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From Gordon Smith <gosm...@adobe.com>
Subject RE: [gosh] On the sad tale of BNF and optional semicolons
Date Wed, 22 Feb 2012 18:14:06 GMT
> I seem to remember reading somewhere that Falcon uses a grammar based approach as well
to parsing  AS3. I'm wondering how they're pulling it off then...

Falcon currently uses an ANTLR 2 grammar to parse ActionScript. We've been improving the grammar
that was previously used for code intelligence in Flash Builder. We expect to move to ANTLR
3 at some point.

We handle semicolons by calling a Java method we wrote, matchOptionalSemicolon(), in the actions
of various productions. We don't try to represent the optional semicolons in the productions
of the grammar itself.

- Gordon Smith, Falcon team, Adobe


-----Original Message-----
From: Roland Zwaga [mailto:roland@stackandheap.com] 
Sent: Wednesday, February 22, 2012 4:52 AM
To: flex-dev@incubator.apache.org
Subject: Re: [gosh] On the sad tale of BNF and optional semicolons

>
> Everything I've read points to the same thing: EcmaScript-style 
> languages cannot be expressed as BNF. I suspect that the reason why 
> Adobe are talking about the changes to language in the Falcon compiler 
> breaking some existing
> AS3 projects is because they have had to modify the language to make 
> it definable in something like BNF.
>

I seem to remember reading somewhere that Falcon uses a grammar based approach as well to
parsing  AS3. I'm wondering how they're pulling it off then...

Roland

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