Use ASM to to compile extrusion pipelines

common/addons/biome-provider-extrusion/src/main/java/com/dfsek/terra/addons/biome/extrusion/BiomeExtrusionProvider.java

@@ -14,29 +14,27 @@ import com.dfsek.terra.api.world.biome.generation.BiomeProvider;
 public class BiomeExtrusionProvider implements BiomeProvider {
     private final BiomeProvider delegate;
     private final Set<Biome> biomes;
-    private final Extrusion[] extrusions;
+    private final ExtrusionPipeline pipeline;
     private final int resolution;
 
     public BiomeExtrusionProvider(BiomeProvider delegate, List<Extrusion> extrusions, int resolution) {
         this.delegate = delegate;
         this.biomes = delegate.stream().collect(Collectors.toSet());
         extrusions.forEach(e -> biomes.addAll(e.getBiomes()));
-        this.extrusions = extrusions.toArray(new Extrusion[0]);
+
+        this.pipeline = ExtrusionPipelineFactory.create(extrusions);
+
         this.resolution = resolution;
     }
 
     @Override
     public Biome getBiome(int x, int y, int z, long seed) {
         Biome delegated = delegate.getBiome(x, y, z, seed);
-
         return extrude(delegated, x, y, z, seed);
     }
 
     public Biome extrude(Biome original, int x, int y, int z, long seed) {
-        for(int i = 0; i < extrusions.length; i++) {
+        return pipeline.extrude(original, x, y, z, seed);
-            original = extrusions[i].extrude(original, x, y, z, seed);
-        }
-        return original;
     }
 
     @Override
@@ -64,4 +62,4 @@ public class BiomeExtrusionProvider implements BiomeProvider {
     public BiomeProvider getDelegate() {
         return delegate;
     }
-}
+}

common/addons/biome-provider-extrusion/src/main/java/com/dfsek/terra/addons/biome/extrusion/ExtrusionPipeline.java

@@ -0,0 +1,8 @@
+package com.dfsek.terra.addons.biome.extrusion;
+
+import com.dfsek.terra.api.world.biome.Biome;
+
+
+public interface ExtrusionPipeline {
+    Biome extrude(Biome original, int x, int y, int z, long seed);
+}

common/addons/biome-provider-extrusion/src/main/java/com/dfsek/terra/addons/biome/extrusion/ExtrusionPipelineFactory.java

@@ -0,0 +1,158 @@
+package com.dfsek.terra.addons.biome.extrusion;
+
+import org.objectweb.asm.ClassWriter;
+import org.objectweb.asm.FieldVisitor;
+import org.objectweb.asm.MethodVisitor;
+import org.objectweb.asm.Type;
+
+import java.util.List;
+import java.util.concurrent.atomic.AtomicInteger;
+
+import com.dfsek.terra.addons.biome.extrusion.api.Extrusion;
+import com.dfsek.terra.api.world.biome.Biome;
+
+import static org.objectweb.asm.Opcodes.AALOAD;
+import static org.objectweb.asm.Opcodes.ACC_FINAL;
+import static org.objectweb.asm.Opcodes.ACC_PRIVATE;
+import static org.objectweb.asm.Opcodes.ACC_PUBLIC;
+import static org.objectweb.asm.Opcodes.ALOAD;
+import static org.objectweb.asm.Opcodes.ARETURN;
+import static org.objectweb.asm.Opcodes.GETFIELD;
+import static org.objectweb.asm.Opcodes.ILOAD;
+import static org.objectweb.asm.Opcodes.INVOKEINTERFACE;
+import static org.objectweb.asm.Opcodes.INVOKESPECIAL;
+import static org.objectweb.asm.Opcodes.LLOAD;
+import static org.objectweb.asm.Opcodes.PUTFIELD;
+import static org.objectweb.asm.Opcodes.RETURN;
+import static org.objectweb.asm.Opcodes.SIPUSH;
+import static org.objectweb.asm.Opcodes.SWAP;
+import static org.objectweb.asm.Opcodes.V1_8;
+
+
+public class ExtrusionPipelineFactory {
+    private static final AtomicInteger ID_COUNTER = new AtomicInteger(0);
+
+    // Type Descriptors
+    private static final String EXTRUSION_TYPE = Type.getInternalName(Extrusion.class);
+    private static final String EXTRUSION_DESC = Type.getDescriptor(Extrusion.class);
+    private static final String BIOME_DESC = Type.getDescriptor(Biome.class);
+    private static final String PIPELINE_INTERFACE = Type.getInternalName(ExtrusionPipeline.class);
+
+    // Method Signature: (Biome, int, int, int, long) -> Biome
+    private static final String EXTRUDE_SIG = "(" + BIOME_DESC + "IIIJ)" + BIOME_DESC;
+
+    public static ExtrusionPipeline create(List<Extrusion> extrusions) {
+        // Optimization: If empty, return identity
+        if(extrusions.isEmpty()) {
+            return (original, x, y, z, seed) -> original;
+        }
+
+        String className = "com/dfsek/terra/addons/biome/extrusion/GeneratedExtrusionPipeline_" + ID_COUNTER.getAndIncrement();
+
+        ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_FRAMES | ClassWriter.COMPUTE_MAXS);
+
+        // 1. Define Class
+        cw.visit(V1_8, ACC_PUBLIC | ACC_FINAL, className, null, "java/lang/Object", new String[]{ PIPELINE_INTERFACE });
+
+        // 2. Define Fields (e0, e1, e2...)
+        for(int i = 0; i < extrusions.size(); i++) {
+            FieldVisitor fv = cw.visitField(ACC_PRIVATE | ACC_FINAL, "e" + i, EXTRUSION_DESC, null, null);
+            fv.visitEnd();
+        }
+
+        // 3. Generate Constructor(Extrusion[])
+        generateConstructor(cw, className, extrusions.size());
+
+        // 4. Generate extrude() method
+        generateExtrudeMethod(cw, className, extrusions.size());
+
+        cw.visitEnd();
+
+        // 5. Load and Instantiate
+        byte[] bytecode = cw.toByteArray();
+        try {
+            Class<?> generatedClass = new PipelineClassLoader(ExtrusionPipelineFactory.class.getClassLoader())
+                .defineClass(className.replace('/', '.'), bytecode);
+
+            return (ExtrusionPipeline) generatedClass.getConstructor(Extrusion[].class)
+                .newInstance((Object) extrusions.toArray(new Extrusion[0]));
+        } catch(Exception e) {
+            throw new RuntimeException("Failed to generate ExtrusionPipeline", e);
+        }
+    }
+
+    private static void generateConstructor(ClassWriter cw, String className, int count) {
+        MethodVisitor mv = cw.visitMethod(ACC_PUBLIC, "<init>", "([L" + EXTRUSION_TYPE + ";)V", null, null);
+        mv.visitCode();
+
+        // super()
+        mv.visitVarInsn(ALOAD, 0);
+        mv.visitMethodInsn(INVOKESPECIAL, "java/lang/Object", "<init>", "()V", false);
+
+        // Assign array elements to fields
+        for(int i = 0; i < count; i++) {
+            mv.visitVarInsn(ALOAD, 0);          // Load this
+            mv.visitVarInsn(ALOAD, 1);          // Load array argument
+            mv.visitIntInsn(SIPUSH, i);         // Load index
+            mv.visitInsn(AALOAD);               // Load array[i]
+            mv.visitFieldInsn(PUTFIELD, className, "e" + i, EXTRUSION_DESC);
+        }
+
+        mv.visitInsn(RETURN);
+        mv.visitMaxs(0, 0); // Computed automatically
+        mv.visitEnd();
+    }
+
+    private static void generateExtrudeMethod(ClassWriter cw, String className, int count) {
+        MethodVisitor mv = cw.visitMethod(ACC_PUBLIC, "extrude", EXTRUDE_SIG, null, null);
+        mv.visitCode();
+
+        // Helper var indices:
+        // 0: this
+        // 1: Biome original (We will update this or chain it on stack)
+        // 2: int x
+        // 3: int y
+        // 4: int z
+        // 5: long seed
+
+        mv.visitVarInsn(ALOAD, 1); // Load 'original' Biome onto stack initially
+
+        for(int i = 0; i < count; i++) {
+            // Stack contains: [CurrentBiome]
+
+            mv.visitVarInsn(ALOAD, 0); // Load 'this'
+            mv.visitFieldInsn(GETFIELD, className, "e" + i, EXTRUSION_DESC); // Load Extrusion field
+
+            // Stack: [CurrentBiome, Extrusion]
+            // We need: [Extrusion, CurrentBiome, x, y, z, seed]
+
+            mv.visitInsn(SWAP); // Swap to get [Extrusion, CurrentBiome]
+
+            mv.visitVarInsn(ILOAD, 2); // x
+            mv.visitVarInsn(ILOAD, 3); // y
+            mv.visitVarInsn(ILOAD, 4); // z
+            mv.visitVarInsn(LLOAD, 5); // seed
+
+            // Invoke Extrusion.extrude(Biome, x, y, z, seed)
+            mv.visitMethodInsn(INVOKEINTERFACE, EXTRUSION_TYPE, "extrude", EXTRUDE_SIG, true);
+
+            // Stack now contains: [NewBiome]
+            // Loop continues using this result as input for the next one
+        }
+
+        mv.visitInsn(ARETURN); // Return the final Biome
+        mv.visitMaxs(0, 0);
+        mv.visitEnd();
+    }
+
+    // Custom ClassLoader to inject the bytes
+    private static class PipelineClassLoader extends ClassLoader {
+        public PipelineClassLoader(ClassLoader parent) {
+            super(parent);
+        }
+
+        public Class<?> defineClass(String name, byte[] b) {
+            return defineClass(name, b, 0, b.length);
+        }
+    }
+}