Class FrequencyMap

Cache/LFUCache.js:12–49

// This frequency map class will act like javascript Map DS with more two custom method refresh & insert
class FrequencyMap extends Map {
  static get [Symbol.species]() {
    return Map
  } // for using Symbol.species we can access Map constructor  @see -> https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/@@species
  get [Symbol.toStringTag]() {
    return ''
  }

  /**
   * @method refresh
   * @description - It's revive a CacheNode, increment of this nodes frequency and refresh the frequencyMap via new incremented nodes frequency
   * @param {CacheNode} node
   */
  refresh(node) {
    const { frequency } = node
    const freqSet = this.get(frequency)
    freqSet.delete(node)

    node.frequency++

    this.insert(node)
  }

  /**
   * @method insert
   * @description - Add new CacheNode into HashSet by the frequency
   * @param {CacheNode} node
   */
  insert(node) {
    const { frequency } = node

    if (!this.has(frequency)) {
      this.set(frequency, new Set())
    }

    this.get(frequency).add(node)
  }
}

class LFUCache {
  #capacity