#include <stdlib.h>

#define NAPI_EXPERIMENTAL

#include <node_api.h>

#define NAPI_CALL(env, call) \

do { \

napi_status status = (call); \

if (status != napi_ok) { \

napi_throw_error((env), NULL, #call " failed"); \

return NULL; \

} \

} while (0)

static napi_value

GetCount(napi_env env, napi_callback_info info) {

napi_value result;

size_t* count;

NAPI_CALL(env, napi_get_instance_data(env, (void**)&count));

NAPI_CALL(env, napi_create_uint32(env, *count, &result));

return result;

}

static napi_value

SetCount(napi_env env, napi_callback_info info) {

size_t* count;

NAPI_CALL(env, napi_get_instance_data(env, (void**)&count));

// Set the count to zero irrespective of what is passed into the setter.

*count = 0;

return NULL;

}

static void

IncrementCounter(napi_env env, void* data, void* hint) {

size_t* count = data;

(*count) = (*count) + 1;

}

static napi_value

NewWeak(napi_env env, napi_callback_info info) {

napi_value result;

void* instance_data;

NAPI_CALL(env, napi_create_object(env, &result));

NAPI_CALL(env, napi_get_instance_data(env, &instance_data));

NAPI_CALL(env, napi_add_finalizer(env,

result,

instance_data,

IncrementCounter,

NULL,

NULL));

return result;

}

static void

FreeCount(napi_env env, void* data, void* hint) {

free(data);

}

NAPI_MODULE_INIT(/* napi_env env, napi_value exports */) {

napi_property_descriptor props[] = {

{ "count", NULL, NULL, GetCount, SetCount, NULL, napi_enumerable, NULL },

{ "newWeak", NULL, NewWeak, NULL, NULL, NULL, napi_enumerable, NULL }

};

size_t* count = malloc(sizeof(*count));

*count = 0;

NAPI_CALL(env, napi_define_properties(env,

exports,

sizeof(props) / sizeof(*props),

props));

NAPI_CALL(env, napi_set_instance_data(env, count, FreeCount, NULL));

return exports;

}