node_modules/spdy-transport/lib/spdy-transport/utils.js

'use strict'

var util = require('util')
var isNode = require('detect-node')

// Node.js 0.8, 0.10 and 0.12 support
Object.assign = (process.versions.modules >= 46 || !isNode)
  ? Object.assign // eslint-disable-next-line
  : util._extend

function QueueItem () {
  this.prev = null
  this.next = null
}
exports.QueueItem = QueueItem

function Queue () {
  QueueItem.call(this)

  this.prev = this
  this.next = this
}
util.inherits(Queue, QueueItem)
exports.Queue = Queue

Queue.prototype.insertTail = function insertTail (item) {
  item.prev = this.prev
  item.next = this
  item.prev.next = item
  item.next.prev = item
}

Queue.prototype.remove = function remove (item) {
  var next = item.next
  var prev = item.prev

  item.next = item
  item.prev = item
  next.prev = prev
  prev.next = next
}

Queue.prototype.head = function head () {
  return this.next
}

Queue.prototype.tail = function tail () {
  return this.prev
}

Queue.prototype.isEmpty = function isEmpty () {
  return this.next === this
}

Queue.prototype.isRoot = function isRoot (item) {
  return this === item
}

function LockStream (stream) {
  this.locked = false
  this.queue = []
  this.stream = stream
}
exports.LockStream = LockStream

LockStream.prototype.write = function write (chunks, callback) {
  var self = this

  // Do not let it interleave
  if (this.locked) {
    this.queue.push(function () {
      return self.write(chunks, callback)
    })
    return
  }

  this.locked = true

  function done (err, chunks) {
    self.stream.removeListener('error', done)

    self.locked = false
    if (self.queue.length > 0) { self.queue.shift()() }
    callback(err, chunks)
  }

  this.stream.on('error', done)

  // Accumulate all output data
  var output = []
  function onData (chunk) {
    output.push(chunk)
  }
  this.stream.on('data', onData)

  function next (err) {
    self.stream.removeListener('data', onData)
    if (err) {
      return done(err)
    }

    done(null, output)
  }

  for (var i = 0; i < chunks.length - 1; i++) { this.stream.write(chunks[i]) }

  if (chunks.length > 0) {
    this.stream.write(chunks[i], next)
  } else { process.nextTick(next) }

  if (this.stream.execute) {
    this.stream.execute(function (err) {
      if (err) { return done(err) }
    })
  }
}

// Just finds the place in array to insert
function binaryLookup (list, item, compare) {
  var start = 0
  var end = list.length

  while (start < end) {
    var pos = (start + end) >> 1
    var cmp = compare(item, list[pos])

    if (cmp === 0) {
      start = pos
      end = pos
      break
    } else if (cmp < 0) {
      end = pos
    } else {
      start = pos + 1
    }
  }

  return start
}
exports.binaryLookup = binaryLookup

function binaryInsert (list, item, compare) {
  var index = binaryLookup(list, item, compare)

  list.splice(index, 0, item)
}
exports.binaryInsert = binaryInsert

function binarySearch (list, item, compare) {
  var index = binaryLookup(list, item, compare)

  if (index >= list.length) {
    return -1
  }

  if (compare(item, list[index]) === 0) {
    return index
  }

  return -1
}
exports.binarySearch = binarySearch

function Timeout (object) {
  this.delay = 0
  this.timer = null
  this.object = object
}
exports.Timeout = Timeout

Timeout.prototype.set = function set (delay, callback) {
  this.delay = delay
  this.reset()
  if (!callback) { return }

  if (this.delay === 0) {
    this.object.removeListener('timeout', callback)
  } else {
    this.object.once('timeout', callback)
  }
}

Timeout.prototype.reset = function reset () {
  if (this.timer !== null) {
    clearTimeout(this.timer)
    this.timer = null
  }

  if (this.delay === 0) { return }

  var self = this
  this.timer = setTimeout(function () {
    self.timer = null
    self.object.emit('timeout')
  }, this.delay)
}