merge: Improved LRUCache (#953)

* feat: added new validation test casses & methods

* style: formated with standard

* feat: added parse method & test cases

* docs: added js docs

* chore: added default import export

Cache/LRUCache.js

@@ -1,40 +1,146 @@
 class LRUCache {
   // LRU Cache to store a given capacity of data
+  #capacity
+
+  /**
+   * @param {number} capacity - the capacity of LRUCache
+   * @returns {LRUCache} - sealed
+   */
   constructor (capacity) {
-    this.cache = new Map()
-    this.capacity = capacity
-    this.hits = 0
-    this.miss = 0
-  }
-
-  cacheInfo () {
-    // Return the details for the cache instance [hits, misses, capacity, current_size]
-    return `CacheInfo(hits=${this.hits}, misses=${this.miss}, capacity=${this.capacity}, current size=${this.cache.size})`
-  }
-
-  set (key, value) {
-    // Sets the value for the input key and if the key exists it updates the existing key
-    if (this.cache.size === this.capacity) {
-      // delete oldest key existing in map
-      this.cache.delete(this.cache.keys().next().value)
+    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)
+  }
+
+  /**
+   * @param {string} key
+   * @returns {*}
+   */
+  has (key) {
+    key = String(key)
+
+    return this.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)) {
       const value = this.cache.get(key)
+
       // refresh the cache to update the order of key
       this.cache.delete(key)
       this.cache.set(key, value)
-      this.hits += 1
+
+      this.hits++
       return value
-    } else {
-      this.miss += 1
-      return null
     }
+
+    this.misses++
+    return null
+  }
+
+  /**
+   * @param {JSON} json
+   * @returns {LRUCache}
+   */
+  parse (json) {
+    const { misses, hits, cache } = JSON.parse(json)
+
+    this.misses += misses ?? 0
+    this.hits += hits ?? 0
+
+    for (const key in cache) {
+      this.set(key, cache[key])
+    }
+
+    return this
+  }
+
+  /**
+   * @param {number} indent
+   * @returns {JSON} - string
+   */
+  toString (indent) {
+    const replacer = (_, value) => {
+      if (value instanceof Set) {
+        return [...value]
+      }
+
+      if (value instanceof Map) {
+        return Object.fromEntries(value)
+      }
+
+      return value
+    }
+
+    return JSON.stringify(this, replacer, indent)
   }
 }
 
-export { LRUCache }
+export default LRUCache