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Re: [css3-values] Order-sensitive "one or more" component value combinator

From: fantasai <fantasai.lists@inkedblade.net>
Date: Fri, 20 Apr 2012 17:03:27 -0700
Message-ID: <4F91F94F.1050600@inkedblade.net>
To: "www-style@w3.org" <www-style@w3.org>
On 04/20/2012 04:16 PM, Tab Atkins Jr. wrote:
> On Fri, Apr 20, 2012 at 3:04 PM, fantasai<fantasai.lists@inkedblade.net>  wrote:
>> There's a few places where our grammars would be much simpler (less
>> repetition)
>> if we had a combinator that meant "this or that or both, but in this order".
>> (We have the double-bar, which means "this or that or both", but there's no
>> ordering requirement there.)
>
> Note that we already have a "zero or more of these, in order" pattern:
>
> a? b? c?
>
> It's just that implementing a "one or more of these, in order" pattern
> requires some confusing grammar contortions:
>
> [
>    a b? c?
> |
>    b c?
> |
>    c
> ]
>
> This is obviously ugly, confusing, and repetitive.
>
> However, the only place I know of that uses this pattern is the
> radial-gradient() grammar.
> ...
> So anyway, are there more places that would benefit from "one or more,
> in this order" than radial-gradient()?

Yes, I think I might wind up using it in one of the Text features,
which is why I brought it up. (Haven't written up the appropriate
emails yet, though. And maybe we wind up not doing that.)

It would also simplify the grammar for 'border-image', could be used
to make <bg-position> optional when <bg-size> is specified in 'background',
and would have removed the first clause in the <position> syntax.

~fantasai
Received on Saturday, 21 April 2012 00:03:58 GMT

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