Struct PromiseCapability 

pub struct PromiseCapability<'a> { /* private fields */ }

A promise capability encapsulates a promise, adding methods that are capable of resolving or rejecting that promise.

NOTE: In the spec, promise capability records contain an object that is usable as a promise, together with its resolve and reject functions. In our current implementation, we only ever support built-in promises, and not other promise-like objects (e.g. we don’t support Promise subclasses), and for that we don’t need to store resolve and reject functions, we can create them only when needed.

The must_be_unresolved boolean is used to map the AlreadyResolved state of a pair of resolve/reject functions with the promise state. If must_be_unresolved is false, the promise counts as already resolved if its state is Fulfilled or Rejected. If true, it also counts as already resolved if it’s Pending but is_resolved is set to true.

Implementations

impl<'a> PromiseCapability<'a>

pub fn new(agent: &mut Agent, gc: NoGcScope<'a, '_>) -> Self

27.2.1.5 NewPromiseCapability ( C )

Create a new PromiseCapability

NOTE: Our implementation doesn’t take C as a parameter, since we don’t yet support promise subclassing.

pub fn from_promise(promise: Promise<'a>, must_be_unresolved: bool) -> Self

Recreate a PromiseCapability from its associated Promise and the must_be_resolved boolean value.

pub fn promise(&self) -> Promise<'a>

Get the associated Promise.

pub fn resolve( self, agent: &mut Agent, resolution: Value<'_>, gc: GcScope<'_, '_>, )

27.2.1.3.2 Promise Resolve Functions

Resolve the associated Promise with a given value. Ignored if the Promise is already resolved.

pub fn try_resolve<'gc>( &self, agent: &mut Agent, resolution: Value<'_>, gc: NoGcScope<'gc, '_>, ) -> TryResult<'gc, ()>

27.2.1.3.2 Promise Resolve Functions

Try resolve the associated Promise with a given value. Fails if resolving would require calling into user-code. Ignored if the Promise is already resolved.

pub fn reject( &self, agent: &mut Agent, reason: Value<'_>, gc: NoGcScope<'_, '_>, )

27.2.1.3.1 Promise Reject Functions

Reject the associated Promise with a given value. Ignored if the Promise is already resolved.

Trait Implementations

impl Bindable for PromiseCapability<'_>

type Of<'a> = PromiseCapability<'a>

Bound representation of self. This must always be effectively equal to Self<'a>. Note that we cannot write Self<'a> directly because Self cannot have lifetime parameters attached to it.

fn unbind(self) -> Self::Of<'static>

Unbind this value from the garbage collector lifetime. This is necessary for eg. when using the value as a parameter in a call that can perform garbage collection.

fn bind<'a>(self, _: NoGcScope<'a, '_>) -> Self::Of<'a>

Bind this value to the garbage collector lifetime. This is necessary to enable the borrow checker to check that bindable values are not use-after-free.

impl<'a> Clone for PromiseCapability<'a>

fn clone(&self) -> PromiseCapability<'a>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<'a> Debug for PromiseCapability<'a>

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

Formats the value using the given formatter.

impl<'a> Eq for PromiseCapability<'a>

impl<'a> Ord for PromiseCapability<'a>

fn cmp(&self, other: &PromiseCapability<'a>) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl<'a> PartialEq for PromiseCapability<'a>

fn eq(&self, other: &PromiseCapability<'a>) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<'a> PartialOrd for PromiseCapability<'a>

fn partial_cmp(&self, other: &PromiseCapability<'a>) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl<'a> StructuralPartialEq for PromiseCapability<'a>