[css-grid] Clarification about <auto-track-list> and <line-names> syntaxes

[lahmatiy]

Spec: https://drafts.csswg.org/css-grid/#typedef-auto-track-list

The spec defines <auto-track-list> syntax as following:

[ <line-names>? [ <fixed-size> | <fixed-repeat> ] ]* <line-names>? <auto-repeat>
[ <line-names>? [ <fixed-size> | <fixed-repeat> ] ]* <line-names>?

I suppose | combinator is missed in that syntax.

<line-names> is defined as following:

'[' <custom-ident>* ']'

According to this syntax, an empty brackets is a valid value for the <line-names>. It looks odd, I guess * multiplier should be replaced for +.

[tabatkins]

I suppose | combinator is missed in that syntax.

No, it's written correctly. The point is that you can have one <auto-repeat>, but then as many <fixed-repeat>s as you want before/after it.

According to this syntax, an empty brackets is a valid value for the . It looks odd, I guess * multiplier should be replaced for +.

I don't see anything particularly wrong with allowing [] there. Yeah, it defines no line names, but that seems clear. And allowing it has some good points: it can make it slightly easier for code-generators (don't need to test for the presence of line names and manually omit the [] when generating a template); and it can help visually line things up if people are naming lines between most of the tracks and want the symmetry of having an empty [] calling out that there's no named lines there.