From 9ce65c5a963b03ee97fe9cb6c5aa65a3c04a80a8 Mon Sep 17 00:00:00 2001
From: yzhou <yujiao.zhou@gmail.com>
Date: Tue, 21 Apr 2015 10:34:27 +0100
Subject: initial version

---
 .../ac/ox/cs/pagoda/constraints/UnaryBottom.java   | 67 ++++++++++++++++++++++
 1 file changed, 67 insertions(+)
 create mode 100644 src/uk/ac/ox/cs/pagoda/constraints/UnaryBottom.java

(limited to 'src/uk/ac/ox/cs/pagoda/constraints/UnaryBottom.java')

diff --git a/src/uk/ac/ox/cs/pagoda/constraints/UnaryBottom.java b/src/uk/ac/ox/cs/pagoda/constraints/UnaryBottom.java
new file mode 100644
index 0000000..5339c50
--- /dev/null
+++ b/src/uk/ac/ox/cs/pagoda/constraints/UnaryBottom.java
@@ -0,0 +1,67 @@
+package uk.ac.ox.cs.pagoda.constraints;
+
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.LinkedList;
+import java.util.Set;
+
+import org.semanticweb.HermiT.model.Atom;
+import org.semanticweb.HermiT.model.AtomicConcept;
+import org.semanticweb.HermiT.model.DLClause;
+import org.semanticweb.HermiT.model.Individual;
+import org.semanticweb.HermiT.model.Term;
+import org.semanticweb.HermiT.model.Variable;
+
+public class UnaryBottom implements BottomStrategy {
+	
+	@Override
+	public Collection<DLClause> process(Collection<DLClause> clauses) {
+		Collection<DLClause> ret = new LinkedList<DLClause>(); 
+		for (DLClause clause: clauses) 
+			if (clause.getHeadLength() == 0) {
+				ret.add(DLClause.create(getEmptyHead(pickRepresentative(clause.getBodyAtoms())), clause.getBodyAtoms()));
+			}
+			else 
+				ret.add(clause); 
+		return ret;
+	}
+
+	protected Term pickRepresentative(Atom[] atoms) {
+		Term rep = null; 
+		Set<Variable> vars = new HashSet<Variable>(); 
+		for (Atom atom: atoms) {
+			atom.getVariables(vars);
+			for (Variable v: vars)
+				if (rep == null || ((Variable) rep).getName().compareTo(v.getName()) > 0)
+					rep = v;
+			vars.clear(); 
+		}
+		if (rep != null) return rep; 
+		
+		Set<Individual> inds = new HashSet<Individual>(); 
+		for (Atom atom: atoms) {
+			atom.getIndividuals(inds);
+			for (Individual i: inds)
+				if (rep == null || ((Individual) rep).getIRI().compareTo(i.getIRI()) > 0)
+					rep = i;
+			inds.clear();
+		}
+		
+		return rep;
+	}
+
+	@Override
+	public boolean isBottomRule(DLClause clause) {
+		return clause.getHeadLength() == 1 && clause.getHeadAtom(0).getDLPredicate().equals(AtomicConcept.NOTHING);
+	}
+
+	public Atom[] getEmptyHead(Term t) {
+		return new Atom[] {Atom.create(AtomicConcept.NOTHING, t)};
+	}
+
+	@Override
+	public int getBottomNumber() {
+		return 1;
+	}
+
+}
-- 
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