napi-rs/napi-derive-example/src/lib.rs

#[macro_use]
extern crate napi_rs as napi;
#[macro_use]
extern crate napi_derive;

use napi::{Any, Env, Error, Object, Result, Status, Value, CallContext, Number};
use std::convert::TryInto;

register_module!(test_module, init);

fn init<'env>(
  env: &'env Env,
  exports: &'env mut Value<'env, Object>,
) -> Result<Option<Value<'env, Object>>> {
  exports.set_named_property(
    "testThrow",
    env.create_function("testThrow", test_throw)?,
  )?;

  exports.set_named_property(
    "fibonacci",
    env.create_function("fibonacci", fibonacci)?,
  )?;
  Ok(None)
}

#[js_function]
fn test_throw<'a>(
  _ctx: CallContext,
) -> Result<Value<'a, Any>> {
  Err(Error::new(Status::GenericFailure))
}

#[js_function]
fn fibonacci<'env>(ctx: CallContext<'env>) -> Result<Value<'env, Number>> {
  let n = ctx.get::<Number>(0)?.try_into()?;
  ctx.env.create_int64(fibonacci_native(n))
}

#[inline]
fn fibonacci_native(n: i64) -> i64 {
  match n {
    1 | 2 => 1,
    _ => fibonacci_native(n - 1) + fibonacci_native(n - 2)
  }
}