Struct ScopedCx 

pub struct ScopedCx<'outer, 'inner> { /* private fields */ }

A temporary execution context created by Context::execute_scoped() or Context::compute_scoped().

ScopedCx carries two lifetimes:

• 'outer — the lifetime of the surrounding Context that created the temporary scope. Handles brought in from the outer scope (e.g. captured by the closure) carry this lifetime and remain valid for the entire enclosing computation.
• 'inner — the lifetime of this temporary scope. New handles allocated through this context carry 'inner and are released as soon as the scope ends. Because the closure passed to execute_scoped/compute_scoped is required to be valid for every choice of 'inner, the type system prevents an inner-scope handle from escaping into outer state through a captured &mut.

The implicit bound 'outer: 'inner carried by ScopedCx allows existing outer-scope handles to be used freely inside the temporary scope via the usual covariance of Handle.

Trait Implementations

impl<'outer, 'inner> Context<'inner> for ScopedCx<'outer, 'inner>

fn lock<'b>(&'b mut self) -> Lock<'b, Self>

where 'a: 'b,

Lock the JavaScript engine, returning an RAII guard that keeps the lock active as long as the guard is alive.

fn execute_scoped<T, F>(&mut self, f: F) -> T

where F: for<'b> FnOnce(ScopedCx<'a, 'b>) -> T,

Executes a computation in a new memory management scope.

fn compute_scoped<V, F>(&mut self, f: F) -> JsResult<'a, V>

where V: Value, F: for<'b> FnOnce(ScopedCx<'a, 'b>) -> JsResult<'b, V>,

Executes a computation in a new memory management scope and computes a single result value that outlives the computation.

fn try_catch<T, F>(&mut self, f: F) -> Result<T, Handle<'a, JsValue>>

where F: FnOnce(&mut Self) -> NeonResult<T>,

fn boolean(&mut self, b: bool) -> Handle<'a, JsBoolean>

Convenience method for creating a JsBoolean value.

fn number<T: Into<f64>>(&mut self, x: T) -> Handle<'a, JsNumber>

Convenience method for creating a JsNumber value.

fn string<S: AsRef<str>>(&mut self, s: S) -> Handle<'a, JsString>

Convenience method for creating a JsString value.

fn try_string<S: AsRef<str>>(&mut self, s: S) -> StringResult<'a>

Convenience method for creating a JsString value.

fn null(&mut self) -> Handle<'a, JsNull>

Convenience method for creating a JsNull value.

fn undefined(&mut self) -> Handle<'a, JsUndefined>

Convenience method for creating a JsUndefined value.

fn empty_object(&mut self) -> Handle<'a, JsObject>

Convenience method for creating an empty JsObject value.

fn empty_array(&mut self) -> Handle<'a, JsArray>

Convenience method for creating an empty JsArray value.

fn array_buffer(&mut self, size: usize) -> JsResult<'a, JsArrayBuffer>

Convenience method for creating an empty JsArrayBuffer value.

fn buffer(&mut self, size: usize) -> JsResult<'a, JsBuffer>

Convenience method for creating an empty JsBuffer value.

fn date( &mut self, value: impl Into<f64>, ) -> Result<Handle<'a, JsDate>, DateError>

Available on crate feature napi-5 only.

Convenience method for creating a JsDate value.

fn global<T: Value>(&mut self, name: &str) -> JsResult<'a, T>

Convenience method for looking up a global property by name.

fn global_object(&mut self) -> Handle<'a, JsObject>

Produces a handle to the JavaScript global object.

fn throw<T: Value, U>(&mut self, v: Handle<'_, T>) -> NeonResult<U>

Throws a JS value.

fn error<S: AsRef<str>>(&mut self, msg: S) -> JsResult<'a, JsError>

Creates a direct instance of the Error class.

fn type_error<S: AsRef<str>>(&mut self, msg: S) -> JsResult<'a, JsError>

Creates an instance of the TypeError class.

fn range_error<S: AsRef<str>>(&mut self, msg: S) -> JsResult<'a, JsError>

Creates an instance of the RangeError class.

fn throw_error<S: AsRef<str>, T>(&mut self, msg: S) -> NeonResult<T>

Throws a direct instance of the Error class.

fn throw_type_error<S: AsRef<str>, T>(&mut self, msg: S) -> NeonResult<T>

Throws an instance of the TypeError class.

fn throw_range_error<S: AsRef<str>, T>(&mut self, msg: S) -> NeonResult<T>

Throws an instance of the RangeError class.

fn boxed<U: Finalize + 'static>(&mut self, v: U) -> Handle<'a, JsBox<U>>

Convenience method for wrapping a value in a JsBox.

fn channel(&mut self) -> Channel

Available on crate feature napi-4 only.

Returns an unbounded channel for scheduling events to be executed on the JavaScript thread.

fn promise(&mut self) -> (Deferred, Handle<'a, JsPromise>)

Creates a Deferred and JsPromise pair. The Deferred handle can be used to resolve or reject the JsPromise.

fn task<'cx, O, E>(&'cx mut self, execute: E) -> TaskBuilder<'cx, Self, E>

where O: Send + 'static, E: FnOnce() -> O + Send + 'static, 'a: 'cx,

Creates a TaskBuilder which can be used to schedule the execute callback to asynchronously execute on the Node worker pool.

fn to_raw(&self) -> Env

Available on crate feature sys only.

Gets the raw sys::Env for usage with Node-API.

impl<'outer, 'inner> Deref for ScopedCx<'outer, 'inner>

type Target = Cx<'inner>

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl<'outer, 'inner> DerefMut for ScopedCx<'outer, 'inner>

fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.