--- /dev/null
+# lru cache
+
+A cache object that deletes the least-recently-used items.
+
+[](https://travis-ci.org/isaacs/node-lru-cache) [](https://coveralls.io/github/isaacs/node-lru-cache)
+
+## Installation:
+
+```javascript
+npm install lru-cache --save
+```
+
+## Usage:
+
+```javascript
+var LRU = require("lru-cache")
+ , options = { max: 500
+ , length: function (n, key) { return n * 2 + key.length }
+ , dispose: function (key, n) { n.close() }
+ , maxAge: 1000 * 60 * 60 }
+ , cache = LRU(options)
+ , otherCache = LRU(50) // sets just the max size
+
+cache.set("key", "value")
+cache.get("key") // "value"
+
+// non-string keys ARE fully supported
+// but note that it must be THE SAME object, not
+// just a JSON-equivalent object.
+var someObject = { a: 1 }
+cache.set(someObject, 'a value')
+// Object keys are not toString()-ed
+cache.set('[object Object]', 'a different value')
+assert.equal(cache.get(someObject), 'a value')
+// A similar object with same keys/values won't work,
+// because it's a different object identity
+assert.equal(cache.get({ a: 1 }), undefined)
+
+cache.reset() // empty the cache
+```
+
+If you put more stuff in it, then items will fall out.
+
+If you try to put an oversized thing in it, then it'll fall out right
+away.
+
+## Options
+
+* `max` The maximum size of the cache, checked by applying the length
+ function to all values in the cache. Not setting this is kind of
+ silly, since that's the whole purpose of this lib, but it defaults
+ to `Infinity`.
+* `maxAge` Maximum age in ms. Items are not pro-actively pruned out
+ as they age, but if you try to get an item that is too old, it'll
+ drop it and return undefined instead of giving it to you.
+* `length` Function that is used to calculate the length of stored
+ items. If you're storing strings or buffers, then you probably want
+ to do something like `function(n, key){return n.length}`. The default is
+ `function(){return 1}`, which is fine if you want to store `max`
+ like-sized things. The item is passed as the first argument, and
+ the key is passed as the second argumnet.
+* `dispose` Function that is called on items when they are dropped
+ from the cache. This can be handy if you want to close file
+ descriptors or do other cleanup tasks when items are no longer
+ accessible. Called with `key, value`. It's called *before*
+ actually removing the item from the internal cache, so if you want
+ to immediately put it back in, you'll have to do that in a
+ `nextTick` or `setTimeout` callback or it won't do anything.
+* `stale` By default, if you set a `maxAge`, it'll only actually pull
+ stale items out of the cache when you `get(key)`. (That is, it's
+ not pre-emptively doing a `setTimeout` or anything.) If you set
+ `stale:true`, it'll return the stale value before deleting it. If
+ you don't set this, then it'll return `undefined` when you try to
+ get a stale entry, as if it had already been deleted.
+* `noDisposeOnSet` By default, if you set a `dispose()` method, then
+ it'll be called whenever a `set()` operation overwrites an existing
+ key. If you set this option, `dispose()` will only be called when a
+ key falls out of the cache, not when it is overwritten.
+
+## API
+
+* `set(key, value, maxAge)`
+* `get(key) => value`
+
+ Both of these will update the "recently used"-ness of the key.
+ They do what you think. `maxAge` is optional and overrides the
+ cache `maxAge` option if provided.
+
+ If the key is not found, `get()` will return `undefined`.
+
+ The key and val can be any value.
+
+* `peek(key)`
+
+ Returns the key value (or `undefined` if not found) without
+ updating the "recently used"-ness of the key.
+
+ (If you find yourself using this a lot, you *might* be using the
+ wrong sort of data structure, but there are some use cases where
+ it's handy.)
+
+* `del(key)`
+
+ Deletes a key out of the cache.
+
+* `reset()`
+
+ Clear the cache entirely, throwing away all values.
+
+* `has(key)`
+
+ Check if a key is in the cache, without updating the recent-ness
+ or deleting it for being stale.
+
+* `forEach(function(value,key,cache), [thisp])`
+
+ Just like `Array.prototype.forEach`. Iterates over all the keys
+ in the cache, in order of recent-ness. (Ie, more recently used
+ items are iterated over first.)
+
+* `rforEach(function(value,key,cache), [thisp])`
+
+ The same as `cache.forEach(...)` but items are iterated over in
+ reverse order. (ie, less recently used items are iterated over
+ first.)
+
+* `keys()`
+
+ Return an array of the keys in the cache.
+
+* `values()`
+
+ Return an array of the values in the cache.
+
+* `length`
+
+ Return total length of objects in cache taking into account
+ `length` options function.
+
+* `itemCount`
+
+ Return total quantity of objects currently in cache. Note, that
+ `stale` (see options) items are returned as part of this item
+ count.
+
+* `dump()`
+
+ Return an array of the cache entries ready for serialization and usage
+ with 'destinationCache.load(arr)`.
+
+* `load(cacheEntriesArray)`
+
+ Loads another cache entries array, obtained with `sourceCache.dump()`,
+ into the cache. The destination cache is reset before loading new entries
+
+* `prune()`
+
+ Manually iterates over the entire cache proactively pruning old entries
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