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[csswg-drafts] [css-text-3] Clarify Segment Break Transformation Rules when mutiple segment breaks involve

From: Xidorn Quan via GitHub <sysbot+gh@w3.org>
Date: Mon, 26 Dec 2016 12:07:44 +0000
To: public-css-archive@w3.org
Message-ID: <issues.opened-197581218-1482754062-sysbot+gh@w3.org>
upsuper has just created a new issue for 
https://github.com/w3c/csswg-drafts:

== [css-text-3] Clarify Segment Break Transformation Rules when 
mutiple segment breaks involve ==
The first rule for collapsing segment breaks is:
> If the character immediately before or immediately after the segment
 break is the zero-width space character (`U+200B`), then the break is
 removed, leaving behind the zero-width space.

It is not clear to me what should happen if there are multiple segment
 breaks involve here. For example, if I have `ZWSP LF LF LF x`, would 
this rule produce:
1. `ZWSP LF LF x` (with only the first `LF` removed), or
2. `ZWSP x` (with all `LF` removed because of recursively applying 
this rule)?

(In the first case, the remaining `LF`s would be converted to 
whitespaces by the last rule there, and the second whitespace would be
 removed by step 4 of Phase I, so the final result would be `ZWSP WS 
x`.)

This may also affect the second rule:
> Otherwise, if the East Asian Width property of both the character 
before and after the line feed is `F`, `W`, or `H` (not `A`), and 
neither side is Hangul, then the segment break is removed.

If I have `W LF LF W`, should the two `LF`s be removed by this rule?

It seems to me that removing all segment breaks together would be 
easier for implementation, so I would propose making the rules that 
way if there are no other concerns.

Please view or discuss this issue at 
https://github.com/w3c/csswg-drafts/issues/836 using your GitHub 
account
Received on Monday, 26 December 2016 12:07:46 UTC

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