Implement template strings

[gbrail]

The Node.js 4.0 developers seem to love these.

[tuchida]

ref. #81
What would you do to @anba's PR?

[gbrail]

Yeah, I'm trying to merge that and it does not look terribly difficult. Of course, it's not a simple merge either given that it goes in the same few files where everything else has changed. But let me see if I can make progress.

[p-bakker]

@gbrail I've merged the Patch 2 & 3 part of #81 onto the latest master in my fork: https://github.com/p-bakker/rhino/tree/template-strings

I ran the latest tests from String.raw from test262 main's branch against it and the ones that fail seem to be related to tagged templates, see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Template_literals#Tagged_template_literals

Am trying to grasp the changes @anba made, but so far I think that Tagged Template support just wasn't covered. Might not have been part of the draft spec at the time he implemented these changes

[gausie]

@p-bakker I know its been a while; do you have any intention on resuming your work on this? If not would you be alright with someone picking up from where you left off?

[p-bakker]

Hi @gausie

It's indeed been a while, priorities shifted, will be a few months before I'd be able to get back to it.

I managed to get it to pass all tests from the Test262 testsuite, not sure if I committed all the changes I made to my fork yet. Also don't recall from the top of my head the exact reason why I haven't put it up as a PR yet.

Would need to spent some time on it to see where things stand

[gausie]

It looks so close to being done and a project I'm involved with would make massive use of the feature, so I'm looking forward to seeing a PR when you're ready! Thanks for your work so far.

[p-bakker]

I hear you, whenever I have to switch back to writing JS code for execution in Node to writing JS code for execution in Rhino, it feels rather clumsy, not having all the latest 'gadgets' available, including Template strings.

I had a quick look and I have uncommitted changes related to Template Strings. Will see if I can at least commit those to my branch over the course of the next couple of weeks, so if someone want to pick up getting this branch merge, they at least don't have to redo work I've already done. Will report back here when I have committed those changes

FYI: I started reviving the Template String work just to be able to enable newer Test262 tests that make use of Template strings while trying to implement Proxy & Reflect. There the challenge is that the internals of Rhino and some of the public Interfaces aren't up to date with the current state of EcmaScript...