Re: Proposal for limited :matches pseudoclass

Tab Atkins Jr. wrote:
> Got it there at the end.  The + and ~ combinators seem to be naturally 
> symmetric, thus whether you match forward or backward doesn't seem to 
> make a difference in the complexity (to me, at least).

But there is a fundamental asymmetry in DOM mutations.  During parsing, 
you always add chidren and later siblings, almost never previous 
siblings, and never ancestors.

Once the page is all loaded, of course, things are a lot more symmetric.

-Boris