1 files changed, 134 insertions, 0 deletions
diff --git a/src/jrummikub/ai/fdsolver/constraint/IndexConstraint.java b/src/jrummikub/ai/fdsolver/constraint/IndexConstraint.java
new file mode 100644
index 0000000..999924f
--- /dev/null
+++ b/src/jrummikub/ai/fdsolver/constraint/IndexConstraint.java
@@ -0,0 +1,134 @@
+package jrummikub.ai.fdsolver.constraint;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.List;
+
+import jrummikub.ai.fdsolver.Constraint;
+import jrummikub.ai.fdsolver.Propagator;
+import jrummikub.ai.fdsolver.Satisfiability;
+import jrummikub.ai.fdsolver.Var;
+
+public class IndexConstraint<T> implements Constraint {
+	Var<T> target;
+	Var<Integer> index;
+	List<Var<T>> list;
+	Collection<Var<?>> vars = new ArrayList<Var<?>>();
+	Collection<Var<?>> varsNoTarget = new ArrayList<Var<?>>();
+	Collection<Var<?>> varsNoIndex = new ArrayList<Var<?>>();
+
+	public IndexConstraint(Var<T> target, Var<Integer> index, List<Var<T>> list) {
+		this.target = target;
+		this.index = index;
+		this.list = list;
+		vars.addAll(list);
+		vars.add(index);
+		vars.add(target);
+		varsNoTarget.addAll(list);
+		varsNoTarget.add(index);
+		varsNoIndex.addAll(list);
+		varsNoIndex.add(target);
+	}
+
+	@Override
+	public Collection<Var<?>> getWatchedVars() {
+		return vars;
+	}
+
+	private class UnionProp implements Propagator {
+		@Override
+		public Collection<Var<?>> getWatchedVars() {
+			return varsNoTarget;
+		}
+
+		@Override
+		public void propagate() {
+			HashSet<T> union = new HashSet<T>();
+			for (int i : index.getRange()) {
+				union.addAll(list.get(i).getRange());
+			}
+			for (Iterator<T> i = target.iterator(); i.hasNext();) {
+				T val = i.next();
+				if (!union.contains(val)) {
+					i.remove();
+				}
+			}
+		};
+	}
+
+	private class IndexProp implements Propagator {
+		@Override
+		public Collection<Var<?>> getWatchedVars() {
+			return varsNoIndex;
+		}
+
+		@Override
+		public void propagate() {
+			for (Iterator<Integer> i = index.iterator(); i.hasNext();) {
+				int id = i.next();
+				HashSet<T> range = new HashSet<T>(target.getRange());
+				range.retainAll(list.get(id).getRange());
+				if (range.isEmpty()) {
+					i.remove();
+				}
+			}
+		}
+	}
+
+	private class VarProp implements Propagator {
+		@Override
+		public Collection<Var<?>> getWatchedVars() {
+			return Arrays.asList(target, index);
+		}
+
+		@Override
+		public void propagate() {
+			if (index.getRange().size() != 1)
+				return;
+			int id = index.getValue();
+			Var<T> var = list.get(id);
+			for(Iterator<T> i = var.iterator(); i.hasNext();) {
+				if (!target.getRange().contains(i.next())) {
+					i.remove();
+				}
+			}
+		}
+
+	}
+
+	@Override
+	public Collection<Propagator> getPropagators(boolean negate) {
+		if (negate) {
+			return Collections.emptyList();
+		}
+		return Arrays.<Propagator> asList(new UnionProp(), new IndexProp(), new VarProp());
+	}
+
+	@Override
+	public Satisfiability getSatisfiability() {
+		HashSet<T> union = new HashSet<T>();
+		for (int i : index.getRange()) {
+			union.addAll(list.get(i).getRange());
+		}
+		boolean isSat = false;
+		for (T val : target.getRange()) {
+			if (union.contains(val)) {
+				isSat = true;
+				break;
+			}
+		}
+		if (!isSat) {
+			return Satisfiability.UNSAT;
+		} else {
+			if (union.size() == 1 && target.getRange().size() == 1) {
+				return Satisfiability.TAUT;
+			} else {
+				return Satisfiability.SAT;
+			}
+		}
+	}
+}