1 files changed, 108 insertions, 0 deletions
diff --git a/src/jrummikub/ai/fdsolver/constraint/IfConstraint.java b/src/jrummikub/ai/fdsolver/constraint/IfConstraint.java
new file mode 100644
index 0000000..802acc2
--- /dev/null
+++ b/src/jrummikub/ai/fdsolver/constraint/IfConstraint.java
@@ -0,0 +1,108 @@
+package jrummikub.ai.fdsolver.constraint;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import java.util.concurrent.locks.Condition;
+
+
+import jrummikub.ai.fdsolver.Constraint;
+import jrummikub.ai.fdsolver.Propagator;
+import jrummikub.ai.fdsolver.Satisfiability;
+import jrummikub.ai.fdsolver.Var;
+
+public class IfConstraint implements Constraint {
+	Var<Boolean> condition;
+	Constraint child;
+	Collection<Var<?>> vars;
+	boolean negateCond;
+
+	public IfConstraint(boolean negateCond, Var<Boolean> condition, Constraint child) {
+		this.condition = condition;
+		this.child = child;
+		this.negateCond = negateCond;
+		vars = new ArrayList<Var<?>>();
+		vars.addAll(child.getWatchedVars());
+		vars.add(condition);
+	}
+	
+	@Override
+	public Collection<Var<?>> getWatchedVars() {
+		return vars;
+	}
+
+	private class IfPropagator implements Propagator {
+		Propagator child;
+		Collection<Var<?>> vars;
+		public IfPropagator(Propagator child) {
+			this.child = child;
+			vars = new ArrayList<Var<?>>();
+			vars.addAll(child.getWatchedVars());
+			vars.add(condition);
+		}
+		
+		@Override
+		public Collection<Var<?>> getWatchedVars() {
+			return vars;
+		}
+
+		@Override
+		public void propagate() {
+			if(condition.getRange().contains(negateCond)) {
+				return;
+			}
+			child.propagate();
+		}
+	}
+	
+	private class FailPropagator implements Propagator {
+		@Override
+		public Collection<Var<?>> getWatchedVars() {
+			return child.getWatchedVars();
+		}
+
+		@Override
+		public void propagate() {
+			if (child.getSatisfiability() == Satisfiability.UNSAT) {
+				condition.invalidate(!negateCond);
+			}
+		}
+	}
+	
+	@Override
+	public Collection<Propagator> getPropagators(boolean negate) {
+		List<Propagator> props = new ArrayList<Propagator>();
+		if (negate) {
+			props.add(new FilterPropagator<Boolean>(new Filter<Boolean>() {
+				@Override
+				public boolean accept(Boolean value) {
+					return value ^ negateCond;
+				}
+			}, condition));
+			props.addAll(child.getPropagators(true));
+		} else {
+			for (Propagator p : child.getPropagators(false)) {
+				props.add(new IfPropagator(p));
+			}
+			props.add(new FailPropagator());
+		}
+		return props;
+	}
+
+	@Override
+	public Satisfiability getSatisfiability() {
+		if (condition.getRange().contains(negateCond)) {
+			if (condition.getRange().size() == 1) {
+				return Satisfiability.TAUT;
+			} else {
+				if (child.getSatisfiability() == Satisfiability.TAUT) {
+					return Satisfiability.TAUT;
+				} else {
+					return Satisfiability.SAT;
+				}
+			}
+		}
+		return child.getSatisfiability();
+	}
+	
+}