compute method

@override CSSValue? compute([ DOMContext? domContext ])

Implementation

@override
CSSValue? compute([DOMContext? domContext]) {
  if (args.isEmpty) return null;

  var values = args.map((a) => CSSValue.from(a)).toList();
  var valuesNotNull = values.whereNotNull().toList();
  if (valuesNotNull.length != values.length) return null;

  var computed =
      valuesNotNull.map((a) => CSSFunction.computeValue(a)).toList();
  var computedNotNull = computed.whereNotNull().toList();
  if (computedNotNull.length != computed.length) return null;

  var computedCSSLength = computedNotNull.whereType<CSSLength>();

  if (computedCSSLength.length == computedNotNull.length) {
    var firstUnit = computedCSSLength.first.unit;

    if (computedCSSLength.every((a) => a.unit == firstUnit)) {
      var maxVal = computedCSSLength.map((a) => a.value).max;
      return CSSLength(maxVal, firstUnit);
    }
  }

  var computedCSSNumber = computedNotNull.whereType<CSSNumber>();

  if (computedCSSNumber.length == computedNotNull.length) {
    var maxVal = computedCSSLength.map((a) => a.value).max;
    return CSSNumber(maxVal);
  }

  return null;
}