First bits of shadow dom layout

5 files changed, 118 insertions, 30 deletions

diff --git a/components/layout_thread/dom_wrapper.rs b/components/layout_thread/dom_wrapper.rs
index 497c7f135d2..6227df9f04c 100644
--- a/components/layout_thread/dom_wrapper.rs
+++ b/components/layout_thread/dom_wrapper.rs
@@ -40,13 +40,16 @@ use net_traits::image::base::{Image, ImageMetadata};
 use range::Range;
 use script::layout_exports::NodeFlags;
 use script::layout_exports::PendingRestyle;
+use script::layout_exports::ShadowRoot;
 use script::layout_exports::{
-    CharacterDataTypeId, ElementTypeId, HTMLElementTypeId, NodeTypeId, TextTypeId,
+    CharacterDataTypeId, DocumentFragmentTypeId, ElementTypeId, HTMLElementTypeId, NodeTypeId,
+    TextTypeId,
 };
 use script::layout_exports::{Document, Element, Node, Text};
 use script::layout_exports::{LayoutCharacterDataHelpers, LayoutDocumentHelpers};
 use script::layout_exports::{
-    LayoutDom, LayoutElementHelpers, LayoutNodeHelpers, RawLayoutElementHelpers,
+    LayoutDom, LayoutElementHelpers, LayoutNodeHelpers, LayoutShadowRootHelpers,
+    RawLayoutElementHelpers,
 };
 use script_layout_interface::wrapper_traits::{
     DangerousThreadSafeLayoutNode, GetLayoutData, LayoutNode,
@@ -160,35 +163,60 @@ impl<'ln> NodeInfo for ServoLayoutNode<'ln> {
     }
 }
 
-#[derive(Clone, Copy, PartialEq)]
-enum Impossible {}
+#[derive(Clone, Copy)]
+pub struct ServoShadowRoot<'a> {
+    /// The wrapped shadow root.
+    shadow_root: LayoutDom<ShadowRoot>,
 
-#[derive(Clone, Copy, PartialEq)]
-pub struct ShadowRoot<'lr>(Impossible, PhantomData<&'lr ()>);
+    /// Being chained to a PhantomData prevents `ShadowRoot`s from escaping.
+    chain: PhantomData<&'a ()>,
+}
 
-impl<'lr> TShadowRoot for ShadowRoot<'lr> {
-    type ConcreteNode = ServoLayoutNode<'lr>;
+impl<'sr> Debug for ServoShadowRoot<'sr> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        self.as_node().fmt(f)
+    }
+}
+
+impl<'a> PartialEq for ServoShadowRoot<'a> {
+    #[inline]
+    fn eq(&self, other: &ServoShadowRoot) -> bool {
+        self.shadow_root == other.shadow_root
+    }
+}
+
+impl<'sr> TShadowRoot for ServoShadowRoot<'sr> {
+    type ConcreteNode = ServoLayoutNode<'sr>;
 
     fn as_node(&self) -> Self::ConcreteNode {
-        match self.0 {}
+        ServoLayoutNode::from_layout_js(self.shadow_root.upcast())
     }
 
-    fn host(&self) -> ServoLayoutElement<'lr> {
-        match self.0 {}
+    fn host(&self) -> ServoLayoutElement<'sr> {
+        ServoLayoutElement::from_layout_js(unsafe { self.shadow_root.get_host_for_layout() })
     }
 
     fn style_data<'a>(&self) -> Option<&'a CascadeData>
     where
         Self: 'a,
     {
-        match self.0 {}
+        None
+    }
+}
+
+impl<'sr> ServoShadowRoot<'sr> {
+    fn from_layout_js(shadow_root: LayoutDom<ShadowRoot>) -> ServoShadowRoot<'sr> {
+        ServoShadowRoot {
+            shadow_root,
+            chain: PhantomData,
+        }
     }
 }
 
 impl<'ln> TNode for ServoLayoutNode<'ln> {
     type ConcreteDocument = ServoLayoutDocument<'ln>;
     type ConcreteElement = ServoLayoutElement<'ln>;
-    type ConcreteShadowRoot = ShadowRoot<'ln>;
+    type ConcreteShadowRoot = ServoShadowRoot<'ln>;
 
     fn parent_node(&self) -> Option<Self> {
         unsafe {
@@ -256,8 +284,8 @@ impl<'ln> TNode for ServoLayoutNode<'ln> {
             .map(ServoLayoutDocument::from_layout_js)
     }
 
-    fn as_shadow_root(&self) -> Option<ShadowRoot<'ln>> {
-        None
+    fn as_shadow_root(&self) -> Option<ServoShadowRoot<'ln>> {
+        self.node.downcast().map(ServoShadowRoot::from_layout_js)
     }
 
     fn is_connected(&self) -> bool {
@@ -616,12 +644,23 @@ impl<'le> TElement for ServoLayoutElement<'le> {
         }
     }
 
-    fn shadow_root(&self) -> Option<ShadowRoot<'le>> {
-        None
+    /// The shadow root this element is a host of.
+    fn shadow_root(&self) -> Option<ServoShadowRoot<'le>> {
+        unsafe {
+            self.element
+                .get_shadow_root_for_layout()
+                .map(ServoShadowRoot::from_layout_js)
+        }
     }
 
-    fn containing_shadow(&self) -> Option<ShadowRoot<'le>> {
-        None
+    /// The shadow root which roots the subtree this element is contained in.
+    fn containing_shadow(&self) -> Option<ServoShadowRoot<'le>> {
+        unsafe {
+            self.element
+                .upcast()
+                .owner_shadow_root_for_layout()
+                .map(ServoShadowRoot::from_layout_js)
+        }
     }
 }
 
@@ -706,11 +745,20 @@ impl<'le> ::selectors::Element for ServoLayoutElement<'le> {
     }
 
     fn parent_node_is_shadow_root(&self) -> bool {
-        false
+        match self.as_node().parent_node() {
+            None => false,
+            Some(node) => {
+                node.script_type_id() ==
+                    NodeTypeId::DocumentFragment(DocumentFragmentTypeId::ShadowRoot)
+            },
+        }
     }
 
     fn containing_shadow_host(&self) -> Option<Self> {
-        None
+        match self.containing_shadow() {
+            Some(shadow) => Some(shadow.host()),
+            None => None,
+        }
     }
 
     fn prev_sibling_element(&self) -> Option<ServoLayoutElement<'le>> {
diff --git a/components/script/dom/element.rs b/components/script/dom/element.rs
index 5b5b93f78c1..f9923da3fea 100644
--- a/components/script/dom/element.rs
+++ b/components/script/dom/element.rs
@@ -15,6 +15,7 @@ use crate::dom::bindings::codegen::Bindings::EventBinding::EventMethods;
 use crate::dom::bindings::codegen::Bindings::FunctionBinding::Function;
 use crate::dom::bindings::codegen::Bindings::HTMLTemplateElementBinding::HTMLTemplateElementMethods;
 use crate::dom::bindings::codegen::Bindings::NodeBinding::{GetRootNodeOptions, NodeMethods};
+use crate::dom::bindings::codegen::Bindings::ShadowRootBinding::ShadowRootBinding::ShadowRootMethods;
 use crate::dom::bindings::codegen::Bindings::WindowBinding::WindowMethods;
 use crate::dom::bindings::codegen::Bindings::WindowBinding::{ScrollBehavior, ScrollToOptions};
 use crate::dom::bindings::codegen::UnionTypes::NodeOrString;
@@ -76,7 +77,7 @@ use crate::dom::node::{NodeDamage, NodeFlags, UnbindContext};
 use crate::dom::nodelist::NodeList;
 use crate::dom::promise::Promise;
 use crate::dom::servoparser::ServoParser;
-use crate::dom::shadowroot::ShadowRoot;
+use crate::dom::shadowroot::{LayoutShadowRootHelpers, ShadowRoot};
 use crate::dom::text::Text;
 use crate::dom::validation::Validatable;
 use crate::dom::virtualmethods::{vtable_for, VirtualMethods};
@@ -587,6 +588,9 @@ pub trait LayoutElementHelpers {
     fn get_state_for_layout(&self) -> ElementState;
     fn insert_selector_flags(&self, flags: ElementSelectorFlags);
     fn has_selector_flags(&self, flags: ElementSelectorFlags) -> bool;
+    /// The shadow root this element is a host of.
+    #[allow(unsafe_code)]
+    unsafe fn get_shadow_root_for_layout(&self) -> Option<LayoutDom<ShadowRoot>>;
 }
 
 impl LayoutElementHelpers for LayoutDom<Element> {
@@ -1049,6 +1053,12 @@ impl LayoutElementHelpers for LayoutDom<Element> {
     fn has_selector_flags(&self, flags: ElementSelectorFlags) -> bool {
         unsafe { (*self.unsafe_get()).selector_flags.get().contains(flags) }
     }
+
+    #[inline]
+    #[allow(unsafe_code)]
+    unsafe fn get_shadow_root_for_layout(&self) -> Option<LayoutDom<ShadowRoot>> {
+        (*self.unsafe_get()).shadow_root.get_inner_as_layout()
+    }
 }
 
 impl Element {
@@ -2877,11 +2887,18 @@ impl<'a> SelectorsElement for DomRoot<Element> {
     }
 
     fn parent_node_is_shadow_root(&self) -> bool {
-        false
+        match self.upcast::<Node>().GetParentNode() {
+            None => false,
+            Some(node) => node.is::<ShadowRoot>(),
+        }
     }
 
     fn containing_shadow_host(&self) -> Option<Self> {
-        None
+        if let Some(shadow_root) = self.upcast::<Node>().owner_shadow_root() {
+            Some(shadow_root.Host())
+        } else {
+            None
+        }
     }
 
     fn match_pseudo_element(
diff --git a/components/script/dom/node.rs b/components/script/dom/node.rs
index d8c1a2f4d5d..b20f8cf037e 100644
--- a/components/script/dom/node.rs
+++ b/components/script/dom/node.rs
@@ -295,8 +295,8 @@ impl Node {
             if parent_in_shadow_tree {
                 if let Some(shadow_root) = self.downcast::<ShadowRoot>() {
                     node.set_owner_shadow_root(&*shadow_root);
-                } else {
-                    node.set_owner_shadow_root(&*self.owner_shadow_root());
+                } else if let Some(shadow_root) = self.owner_shadow_root() {
+                    node.set_owner_shadow_root(&*shadow_root);
                 }
             }
             let mut is_connected = parent_is_connected;
@@ -946,8 +946,8 @@ impl Node {
         self.owner_doc.set(Some(document));
     }
 
-    pub fn owner_shadow_root(&self) -> DomRoot<ShadowRoot> {
-        self.owner_shadow_root.get().unwrap()
+    pub fn owner_shadow_root(&self) -> Option<DomRoot<ShadowRoot>> {
+        self.owner_shadow_root.get()
     }
 
     pub fn set_owner_shadow_root(&self, shadow_root: &ShadowRoot) {
@@ -1184,6 +1184,7 @@ pub trait LayoutNodeHelpers {
     unsafe fn next_sibling_ref(&self) -> Option<LayoutDom<Node>>;
 
     unsafe fn owner_doc_for_layout(&self) -> LayoutDom<Document>;
+    unsafe fn owner_shadow_root_for_layout(&self) -> Option<LayoutDom<ShadowRoot>>;
 
     unsafe fn is_element_for_layout(&self) -> bool;
     unsafe fn get_flag(&self, flag: NodeFlags) -> bool;
@@ -1262,6 +1263,12 @@ impl LayoutNodeHelpers for LayoutDom<Node> {
 
     #[inline]
     #[allow(unsafe_code)]
+    unsafe fn owner_shadow_root_for_layout(&self) -> Option<LayoutDom<ShadowRoot>> {
+        (*self.unsafe_get()).owner_shadow_root.get_inner_as_layout()
+    }
+
+    #[inline]
+    #[allow(unsafe_code)]
     unsafe fn get_flag(&self, flag: NodeFlags) -> bool {
         (*self.unsafe_get()).flags.get().contains(flag)
     }
diff --git a/components/script/dom/shadowroot.rs b/components/script/dom/shadowroot.rs
index e64401ab494..55470a9935d 100644
--- a/components/script/dom/shadowroot.rs
+++ b/components/script/dom/shadowroot.rs
@@ -7,7 +7,7 @@ use crate::dom::bindings::codegen::Bindings::ShadowRootBinding::{self, ShadowRoo
 use crate::dom::bindings::inheritance::Castable;
 use crate::dom::bindings::num::Finite;
 use crate::dom::bindings::reflector::reflect_dom_object;
-use crate::dom::bindings::root::{Dom, DomRoot, MutNullableDom};
+use crate::dom::bindings::root::{Dom, DomRoot, LayoutDom, MutNullableDom};
 use crate::dom::cssstylesheet::CSSStyleSheet;
 use crate::dom::document::Document;
 use crate::dom::documentfragment::DocumentFragment;
@@ -121,3 +121,16 @@ impl ShadowRootMethods for ShadowRoot {
         })
     }
 }
+
+#[allow(unsafe_code)]
+pub trait LayoutShadowRootHelpers {
+    unsafe fn get_host_for_layout(&self) -> LayoutDom<Element>;
+}
+
+impl LayoutShadowRootHelpers for LayoutDom<ShadowRoot> {
+    #[inline]
+    #[allow(unsafe_code)]
+    unsafe fn get_host_for_layout(&self) -> LayoutDom<Element> {
+        (*self.unsafe_get()).host.to_layout()
+    }
+}
diff --git a/components/script/lib.rs b/components/script/lib.rs
index a057540ae22..3f48e3d9118 100644
--- a/components/script/lib.rs
+++ b/components/script/lib.rs
@@ -84,7 +84,9 @@ mod webdriver_handlers;
 ///
 /// TODO(emilio): A few of the FooHelpers can go away, presumably...
 pub mod layout_exports {
-    pub use crate::dom::bindings::inheritance::{CharacterDataTypeId, ElementTypeId};
+    pub use crate::dom::bindings::inheritance::{
+        CharacterDataTypeId, DocumentFragmentTypeId, ElementTypeId,
+    };
     pub use crate::dom::bindings::inheritance::{HTMLElementTypeId, NodeTypeId, TextTypeId};
     pub use crate::dom::bindings::root::LayoutDom;
     pub use crate::dom::characterdata::LayoutCharacterDataHelpers;
@@ -92,6 +94,7 @@ pub mod layout_exports {
     pub use crate::dom::element::{Element, LayoutElementHelpers, RawLayoutElementHelpers};
     pub use crate::dom::node::NodeFlags;
     pub use crate::dom::node::{LayoutNodeHelpers, Node};
+    pub use crate::dom::shadowroot::{LayoutShadowRootHelpers, ShadowRoot};
     pub use crate::dom::text::Text;
 }