choo/component/cache.js

A 4kb framework for creating sturdy frontend applications

var assert = require('assert')
var LRU = require('nanolru')

module.exports = ChooComponentCache

function ChooComponentCache (state, emit, lru) {
  assert.ok(this instanceof ChooComponentCache, 'ChooComponentCache should be created with `new`')

  assert.equal(typeof state, 'object', 'ChooComponentCache: state should be type object')
  assert.equal(typeof emit, 'function', 'ChooComponentCache: emit should be type function')

  if (typeof lru === 'number') this.cache = new LRU(lru)
  else this.cache = lru || new LRU(100)
  this.state = state
  this.emit = emit
}

// Get & create component instances.
ChooComponentCache.prototype.render = function (Component, id) {
  assert.equal(typeof Component, 'function', 'ChooComponentCache.render: Component should be type function')
  assert.ok(typeof id === 'string' || typeof id === 'number', 'ChooComponentCache.render: id should be type string or type number')

  var el = this.cache.get(id)
  if (!el) {
    var args = []
    for (var i = 2, len = arguments.length; i < len; i++) {
      args.push(arguments[i])
    }
    args.unshift(Component, id, this.state, this.emit)
    el = newCall.apply(newCall, args)
    this.cache.set(id, el)
  }

  return el
}

// Because you can't call `new` and `.apply()` at the same time. This is a mad
// hack, but hey it works so we gonna go for it. Whoop.
function newCall (Cls) {
  return new (Cls.bind.apply(Cls, arguments)) // eslint-disable-line
}