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85d19a99d2
The idea here is having (for convenience) different `Expression` and `Device` representations for Gecko. Both will be implemented in rust, but will use `nsMediaFeatures` as a source of media features instead of the Servo bits. Does it sound good? r? @heycam or @Manishearth Source-Repo: https://github.com/servo/servo Source-Revision: fdddeb1c9229b6f9bc202cb2df1a3701eec47e05
303 lines
9.3 KiB
Rust
303 lines
9.3 KiB
Rust
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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//! [Media queries][mq].
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//!
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//! [mq]: https://drafts.csswg.org/mediaqueries/
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use Atom;
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use cssparser::{Delimiter, Parser, Token};
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use serialize_comma_separated_list;
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use std::ascii::AsciiExt;
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use std::fmt;
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use style_traits::ToCss;
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#[cfg(feature = "servo")]
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pub use servo::media_queries::{Device, Expression};
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#[cfg(feature = "gecko")]
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pub use gecko::media_queries::{Device, Expression};
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/// A type that encapsulates a media query list.
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#[derive(Debug, PartialEq)]
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#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
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pub struct MediaList {
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/// The list of media queries.
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pub media_queries: Vec<MediaQuery>
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}
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impl ToCss for MediaList {
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fn to_css<W>(&self, dest: &mut W) -> fmt::Result
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where W: fmt::Write
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{
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serialize_comma_separated_list(dest, &self.media_queries)
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}
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}
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impl Default for MediaList {
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fn default() -> MediaList {
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MediaList { media_queries: vec![] }
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}
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}
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/// https://drafts.csswg.org/mediaqueries/#mq-prefix
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#[derive(PartialEq, Eq, Copy, Clone, Debug)]
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#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
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pub enum Qualifier {
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/// Hide a media query from legacy UAs:
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/// https://drafts.csswg.org/mediaqueries/#mq-only
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Only,
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/// Negate a media query:
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/// https://drafts.csswg.org/mediaqueries/#mq-not
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Not,
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}
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impl ToCss for Qualifier {
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fn to_css<W>(&self, dest: &mut W) -> fmt::Result
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where W: fmt::Write
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{
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match *self {
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Qualifier::Not => write!(dest, "not"),
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Qualifier::Only => write!(dest, "only"),
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}
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}
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}
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/// A [media query][mq].
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///
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/// [mq]: https://drafts.csswg.org/mediaqueries/
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#[derive(Clone, Debug, PartialEq)]
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#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
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pub struct MediaQuery {
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/// The qualifier for this query.
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pub qualifier: Option<Qualifier>,
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/// The media type for this query, that can be known, unknown, or "all".
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pub media_type: MediaQueryType,
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/// The set of expressions that this media query contains.
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pub expressions: Vec<Expression>,
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}
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impl MediaQuery {
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/// Return a media query that never matches, used for when we fail to parse
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/// a given media query.
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fn never_matching() -> Self {
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Self::new(Some(Qualifier::Not), MediaQueryType::All, vec![])
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}
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/// Trivially constructs a new media query.
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pub fn new(qualifier: Option<Qualifier>,
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media_type: MediaQueryType,
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expressions: Vec<Expression>) -> MediaQuery {
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MediaQuery {
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qualifier: qualifier,
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media_type: media_type,
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expressions: expressions,
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}
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}
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}
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impl ToCss for MediaQuery {
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fn to_css<W>(&self, dest: &mut W) -> fmt::Result
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where W: fmt::Write,
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{
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if let Some(qual) = self.qualifier {
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try!(qual.to_css(dest));
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try!(write!(dest, " "));
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}
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match self.media_type {
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MediaQueryType::All => {
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// We need to print "all" if there's a qualifier, or there's
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// just an empty list of expressions.
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//
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// Otherwise, we'd serialize media queries like "(min-width:
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// 40px)" in "all (min-width: 40px)", which is unexpected.
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if self.qualifier.is_some() || self.expressions.is_empty() {
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try!(write!(dest, "all"));
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}
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},
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MediaQueryType::Known(MediaType::Screen) => try!(write!(dest, "screen")),
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MediaQueryType::Known(MediaType::Print) => try!(write!(dest, "print")),
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MediaQueryType::Unknown(ref desc) => try!(write!(dest, "{}", desc)),
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}
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if self.expressions.is_empty() {
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return Ok(());
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}
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if self.media_type != MediaQueryType::All || self.qualifier.is_some() {
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try!(write!(dest, " and "));
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}
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try!(self.expressions[0].to_css(dest));
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for expr in self.expressions.iter().skip(1) {
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try!(write!(dest, " and "));
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try!(expr.to_css(dest));
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}
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Ok(())
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}
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}
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/// http://dev.w3.org/csswg/mediaqueries-3/#media0
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#[derive(PartialEq, Eq, Clone, Debug)]
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#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
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pub enum MediaQueryType {
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/// A media type that matches every device.
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All,
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/// A known media type, that we parse and understand.
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Known(MediaType),
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/// An unknown media type.
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Unknown(Atom),
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}
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impl MediaQueryType {
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fn parse(ident: &str) -> Self {
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if ident.eq_ignore_ascii_case("all") {
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return MediaQueryType::All;
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}
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match MediaType::parse(ident) {
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Some(media_type) => MediaQueryType::Known(media_type),
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None => MediaQueryType::Unknown(Atom::from(ident)),
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}
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}
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fn matches(&self, other: MediaType) -> bool {
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match *self {
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MediaQueryType::All => true,
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MediaQueryType::Known(ref known_type) => *known_type == other,
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MediaQueryType::Unknown(..) => false,
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}
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}
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}
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/// https://drafts.csswg.org/mediaqueries/#media-types
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#[derive(PartialEq, Eq, Clone, Debug)]
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#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
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pub enum MediaType {
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/// The "screen" media type.
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Screen,
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/// The "print" media type.
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Print,
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}
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impl MediaType {
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fn parse(name: &str) -> Option<Self> {
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Some(match_ignore_ascii_case! { name,
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"screen" => MediaType::Screen,
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"print" => MediaType::Print,
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_ => return None
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})
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}
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}
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impl MediaQuery {
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/// Parse a media query given css input.
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///
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/// Returns an error if any of the expressions is unknown.
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pub fn parse(input: &mut Parser) -> Result<MediaQuery, ()> {
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let mut expressions = vec![];
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let qualifier = if input.try(|input| input.expect_ident_matching("only")).is_ok() {
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Some(Qualifier::Only)
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} else if input.try(|input| input.expect_ident_matching("not")).is_ok() {
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Some(Qualifier::Not)
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} else {
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None
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};
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let media_type = match input.try(|input| input.expect_ident()) {
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Ok(ident) => MediaQueryType::parse(&*ident),
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Err(()) => {
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// Media type is only optional if qualifier is not specified.
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if qualifier.is_some() {
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return Err(())
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}
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// Without a media type, require at least one expression.
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expressions.push(try!(Expression::parse(input)));
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MediaQueryType::All
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}
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};
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// Parse any subsequent expressions
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loop {
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if input.try(|input| input.expect_ident_matching("and")).is_err() {
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return Ok(MediaQuery::new(qualifier, media_type, expressions))
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}
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expressions.push(try!(Expression::parse(input)))
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}
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}
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}
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/// Parse a media query list from CSS.
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///
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/// Always returns a media query list. If any invalid media query is found, the
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/// media query list is only filled with the equivalent of "not all", see:
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///
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/// https://drafts.csswg.org/mediaqueries/#error-handling
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pub fn parse_media_query_list(input: &mut Parser) -> MediaList {
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if input.is_exhausted() {
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return Default::default()
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}
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let mut media_queries = vec![];
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let mut found_invalid = false;
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loop {
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match input.parse_until_before(Delimiter::Comma, MediaQuery::parse) {
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Ok(mq) => if !found_invalid {
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media_queries.push(mq);
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},
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Err(..) => if !found_invalid {
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media_queries.clear();
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media_queries.push(MediaQuery::never_matching());
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// Consume the rest of the input as if they were valid
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// expressions (they might be, they might not), but ignore the
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// result, this allows correctly parsing invalid media queries.
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found_invalid = true;
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},
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}
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match input.next() {
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Ok(Token::Comma) => {},
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Ok(_) => unreachable!(),
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Err(()) => break,
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}
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}
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debug_assert!(!found_invalid || media_queries.len() == 1);
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MediaList {
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media_queries: media_queries,
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}
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}
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impl MediaList {
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/// Evaluate a whole `MediaList` against `Device`.
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pub fn evaluate(&self, device: &Device) -> bool {
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// Check if it is an empty media query list or any queries match (OR condition)
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// https://drafts.csswg.org/mediaqueries-4/#mq-list
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self.media_queries.is_empty() || self.media_queries.iter().any(|mq| {
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let media_match = mq.media_type.matches(device.media_type());
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// Check if all conditions match (AND condition)
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let query_match =
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media_match &&
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mq.expressions.iter()
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.all(|expression| expression.matches(&device));
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// Apply the logical NOT qualifier to the result
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match mq.qualifier {
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Some(Qualifier::Not) => !query_match,
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_ => query_match,
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}
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})
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}
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/// Whether this `MediaList` contains no media queries.
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pub fn is_empty(&self) -> bool {
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self.media_queries.is_empty()
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}
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}
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