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Re: [css-syntax] Moving away from a state machine (was: Ready for wide review, FPWD request coming soon)

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Thu, 30 May 2013 10:51:11 -0700
Message-ID: <CAAWBYDCQ7tBXg4A7yYVTxG-jOABWu2WR7wtKKuTkBPbx=n5MgQ@mail.gmail.com>
To: Simon Sapin <simon.sapin@exyr.org>
Cc: Zack Weinberg <zackw@panix.com>, www-style list <www-style@w3.org>
On Thu, May 30, 2013 at 2:57 AM, Simon Sapin <simon.sapin@exyr.org> wrote:
> Le 20/05/2013 08:04, Zack Weinberg a écrit :
>> Attached is an edited version of the 17 May draft with the
>> number/percentage/dimension tokenization rewritten as I had in mind.  It
>> could probably stand a little polish, but I think this should give you
>> an idea of what it would be like.  This reflects about four hours'
>> effort and I think that was more than half of the work required to
>> convert the whole scanner to this style.  (CSS numbers are messy.)
>>
>> I wound up partially converting identifier scanning as well, because it
>> was convenient to have a "consume a sequence of name characters"
>> subroutine to handle DIMENSIONs, and once you have that, using it for
>> IDENT, HASH and AT-KEYWORD as well is trivial.
>
> I am definitely in favor switching the tokenizer to the same style as the
> parser, that is a bunch of "functions" calling each other rather than a
> state machine. This is easier to think about, an can actually make the spec
> simpler by removing quite a bit of duplication:
>
> * String and URL tokens can call the same "Consume a quoted string"
> function.
>
> * Idents, hash, at-keywords and dimensions tokens can call the same "Consume
> a 'name'" function, where a name is made of "name characters" and escapes.
> (The restrictions on identifiers is checked before this function is called.)

Yes, I'm planning to accept Zack's change and refit the rest of the
tokenizer into this style as well.

>> I suspect the table of contents and index are mangled.  Are they
>> autogenerated somehow?
>
> The source of the editor’s drafts are version-controlled in Mercurial and
> have a Git mirror:
>
> https://dvcs.w3.org/hg/csswg/
> https://github.com/w3c/csswg-drafts
>
> Unfortunately, the generator is a Member-only web service:
> http://wiki.csswg.org/tools/spec-processor

I responded to Zack privately about this, but I plan to switch the
spec over to my preprocessor soonish.

~TJ
Received on Thursday, 30 May 2013 17:52:01 UTC

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