Class LRUCache

Cache/LRUCache.js:1–144

class LRUCache {
  // 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) {
      throw new TypeError('Invalid capacity')
    }

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

    return Object.seal(this)
  }

  get info() {
    return Object.freeze({
      misses: this.misses,
      hits: this.hits,
      capacity: this.capacity,
      size: this.size
    })
  }

  get size() {
    return this.cache.size
  }

  get capacity() {
    return this.#capacity
  }

  set capacity(newCapacity) {
    if (newCapacity < 0) {
      throw new RangeError('Capacity should be greater than 0')
    }

    if (newCapacity < this.capacity) {
      let diff = 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)
  }