alef-backend-java 0.16.21

package {{ package }};

import java.lang.foreign.Arena;
import java.lang.foreign.FunctionDescriptor;
import java.lang.foreign.Linker;
import java.lang.foreign.MemorySegment;
import java.lang.foreign.ValueLayout;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodType;
{% if needs_list_import %}import java.util.List;
{% endif %}{% if needs_map_import %}import java.util.Map;
{% endif %}import java.util.concurrent.ConcurrentHashMap;
import com.fasterxml.jackson.databind.ObjectMapper;

/**
 * Allocates Panama FFM upcall stubs for an I{{ trait_pascal }} implementation,
 * assembles the C vtable in native memory, and provides static
 * register{{ trait_pascal }}/unregister{{ trait_pascal }} helpers.
 */
public final class {{ bridge_class }} implements AutoCloseable {

    private static final Linker LINKER = Linker.nativeLinker();
    private static final MethodHandles.Lookup LOOKUP = MethodHandles.lookup();
    private static final ObjectMapper JSON = new ObjectMapper();

    /** Live registry — keeps Arenas and upcall stubs alive past the register call. */
    private static final ConcurrentHashMap<String, {{ bridge_class }}>
            {{ registry_field }} = new ConcurrentHashMap<>();

    // C vtable: {{ num_vtable_fields }} fields ({{ num_super_slots }} plugin methods + {{ num_methods }} trait methods + free_user_data)
    private static final long VTABLE_SIZE = (long) ValueLayout.ADDRESS.byteSize() * {{ num_vtable_fields }}L;

    private final Arena arena;
    private final MemorySegment vtable;
    private final I{{ trait_pascal }} impl;