text: /* @flow */
  
  import { toArray } from '../util/index'
  
  /**
   * 插件扩展，比如 vue-router
   */
  export function initUse (Vue: GlobalAPI) {
    Vue.use = function (plugin: Function | Object) {
      const installedPlugins = (this._installedPlugins || (this._installedPlugins = []))
      if (installedPlugins.indexOf(plugin) > -1) {
        return this
      }
  
      // additional parameters
      const args = toArray(arguments, 1)
      args.unshift(this)
      if (typeof plugin.install === 'function') {
        plugin.install.apply(plugin, args)
      } else if (typeof plugin === 'function') {
        plugin.apply(null, args)
      }
      installedPlugins.push(plugin)
      return this
    }
  }
  