More routing refactoring

src/api/java/mods/railcraft/api/track/SwitchActuator.java

@@ -1,18 +1,16 @@
 package mods.railcraft.api.track;
 
-import org.jetbrains.annotations.Nullable;
 import net.minecraft.world.entity.vehicle.AbstractMinecart;
 
 public interface SwitchActuator {
+
   /**
-   * This method is used by the switch track to ask the actuator
-   * device whether it thinks the track should be switched or not. Ultimately,
-   * the track itself will decide whether it will be switched, however the
-   * track will usually try to honor results of this method when possible.
+   * This method is used by the switch track to ask the actuator device whether it thinks the track
+   * should be switched or not. Ultimately, the track itself will decide whether it will be
+   * switched, however the track will usually try to honour results of this method when possible.
    *
-   * @param cart        The cart that the switch may use to determine switch status.
-   *                    Implementations should expect null values.
+   * @param cart - the cart that the switch may use to determine switch status
    * @return true if the actuator would like the track switched
    */
-  boolean shouldSwitch(@Nullable AbstractMinecart cart);
+  boolean shouldSwitch(AbstractMinecart cart);
 }

src/main/java/mods/railcraft/client/gui/screen/inventory/SwitchTrackRouterScreen.java

@@ -8,7 +8,6 @@
 import mods.railcraft.client.gui.widget.button.MultiButton;
 import mods.railcraft.network.NetworkChannel;
 import mods.railcraft.network.play.SetSwitchTrackRouterAttributesMessage;
-import mods.railcraft.util.routing.RoutingLogic;
 import mods.railcraft.util.routing.RoutingLogicException;
 import mods.railcraft.world.inventory.SwitchTrackRouterMenu;
 import mods.railcraft.world.level.block.entity.SwitchTrackRouterBlockEntity;
@@ -42,16 +41,15 @@ public SwitchTrackRouterScreen(SwitchTrackRouterMenu menu, Inventory inventory,
     this.registerWidgetRenderer(new WidgetRenderer<>(menu.getErrorWidget()) {
       @Override
       public List<Component> getTooltip() {
-        return menu.getLogic()
-            .map(RoutingLogic::getError)
-            .map(RoutingLogicException::getToolTip)
+        return menu.getSwitchTrackRouter().logicError()
+            .map(RoutingLogicException::getTooltip)
             .orElse(null);
       }
 
       @Override
       public void render(ResourceLocation widgetLocation, GuiGraphics guiGraphics, int centreX,
           int centreY, int mouseX, int mouseY) {
-        if (getTooltip() != null) {
+        if (this.getTooltip() != null) {
           super.render(widgetLocation, guiGraphics, centreX, centreY, mouseX, mouseY);
         }
       }

src/main/java/mods/railcraft/util/routing/Router.java

@@ -0,0 +1,21 @@
+package mods.railcraft.util.routing;
+
+
+import java.util.Optional;
+import com.mojang.datafixers.util.Either;
+
+public interface Router {
+
+  void resetLogic();
+
+  Optional<Either<RoutingLogic, RoutingLogicException>> logicResult();
+
+  default Optional<RoutingLogic> logic() {
+    return this.logicResult().flatMap(Either::left);
+  }
+
+  default Optional<RoutingLogicException> logicError() {
+    return this.logicResult().flatMap(Either::right);
+  }
+}
+

src/main/java/mods/railcraft/util/routing/RoutingLogic.java

@@ -4,7 +4,6 @@
 import java.util.ArrayDeque;
 import java.util.Deque;
 import java.util.NoSuchElementException;
-import org.jetbrains.annotations.Nullable;
 import mods.railcraft.Translations;
 import mods.railcraft.api.carts.NeedsFuel;
 import mods.railcraft.api.carts.Paintable;
@@ -22,39 +21,11 @@
 import mods.railcraft.util.routing.expression.condition.TypeCondition;
 import net.minecraft.world.entity.vehicle.AbstractMinecart;
 
-public class RoutingLogic {
+public record RoutingLogic(Deque<Expression> expressions) {
 
   public static final String REGEX_SYMBOL = "\\?";
 
-  private Deque<Expression> expressions;
-  private RoutingLogicException error;
-
-  private RoutingLogic(@Nullable Deque<String> data) {
-    try {
-      if (data != null) {
-        this.parseTable(data);
-      } else {
-        throw new RoutingLogicException(Translations.RoutingTable.ERROR_BLANK);
-      }
-    } catch (RoutingLogicException ex) {
-      this.error = ex;
-    }
-  }
-
-  public static RoutingLogic buildLogic(@Nullable Deque<String> data) {
-    return new RoutingLogic(data);
-  }
-
-  @Nullable
-  public RoutingLogicException getError() {
-    return this.error;
-  }
-
-  public boolean isValid() {
-    return this.expressions != null;
-  }
-
-  private void parseTable(Deque<String> data) throws RoutingLogicException {
+  public static RoutingLogic parseTable(Deque<String> data) throws RoutingLogicException {
     Deque<Expression> stack = new ArrayDeque<>();
     var it = data.descendingIterator();
     while (it.hasNext()) {
@@ -64,7 +35,7 @@ private void parseTable(Deque<String> data) throws RoutingLogicException {
       }
       stack.push(parseLine(line, stack));
     }
-    expressions = stack;
+    return new RoutingLogic(stack);
   }
 
   private static AbstractMinecart getRoutableCart(AbstractMinecart cart) {

src/main/java/mods/railcraft/util/routing/RoutingLogicException.java

@@ -6,19 +6,21 @@
 
 public class RoutingLogicException extends Exception {
 
+  private static final long serialVersionUID = -8668211003307380722L;
+
   private final List<Component> tooltip;
 
   public RoutingLogicException(String errorKey) {
-    tooltip = List.of(Component.translatable(errorKey).withStyle(ChatFormatting.RED));
+    this.tooltip = List.of(Component.translatable(errorKey).withStyle(ChatFormatting.RED));
   }
 
   public RoutingLogicException(String errorKey, String line) {
     var error = Component.translatable(errorKey).withStyle(ChatFormatting.RED);
     var lineLiteral = Component.literal("\"" + line + "\"");
-    tooltip = List.of(error, lineLiteral);
+    this.tooltip = List.of(error, lineLiteral);
   }
 
-  public List<Component> getToolTip() {
+  public List<Component> getTooltip() {
     return this.tooltip;
   }
 }

src/main/java/mods/railcraft/world/inventory/SwitchTrackRouterMenu.java

@@ -1,8 +1,6 @@
 package mods.railcraft.world.inventory;
 
-import java.util.Optional;
 import mods.railcraft.gui.widget.Widget;
-import mods.railcraft.util.routing.RoutingLogic;
 import mods.railcraft.world.item.RoutingTableBookItem;
 import mods.railcraft.world.level.block.entity.SwitchTrackRouterBlockEntity;
 import net.minecraft.world.entity.player.Inventory;
@@ -17,7 +15,8 @@ public class SwitchTrackRouterMenu extends RailcraftMenu {
 
   public SwitchTrackRouterMenu(int id, Inventory inventory,
       SwitchTrackRouterBlockEntity blockEntity) {
-    super(RailcraftMenuTypes.SWITCH_TRACK_ROUTER.get(), id, inventory.player, blockEntity::isStillValid);
+    super(RailcraftMenuTypes.SWITCH_TRACK_ROUTER.get(), id, inventory.player,
+        blockEntity::isStillValid);
     this.switchTrackRouter = blockEntity;
 
     var routingTableBookSlot = new Slot(switchTrackRouter, 0, 35, 24) {
@@ -43,7 +42,7 @@ public boolean allowModification(Player player) {
       public void setChanged() {
         super.setChanged();
         switchTrackRouter.resetLogic();
-        switchTrackRouter.getLogic().ifPresent(logic -> error.hidden = logic.getError() == null);
+        error.hidden = switchTrackRouter.logicError().isEmpty();
       }
     };
 
@@ -59,8 +58,4 @@ public SwitchTrackRouterBlockEntity getSwitchTrackRouter() {
   public Widget getErrorWidget() {
     return this.error;
   }
-
-  public Optional<RoutingLogic> getLogic() {
-    return this.switchTrackRouter.getLogic();
-  }
 }

src/main/java/mods/railcraft/world/level/block/entity/SwitchTrackRouterBlockEntity.java

@@ -9,6 +9,7 @@
 import java.util.stream.Collectors;
 import org.jetbrains.annotations.Nullable;
 import com.mojang.authlib.GameProfile;
+import com.mojang.datafixers.util.Either;
 import mods.railcraft.Translations;
 import mods.railcraft.api.track.SwitchActuator;
 import mods.railcraft.api.util.EnumUtil;
@@ -19,8 +20,9 @@
 import mods.railcraft.util.container.AdvancedContainer;
 import mods.railcraft.util.container.ForwardingContainer;
 import mods.railcraft.util.routing.RouterBlockEntity;
-import mods.railcraft.util.routing.RouterLogic;
+import mods.railcraft.util.routing.Router;
 import mods.railcraft.util.routing.RoutingLogic;
+import mods.railcraft.util.routing.RoutingLogicException;
 import mods.railcraft.world.entity.vehicle.CartTools;
 import mods.railcraft.world.inventory.SwitchTrackRouterMenu;
 import mods.railcraft.world.level.block.track.actuator.SwitchTrackActuatorBlock;
@@ -39,11 +41,11 @@
 import net.minecraft.world.level.block.state.BlockState;
 
 public class SwitchTrackRouterBlockEntity extends LockableSwitchTrackActuatorBlockEntity
-    implements ForwardingContainer, MenuProvider, RouterBlockEntity, RouterLogic, SwitchActuator {
+    implements ForwardingContainer, MenuProvider, RouterBlockEntity, Router, SwitchActuator {
 
   private final AdvancedContainer container;
   @Nullable
-  private RoutingLogic logic;
+  private Either<RoutingLogic, RoutingLogicException> logic;
   private Railway railway = Railway.PUBLIC;
   private boolean powered;
 
@@ -109,32 +111,36 @@ public boolean isPowered() {
   }
 
   @Override
-  public Optional<RoutingLogic> getLogic() {
-    refreshLogic();
-    return Optional.ofNullable(logic);
+  public Optional<Either<RoutingLogic, RoutingLogicException>> logicResult() {
+    this.refreshLogic();
+    return Optional.ofNullable(this.logic);
   }
 
   @Override
   public void resetLogic() {
-    logic = null;
+    this.logic = null;
   }
 
   private void refreshLogic() {
-    if (logic == null && !container.getItem(0).isEmpty()) {
-      var item = container.getItem(0);
+    if (this.logic == null && !this.container.getItem(0).isEmpty()) {
+      var item = this.container.getItem(0);
       if (item.getTag() != null && item.getTag().contains("pages")) {
         var content = loadPages(item.getTag());
-        logic = RoutingLogic.buildLogic(content);
+        try {
+          this.logic = Either.left(RoutingLogic.parseTable(content));
+        } catch (RoutingLogicException e) {
+          this.logic = Either.right(e);
+        }
       }
     }
   }
 
   @Override
-  public boolean shouldSwitch(@Nullable AbstractMinecart cart) {
-    boolean shouldSwitch = getLogic()
-        .map(l -> cart != null && l.isValid() && l.matches(this, cart))
+  public boolean shouldSwitch(AbstractMinecart cart) {
+    var shouldSwitch = this.logic()
+        .map(logic -> logic.matches(this, cart))
         .orElse(false);
-    if (cart != null && railway.equals(Railway.PRIVATE)) {
+    if (this.railway == Railway.PRIVATE) {
       var cartOwner = CartTools.getCartOwner(cart);
       if (cartOwner == null) {
         shouldSwitch = false;
@@ -150,7 +156,7 @@ public boolean shouldSwitch(@Nullable AbstractMinecart cart) {
   private static Deque<String> loadPages(CompoundTag tag) {
     Deque<String> contents = new LinkedList<>();
     var pages = tag.getList("pages", Tag.TAG_STRING).copy();
-    for(int i = 0; i < pages.size(); i++) {
+    for (int i = 0; i < pages.size(); i++) {
       var page = pages.getString(i).split("\n");
       contents.addAll(Arrays.asList(page));
     }

src/main/java/mods/railcraft/world/level/block/entity/track/SwitchTrackBlockEntity.java

@@ -170,21 +170,20 @@ public final BlockPos getActuatorBlockPos() {
    * whether the switch is sprung or not. It caches the server responses for the clients to use.
    * Note: This method should not modify any variables except the cache, we leave that to update().
    */
-  public boolean shouldSwitchForCart(@Nullable AbstractMinecart cart) {
-    if (cart == null || this.level.isClientSide())
-      return false;
-
-    if (this.springingCarts.contains(cart.getUUID()))
+  public boolean shouldSwitchForCart(AbstractMinecart cart) {
+    if (this.springingCarts.contains(cart.getUUID())) {
       return true; // Carts at the spring entrance always are on switched tracks
+    }
 
-    if (this.lockingCarts.contains(cart.getUUID()))
+    if (this.lockingCarts.contains(cart.getUUID())) {
       return false; // Carts at the locking entrance always are on locked tracks
+    }
 
-    var sameTrain = this.currentCart() != null && RollingStock.getOrThrow(cart)
-        .isSameTrainAs(this.currentCart());
+    var sameTrain = this.currentCart() != null
+        && RollingStock.getOrThrow(cart).isSameTrainAs(this.currentCart());
 
     boolean shouldSwitch = false;
-    var actuatorBlockEntity =  this.level.getBlockEntity(this.getActuatorBlockPos());
+    var actuatorBlockEntity = this.level.getBlockEntity(this.getActuatorBlockPos());
     if (actuatorBlockEntity instanceof SwitchActuator switchActuator) {
       shouldSwitch = switchActuator.shouldSwitch(cart);
     }