Fix WrappedList - NBT lists may now be heterogeneous (#3394)

Author: Brokkonaut

src/main/java/com/comphenix/protocol/wrappers/nbt/NbtList.java

@@ -23,7 +23,7 @@ public interface NbtList<TType> extends NbtBase<List<NbtBase<TType>>>, Iterable<
     String EMPTY_NAME = "";
 
     /**
-     * Get the type of each element.
+     * Get the type of each element. For heterogeneous lists this will return {@link NbtType#TAG_COMPOUND TAG_COMPOUND}.
      * <p>
      * This will be {@link NbtType#TAG_END TAG_END} if the NBT list has just been created.
      * @return Element type.
@@ -32,18 +32,32 @@ public interface NbtList<TType> extends NbtBase<List<NbtBase<TType>>>, Iterable<
 
     /**
      * Set the type of each element.
+     * <p>
+     * In 1.21.5 and up lists can be heterogeneous, here the type is only used to convert elements added with {@link NbtList#addClosest(Object)}
      * @param type - type of each element.
+     * @deprecated since 1.21.5 lists can be heterogeneous
      */
+    @Deprecated
     void setElementType(NbtType type);
 
     /**
      * Add a value to a typed list by attempting to convert it to the nearest value.
      * <p>
      * Note that the list must be typed by setting {@link #setElementType(NbtType)} before calling this function.
      * @param value - the value to add.
+     * @deprecated since 1.21.5 lists can be heterogeneous. Use {@link NbtList#addClosest(Object, NbtType)}
      */
+    @Deprecated
     void addClosest(Object value);
-    
+
+    /**
+     * Add a value to a typed list by attempting to convert it to the nearest value.
+     * <p>
+     * @param value - the value to add.
+     * @param type - the resulting type of the entry
+     */
+    void addClosest(Object value, NbtType type);
+
     /**
      * Add a NBT list or NBT compound to the list.
      * @param element Element to add

src/main/java/com/comphenix/protocol/wrappers/nbt/WrappedList.java

@@ -17,6 +17,7 @@
 
 package com.comphenix.protocol.wrappers.nbt;
 
+import com.comphenix.protocol.utility.MinecraftVersion;
 import com.comphenix.protocol.wrappers.collection.ConvertedList;
 import com.comphenix.protocol.wrappers.nbt.io.NbtBinarySerializer;
 import com.google.common.base.Joiner;
@@ -103,7 +104,9 @@ public static <T> NbtList<T> fromList(String name, Collection<? extends T> eleme
      */
     public WrappedList(Object handle) {
         this.container = new WrappedElement<>(handle);
-        this.elementType = container.getSubType();
+        if (!MinecraftVersion.v1_21_5.atOrAbove()) {
+            this.elementType = container.getSubType();
+        }
     }
 
     /**
@@ -113,7 +116,9 @@ public WrappedList(Object handle) {
      */
     public WrappedList(Object handle, String name) {
         this.container = new WrappedElement<>(handle, name);
-        this.elementType = container.getSubType();
+        if (!MinecraftVersion.v1_21_5.atOrAbove()) {
+            this.elementType = container.getSubType();
+        }
     }
 
     @Override
@@ -141,13 +146,28 @@ public NbtType getType() {
 
     @Override
     public NbtType getElementType() {
-        return elementType;
+        if (!MinecraftVersion.v1_21_5.atOrAbove()) {
+            return elementType;
+        } else {
+            List<NbtBase<TType>> value = getValue();
+            NbtType type = NbtType.TAG_END;
+            for (NbtBase<TType> entry : value) {
+                if (type == NbtType.TAG_END) {
+                    type = entry.getType();
+                } else if (type != entry.getType()) {
+                    return NbtType.TAG_COMPOUND;
+                }
+            }
+            return type;
+        }
     }
 
     @Override
     public void setElementType(NbtType type) {
         this.elementType = type;
-        container.setSubType(type);
+        if (!MinecraftVersion.v1_21_5.atOrAbove()) {
+            container.setSubType(type);
+        }
     }
 
     @Override
@@ -171,14 +191,16 @@ private void verifyElement(NbtBase<TType> element) {
                     if (!element.getName().equals(EMPTY_NAME))
                         throw new IllegalArgumentException("Cannot add a the named NBT tag " + element + " to a list.");
 
-                    // Check element type
-                    if (getElementType() != NbtType.TAG_END) {
-                        if (!element.getType().equals(getElementType())) {
-                            throw new IllegalArgumentException(
-                                    "Cannot add " + element + " of " + element.getType() + " to a list of type " + getElementType());
+                    if (!MinecraftVersion.v1_21_5.atOrAbove()) {
+                        // Check element type
+                        if (getElementType() != NbtType.TAG_END) {
+                            if (!element.getType().equals(getElementType())) {
+                                throw new IllegalArgumentException(
+                                        "Cannot add " + element + " of " + element.getType() + " to a list of type " + getElementType());
+                            }
+                        } else {
+                            container.setSubType(element.getType());
                         }
-                    } else {
-                        container.setSubType(element.getType());
                     }
                 }
 
@@ -235,16 +257,21 @@ public NbtBase<List<NbtBase<TType>>> deepClone() {
     }
 
     @Override
-    @SuppressWarnings("unchecked")
     public void addClosest(Object value) {
-        if (getElementType() == NbtType.TAG_END)
+        if (elementType == NbtType.TAG_END)
             throw new IllegalStateException("This list has not been typed yet.");
-        
+
+        addClosest(value, elementType);
+    }
+
+    @Override
+    @SuppressWarnings("unchecked")
+    public void addClosest(Object value, NbtType type) {
         if (value instanceof Number) {
             Number number = (Number) value;
 
             // Convert the number
-            switch (getElementType()) {
+            switch (type) {
                 case TAG_BYTE: add(number.byteValue()); break;
                 case TAG_SHORT: add(number.shortValue()); break;
                 case TAG_INT: add(number.intValue()); break;
@@ -262,7 +289,7 @@ public void addClosest(Object value) {
 
         } else {
             // Just add it
-            add((NbtBase<TType>) NbtFactory.ofWrapper(getElementType(), EMPTY_NAME, value));
+            add((NbtBase<TType>) NbtFactory.ofWrapper(type, EMPTY_NAME, value));
         }
     }
 
@@ -355,7 +382,7 @@ public void setValue(List<NbtBase<TType>> newValue) {
         }
 
         // Update the sub type as well
-        if (lastElement != null) {
+        if (lastElement != null && !MinecraftVersion.v1_21_5.atOrAbove()) {
             container.setSubType(lastElement.getType());
         }
     }

src/main/java/com/comphenix/protocol/wrappers/nbt/io/NbtConfigurationSerializer.java

@@ -261,10 +261,9 @@ private NbtWrapper<?> readNode(ConfigurationSection parent, String name) {
 
             if (node instanceof List) {
                 NbtList<Object> list = NbtFactory.ofList(decoded[0]);
-                list.setElementType(type);
 
                 for (Object value : (List<Object>) node) {
-                    list.addClosest(toNodeValue(value, type));
+                    list.addClosest(toNodeValue(value, type), type);
                 }
 
                 // Add the list

src/test/java/com/comphenix/protocol/wrappers/nbt/io/NbtConfigurationSerializerTest.java

@@ -24,6 +24,7 @@ public void testSerialization() {
         compound.put("name", "test");
         compound.put("values", new int[]{1, 2, 3});
         compound.put(NbtFactory.ofList("telephone", "12345678", "81549300"));
+        compound.put(NbtFactory.ofList("heterogeneous", "somestring", 12345, 1.0));
 
         compound.put(NbtFactory.ofList("lists", NbtFactory.ofList("", "a", "a", "b", "c")));