hamlit: performance degraded due to missing Ripper.lex

[k0kubun]

I added truffleruby support of Hamlit in k0kubun/hamlit#145, but it disabled various optimizations because Ripper.lex is not available in truffleruby.

It also complicated its implementation to guard against missing Ripper.lex. I really want truffleruby to support Ripper.lex, to make it easier to maintain the truffleruby support. Is there any plan to support Ripper.lex?

related to: #1712

[eregon]

Thank you again for adding TruffleRuby support in Hamlit.

We'll try to support Ripper.lex, it's one of the few missing stdlibs remaining: https://github.com/oracle/truffleruby/blob/master/doc/user/compatibility.md#standard-libraries

I expect there are no major issues to implement it, we can probably use a similar approach to JRuby as we share basically the same lexer and parser.

Note: this is also blocking haml (#1712)

[eregon]

Relates to #1585

[bjfish]

@k0kubun Ripper has now been implemented and Ripper.lex is supported. Please let us know if you have any issues.