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Re: [mediaqueries] @media screen and (foo) or (baz)

From: Henrik Andersson <henke@henke37.cjb.net>
Date: Mon, 23 Mar 2015 18:56:17 +0100
Message-ID: <551053C1.8060805@henke37.cjb.net>
To: Simon Sapin <simon.sapin@exyr.org>, www-style list <www-style@w3.org>
Simon Sapin skrev:
> MQ Level 4 extends the syntax to allow arbitrary nesting of "not",
> "and", and "or" boolean operators. It avoids the question of whether
> `A or B and C` should be interpreted as `A or (B and C)` or `(A or B)
> and C` by requiring the parentheses:
>
> Extract of the grammar:
>
>> <media-condition> = <media-not> | <media-and> | <media-or> |
>> <media-in-parens>
>> <media-not> = not <media-in-parens>
>> <media-and> = <media-in-parens> [ and <media-in-parens> ]+
>> <media-or> = <media-in-parens> [ or <media-in-parens> ]+
>> <media-in-parens> = ( <media-condition> ) | <media-feature> |
>> <general-enclosed>
>
>
> However, there is one case left that may seem ambiguous. The
> <media-query> grammar:
>
>> <media-query> = <media-condition>
>>              | [ not | only ]? <media-type> [ and <media-condition> ]?
>
> accepts `<media-type> and <media-or>`, e.g. `screen and (foo) or (bar)`.
>
> The grammar makes it unambiguously the same as `screen and ((foo) or
> (bar))`, but that’s not obvious without referring to the spec.
>
>
> Should the grammar be restricted to require parenthenses in this case
> as well?
>
Given that or traditionally has lower predecease than and, it's
certainly confusing.
Received on Monday, 23 March 2015 17:56:55 UTC

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