/
supports_rule.rs
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/
supports_rule.rs
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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 http://mozilla.org/MPL/2.0/. */
//! [@supports rules](https://drafts.csswg.org/css-conditional-3/#at-supports)
use cssparser::{BasicParseError, ParseError as CssParseError, ParserInput};
use cssparser::{Delimiter, parse_important, Parser, SourceLocation, Token};
#[cfg(feature = "gecko")]
use malloc_size_of::{MallocSizeOfOps, MallocUnconditionalShallowSizeOf};
use parser::ParserContext;
use properties::{PropertyId, PropertyDeclaration, PropertyParserContext, SourcePropertyDeclaration};
use selectors::parser::SelectorParseError;
use servo_arc::Arc;
use shared_lock::{DeepCloneParams, DeepCloneWithLock, Locked, SharedRwLock, SharedRwLockReadGuard, ToCssWithGuard};
use std::fmt;
use style_traits::{ToCss, ParseError, StyleParseError};
use stylesheets::{CssRuleType, CssRules};
/// An [`@supports`][supports] rule.
///
/// [supports]: https://drafts.csswg.org/css-conditional-3/#at-supports
#[derive(Debug)]
pub struct SupportsRule {
/// The parsed condition
pub condition: SupportsCondition,
/// Child rules
pub rules: Arc<Locked<CssRules>>,
/// The result of evaluating the condition
pub enabled: bool,
/// The line and column of the rule's source code.
pub source_location: SourceLocation,
}
impl SupportsRule {
/// Measure heap usage.
#[cfg(feature = "gecko")]
pub fn size_of(&self, guard: &SharedRwLockReadGuard, ops: &mut MallocSizeOfOps) -> usize {
// Measurement of other fields may be added later.
self.rules.unconditional_shallow_size_of(ops) +
self.rules.read_with(guard).size_of(guard, ops)
}
}
impl ToCssWithGuard for SupportsRule {
fn to_css<W>(&self, guard: &SharedRwLockReadGuard, dest: &mut W) -> fmt::Result
where W: fmt::Write {
dest.write_str("@supports ")?;
self.condition.to_css(dest)?;
dest.write_str(" {")?;
for rule in self.rules.read_with(guard).0.iter() {
dest.write_str(" ")?;
rule.to_css(guard, dest)?;
}
dest.write_str(" }")
}
}
impl DeepCloneWithLock for SupportsRule {
fn deep_clone_with_lock(
&self,
lock: &SharedRwLock,
guard: &SharedRwLockReadGuard,
params: &DeepCloneParams,
) -> Self {
let rules = self.rules.read_with(guard);
SupportsRule {
condition: self.condition.clone(),
rules: Arc::new(lock.wrap(rules.deep_clone_with_lock(lock, guard, params))),
enabled: self.enabled,
source_location: self.source_location.clone(),
}
}
}
/// An @supports condition
///
/// https://drafts.csswg.org/css-conditional-3/#at-supports
#[derive(Clone, Debug)]
pub enum SupportsCondition {
/// `not (condition)`
Not(Box<SupportsCondition>),
/// `(condition)`
Parenthesized(Box<SupportsCondition>),
/// `(condition) and (condition) and (condition) ..`
And(Vec<SupportsCondition>),
/// `(condition) or (condition) or (condition) ..`
Or(Vec<SupportsCondition>),
/// `property-ident: value` (value can be any tokens)
Declaration(Declaration),
/// `(any tokens)` or `func(any tokens)`
FutureSyntax(String),
}
impl SupportsCondition {
/// Parse a condition
///
/// https://drafts.csswg.org/css-conditional/#supports_condition
pub fn parse<'i, 't>(input: &mut Parser<'i, 't>) -> Result<SupportsCondition, ParseError<'i>> {
if let Ok(_) = input.try(|i| i.expect_ident_matching("not")) {
let inner = SupportsCondition::parse_in_parens(input)?;
return Ok(SupportsCondition::Not(Box::new(inner)));
}
let in_parens = SupportsCondition::parse_in_parens(input)?;
let (keyword, wrapper) = match input.next() {
Err(_) => {
// End of input
return Ok(in_parens)
}
Ok(&Token::Ident(ref ident)) => {
match_ignore_ascii_case! { &ident,
"and" => ("and", SupportsCondition::And as fn(_) -> _),
"or" => ("or", SupportsCondition::Or as fn(_) -> _),
_ => return Err(SelectorParseError::UnexpectedIdent(ident.clone()).into())
}
}
Ok(t) => return Err(CssParseError::Basic(BasicParseError::UnexpectedToken(t.clone())))
};
let mut conditions = Vec::with_capacity(2);
conditions.push(in_parens);
loop {
conditions.push(SupportsCondition::parse_in_parens(input)?);
if input.try(|input| input.expect_ident_matching(keyword)).is_err() {
// Did not find the expected keyword.
// If we found some other token,
// it will be rejected by `Parser::parse_entirely` somewhere up the stack.
return Ok(wrapper(conditions))
}
}
}
/// https://drafts.csswg.org/css-conditional-3/#supports_condition_in_parens
fn parse_in_parens<'i, 't>(input: &mut Parser<'i, 't>) -> Result<SupportsCondition, ParseError<'i>> {
// Whitespace is normally taken care of in `Parser::next`,
// but we want to not include it in `pos` for the SupportsCondition::FutureSyntax cases.
while input.try(Parser::expect_whitespace).is_ok() {}
let pos = input.position();
// FIXME: remove clone() when lifetimes are non-lexical
match input.next()?.clone() {
Token::ParenthesisBlock => {
let nested = input.try(|input| {
input.parse_nested_block(|i| parse_condition_or_declaration(i))
});
if nested.is_ok() {
return nested;
}
}
Token::Function(_) => {}
t => return Err(CssParseError::Basic(BasicParseError::UnexpectedToken(t))),
}
input.parse_nested_block(|i| consume_any_value(i))?;
Ok(SupportsCondition::FutureSyntax(input.slice_from(pos).to_owned()))
}
/// Evaluate a supports condition
pub fn eval(&self, cx: &ParserContext) -> bool {
match *self {
SupportsCondition::Not(ref cond) => !cond.eval(cx),
SupportsCondition::Parenthesized(ref cond) => cond.eval(cx),
SupportsCondition::And(ref vec) => vec.iter().all(|c| c.eval(cx)),
SupportsCondition::Or(ref vec) => vec.iter().any(|c| c.eval(cx)),
SupportsCondition::Declaration(ref decl) => decl.eval(cx),
SupportsCondition::FutureSyntax(_) => false
}
}
}
/// supports_condition | declaration
/// https://drafts.csswg.org/css-conditional/#dom-css-supports-conditiontext-conditiontext
pub fn parse_condition_or_declaration<'i, 't>(input: &mut Parser<'i, 't>)
-> Result<SupportsCondition, ParseError<'i>> {
if let Ok(condition) = input.try(SupportsCondition::parse) {
Ok(SupportsCondition::Parenthesized(Box::new(condition)))
} else {
Declaration::parse(input).map(SupportsCondition::Declaration)
}
}
impl ToCss for SupportsCondition {
fn to_css<W>(&self, dest: &mut W) -> fmt::Result
where W: fmt::Write,
{
match *self {
SupportsCondition::Not(ref cond) => {
dest.write_str("not ")?;
cond.to_css(dest)
}
SupportsCondition::Parenthesized(ref cond) => {
dest.write_str("(")?;
cond.to_css(dest)?;
dest.write_str(")")
}
SupportsCondition::And(ref vec) => {
let mut first = true;
for cond in vec {
if !first {
dest.write_str(" and ")?;
}
first = false;
cond.to_css(dest)?;
}
Ok(())
}
SupportsCondition::Or(ref vec) => {
let mut first = true;
for cond in vec {
if !first {
dest.write_str(" or ")?;
}
first = false;
cond.to_css(dest)?;
}
Ok(())
}
SupportsCondition::Declaration(ref decl) => {
dest.write_str("(")?;
decl.to_css(dest)?;
dest.write_str(")")
}
SupportsCondition::FutureSyntax(ref s) => dest.write_str(&s),
}
}
}
#[derive(Clone, Debug)]
/// A possibly-invalid property declaration
pub struct Declaration(pub String);
impl ToCss for Declaration {
fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
dest.write_str(&self.0)
}
}
/// https://drafts.csswg.org/css-syntax-3/#typedef-any-value
fn consume_any_value<'i, 't>(input: &mut Parser<'i, 't>) -> Result<(), ParseError<'i>> {
input.expect_no_error_token().map_err(|err| err.into())
}
impl Declaration {
/// Parse a declaration
pub fn parse<'i, 't>(input: &mut Parser<'i, 't>) -> Result<Declaration, ParseError<'i>> {
let pos = input.position();
input.expect_ident()?;
input.expect_colon()?;
consume_any_value(input)?;
Ok(Declaration(input.slice_from(pos).to_owned()))
}
/// Determine if a declaration parses
///
/// https://drafts.csswg.org/css-conditional-3/#support-definition
pub fn eval(&self, context: &ParserContext) -> bool {
debug_assert_eq!(context.rule_type(), CssRuleType::Style);
let mut input = ParserInput::new(&self.0);
let mut input = Parser::new(&mut input);
input.parse_entirely(|input| {
let prop = input.expect_ident().unwrap().as_ref().to_owned();
input.expect_colon().unwrap();
let property_context = PropertyParserContext::new(&context);
let id = PropertyId::parse(&prop, Some(&property_context))
.map_err(|_| StyleParseError::UnspecifiedError)?;
let mut declarations = SourcePropertyDeclaration::new();
input.parse_until_before(Delimiter::Bang, |input| {
PropertyDeclaration::parse_into(&mut declarations, id, prop.into(), &context, input)
.map_err(|e| StyleParseError::PropertyDeclaration(e).into())
})?;
let _ = input.try(parse_important);
Ok(())
}).is_ok()
}
}