Beefy Boxes and Bandwidth Generously Provided by pair Networks
laziness, impatience, and hubris
 
PerlMonks  

Re: Re: Parse::JavaScript

by OeufMayo (Curate)
on Aug 27, 2002 at 08:45 UTC ( #193103=note: print w/ replies, xml ) Need Help??


in reply to Re: Parse::JavaScript
in thread JavaScript::Parse::PurePerl (was Parse::JavaScript)

Thanks for your input podmaster. Here are a few valid JavaScript samples that don't parse too well.

Regexes

var foo = 3 / 4 + 1 / 2;

is parsed as :

var foo = 3; / 4 + 1 /; 2;

var foo = (3/4) + 1 / 2; is not parsed at all (though I suspect it could be fixed by adjusting the precedence)

Elisions (though I have yet to see this construct in a real script)

var foo = foo[ , , bar];

Wrong parsing

bar ++foo;

Is parsed as:

bar++; foo;

Which is wrong. the parser should give an error (no line terminator allowed between 'bar' and '++') or be nice and get parse it as bar++;foo;

The following code is found in one of the the mozilla/js test script, but it doesn't seem to be valid, according to the specs (and obviously, doesn't parse).

try { //some stuff }catch (e if e == 3){ /* do stuff */ }

There are probably some more bugs, but the regex/division confusion is by far the most annoying

Update here is another major bugs due to the Optional Semicolon:

return a + b

Should be:

return; a + b;

But it is parsed as

return a + b;

This bug is mainly due to the fact that line terminators are silently skipped by the lexer

Update 2002-09-01: I'm glad to say that all these bugs are now fixed in the current version of this node (except for the elision.)

-- 
briac


Comment on Re: Re: Parse::JavaScript
Select or Download Code
Re: Re: Re: Parse::JavaScript
by Corion (Pope) on Aug 27, 2002 at 19:47 UTC

    Very interesting code and discussion - but my internal parser parses

    bar++ foo;
    as
    bar+ +foo;

    which would be instantly valid. But on the other side, I don't know much about JavaScript (and C-style) operator syntax, and maybe two pluses automatically mean postincrement / preincrement operator ...

    perl -MHTTP::Daemon -MHTTP::Response -MLWP::Simple -e ' ; # The $d = new HTTP::Daemon and fork and getprint $d->url and exit;#spider ($c = $d->accept())->get_request(); $c->send_response( new #in the HTTP::Response(200,$_,$_,qq(Just another Perl hacker\n))); ' # web

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://193103]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others surveying the Monastery: (6)
As of 2015-07-05 06:03 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    The top three priorities of my open tasks are (in descending order of likelihood to be worked on) ...









    Results (60 votes), past polls