From the diagram on page 570 of the UML spec I concluded that a Lifeline should have the events property, holding an OrderedSet(OcurrenceSpecification). Unfortunately it is not there, at least in the QVTo implementation that I use.
All I have is the coveredBy property, serving me with an (unordered) Set(InteractionFragment). Since my transformation relies on the correct order of MessageOcurrenceSpecification I somehow need to implement myself what I expected to be implemented by the missing events property.
This is what I have so far:
helper Lifeline::getEvents (): OrderedSet(OccurrenceSpecification) {
return self.coveredBy->selectByKind(OccurrenceSpecification)->sortedBy(true);
}
Obviously sortedBy(true) does not get me far, but I don't know any further. Who can help?
All I could find so far were other people struggling with the same issue years ago, but no solution:
Based on the answer by Vincent combined with input from a colleague of mine I came up with the following solution for QVTo:
-- -----------------------------------------------------------------------------
-- Polyfill for the missing Lifeline::events property
query Lifeline::getEvents (): OrderedSet(OccurrenceSpecification) {
return self.interaction.fragment
->selectByKind(OccurrenceSpecification)
->select(os: OccurrenceSpecification | os.covered->includes(self))
->asOrderedSet();
}