Function Buffer

MathBox/mathbox-core.js:981–1039

* Class: Buffer * ============= * * The Buffer constructor returns instances of `Uint8Array` that are augmented * with function properties for all the node `Buffer` API functions. We use * `Uint8Array` so that square bracket notation works as expected -- it returns * a single octet. * * By a

(subject, encoding, noZero)

 * prototype.
 */
function Buffer (subject, encoding, noZero) {
  if (!(this instanceof Buffer))
    return new Buffer(subject, encoding, noZero)

  var type = typeof subject

  // Workaround: node's base64 implementation allows for non-padded strings
  // while base64-js does not.
  if (encoding === 'base64' && type === 'string') {
    subject = stringtrim(subject)
    while (subject.length % 4 !== 0) {
      subject = subject + '='
    }
  }

  // Find the length
  var length
  if (type === 'number')
    length = coerce(subject)
  else if (type === 'string')
    length = Buffer.byteLength(subject, encoding)
  else if (type === 'object')
    length = coerce(subject.length) // assume that object is array-like
  else
    throw new Error('First argument needs to be a number, array or string.')

  var buf
  if (Buffer._useTypedArrays) {
    // Preferred: Return an augmented `Uint8Array` instance for best performance
    buf = Buffer._augment(new Uint8Array(length))
  } else {
    // Fallback: Return THIS instance of Buffer (created by `new`)
    buf = this
    buf.length = length
    buf._isBuffer = true
  }

  var i
  if (Buffer._useTypedArrays && typeof subject.byteLength === 'number') {
    // Speed optimization -- use set if we're copying from a typed array
    buf._set(subject)
  } else if (isArrayish(subject)) {
    // Treat array-ish objects as a byte array
    for (i = 0; i < length; i++) {
      if (Buffer.isBuffer(subject))
        buf[i] = subject.readUInt8(i)
      else
        buf[i] = subject[i]
    }
  } else if (type === 'string') {
    buf.write(subject, 0, encoding)
  } else if (type === 'number' && !Buffer._useTypedArrays && !noZero) {
    for (i = 0; i < length; i++) {
      buf[i] = 0
    }
  }

  return buf