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Re: [css-syntax] Removed <unicode-range-token>, please review

From: John Daggett <jdaggett@mozilla.com>
Date: Thu, 13 Nov 2014 19:42:22 -0800 (PST)
To: www-style list <www-style@w3.org>
Message-ID: <1181869132.11918402.1415936542899.JavaMail.zimbra@mozilla.com>

Tab Atkins wrote:

> Per the resolution from the 2014-07-02 telcon, I've removed the
> <unicode-range-token> from Syntax entirely, and replaced it with a
> <urange> microsyntax: <http://dev.w3.org/csswg/css-syntax/#urange>
> 
> If you're interested in this kind of thing, please give it a look-over
> and verify that I haven't missed any cases or made any mistakes.  It
> was simpler than I thought it would be to spec out.

Tab, this doesn't seem like a good change. The underlying problem is
in the *tokenization* aspect of UNICODE-RANGE. If you eliminate the
token, I'm not sure I see the reason to try and describe the syntax
within the Syntax spec when it's used in only one place, namely the
definition of the 'unicode-range' descriptor.

You've created language here that not only overlaps the existing
definition of valid syntax as defined in the Fonts spec, but it
conflicts with that definition and, more importantly, conflicts with
the behavior of all existing implementations.

> In section 7.1:
> 
> To determine what codepoints the <urange> represents:
> 
> 1. If end value is greater than the maximum allowed code point, set
>    it to the maximum allowed code point.

No, this is invalid syntax and the descriptor defintion should be rejected.

> 2. If start value is greater than end value, the <urange>
>    represents an empty range of codepoints.

Ditto. Plus you introduce serialization problems by allowing "empty
range". I went through this with the Fonts spec, that's why it isn't
defined this way. :)

Cheers,

John Daggett
Received on Friday, 14 November 2014 03:42:52 UTC

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