Rework field-naming api to be more sensible

src/main/java/de/bluecolored/bluenbt/BlueNBT.java

@@ -44,13 +44,7 @@ public class BlueNBT {
     private final Map<TypeToken<?>, InstanceCreator<?>> instanceCreatorMap = new HashMap<>();
 
     @Getter @Setter
-    private FieldNameTransformer fieldNameTransformer = s -> {
-        if (s.isEmpty()) return s;
-        char first = s.charAt(0);
-        if (Character.isUpperCase(first))
-            return Character.toLowerCase(first) + s.substring(1);
-        return s;
-    };
+    private NamingStrategy namingStrategy = NamingStrategy.FIELD_NAME;
 
     public BlueNBT() {
         register(ObjectAdapterFactory.INSTANCE);

src/main/java/de/bluecolored/bluenbt/NBTName.java

@@ -33,6 +33,11 @@
 @Target({ElementType.FIELD})
 public @interface NBTName {
 
+    /**
+     * Defines one or more nbt-names for the annotated field.<br>
+     * All names of the list will be considered during deserialization, but only the first name will be used for
+     * serialization.
+     */
     String[] value();
 
 }

src/main/java/de/bluecolored/bluenbt/NamingStrategy.java

@@ -0,0 +1,74 @@
+/*
+ * This file is part of BlueNBT, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) Blue (Lukas Rieger) <https://bluecolored.de>
+ * Copyright (c) contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package de.bluecolored.bluenbt;
+
+import java.lang.reflect.Field;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.function.Function;
+import java.util.function.UnaryOperator;
+
+@FunctionalInterface
+public interface NamingStrategy extends Function<Field, String> {
+
+    NamingStrategy FIELD_NAME = Field::getName;
+    NamingStrategy LOWER_CASE = field -> field.getName().toLowerCase();
+    NamingStrategy UPPER_CASE = field -> field.getName().toUpperCase();
+    NamingStrategy UPPER_CAMEL_CASE = field -> transformFirstLetter(field.getName(), Character::toUpperCase);
+
+    static NamingStrategy lowerCaseWithDelimiter(String delimiter) {
+        return field -> String.join(delimiter, splitCamelCase(field.getName())).toLowerCase();
+    }
+
+    static NamingStrategy upperCaseWithDelimiter(String delimiter) {
+        return field -> String.join(delimiter, splitCamelCase(field.getName())).toUpperCase();
+    }
+
+    static String[] splitCamelCase(String input) {
+        List<String> result = new ArrayList<>();
+        int start = 0;
+        for (int i = 1; i < input.length(); i++) {
+            char c = input.charAt(i);
+            if (Character.isUpperCase(c)) {
+                result.add(input.substring(start, i));
+                start = i;
+            }
+        }
+        result.add(input.substring(start));
+        return result.toArray(String[]::new);
+    }
+
+    static String transformFirstLetter(String input, UnaryOperator<Character> operation) {
+        for (int i = 0; i < input.length(); i++) {
+            char c = input.charAt(i);
+            if (!Character.isLetter(c)) continue;
+            return input.substring(0, i) + operation.apply(c) + input.substring(i + 1);
+        }
+
+        // no letters found
+        return input;
+    }
+
+}

src/main/java/de/bluecolored/bluenbt/adapter/DefaultDeserializerFactory.java

@@ -65,7 +65,6 @@ static class DefaultAdapter<T> implements TypeDeserializer<T>  {
 
         private final TypeToken<T> type;
         private final InstanceCreator<T> constructor;
-        private final BlueNBT blueNBT;
 
         private final Map<String, FieldAccessor> fields = new HashMap<>();
 
@@ -74,7 +73,6 @@ static class DefaultAdapter<T> implements TypeDeserializer<T>  {
         public DefaultAdapter(TypeToken<T> type, InstanceCreator<T> constructor, BlueNBT blueNBT) {
             this.type = type;
             this.constructor = constructor;
-            this.blueNBT = blueNBT;
 
             TypeToken<?> typeToken = type;
             Class<?> raw;
@@ -86,9 +84,9 @@ public DefaultAdapter(TypeToken<T> type, InstanceCreator<T> constructor, BlueNBT
 
                     field.setAccessible(true);
 
-                    String[] names = new String[]{ field.getName() };
+                    String[] names = new String[]{ blueNBT.getNamingStrategy().apply(field) };
                     NBTName nbtName = field.getAnnotation(NBTName.class);
-                    if (nbtName != null) names = nbtName.value();
+                    if (nbtName != null && nbtName.value().length > 0) names = nbtName.value();
 
                     TypeToken<?> fieldType = TypeToken.of(typeToken.resolve(field.getGenericType()));
 
@@ -140,11 +138,6 @@ public T read(NBTReader reader) throws IOException {
                     String name = reader.name();
                     FieldAccessor fieldInfo = fields.get(name);
 
-                    if (fieldInfo == null) {
-                        name = blueNBT.getFieldNameTransformer().apply(name);
-                        fieldInfo = fields.get(name);
-                    }
-
                     if (fieldInfo != null) {
                         fieldInfo.read(object, reader);
                     } else {

src/main/java/de/bluecolored/bluenbt/adapter/DefaultSerializerFactory.java

@@ -83,9 +83,9 @@ public DefaultAdapter(TypeToken<T> type, BlueNBT blueNBT) {
 
                     field.setAccessible(true);
 
-                    String[] names = new String[]{ field.getName() };
+                    String name = blueNBT.getNamingStrategy().apply(field);
                     NBTName nbtName = field.getAnnotation(NBTName.class);
-                    if (nbtName != null) names = nbtName.value();
+                    if (nbtName != null && nbtName.value().length > 0) name = nbtName.value()[0];
 
                     TypeToken<?> fieldType = TypeToken.of(typeToken.resolve(field.getGenericType()));
 
@@ -107,16 +107,14 @@ public DefaultAdapter(TypeToken<T> type, BlueNBT blueNBT) {
                         });
                     } else if (SPECIAL_ACCESSORS.containsKey(fieldType.getType())) {
                         FieldWriter accessor = SPECIAL_ACCESSORS.get(fieldType.getType()).apply(field);
-                        for (String name : names)
-                            fields.put(name, accessor);
+                        fields.put(name, accessor);
                         continue;
                     } else {
                         typeSerializer = blueNBT.getTypeSerializer(fieldType);
                     }
 
                     FieldWriter accessor = new TypeSerializerFieldWriter<>(field, typeSerializer);
-                    for (String name : names)
-                        fields.put(name, accessor);
+                    fields.put(name, accessor);
                 }
 
                 Type superType = typeToken.resolve(raw.getGenericSuperclass());

src/test/java/de/bluecolored/bluenbt/BlueNBTTest.java

@@ -48,6 +48,8 @@ public class BlueNBTTest {
     public void testBlueNBT() throws IOException {
 
         BlueNBT blueNBT = new BlueNBT();
+        blueNBT.setNamingStrategy(NamingStrategy.UPPER_CAMEL_CASE);
+
         try (InputStream in = NBTReaderTest.class.getResourceAsStream("/level.dat")) {
             assert in != null;
 
@@ -110,6 +112,8 @@ public void testObjectAdapter() throws IOException {
     public void testArrays() throws IOException {
 
         BlueNBT blueNBT = new BlueNBT();
+        blueNBT.setNamingStrategy(NamingStrategy.lowerCaseWithDelimiter("_"));
+
         try (InputStream in = loadMcaFileChunk(0, 0)) {
             Chunk chunk = blueNBT.read(in, TypeToken.of(Chunk.class));
 
@@ -120,10 +124,10 @@ public void testArrays() throws IOException {
             assertEquals(section.getBlockStates().getPalette().length, 26);
 
             BlockState blockState = section.getBlockStates().getPalette()[6];
-            assertEquals(blockState.getProperties().size(), 7);
-            assertEquals(blockState.getProperties().get("down"), "true");
-            assertEquals(blockState.getProperties().get("east"), "false");
-            assertEquals(blockState.getName(), "minecraft:sculk_vein");
+            assertEquals(7, blockState.getProperties().size());
+            assertEquals("true", blockState.getProperties().get("down"));
+            assertEquals("false", blockState.getProperties().get("east"));
+            assertEquals("minecraft:sculk_vein", blockState.getName());
         }
 
     }
@@ -210,9 +214,10 @@ private static class Chunk {
 
     @Data
     private static class Section {
+        @NBTName("Y")
         private int y;
-        @NBTName("block_states")
         private BlockStates blockStates = new BlockStates();
+        @NBTName("BlockLight")
         private byte[] blockLight = new byte[0];
     }
 
@@ -224,7 +229,9 @@ private static class BlockStates {
 
     @Data
     private static class BlockState {
+        @NBTName("Name")
         private String name = "minecraft:air";
+        @NBTName("Properties")
         private Map<String, String> properties = Collections.emptyMap();
     }
 
@@ -245,6 +252,7 @@ private static class DataTag extends DataTagSuper {
     private static class DataTagSuper {
         private int difficulty;
         private boolean difficultyLocked;
+        @NBTName("rainTime")
         private int rainTime;
     }