Java 8, FunctionalInterface remapper

common/src/main/java/us/myles/ViaVersion/api/remapper/PacketHandler.java

@@ -3,17 +3,18 @@ package us.myles.ViaVersion.api.remapper;
 import us.myles.ViaVersion.api.PacketWrapper;
 import us.myles.ViaVersion.exception.InformativeException;
 
-public abstract class PacketHandler implements ValueWriter {
+@FunctionalInterface
+public interface PacketHandler extends ValueWriter {
     /**
      * Handle a packet
      *
      * @param wrapper The associated wrapper
      * @throws Exception Throws exception if it failed to handle the packet
      */
-    public abstract void handle(PacketWrapper wrapper) throws Exception;
+    void handle(PacketWrapper wrapper) throws Exception;
 
     @Override
-    public void write(PacketWrapper writer, Object inputValue) throws Exception {
+    default void write(PacketWrapper writer, Object inputValue) throws Exception {
         try {
             handle(writer);
         } catch (InformativeException e) {

common/src/main/java/us/myles/ViaVersion/api/remapper/PacketRemapper.java

@@ -7,6 +7,7 @@ import us.myles.ViaVersion.exception.InformativeException;
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.function.Function;
 
 public abstract class PacketRemapper {
     private final List<Pair<ValueReader, ValueWriter>> valueRemappers = new ArrayList<>();
@@ -35,6 +36,36 @@ public abstract class PacketRemapper {
         map(new TypeRemapper(oldType), new TypeRemapper(newType));
     }
 
+    /**
+     * Map a type from an old type to a transformed new type.
+     *
+     * @param oldType     The old type
+     * @param <T1>        The old return type.
+     * @param newType     The new type
+     * @param <T2>        The new return type.
+     * @param transformer The transformer to use to produce the new type.
+     */
+    public <T1, T2> void map(Type<T1> oldType, Type<T2> newType, Function<T1, T2> transformer) {
+        map(new TypeRemapper<>(oldType), new ValueTransformer<T1, T2>(newType) {
+            @Override
+            public T2 transform(PacketWrapper wrapper, T1 inputValue) throws Exception {
+                return transformer.apply(inputValue);
+            }
+        });
+    }
+
+    /**
+     * Map a type from an old type to a transformed new type.
+     *
+     * @param <T1>        The old return type.
+     * @param transformer The transformer to use to produce the new type.
+     * @param <T2>        The new return type.
+     */
+    public <T1, T2> void map(ValueTransformer<T1, T2> transformer) {
+        if (transformer.getInputType() == null) throw new IllegalArgumentException("Use map(Type<T1>, ValueTransformer<T1, T2>) for value transformers without specified input type!");
+        map(transformer.getInputType(), transformer);
+    }
+
     /**
      * Map a type from an old type to a transformed new type.
      *
@@ -55,7 +86,7 @@ public abstract class PacketRemapper {
      * @param <T>          The return type
      */
     public <T> void map(ValueReader<T> inputReader, ValueWriter<T> outputWriter) {
-        valueRemappers.add(new Pair<ValueReader, ValueWriter>(inputReader, outputWriter));
+        valueRemappers.add(new Pair<>(inputReader, outputWriter));
     }
 
     /**

common/src/main/java/us/myles/ViaVersion/api/remapper/ValueCreator.java

@@ -3,17 +3,18 @@ package us.myles.ViaVersion.api.remapper;
 import us.myles.ViaVersion.api.PacketWrapper;
 import us.myles.ViaVersion.exception.InformativeException;
 
-public abstract class ValueCreator implements ValueWriter {
+@FunctionalInterface
+public interface ValueCreator extends ValueWriter {
     /**
      * Write new values to a Packet.
      *
      * @param wrapper The packet to write to
      * @throws Exception Throws exception if it fails to write.
      */
-    public abstract void write(PacketWrapper wrapper) throws Exception;
+    void write(PacketWrapper wrapper) throws Exception;
 
     @Override
-    public void write(PacketWrapper writer, Object inputValue) throws Exception {
+    default void write(PacketWrapper writer, Object inputValue) throws Exception {
         try {
             write(writer);
         } catch (InformativeException e) {

common/src/main/java/us/myles/ViaVersion/api/remapper/ValueReader.java

@@ -2,6 +2,7 @@ package us.myles.ViaVersion.api.remapper;
 
 import us.myles.ViaVersion.api.PacketWrapper;
 
+@FunctionalInterface
 public interface ValueReader<T> {
     /**
      * Reads value from a PacketWrapper

common/src/main/java/us/myles/ViaVersion/api/remapper/ValueTransformer.java

@@ -1,16 +1,24 @@
 package us.myles.ViaVersion.api.remapper;
 
+import lombok.Getter;
 import us.myles.ViaVersion.api.PacketWrapper;
 import us.myles.ViaVersion.api.type.Type;
 import us.myles.ViaVersion.exception.InformativeException;
 
 public abstract class ValueTransformer<T1, T2> implements ValueWriter<T1> {
+    @Getter
+    private final Type<T1> inputType;
     private final Type<T2> outputType;
 
-    public ValueTransformer(Type<T2> outputType) {
+    public ValueTransformer(Type<T1> inputType, Type<T2> outputType) {
+        this.inputType = inputType;
         this.outputType = outputType;
     }
 
+    public ValueTransformer(Type<T2> outputType) {
+        this(null, outputType);
+    }
+
     /**
      * Transform a value from one type to another
      *

common/src/main/java/us/myles/ViaVersion/api/remapper/ValueWriter.java

@@ -2,6 +2,7 @@ package us.myles.ViaVersion.api.remapper;
 
 import us.myles.ViaVersion.api.PacketWrapper;
 
+@FunctionalInterface
 public interface ValueWriter<T> {
     /**
      * Write a value to a packet

common/src/main/java/us/myles/ViaVersion/protocols/protocol1_9to1_8/PlayerMovementMapper.java

@@ -5,7 +5,7 @@ import us.myles.ViaVersion.api.remapper.PacketHandler;
 import us.myles.ViaVersion.api.type.Type;
 import us.myles.ViaVersion.protocols.protocol1_9to1_8.storage.MovementTracker;
 
-public class PlayerMovementMapper extends PacketHandler {
+public class PlayerMovementMapper implements PacketHandler {
     @Override
     public void handle(PacketWrapper wrapper) throws Exception {
         MovementTracker tracker = wrapper.user().get(MovementTracker.class);

pom.xml

@@ -34,8 +34,8 @@
         <projectEncoding>UTF-8</projectEncoding>
         <project.build.sourceEncoding>${projectEncoding}</project.build.sourceEncoding>
         <project.build.outputEncoding>${projectEncoding}</project.build.outputEncoding>
-        <maven.compiler.source>1.7</maven.compiler.source>
-        <maven.compiler.target>1.7</maven.compiler.target>
+        <maven.compiler.source>1.8</maven.compiler.source>
+        <maven.compiler.target>1.8</maven.compiler.target>
     </properties>
 
     <repositories>