Re: [csswg-drafts] [css-env] Consider value-level parsing like calc() rather than token-level like var()

I don't think this is possible. calc() can be value-level because it resolves to a single leaf value in the grammars. The built-in env()s already have things that resolve to multiple values, however, and we don't have productions to recognize those.  Author-defined env() will be even wider, with no control over what's put in there.

However, the "infection" behavior of var() isn't quite present here. You don't have  to wait for any other values to be set up before you resolve it; you can just sub it in during parsing, and then invalidate the thing it's used in like normal.  My current plan for author-defined env() is to just provide a JS API too (not a CSS rule), so that invariant will be maintained anyway.  Should I make that clearer in the spec, to help guide implementation?

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Received on Monday, 5 November 2018 18:55:29 UTC