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334 lines
8.0 KiB
334 lines
8.0 KiB
;(function () { // closure for web browsers |
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if (typeof module === 'object' && module.exports) { |
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module.exports = LRUCache |
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} else { |
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// just set the global for non-node platforms. |
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this.LRUCache = LRUCache |
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} |
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function hOP (obj, key) { |
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return Object.prototype.hasOwnProperty.call(obj, key) |
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} |
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function naiveLength () { return 1 } |
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var didTypeWarning = false |
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function typeCheckKey(key) { |
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if (!didTypeWarning && typeof key !== 'string' && typeof key !== 'number') { |
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didTypeWarning = true |
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console.error(new TypeError("LRU: key must be a string or number. Almost certainly a bug! " + typeof key).stack) |
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} |
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} |
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function LRUCache (options) { |
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if (!(this instanceof LRUCache)) |
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return new LRUCache(options) |
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if (typeof options === 'number') |
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options = { max: options } |
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if (!options) |
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options = {} |
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this._max = options.max |
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// Kind of weird to have a default max of Infinity, but oh well. |
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if (!this._max || !(typeof this._max === "number") || this._max <= 0 ) |
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this._max = Infinity |
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this._lengthCalculator = options.length || naiveLength |
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if (typeof this._lengthCalculator !== "function") |
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this._lengthCalculator = naiveLength |
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this._allowStale = options.stale || false |
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this._maxAge = options.maxAge || null |
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this._dispose = options.dispose |
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this.reset() |
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} |
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// resize the cache when the max changes. |
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Object.defineProperty(LRUCache.prototype, "max", |
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{ set : function (mL) { |
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if (!mL || !(typeof mL === "number") || mL <= 0 ) mL = Infinity |
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this._max = mL |
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if (this._length > this._max) trim(this) |
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} |
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, get : function () { return this._max } |
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, enumerable : true |
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}) |
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// resize the cache when the lengthCalculator changes. |
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Object.defineProperty(LRUCache.prototype, "lengthCalculator", |
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{ set : function (lC) { |
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if (typeof lC !== "function") { |
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this._lengthCalculator = naiveLength |
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this._length = this._itemCount |
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for (var key in this._cache) { |
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this._cache[key].length = 1 |
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} |
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} else { |
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this._lengthCalculator = lC |
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this._length = 0 |
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for (var key in this._cache) { |
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this._cache[key].length = this._lengthCalculator(this._cache[key].value) |
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this._length += this._cache[key].length |
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} |
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} |
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if (this._length > this._max) trim(this) |
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} |
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, get : function () { return this._lengthCalculator } |
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, enumerable : true |
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}) |
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Object.defineProperty(LRUCache.prototype, "length", |
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{ get : function () { return this._length } |
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, enumerable : true |
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}) |
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Object.defineProperty(LRUCache.prototype, "itemCount", |
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{ get : function () { return this._itemCount } |
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, enumerable : true |
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}) |
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LRUCache.prototype.forEach = function (fn, thisp) { |
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thisp = thisp || this |
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var i = 0 |
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var itemCount = this._itemCount |
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for (var k = this._mru - 1; k >= 0 && i < itemCount; k--) if (this._lruList[k]) { |
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i++ |
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var hit = this._lruList[k] |
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if (isStale(this, hit)) { |
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del(this, hit) |
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if (!this._allowStale) hit = undefined |
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} |
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if (hit) { |
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fn.call(thisp, hit.value, hit.key, this) |
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} |
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} |
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} |
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LRUCache.prototype.keys = function () { |
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var keys = new Array(this._itemCount) |
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var i = 0 |
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for (var k = this._mru - 1; k >= 0 && i < this._itemCount; k--) if (this._lruList[k]) { |
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var hit = this._lruList[k] |
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keys[i++] = hit.key |
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} |
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return keys |
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} |
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LRUCache.prototype.values = function () { |
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var values = new Array(this._itemCount) |
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var i = 0 |
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for (var k = this._mru - 1; k >= 0 && i < this._itemCount; k--) if (this._lruList[k]) { |
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var hit = this._lruList[k] |
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values[i++] = hit.value |
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} |
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return values |
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} |
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LRUCache.prototype.reset = function () { |
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if (this._dispose && this._cache) { |
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for (var k in this._cache) { |
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this._dispose(k, this._cache[k].value) |
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} |
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} |
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this._cache = Object.create(null) // hash of items by key |
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this._lruList = Object.create(null) // list of items in order of use recency |
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this._mru = 0 // most recently used |
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this._lru = 0 // least recently used |
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this._length = 0 // number of items in the list |
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this._itemCount = 0 |
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} |
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LRUCache.prototype.dump = function () { |
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var arr = [] |
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var i = 0 |
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for (var k = this._mru - 1; k >= 0 && i < this._itemCount; k--) if (this._lruList[k]) { |
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var hit = this._lruList[k] |
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if (!isStale(this, hit)) { |
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//Do not store staled hits |
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++i |
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arr.push({ |
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k: hit.key, |
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v: hit.value, |
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e: hit.now + (hit.maxAge || 0) |
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}); |
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} |
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} |
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//arr has the most read first |
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return arr |
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} |
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LRUCache.prototype.dumpLru = function () { |
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return this._lruList |
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} |
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LRUCache.prototype.set = function (key, value, maxAge) { |
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maxAge = maxAge || this._maxAge |
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typeCheckKey(key) |
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var now = maxAge ? Date.now() : 0 |
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var len = this._lengthCalculator(value) |
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if (hOP(this._cache, key)) { |
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if (len > this._max) { |
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del(this, this._cache[key]) |
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return false |
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} |
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// dispose of the old one before overwriting |
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if (this._dispose) |
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this._dispose(key, this._cache[key].value) |
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this._cache[key].now = now |
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this._cache[key].maxAge = maxAge |
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this._cache[key].value = value |
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this._length += (len - this._cache[key].length) |
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this._cache[key].length = len |
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this.get(key) |
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if (this._length > this._max) |
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trim(this) |
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return true |
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} |
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var hit = new Entry(key, value, this._mru++, len, now, maxAge) |
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// oversized objects fall out of cache automatically. |
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if (hit.length > this._max) { |
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if (this._dispose) this._dispose(key, value) |
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return false |
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} |
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this._length += hit.length |
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this._lruList[hit.lu] = this._cache[key] = hit |
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this._itemCount ++ |
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if (this._length > this._max) |
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trim(this) |
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return true |
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} |
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LRUCache.prototype.has = function (key) { |
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typeCheckKey(key) |
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if (!hOP(this._cache, key)) return false |
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var hit = this._cache[key] |
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if (isStale(this, hit)) { |
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return false |
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} |
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return true |
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} |
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LRUCache.prototype.get = function (key) { |
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typeCheckKey(key) |
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return get(this, key, true) |
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} |
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LRUCache.prototype.peek = function (key) { |
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typeCheckKey(key) |
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return get(this, key, false) |
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} |
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LRUCache.prototype.pop = function () { |
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var hit = this._lruList[this._lru] |
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del(this, hit) |
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return hit || null |
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} |
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LRUCache.prototype.del = function (key) { |
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typeCheckKey(key) |
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del(this, this._cache[key]) |
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} |
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LRUCache.prototype.load = function (arr) { |
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//reset the cache |
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this.reset(); |
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var now = Date.now() |
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//A previous serialized cache has the most recent items first |
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for (var l = arr.length - 1; l >= 0; l-- ) { |
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var hit = arr[l] |
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typeCheckKey(hit.k) |
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var expiresAt = hit.e || 0 |
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if (expiresAt === 0) { |
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//the item was created without expiration in a non aged cache |
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this.set(hit.k, hit.v) |
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} else { |
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var maxAge = expiresAt - now |
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//dont add already expired items |
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if (maxAge > 0) this.set(hit.k, hit.v, maxAge) |
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} |
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} |
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} |
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function get (self, key, doUse) { |
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typeCheckKey(key) |
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var hit = self._cache[key] |
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if (hit) { |
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if (isStale(self, hit)) { |
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del(self, hit) |
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if (!self._allowStale) hit = undefined |
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} else { |
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if (doUse) use(self, hit) |
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} |
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if (hit) hit = hit.value |
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} |
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return hit |
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} |
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function isStale(self, hit) { |
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if (!hit || (!hit.maxAge && !self._maxAge)) return false |
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var stale = false; |
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var diff = Date.now() - hit.now |
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if (hit.maxAge) { |
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stale = diff > hit.maxAge |
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} else { |
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stale = self._maxAge && (diff > self._maxAge) |
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} |
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return stale; |
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} |
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function use (self, hit) { |
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shiftLU(self, hit) |
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hit.lu = self._mru ++ |
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self._lruList[hit.lu] = hit |
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} |
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function trim (self) { |
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while (self._lru < self._mru && self._length > self._max) |
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del(self, self._lruList[self._lru]) |
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} |
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function shiftLU (self, hit) { |
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delete self._lruList[ hit.lu ] |
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while (self._lru < self._mru && !self._lruList[self._lru]) self._lru ++ |
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} |
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function del (self, hit) { |
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if (hit) { |
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if (self._dispose) self._dispose(hit.key, hit.value) |
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self._length -= hit.length |
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self._itemCount -- |
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delete self._cache[ hit.key ] |
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shiftLU(self, hit) |
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} |
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} |
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// classy, since V8 prefers predictable objects. |
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function Entry (key, value, lu, length, now, maxAge) { |
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this.key = key |
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this.value = value |
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this.lu = lu |
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this.length = length |
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this.now = now |
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if (maxAge) this.maxAge = maxAge |
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} |
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})()
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