test-buddy/lib/utils.js

/// Module utils
//
// Common utilities.
//
// (Most of this code should be moved to their own modules given some
// time, they're just here because it's easy to just put everything here
// and get a working prototype, then refactor.)
//
// Copyright (c) 2013 Quildreen Motta
//
// Permission is hereby granted, free of charge, to any person
// obtaining a copy of this software and associated documentation files
// (the "Software"), to deal in the Software without restriction,
// including without limitation the rights to use, copy, modify, merge,
// publish, distribute, sublicense, and/or sell copies of the Software,
// and to permit persons to whom the Software is furnished to do so,
// subject to the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

//// -- Dependencies ---------------------------------------------------
var pinky = require('pinky')


//// -- Collections ----------------------------------------------------

///// λ flatten
//
// Flattens a list of lists recursively.
//
// :: [[a]] -> [a]
function flatten(xs) {
  return xs.reduce(function(r, x) {
             Array.isArray(x)?  r.push.apply(r, flatten(x))
           : /* otherwise */    r.push(x)
           return r
         }, [])
}


//// -- Asynchronous stuff ---------------------------------------------

///// λ timeout
//
// Creates a promise that is rejected if not fulfilled within a given
// timeframe.
//
// :: Number, Promise a -> Promise a
//
function timeout(ms, promise) {
  var err = new Error('Timeout of ' + ms + ' exceeded.')
  var p   = pinky(promise)

  var timer = setTimeout(p.reject.bind(null, err), ms)
  p.always(function(){ clearTimeout(timer) })
  return p
}

///// λ sequentially
//
// Runs a series of promise-returning functions sequentially.
//
// :: [a... -> Promise b] -> Promise [b]
function sequentially(fns) {
  if (fns.length == 0)  return pinky([])

  var result  = []
  var promise = pinky()

  next()

  return promise

  function next() {
    var f = fns.shift()
    f().always(function(value) {
                 result.push(value)
                 if (!fns.length)  promise.fulfill(result)
                 else              next()
               })
  }
}


//// -- Exports --------------------------------------------------------
module.exports = { flatten      : flatten
                 , sequentially : sequentially
                 , timeout      : timeout }