AllBottom: simplify and fix meetWith

src/heros/edgefunc/AllBottom.java

@@ -4,53 +4,52 @@
  * are made available under the terms of the GNU Lesser Public License v2.1
  * which accompanies this distribution, and is available at
  * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
- * 
+ *
  * Contributors:
- *     Eric Bodden - initial API and implementation
+ *	 Eric Bodden - initial API and implementation
  ******************************************************************************/
 package heros.edgefunc;
 
 import heros.EdgeFunction;
 
 
 public class AllBottom<V> implements EdgeFunction<V> {
-	
+
 	private final V bottomElement;
 
 	public AllBottom(V bottomElement){
 		this.bottomElement = bottomElement;
-	} 
+	}
 
+	@Override
 	public V computeTarget(V source) {
 		return bottomElement;
 	}
 
+	@Override
 	public EdgeFunction<V> composeWith(EdgeFunction<V> secondFunction) {
 		if (secondFunction instanceof EdgeIdentity)
 			return this;
 		return secondFunction;
 	}
 
+	// The meet (greatest lower bound) of bottom with anything is bottom
+	@Override
 	public EdgeFunction<V> meetWith(EdgeFunction<V> otherFunction) {
-		if(otherFunction == this || otherFunction.equalTo(this)) return this;
-		if(otherFunction instanceof AllTop) {
-			return this;
-		}
-		if(otherFunction instanceof EdgeIdentity) {
-			return this;
-		}
-		throw new IllegalStateException("unexpected edge function: "+otherFunction);
+		return this;
 	}
 
+	@Override
 	public boolean equalTo(EdgeFunction<V> other) {
 		if(other instanceof AllBottom) {
 			@SuppressWarnings("rawtypes")
 			AllBottom allBottom = (AllBottom) other;
 			return allBottom.bottomElement.equals(bottomElement);
-		}		
+		}
 		return false;
 	}
-
+
+	@Override
 	public String toString() {
 		return "allbottom";
 	}