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					134 lines
				
				3.9 KiB
			
		
		
			
		
	
	
					134 lines
				
				3.9 KiB
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											3 years ago
										 
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								"use strict";
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								Object.defineProperty(exports, "__esModule", {
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								  value: true
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								});
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								exports["default"] = void 0;
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								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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								exports["default"] = LRUCache;
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								//# sourceMappingURL=LRUCache.js.map
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