As noted, this is hacky because the parser wasn't written to allow
parsing an individual component of a selector. (Fox example, the
convenient-sounding `parse_pseudo_simple_selector()` assumes the first
colon has already been consumed...) So until that changes, this parses
the input as an entire selector-list, and then throws it away if it's
not a single pseudo-element selector.
It's only temporary though, I promise. 😅
These have a few rules that we didn't follow in most cases:
- CSS-wide keywords are not allowed. (inherit, initial, etc)
- `default` is not allowed.
- The above and any other disallowed identifiers must be tested
case-insensitively.
This introduces a `parse_custom_ident_value()` method, which takes a
list of disallowed identifier names, and handles the above rules.
This is `counter(name, style?)` or `counters(name, link, style?)`. The
difference being, `counter()` matches only the nearest level (eg, "1"),
and `counters()` combines all the levels in the tree (eg, "3.4.1").
These control the state of CSS counters.
Parsing code for `reversed(counter-name)` is implemented, but disabled
for now until we are able to resolve values for those.
The new method is Parser::parse_all_as_single_none_value(), which has a
few advantages:
1. There's no need for user code to manually create a StyleValue.
2. It consumes tokens so that doesn't have to be done manually.
3. Whitespace before or after the `none` is consumed correctly.
It does mean we create and then discard a `none` StyleValue in a couple
of places, namely parsing for `grid-*` properties. We may or may not
want to migrate those to returning the IdentifierStyleValue instead.
This fixes an issue where :host(foo) would parse as if "foo" was the
on the right side of a descendant combinator.
Not testable yet, but will be in the next commit.
When loading a canned version of reddit.com, we end up parsing many many
shadow tree style sheets of roughly ~170 KiB text each.
None of them have '\r' or '\f', yet we spend 2-3 ms for each sheet just
looping over and reconstructing the text to see if we need to normalize
any newlines.
This patch makes the common case faster in two ways:
- We use TextCodec::Decoder::to_utf8() instead of process()
This way, we do a one-shot fast validation and conversion to UTF-8,
instead of using the generic code-point-at-a-time callback API.
- We scan for '\r' and '\f' before filtering, and if neither is present,
we simply use the unfiltered string.
With these changes, we now spend 0 ms in the filtering function for the
vast majority of style sheets I've seen so far.
We already have a FlyString of its value from parsing, and most users
also want a FlyString from it, so let's use that instead of converting
backwards and forwards.
The two users that did want a String are:
- Quotes, which make sense as FlyString instead, so I've converted that.
- Animation names, which should probably be FlyString too, but the code
currently also allows for other kinds of StyleValue, and I don't want
to dive into this right now to figure out if that's needed or not.
The values aren't that complex, so it doesn't make much sense to have a
dedicated generator for them. Parsing them manually also allows us to
have much more control over the produced values, so as a result of this
change, EasingStyleValue becomes much more ergonomic.
This lets us remove the color/dimension-parsing lambdas, since these
always forwarded to the same methods. This will make it easier to later
convert those methods to take a TokenStream.
As the parser was trying to directly unwrap an unresolved duration.
Currently we are outputting the wrong results for the serialized
duration, but this is still a step forwards.
Fixes a crash seen on: https://evaparish.com/blog/how-i-edit
Before this change, every CSS @supports rule would keep the containing
JS realm alive via a JS::Handle. This led to a GC reference cycle and
the whole realm leaked.
Since we only need the realm at construction time, we can take it as a
parameter instead, and stop storing it.
