Hey all, I'd like to give an update on this. @rintaro has picked up and continued development on this since Jan's GSoC project concluded, but unfortunately finishing this project is going to take significantly longer than we anticipated. There are other more urgent tasks that require our attention and focus.
We've made the difficult decision to pause development on this for now and resume it at a later point. We've put the existing parser refactoring changes in a separate branch and reverted them from master. We needed to revert from master because the changes were causing serious performance regression which is not avoidable until we complete the parser migration.
We are intending to periodically keep the new branch working so that we can easily resume this project at a later point.