[Rubygrammar-grammarians] Ruby Grammar Project

[Terence Parr]

On Nov 26, 2005, at 12:46 PM, Ryan Davis wrote:
> Hey Terr, long time no email... It has been many many years.

Howdy do!  Long time...

> I think I can help here. 1) yes, ruby has ties smalltalk, but  
> nowhere near the grammar side of things. You'll just have to let go  
> of that. It is much more of a loose java grammar than it is a  
> smalltalk grammar.

Ok, i'm letting go :)

> 2) I have tools to help this exploration process along quite easily:
>
> 509 % echo "foo bar baz" | parse_tree_show -f
> (eval):1: warning: parenthesize argument(s) for future version
> [[:class,
>   :Example,
>   :Object,
>   [:defn,
>    :example,
>    [:scope,
>     [:block,
>      [:args],
>      [:fcall, :foo, [:array, [:fcall, :bar, [:array,  
> [:vcall, :baz]]]]]]]]]]

Looks cool/useful.  Why the :array node?

> This is in my package ParseTree, which you can easily install via  
> 'sudo gem install -y ParseTree' assuming you have rubygems installed.

Not yet.

> I tried doing an LR2LL flip on ruby about 2 years ago and got  
> stymied. It wasn't nearly as easy as doing smalltalk and I can't  
> keep the whole grammar in my head. I've started working on a tool  
> for grammar exploration/experimentation (tentatively called  
> yaccpuke or GIT - grammar inspection toolkit). It hopes to do only  
> a few things, but do them well:
>
> 1) provide a simple DSL for describing grammars by hand ( from  
> smalltalk: bod [ uod | be ] )
> 2) ability to read in y.output (stripped grammar from yacc when run  
> w/ -v)
> 3) provide an interactive session (via irb) with api to explore and  
> manipulate grammar rules ( grammar.cycles? and grammar[:bod].replace 
> (:be))

Interesting. :)

> I've got 1 & 2 down and am extending 3 right now. I'm hoping that  
> when this tool is done enough it'll provide me the extra brainpower  
> to do the LR2LL flip on ruby's yacc based grammar.
>
> I haven't been tracking what you've been up to Terr. I stopped  
> using Antlr in the early v2 days (mostly because I stopped coding  
> in java and C++ as much as possible) so I don't know if you've done  
> more work in this area.

Well, ANTLR v3 is Soooo much more powerful and easy to use.  Plus we  
have ANTLRWorks http://www.antlr.org/works now too, a grammar dev  
environment.

> I should also point out the work being done by Don Roberts and John  
> Brant (of refactoring browser fame). They are working on a suite of  
> tools that can be taught a new language and then spit out a new  
> refactoring browser for that language. They said that in about a  
> month (about now actually) they'd be done with C# and able to work  
> on back-porting the system into squeak. They have a lot of  
> experience in this area and might want to bite off a chunk as well.  
> At the very least, the sooner we can get the grammar into a more  
> digestible form, the sooner we can have a feature-complete  
> refactoring browser!

Yep, getting a nice easy-to-use grammar together should be useful.   
My main interest at the moment is making a real grammar for testing  
ANTLR v3. :)

Ter