For example, this:
```css
.foo {
color: red;
&:hover {
color: green;
}
}
```
now has the same effect as this:
```css
.foo {
color: red;
}
.foo:hover {
color: green;
}
```
CSSStyleRule now has "absolutized selectors", which are its selectors
with any `&`s resolved. We use these instead of the "real" selectors
when matching them, meaning the style computer doesn't have to know or
care about where the selector appears in the CSS document.
A couple of parts of this:
- Store the source text for Declarations of custom properties.
- Then save that in the UnresolvedStyleValue.
- Serialize UnresolvedStyleValue using the saved source when available -
that is, for custom properties but not for regular properties that
include var() or attr().
In order to know whether `calc(2.5)` is a number or an integer, we have
to see what the property will accept. So, add that knowledge to
`Parser::expand_unresolved_values()`.
This makes `counter-increment: foo calc(2 * var(--n));` work correctly,
in a test I'm working on.
CSS Syntax 3 (https://drafts.csswg.org/css-syntax) has changed
significantly since we implemented it a couple of years ago. Just about
every parsing algorithm has been rewritten in terms of the new token
stream concept, and to support nested styles. As all of those
algorithms call into each other, this is an unfortunately chonky diff.
As part of this, the transitory types (Declaration, Function, AtRule...)
have been rewritten. That's both because we have new requirements of
what they should be and contain, and also because the spec asks us to
create and then gradually modify them in place, which is easier if they
are plain structs.
When the TokenStream code was originally written, there was no such
concept in the CSS Syntax spec. But since then, it's been officially
added, (https://drafts.csswg.org/css-syntax/#css-token-stream) and the
parsing algorithms are described in terms of it. This patch brings our
implementation in line with the spec. A few deprecated TokenStream
methods are left around until their users are also updated to match the
newer spec.
There are a few differences:
- They name things differently. The main confusing one is we had
`next_token()` which consumed a token and returned it, but the spec
has a `next_token()` which peeks the next token. The spec names are
honestly better than what I'd come up with. (`discard_a_token()` is a
nice addition too!)
- We used to store the index of the token that was just consumed, and
they instead store the index of the token that will be consumed next.
This is a perfect breeding ground for off-by-one errors, so I've
finally added a test suite for TokenStream itself.
- We use a transaction system for rewinding, and the spec uses a stack
of "marks", which can be manually rewound to. These should be able to
coexist as long as we stick with marks in the parser spec algorithms,
and stick with transactions elsewhere.
Before this change we were serializing them in a bogus 8-digit hex color
format that isn't actually recognized by HTML.
This code will need more work when we start supporting color spaces
other than sRGB.
Multiple font properties are either the `normal` keyword or some
non-keyword value, so this lets us avoid some boilerplate for those, at
the cost of the existing `none` users having marginally more verbose
code.
This is a special form of `<string>` so doesn't need its own style value
type. It's used in a couple of font-related properties. For completeness
it's included in ValueType.
CSS Fonts level 4 renames font-stretch to font-width, with font-stretch
being left as a legacy alias. Unfortunately the other specs have not yet
been updated, so both terms are used in different places.
When a property is a "legacy name alias", any time it is used in CSS or
via the CSSOM its aliased name is used instead.
(See https://drafts.csswg.org/css-cascade-5/#legacy-name-alias)
This means we only care about the alias when parsing a string as a
PropertyID - and we can just return the PropertyID it is an alias for.
No need for a distinct PropertyID for it, and no need for LibWeb to
care about it at all.
Previously, we had a bunch of these properties, which misused our code
for "logical aliases", some of which I've discovered were not even
fully implemented. But with this change, all that code can go away, and
making a legacy alias is just a case of putting it in the JSON. This
also shrinks `StyleProperties` as it doesn't need to contain data for
these aliases, and removes a whole load of `-webkit-*` spam from the
style inspector.
Logging a parse error when the attribute is not present, is not useful,
but does fill the debug log with errors that hide any real parsing
errors. This patch introduces an early-out in this situation to prevent
this spam.
The following spec algorithms had changed since we implemented them:
- "parse a sizes attribute"
- "update the source set"
- "create a source set"
This commit brings them up to date, as well as adding some additional
logging when parsing the sizes attribute fails in some way.
According to https://www.w3.org/TR/css-grid-2/#placement-shorthands
when setting the 'grid-row' and 'grid-column' shorthand property to a
single <custom-ident> value, both 'grid-row-start'/'grid-column-start'
and 'grid-row-end'/'grid-column-end' should be set to that
<custom_ident>.
Instead of CSSColorValue holding a Gfx::Color, make it an abstract class
with subclasses for each different color function, to match the Typed-OM
spec. This means moving the color calculations from the parsing code to
the `to_color()` method on the style value.
This lets us have calc() inside a color function, instead of having to
fully resolve the color at parse time. The canvas fillStyle tests have
been updated to reflect this.
The other test change is Screenshot/css-color-functions.html: previously
we produced slightly different colors for an alpha of 0.5 and one of
50%, and this incorrect behavior was baked into the test. So now it's
more correct. :^)
"Parse a style value for <foo>", where we don't care if it's a literal
<foo> or a calculated one, is a really common thing that we previously
didn't have methods for.
A couple of methods we had have been extended to parse calc(), and the
others have been filled in.
The method for parsing the `flex` property's value is renamed
`parse_flex_shorthand_value()` as it conflicted.
For simplicity in user code, the `parse_foo_value()` methods should
parse anything that is a `<foo>`. In these cases, that means a
number/integer or calculation that resolves to them.
These uses in parse_css_value_for_properties() specifically only want a
literal IntegerStyleValue/NumberStyleValue, as calc-parsing is done
elsewhere. So, do the parsing for them locally.
Parsing a `Gfx::Color` no longer makes sense, as CSS has many ways of
defining a color, often in a dynamic way where the color value isn't
known until later. This is a small preparatory change before a much
larger color rewrite.
Soon, CSSColorValue will be an abstract class, and we'll instead create
a CSSRGB, CSSHSL, or other specific color type from the Typed-OM spec.
However, it's still useful to have an easy "just give me a style value
for this color" method. So change the name to distinguish this from the
usual StyleValue::create() methods.
We previously had 4 single-instance StyleValues for these keywords.
CSS-Typed-OM expects them keywords to be exposed as CSSKeywordValue, so
it's simpler to treat them the same. The single-instance behaviour is
kept by having StyleValue::create() use a cached instance for each of
these.
For a long time, we've used two terms, inconsistently:
- "Identifier" is a spec term, but refers to a sequence of alphanumeric
characters, which may or may not be a keyword. (Keywords are a
subset of all identifiers.)
- "ValueID" is entirely non-spec, and is directly called a "keyword" in
the CSS specs.
So to avoid confusion as much as possible, let's align with the spec
terminology. I've attempted to change variable names as well, but
obviously we use Keywords in a lot of places in LibWeb and so I may
have missed some.
One exception is that I've not renamed "valid-identifiers" in
Properties.json... I'd like to combine that and the "valid-types" array
together eventually, so there's no benefit to doing an extra rename
now.
