Dirt simple LRU cache

simplelrucache.coffee

module.exports = (options = {})->
  cache = {}
  cacheSize = 0
  maxKeys = options.maxKeys || 50
  seq = 1

  get: (key)->
    if c = cache[key]
      c.used = seq++
      return c.value

  set: (key, value)->
    @freeLRU() if cacheSize >= maxKeys && !cache[key]
    cache[key] =
      used: seq++
      value: value
    cacheSize = Object.keys(cache).length
    return cacheSize

  freeLRU: ->
    oldestKey = null
    oldest = null
    for key, c of cache
      if !oldestKey || c.used < oldest
        oldestKey = key
        oldest = c.used
    delete cache[oldestKey] if oldestKey
    return oldestKey