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.
Originally, the input was named `tokens`, and we later created a
`tokens_without_whitespace` from the filtered contents of `tokens`.
Since `tokens_without_whitespace` is what we actually want to use while
parsing, let's rename `tokens` -> `unprocessed_tokens` and use the
`tokens` name for the processed ones.
There were two bugs here, one of which hid the other:
- Only one offset would have a value, but we dereferenced both.
- We consumed a token whether it was a valid offset or not.
This removes a performance problem where we'd convert the style sheet's
default namespace from DeprecatedFlyString to FlyString once per rule
during selector matching.
The conversion now happens once, during CSS parse. It should eventually
be removed from there as well, but one step at a time. :^)
