Trait napi::bindgen_prelude::Generator

pub trait Generator {
    type Yield: ToNapiValue;
    type Next: FromNapiValue;
    type Return: FromNapiValue;

    fn next(&mut self, value: Option<Self::Next>) -> Option<Self::Yield>;

    fn complete(&mut self, value: Option<Self::Return>) -> Option<Self::Yield> { ... }
    fn catch(
        &mut self,
        env: Env,
        value: Unknown
    ) -> Result<Option<Self::Yield>, Unknown> { ... }
}

Implement a Iterator for the JavaScript Class. This feature is an experimental feature and is not yet stable.

Required Associated Types

type Yield: ToNapiValue

type Next: FromNapiValue

type Return: FromNapiValue

Required Methods

fn next(&mut self, value: Option<Self::Next>) -> Option<Self::Yield>

Handle the Generator.next() https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Generator/next

Provided Methods

fn complete(&mut self, value: Option<Self::Return>) -> Option<Self::Yield>

Implement complete to handle the Generator.return() https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Generator/return

Examples found in repository

src/bindgen_runtime/iterator.rs (line 358)

extern "C" fn generator_return<T: Generator>(
  env: sys::napi_env,
  info: sys::napi_callback_info,
) -> sys::napi_value {
  let mut this = ptr::null_mut();
  let mut argv: [sys::napi_value; 1] = [ptr::null_mut()];
  let mut argc = 1;
  let mut generator_ptr = ptr::null_mut();
  check_status_or_throw!(
    env,
    unsafe {
      sys::napi_get_cb_info(
        env,
        info,
        &mut argc,
        argv.as_mut_ptr(),
        &mut this,
        &mut generator_ptr,
      )
    },
    "Get callback info from generator function failed"
  );

  let g = unsafe { Box::leak(Box::from_raw(generator_ptr as *mut T)) };
  if argc == 0 {
    g.complete(None);
  } else {
    g.complete(Some(
      match unsafe { T::Return::from_napi_value(env, argv[0]) } {
        Ok(input) => input,
        Err(e) => {
          unsafe {
            sys::napi_throw_error(
              env,
              format!("{}", e.status).as_ptr() as *mut c_char,
              e.reason.as_ptr() as *mut c_char,
            )
          };
          return ptr::null_mut();
        }
      },
    ));
  }
  let mut generator_state = ptr::null_mut();
  check_status_or_throw!(
    env,
    unsafe { sys::napi_get_boolean(env, true, &mut generator_state) },
    "Create generator state failed"
  );
  check_status_or_throw!(
    env,
    unsafe {
      sys::napi_set_named_property(
        env,
        this,
        GENERATOR_STATE_KEY.as_ptr() as *const c_char,
        generator_state,
      )
    },
    "Get generator state failed"
  );
  let mut result = std::ptr::null_mut();
  check_status_or_throw!(
    env,
    unsafe { sys::napi_create_object(env, &mut result) },
    "Failed to create iterator result object",
  );
  if argc > 0 {
    check_status_or_throw!(
      env,
      unsafe {
        sys::napi_set_named_property(
          env,
          result,
          "value\0".as_ptr() as *const std::os::raw::c_char,
          argv[0],
        )
      },
      "Failed to set iterator result value",
    );
  }
  check_status_or_throw!(
    env,
    unsafe {
      sys::napi_set_named_property(
        env,
        result,
        "done\0".as_ptr() as *const std::os::raw::c_char,
        generator_state,
      )
    },
    "Failed to set iterator result done",
  );

  result
}

fn catch(
    &mut self,
    env: Env,
    value: Unknown
) -> Result<Option<Self::Yield>, Unknown>

Implement catch to handle the Generator.throw() https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Generator/throw

Examples found in repository

src/bindgen_runtime/iterator.rs (lines 461-468)

extern "C" fn generator_throw<T: Generator>(
  env: sys::napi_env,
  info: sys::napi_callback_info,
) -> sys::napi_value {
  let mut this = ptr::null_mut();
  let mut argv: [sys::napi_value; 1] = [ptr::null_mut()];
  let mut argc = 1;
  let mut generator_ptr = ptr::null_mut();
  check_status_or_throw!(
    env,
    unsafe {
      sys::napi_get_cb_info(
        env,
        info,
        &mut argc,
        argv.as_mut_ptr(),
        &mut this,
        &mut generator_ptr,
      )
    },
    "Get callback info from generator function failed"
  );

  let g = unsafe { Box::leak(Box::from_raw(generator_ptr as *mut T)) };
  let catch_result = if argc == 0 {
    let mut undefined = ptr::null_mut();
    check_status_or_throw!(
      env,
      unsafe { sys::napi_get_undefined(env, &mut undefined) },
      "Get undefined failed"
    );
    g.catch(
      Env(env),
      Unknown(Value {
        env,
        value: undefined,
        value_type: crate::ValueType::Undefined,
      }),
    )
  } else {
    g.catch(
      Env(env),
      Unknown(Value {
        env,
        value: argv[0],
        value_type: crate::ValueType::Unknown,
      }),
    )
  };
  let mut result = ptr::null_mut();
  check_status_or_throw!(
    env,
    unsafe { sys::napi_create_object(env, &mut result) },
    "Failed to create iterator result object",
  );
  let mut generator_state = ptr::null_mut();
  let mut generator_state_value = false;
  match catch_result {
    Err(e) => {
      generator_state_value = true;
      check_status_or_throw!(
        env,
        unsafe { sys::napi_get_boolean(env, generator_state_value, &mut generator_state) },
        "Create generator state failed"
      );
      check_status_or_throw!(
        env,
        unsafe {
          sys::napi_set_named_property(
            env,
            this,
            GENERATOR_STATE_KEY.as_ptr() as *const c_char,
            generator_state,
          )
        },
        "Get generator state failed"
      );
      let throw_status = unsafe { sys::napi_throw(env, e.0.value) };
      debug_assert!(
        throw_status == sys::Status::napi_ok,
        "Failed to throw error {}",
        crate::Status::from(throw_status)
      );
      return ptr::null_mut();
    }
    Ok(Some(v)) => {
      set_generator_value(env, result, v);
    }
    Ok(None) => {
      generator_state_value = true;
    }
  }
  check_status_or_throw!(
    env,
    unsafe { sys::napi_get_boolean(env, generator_state_value, &mut generator_state) },
    "Create generator state failed"
  );
  check_status_or_throw!(
    env,
    unsafe {
      sys::napi_set_named_property(
        env,
        this,
        GENERATOR_STATE_KEY.as_ptr() as *const c_char,
        generator_state,
      )
    },
    "Get generator state failed"
  );
  check_status_or_throw!(
    env,
    unsafe {
      sys::napi_set_named_property(
        env,
        result,
        "done\0".as_ptr() as *const c_char,
        generator_state,
      )
    },
    "Get generator state failed"
  );

  result
}

Implementors