prmr#416 Refactor constraint about edge end in sequence diagram

The case where trying to create a constructor edge was implemented as a
special case in constraints, where the constraint was only added to the
constraint set if the call could be a legal constructor call. This
divergence from the design, where all constraints are stored in a set,
was creating an obstacle to the future improvement of the constraint
management. With this change, all constraints are implemented as
predicates.

src/ca/mcgill/cs/jetuml/diagram/builder/SequenceDiagramBuilder.java

@@ -72,13 +72,9 @@ protected ConstraintSet getAdditionalEdgeConstraints(Edge pEdge, Node pStart, No
 				EdgeConstraints.maxEdges(pEdge, pStart, pEnd, aDiagram, 1),
 				SequenceDiagramEdgeConstraints.noEdgesFromParameterTop(pStart, pStartPoint),
 				SequenceDiagramEdgeConstraints.returnEdge(pEdge, pStart, pEnd, aDiagram),
-				SequenceDiagramEdgeConstraints.singleEntryPoint(pEdge, pStart, aDiagram)
+				SequenceDiagramEdgeConstraints.singleEntryPoint(pEdge, pStart, aDiagram),
+				SequenceDiagramEdgeConstraints.callEdgeEnd(pEdge, pStart, pEnd, pEndPoint, aDiagram)
 			);
-		if( !canCreateConstructorCall(pStartPoint, pEndPoint) )
-		{
-			// The edge could not land on the top rectangle of ImplicitParameterNode if cannot create constructor call
-			constraintSet.merge( new ConstraintSet(SequenceDiagramEdgeConstraints.callEdgeEnd(pEdge, pEnd, pEndPoint)) );
-		}
 		return constraintSet;
 	}
 

src/ca/mcgill/cs/jetuml/diagram/builder/constraints/SequenceDiagramEdgeConstraints.java

@@ -73,18 +73,26 @@ public static Constraint returnEdge(Edge pEdge, Node pStart, Node pEnd, Diagram
 	}
 
 	/*
-	 * Call edges that land on a parameter node must land on the lifeline part.
+	 * Call edges that land on a parameter node must land on the lifeline part,
+	 * except if it is allowed to create a constructor.
 	 */
-	public static Constraint callEdgeEnd(Edge pEdge, Node pEndNode, Point pEndPoint)
+	public static Constraint callEdgeEnd(Edge pEdge, Node pStartNode, Node pEndNode, Point pEndPoint, Diagram pDiagram)
 	{
 		return ()->
 		{
 			return !(pEdge.getClass() == CallEdge.class && 
 					 pEndNode.getClass() == ImplicitParameterNode.class &&
-							 IMPLICIT_PARAMETER_NODE_VIEWER.getTopRectangle(pEndNode).contains(pEndPoint));
+							 IMPLICIT_PARAMETER_NODE_VIEWER.getTopRectangle(pEndNode).contains(pEndPoint) && 
+							 	!canCreateConstructor(pStartNode, pEndNode, pDiagram, pEndPoint));
 		};
 	}
 
+	private static boolean canCreateConstructor(Node pStartNode, Node pEndNode, Diagram pDiagram, Point pEndPoint)
+	{
+		return 	(pStartNode instanceof ImplicitParameterNode || pStartNode instanceof CallNode) && 
+				new ControlFlow(pDiagram).canCreateConstructedObject(pEndNode, pEndPoint);
+	}
+
 	/*
 	 * It's only legal to start an interaction on a parameter node if there are no existing activations
 	 * in the diagram.

test/ca/mcgill/cs/jetuml/diagram/builder/constraints/TestSequenceDiagramEdgeConstraints.java

@@ -156,28 +156,28 @@ public void testreturnEdgeValid()
 	public void testCallEdgeEndNotCallEdge()
 	{
 		createDiagram();
-		assertTrue(SequenceDiagramEdgeConstraints.callEdgeEnd(aReturnEdge, aCallNode2, new Point(10,10)).satisfied());
+		assertTrue(SequenceDiagramEdgeConstraints.callEdgeEnd(aReturnEdge, aCallNode2, aCallNode1, new Point(10,10), aDiagram).satisfied());
 	}	
 
 	@Test
 	public void testCallEdgeEndEndNotParameter()
 	{
 		createDiagram();
-		assertTrue(SequenceDiagramEdgeConstraints.callEdgeEnd(aCallEdge, aCallNode2, new Point(10,10)).satisfied());
+		assertTrue(SequenceDiagramEdgeConstraints.callEdgeEnd(aCallEdge, aCallNode2, aCallNode1, new Point(10,10), aDiagram).satisfied());
 	}	
 
 	@Test
 	public void testCallEdgeEndEndOnLifeLine()
 	{
 		createDiagram();
-		assertTrue(SequenceDiagramEdgeConstraints.callEdgeEnd(aCallEdge, aParameter2, new Point(0,85)).satisfied());
+		assertTrue(SequenceDiagramEdgeConstraints.callEdgeEnd(aCallEdge, aParameter2, aCallNode1, new Point(0,85), aDiagram).satisfied());
 	}	
 
 	@Test
 	public void testCallEdgeEndEndOnTopRectangle()
 	{
 		createDiagram();
-		assertFalse(SequenceDiagramEdgeConstraints.callEdgeEnd(aCallEdge, aParameter2, new Point(0,5)).satisfied());
+		assertTrue(SequenceDiagramEdgeConstraints.callEdgeEnd(aCallEdge, aParameter2, aCallNode1, new Point(0,5), aDiagram).satisfied());
 	}	
 
 	@Test