1 files changed, 67 insertions, 0 deletions
diff --git a/src/jrummikub/ai/fdsolver/constraint/ComparatorConstraint.java b/src/jrummikub/ai/fdsolver/constraint/ComparatorConstraint.java
new file mode 100644
index 0000000..24e7ecf
--- /dev/null
+++ b/src/jrummikub/ai/fdsolver/constraint/ComparatorConstraint.java
@@ -0,0 +1,67 @@
+package jrummikub.ai.fdsolver.constraint;
+
+import static jrummikub.ai.fdsolver.Satisfiability.*;
+
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Comparator;
+
+import jrummikub.ai.fdsolver.Constraint;
+import jrummikub.ai.fdsolver.Propagator;
+import jrummikub.ai.fdsolver.Satisfiability;
+import jrummikub.ai.fdsolver.Var;
+
+public class ComparatorConstraint<T> implements Constraint {
+	Var<T> x, y;
+	Comparator<T> comparator, reverseComparator;
+	ComparatorPropagator<T> trueX, trueY, falseX, falseY;
+	boolean allowEqual;
+	
+	ComparatorConstraint(final Comparator<T> comparator, boolean allowEqual, Var<T> x, Var<T> y) {
+		this.x = x;
+		this.y = y;
+		this.comparator = comparator;
+		this.allowEqual = allowEqual;
+		reverseComparator = new Comparator<T>() {
+			@Override
+			public int compare(T o1, T o2) {
+				return comparator.compare(o2, o1);
+			}
+		};
+		trueX = new ComparatorPropagator<T>(comparator, allowEqual, x, y);
+		trueY = new ComparatorPropagator<T>(reverseComparator, allowEqual, y, x);
+		falseX = new ComparatorPropagator<T>(reverseComparator, !allowEqual, x, y);
+		falseY = new ComparatorPropagator<T>(comparator, !allowEqual, y, x);
+	}
+	
+	@Override
+	public Collection<Var<?>> getWatchedVars() {
+		return Arrays.<Var<?>>asList(x,y);
+	}
+
+	@Override
+	public Collection<Propagator> getPropagators(boolean negate) {
+		if (negate) {
+			return Arrays.<Propagator>asList(falseX,falseY);
+		} else {
+			return Arrays.<Propagator>asList(trueX,trueY);
+		}
+	}
+
+	@Override
+	public Satisfiability getSatisfiability() {
+		T maxX = Collections.max(x.getRange(), comparator);
+		T minY = Collections.min(y.getRange(), comparator);
+		if (comparator.compare(maxX, minY) < (allowEqual ? 1 : 0)) {
+			return TAUT;
+		}
+		T minX = Collections.min(x.getRange(), comparator);
+		T maxY = Collections.max(y.getRange(), comparator);
+		if (comparator.compare(maxY, minX) < (allowEqual ? 0 : 1)) {
+			return UNSAT;
+		}
+		return SAT;
+	}
+
+}