On May 2, 2008, at 5:35 PM, Jonas Sicking wrote:
One alternative solution would be to say that the string ":scope " is always prepended to the passed in selector. That would mean that a selector like "div span" would be matched as ":scope div span" where obviously the "div" and "span" parts can only match descendants of the context node, and selection can never leak out outside the context node. It would even make a selector like "> div" work since it would be matched as ":scope > div" which is a valid selector.
I proposed something similar on #whatwg today, that we add queryScopedSelector / queryScopedSelectorAll to elements, which has this behavior. See <http://krijnhoetmer.nl/irc-logs/whatwg/20080503#l-190 > for discussion.
Yes, if we wanted this to handle cases like "div, p" right, you can't just do a simple prepend of ":scope", you have to treat it as ":scope div, :scope p". Such an API would make clear that we were introducing a new notion of "scoped selector" which differs from selectors in the CSS sense. Also, this could be specified in Selectors API without waiting for :scope to make it into a spec, by saying the selector acts as if some simple selector that uniquely matches the scope node had been prepended to each selector in the group.
The only real downside with that proposal is that the passed in selector is not a valid selector. And it doesn't work really well for selector groups such as "div, span", where what you'd really want is for ":scope" to be prepended to each group, which makes parsing a lot of fun...
Yes, unfortunately I think significant parsing hackery would be required to handle this. Either a second Selector parser, or a special pre-parser that could inject ":scope" or nonstandard equivalent in the right places. Or we could just say that a "scoped selector" can only be a selector, not a group of selectors, so commas are a syntax error.
Regards, Maciej
