feat: finished model serialization API

Author: xEcho1337

brain4j-core/src/main/java/org/brain4j/core/importing/ModelLoaders.java

@@ -1,13 +1,23 @@
 package org.brain4j.core.importing;
 
+import org.brain4j.core.importing.impl.BrainLoader;
 import org.brain4j.core.importing.impl.OnnxLoader;
 import org.brain4j.core.model.Model;
 
+import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Paths;
 
 public class ModelLoaders {
 
+    public static Model fromFile(String path) throws Exception {
+        byte[] data = Files.readAllBytes(Paths.get(path));
+        
+        BrainLoader loader = new BrainLoader();
+        
+        return loader.deserialize(data);
+    }
+    
     public static Model fromOnnx(String path) throws Exception {
         byte[] data = Files.readAllBytes(Paths.get(path));
 

brain4j-core/src/main/java/org/brain4j/core/importing/impl/BrainLoader.java

@@ -0,0 +1,106 @@
+package org.brain4j.core.importing.impl;
+
+import org.brain4j.common.Commons;
+import org.brain4j.core.importing.ModelLoader;
+import org.brain4j.core.importing.proto.ProtoModel;
+import org.brain4j.core.layer.Layer;
+import org.brain4j.core.loss.LossFunction;
+import org.brain4j.core.model.Model;
+import org.brain4j.core.model.impl.Sequential;
+
+import java.io.*;
+import java.lang.reflect.Constructor;
+import java.time.Instant;
+import java.util.*;
+
+public class BrainLoader implements ModelLoader {
+    
+    @Override
+    public Model deserialize(byte[] bytes) throws Exception {
+        ProtoModel.Model protoModel = ProtoModel.Model.parseFrom(bytes);
+        Map<Integer, Layer> positionMap = new HashMap<>();
+        
+        for (ProtoModel.Layer layer : protoModel.getLayersList()) {
+            String layerType = layer.getType();
+            String layerId = layer.getName();
+            
+            String[] parts = layerId.split("\\.");
+            
+            if (parts.length == 0) {
+                throw new IllegalArgumentException("Layer does not match format!");
+            }
+            
+            int position = Integer.parseInt(parts[1]);
+            
+            Class<?> clazz = Class.forName(layerType);
+            
+            Constructor<?> constructor = clazz.getDeclaredConstructor();
+            constructor.setAccessible(true);
+            
+            Layer wrapped = (Layer) constructor.newInstance();
+            List<ProtoModel.Tensor> tensors = new ArrayList<>();
+            
+            for (ProtoModel.Tensor tensor : protoModel.getWeightsList()) {
+                if (!tensor.getName().startsWith(layerId)) continue;
+                
+                tensors.add(tensor);
+            }
+            
+            positionMap.put(position, wrapped);
+            wrapped.deserialize(tensors, layer);
+        }
+        
+        List<Integer> positions = new ArrayList<>(positionMap.keySet());
+        Collections.sort(positions);
+        
+        Sequential model = Sequential.of();
+        
+        for (int pos : positions) {
+            model.add(positionMap.get(pos));
+        }
+        
+        String lossFunctionClass = protoModel.getLossFunction();
+        
+        LossFunction function = Commons.newInstance(lossFunctionClass);
+        model.setLossFunction(function);
+        
+        return model;
+    }
+    
+    @Override
+    public void serialize(Model model, File file) throws IOException {
+        ProtoModel.Model.Builder builder =
+            ProtoModel.Model.newBuilder()
+                .setVersion(1)
+                .setName(file.getName())
+                .setCreated(Instant.now().toString())
+                .setLossFunction(model.lossFunction().getClass().getName());
+        
+        List<Layer> layers = model.layers();
+        
+        for (int i = 0; i < layers.size(); i++) {
+            Layer layer = layers.get(i);
+            String name = layer.getClass().getSimpleName().toLowerCase();
+            String id = name + "." + i;
+            
+            ProtoModel.Layer.Builder layerBuilder =
+                ProtoModel.Layer.newBuilder()
+                    .setName(id)
+                    .setType(layer.getClass().getName())
+                    .setDimension(layer.size());
+            
+            List<ProtoModel.Tensor.Builder> tensorsBuilders = layer.serialize(layerBuilder);
+            List<ProtoModel.Tensor> tensors = new ArrayList<>();
+            
+            for (ProtoModel.Tensor.Builder tensorBuilder : tensorsBuilders) {
+                tensorBuilder.setName(id + "." + tensorBuilder.getName());
+                tensors.add(tensorBuilder.build());
+            }
+            
+            builder.addLayers(layerBuilder.build());
+            builder.addAllWeights(tensors);
+        }
+        
+        builder.build().writeTo(new FileOutputStream(file));
+    }
+}