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[css-mediaqueries] whitespace handling

From: Florian Rivoal <florian@rivoal.net>
Date: Mon, 08 Jul 2013 12:35:07 +0200
To: www-style@w3.org
Message-ID: <op.wzwfotaef5de51@localhost.localdomain>
On Wed, 03 Jul 2013 12:55:16 +0200, Simon Sapin <simon.sapin@exyr.org>
wrote:

> Le 03/07/2013 06:57, fantasai a écrit :
>> Parens and Escapes
>> ------------------
>>
>>     - RESOLVED: MQ requires white-space on both sides of a parenthesis
>
> I believe that this is an incorrect summary of the change we discussed.
>
> The change is rather to require whitespace on both sides of the 'and'  
> keyword (and 'or', when and if we add it) when that would separate form  
> the "outside" of a parenthesis. That is:
>
>      ) and
>
>      and (
>
> Note that 'and(', being a FUNCTION token, was already invalid. But using  
> S+ rather than S* in the grammar avoids incorrectly suggesting that it  
> is valid. This change only affects 'and/**/(', as well as ')and' for  
> symmetry.

An errata was published for this. I don't think it is right, so I'd like  
to reopen this.

http://www.w3.org/Style/2012/REC-mediaqueries-20120619-errata.html

This does almost what Simon said, but not quite: it requires spaces on
both sides of "and" when used between media features, but only requires
space after "and", not before, if and is after a media type. So this is
allowed:

@media screen/**/and (min-width: 100px) { .... }

This that what we want? I would think not, this isn't very consistent with  
the fact that we have disallowed the following 2:  I

@media (min-height: 100px)/**/and (min-width: 100px) { .... }
@supports (height: 100px)/**/and (width: 100px) { .... }

In addition to this, in @supports, NOT is followed by S+, not S*. As long  
as we are harmonizing, I suggest we do the same in media queries as well.

Based on all that, I suggest we change the grammar (im MQ3 errata and MQ4)  
to this:

media_query
    : [ONLY | NOT]? S+ media_type S* [S AND S+ expression ]*
      | expression [ S AND S+ expression ]*
    ;

Thoughts?

- Florian
Received on Monday, 8 July 2013 10:35:40 UTC

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