gecko-dev/dom/promise/PromiseCallback.cpp

/* -*- Mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; tab-width: 40 -*- */
/* vim: set ts=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/. */

#include "PromiseCallback.h"
#include "mozilla/dom/Promise.h"
#include "mozilla/dom/PromiseNativeHandler.h"

#include "js/OldDebugAPI.h"

namespace mozilla {
namespace dom {

NS_IMPL_CYCLE_COLLECTING_ADDREF(PromiseCallback)
NS_IMPL_CYCLE_COLLECTING_RELEASE(PromiseCallback)

NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(PromiseCallback)
  NS_INTERFACE_MAP_ENTRY(nsISupports)
NS_INTERFACE_MAP_END

NS_IMPL_CYCLE_COLLECTION_CLASS(PromiseCallback)

NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(PromiseCallback)
NS_IMPL_CYCLE_COLLECTION_UNLINK_END

NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(PromiseCallback)
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END

PromiseCallback::PromiseCallback()
{
  MOZ_COUNT_CTOR(PromiseCallback);
}

PromiseCallback::~PromiseCallback()
{
  MOZ_COUNT_DTOR(PromiseCallback);
}

static void
EnterCompartment(Maybe<JSAutoCompartment>& aAc, JSContext* aCx,
                 JS::Handle<JS::Value> aValue)
{
  // FIXME Bug 878849
  if (aValue.isObject()) {
    JS::Rooted<JSObject*> rooted(aCx, &aValue.toObject());
    aAc.construct(aCx, rooted);
  }
}

// ResolvePromiseCallback

NS_IMPL_CYCLE_COLLECTION_INHERITED_1(ResolvePromiseCallback,
                                     PromiseCallback,
                                     mPromise)

NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION_INHERITED(ResolvePromiseCallback)
NS_INTERFACE_MAP_END_INHERITING(PromiseCallback)

NS_IMPL_ADDREF_INHERITED(ResolvePromiseCallback, PromiseCallback)
NS_IMPL_RELEASE_INHERITED(ResolvePromiseCallback, PromiseCallback)

ResolvePromiseCallback::ResolvePromiseCallback(Promise* aPromise)
  : mPromise(aPromise)
{
  MOZ_ASSERT(aPromise);
  MOZ_COUNT_CTOR(ResolvePromiseCallback);
}

ResolvePromiseCallback::~ResolvePromiseCallback()
{
  MOZ_COUNT_DTOR(ResolvePromiseCallback);
}

void
ResolvePromiseCallback::Call(JS::Handle<JS::Value> aValue)
{
  // Run resolver's algorithm with value and the synchronous flag set.
  ThreadsafeAutoSafeJSContext cx;

  Maybe<JSAutoCompartment> ac;
  EnterCompartment(ac, cx, aValue);

  mPromise->ResolveInternal(cx, aValue, Promise::SyncTask);
}

// RejectPromiseCallback

NS_IMPL_CYCLE_COLLECTION_INHERITED_1(RejectPromiseCallback,
                                     PromiseCallback,
                                     mPromise)

NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION_INHERITED(RejectPromiseCallback)
NS_INTERFACE_MAP_END_INHERITING(PromiseCallback)

NS_IMPL_ADDREF_INHERITED(RejectPromiseCallback, PromiseCallback)
NS_IMPL_RELEASE_INHERITED(RejectPromiseCallback, PromiseCallback)

RejectPromiseCallback::RejectPromiseCallback(Promise* aPromise)
  : mPromise(aPromise)
{
  MOZ_ASSERT(aPromise);
  MOZ_COUNT_CTOR(RejectPromiseCallback);
}

RejectPromiseCallback::~RejectPromiseCallback()
{
  MOZ_COUNT_DTOR(RejectPromiseCallback);
}

void
RejectPromiseCallback::Call(JS::Handle<JS::Value> aValue)
{
  // Run resolver's algorithm with value and the synchronous flag set.
  ThreadsafeAutoSafeJSContext cx;

  Maybe<JSAutoCompartment> ac;
  EnterCompartment(ac, cx, aValue);

  mPromise->RejectInternal(cx, aValue, Promise::SyncTask);
}

// WrapperPromiseCallback

NS_IMPL_CYCLE_COLLECTION_INHERITED_2(WrapperPromiseCallback,
                                     PromiseCallback,
                                     mNextPromise, mCallback)

NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION_INHERITED(WrapperPromiseCallback)
NS_INTERFACE_MAP_END_INHERITING(PromiseCallback)

NS_IMPL_ADDREF_INHERITED(WrapperPromiseCallback, PromiseCallback)
NS_IMPL_RELEASE_INHERITED(WrapperPromiseCallback, PromiseCallback)

WrapperPromiseCallback::WrapperPromiseCallback(Promise* aNextPromise,
                                               AnyCallback* aCallback)
  : mNextPromise(aNextPromise)
  , mCallback(aCallback)
{
  MOZ_ASSERT(aNextPromise);
  MOZ_COUNT_CTOR(WrapperPromiseCallback);
}

WrapperPromiseCallback::~WrapperPromiseCallback()
{
  MOZ_COUNT_DTOR(WrapperPromiseCallback);
}

void
WrapperPromiseCallback::Call(JS::Handle<JS::Value> aValue)
{
  ThreadsafeAutoSafeJSContext cx;

  Maybe<JSAutoCompartment> ac;
  EnterCompartment(ac, cx, aValue);

  ErrorResult rv;

  // If invoking callback threw an exception, run resolver's reject with the
  // thrown exception as argument and the synchronous flag set.
  JS::Rooted<JS::Value> value(cx,
    mCallback->Call(aValue, rv, CallbackObject::eRethrowExceptions));

  rv.WouldReportJSException();

  if (rv.Failed() && rv.IsJSException()) {
    JS::Rooted<JS::Value> value(cx);
    rv.StealJSException(cx, &value);

    Maybe<JSAutoCompartment> ac2;
    EnterCompartment(ac2, cx, value);
    mNextPromise->RejectInternal(cx, value, Promise::SyncTask);
    return;
  }

  // If the return value is the same as the promise itself, throw TypeError.
  if (value.isObject()) {
    JS::Rooted<JSObject*> valueObj(cx, &value.toObject());
    Promise* returnedPromise;
    nsresult r = UNWRAP_OBJECT(Promise, valueObj, returnedPromise);

    if (NS_SUCCEEDED(r) && returnedPromise == mNextPromise) {
      const char* fileName = nullptr;
      uint32_t lineNumber = 0;

      // Try to get some information about the callback to report a sane error,
      // but don't try too hard (only deals with scripted functions).
      JS::Rooted<JSObject*> unwrapped(cx,
        js::CheckedUnwrap(mCallback->Callback()));

      if (unwrapped) {
        JSAutoCompartment ac(cx, unwrapped);
        if (JS_ObjectIsFunction(cx, unwrapped)) {
          JS::Rooted<JS::Value> asValue(cx, JS::ObjectValue(*unwrapped));
          JS::Rooted<JSFunction*> func(cx, JS_ValueToFunction(cx, asValue));

          MOZ_ASSERT(func);
          JSScript* script = JS_GetFunctionScript(cx, func);
          if (script) {
            fileName = JS_GetScriptFilename(script);
            lineNumber = JS_GetScriptBaseLineNumber(cx, script);
          }
        }
      }

      // We're back in aValue's compartment here.
      JS::Rooted<JSString*> stack(cx, JS_GetEmptyString(JS_GetRuntime(cx)));
      JS::Rooted<JSString*> fn(cx, JS_NewStringCopyZ(cx, fileName));
      if (!fn) {
        // Out of memory. Promise will stay unresolved.
        JS_ClearPendingException(cx);
        return;
      }

      JS::Rooted<JSString*> message(cx,
        JS_NewStringCopyZ(cx,
          "then() cannot return same Promise that it resolves."));
      if (!message) {
        // Out of memory. Promise will stay unresolved.
        JS_ClearPendingException(cx);
        return;
      }

      JS::Rooted<JS::Value> typeError(cx);
      if (!JS::CreateTypeError(cx, stack, fn, lineNumber, 0,
                               nullptr, message, &typeError)) {
        // Out of memory. Promise will stay unresolved.
        JS_ClearPendingException(cx);
        return;
      }

      mNextPromise->RejectInternal(cx, typeError, Promise::SyncTask);
      return;
    }
  }

  // Otherwise, run resolver's resolve with value and the synchronous flag
  // set.
  Maybe<JSAutoCompartment> ac2;
  EnterCompartment(ac2, cx, value);
  mNextPromise->ResolveInternal(cx, value, Promise::SyncTask);
}

// NativePromiseCallback

NS_IMPL_CYCLE_COLLECTION_INHERITED_1(NativePromiseCallback,
                                     PromiseCallback, mHandler)

NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION_INHERITED(NativePromiseCallback)
NS_INTERFACE_MAP_END_INHERITING(PromiseCallback)

NS_IMPL_ADDREF_INHERITED(NativePromiseCallback, PromiseCallback)
NS_IMPL_RELEASE_INHERITED(NativePromiseCallback, PromiseCallback)

NativePromiseCallback::NativePromiseCallback(PromiseNativeHandler* aHandler,
                                             Promise::PromiseState aState)
  : mHandler(aHandler)
  , mState(aState)
{
  MOZ_ASSERT(aHandler);
  MOZ_COUNT_CTOR(NativePromiseCallback);
}

NativePromiseCallback::~NativePromiseCallback()
{
  MOZ_COUNT_DTOR(NativePromiseCallback);
}

void
NativePromiseCallback::Call(JS::Handle<JS::Value> aValue)
{
  if (mState == Promise::Resolved) {
    mHandler->ResolvedCallback(aValue);
    return;
  }

  if (mState == Promise::Rejected) {
    mHandler->RejectedCallback(aValue);
    return;
  }

  NS_NOTREACHED("huh?");
}

/* static */ PromiseCallback*
PromiseCallback::Factory(Promise* aNextPromise, AnyCallback* aCallback,
                         Task aTask)
{
  MOZ_ASSERT(aNextPromise);

  // If we have a callback and a next resolver, we have to exec the callback and
  // then propagate the return value to the next resolver->resolve().
  if (aCallback) {
    return new WrapperPromiseCallback(aNextPromise, aCallback);
  }

  if (aTask == Resolve) {
    return new ResolvePromiseCallback(aNextPromise);
  }

  if (aTask == Reject) {
    return new RejectPromiseCallback(aNextPromise);
  }

  MOZ_ASSERT(false, "This should not happen");
  return nullptr;
}

} // namespace dom
} // namespace mozilla