Adapt LP conversion to RSA check

Part of the process involves the search of unsafe roles in the input
ontology. This is still to be implemented and for now the set of unsafe
roles for the testing example is hardcoded.

1 files changed, 30 insertions, 16 deletions

diff --git a/src/main/scala/rsacomb/RDFoxClassExprConverter.scala b/src/main/scala/rsacomb/RDFoxClassExprConverter.scala
index 58bee44..227c25b 100644
--- a/src/main/scala/rsacomb/RDFoxClassExprConverter.scala
+++ b/src/main/scala/rsacomb/RDFoxClassExprConverter.scala
@@ -10,14 +10,17 @@ import tech.oxfordsemantic.jrdfox.logic.{Atom, Term, Variable, Literal, Datatype
 
 import rsacomb.SkolemStrategy
 import rsacomb.RDFoxRuleShards
+import org.semanticweb.owlapi.model.OWLObjectPropertyExpression
+import org.semanticweb.owlapi.model.OWLObjectProperty
 
 object RDFoxClassExprConverter {
 
-  def apply(term : Term, skolem : SkolemStrategy) : RDFoxClassExprConverter =
-        new RDFoxClassExprConverter(term, skolem)
-
-  def apply(term : Term) : RDFoxClassExprConverter =
-        new RDFoxClassExprConverter(term, SkolemStrategy.None)
+  def apply(
+    term : Term = Variable.create("x"),
+    skolem : SkolemStrategy = SkolemStrategy.None,
+    unsafe : List[OWLObjectPropertyExpression] = List()
+  ) : RDFoxClassExprConverter =
+          new RDFoxClassExprConverter(term, skolem, unsafe)
 
   def merge(rules : List[RDFoxRuleShards]) : RDFoxRuleShards = {
     rules.foldLeft(RDFoxRuleShards(List(),List())) {
@@ -31,7 +34,7 @@ object RDFoxClassExprConverter {
 
 } // object RDFoxClassExprConverter
 
-class RDFoxClassExprConverter(term : Term, skolem : SkolemStrategy)
+class RDFoxClassExprConverter(term : Term, skolem : SkolemStrategy, unsafe : List[OWLObjectPropertyExpression])
   extends OWLClassExpressionVisitorEx[RDFoxRuleShards]
 {
 
@@ -46,7 +49,7 @@ class RDFoxClassExprConverter(term : Term, skolem : SkolemStrategy)
   // OWLObjectIntersectionOf
   override
   def visit(expr : OWLObjectIntersectionOf) : RDFoxRuleShards = {
-    val visitor = new RDFoxClassExprConverter(term,skolem)
+    val visitor = new RDFoxClassExprConverter(term, skolem, unsafe)
     // TODO: maybe using `flatMap` instead of `merge` + `map` works as well
         RDFoxClassExprConverter.merge (
       expr.asConjunctSet.asScala.toList
@@ -75,22 +78,33 @@ class RDFoxClassExprConverter(term : Term, skolem : SkolemStrategy)
     // TODO: variables needs to be handled at visitor level. Hardcoding
     // the name of the varibles might lead to errors for complex cases.
     val y = Variable.create("y")
-    val (fun,term1) = skolem match {
-        case SkolemStrategy.None => (List(),y)
-        case SkolemStrategy.Constant(c) => (List(), Literal.create(c, Datatype.IRI_REFERENCE))
+    val prop = expr.getProperty()
+    // Computes the result of rule skolemization. Depending on the used 
+    // technique it might involve the introduction of additional atoms,
+    // and/or fresh constants and variables.
+    val (head, body, term1) = skolem match {
+        case SkolemStrategy.None => (List(), List(), y)
+        case SkolemStrategy.Constant(c) => (List(), List(), Literal.create(c, Datatype.IRI_REFERENCE))
+        case SkolemStrategy.ConstantRSA(c) => {
+          val lit = Literal.create(c, Datatype.IRI_REFERENCE)
+          if (unsafe.contains(prop))
+            (List(Atom.create(TupleTableName.create("internal:PE"),term,lit), Atom.create(TupleTableName.create("internal:U"),lit)), List(), lit)
+          else 
+            (List(), List(), lit)
+        }
         case SkolemStrategy.Standard(f) => 
           // At the time of writing the RDFox library does not have a
           // particular class for the "SKOLEM" operator and it is instead
-          // a simple builtin function with a special name.
-          (List(BindAtom.create(BuiltinFunctionCall.create("SKOLEM",term),y)),y)
+          // a simple builtin function with a "special" name.
+          (List(),List(BindAtom.create(BuiltinFunctionCall.create("SKOLEM",term),y)),y)
     }
-    val classVisitor = new RDFoxClassExprConverter(term1,skolem)
+    val classVisitor = new RDFoxClassExprConverter(term1, skolem, unsafe)
     val classResult = expr.getFiller.accept(classVisitor)
     val propertyVisitor = new RDFoxPropertyExprConverter(term, term1, skolem)
     val propertyResult = expr.getProperty.accept(propertyVisitor)
     RDFoxRuleShards(
-      classResult.res ++ propertyResult,
-      fun ++ classResult.ext
+      classResult.res ++ propertyResult ++ head,
+      classResult.ext ++ body
     )
   }
 
@@ -100,7 +114,7 @@ class RDFoxClassExprConverter(term : Term, skolem : SkolemStrategy)
     // TODO: again, no hardcoded variables
     val vars = List(Variable.create("y"),Variable.create("z"))
     val classResult = RDFoxClassExprConverter.merge(
-      vars.map(new RDFoxClassExprConverter(_,skolem))
+      vars.map(new RDFoxClassExprConverter(_,skolem, unsafe))
           .map(expr.getFiller.accept(_))
     )
     val propertyResult =