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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=8 sts=2 et sw=2 tw=80:
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at */
#ifndef builtin_Promise_h
#define builtin_Promise_h
#include "js/Promise.h"
#include "jstypes.h" // JS_PUBLIC_API
#include "js/CallArgs.h" // JS::CallArgs
#include "js/RootingAPI.h" // JS::{,Mutable}Handle
#include "js/TypeDecls.h" // JS::HandleObjectVector
#include "js/Value.h" // JS::Value
struct JS_PUBLIC_API JSContext;
class JS_PUBLIC_API JSObject;
namespace js {
class AsyncFunctionGeneratorObject;
class AsyncGeneratorObject;
class PromiseObject;
class SavedFrame;
enum class CompletionKind;
enum class PromiseHandler : uint32_t {
Identity = 0,
// ES2022 draft rev d03c1ec6e235a5180fa772b6178727c17974cb14
// Await in async function
// Step 3. fulfilledClosure Abstract Closure.
// Step 5. rejectedClosure Abstract Closure.
// Await in async generator
// Step 3. fulfilledClosure Abstract Closure.
// Step 5. rejectedClosure Abstract Closure.
// AsyncGeneratorAwaitReturn ( generator )
// Step 7. fulfilledClosure Abstract Closure.
// Step 9. rejectedClosure Abstract Closure.
// AsyncGeneratorUnwrapYieldResumption
// Steps 3-5 for awaited.[[Type]] handling.
// AsyncFromSyncIteratorContinuation ( result, promiseCapability )
// Steps 7. unwrap Abstract Closure.
// One past the maximum allowed PromiseHandler value.
// Promise.prototype.then.
extern bool Promise_then(JSContext* cx, unsigned argc, JS::Value* vp);
// Promise[Symbol.species].
extern bool Promise_static_species(JSContext* cx, unsigned argc, JS::Value* vp);
// Promise.resolve.
extern bool Promise_static_resolve(JSContext* cx, unsigned argc, JS::Value* vp);
* Unforgeable version of the JS builtin Promise.all.
* Takes a HandleValueVector of Promise objects and returns a promise that's
* resolved with an array of resolution values when all those promises have
* been resolved, or rejected with the rejection value of the first rejected
* promise.
* Asserts that all objects in the `promises` vector are, maybe wrapped,
* instances of `Promise` or a subclass of `Promise`.
[[nodiscard]] JSObject* GetWaitForAllPromise(JSContext* cx,
JS::HandleObjectVector promises);
* Enqueues resolve/reject reactions in the given Promise's reactions lists
* as though by calling the original value of Promise.prototype.then, and
* without regard to any Promise subclassing used in `promiseObj` itself.
[[nodiscard]] PromiseObject* OriginalPromiseThen(
JSContext* cx, JS::Handle<JSObject*> promiseObj,
JS::Handle<JSObject*> onFulfilled, JS::Handle<JSObject*> onRejected);
enum class UnhandledRejectionBehavior { Ignore, Report };
* React to[0] `unwrappedPromise` (which may not be from the current realm) as
* if by using a fresh promise created for the provided nullable fulfill/reject
* IsCallable objects.
* However, no dependent Promise will be created, and mucking with `Promise`,
* `Promise.prototype.then`, and `Promise[Symbol.species]` will not alter this
* function's behavior.
* If `unwrappedPromise` rejects and `onRejected_` is null, handling is
* determined by `behavior`. If `behavior == Report`, a fresh Promise will be
* constructed and rejected on the fly (and thus will be reported as unhandled).
* But if `behavior == Ignore`, the rejection is ignored and is not reported as
* unhandled.
* Note: Reactions pushed using this function contain a null `promise` field.
* That field is only ever used by devtools, which have to treat these reactions
* specially.
* 0. The sense of "react" here is the sense of the term as defined by Web IDL:
[[nodiscard]] extern bool ReactToUnwrappedPromise(
JSContext* cx, JS::Handle<PromiseObject*> unwrappedPromise,
JS::Handle<JSObject*> onFulfilled_, JS::Handle<JSObject*> onRejected_,
UnhandledRejectionBehavior behavior);
* PromiseResolve ( C, x )
* The abstract operation PromiseResolve, given a constructor and a value,
* returns a new promise resolved with that value.
[[nodiscard]] JSObject* PromiseResolve(JSContext* cx,
JS::Handle<JSObject*> constructor,
JS::Handle<JS::Value> value);
* Reject |promise| with the value of the current pending exception.
* |promise| must be from the current realm. Callers must enter the realm of
* |promise| if they are not already in it.
[[nodiscard]] bool RejectPromiseWithPendingError(
JSContext* cx, JS::Handle<PromiseObject*> promise);
* Create the promise object which will be used as the return value of an async
* function.
[[nodiscard]] PromiseObject* CreatePromiseObjectForAsync(JSContext* cx);
* Returns true if the given object is a promise created by
* either CreatePromiseObjectForAsync function or async generator's method.
[[nodiscard]] bool IsPromiseForAsyncFunctionOrGenerator(JSObject* promise);
[[nodiscard]] bool AsyncFunctionReturned(
JSContext* cx, JS::Handle<PromiseObject*> resultPromise,
JS::Handle<JS::Value> value);
[[nodiscard]] bool AsyncFunctionThrown(JSContext* cx,
JS::Handle<PromiseObject*> resultPromise,
JS::Handle<JS::Value> reason);
// Start awaiting `value` in an async function (, but doesn't suspend the
// async function's execution!). Returns the async function's result promise.
[[nodiscard]] JSObject* AsyncFunctionAwait(
JSContext* cx, JS::Handle<AsyncFunctionGeneratorObject*> genObj,
JS::Handle<JS::Value> value);
// If the await operation can be skipped and the resolution value for `val` can
// be acquired, stored the resolved value to `resolved` and `true` to
// `*canSkip`. Otherwise, stores `false` to `*canSkip`.
[[nodiscard]] bool CanSkipAwait(JSContext* cx, JS::Handle<JS::Value> val,
bool* canSkip);
[[nodiscard]] bool ExtractAwaitValue(JSContext* cx, JS::Handle<JS::Value> val,
JS::MutableHandle<JS::Value> resolved);
bool AsyncFromSyncIteratorMethod(JSContext* cx, JS::CallArgs& args,
CompletionKind completionKind);
// Callback for describing promise reaction records, for use with
// PromiseObject::getReactionRecords.
struct PromiseReactionRecordBuilder {
// A reaction record created by a call to 'then' or 'catch', with functions to
// call on resolution or rejection, and the promise that will be settled
// according to the result of calling them.
// Note that resolve, reject, and result may not be same-compartment with cx,
// or with the promise we're inspecting. This function presents the values
// exactly as they appear in the reaction record. They may also be wrapped or
// unwrapped.
// Some reaction records refer to internal resolution or rejection functions
// that are not naturally represented as debuggee JavaScript functions. In
// this case, resolve and reject may be nullptr.
[[nodiscard]] virtual bool then(JSContext* cx, JS::Handle<JSObject*> resolve,
JS::Handle<JSObject*> reject,
JS::Handle<JSObject*> result) = 0;
// A reaction record created when one native promise is resolved to another.
// The 'promise' argument is the promise that will be settled in the same way
// the promise this reaction record is attached to is settled.
// Note that promise may not be same-compartment with cx. This function
// presents the promise exactly as it appears in the reaction record.
[[nodiscard]] virtual bool direct(
JSContext* cx, JS::Handle<PromiseObject*> unwrappedPromise) = 0;
// A reaction record that resumes an asynchronous function suspended at an
// await expression. The 'generator' argument is the generator object
// representing the call.
// Note that generator may not be same-compartment with cx. This function
// presents the generator exactly as it appears in the reaction record.
[[nodiscard]] virtual bool asyncFunction(
JSContext* cx,
JS::Handle<AsyncFunctionGeneratorObject*> unwrappedGenerator) = 0;
// A reaction record that resumes an asynchronous generator suspended at an
// await expression. The 'generator' argument is the generator object
// representing the call.
// Note that generator may not be same-compartment with cx. This function
// presents the generator exactly as it appears in the reaction record.
[[nodiscard]] virtual bool asyncGenerator(
JSContext* cx, JS::Handle<AsyncGeneratorObject*> unwrappedGenerator) = 0;
[[nodiscard]] PromiseObject* CreatePromiseObjectForAsyncGenerator(
JSContext* cx);
[[nodiscard]] bool ResolvePromiseInternal(JSContext* cx,
JS::Handle<JSObject*> promise,
JS::Handle<JS::Value> resolutionVal);
[[nodiscard]] bool RejectPromiseInternal(
JSContext* cx, JS::Handle<PromiseObject*> promise,
JS::Handle<JS::Value> reason,
JS::Handle<SavedFrame*> unwrappedRejectionStack = nullptr);
[[nodiscard]] bool InternalAsyncGeneratorAwait(
JSContext* cx, JS::Handle<AsyncGeneratorObject*> generator,
JS::Handle<JS::Value> value, PromiseHandler onFulfilled,
PromiseHandler onRejected);
} // namespace js
#endif // builtin_Promise_h