Cleanup and simplification

src/main/java/Main.java

@@ -1,6 +1,5 @@
 import java.io.IOException;
 
-import javax.script.Invocable;
 import javax.script.ScriptEngine;
 import javax.script.ScriptException;
 
@@ -35,7 +34,6 @@ public class Main {
             e.printStackTrace();
         }
 
-        System.exit(0);
         Parser parser = new Parser();
         try (GameLogic logic = new GameLogic(parser)) {
             logic.loadGameState("games/damnCoolTextAdventureFTW.json");

src/main/java/game/logic/GameLogic.java

@@ -6,13 +6,8 @@ import java.util.HashMap;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
-import java.util.function.Predicate;
 
-import game.logic.actionsystem.Action;
 import game.logic.actionsystem.PlayerAction;
-import game.logic.actionsystem.actions.GoDirection;
-import game.logic.actionsystem.actions.Open;
-import game.logic.actionsystem.actions.TakeFrom;
 import game.state.CircularLocationException;
 import game.state.Entity;
 import game.state.EntitySet;
@@ -35,135 +30,136 @@ public class GameLogic implements Closeable {
         // TODO setup code, load from json or so
         ////////////////////////////////////////////////////////////////////////
 
-        // final String NORTH = "north";
+        Entity east = this.state.createEntity("east");
-        // final String SOUTH = "south";
+        Entity west = this.state.createEntity("west");
-        final String EAST = "east";
+        Entity inside = this.state.createEntity("inside");
-        final String WEST = "west";
+        Entity outside = this.state.createEntity("outside");
-        final String INSIDE = "inside";
+        EntitySet genericDirections = EntitySet.createPersistent("genericDirections");
-        final String OUTSIDE = "outside";
+        genericDirections.add(east, west);
+        EntitySet houseDirections = EntitySet.createPersistent("houseDirections");
+        houseDirections.add(inside, outside);
 
         Entity forestPath01 = this.state.createEntity("forest_path_01");
         Entity clearing = this.state.createEntity("clearing");
         Entity houseOutside = this.state.createEntity("house_outside");
         Entity houseInside = this.state.createEntity("house_inside");
         Entity houseMainDoor = this.state.createEntity("house_main_door");
-        houseMainDoor.setClosed(true);
 
-        forestPath01.connectBidirectional(EAST, null, WEST, clearing);
+        EntitySet locations = EntitySet.createPersistent("locations");
-        forestPath01.connectBidirectional(WEST, null, EAST, houseOutside);
+        locations.add(forestPath01, clearing, houseInside, houseOutside);
-        houseOutside.connectBidirectional(INSIDE, houseMainDoor, OUTSIDE, houseInside);
 
-        this.player = this.state.createEntity("player");
+        forestPath01.connectBidirectional(east, west, clearing);
-        Entity apple01 = this.state.createEntity("apple_01", "green");
+        forestPath01.connectBidirectional(west, east, houseOutside);
-        Entity apple02 = this.state.createEntity("apple_02", "red");
+        houseOutside.connectBidirectional(inside, outside, houseInside);
 
-        this.player.setLocation(clearing);
+        this.player = clearing.createContainedEntity(this, "player");
-        apple01.setLocation(forestPath01);
+        Entity apple01 = forestPath01.createContainedEntity(this, "apple_01");
-        apple02.setLocation(forestPath01);
+        Entity apple02 = forestPath01.createContainedEntity(this, "apple_02");
 
-        ////////////////////////////////////////////////////////////////////////
+        EntitySet collectibles = EntitySet.createPersistent("collectibles");
-        // TODO game specific action parsers
+        collectibles.add(apple01, apple02);
-        ////////////////////////////////////////////////////////////////////////
 
-        this.parser.pushActionParser(userInput -> userInput.get(0).equals("go")
+        collectibles.pushPlayerAction("take", (logic, args) -> {
-                ? new GoDirection(userInput.size() < 2 ? null : userInput.get(1))
+            Entity collectible = args[0];
-                : null);
+            if (logic.getPlayer().getLocation() == collectible.getLocation()) {
-        this.parser.pushActionParser(userInput -> {
+                try {
-            if (userInput.get(0).equals("take")) {
+                    collectible.setLocation(logic.getPlayer());
-                int fromIdx = userInput.indexOf("from");
+                    logic.printRaw("Du nimmst %s, du Schuft.\n", collectible);
-                List<EntityDescription> whatToTake = this
+                } catch (CircularLocationException ex) {
-                        .parseDescriptionList(userInput.subList(1, fromIdx == -1 ? userInput.size() : fromIdx));
+                    // Should not happpen
-                List<EntityDescription> whereToTakeFrom = fromIdx == -1 ? null
+                    ex.printStackTrace();
-                        : this.parseDescriptionList(userInput.subList(fromIdx + 1, userInput.size()));
-                return new TakeFrom(whatToTake, whereToTakeFrom);
-            } else {
-                return null;
                 }
-        });
-        this.parser.pushActionParser(userInput -> {
-            if (userInput.get(0).equals("open")) {
-                return new Open(this.parseDescriptionList(userInput.subList(1, userInput.size())));
-            } else {
-                return null;
             }
+            return true;
         });
+
+        // this.player becomes first argument by calling pushPlayerAction on it
+        PlayerAction goAction = this.player.pushPlayerAction("go", (logic, args) -> {
+            Entity character = args[0];
+            Entity direction = args[1];
+            Entity newLocation = character.getLocation().getConnectedEntity(direction);
+            if (newLocation != null) {
+                try {
+                    logic.getPlayer().setLocation(newLocation);
+                    logic.printRaw("Du gehst Richtung %s und landest hier: %s, du Lutscher!\n", direction, newLocation);
+                } catch (CircularLocationException ex) {
+                    ex.printStackTrace();
+                }
+            } else {
+                logic.printRaw("Hier geht es nicht nach %s, du Nichtsnutz.\n", direction);
+            }
+            return true;
+        });
+        // second argument must be exactly 1 of the entites contained in genericDirections
+        goAction.pushVaryingNeededEntites(genericDirections, 1);
+
+        // again first argument becomes this.player by calling pushPlayerAction on it
+        PlayerAction goHouseAction = this.player.pushPlayerAction("go", (logic, args) -> {
+            Entity character = args[0];
+            Entity direction = args[1];
+            Entity newLocation = character.getLocation().getConnectedEntity(direction);
+            if (newLocation != null && character.getLocation() == houseInside
+                    || character.getLocation() == houseOutside) {
+                if (houseMainDoor.getBoolAttribute("open")) {
+                    try {
+                        character.setLocation(newLocation);
+                    } catch (CircularLocationException ex) {
+                        ex.printStackTrace();
+                    }
+                    logic.printRaw("Du gehst durch die Tür, du Eumel.\n");
+                } else {
+                    logic.printRaw("Die Tür ist zu, du Dödel.\n");
+                }
+                return true;
+            }
+            return false;
+        });
+        // second argument must be exactly 1 of the entites contained in houseDirections
+        goHouseAction.pushVaryingNeededEntites(houseDirections, 1);
+
+        houseMainDoor.pushPlayerAction("open", (logic, args) -> {
+            if (logic.getPlayer().getLocation() == houseInside || logic.getPlayer().getLocation() == houseOutside) {
+                if (houseMainDoor.getBoolAttribute("open")) {
+                    logic.printRaw("Die Tür ist schon offen, du Hammel.\n");
+                } else {
+                    houseMainDoor.setAttribute("open", true);
+                    logic.printRaw("Du öffnest die Tür, du Dummbatz.\n");
+                }
+                return true;
+            }
+            return false;
+        });
+
+        houseMainDoor.pushPlayerAction("close", (logic, args) -> {
+            if (logic.getPlayer().getLocation() == houseInside || logic.getPlayer().getLocation() == houseOutside) {
+                if (!houseMainDoor.getBoolAttribute("open")) {
+                    logic.printRaw("Die Tür ist schon geschlossen, du Mummenschanz.\n");
+                } else {
+                    houseMainDoor.setAttribute("open", false);
+                    logic.printRaw("Du schließt die Tür, du Angsthase.\n");
+                }
+                return true;
+            }
+            return false;
+        });
+    }
+
+    public GameState getState() {
+        return this.state;
     }
 
     public Entity getPlayer() {
         return this.player;
     }
 
-    public EntitySet searchForEntity(EntityDescription description) {
-        return this.state.searchForEntity(description);
-    }
-
-    public EntitySet searchForEntity(EntityDescription description, Predicate<Entity> acceptFunction) {
-        return this.state.searchForEntity(description).getFiltered(acceptFunction);
-    }
-
-    public EntitySet searchForNearbyEntity(EntityDescription description) {
-        return this.searchForEntity(description, e -> {
-            if (this.player == null) {
-                return false;
-            } else if (this.player.contains(e, false)) {
-                return true;
-            } else if (this.player.getLocation() != null && this.player.getLocation().contains(e, false)) {
-                return true;
-            } else {
-                for (Entity.EntityConnection c : this.player.getLocation().getConnections().stream()
-                        .map(this.player.getLocation()::getConnection).toList()) {
-                    if (c.associatedEntity() == e) {
-                        return true;
-                    }
-                }
-            }
-            return false;
-        });
-    }
-
     public void mainLoop() {
         while (!this.discontinue) {
-            Action action = this.parser.readAction();
+            this.parser.executeUserInput(this);
-            if (action != null) {
-                action.execute(this);
-            }
         }
     }
 
-    private List<EntityDescription> parseDescriptionList(List<String> words) {
+    public void printRaw(String rawMessage, Object... args) {
-        List<EntityDescription> descriptions = new LinkedList<>();
+        System.out.printf(rawMessage, args);
-        List<String> desc = new LinkedList<>();
-        for (String word : words) {
-            if (word.equals("and")) {
-                descriptions.add(new EntityDescription(desc));
-                desc = new LinkedList<>();
-            } else {
-                desc.add(word);
-            }
-        }
-        if (!desc.isEmpty()) {
-            descriptions.add(new EntityDescription(desc));
-        }
-        return descriptions;
-    }
-
-    public void printToUser(String messageId, Object... args) {
-        System.out.print(messageId);
-        for (int i = 0; i < args.length; ++i) {
-            System.out.print(i == 0 ? " " : ", ");
-            System.out.print(args[i]);
-        }
-        System.out.println();
-    }
-
-    public boolean canPlayerOpen(Entity entity) {
-        // TODO
-        return true;
-    }
-
-    public boolean canPlayerTake(Entity entity) {
-        // TODO
-        return true;
     }
 
     public void registerPlayerAction(PlayerAction action) {

src/main/java/game/logic/Parser.java

@@ -2,33 +2,53 @@ package game.logic;
 
 import java.io.Closeable;
 import java.io.IOException;
+import java.util.ArrayList;
 import java.util.Arrays;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Scanner;
 
-import game.logic.actionsystem.Action;
+import game.state.Entity;
-import game.logic.actionsystem.ActionParser;
+import game.state.EntitySet;
 import startup.Environment;
 import util.Commands;
 import util.TextColors;
 
 public class Parser implements Closeable {
     private final Scanner scanner = new Scanner(System.in);
-    private final List<ActionParser> actionParsers = new LinkedList<>();
 
-    public Action readAction() {
+    public void executeUserInput(GameLogic logic) {
+        // Big TODO
+        // currently just reads an action id followed by entity ids
+
         String greenPrompt = TextColors.BLUE.colorize(">");
         System.out.printf("%s ", greenPrompt);
         List<String> input = Arrays.stream(scanner.nextLine().split("\\s+")).map(String::toLowerCase).toList();
+        if (!input.isEmpty()) {
+            String actionId = input.get(0);
+            List<Entity> args = new ArrayList<>(input.size() - 1);
+            for (int i = 1; i < input.size(); ++i) {
+                Entity e = logic.getState().getEntityById(input.get(i));
+                if (e == null) {
+                    logic.printRaw("Keine Ahnung, was du mit %s meinst, du Tölpel.\n", input.get(i));
+                    return;
+                }
+                args.add(e);
+            }
+            Entity primaryEntity = this.getPrimaryEntity(logic, actionId, args);
+            if (primaryEntity != null) {
+                primaryEntity.tryExecutePlayerAction(actionId, EntitySet.createTemporary(args), logic);
+            } else if(logic.tryExecutePlayerAction(actionId, EntitySet.createTemporary(args))) {
+                logic.printRaw("Das geht doch so nicht.\n", args);
+            }
+        }
+    }
 
-        for (ActionParser actionParser : this.actionParsers) {
+    private Entity getPrimaryEntity(GameLogic logic, String actionId, List<Entity> arguments) {
-            Action action = actionParser.parseAction(input);
+        return switch (actionId) {
-            if (action != null) {
+            case "go" -> logic.getPlayer();
-                return action;
+            case "take", "open", "close" -> arguments.remove(0);
-            }
+            default -> null;
-        }
+        };
-        return null;
     }
 
     public void parse(List<String> parameter) {
@@ -40,10 +60,6 @@ public class Parser implements Closeable {
         }
     }
 
-    public void pushActionParser(ActionParser actionParser) {
-        this.actionParsers.add(actionParser);
-    }
-
     @Override
     public void close() throws IOException {
         this.scanner.close();

src/main/java/game/logic/actionsystem/Action.java

@@ -1,22 +0,0 @@
-package game.logic.actionsystem;
-
-import game.logic.GameLogic;
-
-public abstract class Action {
-    public enum Type {
-        TAKE, DROP,
-        COMBINE_WITH, USE,
-        GIVE_TO, TAKE_FROM,
-        PUT_ON,
-        PUSH, PULL, ROLL, ROLL_TO,
-        TRACE_RAY_TO,
-        KILL, KILL_WITH,
-        SEARCH, SEARCH_FOR,
-        TALK_TO, TELL_TO, ANNOY,
-        LOOK_AT, EXAMINE, READ, WRITE_ON_WITH,
-        HIT, HIT_WITH,
-        GO_TO,
-    }
-
-    public abstract void execute(GameLogic logic);
-}

src/main/java/game/logic/actionsystem/ActionParser.java

@@ -1,7 +0,0 @@
-package game.logic.actionsystem;
-
-import java.util.List;
-
-public interface ActionParser {
-    public Action parseAction(List<String> userInput);
-}

src/main/java/game/logic/actionsystem/PlayerAction.java

@@ -116,7 +116,6 @@ public class PlayerAction {
         if (Arrays.stream(entitiesToUse).anyMatch(Objects::isNull)) {
             return false;
         }
-        this.executor.execute(logic, entitiesToUse);
+        return this.executor.execute(logic, entitiesToUse);
-        return true;
     }
 }

src/main/java/game/logic/actionsystem/PlayerActionExecutor.java

@@ -7,7 +7,7 @@ import game.state.Entity;
  * A player action executor provides specific instructions how to manipulate the
  * game logic.
  */
-public class PlayerActionExecutor {
+public interface PlayerActionExecutor {
 
     /**
      * Executes the game logic manupulation.
@@ -15,7 +15,5 @@ public class PlayerActionExecutor {
      * @param logic The game logic
      * @param args  Arguments
      */
-    public void execute(GameLogic logic, Entity... args) {
+    public boolean execute(GameLogic logic, Entity... args);
-        // TODO
-    }
 }

src/main/java/game/logic/actionsystem/actions/GoDirection.java

@@ -1,44 +0,0 @@
-package game.logic.actionsystem.actions;
-
-import game.logic.GameLogic;
-import game.logic.actionsystem.Action;
-import game.state.CircularLocationException;
-import game.state.Entity;
-
-public class GoDirection extends Action {
-    private final String directionId;
-
-    public GoDirection(String directionId) {
-        this.directionId = directionId;
-    }
-
-    public String getDirectionId() {
-        return this.directionId;
-    }
-
-    @Override
-    public void execute(GameLogic logic) {
-        if (logic.getPlayer() == null) {
-            logic.printToUser("go.player.null");
-        } else {
-            Entity location = logic.getPlayer().getLocation();
-            if (location == null) {
-                logic.printToUser("go.player.location.null", logic.getPlayer());
-            } else {
-                Entity.EntityConnection connection = location.getConnection(this.directionId);
-                if (connection == null || connection.to() == null) {
-                    logic.printToUser("go.direction.unknown", logic.getPlayer().getLocation(), this.directionId);
-                } else if (connection.associatedEntity() != null && connection.associatedEntity().isClosed()) {
-                    logic.printToUser("go.location.closed", connection.associatedEntity());
-                } else {
-                    try {
-                        logic.getPlayer().setLocation(connection.to());
-                        logic.printToUser("go.success", location, connection.to());
-                    } catch (CircularLocationException ex) {
-                        logic.printToUser("go.locationCircular", ex);
-                    }
-                }
-            }
-        }
-    }
-}

src/main/java/game/logic/actionsystem/actions/Open.java

@@ -1,32 +0,0 @@
-package game.logic.actionsystem.actions;
-
-import java.util.List;
-
-import game.logic.EntityDescription;
-import game.logic.GameLogic;
-import game.logic.actionsystem.Action;
-import game.state.Entity;
-import game.state.EntitySet;
-
-public class Open extends Action {
-    private final List<EntityDescription> descriptions;
-
-    public Open(List<EntityDescription> descriptions) {
-        this.descriptions = descriptions;
-    }
-
-    @Override
-    public void execute(GameLogic logic) {
-        for (EntitySet set : this.descriptions.stream().map(logic::searchForNearbyEntity).toList()) {
-            Entity e = set.collapse(logic);
-            if(e == null) {
-                logic.printToUser("open.noEntity");
-            } else if (logic.canPlayerOpen(e)) {
-                e.setClosed(false);
-                logic.printToUser("open.success", e);
-            } else {
-                logic.printToUser("open.failed", e);
-            }
-        }
-    }
-}

src/main/java/game/logic/actionsystem/actions/TakeFrom.java

@@ -1,50 +0,0 @@
-package game.logic.actionsystem.actions;
-
-import java.util.List;
-
-import game.logic.EntityDescription;
-import game.logic.GameLogic;
-import game.logic.actionsystem.Action;
-import game.state.CircularLocationException;
-import game.state.Entity;
-import game.state.EntitySet;
-
-public class TakeFrom extends Action {
-    private final List<EntityDescription> what;
-    private final List<EntityDescription> fromWhere;
-
-    public TakeFrom(List<EntityDescription> what, List<EntityDescription> fromWhere) {
-        this.what = what;
-        this.fromWhere = fromWhere;
-    }
-
-    public List<EntityDescription> getWhat() {
-        return this.what;
-    }
-
-    public List<EntityDescription> getFromWhere() {
-        return this.fromWhere;
-    }
-
-    @Override
-    public void execute(GameLogic logic) {
-        // TODO incorporate fromWhere
-        for (EntityDescription ed : this.what) {
-            EntitySet es = logic.searchForNearbyEntity(ed);
-            if(es.isEmpty()) {
-                logic.printToUser("entity.notFound", ed);
-            }
-            Entity e = es.collapse(logic);
-            if (e != null && logic.canPlayerTake(e)) {
-                try {
-                    e.setLocation(logic.getPlayer());
-                    logic.printToUser("take.success", e);
-                } catch (CircularLocationException ex) {
-                    logic.printToUser("take.error", ex);
-                }
-            } else {
-                logic.printToUser("take.failed", e);
-            }
-        }
-    }
-}

src/main/java/game/state/Entity.java

@@ -1,6 +1,5 @@
 package game.state;
 
-import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
@@ -24,21 +23,16 @@ import game.logic.actionsystem.PlayerActionExecutor;
  * can store generic attributes.
  */
 public class Entity {
-    public record EntityConnection(Entity to, Entity associatedEntity) {
-    }
-
     private final String id;
-    private final Set<String> attributes = new HashSet<>();
-    private Entity location;
-    private boolean closed = false;
-    private final EntitySet contents;
-    private final Map<String, EntityConnection> connections = new HashMap<>();
-    private final Map<String, List<PlayerAction>> playerActions = new HashMap<>();
     final Set<EntitySet> containingPersistentSets = new HashSet<>();
+    private final Map<String, String> attributes = new HashMap<>();
+    private Entity location;
+    private final EntitySet contents;
+    private final Map<Entity, Entity> connections = new HashMap<>();
+    private final Map<String, List<PlayerAction>> playerActions = new HashMap<>();
 
-    public Entity(String id, String... attributes) {
+    public Entity(String id) {
         this.id = id;
-        this.attributes.addAll(Arrays.asList(attributes));
         this.contents = EntitySet.createPersistent(this.id + "::contents");
     }
 
@@ -46,30 +40,25 @@ public class Entity {
         return this.id;
     }
 
-    public Set<String> getAttributes() {
+    public String getAttribute(String key) {
-        return Collections.unmodifiableSet(this.attributes);
+        String value = this.attributes.get(key);
+        return value == null ? "" : value;
     }
 
-    public boolean addAttribute(String attribute) {
+    public boolean getBoolAttribute(String key) {
-        return this.attributes.add(attribute);
+        return Boolean.parseBoolean(this.getAttribute(key));
     }
 
-    public boolean removeAttribute(String attribute) {
+    public void setAttribute(String key, Object value) {
-        return this.attributes.remove(attribute);
+        if (value == null) {
-    }
+            this.attributes.remove(key);
-
+        } else {
-    public void toggleAttribute(String attribute) {
+            this.attributes.put(key, value.toString());
-        if (!this.attributes.remove(attribute)) {
-            this.attributes.add(attribute);
         }
     }
 
-    public void switchAttribute(String attr1, String attr2) {
+    public void removeAttribute(String key) {
-        if (this.attributes.remove(attr1)) {
+        this.setAttribute(key, null);
-            this.attributes.add(attr2);
-        } else if (this.attributes.remove(attr2)) {
-            this.attributes.add(attr1);
-        }
     }
 
     public void setLocation(Entity location) throws CircularLocationException {
@@ -88,18 +77,21 @@ public class Entity {
         }
     }
 
-    public boolean isClosed() {
-        return this.closed;
-    }
-
-    public void setClosed(boolean closed) {
-        this.closed = closed;
-    }
-
     public boolean contains(Entity other, boolean recursive) {
         return this.contents.getAll().stream().anyMatch(e -> e == other || (recursive && e.contains(other, true)));
     }
 
+    public Entity createContainedEntity(GameLogic logic, String id) {
+        Entity e = logic.getState().createEntity(id);
+        try {
+            e.setLocation(this);
+        } catch (CircularLocationException ex) {
+            // should not happen
+            ex.printStackTrace();
+        }
+        return e;
+    }
+
     public Entity getLocation() {
         return this.location;
     }
@@ -108,32 +100,31 @@ public class Entity {
         return this.contents.getAll();
     }
 
-    public void connectUnidirectional(String directionId, Entity to, Entity associatedEntity) {
+    public void connectUnidirectional(Entity direction, Entity to) {
-        this.connections.put(directionId, new EntityConnection(to, associatedEntity));
+        this.connections.put(direction, to);
     }
 
-    public void connectBidirectional(String dirIdFromThisToOther, Entity associatedEntity, String dirIdFromOtherToThis,
+    public void connectBidirectional(Entity dirFromThisToOther, Entity dirFromOtherToThis, Entity other) {
-            Entity to) {
+        this.connections.put(dirFromThisToOther, other);
-        this.connections.put(dirIdFromThisToOther, new EntityConnection(to, associatedEntity));
+        other.connections.put(dirFromOtherToThis, this);
-        to.connections.put(dirIdFromOtherToThis, new EntityConnection(this, associatedEntity));
     }
 
-    public void removeSingleConnection(String directionId) {
+    public void removeSingleConnection(Entity direction) {
-        this.connections.remove(directionId);
+        this.connections.remove(direction);
     }
 
-    public void removeBidirectionalConnection(String dirIdFromThisToOther, String dirIdFromOtherToThis) {
+    public void removeBidirectionalConnection(Entity dirFromThisToOther, Entity dirFromOtherToThis) {
-        EntityConnection c = this.connections.remove(dirIdFromThisToOther);
+        Entity other = this.connections.remove(dirFromThisToOther);
-        if (c != null) {
+        if (other != null && other.connections.get(dirFromOtherToThis) == this) {
-            c.to.connections.remove(dirIdFromOtherToThis);
+            other.connections.remove(dirFromOtherToThis);
         }
     }
 
-    public EntityConnection getConnection(String directionId) {
+    public Entity getConnectedEntity(Entity direction) {
-        return this.connections.get(directionId);
+        return this.connections.get(direction);
     }
 
-    public Set<String> getConnections() {
+    public Set<Entity> getConnectionDirections() {
         return Collections.unmodifiableSet(this.connections.keySet());
     }
 

src/main/java/game/state/EntitySet.java

@@ -33,15 +33,12 @@ public class EntitySet {
     }
 
     private final String name;
-    private final Set<Entity> entities;
+    private final Set<Entity> entities = new HashSet<>();
     private final Map<String, List<PlayerAction>> playerActions = new HashMap<>();
 
     private EntitySet(String name, Collection<Entity> entities) {
         this.name = name;
-        this.entities = new HashSet<>(entities);
+        this.add(entities.toArray(new Entity[0]));
-        if (this.name != null) {
-            this.entities.forEach(e -> e.containingPersistentSets.add(this));
-        }
     }
 
     public boolean isEmpty() {
@@ -56,24 +53,20 @@ public class EntitySet {
         return this.entities.size();
     }
 
-    public boolean add(Entity entity) {
+    public void add(Entity... entities) {
-        if (this.entities.add(entity)) {
+        for (Entity e : entities) {
-            if (this.name != null) {
+            if (this.entities.add(e) && this.name != null) {
-                entity.containingPersistentSets.add(this);
+                e.containingPersistentSets.add(this);
             }
-            return true;
         }
-        return false;
     }
 
-    public boolean remove(Entity entity) {
+    public void remove(Entity... entities) {
-        if(this.entities.remove(entity)) {
+        for (Entity e : entities) {
-            if(this.name != null) {
+            if (this.entities.remove(e) && this.name != null) {
-                entity.containingPersistentSets.remove(this);
+                e.containingPersistentSets.remove(this);
             }
-            return true;
         }
-        return false;
     }
 
     public boolean contains(Entity entity) {

src/main/java/game/state/GameState.java

@@ -1,25 +1,22 @@
 package game.state;
 
-import java.util.LinkedList;
+import java.util.HashMap;
-import java.util.List;
+import java.util.Map;
-
-import game.logic.EntityDescription;
 
 public class GameState {
-    private final List<Entity> entities = new LinkedList<>();
+    private final Map<String, Entity> entities = new HashMap<>();
 
     public GameState() {
 
     }
 
-    public Entity createEntity(String id, String... attributes) {
+    public Entity createEntity(String id) {
-        Entity e = new Entity(id, attributes);
+        Entity e = new Entity(id);
-        this.entities.add(e);
+        this.entities.put(id, e);
         return e;
     }
 
-    public EntitySet searchForEntity(EntityDescription description) {
+    public Entity getEntityById(String id) {
-        return EntitySet.createTemporary(this.entities.stream().filter(e -> e.getId().equals(description.getMainWord())
+        return this.entities.get(id);
-                && e.getAttributes().containsAll(description.getAttributes())).toList());
     }
 }