refactor(language): clarify containment hierarchy

3 files changed, 74 insertions, 9 deletions

diff --git a/subprojects/language/src/main/java/tools/refinery/language/Problem.xtext b/subprojects/language/src/main/java/tools/refinery/language/Problem.xtext
index f7b86dca..2a5af628 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/Problem.xtext
+++ b/subprojects/language/src/main/java/tools/refinery/language/Problem.xtext
@@ -26,15 +26,23 @@ EnumDeclaration:
 EnumLiteral returns Node:
         name=Identifier;
 
+enum ReferenceKind:
+        REFERENCE="refers" | CONTAINMENT="contains" | CONTAINER="container";
+
 ReferenceDeclaration:
-        (containment?="contains" | "refers")?
-        referenceType=[Relation|QualifiedName]
+        (
+                kind=ReferenceKind referenceType=[Relation|QualifiedName] |
+                referenceType=[Relation|NonRelationKindQualifiedName]
+        )
         ("[" multiplicity=Multiplicity "]")?
         name=Identifier
         ("opposite" opposite=[ReferenceDeclaration|QualifiedName])?;
 
+enum PredicateKind:
+        ERROR="error" | CONTAINED="contained" | CONTAINMENT="containment";
+
 PredicateDefinition:
-        (error?="error" "pred"? | "pred")
+        (kind=PredicateKind "pred"? | "pred")
         name=Identifier
         "(" (parameters+=Parameter ("," parameters+=Parameter)*)? ")"
         ("<->" bodies+=Conjunction (";" bodies+=Conjunction)*)?
@@ -150,7 +158,7 @@ ScopeDeclaration:
         "scope" typeScopes+=TypeScope ("," typeScopes+=TypeScope)* ".";
 
 TypeScope:
-        targetType=[ClassDeclaration|QualifiedName]
+        targetType=[Relation|QualifiedName]
         (increment?="+=" | "=")
         multiplicity=DefiniteMultiplicity;
 
@@ -175,12 +183,19 @@ IndividualDeclaration:
 UpperBound returns ecore::EInt:
         INT | "*";
 
+NonRelationKindQualifiedName hidden():
+        NonRelationKindIdentifier ("::" Identifier)*;
+
 QualifiedName hidden():
         Identifier ("::" Identifier)*;
 
+NonRelationKindIdentifier:
+        ID | "true" | "false" | "unknown" | "error" | "class" | "abstract" | "extends" | "enum" |
+        "pred" | "indiv" | "problem" | "new" | "delete" | "rule" | "may" | "must" | "current" |
+        "count" | "default" | "scope" | "contained" | "containment";
+
 Identifier:
-        ID | "true" | "false" | "unknown" | "error" | "class" | "abstract" | "extends" | "enum" | "pred" |
-        "indiv" | "problem" | "new" | "delete" | "rule" | "may" | "must" | "current" | "count";
+        NonRelationKindIdentifier | "refers" | "contains" | "container";
 
 Integer returns ecore::EInt hidden():
         "-"? INT;
diff --git a/subprojects/language/src/main/java/tools/refinery/language/ProblemUtil.java b/subprojects/language/src/main/java/tools/refinery/language/ProblemUtil.java
index b1e39176..0be296fd 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/ProblemUtil.java
+++ b/subprojects/language/src/main/java/tools/refinery/language/ProblemUtil.java
@@ -27,6 +27,10 @@ public final class ProblemUtil {
 
         public static final String NODE_CLASS_NAME = "node";
 
+        public static final String DOMAIN_CLASS_NAME = "domain";
+
+        public static final String DATA_CLASS_NAME = "data";
+
         private ProblemUtil() {
                 throw new IllegalStateException("This is a static utility class and should not be instantiated directly");
         }
@@ -80,15 +84,15 @@ public final class ProblemUtil {
                 return false;
         }
 
-        public static Optional<ClassDeclaration> getNodeClassDeclaration(EObject context) {
+        public static Optional<ClassDeclaration> getBuiltinClassDeclaration(EObject context, String name) {
                 return getBuiltInLibrary(context).flatMap(problem -> problem.getStatements().stream()
                                 .filter(ClassDeclaration.class::isInstance).map(ClassDeclaration.class::cast)
-                                .filter(declaration -> NODE_CLASS_NAME.equals(declaration.getName())).findFirst());
+                                .filter(declaration -> name.equals(declaration.getName())).findFirst());
         }
 
         public static Collection<ClassDeclaration> getSuperclassesAndSelf(ClassDeclaration classDeclaration) {
                 Set<ClassDeclaration> found = new HashSet<>();
-                getNodeClassDeclaration(classDeclaration).ifPresent(found::add);
+                getBuiltinClassDeclaration(classDeclaration, NODE_CLASS_NAME).ifPresent(found::add);
                 Deque<ClassDeclaration> queue = new ArrayDeque<>();
                 queue.addLast(classDeclaration);
                 while (!queue.isEmpty()) {
@@ -102,6 +106,11 @@ public final class ProblemUtil {
                                 }
                         }
                 }
+                getBuiltinClassDeclaration(classDeclaration, DATA_CLASS_NAME).ifPresent((dataClassDelcaration) -> {
+                        if (!found.contains(dataClassDelcaration)) {
+                                getBuiltinClassDeclaration(classDeclaration, DOMAIN_CLASS_NAME).ifPresent(found::add);
+                        }
+                });
                 return found;
         }
 
@@ -113,6 +122,28 @@ public final class ProblemUtil {
                 return referenceDeclarations;
         }
 
+        public static boolean isDataClass(Relation relation) {
+                if (relation instanceof ClassDeclaration classDeclaration) {
+                        var supertypes = getSuperclassesAndSelf(classDeclaration);
+                        return getBuiltinClassDeclaration(classDeclaration, DATA_CLASS_NAME).map(supertypes::contains)
+                                        .orElse(false);
+                }
+                return false;
+        }
+
+        public static boolean isContainmentReference(ReferenceDeclaration referenceDeclaration) {
+                switch (referenceDeclaration.getKind()) {
+                case REFERENCE, CONTAINER:
+                        return false;
+                case CONTAINMENT:
+                        return true;
+                case DEFAULT:
+                        return isDataClass(referenceDeclaration.getReferenceType());
+                default:
+                        throw new IllegalArgumentException("Unknown reference kind " + referenceDeclaration.getKind());
+                }
+        }
+
         private static URI getLibraryUri(String libraryName) {
                 return URI.createURI(ProblemUtil.class.getClassLoader()
                                 .getResource("tools/refinery/language/%s.problem".formatted(libraryName)).toString());
diff --git a/subprojects/language/src/main/resources/tools/refinery/language/builtin.problem b/subprojects/language/src/main/resources/tools/refinery/language/builtin.problem
index 323e03f1..e39ff1a3 100644
--- a/subprojects/language/src/main/resources/tools/refinery/language/builtin.problem
+++ b/subprojects/language/src/main/resources/tools/refinery/language/builtin.problem
@@ -19,3 +19,22 @@ class real extends data.
 class int extends data.
 
 class string extends data.
+
+pred contained(node node).
+
+pred contains(node container, node contained).
+
+pred root(node node).
+
+% error missingContainer(contained node) <->
+%     !contains(node, _), !root(node).
+%
+% error tooManyContainers(contained node) <->
+%     count contains(_, node) > 1
+% ;
+%     contains(_, node), root(node)
+% ;
+%         contains(_, node), !contained(node).
+%
+% error containmentCycle(node node) <->
+%     contains+(node, node).