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;(function () { // closure for web browsers
if (typeof module === 'object' && module.exports) {
module.exports = LRUCache
} else {
// just set the global for non-node platforms.
this.LRUCache = LRUCache
}
function hOP (obj, key) {
return Object.prototype.hasOwnProperty.call(obj, key)
}
function naiveLength () { return 1 }
function LRUCache (options) {
if (!(this instanceof LRUCache))
return new LRUCache(options)
if (typeof options === 'number')
options = { max: options }
if (!options)
options = {}
this._max = options.max
// Kind of weird to have a default max of Infinity, but oh well.
if (!this._max || !(typeof this._max === "number") || this._max <= 0 )
this._max = Infinity
this._lengthCalculator = options.length || naiveLength
if (typeof this._lengthCalculator !== "function")
this._lengthCalculator = naiveLength
this._allowStale = options.stale || false
this._maxAge = options.maxAge || null
this._dispose = options.dispose
this.reset()
}
// resize the cache when the max changes.
Object.defineProperty(LRUCache.prototype, "max",
{ set : function (mL) {
if (!mL || !(typeof mL === "number") || mL <= 0 ) mL = Infinity
this._max = mL
if (this._length > this._max) trim(this)
}
, get : function () { return this._max }
, enumerable : true
})
// resize the cache when the lengthCalculator changes.
Object.defineProperty(LRUCache.prototype, "lengthCalculator",
{ set : function (lC) {
if (typeof lC !== "function") {
this._lengthCalculator = naiveLength
this._length = this._itemCount
for (var key in this._cache) {
this._cache[key].length = 1
}
} else {
this._lengthCalculator = lC
this._length = 0
for (var key in this._cache) {
this._cache[key].length = this._lengthCalculator(this._cache[key].value)
this._length += this._cache[key].length
}
}
if (this._length > this._max) trim(this)
}
, get : function () { return this._lengthCalculator }
, enumerable : true
})
Object.defineProperty(LRUCache.prototype, "length",
{ get : function () { return this._length }
, enumerable : true
})
Object.defineProperty(LRUCache.prototype, "itemCount",
{ get : function () { return this._itemCount }
, enumerable : true
})
LRUCache.prototype.forEach = function (fn, thisp) {
thisp = thisp || this
var i = 0;
for (var k = this._mru - 1; k >= 0 && i < this._itemCount; k--) if (this._lruList[k]) {
i++
var hit = this._lruList[k]
if (this._maxAge && (Date.now() - hit.now > this._maxAge)) {
del(this, hit)
if (!this._allowStale) hit = undefined
}
if (hit) {
fn.call(thisp, hit.value, hit.key, this)
}
}
}
LRUCache.prototype.keys = function () {
var keys = new Array(this._itemCount)
var i = 0
for (var k = this._mru - 1; k >= 0 && i < this._itemCount; k--) if (this._lruList[k]) {
var hit = this._lruList[k]
keys[i++] = hit.key
}
return keys
}
LRUCache.prototype.values = function () {
var values = new Array(this._itemCount)
var i = 0
for (var k = this._mru - 1; k >= 0 && i < this._itemCount; k--) if (this._lruList[k]) {
var hit = this._lruList[k]
values[i++] = hit.value
}
return values
}
LRUCache.prototype.reset = function () {
if (this._dispose && this._cache) {
for (var k in this._cache) {
this._dispose(k, this._cache[k].value)
}
}
this._cache = Object.create(null) // hash of items by key
this._lruList = Object.create(null) // list of items in order of use recency
this._mru = 0 // most recently used
this._lru = 0 // least recently used
this._length = 0 // number of items in the list
this._itemCount = 0
}
// Provided for debugging/dev purposes only. No promises whatsoever that
// this API stays stable.
LRUCache.prototype.dump = function () {
return this._cache
}
LRUCache.prototype.dumpLru = function () {
return this._lruList
}
LRUCache.prototype.set = function (key, value) {
if (hOP(this._cache, key)) {
// dispose of the old one before overwriting
if (this._dispose) this._dispose(key, this._cache[key].value)
if (this._maxAge) this._cache[key].now = Date.now()
this._cache[key].value = value
this.get(key)
return true
}
var len = this._lengthCalculator(value)
var age = this._maxAge ? Date.now() : 0
var hit = new Entry(key, value, this._mru++, len, age)
// oversized objects fall out of cache automatically.
if (hit.length > this._max) {
if (this._dispose) this._dispose(key, value)
return false
}
this._length += hit.length
this._lruList[hit.lu] = this._cache[key] = hit
this._itemCount ++
if (this._length > this._max) trim(this)
return true
}
LRUCache.prototype.has = function (key) {
if (!hOP(this._cache, key)) return false
var hit = this._cache[key]
if (this._maxAge && (Date.now() - hit.now > this._maxAge)) {
return false
}
return true
}
LRUCache.prototype.get = function (key) {
return get(this, key, true)
}
LRUCache.prototype.peek = function (key) {
return get(this, key, false)
}
LRUCache.prototype.pop = function () {
var hit = this._lruList[this._lru]
del(this, hit)
return hit || null
}
LRUCache.prototype.del = function (key) {
del(this, this._cache[key])
}
function get (self, key, doUse) {
var hit = self._cache[key]
if (hit) {
if (self._maxAge && (Date.now() - hit.now > self._maxAge)) {
del(self, hit)
if (!self._allowStale) hit = undefined
} else {
if (doUse) use(self, hit)
}
if (hit) hit = hit.value
}
return hit
}
function use (self, hit) {
shiftLU(self, hit)
hit.lu = self._mru ++
self._lruList[hit.lu] = hit
}
function trim (self) {
while (self._lru < self._mru && self._length > self._max)
del(self, self._lruList[self._lru])
}
function shiftLU (self, hit) {
delete self._lruList[ hit.lu ]
while (self._lru < self._mru && !self._lruList[self._lru]) self._lru ++
}
function del (self, hit) {
if (hit) {
if (self._dispose) self._dispose(hit.key, hit.value)
self._length -= hit.length
self._itemCount --
delete self._cache[ hit.key ]
shiftLU(self, hit)
}
}
// classy, since V8 prefers predictable objects.
function Entry (key, value, lu, length, now) {
this.key = key
this.value = value
this.lu = lu
this.length = length
this.now = now
}
})()