function extractProtocol(address, location) {
  address = trimLeft(address);
  address = address.replace(CRHTLF, '');
  location = location || {};

  var match = protocolre.exec(address);
  var protocol = match[1] ? match[1].toLowerCase() : '';
  var forwardSlashes = !!match[2];
  var otherSlashes = !!match[3];
  var slashesCount = 0;
  var rest;

  if (forwardSlashes) {
    if (otherSlashes) {
      rest = match[2] + match[3] + match[4];
      slashesCount = match[2].length + match[3].length;
    } else {
      rest = match[2] + match[4];
      slashesCount = match[2].length;
    }
  } else {
    if (otherSlashes) {
      rest = match[3] + match[4];
      slashesCount = match[3].length;
    } else {
      rest = match[4]
    }
  }

  if (protocol === 'file:') {
    if (slashesCount >= 2) {
      rest = rest.slice(2);
    }
  } else if (isSpecial(protocol)) {
    rest = match[4];
  } else if (protocol) {
    if (forwardSlashes) {
      rest = rest.slice(2);
    }
  } else if (slashesCount >= 2 && isSpecial(location.protocol)) {
    rest = match[4];
  }

  return {
    protocol: protocol,
    slashes: forwardSlashes || isSpecial(protocol),
    slashesCount: slashesCount,
    rest: rest
  };
}
Extract protocol information from a URL with/without double slash ("//").

@param {String} address URL we want to extract from.
@param {Object} location
@return {ProtocolExtract} Extracted information.
@private