add comments for better understanding

src/Algorithms/Animated/BK/Compaction.java

@@ -31,8 +31,8 @@ public class Compaction implements AlgorithmStage{
 	private LayeredGraphNode graph;
 	private int vIndex;
 	
-	private ArrayList< StackFrame > stack;
-	private ArrayList< BackwardAction > actions;
+	private ArrayList< StackFrame > stack; // TODO: evtl richtigen "Stack" benutzen
+	private ArrayList< BackwardAction > actions; // TODO: evtl richtigen "Stack" benutzen
 	private LayoutType layout;
 	
 	public Compaction( LayeredGraphNode graph, LayoutType layout )
@@ -40,7 +40,7 @@ public class Compaction implements AlgorithmStage{
 	    this.layout = layout;
 		this.graph = graph;
 		state = CompactionState.PLACE_BLOCKS;
-		stack = new ArrayList<>();
+		stack = new ArrayList<>(); // der call-stack des rekursiven algorithmus
 		vIndex = 0;
 		actions = new ArrayList<>();
 	}
@@ -56,13 +56,15 @@ public class Compaction implements AlgorithmStage{
 	@Override
 	public StageStatus forwardStep() {
 		int acSize = actions.size();
-		if( state == CompactionState.PLACE_BLOCKS )
+		if( state == CompactionState.PLACE_BLOCKS ) // blöcke platzieren
 		{
-			if( stack.size() == 0 )
+			if( stack.size() == 0 ) // äußere schleife, placeblocks bisher nicht aufgerufen
 			{
 				ArrayList< LayeredGraphNode > nodes = graph.getContainedNodes();
-				boolean found = false;
-				int oldVIndex = vIndex;
+				boolean found = false; // knoten mit v = root[v] gefunden?
+				int oldVIndex = vIndex; // nötig für "undo"
+				
+				// suche knoten mit v = root[v] und undefiniertem x-Wert
 				for( ; vIndex < nodes.size(); vIndex++ )
 				{
 					if( nodes.get( vIndex ).isXUndefined( layout ) && nodes.get( vIndex ) == nodes.get( vIndex ).getRoot( layout ) )
@@ -71,8 +73,11 @@ public class Compaction implements AlgorithmStage{
 						break;
 					}
 				}
+				
+				// kein knoten gefunden
 				if( !found )
 				{
+				    // wechsele in die phase des Blöckeshiftens
 					state = CompactionState.APPLY_SHIFT;
 					vIndex = 0;
 					actions.add( 0, ()-> {
@@ -80,15 +85,17 @@ public class Compaction implements AlgorithmStage{
 						state = CompactionState.PLACE_BLOCKS;
 					} );
 				}
-				else
+				else // Knoten gefunden
 				{
-					StackFrame f = new StackFrame();
+					StackFrame f = new StackFrame(); // enthält lokale variablen
 					f.v = nodes.get( vIndex );
-					double oldX = f.v.getX( layout );
+					double oldX = f.v.getX( layout ); // nötig für "undo"
 					f.v.setX( 0, true, layout );
-					f.v.setSelected( layout );
+					f.v.setSelected( layout ); // zeige knoten als aktiven knoten an
 					f.w = f.v;
 					stack.add( 0, f );
+					
+					// die "undo"-action
 					actions.add( 0, ()-> {
 						stack.get( 0 ).v.setX( oldX, false, layout );
 						stack.get( 0 ).v.setSelected( layout );
@@ -98,23 +105,27 @@ public class Compaction implements AlgorithmStage{
 					});
 				}
 			}
-			else
+			else // zurzeit innerhalb einer placeblock methode
 			{
 				StackFrame sf = stack.get( 0 );
-				if( sf.u == null )
+				if( sf.u == null ) // zu beginn der placeblock methode
 				{
-					if( graph.getContainedLayers().get( sf.w.getLayer() ).indexOf( sf.w ) >= 1 )
+					if( graph.getContainedLayers().get( sf.w.getLayer() ).indexOf( sf.w ) >= 1 ) // if pos[w] > 1"
 					{
+					    
 						sf.u = graph.getContainedLayers().get( sf.w.getLayer() ).get( graph.getContainedLayers().get( sf.w.getLayer() ).indexOf( sf.w ) - 1 ).getRoot( layout );
-						if( sf.u.isXUndefined( layout ) )
-						{
-							StackFrame nsf = new StackFrame();
+						
+						if( sf.u.isXUndefined( layout ) ) // nötig placeblock aufzurufen?
+						{// ja
+							StackFrame nsf = new StackFrame(); // enthält lokale variablen
 							nsf.v = sf.u;
-							double oldX = nsf.v.getX( layout );
+							double oldX = nsf.v.getX( layout ); // nötig für "undo"
 							nsf.v.setX( 0, true, layout );
-							nsf.v.setSelected( layout );
+							nsf.v.setSelected( layout ); // zeige knoten als aktiven knoten an
 							nsf.w = nsf.v;
 							stack.add( 0, nsf );
+		                    
+		                    // die "undo"-action
 							actions.add( 0, ()-> {
 								stack.get( 0 ).v.setX( oldX, false, layout );
 								stack.get( 0 ).v.setSelected( layout );
@@ -122,21 +133,23 @@ public class Compaction implements AlgorithmStage{
 								stack.get( 0 ).u = null;
 							});
 						}
-						else
+						else // nein
 						{
-							sf.u.setSelected( layout );
+						    // tue nix
+							sf.u.setSelected( layout ); 
 							actions.add( 0, ()-> {
 								stack.get( 0 ).u = null;
 							});
 						}
 					}
-					else
-					{
+					else 
+					{ // w = align[w]
 						LayeredGraphNode oldW = sf.w;
 						sf.v.setSelected( layout );
 						sf.w = sf.w.getAlignedTo( layout );
-						if( sf.w == sf.v )
-						{
+						
+						if( sf.w == sf.v ) // schleifenabbruchbedingung
+						{ //abbrechen, placeblock beendet
 							stack.remove( 0 );
 							actions.add( 0, ()-> {
 								stack.add( 0, sf );
@@ -145,7 +158,7 @@ public class Compaction implements AlgorithmStage{
 							});
 						}
 						else
-						{
+						{ //nur "undo aktion" hinzufügen
 							actions.add( 0, ()-> {
 								sf.w = oldW;
 								sf.v.setSelected( layout );
@@ -153,26 +166,39 @@ public class Compaction implements AlgorithmStage{
 						}
 					}	
 				}
-				else
+				else // der Teil nach "placeBlock(u)"
 				{
-					LayeredGraphNode oldSink = sf.v.getSink( layout );
-					if( sf.v.getSink( layout ) == sf.v )
-						sf.v.setSink( sf.u.getSink( layout ), layout );
+				    // alte Werte merken für undo
+					LayeredGraphNode oldSink = sf.v.getSink( layout );					
 					LayeredGraphNode sinkOfU = sf.u.getSink( layout );
 					double oldShift = sinkOfU.getShift( layout );
 					double oldX = sf.v.getX( layout );
 					boolean oldDef = !sf.v.isXUndefined( layout );
+					
+					// v für visualisierung markieren
 					sf.v.setSelected( layout );
-					if( sf.v.getSink( layout ) != sf.u.getSink( layout ) )
-						sf.u.getSink( layout ).setShift( Math.min( sf.u.getSink( layout ).getShift( layout ), sf.v.getX( layout ) - sf.u.getX( layout ) - calcSpacing() ), layout );
+                    
+                    if( sf.v.getSink( layout ) == sf.v ) // sink[v] = v?
+                        sf.v.setSink( sf.u.getSink( layout ), layout ); // sink[v] := sink[u]
+
+					if( sf.v.getSink( layout ) != sf.u.getSink( layout ) ) // sink[v] != sink [u]?
+						sf.u.getSink( layout ).setShift( // shift[sink[u]] =
+						  Math.min( sf.u.getSink( layout ).getShift( layout ),  // min(shift[sink[u]]
+						          sf.v.getX( layout ) - sf.u.getX( layout ) - calcSpacing() ), layout ); // y_v - y_u - s
 					else
+					    // y_v = max {y_v, y_u + s}
 						sf.v.setX( Math.max( sf.v.getX( layout ), sf.u.getX( layout ) + calcSpacing() ), true, layout );
+					
+
+                    // alte Werte merken für undo
 					LayeredGraphNode oldW = sf.w;
-					sf.w = sf.w.getAlignedTo( layout );
-					LayeredGraphNode oldU = sf.u;
-					sf.u = null;
-					if( sf.w == sf.v )
-					{
+                    LayeredGraphNode oldU = sf.u;
+                    
+					sf.w = sf.w.getAlignedTo( layout ); // w = align[w]
+					sf.u = null; // u wird nächsten schleifendurchlauf neu gesetzt
+					
+					if( sf.w == sf.v ) // schleifenabbruchbedingung
+					{ //abbrechen, placeblock beendet  
 						stack.remove( 0 );
 						actions.add( 0, ()-> {
 							stack.add( 0, sf );
@@ -185,7 +211,7 @@ public class Compaction implements AlgorithmStage{
 						});
 					}
 					else
-					{
+					{ //nur "undo aktion" hinzufügen
 						actions.add( 0, ()-> {
 							stack.get( 0 ).v.setSink(  oldSink, layout );
 							sinkOfU.setShift( oldShift, layout );