servo/components/style/properties_and_values/rule.rs
2023-11-24 08:57:14 +01:00

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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at https://mozilla.org/MPL/2.0/. */
//! The [`@property`] at-rule.
//!
//! https://drafts.css-houdini.org/css-properties-values-api-1/#at-property-rule
use crate::custom_properties::{Name as CustomPropertyName, SpecifiedValue};
use crate::error_reporting::ContextualParseError;
use crate::parser::{Parse, ParserContext};
use crate::properties_and_values::syntax::Descriptor as SyntaxDescriptor;
use crate::shared_lock::{SharedRwLockReadGuard, ToCssWithGuard};
use crate::str::CssStringWriter;
use crate::values::serialize_atom_name;
use cssparser::{
AtRuleParser, CowRcStr, DeclarationParser, ParseErrorKind, Parser, QualifiedRuleParser,
RuleBodyItemParser, RuleBodyParser, SourceLocation,
};
#[cfg(feature = "gecko")]
use malloc_size_of::{MallocSizeOf, MallocSizeOfOps};
use selectors::parser::SelectorParseErrorKind;
use servo_arc::Arc;
use std::fmt::{self, Write};
use style_traits::{CssWriter, ParseError, StyleParseErrorKind, ToCss};
use to_shmem::{SharedMemoryBuilder, ToShmem};
/// Parse the block inside a `@property` rule.
///
/// Valid `@property` rules result in a registered custom property, as if `registerProperty()` had
/// been called with equivalent parameters.
pub fn parse_property_block(
context: &ParserContext,
input: &mut Parser,
name: PropertyRuleName,
location: SourceLocation,
) -> PropertyRuleData {
let mut rule = PropertyRuleData::empty(name, location);
let mut parser = PropertyRuleParser {
context,
rule: &mut rule,
};
let mut iter = RuleBodyParser::new(input, &mut parser);
while let Some(declaration) = iter.next() {
if !context.error_reporting_enabled() {
continue;
}
if let Err((error, slice)) = declaration {
let location = error.location;
let error = if matches!(
error.kind,
ParseErrorKind::Custom(StyleParseErrorKind::PropertySyntaxField(_))
) {
ContextualParseError::UnsupportedValue(slice, error)
} else {
ContextualParseError::UnsupportedPropertyDescriptor(slice, error)
};
context.log_css_error(location, error);
}
}
rule
}
struct PropertyRuleParser<'a, 'b: 'a> {
context: &'a ParserContext<'b>,
rule: &'a mut PropertyRuleData,
}
/// Default methods reject all at rules.
impl<'a, 'b, 'i> AtRuleParser<'i> for PropertyRuleParser<'a, 'b> {
type Prelude = ();
type AtRule = ();
type Error = StyleParseErrorKind<'i>;
}
impl<'a, 'b, 'i> QualifiedRuleParser<'i> for PropertyRuleParser<'a, 'b> {
type Prelude = ();
type QualifiedRule = ();
type Error = StyleParseErrorKind<'i>;
}
impl<'a, 'b, 'i> RuleBodyItemParser<'i, (), StyleParseErrorKind<'i>>
for PropertyRuleParser<'a, 'b>
{
fn parse_qualified(&self) -> bool {
false
}
fn parse_declarations(&self) -> bool {
true
}
}
macro_rules! property_descriptors {
(
$( #[$doc: meta] $name: tt $ident: ident: $ty: ty, )*
) => {
/// Data inside a `@property` rule.
///
/// <https://drafts.css-houdini.org/css-properties-values-api-1/#at-property-rule>
#[derive(Clone, Debug, PartialEq)]
pub struct PropertyRuleData {
/// The custom property name.
pub name: PropertyRuleName,
$(
#[$doc]
pub $ident: Option<$ty>,
)*
/// Line and column of the @property rule source code.
pub source_location: SourceLocation,
}
impl PropertyRuleData {
/// Create an empty property rule
pub fn empty(name: PropertyRuleName, source_location: SourceLocation) -> Self {
PropertyRuleData {
name,
$(
$ident: None,
)*
source_location,
}
}
/// Serialization of declarations in PropertyRuleData
pub fn decl_to_css(&self, dest: &mut CssStringWriter) -> fmt::Result {
$(
if let Some(ref value) = self.$ident {
dest.write_str(concat!($name, ": "))?;
value.to_css(&mut CssWriter::new(dest))?;
dest.write_str("; ")?;
}
)*
Ok(())
}
}
impl<'a, 'b, 'i> DeclarationParser<'i> for PropertyRuleParser<'a, 'b> {
type Declaration = ();
type Error = StyleParseErrorKind<'i>;
fn parse_value<'t>(
&mut self,
name: CowRcStr<'i>,
input: &mut Parser<'i, 't>,
) -> Result<(), ParseError<'i>> {
match_ignore_ascii_case! { &*name,
$(
$name => {
// DeclarationParser also calls parse_entirely so wed normally not need
// to, but in this case we do because we set the value as a side effect
// rather than returning it.
let value = input.parse_entirely(|i| Parse::parse(self.context, i))?;
self.rule.$ident = Some(value)
},
)*
_ => return Err(input.new_custom_error(SelectorParseErrorKind::UnexpectedIdent(name.clone()))),
}
Ok(())
}
}
}
}
property_descriptors! {
/// <https://drafts.css-houdini.org/css-properties-values-api-1/#the-syntax-descriptor>
"syntax" syntax: SyntaxDescriptor,
/// <https://drafts.css-houdini.org/css-properties-values-api-1/#inherits-descriptor>
"inherits" inherits: Inherits,
/// <https://drafts.css-houdini.org/css-properties-values-api-1/#initial-value-descriptor>
"initial-value" initial_value: InitialValue,
}
impl PropertyRuleData {
/// Measure heap usage.
#[cfg(feature = "gecko")]
pub fn size_of(&self, _guard: &SharedRwLockReadGuard, ops: &mut MallocSizeOfOps) -> usize {
self.name.0.size_of(ops) +
self.syntax.size_of(ops) +
self.inherits.size_of(ops) +
if let Some(ref initial_value) = self.initial_value {
initial_value.size_of(ops)
} else {
0
}
}
}
impl ToCssWithGuard for PropertyRuleData {
/// <https://drafts.css-houdini.org/css-properties-values-api-1/#serialize-a-csspropertyrule>
fn to_css(&self, _guard: &SharedRwLockReadGuard, dest: &mut CssStringWriter) -> fmt::Result {
dest.write_str("@property ")?;
self.name.to_css(&mut CssWriter::new(dest))?;
dest.write_str(" { ")?;
self.decl_to_css(dest)?;
dest.write_char('}')
}
}
impl ToShmem for PropertyRuleData {
fn to_shmem(&self, _builder: &mut SharedMemoryBuilder) -> to_shmem::Result<Self> {
Err(String::from(
"ToShmem failed for PropertyRule: cannot handle @property rules",
))
}
}
/// A custom property name wrapper that includes the `--` prefix in its serialization
#[derive(Clone, Debug, PartialEq)]
pub struct PropertyRuleName(pub Arc<CustomPropertyName>);
impl ToCss for PropertyRuleName {
fn to_css<W: Write>(&self, dest: &mut CssWriter<W>) -> fmt::Result {
dest.write_str("--")?;
serialize_atom_name(&self.0, dest)
}
}
/// <https://drafts.css-houdini.org/css-properties-values-api-1/#inherits-descriptor>
#[derive(Clone, Debug, MallocSizeOf, Parse, PartialEq, ToCss)]
pub enum Inherits {
/// `true` value for the `inherits` descriptor
True,
/// `false` value for the `inherits` descriptor
False,
}
/// Specifies the initial value of the custom property registration represented by the @property
/// rule, controlling the propertys initial value.
///
/// The SpecifiedValue is wrapped in an Arc to avoid copying when using it.
pub type InitialValue = Arc<SpecifiedValue>;
impl Parse for InitialValue {
fn parse<'i, 't>(
_context: &ParserContext,
input: &mut Parser<'i, 't>,
) -> Result<Self, ParseError<'i>> {
input.skip_whitespace();
SpecifiedValue::parse(input)
}
}