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Re: [cssom] Serializing the ">>" combinator

From: Simon Pieters <simonp@opera.com>
Date: Fri, 13 Feb 2015 09:22:32 +0400
To: "www-style@w3.org" <www-style@w3.org>, "Benjamin Poulain" <benjamin@webkit.org>
Message-ID: <op.xtzljur1idj3kv@simons-macbook-pro.local>
On Fri, 13 Feb 2015 00:05:45 +0400, Benjamin Poulain <benjamin@webkit.org>  
wrote:

> On 2/12/15 1:22 AM, Simon Pieters wrote:
>> On Tue, 10 Feb 2015 09:14:26 +0400, Benjamin Poulain  
>> <benjamin@webkit.org> wrote:
>>
>>> Hi,
>>>
>>> The serialization specification does not mention ">>" from CSS  
>>> Selectors level 4:  
>>> http://dev.w3.org/csswg/cssom/#serializing-selectors &&  
>>> http://dev.w3.org/csswg/selectors-4/#descendant-combinators
>>>
>>> What we have done in WebKit is serialize ">>" like the other non-space  
>>> combinators (e.g. "foo>>bar" serialize to "foo >> bar").
>>>
>>> An other option is to canonicalize every descendant combinator to the  
>>> space character.
>>
>> I've specified it to serialize as a space, for two reasons:
> I am a bit surprised by this. I had the impression the WG favored ">>"  
> over the space.

Personally I see no reason to favor >>. The only reason I have seen for it  
existing at all is that it makes for a "nice" family of combinators >, >>  
and >>>. But it is possible that I'm missing something.

> Plus web developers tend to report bugs when a serialized value differs  
> significantly from the original selector.

Yeah. On the other hand, it is common to normalize semantically equivalent  
things in CSSOM.

>> * It is compatible with legacy UAs that support space but not >>
> How would legacy UI end up with a parsed ">>" in the first place?

It wouldn't. I assumed two UAs, one with >> support and one without, where  
the serialization from one is parsed by the other. I realize that this  
might not be particularly relevant.

>> * It avoids having to remember which one was used when parsing

This is the stronger reason in my opinion. Also see  
https://lists.w3.org/Archives/Public/www-style/2015Jan/0603.html

-- 
Simon Pieters
Opera Software
Received on Friday, 13 February 2015 08:23:03 UTC

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