"Arbitrary substitution functions" are a family of functions that
includes var() and attr(). All of them resolve to an arbitrary set of
component values that are not known at parse-time, so they have to be
substituted at computed-value time.
Besides it being nice to follow the spec closely, this means we'll be
able to implement the others (such as `if()` and `inherit()`) more
easily.
The main omission here is the new "spread syntax", which can be
implemented in the future.
This has an extra parameter to allow stopping at the first comma token,
which we need for var() and attr()'s "argument grammar".
Co-authored-by: Tim Ledbetter <tim.ledbetter@ladybird.org>
Custom properties are required to produce a computed value just like
regular properties. The computed value is defined in the spec as
"specified value with variables substituted, or the guaranteed-invalid
value", though in reality all arbitrary substitution functions should be
substituted, not just `var()`.
To support this, we parse the CSS-wide keywords normally in custom
properties, instead of ignoring them. We don't yet handle all of them
properly, and because that will require us to cascade them like regular
properties. This is just enough to prevent regressions when implementing
ASFs.
Our output in this new test is not quite correct, because of the awkward
way we handle whitespace in property values - so it has 3 spaces in the
middle instead of 1, until that's fixed.
It's possible this computed-value production should go in
cascade_custom_properties(), but I had issues with that. Hopefully once
we start cascading custom properties properly, it'll be clearer how
this should all work.
Previously the type argument in attr() could be the name of a CSS type
on its own. This has changed, and now only `raw-string`
(previously `string`) or the name of a dimension unit is allowed. Other
types and more complex grammar use the `type()` function, which we
don't yet support.
I've updated the syntax comment, but not the algorithm itself, which
will be reimplemented in a later commit.
This brings parsing of grid-row-* and grid-column-* properties (and
their associated shorthands) more inline with spec.
Changes:
- Only set omitted properties for combined-value shorthands (e.g.
`grid-row: a` rather than `grid-row: a / b`) if the single value is
`<custom-ident>`.
- `[ [ <integer [-∞,-1]> | <integer [1,∞]> ] && <custom-ident>? ]`:
- Properly resolve `calc`s for `<integer>` that rely on compute-time
information.
- `[ span && [ <integer [1,∞]> || <custom-ident> ] ]`
- Allow `calc`s for `<integer>`
- Allow `<custom-ident>`
There is still work to be done to properly use these parsed values.
Gains us 46 WPT tests.
Our floating point number parser was based on the fast_float library:
https://github.com/fastfloat/fast_float
However, our implementation only supports 8-bit characters. To support
UTF-16, we will need to be able to convert char16_t-based strings to
numbers as well. This works out-of-the-box with fast_float.
We can also use fast_float for integer parsing.
Previously, we would allow calc values such as `calc(min(1 2))`, which
would be simplified to `calc(3)` because we assumed that numbers not
separated by an operator represented a sum. We now validate that the
number of operators we see is as we would expect before collecting
these values into a sum node.
Reimplements `grid`, `grid-template`, `grid-template-rows`, and
`grid-template-columns` in a way that uses a separate function for each
grammar rule defined in the specification. This change results in many
additional passing tests from the already imported WPT suite. Most of
the remaining test failures are related to incorrect serialization of
grid properties.
url() has some limitations because of allowing unquoted URLs as its
contents. For example, it can't use `var()`. To get around this, there's
an alternative `src()` function which behaves the same as `url()` except
that it is parsed as a regular function, which makes `var()` and friends
work properly.
There's no WPT test for this as far as I can tell, so I added our own.
A couple of differences from before:
- Only the fixed set of strings are allowed. Some formats can only be an
ident (eg, svg).
- We don't allow these foo-variations values in ident form.
- The comparison is done case-insensitively. It's unclear if this is
more or less correct, but as most things in CSS are insensitive,
including idents, it makes sense that these would be too.
"format(woff-variations)" and pals are supposed to expand like so:
"format(woff) tech(variations)".
However, since we don't support tech() yet, this patch just adds a small
hack where we still treat "woff-variations" as "woff" so that fonts
load and get used, even if we don't make use of the variations yet.
Previously, we would just assign the UnresolvedStyleValue to each
longhand, which was completely wrong but happened to work if it was a
ShorthandStyleValue (because that's basically a list of "set property X
to Y", and doesn't care which property it's the value of).
For example, the included `var-in-margin-shorthand.html` test would:
1. Set `margin-top` to `var(--a) 10px`
2. Resolve it to `margin-top: 5px 10px`
3. Reject that as invalid
What now happens is:
1. Set `margin-top` to a PendingSubstitutionValue
2. Resolve `margin` to `5px 10px`
3. Expand that out into its longhands
4. `margin-top` is `5px` 🎉
In order to support this, `for_each_property_expanding_shorthands()` now
runs the callback for the shorthand too if it's an unresolved or
pending-substitution value. This is so that we can store those in the
CascadedProperties until they can be resolved - otherwise, by the time
we want to resolve them, we don't have them any more.
`cascade_declarations()` has an unfortunate hack: it tracks, for each
declaration, which properties have already been given values, so that
it can avoid overwriting an actual value with a pending one. This is
necessary because of the unfortunate way that CSSStyleProperties holds
expanded longhands, and not just the original declarations. The spec
disagrees with itself about this, but we do need to do that expansion
for `element.style` to work correctly. This HashTable is unfortunate
but it does solve the problem until a better solution can be found.
ParsedFontFace and FontLoader now both keep track of which
CSSStyleSheet (if any) was the source of the font-face, so the URLs can
be completed correctly.
Math functions like abs(), clamp(), round(), etc, can be used by
themselves in property values, without wrapping them in calc().
Before this change, we were neglecting to run calc simplification on the
generated calculation node trees. By doing that manually after parsing a
standalone math function, we score at least a couple hundred WPT points.
We now don't absolutize the URL during parsing, keeping it as a CSS::URL
object which we then pass to the "fetch an external image for a
stylesheet" algorithm. Our version of this algorithm is a bit ad-hoc,
in order to make use of SharedResourceRequest. To try and reduce
duplication, I've pulled all of fetch_a_style_resource() into a static
function, apart from the "actually do the fetch" step.
Our previous approach to `<url>` had a couple of issues:
- We'd complete the URL during parsing, when we should actually keep it
as the original string until it's used.
- There's nowhere for us to store `<url-modifier>`s on a `URL::URL`.
So, `CSS::URL` is a solution to this. It holds the original URL string,
and later will also hold any modifiers. This commit parses all `<url>`s
as `CSS::URL`, but then converts it into a `URL::URL`, so no user code
is changed. These will be modified in subsequent commits.
For `@namespace`, we were never supposed to complete the URL at all, so
this makes that more correct already. However, in practice all
`@namespace`s are absolute URLs already, so this should have no
observable effects.
To prepare for introducing a CSS::URL type, we need to qualify any use
of LibURL as `::URL::foo` instead of `URL::foo` so the compiler doesn't
get confused.
Many of these uses will be replaced, but I don't want to mix this in
with what will likely already be a large change.
This commit disallows "default" as a font-family name, when the name is
not quoted because unquoted names are treated as custom-idents, for
which the name "default" is not allowed.
The goal here is to do something a bit smarter with the parsing here
than we do for properties. Instead of the JSON saying "here are the
values, and here are the keywords, and we can have up to 3", here we
place the syntax in the JSON directly (though currently broken up as
one string per option) and then we attempt to parse each one in
sequence. It's something we'll need eventually for `@property` among
other things.
...However, in this first pass, I've gone with the simplest option of
hard-coding the types instead of figuring them out properly. So there's
a PositivePercentage type and a UnicodeRangeTokens type, instead of
properly implementing the grammar for those in a generic way.
The `transform` property supports transform functions that sometimes
need their `calc(percentage)` values to be converted to a number instead
of a length. Currently this only applies to the `scale*` family of
functions, which are marked as such in `TransformFunctions.json`.
We were not consistently applying the `NumberPercentage` type to these
functions though, and in addition, any `NumberPercentage` value would
not consider calculated values.
The upcoming generated types will match those for pseudo-classes: A
PseudoElementSelector type, that then holds a PseudoElement enum
defining what it is. That enum will be at the top level in the Web::CSS
namespace.
In order to keep the diffs clearer, this commit renames and moves the
types, and then a following one will replace the handwritten enum with
a generated one.
