fix cycle detection

CupPlugin/src/de/tum/in/www2/cupplugin/views/CupConflictsView.java

@@ -86,6 +86,9 @@ public class CupConflictsView extends FailableView implements ICupEditorPageVisi
 	private PrecedenceToInsert currentPrecs;
 
 	class PrecedenceToInsert {
+		//TODO: The user can insert edges that contradict the thing we wanted in the end => Doesn't crash on cyclic
+		// Occurs because the first terminal is not inserted
+		
 		//TODO: Can I do this? Does the terminal class properly implement all the required things?
 		private HashMap<terminal,Precedence.Type> precs = new HashMap<>();
 		
@@ -93,6 +96,9 @@ public class CupConflictsView extends FailableView implements ICupEditorPageVisi
 		// precedence than a)
 		private HashMap<terminal,Set<terminal>> edges = new HashMap<>();
 		
+		// These need to be inserted whenever an edge that contains the key is to be inserted
+		private HashMap<terminal,Set<terminal>> speculativeEdges = new HashMap<>();
+		
 		private int tarjanIndex;
 		private HashMap<terminal,TarjanNodeInfo> tarjanNodeInfos;
 		private Stack<terminal> tarjanStack;
@@ -131,11 +137,16 @@ public class CupConflictsView extends FailableView implements ICupEditorPageVisi
 		}
 		
 		// Add with non-set assoc
-		public void add(terminal t){
+		public void add(terminal t,terminal other){
 			// We use NoPrec as a placeholder
 			precs.put(t, Precedence.Type.NoPrec);
 			edges.put(t, new HashSet<>());
 			
+			HashSet<terminal> spec = new HashSet<>();
+			spec.add(t);
+			speculativeEdges.put(other,spec);
+			
+			
 			for(ConflictPanel c : conflictPanels){
 				c.markIfAffected(this);
 			}
@@ -154,9 +165,19 @@ public class CupConflictsView extends FailableView implements ICupEditorPageVisi
 				edges.put(lower, new HashSet<>());
 			}
 			
+			// Insert all speculative edges that are outgoing from the current node
+			// we need those now
+			if(speculativeEdges.containsKey(higher)){
+				edges.get(higher).addAll(speculativeEdges.get(higher));
+			}
+			
 			// Insert edge
 			edges.get(lower).add(higher);
 			
+			if(!isAcylic()){
+				throw new IllegalStateException("Horrible  things lurk here");
+			}
+			
 			for(ConflictPanel c : conflictPanels){
 				c.markIfAffected(this);
 			}
@@ -223,8 +244,24 @@ public class CupConflictsView extends FailableView implements ICupEditorPageVisi
 		
 		
 		private boolean hasPrecedence(terminal t,terminal over){
+			if(!precs.containsKey(t) && !precs.containsKey(over)){
+				return false;
+			}
+			
+			if(precs.containsKey(t) && !precs.containsKey(over)){
+				return true;
+			}
+			if(!precs.containsKey(t) && precs.containsKey(over)){
+				return false;
+			}
+			// Hereafter we know that both are in there
+			
+			
 			// This works because we have guarantee that the graph is a DAG
 			HashSet<terminal> toCheck = new HashSet<>();
+			if(edges.get(over).size() == 0){
+				return true;
+			}
 			toCheck.addAll(edges.get(over));
 			
 			// TODO:Sure ?
@@ -726,7 +763,7 @@ public class CupConflictsView extends FailableView implements ICupEditorPageVisi
 					return;
 				}
 				
-				if(currentPrecs.isActive()) {
+				if(currentPrecs != null && currentPrecs.isActive()) {
 					// That should not happen, if we are inside a connected conflict, button is disabled
 					return;
 				}