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							127 lines
						
					
					
						
							3.8 KiB
						
					
					
				
			
		
		
	
	
							127 lines
						
					
					
						
							3.8 KiB
						
					
					
				function _defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } }
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function _createClass(Constructor, protoProps, staticProps) { if (protoProps) _defineProperties(Constructor.prototype, protoProps); if (staticProps) _defineProperties(Constructor, staticProps); Object.defineProperty(Constructor, "prototype", { writable: false }); return Constructor; }
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function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }
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// https://medium.com/dsinjs/implementing-lru-cache-in-javascript-94ba6755cda9
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var Node = /*#__PURE__*/_createClass(function Node(key, value) {
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  var next = arguments.length > 2 && arguments[2] !== undefined ? arguments[2] : null;
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  var prev = arguments.length > 3 && arguments[3] !== undefined ? arguments[3] : null;
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  _classCallCheck(this, Node);
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  this.key = key;
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  this.value = value;
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  this.next = next;
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  this.prev = prev;
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});
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var LRUCache = /*#__PURE__*/function () {
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  //set default limit of 10 if limit is not passed.
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  function LRUCache() {
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    var limit = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : 10;
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    _classCallCheck(this, LRUCache);
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    this.size = 0;
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    this.limit = limit;
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    this.head = null;
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    this.tail = null;
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    this.cache = {};
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  } // Write Node to head of LinkedList
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  // update cache with Node key and Node reference
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  _createClass(LRUCache, [{
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    key: "put",
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    value: function put(key, value) {
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      this.ensureLimit();
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      if (!this.head) {
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        this.head = this.tail = new Node(key, value);
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      } else {
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        var node = new Node(key, value, this.head);
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        this.head.prev = node;
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        this.head = node;
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      } //Update the cache map
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      this.cache[key] = this.head;
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      this.size++;
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    } // Read from cache map and make that node as new Head of LinkedList
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  }, {
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    key: "get",
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    value: function get(key) {
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      if (this.cache[key]) {
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        var value = this.cache[key].value; // node removed from it's position and cache
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        this.remove(key); // write node again to the head of LinkedList to make it most recently used
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        this.put(key, value);
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        return value;
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      }
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      console.log("Item not available in cache for key ".concat(key));
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    }
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  }, {
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    key: "ensureLimit",
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    value: function ensureLimit() {
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      if (this.size === this.limit) {
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        this.remove(this.tail.key);
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      }
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    }
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  }, {
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    key: "remove",
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    value: function remove(key) {
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      var node = this.cache[key];
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      if (node.prev !== null) {
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        node.prev.next = node.next;
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      } else {
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        this.head = node.next;
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      }
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      if (node.next !== null) {
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        node.next.prev = node.prev;
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      } else {
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        this.tail = node.prev;
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      }
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      delete this.cache[key];
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      this.size--;
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    }
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  }, {
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    key: "clear",
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    value: function clear() {
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      this.head = null;
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      this.tail = null;
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      this.size = 0;
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      this.cache = {};
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    } // // Invokes the callback function with every node of the chain and the index of the node.
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    // forEach(fn) {
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    //   let node = this.head;
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    //   let counter = 0;
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    //   while (node) {
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    //     fn(node, counter);
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    //     node = node.next;
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    //     counter++;
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    //   }
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    // }
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    // // To iterate over LRU with a 'for...of' loop
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    // *[Symbol.iterator]() {
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    //   let node = this.head;
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    //   while (node) {
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    //     yield node;
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    //     node = node.next;
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    //   }
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    // }
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  }]);
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  return LRUCache;
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}();
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export { LRUCache as default };
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//# sourceMappingURL=LRUCache.js.map
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