style: Rename Expression to MediaFeatureExpression.

Which is more appropriate, given it represents a `<media-feature>` per spec, and
expression is a bit overloaded :)

Bug: 1422225
Reviewed-by: xidorn
MozReview-Commit-ID: Fed1nJhHxDu

components/style/gecko/media_queries.rs

@@ -292,16 +292,16 @@ enum RangeOrOperator {
     Operator(Operator),
 }
 
-/// A expression for gecko contains a reference to the media feature, the value
+/// A range expression for gecko contains a reference to the media feature, the
-/// the media query contained, and the range to evaluate.
+/// value the media query contained, and the range to evaluate.
 #[derive(Clone, Debug, MallocSizeOf)]
-pub struct Expression {
+pub struct MediaFeatureExpression {
     feature: &'static nsMediaFeature,
     value: Option<MediaExpressionValue>,
     range_or_operator: Option<RangeOrOperator>,
 }
 
-impl ToCss for Expression {
+impl ToCss for MediaFeatureExpression {
     fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
     where
         W: fmt::Write,
@@ -341,8 +341,8 @@ impl ToCss for Expression {
     }
 }
 
-impl PartialEq for Expression {
+impl PartialEq for MediaFeatureExpression {
-    fn eq(&self, other: &Expression) -> bool {
+    fn eq(&self, other: &Self) -> bool {
         self.feature.mName == other.feature.mName && self.value == other.value &&
             self.range_or_operator == other.range_or_operator
     }
@@ -379,7 +379,10 @@ pub enum MediaExpressionValue {
 }
 
 impl MediaExpressionValue {
-    fn from_css_value(for_expr: &Expression, css_value: &nsCSSValue) -> Option<Self> {
+    fn from_css_value(
+        for_expr: &MediaFeatureExpression,
+        css_value: &nsCSSValue,
+    ) -> Option<Self> {
         // NB: If there's a null value, that means that we don't support the
         // feature.
         if css_value.mUnit == nsCSSUnit::eCSSUnit_Null {
@@ -437,7 +440,7 @@ impl MediaExpressionValue {
 }
 
 impl MediaExpressionValue {
-    fn to_css<W>(&self, dest: &mut CssWriter<W>, for_expr: &Expression) -> fmt::Result
+    fn to_css<W>(&self, dest: &mut CssWriter<W>, for_expr: &MediaFeatureExpression) -> fmt::Result
     where
         W: fmt::Write,
     {
@@ -615,7 +618,7 @@ fn consume_operation_or_colon(
     }))
 }
 
-impl Expression {
+impl MediaFeatureExpression {
     /// Trivially construct a new expression.
     fn new(
         feature: &'static nsMediaFeature,
@@ -746,11 +749,7 @@ impl Expression {
                         ));
                     }
 
-                    return Ok(Expression::new(
+                    return Ok(Self::new(feature, None, None));
-                        feature,
-                        None,
-                        None,
-                    ));
                 }
                 Ok(operator) => operator,
             };
@@ -785,7 +784,7 @@ impl Expression {
                         .new_custom_error(StyleParseErrorKind::MediaQueryExpectedFeatureValue)
                 })?;
 
-            Ok(Expression::new(feature, Some(value), range_or_operator))
+            Ok(Self::new(feature, Some(value), range_or_operator))
         })
     }
 

components/style/media_queries/media_query.rs

@@ -13,7 +13,7 @@ use selectors::parser::SelectorParseErrorKind;
 use std::fmt::{self, Write};
 use str::string_as_ascii_lowercase;
 use style_traits::{CssWriter, ParseError, StyleParseErrorKind, ToCss};
-use super::Expression;
+use super::MediaFeatureExpression;
 use values::CustomIdent;
 
 /// <https://drafts.csswg.org/mediaqueries/#mq-prefix>
@@ -65,8 +65,8 @@ pub struct MediaQuery {
     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.
+    /// The set of range expressions that this media query contains.
-    pub expressions: Vec<Expression>,
+    pub expressions: Vec<MediaFeatureExpression>,
 }
 
 impl ToCss for MediaQuery {
@@ -143,7 +143,7 @@ impl MediaQuery {
                 }
 
                 // Without a media type, require at least one expression.
-                expressions.push(Expression::parse(context, input)?);
+                expressions.push(MediaFeatureExpression::parse(context, input)?);
 
                 MediaQueryType::All
             },
@@ -161,7 +161,7 @@ impl MediaQuery {
                     expressions,
                 });
             }
-            expressions.push(Expression::parse(context, input)?)
+            expressions.push(MediaFeatureExpression::parse(context, input)?)
         }
     }
 }

components/style/media_queries/mod.rs

@@ -13,6 +13,6 @@ pub use self::media_list::MediaList;
 pub use self::media_query::{MediaQuery, MediaQueryType, MediaType, Qualifier};
 
 #[cfg(feature = "servo")]
-pub use servo::media_queries::{Device, Expression};
+pub use servo::media_queries::{Device, MediaFeatureExpression};
 #[cfg(feature = "gecko")]
-pub use gecko::media_queries::{Device, Expression};
+pub use gecko::media_queries::{Device, MediaFeatureExpression};

components/style/servo/media_queries.rs

@@ -170,9 +170,9 @@ pub enum ExpressionKind {
 /// <http://dev.w3.org/csswg/mediaqueries-3/#media1>
 #[derive(Clone, Debug, PartialEq)]
 #[cfg_attr(feature = "servo", derive(MallocSizeOf))]
-pub struct Expression(pub ExpressionKind);
+pub struct MediaFeatureExpression(pub ExpressionKind);
 
-impl Expression {
+impl MediaFeatureExpression {
     /// The kind of expression we're, just for unit testing.
     ///
     /// Eventually this will become servo-only.
@@ -196,7 +196,7 @@ impl Expression {
             let name = input.expect_ident_cloned()?;
             input.expect_colon()?;
             // TODO: Handle other media features
-            Ok(Expression(match_ignore_ascii_case! { &name,
+            Ok(MediaFeatureExpression(match_ignore_ascii_case! { &name,
                 "min-width" => {
                     ExpressionKind::Width(Range::Min(specified::Length::parse_non_negative(context, input)?))
                 },
@@ -206,7 +206,7 @@ impl Expression {
                 "width" => {
                     ExpressionKind::Width(Range::Eq(specified::Length::parse_non_negative(context, input)?))
                 },
-                _ => return Err(input.new_custom_error(SelectorParseErrorKind::UnexpectedIdent(name.clone())))
+                _ => return Err(input.new_custom_error(SelectorParseErrorKind::UnexpectedIdent(name)))
             }))
         })
     }
@@ -228,7 +228,7 @@ impl Expression {
     }
 }
 
-impl ToCss for Expression {
+impl ToCss for MediaFeatureExpression {
     fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
     where
         W: Write,
@@ -246,8 +246,8 @@ impl ToCss for Expression {
 
 /// An enumeration that represents a ranged value.
 ///
-/// Only public for testing, implementation details of `Expression` may change
+/// Only public for testing, implementation details of `MediaFeatureExpression`
-/// for Stylo.
+/// may change for Stylo.
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
 #[cfg_attr(feature = "servo", derive(MallocSizeOf))]
 pub enum Range<T> {

components/style/values/specified/source_size_list.rs

@@ -8,7 +8,7 @@ use app_units::Au;
 use cssparser::{Delimiter, Parser, Token};
 #[cfg(feature = "gecko")]
 use gecko_bindings::sugar::ownership::{HasBoxFFI, HasFFI, HasSimpleFFI};
-use media_queries::{Device, Expression as MediaExpression};
+use media_queries::{Device, MediaFeatureExpression};
 use parser::{Parse, ParserContext};
 use selectors::context::QuirksMode;
 use style_traits::ParseError;
@@ -21,7 +21,7 @@ use values::specified::{Length, NoCalcLength, ViewportPercentageLength};
 pub struct SourceSize {
     // FIXME(emilio): This should be a `MediaCondition`, and support `and` and
     // `or`.
-    condition: MediaExpression,
+    condition: MediaFeatureExpression,
     value: Length,
 }
 
@@ -30,7 +30,7 @@ impl Parse for SourceSize {
         context: &ParserContext,
         input: &mut Parser<'i, 't>,
     ) -> Result<Self, ParseError<'i>> {
-        let condition = MediaExpression::parse(context, input)?;
+        let condition = MediaFeatureExpression::parse(context, input)?;
         let value = Length::parse_non_negative(context, input)?;
 
         Ok(Self { condition, value })