tracking and tracing

src/main/java/carpet/CarpetServer.java

@@ -11,6 +11,7 @@ import carpet.commands.DistanceCommand;
 import carpet.commands.DrawCommand;
 import carpet.commands.InfoCommand;
 import carpet.commands.LogCommand;
+import carpet.commands.MobAICommand;
 import carpet.commands.PerimeterInfoCommand;
 import carpet.commands.PlayerCommand;
 import carpet.commands.ScriptCommand;
@@ -22,6 +23,7 @@ import carpet.script.CarpetScriptServer;
 import carpet.settings.CarpetSettings;
 import carpet.settings.SettingsManager;
 import carpet.utils.HUDController;
+import carpet.utils.MobAI;
 import com.mojang.brigadier.CommandDispatcher;
 import net.minecraft.server.command.ServerCommandSource;
 import net.minecraft.server.MinecraftServer;
@@ -59,6 +61,7 @@ public class CarpetServer // static for now - easier to handle all around the co
             e.onServerLoaded(server);
         });
         scriptServer = new CarpetScriptServer();
+        MobAI.resetTrackers();
     }
 
     public static void tick(MinecraftServer server)
@@ -88,6 +91,7 @@ public class CarpetServer // static for now - easier to handle all around the co
         PerimeterInfoCommand.register(dispatcher);
         DrawCommand.register(dispatcher);
         ScriptCommand.register(dispatcher);
+        MobAICommand.register(dispatcher);
         extensions.forEach(e -> e.registerCommands(dispatcher));
         //TestCommand.register(dispatcher);
     }

src/main/java/carpet/commands/MobAICommand.java

@@ -0,0 +1,42 @@
+package carpet.commands;
+
+import carpet.settings.CarpetSettings;
+import carpet.utils.MobAI;
+import com.mojang.brigadier.CommandDispatcher;
+import com.mojang.brigadier.arguments.StringArgumentType;
+import com.mojang.brigadier.builder.LiteralArgumentBuilder;
+import net.minecraft.command.arguments.EntitySummonArgumentType;
+import net.minecraft.server.command.ServerCommandSource;
+import net.minecraft.util.registry.Registry;
+
+import static net.minecraft.server.command.CommandManager.argument;
+import static net.minecraft.server.command.CommandManager.literal;
+import static net.minecraft.server.command.CommandSource.suggestMatching;
+
+public class MobAICommand
+{
+    public static void register(CommandDispatcher<ServerCommandSource> dispatcher)
+    {
+        LiteralArgumentBuilder<ServerCommandSource> command = literal("track").
+                requires((player) -> CarpetSettings.commandTrackAI).
+                then(argument("entity type", EntitySummonArgumentType.entitySummon()).
+
+                        suggests( (c, b) -> suggestMatching(MobAI.availbleTypes(), b)).
+                        then(literal("clear").executes( (c) ->
+                                {
+                                    MobAI.clearTracking(Registry.ENTITY_TYPE.get(EntitySummonArgumentType.getEntitySummon(c, "entity type")));
+                                    return 1;
+                                }
+                        )).
+                        then(argument("aspect", StringArgumentType.word()).
+                                suggests( (c, b) -> suggestMatching(MobAI.availableFor(Registry.ENTITY_TYPE.get(EntitySummonArgumentType.getEntitySummon(c, "entity type"))),b)).
+                                executes( (c) -> {
+                                    MobAI.startTracking(
+                                            Registry.ENTITY_TYPE.get(EntitySummonArgumentType.getEntitySummon(c, "entity type")),
+                                            MobAI.TrackingType.byName(StringArgumentType.getString(c, "aspect"))
+                                    );
+                                    return 1;
+                                })));
+        dispatcher.register(command);
+    }
+}

src/main/java/carpet/mixins/VillagerEntity_aiMixin.java

@@ -0,0 +1,80 @@
+package carpet.mixins;
+
+import carpet.utils.Messenger;
+import carpet.utils.MobAI;
+import net.minecraft.entity.EntityType;
+import net.minecraft.entity.ai.brain.Activity;
+import net.minecraft.entity.ai.brain.MemoryModuleType;
+import net.minecraft.entity.passive.AbstractTraderEntity;
+import net.minecraft.entity.passive.VillagerEntity;
+import net.minecraft.particle.ParticleTypes;
+import net.minecraft.server.world.ServerWorld;
+import net.minecraft.util.Timestamp;
+import net.minecraft.world.World;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Shadow;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+
+import java.util.Optional;
+
+@Mixin(VillagerEntity.class)
+public abstract class VillagerEntity_aiMixin extends AbstractTraderEntity
+{
+    @Shadow protected abstract boolean hasSeenGolemRecently(long long_1);
+
+    @Inject(method = "tick", at = @At("HEAD"))
+    private void ontick(CallbackInfo ci)
+    {
+        if (MobAI.isTracking(this, MobAI.TrackingType.IRON_GOLEM_SPAWNING) && !getEntityWorld().isClient())
+        {
+            long time;
+            Optional<Long> optional_1 = this.brain.getOptionalMemory(MemoryModuleType.GOLEM_LAST_SEEN_TIME);
+            if (!optional_1.isPresent()) {
+                time = 0;
+            } else {
+                Long long_2 = optional_1.get();
+                time = long_2+600 - getEntityWorld().getTime();
+            }
+            boolean recentlySeen = hasSeenGolemRecently(getEntityWorld().getTime());
+            Optional<Timestamp> optional_11 = this.brain.getOptionalMemory(MemoryModuleType.LAST_SLEPT);
+            Optional<Timestamp> optional_22 = this.brain.getOptionalMemory(MemoryModuleType.LAST_WORKED_AT_POI);
+            boolean work = false;
+            boolean sleep = false;
+            boolean panic = this.brain.hasActivity(Activity.PANIC);
+            long currentTime = this.world.getTime();
+            if (optional_11.isPresent()) {
+                sleep = (currentTime - optional_11.get().getTime()) < 24000L;
+            }
+            if (optional_22.isPresent()) {
+                work = (currentTime - optional_22.get().getTime()) < 36000L;
+            }
+
+            this.setCustomName(Messenger.c(
+                    (sleep?"eb ":"fb ")+"\u263d ",
+                    (work?"eb ":"fb ")+"\u2692 ",//"\u26CF ",
+                    (panic?"lb ":"fb ")+"\u2623 ",//"\u2622 \u2620 \u26A1 ",
+                    (recentlySeen?"rb ":"lb ")+time ));
+            this.setCustomNameVisible(true);
+        }
+    }
+
+    @Inject(method = "summonGolem", at = @At(
+            value = "INVOKE",
+            target = "Lnet/minecraft/util/math/Box;expand(DDD)Lnet/minecraft/util/math/Box;",
+            shift = At.Shift.AFTER
+    ))
+    private void particleIt(long long_1, int int_1, CallbackInfo ci)
+    {
+        if (MobAI.isTracking(this, MobAI.TrackingType.IRON_GOLEM_SPAWNING) && !getEntityWorld().isClient())
+        {
+            ((ServerWorld) getEntityWorld()).spawnParticles(ParticleTypes.BARRIER, x, y+3, z, 1, 0.1, 0.1, 0.1, 0.0);
+        }
+    }
+
+    public VillagerEntity_aiMixin(EntityType<? extends AbstractTraderEntity> entityType_1, World world_1)
+    {
+        super(entityType_1, world_1);
+    }
+}

src/main/java/carpet/script/CarpetExpression.java

@@ -679,7 +679,6 @@ public class CarpetExpression
         this.expr.addLazyFunction("blast_resistance", -1, (c, t, lv) ->
                 genericStateTest(c, "blast_resistance", lv, (s, p, w) -> new NumericValue(s.getBlock().getBlastResistance())));
 
-        // Deprecated
         this.expr.addLazyFunction("top", -1, (c, t, lv) ->
         {
             String type = lv.get(0).evalValue(c).getString().toLowerCase(Locale.ROOT);
@@ -693,20 +692,10 @@ public class CarpetExpression
                 case "surface": htype = Heightmap.Type.WORLD_SURFACE; break;
                 default: throw new InternalExpressionException("Unknown heightmap type: "+type);
             }
-            int x;
+            BlockValue.LocatorResult locator = BlockValue.fromParams((CarpetContext)c, lv, 1);
-            int z;
+            BlockPos pos = locator.block.getPos();
-            Value v1 = lv.get(1).evalValue(c);
+            int x = pos.getX();
-            if (v1 instanceof BlockValue)
+            int z = pos.getZ();
-            {
-                BlockPos inpos = ((BlockValue)v1).getPos();
-                x = inpos.getX();
-                z = inpos.getZ();
-            }
-            else
-            {
-                x = (int) NumericValue.asNumber(lv.get(1).evalValue(c)).getLong();
-                z = (int) NumericValue.asNumber(lv.get(2).evalValue(c)).getLong();
-            }
             Value retval = new NumericValue(((CarpetContext)c).s.getWorld().getChunk(x >> 4, z >> 4).sampleHeightmap(htype, x & 15, z & 15) + 1);
             return (c_, t_) -> retval;
             //BlockPos pos = new BlockPos(x,y,z);
@@ -965,24 +954,6 @@ public class CarpetExpression
             return (_c, _t) -> res;
         });
 
-        /*this.expr.addLazyFunction("trace_block", -1, (c, t, lv) -> {
-            Value entityValue = lv.get(0).evalValue(c);
-            if (!(entityValue instanceof EntityValue))
-                throw new InternalExpressionException("First argument of trace_block should be an entity");
-            Entity e = ((EntityValue) entityValue).getEntity();
-            HitResult hitres = Tracer.traceEntityLook(e, 20);
-            switch (hitres.getType())
-            {
-                case MISS:
-                    return (_c, _t) -> Value.NULL;
-                case BLOCK:
-                    return (_c, _t) -> new BlockValue(null, e.getEntityWorld(), ((BlockHitResult)hitres).getBlockPos() );
-                case ENTITY:
-                    return (_c, _t) -> new EntityValue(((EntityHitResult)hitres).getEntity());
-            }
-            return LazyValue.NULL;
-        });*/
-
         this.expr.addLazyFunction("set_biome", -1, (c, t, lv) -> {
             CarpetContext cc = (CarpetContext)c;
             BlockValue.LocatorResult locator = BlockValue.fromParams(cc, lv, 0);
@@ -1736,7 +1707,6 @@ public class CarpetExpression
             return (c_, t_) -> ListValue.wrap(retlist);
         });
 
-
         this.expr.addLazyFunction("query", -1, (c, t, lv) -> {
             if (lv.size()<2)
             {
@@ -2516,15 +2486,16 @@ public class CarpetExpression
         this.expr.addLazyFunction("print", 1, (c, t, lv) ->
         {
             ServerCommandSource s = ((CarpetContext)c).s;
+            Value res = lv.get(0).evalValue(c);
             if (s.getEntity() instanceof  PlayerEntity)
             {
-                Messenger.m((PlayerEntity) s.getEntity(), "w "+ lv.get(0).evalValue(c).getString());
+                Messenger.m((PlayerEntity) s.getEntity(), "w "+ res.getString());
             }
             else
             {
-                Messenger.m(s, "w "+ lv.get(0).evalValue(c).getString());
+                Messenger.m(s, "w "+ res.getString());
             }
-            return lv.get(0); // pass through for variables
+            return (_c, _t) -> res; // pass through for variables
         });
 
 

src/main/java/carpet/script/Expression.java

@@ -498,21 +498,9 @@ public class Expression implements Cloneable
                     Value.assertNotNull(v);
                     return lazyfun.apply(c, t, v);
                 }
-                catch (InternalExpressionException exc)
+                catch (RuntimeException exc)
                 {
-                    throw new ExpressionException(e, token, exc.getMessage());
+                    throw handleCodeException(exc, e, token);
-                }
-                catch (ArithmeticException exc)
-                {
-                    throw new ExpressionException(e, token, "Your math is wrong, "+exc.getMessage());
-                }
-                catch (ExitStatement exit)
-                {
-                    throw exit;
-                }
-                catch (Exception exc)
-                {
-                    throw new ExpressionException(e, token, "Error while evaluating expression: "+exc.getMessage());
                 }
             }
         });
@@ -532,21 +520,9 @@ public class Expression implements Cloneable
                     Value.assertNotNull(v1, v2);
                     return lazyfun.apply(c, type, e, t, v1, v2);
                 }
-                catch (InternalExpressionException exc) // might not actually throw it
+                catch (RuntimeException exc)
                 {
-                    throw new ExpressionException(e, t, exc.getMessage());
+                    throw handleCodeException(exc, e, t);
-                }
-                catch (ArithmeticException exc)
-                {
-                    throw new ExpressionException(e, t, "Your math is wrong, "+exc.getMessage());
-                }
-                catch (ExitStatement exit)
-                {
-                    throw exit;
-                }
-                catch (Exception exc)
-                {
-                    throw new ExpressionException(e, t, "Error while evaluating expression: "+exc.getMessage());
                 }
             }
         });
@@ -565,26 +541,27 @@ public class Expression implements Cloneable
                     Value.assertNotNull(v1, v2);
                     return lazyfun.apply(c, t, v1, v2);
                 }
-                catch (InternalExpressionException exc)
+                catch (RuntimeException exc)
                 {
-                    throw new ExpressionException(e, token, exc.getMessage());
+                    throw handleCodeException(exc, e, token);
-                }
-                catch (ArithmeticException exc)
-                {
-                    throw new ExpressionException(e, token, "Your math is wrong, "+exc.getMessage());
-                }
-                catch (ExitStatement exit)
-                {
-                    throw exit;
-                }
-                catch (Exception exc)
-                {
-                    throw new ExpressionException(e, token, "Error while evaluating expression: "+exc.getMessage());
                 }
             }
         });
     }
 
+    private RuntimeException handleCodeException(RuntimeException exc, Expression e, Tokenizer.Token token)
+    {
+        if (exc instanceof ExitStatement)
+            return exc;
+        if (exc instanceof InternalExpressionException)
+            return new ExpressionException(e, token, exc.getMessage());
+        if (exc instanceof ArithmeticException)
+            return new ExpressionException(e, token, "Your math is wrong, "+exc.getMessage());
+        if (exc instanceof ExpressionException)
+            return exc;
+        return new ExpressionException(e, token, "Error while evaluating expression: "+exc.getMessage());
+    }
+
     private void addUnaryOperator(String surface, boolean leftAssoc, Function<Value, Value> fun)
     {
         operators.put(surface+"u", new AbstractUnaryOperator(precedence.get("unary+-!"), leftAssoc)
@@ -679,22 +656,10 @@ public class Expression implements Cloneable
                 {
                     return fun.apply(c, i, lazyParams);
                 }
-                catch (InternalExpressionException exc)
+                catch (RuntimeException exc)
                 {
-                    throw new ExpressionException(e, t, exc.getMessage());
+                    throw handleCodeException(exc, e, t);
                 }
-                catch (ArithmeticException exc)
-                {
-                    throw new ExpressionException(e, t, "Your math is wrong, "+exc.getMessage());
-                }
-                catch (ExitStatement exit)
-                {
-                    throw exit;
-                }
-                //catch (Exception exc)
-                //{
-                //    throw new ExpressionException(e, t, "Error while evaluating expression: "+exc.getMessage());
-                //}
             }
         });
     }
@@ -770,7 +735,7 @@ public class Expression implements Cloneable
                 {
                     throw new ExpressionException(function_context, t, "Your math is wrong, "+exc.getMessage());
                 }
-                catch (ExitStatement exit)
+                catch (ExitStatement | ExpressionException exit)
                 {
                     throw exit;
                 }
@@ -1060,7 +1025,7 @@ public class Expression implements Cloneable
                 Value ret = lv.get(lv.size() - 1).evalValue(c);
                 return (cc, tt) -> ret;
             }
-            return (cc, tt) -> Value.ZERO;
+            return (cc, tt) -> Value.NULL;
         });
     }
 
@@ -1892,8 +1857,6 @@ public class Expression implements Cloneable
             return LazyListValue.range(from, to, step);
         });
 
-        addUnaryFunction("is_list", value -> (value instanceof ListValue)? Value.TRUE : Value.FALSE);
-
         addBinaryFunction("get", (v1, v2) -> v1.getElementAt(v2));
 
         //Deprecated, use "get" instead
@@ -2512,6 +2475,8 @@ public class Expression implements Cloneable
             }
         });
 
+        addUnaryFunction("type", v -> new StringValue(v.getTypeString()));
+
         addUnaryFunction("length", v -> new NumericValue(v.length()));
         addLazyFunction("rand", 1, (c, t, lv) -> {
             Value argument = lv.get(0).evalValue(c);

src/main/java/carpet/script/ScriptHost.java

@@ -73,12 +73,10 @@ public class ScriptHost
         try
         {
             ServerPlayerEntity player = source.getPlayer();
-            CarpetSettings.LOG.error("Retrieving "+player.getName().getString()+" host for "+getName());
             return retrieveForExecution(player.getName().getString());
         }
         catch (CommandSyntaxException e)
         {
-            CarpetSettings.LOG.error("Retrieving global host for "+getName());
             return retrieveForExecution((String)null);
         }
     }

src/main/java/carpet/script/value/BlockValue.java

@@ -241,6 +241,12 @@ public class BlockValue extends Value
         return this != NULL && !getBlockState().isAir();
     }
 
+    @Override
+    public String getTypeString()
+    {
+        return "block";
+    }
+
     @Override
     public Value clone()
     {

src/main/java/carpet/script/value/EntityValue.java

@@ -1,6 +1,7 @@
 package carpet.script.value;
 
 import carpet.fakes.MobEntityInterface;
+import carpet.helpers.Tracer;
 import carpet.script.exception.InternalExpressionException;
 import com.mojang.brigadier.StringReader;
 import com.mojang.brigadier.exceptions.CommandSyntaxException;
@@ -30,6 +31,9 @@ import net.minecraft.server.network.ServerPlayerEntity;
 import net.minecraft.server.world.ServerWorld;
 import net.minecraft.text.LiteralText;
 import net.minecraft.util.Identifier;
+import net.minecraft.util.hit.BlockHitResult;
+import net.minecraft.util.hit.EntityHitResult;
+import net.minecraft.util.hit.HitResult;
 import net.minecraft.util.math.BlockPos;
 import net.minecraft.util.math.Direction;
 import net.minecraft.util.math.Vec3d;
@@ -124,6 +128,12 @@ public class EntityValue extends Value
         return this.get(what, null);
     }
 
+    @Override
+    public String getTypeString()
+    {
+        return "entity";
+    }
+
     public static Pair<EntityType<?>, Predicate<? super Entity>> getPredicate(String who)
     {
         Pair<EntityType<?>, Predicate<? super Entity>> res = entityPredicates.get(who);
@@ -310,20 +320,65 @@ public class EntityValue extends Value
             return new StringValue(Direction.getEntityFacingOrder(e)[index].asString());
         });
 
+        put("trace", (e, a) ->
+        {
+            float reach = 4.5f;
+            boolean entities = true;
+            boolean liquids = false;
+
+            if (a!=null)
+            {
+                if (!(a instanceof ListValue))
+                {
+                    reach = (float) NumericValue.asNumber(a).getDouble();
+                }
+                else
+                {
+                    List<Value> args = ((ListValue) a).getItems();
+                    if (args.size()==0)
+                        throw new InternalExpressionException("trace needs more arguments");
+                    reach = (float) NumericValue.asNumber(args.get(0)).getDouble();
+                    if (args.size() > 1)
+                    {
+                        entities = false;
+                        for (int i = 1; i < args.size(); i++)
+                        {
+                            String what = args.get(i).getString();
+                            if (what.equalsIgnoreCase("entities"))
+                                entities = true;
+                            else if (what.equalsIgnoreCase("blocks")) {}
+                            else if (what.equalsIgnoreCase("liquids"))
+                                liquids = true;
+                            else throw new InternalExpressionException("Incorrect tracing: "+what);
+                        }
+                    }
+                }
+            }
+            else if (e instanceof ServerPlayerEntity && ((ServerPlayerEntity) e).interactionManager.isCreative())
+            {
+                reach = 5.0f;
+            }
+
+            HitResult hitres;
+            if (entities)
+                hitres = Tracer.rayTrace(e, 1, reach, liquids);
+            else
+                hitres = Tracer.rayTraceBlocks(e, 1, reach, liquids);
+
+            switch (hitres.getType())
+            {
+                case MISS: return Value.NULL;
+                case BLOCK: return new BlockValue(null, e.getEntityWorld(), ((BlockHitResult)hitres).getBlockPos() );
+                case ENTITY: return new EntityValue(((EntityHitResult)hitres).getEntity());
+            }
+            return Value.NULL;
+        });
+
         put("nbt",(e, a) -> {
             CompoundTag nbttagcompound = e.toTag((new CompoundTag()));
             if (a==null)
                 return new NBTSerializableValue(nbttagcompound);//StringValue(nbttagcompound.toString());
-            NbtPathArgumentType.NbtPath path;
+            NbtPathArgumentType.NbtPath path = NBTSerializableValue.cachePath(a.getString());
-            try
-            {
-                path = NbtPathArgumentType.nbtPath().method_9362(new StringReader(a.getString()));
-            }
-            catch (CommandSyntaxException exc)
-            {
-                throw new InternalExpressionException("Incorrect path: "+a.getString());
-            }
-            String res = null;
             try
             {
                 List<Tag> tags = path.get(nbttagcompound);
@@ -331,7 +386,7 @@ public class EntityValue extends Value
                     return Value.NULL;
                 if (tags.size()==1)
                     return NBTSerializableValue.decodeTag(tags.get(0));
-                return ListValue.wrap(tags.stream().map(t -> NBTSerializableValue.decodeTag(t)).collect(Collectors.toList()));
+                return ListValue.wrap(tags.stream().map(NBTSerializableValue::decodeTag).collect(Collectors.toList()));
             }
             catch (CommandSyntaxException ignored) { }
             return Value.NULL;
@@ -504,9 +559,13 @@ public class EntityValue extends Value
 
         });
         put("custom_name", (e, v) -> {
-            String name = v.getString();
+            if (v instanceof NullValue)
-            if (name.isEmpty())
+            {
+                e.setCustomNameVisible(false);
                 e.setCustomName(null);
+                return;
+            }
+            e.setCustomNameVisible(true);
             e.setCustomName(new LiteralText(v.getString()));
         });
         put("dismount", (e, v) -> e.stopRiding() );

src/main/java/carpet/script/value/FunctionSignatureValue.java

@@ -1,7 +1,7 @@
 package carpet.script.value;
 
 import carpet.script.exception.ExpressionException;
-import carpet.script.value.Value;
+import carpet.script.exception.InternalExpressionException;
 
 import java.util.List;
 
@@ -23,6 +23,12 @@ public class FunctionSignatureValue extends Value
         throw new ExpressionException("Function "+identifier+" is not defined yet");
     }
 
+    @Override
+    public String getTypeString()
+    {
+        throw new InternalExpressionException("How did you get here? Cannot get type of an internal struct.");
+    }
+
     @Override
     public Value clone()
     {

src/main/java/carpet/script/value/GlobalValue.java

@@ -1,6 +1,6 @@
 package carpet.script.value;
 
-import carpet.script.value.Value;
+import carpet.script.exception.InternalExpressionException;
 
 public class GlobalValue extends Value
 {
@@ -21,4 +21,10 @@ public class GlobalValue extends Value
     {
         return false;
     }
+
+    @Override
+    public String getTypeString()
+    {
+        throw new InternalExpressionException("How did you get here? Cannot get type of an internal struct.");
+    }
 }

src/main/java/carpet/script/value/LazyListValue.java

@@ -111,5 +111,10 @@ public abstract class LazyListValue extends ListValue implements Iterator<Value>
     {
         throw new InternalExpressionException("get element can only be obtained for regular lists");
     }
+    @Override
+    public String getTypeString()
+    {
+        return "iterator";
+    }
 
 }

src/main/java/carpet/script/value/ListValue.java

@@ -326,6 +326,11 @@ public class ListValue extends Value
         index = index % numitems;
         return items.get((int)index);
     }
+    @Override
+    public String getTypeString()
+    {
+        return "list";
+    }
 
 
 

src/main/java/carpet/script/value/NBTSerializableValue.java

@@ -26,8 +26,6 @@ import java.util.Map;
 import java.util.function.Supplier;
 import java.util.stream.Collectors;
 
-import static java.lang.Math.abs;
-
 public class NBTSerializableValue extends Value
 {
     private String nbtString = null;
@@ -224,31 +222,38 @@ public class NBTSerializableValue extends Value
         }
     }
 
-    @Override
+    private static Map<String, NbtPathArgumentType.NbtPath> pathCache = new HashMap<>();
-    public Value getElementAt(Value value)
+    public static NbtPathArgumentType.NbtPath cachePath(String arg)
     {
-        String pathString = value.getString();
+        NbtPathArgumentType.NbtPath res = pathCache.get(arg);
-
+        if (res != null)
-        //return Value.NULL;
+            return res;
-
-        NbtPathArgumentType.NbtPath path;
         try
         {
-            path = NbtPathArgumentType.nbtPath().method_9362(new StringReader(pathString));
+            res = NbtPathArgumentType.nbtPath().method_9362(new StringReader(arg));
         }
         catch (CommandSyntaxException exc)
         {
-            throw new InternalExpressionException("Incorrect nbt path: "+pathString);
+            throw new InternalExpressionException("Incorrect nbt path: "+arg);
         }
-        String res = null;
+        if (pathCache.size() > 1024)
+            pathCache.clear();
+        pathCache.put(arg, res);
+        return res;
+    }
+
+    @Override
+    public Value getElementAt(Value value)
+    {
+        NbtPathArgumentType.NbtPath path = cachePath(value.getString());
         try
         {
             List<Tag> tags = path.get(getTag());
             if (tags.size()==0)
                 return Value.NULL;
             if (tags.size()==1)
-                return new NBTSerializableValue(tags.get(0));
+                return NBTSerializableValue.decodeTag(tags.get(0));
-            return ListValue.wrap(tags.stream().map(NBTSerializableValue::new).collect(Collectors.toList()));
+            return ListValue.wrap(tags.stream().map(NBTSerializableValue::decodeTag).collect(Collectors.toList()));
         }
         catch (CommandSyntaxException ignored) { }
         return Value.NULL;
@@ -259,4 +264,10 @@ public class NBTSerializableValue extends Value
         index = index % numitems;
         return items.get((int)index); */
     }
+
+    @Override
+    public String getTypeString()
+    {
+        return "nbt";
+    }
 }

src/main/java/carpet/script/value/NullValue.java

@@ -38,4 +38,10 @@ public class NullValue extends NumericValue // TODO check nonsingleton code
     {
         return  o instanceof NullValue ? 0 : -1;
     }
+
+    @Override
+    public String getTypeString()
+    {
+        return "null";
+    }
 }

src/main/java/carpet/script/value/NumericValue.java

@@ -167,4 +167,10 @@ public class NumericValue extends Value
         return getLong();
     }
 
+    @Override
+    public String getTypeString()
+    {
+        return "number";
+    }
+
 }

src/main/java/carpet/script/value/StringValue.java

@@ -24,4 +24,10 @@ public class StringValue extends Value
     {
         this.str = str;
     }
+
+    @Override
+    public String getTypeString()
+    {
+        return "number";
+    }
 }

src/main/java/carpet/script/value/Value.java

@@ -177,4 +177,6 @@ public abstract class Value implements Comparable<Value>, Cloneable
     {
         throw new InternalExpressionException("get element can only be obtained for lists and nbt values");
     }
+
+    public abstract String getTypeString();
 }

src/main/java/carpet/settings/CarpetSettings.java

@@ -211,6 +211,9 @@ public class CarpetSettings
     @Rule(desc = "Enables /player command to control/spawn players", category = COMMAND)
     public static boolean commandPlayer = true;
 
+    @Rule(desc = "Allows to track mobs AI via /track command", category = COMMAND)
+    public static boolean commandTrackAI = true;
+
     @Rule(desc = "Placing carpets may issue carpet commands for non-op players", category = SURVIVAL)
     public static boolean carpets = false;
 

src/main/java/carpet/utils/MobAI.java

@@ -0,0 +1,93 @@
+package carpet.utils;
+
+import carpet.CarpetServer;
+import com.google.common.collect.Sets;
+import net.minecraft.entity.Entity;
+import net.minecraft.entity.EntityType;
+import net.minecraft.server.world.ServerWorld;
+import net.minecraft.util.registry.Registry;
+
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+public class MobAI
+{
+    private static Map<EntityType,Set<TrackingType>> aiTrackers = new HashMap<>();
+
+    public static void resetTrackers()
+    {
+        aiTrackers.clear();
+    }
+
+    public static boolean isTracking(Entity e, TrackingType type)
+    {
+        Set<TrackingType> currentTrackers = aiTrackers.get(e.getType());
+        if (currentTrackers == null)
+            return false;
+        return currentTrackers.contains(type);
+    }
+
+    public static void clearTracking(EntityType etype)
+    {
+        aiTrackers.remove(etype);
+        for(ServerWorld world : CarpetServer.minecraft_server.getWorlds() )
+        {
+            for (Entity e: world.getEntities(etype, Entity::hasCustomName))
+            {
+                e.setCustomNameVisible(false);
+                e.setCustomName(null);
+            }
+        }
+    }
+
+    public static void startTracking(EntityType e, TrackingType type)
+    {
+        aiTrackers.putIfAbsent(e,Sets.newHashSet());
+        aiTrackers.get(e).add(type);
+    }
+
+    public static List<String> availbleTypes()
+    {
+        Set<EntityType> types = new HashSet<>();
+        for (TrackingType type: TrackingType.values())
+        {
+            types.addAll(type.types);
+        }
+        return types.stream().map(t -> Registry.ENTITY_TYPE.getId(t).getPath()).collect(Collectors.toList());
+    }
+
+    public static List<String> availableFor(EntityType<?> entityType)
+    {
+        Set<TrackingType> availableOptions = new HashSet<>();
+        for (TrackingType type: TrackingType.values())
+            for (EntityType etype: type.types)
+                if (etype == entityType)
+                    availableOptions.add(type);
+        return availableOptions.stream().map(t -> t.name).collect(Collectors.toList());
+    }
+
+    public enum TrackingType
+    {
+        IRON_GOLEM_SPAWNING("iron_golem_spawning", Sets.newHashSet(EntityType.VILLAGER));
+        public Set<EntityType> types;
+        public String name;
+        TrackingType(String name, Set<EntityType> applicableTypes)
+        {
+            this.name = name;
+            types = applicableTypes;
+        }
+
+        public static TrackingType byName(String aspect)
+        {
+            for (TrackingType type: values())
+                if (type.name.equalsIgnoreCase(aspect))
+                    return type;
+            return null;
+        }
+    }
+
+}

src/main/resources/carpet.mixins.json

@@ -27,6 +27,8 @@
     "ServerWorld_unloadedEntityMixin",
     "MobEntity_leashMixin",
 
+    "VillagerEntity_aiMixin",
+
     "ServerWorld_fakePlayersMixin",
 
     "ServerPlayNetworkHandler_coreMixin",