Add style adjustments for ruby.

components/style/properties/computed_value_flags.rs

@@ -18,5 +18,15 @@ bitflags! {
         /// text-decoration-line is a reset property, but gets propagated in the
         /// frame/box tree.
         const HAS_TEXT_DECORATION_LINES = 1 << 0,
+
+        /// Whether line break inside should be suppressed.
+        ///
+        /// If this flag is set, the line should not be broken inside,
+        /// which means inlines act as if nowrap is set, <br> element is
+        /// suppressed, and blocks are inlinized.
+        ///
+        /// This bit is propagated to all children of line participants.
+        /// It is currently used by ruby to make its content unbreakable.
+        const SHOULD_SUPPRESS_LINEBREAK = 1 << 1,
     }
 }

components/style/properties/longhand/box.mako.rs

@@ -53,6 +53,34 @@
                 )
             }
 
+            /// Returns whether an element with this display type is a line
+            /// participant, which means it may lay its children on the same
+            /// line as itself.
+            pub fn is_line_participant(&self) -> bool {
+                matches!(*self,
+                         T::inline
+                         % if product == "gecko":
+                         | T::contents
+                         | T::ruby
+                         | T::ruby_base_container
+                         % endif
+                )
+            }
+
+            /// Returns whether this "display" value is one of the types for
+            /// ruby.
+            #[cfg(feature = "gecko")]
+            pub fn is_ruby_type(&self) -> bool {
+                matches!(*self, T::ruby | T::ruby_base | T::ruby_text |
+                         T::ruby_base_container | T::ruby_text_container)
+            }
+
+            /// Returns whether this "display" value is a ruby level container.
+            #[cfg(feature = "gecko")]
+            pub fn is_ruby_level_container(&self) -> bool {
+                matches!(*self, T::ruby_base_container | T::ruby_text_container)
+            }
+
             /// Convert this display into an equivalent block display.
             ///
             /// Also used for style adjustments.
@@ -82,6 +110,25 @@
                     // Everything else becomes block.
                     _ => T::block,
                 }
+
+            }
+
+            /// Convert this display into an inline-outside display.
+            ///
+            /// Ideally it should implement spec: https://drafts.csswg.org/css-display/#inlinify
+            /// but the spec isn't stable enough, so we copy what Gecko does for now.
+            #[cfg(feature = "gecko")]
+            pub fn inlinify(&self) -> Self {
+                match *self {
+                    T::block | T::flow_root => T::inline_block,
+                    T::table => T::inline_table,
+                    T::flex => T::inline_flex,
+                    T::grid => T::inline_grid,
+                    T::_moz_box => T::_moz_inline_box,
+                    T::_moz_stack => T::_moz_inline_stack,
+                    T::_webkit_box => T::_webkit_inline_box,
+                    other => other,
+                }
             }
         }
     }

components/style/properties/longhand/text.mako.rs

@@ -135,6 +135,7 @@
 ${helpers.single_keyword("unicode-bidi",
                          "normal embed isolate bidi-override isolate-override plaintext",
                          animation_value_type="discrete",
+                         need_clone="True",
                          spec="https://drafts.csswg.org/css-writing-modes/#propdef-unicode-bidi")}
 
 <%helpers:longhand name="text-decoration-line"

components/style/properties/properties.mako.rs

@@ -2486,6 +2486,12 @@ impl<'a> StyleBuilder<'a> {
                                                          -> Option<<&mut style_structs::${style_struct.name}> {
             self.${style_struct.ident}.get_if_mutated()
         }
+
+        /// Reset the current `${style_struct.name}` style to its default value.
+        pub fn reset_${style_struct.name_lower}(&mut self, default: &'a ComputedValues) {
+            self.${style_struct.ident} =
+                StyleStructRef::Borrowed(default.${style_struct.name_lower}_arc());
+        }
     % endfor
 
     /// Returns whether this computed style represents a floated object.
@@ -2597,8 +2603,8 @@ bitflags! {
         /// present, non-inherited styles are reset to their initial values.
         const INHERIT_ALL = 0x01,
 
-        /// Whether to skip any root element and flex/grid item display style
-        /// fixup.
+        /// Whether to skip any display style fixup for root element, flex/grid
+        /// item, and ruby descendants.
         const SKIP_ROOT_AND_ITEM_BASED_DISPLAY_FIXUP = 0x02,
 
         /// Whether to only cascade properties that are visited dependent.
@@ -2985,7 +2991,8 @@ pub fn apply_declarations<'a, F, I>(device: &Device,
 
     {
         StyleAdjuster::new(&mut style)
-            .adjust(context.layout_parent_style, flags);
+            .adjust(context.layout_parent_style,
+                    context.device.default_computed_values(), flags);
     }
 
     % if product == "gecko":