json
 * @returns {LRUCache}
 */
parse(json){
const{ misses, hits, cache }=JSON.parse(json)

this.misses+=misses??0
this.hits+=hits??0

for(constkeyincache){
this.set(key,cache[key])
}

returnthis
}

/**
 * @param {number} indent
 * @returns {JSON} - string
 */
toString(indent){
constreplacer=(_,value)=>{
if(valueinstanceofSet){
return[...value]
}

if(valueinstanceofMap){
returnObject.fromEntries(value)
}

returnvalue
}

returnJSON.stringify(this,replacer,indent)
}
}

exportdefaultLRUCache