style: Move media_queries module to be a directory.

Bug: 1468846
Reviewed-by: xidorn
MozReview-Commit-ID: 7H93L6f0bAl

components/style/media_queries/mod.rs

@@ -0,0 +1,349 @@
+/* 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/. */
+
+//! [Media queries][mq].
+//!
+//! [mq]: https://drafts.csswg.org/mediaqueries/
+
+use Atom;
+use context::QuirksMode;
+use cssparser::{Delimiter, Parser};
+use cssparser::{ParserInput, Token};
+use error_reporting::{ContextualParseError, ParseErrorReporter};
+use parser::{ParserContext, ParserErrorContext};
+use selectors::parser::SelectorParseErrorKind;
+use std::fmt::{self, Write};
+use str::string_as_ascii_lowercase;
+use style_traits::{CssWriter, ParseError, StyleParseErrorKind, ToCss};
+use values::CustomIdent;
+
+#[cfg(feature = "servo")]
+pub use servo::media_queries::{Device, Expression};
+#[cfg(feature = "gecko")]
+pub use gecko::media_queries::{Device, Expression};
+
+/// A type that encapsulates a media query list.
+#[css(comma)]
+#[derive(Clone, Debug, MallocSizeOf, ToCss)]
+pub struct MediaList {
+    /// The list of media queries.
+    #[css(iterable)]
+    pub media_queries: Vec<MediaQuery>,
+}
+
+impl MediaList {
+    /// Create an empty MediaList.
+    pub fn empty() -> Self {
+        MediaList {
+            media_queries: vec![],
+        }
+    }
+}
+
+/// <https://drafts.csswg.org/mediaqueries/#mq-prefix>
+#[derive(Clone, Copy, Debug, Eq, MallocSizeOf, PartialEq, ToCss)]
+pub enum Qualifier {
+    /// Hide a media query from legacy UAs:
+    /// <https://drafts.csswg.org/mediaqueries/#mq-only>
+    Only,
+    /// Negate a media query:
+    /// <https://drafts.csswg.org/mediaqueries/#mq-not>
+    Not,
+}
+
+/// A [media query][mq].
+///
+/// [mq]: https://drafts.csswg.org/mediaqueries/
+#[derive(Clone, Debug, MallocSizeOf, PartialEq)]
+pub struct MediaQuery {
+    /// The qualifier for this query.
+    pub qualifier: Option<Qualifier>,
+    /// The media type for this query, that can be known, unknown, or "all".
+    pub media_type: MediaQueryType,
+    /// The set of expressions that this media query contains.
+    pub expressions: Vec<Expression>,
+}
+
+impl MediaQuery {
+    /// Return a media query that never matches, used for when we fail to parse
+    /// a given media query.
+    fn never_matching() -> Self {
+        Self {
+            qualifier: Some(Qualifier::Not),
+            media_type: MediaQueryType::All,
+            expressions: vec![],
+        }
+    }
+}
+
+impl ToCss for MediaQuery {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
+        if let Some(qual) = self.qualifier {
+            qual.to_css(dest)?;
+            dest.write_char(' ')?;
+        }
+
+        match self.media_type {
+            MediaQueryType::All => {
+                // We need to print "all" if there's a qualifier, or there's
+                // just an empty list of expressions.
+                //
+                // Otherwise, we'd serialize media queries like "(min-width:
+                // 40px)" in "all (min-width: 40px)", which is unexpected.
+                if self.qualifier.is_some() || self.expressions.is_empty() {
+                    dest.write_str("all")?;
+                }
+            },
+            MediaQueryType::Concrete(MediaType(ref desc)) => desc.to_css(dest)?,
+        }
+
+        if self.expressions.is_empty() {
+            return Ok(());
+        }
+
+        if self.media_type != MediaQueryType::All || self.qualifier.is_some() {
+            dest.write_str(" and ")?;
+        }
+
+        self.expressions[0].to_css(dest)?;
+
+        for expr in self.expressions.iter().skip(1) {
+            dest.write_str(" and ")?;
+            expr.to_css(dest)?;
+        }
+        Ok(())
+    }
+}
+
+/// <http://dev.w3.org/csswg/mediaqueries-3/#media0>
+#[derive(Clone, Debug, Eq, MallocSizeOf, PartialEq)]
+pub enum MediaQueryType {
+    /// A media type that matches every device.
+    All,
+    /// A specific media type.
+    Concrete(MediaType),
+}
+
+impl MediaQueryType {
+    fn parse(ident: &str) -> Result<Self, ()> {
+        match_ignore_ascii_case! { ident,
+            "all" => return Ok(MediaQueryType::All),
+            _ => (),
+        };
+
+        // If parseable, accept this type as a concrete type.
+        MediaType::parse(ident).map(MediaQueryType::Concrete)
+    }
+
+    fn matches(&self, other: MediaType) -> bool {
+        match *self {
+            MediaQueryType::All => true,
+            MediaQueryType::Concrete(ref known_type) => *known_type == other,
+        }
+    }
+}
+
+/// <https://drafts.csswg.org/mediaqueries/#media-types>
+#[derive(Clone, Debug, Eq, MallocSizeOf, PartialEq)]
+pub struct MediaType(pub CustomIdent);
+
+impl MediaType {
+    /// The `screen` media type.
+    pub fn screen() -> Self {
+        MediaType(CustomIdent(atom!("screen")))
+    }
+
+    /// The `print` media type.
+    pub fn print() -> Self {
+        MediaType(CustomIdent(atom!("print")))
+    }
+
+    fn parse(name: &str) -> Result<Self, ()> {
+        // From https://drafts.csswg.org/mediaqueries/#mq-syntax:
+        //
+        //   The <media-type> production does not include the keywords not, or, and, and only.
+        //
+        // Here we also perform the to-ascii-lowercase part of the serialization
+        // algorithm: https://drafts.csswg.org/cssom/#serializing-media-queries
+        match_ignore_ascii_case! { name,
+            "not" | "or" | "and" | "only" => Err(()),
+            _ => Ok(MediaType(CustomIdent(Atom::from(string_as_ascii_lowercase(name))))),
+        }
+    }
+}
+
+impl MediaQuery {
+    /// Parse a media query given css input.
+    ///
+    /// Returns an error if any of the expressions is unknown.
+    pub fn parse<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+    ) -> Result<MediaQuery, ParseError<'i>> {
+        let mut expressions = vec![];
+
+        let qualifier = if input
+            .try(|input| input.expect_ident_matching("only"))
+            .is_ok()
+        {
+            Some(Qualifier::Only)
+        } else if input
+            .try(|input| input.expect_ident_matching("not"))
+            .is_ok()
+        {
+            Some(Qualifier::Not)
+        } else {
+            None
+        };
+
+        let media_type = match input.try(|i| i.expect_ident_cloned()) {
+            Ok(ident) => MediaQueryType::parse(&*ident).map_err(|()| {
+                input.new_custom_error(SelectorParseErrorKind::UnexpectedIdent(ident.clone()))
+            })?,
+            Err(_) => {
+                // Media type is only optional if qualifier is not specified.
+                if qualifier.is_some() {
+                    return Err(input.new_custom_error(StyleParseErrorKind::UnspecifiedError));
+                }
+
+                // Without a media type, require at least one expression.
+                expressions.push(Expression::parse(context, input)?);
+
+                MediaQueryType::All
+            },
+        };
+
+        // Parse any subsequent expressions
+        loop {
+            if input
+                .try(|input| input.expect_ident_matching("and"))
+                .is_err()
+            {
+                return Ok(MediaQuery {
+                    qualifier,
+                    media_type,
+                    expressions,
+                });
+            }
+            expressions.push(Expression::parse(context, input)?)
+        }
+    }
+}
+
+/// Parse a media query list from CSS.
+///
+/// Always returns a media query list. If any invalid media query is found, the
+/// media query list is only filled with the equivalent of "not all", see:
+///
+/// <https://drafts.csswg.org/mediaqueries/#error-handling>
+pub fn parse_media_query_list<R>(
+    context: &ParserContext,
+    input: &mut Parser,
+    error_reporter: &R,
+) -> MediaList
+where
+    R: ParseErrorReporter,
+{
+    if input.is_exhausted() {
+        return MediaList::empty();
+    }
+
+    let mut media_queries = vec![];
+    loop {
+        let start_position = input.position();
+        match input.parse_until_before(Delimiter::Comma, |i| MediaQuery::parse(context, i)) {
+            Ok(mq) => {
+                media_queries.push(mq);
+            },
+            Err(err) => {
+                media_queries.push(MediaQuery::never_matching());
+                let location = err.location;
+                let error =
+                    ContextualParseError::InvalidMediaRule(input.slice_from(start_position), err);
+                let error_context = ParserErrorContext { error_reporter };
+                context.log_css_error(&error_context, location, error);
+            },
+        }
+
+        match input.next() {
+            Ok(&Token::Comma) => {},
+            Ok(_) => unreachable!(),
+            Err(_) => break,
+        }
+    }
+
+    MediaList {
+        media_queries: media_queries,
+    }
+}
+
+impl MediaList {
+    /// Evaluate a whole `MediaList` against `Device`.
+    pub fn evaluate(&self, device: &Device, quirks_mode: QuirksMode) -> bool {
+        // Check if it is an empty media query list or any queries match (OR condition)
+        // https://drafts.csswg.org/mediaqueries-4/#mq-list
+        self.media_queries.is_empty() || self.media_queries.iter().any(|mq| {
+            let media_match = mq.media_type.matches(device.media_type());
+
+            // Check if all conditions match (AND condition)
+            let query_match = media_match &&
+                mq.expressions
+                    .iter()
+                    .all(|expression| expression.matches(&device, quirks_mode));
+
+            // Apply the logical NOT qualifier to the result
+            match mq.qualifier {
+                Some(Qualifier::Not) => !query_match,
+                _ => query_match,
+            }
+        })
+    }
+
+    /// Whether this `MediaList` contains no media queries.
+    pub fn is_empty(&self) -> bool {
+        self.media_queries.is_empty()
+    }
+
+    /// Append a new media query item to the media list.
+    /// <https://drafts.csswg.org/cssom/#dom-medialist-appendmedium>
+    ///
+    /// Returns true if added, false if fail to parse the medium string.
+    pub fn append_medium(&mut self, context: &ParserContext, new_medium: &str) -> bool {
+        let mut input = ParserInput::new(new_medium);
+        let mut parser = Parser::new(&mut input);
+        let new_query = match MediaQuery::parse(&context, &mut parser) {
+            Ok(query) => query,
+            Err(_) => {
+                return false;
+            },
+        };
+        // This algorithm doesn't actually matches the current spec,
+        // but it matches the behavior of Gecko and Edge.
+        // See https://github.com/w3c/csswg-drafts/issues/697
+        self.media_queries.retain(|query| query != &new_query);
+        self.media_queries.push(new_query);
+        true
+    }
+
+    /// Delete a media query from the media list.
+    /// <https://drafts.csswg.org/cssom/#dom-medialist-deletemedium>
+    ///
+    /// Returns true if found and deleted, false otherwise.
+    pub fn delete_medium(&mut self, context: &ParserContext, old_medium: &str) -> bool {
+        let mut input = ParserInput::new(old_medium);
+        let mut parser = Parser::new(&mut input);
+        let old_query = match MediaQuery::parse(context, &mut parser) {
+            Ok(query) => query,
+            Err(_) => {
+                return false;
+            },
+        };
+        let old_len = self.media_queries.len();
+        self.media_queries.retain(|query| query != &old_query);
+        old_len != self.media_queries.len()
+    }
+}