Implement MediaList for Stylo.

components/style/gecko/media_queries.rs

@@ -137,8 +137,15 @@ impl ToCss for Expression {
     }
 }
 
+impl PartialEq for Expression {
+    fn eq(&self, other: &Expression) -> bool {
+        self.feature.mName == other.feature.mName &&
+            self.value == other.value && self.range == other.range
+    }
+}
+
 /// A resolution.
-#[derive(Debug, Clone)]
+#[derive(PartialEq, Debug, Clone)]
 pub enum Resolution {
     /// Dots per inch.
     Dpi(CSSFloat),
@@ -200,7 +207,7 @@ unsafe fn string_from_ns_string_buffer(buffer: *const nsStringBuffer) -> String
 }
 
 /// A value found or expected in a media expression.
-#[derive(Debug, Clone)]
+#[derive(PartialEq, Debug, Clone)]
 pub enum MediaExpressionValue {
     /// A length.
     Length(specified::Length),

components/style/gecko_bindings/bindings.rs

@@ -1627,6 +1627,34 @@ extern "C" {
     pub fn Servo_DeclarationBlock_SetTextDecorationColorOverride(declarations:
                                                                      RawServoDeclarationBlockBorrowed);
 }
+extern "C" {
+    pub fn Servo_MediaList_GetText(list: RawServoMediaListBorrowed,
+                                   result: *mut nsAString_internal);
+}
+extern "C" {
+    pub fn Servo_MediaList_SetText(list: RawServoMediaListBorrowed,
+                                   text: *const nsACString_internal);
+}
+extern "C" {
+    pub fn Servo_MediaList_GetLength(list: RawServoMediaListBorrowed) -> u32;
+}
+extern "C" {
+    pub fn Servo_MediaList_GetMediumAt(list: RawServoMediaListBorrowed,
+                                       index: u32,
+                                       result: *mut nsAString_internal)
+     -> bool;
+}
+extern "C" {
+    pub fn Servo_MediaList_AppendMedium(list: RawServoMediaListBorrowed,
+                                        new_medium:
+                                            *const nsACString_internal);
+}
+extern "C" {
+    pub fn Servo_MediaList_DeleteMedium(list: RawServoMediaListBorrowed,
+                                        old_medium:
+                                            *const nsACString_internal)
+     -> bool;
+}
 extern "C" {
     pub fn Servo_CSSSupports2(name: *const nsACString_internal,
                               value: *const nsACString_internal) -> bool;

components/style/media_queries.rs

@@ -66,7 +66,7 @@ impl ToCss for Qualifier {
 /// A [media query][mq].
 ///
 /// [mq]: https://drafts.csswg.org/mediaqueries/
-#[derive(Clone, Debug)]
+#[derive(PartialEq, Clone, Debug)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub struct MediaQuery {
     /// The qualifier for this query.
@@ -299,4 +299,37 @@ impl MediaList {
     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, new_medium: &str) -> bool {
+        let mut parser = Parser::new(new_medium);
+        let new_query = match MediaQuery::parse(&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, old_medium: &str) -> bool {
+        let mut parser = Parser::new(old_medium);
+        let old_query = match MediaQuery::parse(&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()
+    }
 }