refactor: enable data variable unification

This is needed for demand set transformation of DNFs with input data parameters,
where the result of the transformation has an out data parameter that has to be
unified with the variable in the parent clause.

2 files changed, 37 insertions, 1 deletions

diff --git a/subprojects/store-query-viatra/src/main/java/tools/refinery/store/query/viatra/internal/pquery/Dnf2PQuery.java b/subprojects/store-query-viatra/src/main/java/tools/refinery/store/query/viatra/internal/pquery/Dnf2PQuery.java
index 38fd017e..d51bc9fc 100644
--- a/subprojects/store-query-viatra/src/main/java/tools/refinery/store/query/viatra/internal/pquery/Dnf2PQuery.java
+++ b/subprojects/store-query-viatra/src/main/java/tools/refinery/store/query/viatra/internal/pquery/Dnf2PQuery.java
@@ -88,7 +88,7 @@ public class Dnf2PQuery {
                 List<PParameter> parameterList = new ArrayList<>();
                 for (var parameter : dnfQuery.getSymbolicParameters()) {
                         var direction = switch (parameter.getDirection()) {
-                                case OUT -> parameter.isUnifiable() ? PParameterDirection.INOUT : PParameterDirection.OUT;
+                                case OUT -> PParameterDirection.INOUT;
                                 case IN -> throw new IllegalArgumentException("Query %s with input parameter %s is not supported"
                                                 .formatted(dnfQuery, parameter.getVariable()));
                         };
diff --git a/subprojects/store-query-viatra/src/test/java/tools/refinery/store/query/viatra/FunctionalQueryTest.java b/subprojects/store-query-viatra/src/test/java/tools/refinery/store/query/viatra/FunctionalQueryTest.java
index c4f877c5..7f5c24fe 100644
--- a/subprojects/store-query-viatra/src/test/java/tools/refinery/store/query/viatra/FunctionalQueryTest.java
+++ b/subprojects/store-query-viatra/src/test/java/tools/refinery/store/query/viatra/FunctionalQueryTest.java
@@ -424,6 +424,42 @@ class FunctionalQueryTest {
         }
 
         @QueryEngineTest
+        void multipleAssignmentTest(QueryEvaluationHint hint) {
+                var query = Query.of("MultipleAssignment", Integer.class, (builder, p1, p2, output) -> builder
+                                .clause(Integer.class, Integer.class, (x1, x2) -> List.of(
+                                                ageView.call(p1, x1),
+                                                ageView.call(p2, x2),
+                                                output.assign(mul(x1, constant(2))),
+                                                output.assign(mul(x2, constant(3)))
+                                )));
+
+                var store = ModelStore.builder()
+                                .symbols(age)
+                                .with(ViatraModelQueryAdapter.builder()
+                                                .defaultHint(hint)
+                                                .queries(query))
+                                .build();
+
+                var model = store.createEmptyModel();
+                var ageInterpretation = model.getInterpretation(age);
+                var queryEngine = model.getAdapter(ModelQueryAdapter.class);
+                var queryResultSet = queryEngine.getResultSet(query);
+
+                ageInterpretation.put(Tuple.of(0), 3);
+                ageInterpretation.put(Tuple.of(1), 2);
+                ageInterpretation.put(Tuple.of(2), 15);
+                ageInterpretation.put(Tuple.of(3), 10);
+
+                queryEngine.flushChanges();
+                assertNullableResults(Map.of(
+                                Tuple.of(0, 1), Optional.of(6),
+                                Tuple.of(1, 0), Optional.empty(),
+                                Tuple.of(2, 3), Optional.of(30),
+                                Tuple.of(3, 2), Optional.empty()
+                ), queryResultSet);
+        }
+
+        @QueryEngineTest
         void notFunctionalTest(QueryEvaluationHint hint) {
                 var query = Query.of("NotFunctional", Integer.class, (builder, p1, output) -> builder.clause((p2) -> List.of(
                                 personView.call(p1),