add method

@override void add(String name, Object value, { bool preserveHeaderCase = false, })

Adds a header value.

The header named name will have a string value derived from value added to its list of values.

Some headers are single valued, and for these, adding a value will replace a previous value. If the value is a DateTime, an HTTP date format will be applied. If the value is an Iterable, each element will be added separately. For all other types the default Object.toString method will be used.

Header names are converted to lower-case unless preserveHeaderCase is set to true. If two header names are the same when converted to lower-case, they are considered to be the same header, with one set of values.

The current case of the a header name is that of the name used by the last set or add call for that header.

Implementation

@override
void add(String name, Object value, {bool preserveHeaderCase = false}) {
  // Dart 2.8 adds the preserveHeaderCase option
  final lcName = name.toLowerCase();

  var values = _data[lcName];
  if (values == null) {
    final createdList = <String>[];
    _data[lcName] = createdList;
    values = createdList;
  }

  // A HttpHeader from a real HTTP request discards any whitespace from
  // the left (i.e. after the colon), but preserves any whitespaces at the
  // right end of the line. Empty string values are preserved.
  // Values which are empty strings, and values which are all whitespace,
  // are kept as an empty string.
  //
  // Note: when testing, be aware clients may modify/discard headers
  // before sending them.

  values.add(value.toString().trimLeft());

  _originalHeaderNames[lcName] = preserveHeaderCase ? name : lcName;
}