define([], function () {
  function order(c) {
    if (/^\d$/.test(c))
      return 0
    else if (/^[a-z]$/i.test(c))
      return c.charCodeAt(0)
    else if (c === "~")
      return -1
    else if (c)
      return c.charCodeAt(0) + 256
    else
      return 0
  }

  // Based on dpkg code
  function vercomp(a, b) {
    var apos = 0, bpos = 0
    while (apos < a.length || bpos < b.length) {
      var firstDiff = 0

      while ((apos < a.length && !/^\d$/.test(a[apos])) || (bpos < b.length && !/^\d$/.test(b[bpos]))) {
        var ac = order(a[apos])
        var bc = order(b[bpos])

        if (ac !== bc)
          return ac - bc

        apos++
        bpos++
      }

      while (a[apos] === "0")
        apos++

      while (b[bpos] === "0")
        bpos++

      while (/^\d$/.test(a[apos]) && /^\d$/.test(b[bpos])) {
        if (firstDiff === 0)
          firstDiff = a.charCodeAt(apos) - b.charCodeAt(bpos)

        apos++
        bpos++
      }

      if (/^\d$/.test(a[apos]))
        return 1

      if (/^\d$/.test(b[bpos]))
        return -1

      if (firstDiff !== 0)
        return firstDiff
    }

    return 0
  }

  return vercomp
})