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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 http://mozilla.org/MPL/2.0/. */
#ifndef mozilla_dom_PromiseNativeHandler_h
#define mozilla_dom_PromiseNativeHandler_h
#include <functional>
#include "js/TypeDecls.h"
#include "js/Value.h"
#include "mozilla/ErrorResult.h"
#include "mozilla/Maybe.h"
#include "nsISupports.h"
namespace mozilla::dom {
/*
* PromiseNativeHandler allows C++ to react to a Promise being
* rejected/resolved. A PromiseNativeHandler can be appended to a Promise using
* Promise::AppendNativeHandler().
*/
class PromiseNativeHandler : public nsISupports {
protected:
virtual ~PromiseNativeHandler() = default;
public:
MOZ_CAN_RUN_SCRIPT
virtual void ResolvedCallback(JSContext* aCx, JS::Handle<JS::Value> aValue,
ErrorResult& aRv) = 0;
MOZ_CAN_RUN_SCRIPT
virtual void RejectedCallback(JSContext* aCx, JS::Handle<JS::Value> aValue,
ErrorResult& aRv) = 0;
};
// This base class exists solely to use NS_IMPL_ISUPPORTS because it doesn't
// support template classes.
class MozPromiseRejectOnDestructionBase : public PromiseNativeHandler {
NS_DECL_ISUPPORTS
void ResolvedCallback(JSContext* aCx, JS::Handle<JS::Value> aValue,
ErrorResult& aRv) override {}
void RejectedCallback(JSContext* aCx, JS::Handle<JS::Value> aValue,
ErrorResult& aRv) override {}
protected:
~MozPromiseRejectOnDestructionBase() override = default;
};
// Use this when you subscribe to a JS promise to settle a MozPromise that is
// not guaranteed to be settled by anyone else.
template <typename T>
class MozPromiseRejectOnDestruction final
: public MozPromiseRejectOnDestructionBase {
public:
// (Accepting RefPtr<T> instead of T* because compiler fails to implicitly
// convert it at call sites)
MozPromiseRejectOnDestruction(const RefPtr<T>& aMozPromise,
const char* aCallSite)
: mMozPromise(aMozPromise), mCallSite(aCallSite) {
MOZ_ASSERT(aMozPromise);
}
protected:
~MozPromiseRejectOnDestruction() override {
// Rejecting will be no-op if the promise is already settled
mMozPromise->Reject(NS_BINDING_ABORTED, mCallSite);
}
RefPtr<T> mMozPromise;
const char* mCallSite;
};
} // namespace mozilla::dom
#endif // mozilla_dom_PromiseNativeHandler_h
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