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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
//! A [`@layer`][layer] rule.
//!
use crate::parser::{Parse, ParserContext};
use crate::shared_lock::{DeepCloneWithLock, Locked};
use crate::shared_lock::{SharedRwLock, SharedRwLockReadGuard, ToCssWithGuard};
use crate::values::AtomIdent;
use super::CssRules;
use cssparser::{Parser, SourceLocation, Token};
use servo_arc::Arc;
use smallvec::SmallVec;
use std::fmt::{self, Write};
use style_traits::{CssWriter, ParseError, ToCss};
/// The order of a given layer. We use 16 bits so that we can pack LayerOrder
/// and CascadeLevel in a single 32-bit struct. If we need more bits we can go
/// back to packing CascadeLevel in a single byte as we did before.
#[derive(Clone, Copy, Debug, Eq, Hash, MallocSizeOf, PartialEq, PartialOrd, Ord)]
pub struct LayerOrder(u16);
impl LayerOrder {
/// The order of the root layer.
pub const fn root() -> Self {
Self(std::u16::MAX - 1)
}
/// The order of the style attribute layer.
pub const fn style_attribute() -> Self {
Self(std::u16::MAX)
}
/// Returns whether this layer is for the style attribute, which behaves
/// differently in terms of !important, see
///
/// (This is a bit silly, mind-you, but it's needed so that revert-layer
/// behaves correctly).
#[inline]
pub fn is_style_attribute_layer(&self) -> bool {
*self == Self::style_attribute()
}
/// The first cascade layer order.
pub const fn first() -> Self {
Self(0)
}
/// Increment the cascade layer order.
#[inline]
pub fn inc(&mut self) {
if self.0 != std::u16::MAX - 1 {
self.0 += 1;
}
}
}
#[derive(Clone, Debug, Eq, Hash, MallocSizeOf, PartialEq, ToShmem)]
pub struct LayerName(pub SmallVec<[AtomIdent; 1]>);
impl LayerName {
/// Returns an empty layer name (which isn't a valid final state, so caller
/// is responsible to fill up the name before use).
pub fn new_empty() -> Self {
Self(Default::default())
}
/// Returns a synthesized name for an anonymous layer.
pub fn new_anonymous() -> Self {
use std::sync::atomic::{AtomicUsize, Ordering};
static NEXT_ANONYMOUS_LAYER_NAME: AtomicUsize = AtomicUsize::new(0);
let mut name = SmallVec::new();
let next_id = NEXT_ANONYMOUS_LAYER_NAME.fetch_add(1, Ordering::Relaxed);
// The parens don't _technically_ prevent conflicts with authors, as
// authors could write escaped parens as part of the identifier, I
// think, but highly reduces the possibility.
name.push(AtomIdent::from(&*format!("-moz-anon-layer({})", next_id)));
LayerName(name)
}
/// Returns the names of the layers. That is, for a layer like `foo.bar`,
/// it'd return [foo, bar].
pub fn layer_names(&self) -> &[AtomIdent] {
&self.0
}
}
impl Parse for LayerName {
fn parse<'i, 't>(
_: &ParserContext,
input: &mut Parser<'i, 't>,
) -> Result<Self, ParseError<'i>> {
let mut result = SmallVec::new();
result.push(AtomIdent::from(&**input.expect_ident()?));
loop {
let next_name = input.try_parse(|input| -> Result<AtomIdent, ParseError<'i>> {
match input.next_including_whitespace()? {
Token::Delim('.') => {},
other => {
let t = other.clone();
return Err(input.new_unexpected_token_error(t));
},
}
let name = match input.next_including_whitespace()? {
Token::Ident(ref ident) => ident,
other => {
let t = other.clone();
return Err(input.new_unexpected_token_error(t));
},
};
Ok(AtomIdent::from(&**name))
});
match next_name {
Ok(name) => result.push(name),
Err(..) => break,
}
}
Ok(LayerName(result))
}
}
impl ToCss for LayerName {
fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
where
W: Write,
{
let mut first = true;
for name in self.0.iter() {
if !first {
dest.write_char('.')?;
}
first = false;
name.to_css(dest)?;
}
Ok(())
}
}
#[derive(Debug, ToShmem)]
/// A block `@layer <name>? { ... }`
pub struct LayerBlockRule {
/// The layer name, or `None` if anonymous.
pub name: Option<LayerName>,
/// The nested rules.
pub rules: Arc<Locked<CssRules>>,
/// The source position where this rule was found.
pub source_location: SourceLocation,
}
impl ToCssWithGuard for LayerBlockRule {
fn to_css(
&self,
guard: &SharedRwLockReadGuard,
dest: &mut style_traits::CssStringWriter,
) -> fmt::Result {
dest.write_str("@layer")?;
if let Some(ref name) = self.name {
dest.write_char(' ')?;
name.to_css(&mut CssWriter::new(dest))?;
}
self.rules.read_with(guard).to_css_block(guard, dest)
}
}
impl DeepCloneWithLock for LayerBlockRule {
fn deep_clone_with_lock(&self, lock: &SharedRwLock, guard: &SharedRwLockReadGuard) -> Self {
Self {
name: self.name.clone(),
rules: Arc::new(
lock.wrap(
self.rules
.read_with(guard)
.deep_clone_with_lock(lock, guard),
),
),
source_location: self.source_location.clone(),
}
}
}
/// A statement `@layer <name>, <name>, <name>;`
///
#[derive(Clone, Debug, ToShmem)]
pub struct LayerStatementRule {
/// The list of layers to sort.
pub names: Vec<LayerName>,
/// The source position where this rule was found.
pub source_location: SourceLocation,
}
impl ToCssWithGuard for LayerStatementRule {
fn to_css(
&self,
_: &SharedRwLockReadGuard,
dest: &mut style_traits::CssStringWriter,
) -> fmt::Result {
let mut writer = CssWriter::new(dest);
writer.write_str("@layer ")?;
let mut first = true;
for name in &*self.names {
if !first {
writer.write_str(", ")?;
}
first = false;
name.to_css(&mut writer)?;
}
writer.write_char(';')
}
}