[pypy-dev] Fwd: New Javascript parser in the works

Leonardo Santagada santagada at gmail.com
Sat Apr 28 16:08:46 CEST 2007

Em 28/04/2007, às 09:47, Florian Schulze escreveu:
> This is the biggest and hardest problem about js parsing. The spec  
> does
> define how to handle it, I'm not sure now how the grammar reflects  
> that
> though. Looking at C doesn't help, because there it always needs to be
> present and can't be replaced with newlines. The problem with a js  
> parser
> is, that newlines aren't really whitespace, just like in python.  
> But the
> rules are weird, because newlines are only sometimes relevant, not
> everytime. A js parser which doesn't handle this correctly is in my
> opinion just wrong. You couldn't parse any real world javascript  
> with it

internet exlporer doens't do ASI (automatic semicolon insertion for  
now own I will call it ASI) properly so for you account it is  
wrong... If I remember currently all modern javascript frameworks use  
ES (explicit semicolon) because of diferences in real world parsers.  
What we can do is provide a tool to put the ; on your legacy code,  
but that is something that people should be doing anyway so it is not  
a biggie for me. So I am going with ES for now... when cfbolz and I  
get some time together to work on making it work  then we can try to  
be exactly to the spec. And the formal grammar doesn't reflect this  
at all, besides being wrong (there is an errata in the mozilla site  
that fixes it a bit) and have some parts missing, it completely  
ignores ASI and the present it as textual information (a very very  
informal specification).

I'm going to focus on making a real test suite for my js parser... if  
it doesn't drive me crazy I will be back here.

> .
> Regards,
> Florian Schulze

Leonardo Santagada
santagada at gmail.com

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