merge method

Implementation

bool merge(CSSStyleDeclaration other) {
  final List<String> properties = _effectivePropertyNamesSnapshot();
  bool updateStatus = false;

  // Apply updates + additions based on `other`.
  for (final MapEntry<String, CSSPropertyValue> entry in other) {
    final String propertyName = entry.key;
    final CSSPropertyValue otherValue = entry.value;
    final CSSPropertyValue? prevValue = _getEffectivePropertyValueEntry(propertyName);

    // Mirror previous behavior: if the property does not exist on `this`,
    // stage the incoming value directly (even when empty).
    if (prevValue == null) {
      _setStagedPropertyValue(propertyName, otherValue);
      updateStatus = true;
      continue;
    }

    if (isNullOrEmptyValue(prevValue) && isNullOrEmptyValue(otherValue)) {
      continue;
    } else if (!isNullOrEmptyValue(prevValue) && isNullOrEmptyValue(otherValue)) {
      // Remove property.
      removeProperty(propertyName, prevValue.important ? true : null);
      updateStatus = true;
    } else if (!_samePropertyValue(prevValue, otherValue)) {
      _setStagedPropertyValue(propertyName, otherValue);
      updateStatus = true;
    }
  }

  // Remove properties missing in `other`.
  for (final String propertyName in properties) {
    final CSSPropertyValue? prevValue = _getEffectivePropertyValueEntry(propertyName);
    if (isNullOrEmptyValue(prevValue)) continue;
    if (other._getEffectivePropertyValueEntry(propertyName) != null) continue;

    removeProperty(propertyName, prevValue?.important == true ? true : null);
    updateStatus = true;
  }

  return updateStatus;
}