Add collection support #4

Author: Bethibande

README.md

@@ -56,7 +56,7 @@ For more examples see [here](/example/src/main/java/de/bethibande/serial/example
 | String / CharSequence    | ✅       |
 | Any enum type            | ✅       |
 | Arrays                   | ✅       |
-| Collections              | 💡      |
+| Collections              | ✅       |
 | Maps                     | 💡      |
 | Other serializable types | ❌       |
 | Java time types          | ❌       |

core/src/main/java/de/bethibande/serial/allocation/ParameterizedObjectAllocator.java

@@ -0,0 +1,8 @@
+package de.bethibande.serial.allocation;
+
+@FunctionalInterface
+public interface ParameterizedObjectAllocator<P, T> {
+
+    T allocate(final P parameter);
+
+}

example/src/main/java/de/bethibande/serial/example/Main.java

@@ -7,17 +7,22 @@
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.ByteBufAllocator;
 
+import java.util.ArrayList;
+import java.util.List;
+
 public class Main {
 
     public static void main(String[] args) {
-        final ByteBuf buffer = ByteBufAllocator.DEFAULT.buffer(12);
+        final ByteBuf buffer = ByteBufAllocator.DEFAULT.buffer(32);
         final Writer writer = new NettyWriter(buffer);
         final Reader reader = new NettyReader(buffer);
 
         final TestDTO test = new TestDTO();
         test.setSomeString("abc");
+        test.setStringList(List.of("a", "b", "c"));
         final TestDTOSerializer serializer = new TestDTOSerializer();
         final TestDTODeserializer deserializer = new TestDTODeserializer();
+        deserializer.stringListNotNullAllocator(ArrayList::new);
 
         serializer.bind(writer)
                 .write(test.withSomeNumber(234))

example/src/main/java/de/bethibande/serial/example/TestDTO.java

@@ -6,6 +6,9 @@
 import lombok.ToString;
 import org.jetbrains.annotations.NotNull;
 
+import java.util.Collection;
+import java.util.List;
+
 @Getter
 @Setter
 @ToString
@@ -19,9 +22,10 @@ public class TestDTO {
     @SuppressWarnings("boxedtypes")
     private Integer someInteger;
     private MyEnum someEnum;
-    @Getter
     private @NotNull String[] someStringArray;
 
+    private List<String> stringList;
+
     // We need to prevent the default lombok setter here, since lombok handles annotations incorrectly adding a null-check that shouldn't be there.
     public void setSomeStringArray(final String[] someStringArray) {
         this.someStringArray = someStringArray;

processor/src/main/java/de/bethibande/serial/processor/TypeHelper.java

@@ -61,6 +61,14 @@ public static TypeMirror asType(final Class<?> clazz) {
         return asElement(clazz).asType();
     }
 
+    public static TypeMirror erasure(final TypeMirror type) {
+        return SerializationProcessor.TYPES.get().erasure(type);
+    }
+
+    public static boolean is(final TypeMirror a, final TypeMirror b) {
+        return SerializationProcessor.TYPES.get().isSameType(a, b);
+    }
+
     public static boolean isCharSequence(final TypeMirror type) {
         return SerializationProcessor.TYPES.get().isSubtype(type, asType(CharSequence.class));
     }

processor/src/main/java/de/bethibande/serial/processor/serializer/types/CollectionTypes.java

@@ -0,0 +1,101 @@
+package de.bethibande.serial.processor.serializer.types;
+
+import com.google.auto.service.AutoService;
+import com.palantir.javapoet.*;
+import de.bethibande.serial.allocation.ParameterizedObjectAllocator;
+import de.bethibande.serial.processor.TypeHelper;
+import de.bethibande.serial.processor.context.SerializationContext;
+import de.bethibande.serial.processor.generator.FieldInfo;
+import de.bethibande.serial.processor.serializer.ElementSerializer;
+import de.bethibande.serial.processor.serializer.EmbeddedTypeTransformer;
+import de.bethibande.serial.processor.serializer.FieldBasedObjectTransformer;
+
+import javax.lang.model.element.Modifier;
+import javax.lang.model.type.DeclaredType;
+import javax.lang.model.type.TypeMirror;
+import java.util.Collection;
+import java.util.Optional;
+
+@AutoService(FieldBasedObjectTransformer.class)
+public class CollectionTypes extends EmbeddedTypeTransformer {
+
+    @Override
+    protected boolean isApplicable0(final FieldInfo field) {
+        return !field.isNullable() && TypeHelper.isAssignable(TypeHelper.erasure(field.getType()), TypeHelper.asType(Collection.class));
+    }
+
+    @Override
+    protected FieldInfo createChildType(final FieldInfo field, final ElementSerializer serializer) {
+        if (field.getType() instanceof DeclaredType declaredType) {
+            final TypeMirror type = declaredType.getTypeArguments().getFirst();
+
+            return field.toBuilder()
+                    .type(type)
+                    .nullable(TypeHelper.isNullable(type))
+                    .build();
+        }
+        throw new IllegalArgumentException("Type is not a declared type");
+    }
+
+    @Override
+    public CodeBlock createSerializationCode(final FieldInfo field, final SerializationContext ctx) {
+        return CodeBlock.builder()
+                .addStatement("$L.writeInt($L.size())", FIELD_WRITER, FIELD_VALUE)
+                .beginControlFlow("for ($T item : $L)", field.getFirstChild().getType(), FIELD_VALUE)
+                .addStatement("$L(item)", embeddedMethodName(field))
+                .endControlFlow()
+                .addStatement("return this")
+                .build();
+    }
+
+    protected String allocatorFieldName(final FieldInfo field) {
+        return methodName(field) + "Allocator";
+    }
+
+    @Override
+    public Optional<String> wrappedMethodNameSuffix() {
+        return Optional.of("CollectionValue");
+    }
+
+    @Override
+    public void applyDeserializerTransformation(final TypeSpec.Builder builder,
+                                                final FieldInfo field,
+                                                final SerializationContext ctx) {
+        final TypeName fieldType = TypeName.get(field.getType());
+        final TypeName allocatorType = ParameterizedTypeName.get(
+                ClassName.get(ParameterizedObjectAllocator.class),
+                ClassName.get(Integer.class),
+                fieldType
+        );
+        final String allocatorFieldName = allocatorFieldName(field);
+
+        final FieldSpec allocatorField = FieldSpec.builder(allocatorType, allocatorFieldName)
+                .addModifiers(Modifier.PRIVATE)
+                .build();
+
+        final MethodSpec allocatorMethod = MethodSpec.methodBuilder(allocatorFieldName)
+                .addModifiers(Modifier.PUBLIC)
+                .addParameter(ParameterSpec.builder(allocatorType, allocatorFieldName)
+                        .addModifiers(Modifier.FINAL)
+                        .build())
+                .addStatement("this.$L = $L", allocatorFieldName, allocatorFieldName)
+                .addStatement("return this")
+                .returns(ctx.deserializerType())
+                .build();
+
+        builder.addField(allocatorField);
+        builder.addMethod(allocatorMethod);
+    }
+
+    @Override
+    public CodeBlock createDeserializationCode(final FieldInfo field, final SerializationContext ctx) {
+        return CodeBlock.builder()
+                .addStatement("final int length = $L.readInt()", FIELD_READER)
+                .addStatement("final $T $L = $L.allocate(length)", field.getType(), FIELD_VALUE, allocatorFieldName(field))
+                .beginControlFlow("for (int i = 0; i < length; i++)")
+                .addStatement("$L.add($L())", FIELD_VALUE, embeddedMethodName(field))
+                .endControlFlow()
+                .addStatement("return $L", FIELD_VALUE)
+                .build();
+    }
+}