dom/promise/Promise.h
author Csoregi Natalia <ncsoregi@mozilla.com>
Thu, 01 Mar 2018 16:29:02 +0200
changeset 458530 a416b0a21b1395dfe7dc28577a31be57c075d9b4
parent 458470 55c94c05c57f0bb34ca131c68c79e05a97aa4b6c
child 459020 068c59c7c4ec46802b4a18e98adc227aed6d5da1
permissions -rw-r--r--
Backed out 7 changesets (bug 1193394) for browser-chrome failures on browser_ext_popup_background.js. CLOSED TREE Backed out changeset 9683f24ff8ec (bug 1193394) Backed out changeset 0e7140a7c841 (bug 1193394) Backed out changeset a0e26f6b2784 (bug 1193394) Backed out changeset 29e1fceaf48d (bug 1193394) Backed out changeset b8632bbbd273 (bug 1193394) Backed out changeset a54ef2d8f896 (bug 1193394) Backed out changeset 55c94c05c57f (bug 1193394)

/* -*- 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_Promise_h
#define mozilla_dom_Promise_h

#include "mozilla/Attributes.h"
#include "mozilla/ErrorResult.h"
#include "mozilla/TimeStamp.h"
#include "mozilla/TypeTraits.h"
#include "mozilla/dom/BindingDeclarations.h"
#include "nsCycleCollectionParticipant.h"
#include "mozilla/dom/PromiseBinding.h"
#include "mozilla/dom/ToJSValue.h"
#include "mozilla/WeakPtr.h"
#include "nsWrapperCache.h"
#include "nsAutoPtr.h"
#include "js/TypeDecls.h"
#include "jspubtd.h"

class nsIGlobalObject;

namespace mozilla {
namespace dom {

class AnyCallback;
class MediaStreamError;
class PromiseInit;
class PromiseNativeHandler;
class PromiseDebugging;

#define NS_PROMISE_IID \
  { 0x1b8d6215, 0x3e67, 0x43ba, \
    { 0x8a, 0xf9, 0x31, 0x5e, 0x8f, 0xce, 0x75, 0x65 } }

class Promise : public nsISupports,
                public SupportsWeakPtr<Promise>
{
  friend class PromiseTask;
  friend class PromiseWorkerProxy;
  friend class PromiseWorkerProxyRunnable;

public:
  NS_DECLARE_STATIC_IID_ACCESSOR(NS_PROMISE_IID)
  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(Promise)
  MOZ_DECLARE_WEAKREFERENCE_TYPENAME(Promise)

  // Promise creation tries to create a JS reflector for the Promise, so is
  // fallible.  Furthermore, we don't want to do JS-wrapping on a 0-refcount
  // object, so we addref before doing that and return the addrefed pointer
  // here.
  static already_AddRefed<Promise>
  Create(nsIGlobalObject* aGlobal, ErrorResult& aRv);

  // Reports a rejected Promise by sending an error report.
  static void ReportRejectedPromise(JSContext* aCx, JS::HandleObject aPromise);

  typedef void (Promise::*MaybeFunc)(JSContext* aCx,
                                     JS::Handle<JS::Value> aValue);

  void MaybeResolve(JSContext* aCx,
                    JS::Handle<JS::Value> aValue);
  void MaybeReject(JSContext* aCx,
                   JS::Handle<JS::Value> aValue);

  // Helpers for using Promise from C++.
  // Most DOM objects are handled already.  To add a new type T, add a
  // ToJSValue overload in ToJSValue.h.
  // aArg is a const reference so we can pass rvalues like integer constants
  template <typename T>
  void MaybeResolve(const T& aArg) {
    MaybeSomething(aArg, &Promise::MaybeResolve);
  }

  void MaybeResolveWithUndefined();

  inline void MaybeReject(nsresult aArg) {
    MOZ_ASSERT(NS_FAILED(aArg));
    MaybeSomething(aArg, &Promise::MaybeReject);
  }

  inline void MaybeReject(ErrorResult& aArg) {
    MOZ_ASSERT(aArg.Failed());
    MaybeSomething(aArg, &Promise::MaybeReject);
  }

  void MaybeReject(const RefPtr<MediaStreamError>& aArg);

  void MaybeRejectWithUndefined();

  // DO NOT USE MaybeRejectBrokenly with in new code.  Promises should be
  // rejected with Error instances.
  // Note: MaybeRejectBrokenly is a template so we can use it with DOMException
  // without instantiating the DOMException specialization of MaybeSomething in
  // every translation unit that includes this header, because that would
  // require use to include DOMException.h either here or in all those
  // translation units.
  template<typename T>
  void MaybeRejectBrokenly(const T& aArg); // Not implemented by default; see
                                           // specializations in the .cpp for
                                           // the T values we support.

  // Called by DOM to let us execute our callbacks.  May be called recursively.
  // Returns true if at least one microtask was processed.
  static bool PerformMicroTaskCheckpoint();

  static void PerformWorkerMicroTaskCheckpoint();

  static void PerformWorkerDebuggerMicroTaskCheckpoint();
  static bool IsWorkerDebuggerMicroTaskEmpty();

  // WebIDL

  nsIGlobalObject* GetParentObject() const
  {
    return mGlobal;
  }

  // Do the equivalent of Promise.resolve in the current compartment of aCx.
  // Errorrs are reported on the ErrorResult; if aRv comes back !Failed(), this
  // function MUST return a non-null value.
  static already_AddRefed<Promise>
  Resolve(nsIGlobalObject* aGlobal, JSContext* aCx,
          JS::Handle<JS::Value> aValue, ErrorResult& aRv);

  // Do the equivalent of Promise.reject in the current compartment of aCx.
  // Errorrs are reported on the ErrorResult; if aRv comes back !Failed(), this
  // function MUST return a non-null value.
  static already_AddRefed<Promise>
  Reject(nsIGlobalObject* aGlobal, JSContext* aCx,
         JS::Handle<JS::Value> aValue, ErrorResult& aRv);

  static already_AddRefed<Promise>
  All(const GlobalObject& aGlobal,
      const nsTArray<RefPtr<Promise>>& aPromiseList, ErrorResult& aRv);

  void
  Then(JSContext* aCx,
       // aCalleeGlobal may not be in the compartment of aCx, when called over
       // Xrays.
       JS::Handle<JSObject*> aCalleeGlobal,
       AnyCallback* aResolveCallback, AnyCallback* aRejectCallback,
       JS::MutableHandle<JS::Value> aRetval,
       ErrorResult& aRv);

  JSObject* PromiseObj() const
  {
    return mPromiseObj;
  }

  void AppendNativeHandler(PromiseNativeHandler* aRunnable);

  JSObject* GlobalJSObject() const;

  JSCompartment* Compartment() const;

  // Create a dom::Promise from a given SpiderMonkey Promise object.
  // aPromiseObj MUST be in the compartment of aGlobal's global JS object.
  static already_AddRefed<Promise>
  CreateFromExisting(nsIGlobalObject* aGlobal,
                     JS::Handle<JSObject*> aPromiseObj);

  enum class PromiseState {
    Pending,
    Resolved,
    Rejected
  };

  PromiseState State() const;

protected:
  struct PromiseCapability;

  // Do NOT call this unless you're Promise::Create or
  // Promise::CreateFromExisting.  I wish we could enforce that from inside this
  // class too, somehow.
  explicit Promise(nsIGlobalObject* aGlobal);

  virtual ~Promise();

  // Do JS-wrapping after Promise creation.  Passing null for aDesiredProto will
  // use the default prototype for the sort of Promise we have.
  void CreateWrapper(JS::Handle<JSObject*> aDesiredProto, ErrorResult& aRv);

private:
  template <typename T>
  void MaybeSomething(T& aArgument, MaybeFunc aFunc) {
    MOZ_ASSERT(PromiseObj()); // It was preserved!

    AutoEntryScript aes(mGlobal, "Promise resolution or rejection");
    JSContext* cx = aes.cx();

    JS::Rooted<JS::Value> val(cx);
    if (!ToJSValue(cx, aArgument, &val)) {
      HandleException(cx);
      return;
    }

    (this->*aFunc)(cx, val);
  }

  void HandleException(JSContext* aCx);

  RefPtr<nsIGlobalObject> mGlobal;

  JS::Heap<JSObject*> mPromiseObj;
};

NS_DEFINE_STATIC_IID_ACCESSOR(Promise, NS_PROMISE_IID)

} // namespace dom
} // namespace mozilla

#endif // mozilla_dom_Promise_h