Implement model 1A

src/edu/kit/informatik/model/Train.java

@@ -256,10 +256,14 @@ public final class Train {
      * @param nextPosition position to move train to
      */
     public void moveTo(final RailwayNetwork railNetwork, final Vector2D nextPosition) {
-        // make sure caller can not modiy internal state
-        position.addFirst(new Vector2D(nextPosition));
         Vector2D last = position.removeLast();
-        updateOccupiedRails(railNetwork, position.getFirst(), last, position.getLast());
+        if (nextPosition != null) {
+            // not derailing
+            position.addFirst(new Vector2D(nextPosition));
+            updateOccupiedRails(railNetwork, position.getFirst(), last, position.getLast());
+        } else {
+            updateOccupiedRails(railNetwork, null, last, position.getLast());
+        }
     }
 
     /**
@@ -269,8 +273,14 @@ public final class Train {
      */
     public void moveBackTo(final RailwayNetwork railNetwork, final Vector2D rearPosition) {
         Vector2D last = position.removeFirst();
-        position.addLast(new Vector2D(rearPosition));
+        if (rearPosition != null) {
-        updateOccupiedRails(railNetwork, position.getLast(), last, position.getFirst());
+            // not derailing
+            position.addLast(new Vector2D(rearPosition));
+            updateOccupiedRails(railNetwork, position.getLast(), last, position.getFirst());
+        } else {
+            // derailing
+            updateOccupiedRails(railNetwork, null, last, position.getFirst());
+        }
     }
 
     /**
@@ -282,7 +292,7 @@ public final class Train {
      */
     private void updateOccupiedRails(final RailwayNetwork railNetwork, final Vector2D nextPosition,
                                      final Vector2D lastPosition, final Vector2D secondToLastPosition) {
-        if (nextPosition.equals(secondToLastPosition)) {
+        if (secondToLastPosition.equals(nextPosition)) {
             // we are moving in a loop, no need to update
             return;
         }
@@ -296,6 +306,10 @@ public final class Train {
             occupiedRails.clear();
         } // else: only touched rail
         // update occupied rails, adding next rail
+        if (nextPosition == null) {
+            // derailing
+            return;
+        }
         Rail nextRail = railNetwork.findContainingRail(nextPosition);
         if (nextRail != null) {
             occupiedRails.add(nextRail);

src/edu/kit/informatik/model/TrainManager.java

@@ -165,7 +165,9 @@ public final class TrainManager {
         // attempt to place train
         boolean placed = train.placeOn(railNetwork, position, direction);
         // check for collisions
-        if (placed && !getStaticCollisions().isEmpty()) {
+        List<Set<Train>> collisions = new ArrayList<>();
+        getStaticCollisions(collisions);
+        if (placed && !collisions.isEmpty()) { // TODO: implement 2B
             train.removeFromRails();
             return false;
         } else {
@@ -184,10 +186,9 @@ public final class TrainManager {
 
     /**
      * Get collisions of trains currently placed.
-     * @return list of collisions (never null, sometimes empty)
+     * @param collisions list of collisions (never null, sometimes empty)
      */
-    private List<HashSet<Train>> getStaticCollisions() {
+    private void getStaticCollisions(List<Set<Train>> collisions) {
-        List<HashSet<Train>> collisions = new ArrayList<>();
         int maxId = trains.keySet().stream().max(Integer::compareTo).orElse(0);
         for (int id1 = 1; id1 <= maxId; id1++) {
             Train train1 = trains.get(id1);
@@ -195,12 +196,21 @@ public final class TrainManager {
                 continue;
             }
             HashSet<Train> collision = new HashSet<>();
+            // check for same position
             IntStream.rangeClosed(id1 + 1, maxId)
                     .mapToObj(trains::get)
                     .filter(Objects::nonNull)
                     .filter(Train::isPlaced)
                     .filter(train1::touches)
                     .forEach(collision::add);
+            // check for rail collisions
+            Set<Rail> occupiedRails = train1.getOccupiedRails();
+            IntStream.rangeClosed(id1 + 1, maxId)
+                    .mapToObj(trains::get)
+                    .filter(Objects::nonNull)
+                    .filter(Train::isPlaced)
+                    .filter(train -> train.getOccupiedRails().stream().anyMatch(occupiedRails::contains))
+                    .forEach(collision::add);
             if (!collision.isEmpty()) {
                 // check for existing collision
                 Set<Train> otherCollision = collisions.stream()
@@ -215,7 +225,6 @@ public final class TrainManager {
                 }
             }
         }
-        return collisions;
     }
 
     /**
@@ -224,31 +233,21 @@ public final class TrainManager {
      */
     private List<Set<Train>> getCollisionsOfOneStep() {
         List<Set<Train>> collisions = new ArrayList<>();
-        Map<Train, Set<Rail>> occupiedRails = trains.values().stream().filter(Train::isPlaced)
-                .collect(Collectors.toMap(Function.identity(), Train::getOccupiedRails));
-        // perform step
-        Map<Train, Set<Rail>> nextOccupiedRails = new HashMap<>();
         trains.values().stream().filter(Train::isPlaced).forEach(train -> {
             Vector2D position = train.getFrontPosition();
             Vector2D direction = train.getDirection();
             Vector2D nextPosition = railNetwork.move(position, direction);
             if (nextPosition == null
                     || train.isOnPosition(nextPosition) && !train.getRearPosition().equals(train.getFrontPosition())) {
+                train.moveTo(railNetwork, nextPosition);
                 collisions.add(new HashSet<>(Arrays.asList(train)));
-                train.removeFromRails();
-                // see https://ilias.studium.kit.edu/goto.php?target=frm_996924_138875&client_id=produktiv
-                if (train.getLength() > 1) {
-                    nextOccupiedRails.put(train, occupiedRails.get(train));
-                } else {
-                    nextOccupiedRails.put(train, null);
-                }
             } else {
                 train.moveTo(railNetwork, nextPosition);
                 train.setDirection(direction);
-                nextOccupiedRails.put(train, train.getOccupiedRails());
             }
         });
-        checkForBlockCollisions(collisions, occupiedRails, nextOccupiedRails);
+        getStaticCollisions(collisions);
+        collisions.forEach(collision -> collision.forEach(Train::removeFromRails));
         return collisions;
     }
 
@@ -258,10 +257,7 @@ public final class TrainManager {
      */
     private List<Set<Train>> getCollisionsOfOneReverseStep() {
         List<Set<Train>> collisions = new ArrayList<>();
-        Map<Train, Set<Rail>> occupiedRails = trains.values().stream().filter(Train::isPlaced)
-                .collect(Collectors.toMap(Function.identity(), Train::getOccupiedRails));
         // perform step
-        Map<Train, Set<Rail>> nextOccupiedRails = new HashMap<>();
         trains.values().stream().filter(Train::isPlaced).forEach(train -> {
             Vector2D front = train.getFrontPosition();
             Vector2D position = train.getRearPosition();
@@ -269,86 +265,18 @@ public final class TrainManager {
             Vector2D nextPosition = railNetwork.move(position, direction);
             if (nextPosition == null
                     || train.isOnPosition(nextPosition) && !train.getRearPosition().equals(train.getFrontPosition())) {
+                train.moveBackTo(railNetwork, nextPosition);
                 collisions.add(new HashSet<>(Arrays.asList(train)));
-                train.removeFromRails();
-                // see https://ilias.studium.kit.edu/goto.php?target=frm_996924_138875&client_id=produktiv
-                if (train.getLength() > 1) {
-                    nextOccupiedRails.put(train, occupiedRails.get(train));
-                } else {
-                    nextOccupiedRails.put(train, null);
-                }
             } else {
                 train.moveBackTo(railNetwork, nextPosition);
                 train.setDirection(front.subtract(train.getFrontPosition()));
-                nextOccupiedRails.put(train, train.getOccupiedRails());
             }
         });
-        checkForBlockCollisions(collisions, occupiedRails, nextOccupiedRails);
+        getStaticCollisions(collisions);
+        collisions.forEach(collision -> collision.forEach(Train::removeFromRails));
         return collisions;
     }
 
-    /**
-     * Calculate train collisions, removing crashing trains in the process.
-     *
-     * @param collisions list of collisions to expand
-     * @param occupiedRails map of occupied rails before the step
-     * @param nextOccupiedRails map of occupied rails after the step
-     */
-    private void checkForBlockCollisions(List<Set<Train>> collisions, Map<Train, Set<Rail>> occupiedRails,
-                                         Map<Train, Set<Rail>> nextOccupiedRails) {
-        trains.values().stream()
-                // only process placed trains
-                .filter(Train::isPlaced)
-                // if already in a collision, do not process again
-                .filter(train -> collisions.stream().noneMatch(x -> x.contains(train)))
-                .forEach(train -> {
-                    Set<Rail> occupiedByThisTrain = nextOccupiedRails.get(train);
-                    // check each other train
-                    trains.values().stream().filter(x -> x != train).forEach(otherTrain -> {
-                        Set<Rail> occupiedByOtherTrainPreviously = occupiedRails.get(otherTrain);
-                        Set<Rail> occupiedByOtherTrain = nextOccupiedRails.get(otherTrain);
-                        // if train did not occupy any rails (it is not placed, or just derailed with length 1)
-                        if (occupiedByOtherTrain == null) {
-                            // skip
-                            return;
-                        }
-                        // first check if train is on the same rails
-                        boolean anyIntersection = Stream.concat(
-                                occupiedByOtherTrain.stream(), occupiedByOtherTrainPreviously.stream())
-                                // only search in currently occupied rails, previously occupied rails
-                                // will be checked once the other train is processed in the outer loop
-                                .anyMatch(occupiedByThisTrain::contains);
-                        // or simply touches the other train
-                        if (anyIntersection || train.touches(otherTrain)) {
-                            // remove crashing trains
-                            train.removeFromRails();
-                            otherTrain.removeFromRails();
-                            // try to find/merge existing collisions
-                            Set<Train> existingCollision = null;
-                            for (Set<Train> collision : collisions) {
-                                if (collision.contains(otherTrain) || collision.contains(train)) {
-                                    if (existingCollision == null) {
-                                        existingCollision = collision;
-                                        collision.add(train);
-                                        collision.add(otherTrain);
-                                    } else {
-                                        existingCollision.addAll(collision);
-                                        existingCollision.add(train);
-                                        existingCollision.add(otherTrain);
-                                        collisions.remove(collision);
-                                        break;
-                                    }
-                                }
-                            }
-                            if (existingCollision == null) {
-                                // create a new collision
-                                collisions.add(Stream.of(train, otherTrain).collect(Collectors.toSet()));
-                            }
-                        }
-                    });
-                });
-    }
-
     /**
      * Move the trains in this simulation, printing their new positions and any collisions.
      * @param speed amount of steps to move the trains

testcoverage_input.txt

@@ -82,7 +82,7 @@ put train 1 at (0,0) in direction 1,0
 put train 3 at (20,0) in direction -1,0
 put train 2 at (30,0) in direction -1,0
 put train 5 at (15,0) in direction 1,0
-step 1
+step 41
 add switch (40,0) -> (10,10),(40,40)
 add switch (40,0) -> (40,40),(10,10)
 add switch (40,0),(10,0),(0,10)
@@ -92,7 +92,7 @@ create engine really good one pls
 list engines I own
 create coach with water slide
 list coaches with food
-create train-set with electric chair
+create train-set with silent doors
 create train-set W 15 1 true true
 list train-sets in this city
 delete rolling stock your mom

testcoverage_output.txt

@@ -106,7 +106,8 @@ OK
 OK
 OK
 OK
-Crash of train 1,2,3,4,5
+Crash of train 1,3,4,5
+Crash of train 2
 Error, start has to be connected in straight lines to end positions!
 Error, start has to be connected in straight lines to end positions!
 Error, invalid add switch argument syntax