Model-Driven Evolution of Software Architectures - Software and ...

5.5. GeneratingStateMachines 93
rule MergedSimpleState {
from s_in:UML!SimpleState (
thisModule.mergedStates->includes(s_in))
to s_out:UML!SimpleState(
nameiterate(s; mss:Set(UML!StateVertex)=Set{} |
if mss->exists(e|(e.mergeable(s)) then
mss
else
mss->including(s)
endif)
;
helper context UML!StateVertex def: mergeable(s:UML!StateVertex):
Boolean =
thisModule.unifiable(self.constraint,s.constraint) and self.name=s.
name
;
helper def: unifiable(cset1:Set(UML!Constraint),cset2:Set(UML!
Constraint)): Boolean =
let sharedSVs:Set(UML!Attribute) = cset1->collect(c|c.stateVariable
)->select(a|cset2->collect(c|c.stateVariable)->includes(a)) in
sharedSVs->forAll(a|cset1->select(c|c.stateVariable=a)=
cset2->select(c|c.stateVariable=a))
;
Listing 5.3:MergingSimpleStates
MergingFlatStateMachines Inthisstepwemergetheflatstatemachines.
Wemergeeverysetofstateswithunifiablestatevectorsandatleastone
identicalincomingtransition(intermsofeffectortrigger).
MergingofstatesisdonebytheruleandhelpersinListing5.3.Therule
matchesallstatesselectedbythe mergedStateshelperthatiterativelyselectsoneSimpleStatefromeverygroupofequalSimpleStatesinthesource
model. Acalltothe mergeablehelperresultsintruewhenthereceiving
StateVertexandtheparameterStateVertex1)(s)areunifiable,and2)have
thesamename(i.e.,theincomingtransitionshadthesametriggeroreffect).
The unifiablehelperevaluatestotruefortwosetsofConstraints
thatdonotspecifydifferentvaluesforthesamestatevariable,meaning
thattheconstraintthatreferstoaparticularstatevariablethatisalso
referredtointheotherset,isactuallyincludedinthatset.
Transitionsarematchedbyanotherrule(notshown).TodiscardredundantTransitions,itonlymatchesoneTransitionoftheTransitionsbetween
anytwosetsofSimpleStatesthataremerged.