BufferList.prototype.copy = function()

in digital-shadow/demo-car/js/aws-iot/aws-iot.js [921:979]

• 48 lines of code
• 21 McCabe index (conditional complexity)

BufferList.prototype.copy = function (dst, dstStart, srcStart, srcEnd) {
  if (typeof srcStart != 'number' || srcStart < 0)
    srcStart = 0
  if (typeof srcEnd != 'number' || srcEnd > this.length)
    srcEnd = this.length
  if (srcStart >= this.length)
    return dst || new Buffer(0)
  if (srcEnd <= 0)
    return dst || new Buffer(0)

  var copy   = !!dst
    , off    = this._offset(srcStart)
    , len    = srcEnd - srcStart
    , bytes  = len
    , bufoff = (copy && dstStart) || 0
    , start  = off[1]
    , l
    , i

  if (srcStart === 0 && srcEnd == this.length) {
    if (!copy) // slice, just return a full concat
      return Buffer.concat(this._bufs)

    for (i = 0; i < this._bufs.length; i++) {
      this._bufs[i].copy(dst, bufoff)
      bufoff += this._bufs[i].length
    }

    return dst
  }

  if (bytes <= this._bufs[off[0]].length - start) {
    return copy
      ? this._bufs[off[0]].copy(dst, dstStart, start, start + bytes)
      : this._bufs[off[0]].slice(start, start + bytes)
  }

  if (!copy) // a slice, we need something to copy in to
    dst = new Buffer(len)

  for (i = off[0]; i < this._bufs.length; i++) {
    l = this._bufs[i].length - start

    if (bytes > l) {
      this._bufs[i].copy(dst, bufoff, start)
    } else {
      this._bufs[i].copy(dst, bufoff, start, start + bytes)
      break
    }

    bufoff += l
    bytes -= l

    if (start)
      start = 0
  }

  return dst
}