915368 - Give dictionaries a copy constructor and operator= when it's safe

Status: RESOLVED FIXED

(Core :: DOM: Core & HTML, defect)

Description

[Boris Zbarsky [:bzbarsky]]

Specifically, if we contain only strings, enums, primitives, sequences containing safe stuff, dictionaries with only safe members, nullables around any of that.

Comment 1

[Boris Zbarsky [:bzbarsky]]

So for this IDL:

dictionary ParentTest {
  boolean haha;
};
dictionary MediaTrackConstraintSet : ParentTest {
    VideoFacingModeEnum facingMode;
};
dictionary MediaStreamConstraintsInternal {
    boolean fake = false;
    MediaTrackConstraintsInternal audiom;
};
dictionary MediaTrackConstraintsInternal {
    MediaTrackConstraintSet mandatory;
    sequence<MediaTrackConstraintSet> _optional;
};

we get codegen like so in the header:

  explicit inline ParentTest(const ParentTest& aOther)
  {
    *this = aOther;
  }
  void
  operator=(const ParentTest& aOther);

and likewise for the other dictionaries, and like so in the .cpp:

  void
  ParentTest::operator=(const ParentTest& aOther)
  {
    if (aOther.mHaha.WasPassed()) {
      mHaha.Construct();
      mHaha.Value() = aOther.mHaha.Value();
    } else {
      mHaha.Reset();
    }
  }

  void
  MediaTrackConstraintSet::operator=(const MediaTrackConstraintSet& aOther)
  {
    ParentTest::operator=(aOther);
    if (aOther.mFacingMode.WasPassed()) {
      mFacingMode.Construct();
      mFacingMode.Value() = aOther.mFacingMode.Value();
    } else {
      mFacingMode.Reset();
    }
  }

  void
  MediaTrackConstraintsInternal::operator=(const MediaTrackConstraintsInternal& aOther)
  {
    mMandatory = aOther.mMandatory;
    if (aOther.mOptional.WasPassed()) {
      mOptional.Construct();
      mOptional.Value() = aOther.mOptional.Value();
    } else {
      mOptional.Reset();
    }
  }

  void
  MediaStreamConstraintsInternal::operator=(const MediaStreamConstraintsInternal& aOther)
  {
    mAudiom = aOther.mAudiom;
    mFake = aOther.mFake;
  }

Comment 2

[Boris Zbarsky [:bzbarsky]]

Attachment: Give dictionaries copy constructors and assignment operators when it's safe.

Comment 3

[Jan-Ivar Bruaroey [:jib] (needinfo? me)]

Thanks for the patch! - What's the ETA on review? I'm hoping to land Bug 882145 for FF26 which uses it now. Let me know and I can back off and use a workaround if need be.

Thanks!

Comment 4

[Jan-Ivar Bruaroey [:jib] (needinfo? me)]

I should add that it works! :-)

Comment 5

[Kyle Huey (Exited; not receiving bugmail, old account, do not use)]

Comment on attachment 803270 [details] [diff] [review]
Give dictionaries copy constructors and assignment operators when it's safe.

Review of attachment 803270 [details] [diff] [review]:
-----------------------------------------------------------------

::: dom/bindings/Codegen.py
@@ +8576,5 @@
>  
> +    @staticmethod
> +    def isDictionaryCopyConstructible(dictionary):
> +        def isTypeCopyConstructible(type):
> +            # Nullable and sequnce stuff doesn't affect copy/constructibility

*sequence

Comment 6

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/mozilla-central/rev/1193eb976c83