Struct JsExternal

pub struct JsExternal<T>(/* private fields */);

Implementations

impl<T> JsExternal<T>

pub fn new( env: NapiEnv, value: T, finalizer: impl FnOnce(NapiEnv, T) -> NapiResult<()> + 'static, ) -> NapiResult<JsExternal<T>>

This API allocates a JavaScript value with external data attached to it. This is used to pass external data through JavaScript code, so it can be retrieved later by native code using napi_get_value_external.

pub fn get(&self) -> NapiResult<&mut T>

Access the underlaying data.

pub fn arraybuffer<'a>( env: NapiEnv, value: impl AsRef<[T]>, ) -> NapiResult<JsExternal<&'a [T]>>

This API returns a Node-API value corresponding to a JavaScript ArrayBuffer. The underlying byte buffer of the ArrayBuffer is externally allocated and managed. The caller must ensure that the byte buffer remains valid until the finalize callback is called. The API adds a napi_finalize callback which will be called when the JavaScript object just created is ready for garbage collection. It is similar to napi_wrap() except that:

• the native data cannot be retrieved later using napi_unwrap(),
• nor can it be removed later using napi_remove_wrap(), and
• the object created by the API can be used with napi_wrap(). JavaScript ArrayBuffers are described in Section 24.1 of the ECMAScript Language Specification.

pub fn buffer<'a>( env: NapiEnv, value: impl AsRef<[T]>, ) -> NapiResult<JsExternal<&'a [T]>>

This API allocates a node::Buffer object and initializes it with data backed by the passed in buffer. While this is still a fully-supported data structure, in most cases using a TypedArray will suffice. The API adds a napi_finalize callback which will be called when the JavaScript object just created is ready for garbage collection. It is similar to napi_wrap() except that:

• the native data cannot be retrieved later using napi_unwrap(),
• nor can it be removed later using napi_remove_wrap(), and
• the object created by the API can be used with napi_wrap(). For Node.js >=4 Buffers are Uint8Arrays.

Trait Implementations

impl<T: Clone> Clone for JsExternal<T>

fn clone(&self) -> JsExternal<T>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T: Debug> Debug for JsExternal<T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T> NapiValueCheck for JsExternal<T>

fn check(&self) -> NapiResult<bool>

impl<T> NapiValueT for JsExternal<T>

fn from_raw(env: NapiEnv, raw: napi_value) -> JsExternal<T>

construct value from raw pointer

fn value(&self) -> JsValue

inner value

unsafe fn cast<T: NapiValueT>(&self) -> T

napi_value type cast

fn cast_checked<T: NapiValueT>(&self) -> NapiResult<T>

Upcast to specified value

fn kind(&self) -> NapiResult<NapiValuetype>

Returns napi_ok if the API succeeded.

fn coerce_to_bool(&self) -> NapiResult<JsBoolean>

This API implements the abstract operation ToBoolean() as defined in Section 7.1.2 of the ECMAScript Language Specification.

fn coerce_coerce_to_number(&self) -> NapiResult<JsNumber>

This API implements the abstract operation ToNumber() as defined in Section 7.1.3 of the ECMAScript Language Specification. This function potentially runs JS code if the passed-in value is an object.

fn coerce_to_object(&self) -> NapiResult<JsObject>

This API implements the abstract operation ToObject() as defined in Section 7.1.13 of the ECMAScript Language Specification.

fn coerce_to_string(&self) -> NapiResult<JsString>

This API implements the abstract operation ToString() as defined in Section 7.1.13 of the ECMAScript Language Specification. This function potentially runs JS code if the passed-in value is an object.

fn instance_of(&self, constructor: JsFunction) -> NapiResult<bool>

This API represents invoking the instanceof Operator on the object as defined in Section 12.10.4 of the ECMAScript Language Specification.

fn equals(&self, rhs: impl NapiValueT) -> NapiResult<bool>

This API represents the invocation of the Strict Equality algorithm as defined in Section 7.2.14 of the ECMAScript Language Specification.

fn env(&self) -> NapiEnv

the NapiEnv of current value

fn raw(&self) -> napi_value

the raw-handle of current value

fn null(&self) -> NapiResult<JsNull>

get null singleton

fn undefined(&self) -> NapiResult<JsUndefined>

get undefined singleton

fn global(&self) -> NapiResult<JsGlobal>

get global singleton

fn throw(&self) -> NapiResult<()>

value is throwable

fn define_properties<P>(&self, properties: P) -> NapiResult<()>

where P: AsRef<[NapiPropertyDescriptor]>,

This method allows the efficient definition of multiple properties on a given object. The properties are defined using property descriptors (see napi_property_descriptor). Given an array of such property descriptors, this API will set the properties on the object one at a time, as defined by DefineOwnProperty() (described in Section 9.1.6 of the ECMA-262 specification).

fn gc<Finalizer>(&mut self, finalizer: Finalizer) -> NapiResult<NapiRef>

where Finalizer: FnOnce(NapiEnv) -> NapiResult<()>,

This is a hook which is fired when the value is gabage-collected. For napi >= 5, we use napi_add_finalizer, For napi < 5, we use napi_wrap.

fn finalizer<Finalizer>(&self, finalizer: Finalizer) -> NapiResult<NapiRef>

where Finalizer: FnOnce(NapiEnv) -> NapiResult<()>,

Adds a napi_finalize callback which will be called when the JavaScript object in js_object is ready for garbage collection. This API is similar to napi_wrap() except that:

fn wrap<T>( &mut self, data: T, finalizer: impl FnOnce(NapiEnv, T) -> NapiResult<()>, ) -> NapiResult<NapiRef>

Wraps a native instance in a JavaScript object. The native instance can be retrieved later using napi_unwrap().

fn unwrap<T>(&self) -> NapiResult<Option<&mut T>>

Retrieves a native instance that was previously wrapped in a JavaScript object using napi_wrap().

fn remove_wrap<T>(&mut self) -> NapiResult<T>

Retrieves a native instance that was previously wrapped in the JavaScript object js_object using napi_wrap() and removes the wrapping. If a finalize callback was associated with the wrapping, it will no longer be called when the JavaScript object becomes garbage-collected.

fn type_tag_object(&self, tag: &NapiTypeTag) -> NapiResult<()>

Associates the value of the type_tag pointer with the JavaScript object. napi_check_object_type_tag() can then be used to compare the tag that was attached to the object with one owned by the addon to ensure that the object has the right type. If the object already has an associated type tag, this API will return napi_invalid_arg.

fn check_object_type_tag(&self, tag: &NapiTypeTag) -> NapiResult<bool>

Compares the pointer given as type_tag with any that can be found on js_object. If no tag is found on js_object or, if a tag is found but it does not match type_tag, then result is set to false. If a tag is found and it matches type_tag, then result is set to true.

impl<T: Copy> Copy for JsExternal<T>