@Layout
public interface ArrayLayout {

    DynamicObject createArray(Object store, int size);

    boolean isArray(DynamicObject object);

    Object getStore(DynamicObject object);

    void setStore(DynamicObject object, Object store);

    int getSize(DynamicObject object);

    void setSize(DynamicObject object, int size);

}

package org.jruby.truffle.nodes.core.array;

import java.util.EnumSet;
import com.oracle.truffle.api.object.*;
import org.jruby.truffle.om.dsl.api.UnexpectedLayoutRefusalException;
import org.jruby.truffle.nodes.core.array.ArrayNodes.ArrayLayout;

public class ArrayLayoutImpl implements ArrayLayout {

    public static final ArrayLayout INSTANCE = new ArrayLayoutImpl();

    private static class ArrayType extends ObjectType {

    }

    private final ArrayType ARRAY_TYPE = new ArrayType();

    private final HiddenKey STORE_IDENTIFIER = new HiddenKey("store");
    private final Property STORE_PROPERTY;

    private final HiddenKey SIZE_IDENTIFIER = new HiddenKey("size");
    private final Property SIZE_PROPERTY;

    private final DynamicObjectFactory ARRAY_FACTORY;

    private ArrayLayoutImpl() {
        final Layout layout = Layout.createLayout(Layout.INT_TO_LONG);
        final Shape.Allocator allocator = layout.createAllocator();

        STORE_PROPERTY = Property.create(STORE_IDENTIFIER, allocator.locationForType(java.lang.Object.class, EnumSet.of(LocationModifier.NonNull)), 0);
        SIZE_PROPERTY = Property.create(SIZE_IDENTIFIER, allocator.locationForType(int.class, EnumSet.of(LocationModifier.NonNull)), 0);

        final Shape shape = layout.createShape(ARRAY_TYPE)
            .addProperty(STORE_PROPERTY)
            .addProperty(SIZE_PROPERTY);

        ARRAY_FACTORY = shape.createFactory();
    }

    @Override
    public DynamicObject createArray(java.lang.Object store,
            int size) {
        return ARRAY_FACTORY.newInstance(store,
            size);
    }

    @Override
    public boolean isArray(DynamicObject object) {
        return object.getShape().getObjectType() == ARRAY_TYPE;
    }

    @Override
    public java.lang.Object getStore(DynamicObject object) {
        assert isArray(object);
        assert object.getShape().hasProperty(STORE_IDENTIFIER);

        return (java.lang.Object) STORE_PROPERTY.get(object, true);
    }

    @Override
    public void setStore(DynamicObject object, java.lang.Object value) {
        assert isArray(object);
        assert object.getShape().hasProperty(STORE_IDENTIFIER);

        try {
            STORE_PROPERTY.set(object, value, object.getShape());
        } catch (IncompatibleLocationException | FinalLocationException e) {
            throw new UnexpectedLayoutRefusalException(e);
        }
    }

    @Override
    public int getSize(DynamicObject object) {
        assert isArray(object);
        assert object.getShape().hasProperty(SIZE_IDENTIFIER);

        return (int) SIZE_PROPERTY.get(object, true);
    }

    @Override
    public void setSize(DynamicObject object, int value) {
        assert isArray(object);
        assert object.getShape().hasProperty(SIZE_IDENTIFIER);

        try {
            SIZE_PROPERTY.set(object, value, object.getShape());
        } catch (IncompatibleLocationException | FinalLocationException e) {
            throw new UnexpectedLayoutRefusalException(e);
        }
    }

}