Frequently we want to parse "anything that's a `<length-percentage>`" or
similar, which could be a constant value or a calculation, but didn't
have a nice way of doing so. That meant repeating the same "try and
parse a dimension, see if it's the right type, then maybe try and parse
a calculation and see if that's the right type" boilerplate code. Or
more often, forgetting about calculations entirely.
These helpers should make that a lot more convenient to do. And they
also use TokenStream, so we can eventually drop the old `parse_length()`
method.
We don't need to skip whitespace at the top level because that's already
done before we're called. But we do still have to skip it inside the
`add()` function
No functional impact intended. This is just a more complicated way of
writing what we have now.
The goal of this commit is so that we are able to store the 'name' of a
pseudo element for use in serializing 'unknown -webkit-
pseudo-elements', see:
https://www.w3.org/TR/selectors-4/#compat
This is quite awkward, as in pretty much all cases just the selector
type enum is enough, but we will need to cache the name for serializing
these unknown selectors. I can't figure out any reason why we would need
this name anywhere else in the engine, so pretty much everywhere is
still just passing around this raw enum. But this change will allow us
to easily store the name inside of this new struct for when it is needed
for serialization, once those webkit unknown elements are supported by
our engine.
Implemented by adding the extra 3-value syntax as its own case and only
running it when parsing background-position. I'm sure it could be
implemented in a smarter way but this is still a bunch less code than
before. :^)
Having two ways that `<position>` is represented is awkward and
unnecessary. So, let's combine the two paths together. This first step
copies and modifies the `parse_position()` code to produce a
`PositionStyleValue`.
Apart from returning a StyleValue, this also makes use of automatic enum
parsing instead of manually comparing identifier strings.
This one is a bit fun because it can be `add(<integer>)` or `auto-add`,
but children have to inherit the computed value not the specified one.
We also have to compute it before computing the font-size, because of
`font-size: math` which will be implemented later.
Support the optional `<attr-type>` parameter to the `attr()` function,
which allows parsing the attribute's value as a variety of types,
instead of always as a string.
Resolving typed `attr()` functions is going to involve using more
internal Parser methods, so this is the simplest solution for that.
Also... resolving these is basically parsing them, so it makes more
sense for that process to live here.
This is just moving code, with minimal changes so it still works.
