Hoist exported ThreadSafeLayoutFoo functionality into traits.

components/layout/construct.rs

@@ -57,7 +57,7 @@ use traversal::PostorderNodeMutTraversal;
 use url::Url;
 use util::linked_list;
 use util::opts;
-use wrapper::{PseudoElementType, TextContent, ThreadSafeLayoutNode};
+use wrapper::{PseudoElementType, TextContent, ThreadSafeLayoutNode, TThreadSafeLayoutElement, TThreadSafeLayoutNode};
 
 /// The results of flow construction for a DOM node.
 #[derive(Clone)]

components/layout/flow.rs

@@ -58,7 +58,7 @@ use table_rowgroup::TableRowGroupFlow;
 use table_wrapper::TableWrapperFlow;
 use util::geometry::ZERO_RECT;
 use util::logical_geometry::{LogicalRect, LogicalSize, WritingMode};
-use wrapper::{PseudoElementType, ThreadSafeLayoutNode};
+use wrapper::{PseudoElementType, ThreadSafeLayoutNode, TThreadSafeLayoutNode};
 
 /// Virtual methods that make up a float context.
 ///

components/layout/fragment.rs

@@ -50,7 +50,7 @@ use util::geometry::ZERO_POINT;
 use util::logical_geometry::{LogicalMargin, LogicalRect, LogicalSize, WritingMode};
 use util::range::*;
 use util::str::slice_chars;
-use wrapper::{PseudoElementType, ThreadSafeLayoutNode};
+use wrapper::{PseudoElementType, ThreadSafeLayoutNode, TThreadSafeLayoutElement, TThreadSafeLayoutNode};
 
 /// Fragments (`struct Fragment`) are the leaves of the layout tree. They cannot position
 /// themselves. In general, fragments do not have a simple correspondence with CSS fragments in the

components/layout/layout_task.rs

@@ -73,7 +73,7 @@ use util::opts;
 use util::task;
 use util::task_state;
 use util::workqueue::WorkQueue;
-use wrapper::{LayoutDocument, LayoutElement, LayoutNode, ServoLayoutNode};
+use wrapper::{LayoutDocument, LayoutElement, LayoutNode, ServoLayoutNode, TThreadSafeLayoutNode};
 
 /// The number of screens of data we're allowed to generate display lists for in each direction.
 pub const DISPLAY_PORT_SIZE_FACTOR: i32 = 8;

components/layout/query.rs

@@ -31,7 +31,7 @@ use style::values::AuExtensionMethods;
 use util::cursor::Cursor;
 use util::geometry::ZERO_POINT;
 use util::logical_geometry::WritingMode;
-use wrapper::{LayoutNode, ServoLayoutNode, ThreadSafeLayoutNode};
+use wrapper::{LayoutNode, ServoLayoutNode, ThreadSafeLayoutNode, TThreadSafeLayoutNode};
 
 pub struct LayoutRPCImpl(pub Arc<Mutex<LayoutTaskData>>);
 

components/layout/table_cell.rs

@@ -24,7 +24,7 @@ use style::properties::ComputedValues;
 use table::InternalTable;
 use table_row::{CollapsedBorder, CollapsedBorderProvenance};
 use util::logical_geometry::{LogicalMargin, LogicalRect, LogicalSize, WritingMode};
-use wrapper::ThreadSafeLayoutNode;
+use wrapper::{ThreadSafeLayoutNode, TThreadSafeLayoutNode};
 
 /// A table formatting context.
 #[derive(RustcEncodable)]

components/layout/traversal.rs

@@ -18,7 +18,7 @@ use std::mem;
 use util::opts;
 use util::tid::tid;
 use wrapper::{LayoutNode, ServoLayoutNode, layout_node_to_unsafe_layout_node};
-use wrapper::{ThreadSafeLayoutNode, UnsafeLayoutNode};
+use wrapper::{ThreadSafeLayoutNode, TThreadSafeLayoutNode, UnsafeLayoutNode};
 
 /// Every time we do another layout, the old bloom filters are invalid. This is
 /// detected by ticking a generation number every layout.

components/layout/wrapper.rs

@@ -792,6 +792,163 @@ impl<T> PseudoElementType<T> {
 
 /// A thread-safe version of `LayoutNode`, used during flow construction. This type of layout
 /// node does not allow any parents or siblings of nodes to be accessed, to avoid races.
+
+pub trait TThreadSafeLayoutNode<'ln> : Clone + Copy + Sized {
+    type ConcreteThreadSafeLayoutElement: TThreadSafeLayoutElement<'ln>;
+
+    /// Converts self into an `OpaqueNode`.
+    fn opaque(&self) -> OpaqueNode;
+
+    /// Returns the type ID of this node.
+    /// Returns `None` if this is a pseudo-element; otherwise, returns `Some`.
+    fn type_id(&self) -> Option<NodeTypeId>;
+
+    fn debug_id(self) -> usize;
+
+    fn flow_debug_id(self) -> usize;
+
+    /// Returns an iterator over this node's children.
+    fn children(&self) -> ThreadSafeLayoutNodeChildrenIterator<'ln, Self>;
+
+    /// If this is an element, accesses the element data. Fails if this is not an element node.
+    #[inline]
+    fn as_element(&self) -> Self::ConcreteThreadSafeLayoutElement;
+
+    #[inline]
+    fn get_pseudo_element_type(&self) -> PseudoElementType<display::T>;
+
+    #[inline]
+    fn get_before_pseudo(&self) -> Option<Self>;
+
+    #[inline]
+    fn get_after_pseudo(&self) -> Option<Self>;
+
+    /// Borrows the layout data immutably. Fails on a conflicting borrow.
+    ///
+    /// TODO(pcwalton): Make this private. It will let us avoid borrow flag checks in some cases.
+    #[inline(always)]
+    fn borrow_layout_data(&self) -> Ref<Option<LayoutDataWrapper>>;
+
+    /// Borrows the layout data mutably. Fails on a conflicting borrow.
+    ///
+    /// TODO(pcwalton): Make this private. It will let us avoid borrow flag checks in some cases.
+    #[inline(always)]
+    fn mutate_layout_data(&self) -> RefMut<Option<LayoutDataWrapper>>;
+
+    /// Returns the style results for the given node. If CSS selector matching
+    /// has not yet been performed, fails.
+    #[inline]
+    fn style(&self) -> Ref<Arc<ComputedValues>> {
+        Ref::map(self.borrow_layout_data(), |layout_data_ref| {
+            let layout_data = layout_data_ref.as_ref().expect("no layout data");
+            let style = match self.get_pseudo_element_type() {
+                PseudoElementType::Before(_) => &layout_data.data.before_style,
+                PseudoElementType::After(_) => &layout_data.data.after_style,
+                PseudoElementType::Normal => &layout_data.shared_data.style,
+            };
+            style.as_ref().unwrap()
+        })
+    }
+
+    /// Removes the style from this node.
+    fn unstyle(self) {
+        let mut layout_data_ref = self.mutate_layout_data();
+        let layout_data = layout_data_ref.as_mut().expect("no layout data");
+
+        let style =
+            match self.get_pseudo_element_type() {
+                PseudoElementType::Before(_) => &mut layout_data.data.before_style,
+                PseudoElementType::After (_) => &mut layout_data.data.after_style,
+                PseudoElementType::Normal    => &mut layout_data.shared_data.style,
+            };
+
+        *style = None;
+    }
+
+    fn is_ignorable_whitespace(&self) -> bool;
+
+    /// Get the description of how to account for recent style changes.
+    /// This is a simple bitfield and fine to copy by value.
+    fn restyle_damage(self) -> RestyleDamage {
+        let layout_data_ref = self.borrow_layout_data();
+        layout_data_ref.as_ref().unwrap().data.restyle_damage
+    }
+
+    /// Set the restyle damage field.
+    fn set_restyle_damage(self, damage: RestyleDamage) {
+        let mut layout_data_ref = self.mutate_layout_data();
+        match *layout_data_ref {
+            Some(ref mut layout_data) => layout_data.data.restyle_damage = damage,
+            _ => panic!("no layout data for this node"),
+        }
+    }
+
+    /// Returns the layout data flags for this node.
+    fn flags(self) -> LayoutDataFlags;
+
+    /// Adds the given flags to this node.
+    fn insert_flags(self, new_flags: LayoutDataFlags) {
+        let mut layout_data_ref = self.mutate_layout_data();
+        match *layout_data_ref {
+            Some(ref mut layout_data) => layout_data.data.flags.insert(new_flags),
+            _ => panic!("no layout data for this node"),
+        }
+    }
+
+    /// Removes the given flags from this node.
+    fn remove_flags(self, flags: LayoutDataFlags) {
+        let mut layout_data_ref = self.mutate_layout_data();
+        match *layout_data_ref {
+            Some(ref mut layout_data) => layout_data.data.flags.remove(flags),
+            _ => panic!("no layout data for this node"),
+        }
+    }
+
+    /// Returns true if this node contributes content. This is used in the implementation of
+    /// `empty_cells` per CSS 2.1 § 17.6.1.1.
+    fn is_content(&self) -> bool {
+        match self.type_id() {
+            Some(NodeTypeId::Element(..)) | Some(NodeTypeId::CharacterData(CharacterDataTypeId::Text(..))) => true,
+            _ => false
+        }
+    }
+
+    /// If this is a text node, generated content, or a form element, copies out
+    /// its content. Otherwise, panics.
+    ///
+    /// FIXME(pcwalton): This might have too much copying and/or allocation. Profile this.
+    fn text_content(&self) -> TextContent;
+
+    /// If the insertion point is within this node, returns it. Otherwise, returns `None`.
+    fn insertion_point(&self) -> Option<CharIndex>;
+
+    /// If this is an image element, returns its URL. If this is not an image element, fails.
+    ///
+    /// FIXME(pcwalton): Don't copy URLs.
+    fn image_url(&self) -> Option<Url>;
+
+    fn canvas_data(&self) -> Option<HTMLCanvasData>;
+
+    /// If this node is an iframe element, returns its pipeline ID. If this node is
+    /// not an iframe element, fails.
+    fn iframe_pipeline_id(&self) -> PipelineId;
+
+    fn get_colspan(&self) -> u32;
+}
+
+// These can violate the thread-safety and therefore are not public.
+trait DangerousThreadSafeLayoutNode<'ln> : TThreadSafeLayoutNode<'ln> {
+    unsafe fn dangerous_first_child(&self) -> Option<Self>;
+    unsafe fn dangerous_next_sibling(&self) -> Option<Self>;
+}
+
+pub trait TThreadSafeLayoutElement<'le> {
+    type ConcreteThreadSafeLayoutNode: TThreadSafeLayoutNode<'le>;
+
+    #[inline]
+    fn get_attr(&self, namespace: &Namespace, name: &Atom) -> Option<&'le str>;
+}
+
 #[derive(Copy, Clone)]
 pub struct ThreadSafeLayoutNode<'ln> {
     /// The wrapped node.
@@ -800,6 +957,17 @@ pub struct ThreadSafeLayoutNode<'ln> {
     pseudo: PseudoElementType<display::T>,
 }
 
+impl<'ln> DangerousThreadSafeLayoutNode<'ln> for ThreadSafeLayoutNode<'ln> {
+    unsafe fn dangerous_first_child(&self) -> Option<Self> {
+            self.get_jsmanaged().first_child_ref()
+                .map(|node| self.new_with_this_lifetime(&node))
+    }
+    unsafe fn dangerous_next_sibling(&self) -> Option<Self> {
+            self.get_jsmanaged().next_sibling_ref()
+                .map(|node| self.new_with_this_lifetime(&node))
+    }
+}
+
 impl<'ln> ThreadSafeLayoutNode<'ln> {
     /// Creates a new layout node with the same lifetime as this layout node.
     pub unsafe fn new_with_this_lifetime(&self, node: &LayoutJS<Node>) -> ThreadSafeLayoutNode<'ln> {
@@ -832,14 +1000,23 @@ impl<'ln> ThreadSafeLayoutNode<'ln> {
         self.node.get_jsmanaged()
     }
 
-    /// Converts self into an `OpaqueNode`.
-    pub fn opaque(&self) -> OpaqueNode {
+    /// Borrows the layout data without checking.
+    #[inline(always)]
+    fn borrow_layout_data_unchecked(&self) -> *const Option<LayoutDataWrapper> {
+        unsafe {
+            self.node.borrow_layout_data_unchecked()
+        }
+    }
+}
+
+impl<'ln> TThreadSafeLayoutNode<'ln> for ThreadSafeLayoutNode<'ln> {
+    type ConcreteThreadSafeLayoutElement = ThreadSafeLayoutElement<'ln>;
+
+    fn opaque(&self) -> OpaqueNode {
         OpaqueNodeMethods::from_jsmanaged(unsafe { self.get_jsmanaged() })
     }
 
-    /// Returns the type ID of this node.
-    /// Returns `None` if this is a pseudo-element; otherwise, returns `Some`.
-    pub fn type_id(&self) -> Option<NodeTypeId> {
+    fn type_id(&self) -> Option<NodeTypeId> {
         if self.pseudo != PseudoElementType::Normal {
             return None
         }
@@ -847,22 +1024,19 @@ impl<'ln> ThreadSafeLayoutNode<'ln> {
         Some(self.node.type_id())
     }
 
-    pub fn debug_id(self) -> usize {
+    fn debug_id(self) -> usize {
         self.node.debug_id()
     }
 
-    pub fn flow_debug_id(self) -> usize {
+    fn flow_debug_id(self) -> usize {
         self.node.flow_debug_id()
     }
 
-    /// Returns an iterator over this node's children.
-    pub fn children(&self) -> ThreadSafeLayoutNodeChildrenIterator<'ln> {
+    fn children(&self) -> ThreadSafeLayoutNodeChildrenIterator<'ln, Self> {
         ThreadSafeLayoutNodeChildrenIterator::new(*self)
     }
 
-    /// If this is an element, accesses the element data. Fails if this is not an element node.
-    #[inline]
-    pub fn as_element(&self) -> ThreadSafeLayoutElement<'ln> {
+    fn as_element(&self) -> ThreadSafeLayoutElement<'ln> {
         unsafe {
             let element = match self.get_jsmanaged().downcast() {
                 Some(e) => e.unsafe_get(),
@@ -876,13 +1050,11 @@ impl<'ln> ThreadSafeLayoutNode<'ln> {
         }
     }
 
-    #[inline]
-    pub fn get_pseudo_element_type(&self) -> PseudoElementType<display::T> {
+    fn get_pseudo_element_type(&self) -> PseudoElementType<display::T> {
         self.pseudo
     }
 
-    #[inline]
-    pub fn get_before_pseudo(&self) -> Option<ThreadSafeLayoutNode<'ln>> {
+    fn get_before_pseudo(&self) -> Option<ThreadSafeLayoutNode<'ln>> {
         let layout_data_ref = self.borrow_layout_data();
         let node_layout_data_wrapper = layout_data_ref.as_ref().unwrap();
         node_layout_data_wrapper.data.before_style.as_ref().map(|style| {
@@ -890,8 +1062,7 @@ impl<'ln> ThreadSafeLayoutNode<'ln> {
         })
     }
 
-    #[inline]
-    pub fn get_after_pseudo(&self) -> Option<ThreadSafeLayoutNode<'ln>> {
+    fn get_after_pseudo(&self) -> Option<ThreadSafeLayoutNode<'ln>> {
         let layout_data_ref = self.borrow_layout_data();
         let node_layout_data_wrapper = layout_data_ref.as_ref().unwrap();
         node_layout_data_wrapper.data.after_style.as_ref().map(|style| {
@@ -899,61 +1070,15 @@ impl<'ln> ThreadSafeLayoutNode<'ln> {
         })
     }
 
-    /// Borrows the layout data without checking.
-    #[inline(always)]
-    fn borrow_layout_data_unchecked(&self) -> *const Option<LayoutDataWrapper> {
-        unsafe {
-            self.node.borrow_layout_data_unchecked()
-        }
-    }
-
-    /// Borrows the layout data immutably. Fails on a conflicting borrow.
-    ///
-    /// TODO(pcwalton): Make this private. It will let us avoid borrow flag checks in some cases.
-    #[inline(always)]
-    pub fn borrow_layout_data(&self) -> Ref<Option<LayoutDataWrapper>> {
+    fn borrow_layout_data(&self) -> Ref<Option<LayoutDataWrapper>> {
         self.node.borrow_layout_data()
     }
 
-    /// Borrows the layout data mutably. Fails on a conflicting borrow.
-    ///
-    /// TODO(pcwalton): Make this private. It will let us avoid borrow flag checks in some cases.
-    #[inline(always)]
-    pub fn mutate_layout_data(&self) -> RefMut<Option<LayoutDataWrapper>> {
+    fn mutate_layout_data(&self) -> RefMut<Option<LayoutDataWrapper>> {
         self.node.mutate_layout_data()
     }
 
-    /// Returns the style results for the given node. If CSS selector matching
-    /// has not yet been performed, fails.
-    #[inline]
-    pub fn style(&self) -> Ref<Arc<ComputedValues>> {
-        Ref::map(self.borrow_layout_data(), |layout_data_ref| {
-            let layout_data = layout_data_ref.as_ref().expect("no layout data");
-            let style = match self.get_pseudo_element_type() {
-                PseudoElementType::Before(_) => &layout_data.data.before_style,
-                PseudoElementType::After(_) => &layout_data.data.after_style,
-                PseudoElementType::Normal => &layout_data.shared_data.style,
-            };
-            style.as_ref().unwrap()
-        })
-    }
-
-    /// Removes the style from this node.
-    pub fn unstyle(self) {
-        let mut layout_data_ref = self.mutate_layout_data();
-        let layout_data = layout_data_ref.as_mut().expect("no layout data");
-
-        let style =
-            match self.get_pseudo_element_type() {
-                PseudoElementType::Before(_) => &mut layout_data.data.before_style,
-                PseudoElementType::After (_) => &mut layout_data.data.after_style,
-                PseudoElementType::Normal    => &mut layout_data.shared_data.style,
-            };
-
-        *style = None;
-    }
-
-    pub fn is_ignorable_whitespace(&self) -> bool {
+    fn is_ignorable_whitespace(&self) -> bool {
         unsafe {
             let text: LayoutJS<Text> = match self.get_jsmanaged().downcast() {
                 Some(text) => text,
@@ -980,24 +1105,7 @@ impl<'ln> ThreadSafeLayoutNode<'ln> {
         }
     }
 
-    /// Get the description of how to account for recent style changes.
-    /// This is a simple bitfield and fine to copy by value.
-    pub fn restyle_damage(self) -> RestyleDamage {
-        let layout_data_ref = self.borrow_layout_data();
-        layout_data_ref.as_ref().unwrap().data.restyle_damage
-    }
-
-    /// Set the restyle damage field.
-    pub fn set_restyle_damage(self, damage: RestyleDamage) {
-        let mut layout_data_ref = self.mutate_layout_data();
-        match *layout_data_ref {
-            Some(ref mut layout_data) => layout_data.data.restyle_damage = damage,
-            _ => panic!("no layout data for this node"),
-        }
-    }
-
-    /// Returns the layout data flags for this node.
-    pub fn flags(self) -> LayoutDataFlags {
+    fn flags(self) -> LayoutDataFlags {
         unsafe {
             match *self.borrow_layout_data_unchecked() {
                 None => panic!(),
@@ -1006,38 +1114,7 @@ impl<'ln> ThreadSafeLayoutNode<'ln> {
         }
     }
 
-    /// Adds the given flags to this node.
-    pub fn insert_flags(self, new_flags: LayoutDataFlags) {
-        let mut layout_data_ref = self.mutate_layout_data();
-        match *layout_data_ref {
-            Some(ref mut layout_data) => layout_data.data.flags.insert(new_flags),
-            _ => panic!("no layout data for this node"),
-        }
-    }
-
-    /// Removes the given flags from this node.
-    pub fn remove_flags(self, flags: LayoutDataFlags) {
-        let mut layout_data_ref = self.mutate_layout_data();
-        match *layout_data_ref {
-            Some(ref mut layout_data) => layout_data.data.flags.remove(flags),
-            _ => panic!("no layout data for this node"),
-        }
-    }
-
-    /// Returns true if this node contributes content. This is used in the implementation of
-    /// `empty_cells` per CSS 2.1 § 17.6.1.1.
-    pub fn is_content(&self) -> bool {
-        match self.type_id() {
-            Some(NodeTypeId::Element(..)) | Some(NodeTypeId::CharacterData(CharacterDataTypeId::Text(..))) => true,
-            _ => false
-        }
-    }
-
-    /// If this is a text node, generated content, or a form element, copies out
-    /// its content. Otherwise, panics.
-    ///
-    /// FIXME(pcwalton): This might have too much copying and/or allocation. Profile this.
-    pub fn text_content(&self) -> TextContent {
+    fn text_content(&self) -> TextContent {
         if self.pseudo != PseudoElementType::Normal {
             let layout_data_ref = self.borrow_layout_data();
             let data = &layout_data_ref.as_ref().unwrap().data;
@@ -1074,8 +1151,7 @@ impl<'ln> ThreadSafeLayoutNode<'ln> {
         panic!("not text!")
     }
 
-    /// If the insertion point is within this node, returns it. Otherwise, returns `None`.
-    pub fn insertion_point(&self) -> Option<CharIndex> {
+    fn insertion_point(&self) -> Option<CharIndex> {
         let this = unsafe {
             self.get_jsmanaged()
         };
@@ -1094,10 +1170,7 @@ impl<'ln> ThreadSafeLayoutNode<'ln> {
         None
     }
 
-    /// If this is an image element, returns its URL. If this is not an image element, fails.
-    ///
-    /// FIXME(pcwalton): Don't copy URLs.
-    pub fn image_url(&self) -> Option<Url> {
+    fn image_url(&self) -> Option<Url> {
         unsafe {
             self.get_jsmanaged().downcast()
                 .expect("not an image!")
@@ -1105,16 +1178,14 @@ impl<'ln> ThreadSafeLayoutNode<'ln> {
         }
     }
 
-    pub fn canvas_data(&self) -> Option<HTMLCanvasData> {
+    fn canvas_data(&self) -> Option<HTMLCanvasData> {
         unsafe {
             let canvas_element = self.get_jsmanaged().downcast();
             canvas_element.map(|canvas| canvas.data())
         }
     }
 
-    /// If this node is an iframe element, returns its pipeline ID. If this node is
-    /// not an iframe element, fails.
-    pub fn iframe_pipeline_id(&self) -> PipelineId {
+    fn iframe_pipeline_id(&self) -> PipelineId {
         use script::dom::htmliframeelement::HTMLIFrameElementLayoutMethods;
         unsafe {
             let iframe_element = self.get_jsmanaged().downcast::<HTMLIFrameElement>()
@@ -1123,65 +1194,56 @@ impl<'ln> ThreadSafeLayoutNode<'ln> {
         }
     }
 
-    pub fn get_colspan(&self) -> u32 {
+    fn get_colspan(&self) -> u32 {
         unsafe {
             self.get_jsmanaged().downcast::<Element>().unwrap().get_colspan()
         }
     }
 }
 
-pub struct ThreadSafeLayoutNodeChildrenIterator<'a> {
-    current_node: Option<ThreadSafeLayoutNode<'a>>,
-    parent_node: ThreadSafeLayoutNode<'a>,
+pub struct ThreadSafeLayoutNodeChildrenIterator<'ln, ConcreteNode: TThreadSafeLayoutNode<'ln>> {
+    current_node: Option<ConcreteNode>,
+    parent_node: ConcreteNode,
+    // Satisfy the compiler about the unused lifetime.
+    phantom: PhantomData<&'ln ()>,
 }
 
-impl<'a> ThreadSafeLayoutNodeChildrenIterator<'a> {
-    fn new(parent: ThreadSafeLayoutNode<'a>) -> ThreadSafeLayoutNodeChildrenIterator<'a> {
-        fn first_child(parent: ThreadSafeLayoutNode)
-                           -> Option<ThreadSafeLayoutNode> {
-            if parent.pseudo != PseudoElementType::Normal {
-                return None
-            }
-
-            parent.get_before_pseudo().or_else(|| {
-                unsafe {
-                    parent.get_jsmanaged().first_child_ref()
-                          .map(|node| parent.new_with_this_lifetime(&node))
-                }
-            })
-        }
-
+impl<'ln, ConcreteNode> ThreadSafeLayoutNodeChildrenIterator<'ln, ConcreteNode>
+                        where ConcreteNode: DangerousThreadSafeLayoutNode<'ln> {
+    fn new(parent: ConcreteNode) -> Self {
+        let first_child: Option<ConcreteNode> = match parent.get_pseudo_element_type() {
+            PseudoElementType::Normal => {
+                parent.get_before_pseudo().or_else(|| {
+                    unsafe { parent.dangerous_first_child() }
+                })
+            },
+            _ => None,
+        };
         ThreadSafeLayoutNodeChildrenIterator {
-            current_node: first_child(parent),
+            current_node: first_child,
             parent_node: parent,
+            phantom: PhantomData,
         }
     }
 }
 
-impl<'a> Iterator for ThreadSafeLayoutNodeChildrenIterator<'a> {
-    type Item = ThreadSafeLayoutNode<'a>;
-    fn next(&mut self) -> Option<ThreadSafeLayoutNode<'a>> {
+impl<'ln, ConcreteNode> Iterator for ThreadSafeLayoutNodeChildrenIterator<'ln, ConcreteNode>
+                                 where ConcreteNode: DangerousThreadSafeLayoutNode<'ln> {
+    type Item = ConcreteNode;
+    fn next(&mut self) -> Option<ConcreteNode> {
         let node = self.current_node.clone();
 
         if let Some(ref node) = node {
-            self.current_node = match node.pseudo {
+            self.current_node = match node.get_pseudo_element_type() {
                 PseudoElementType::Before(_) => {
-                    match unsafe { self.parent_node.get_jsmanaged().first_child_ref() } {
-                        Some(first) => {
-                            Some(unsafe {
-                                self.parent_node.new_with_this_lifetime(&first)
-                            })
-                        },
+                    match unsafe { self.parent_node.dangerous_first_child() } {
+                        Some(first) => Some(first),
                         None => self.parent_node.get_after_pseudo(),
                     }
                 },
                 PseudoElementType::Normal => {
-                    match unsafe { node.get_jsmanaged().next_sibling_ref() } {
-                        Some(next) => {
-                            Some(unsafe {
-                                self.parent_node.new_with_this_lifetime(&next)
-                            })
-                        },
+                    match unsafe { node.dangerous_next_sibling() } {
+                        Some(next) => Some(next),
                         None => self.parent_node.get_after_pseudo(),
                     }
                 },
@@ -1201,9 +1263,10 @@ pub struct ThreadSafeLayoutElement<'le> {
     element: &'le Element,
 }
 
-impl<'le> ThreadSafeLayoutElement<'le> {
-    #[inline]
-    pub fn get_attr(&self, namespace: &Namespace, name: &Atom) -> Option<&'le str> {
+impl<'le> TThreadSafeLayoutElement<'le> for ThreadSafeLayoutElement<'le> {
+    type ConcreteThreadSafeLayoutNode = ThreadSafeLayoutNode<'le>;
+
+    fn get_attr(&self, namespace: &Namespace, name: &Atom) -> Option<&'le str> {
         unsafe {
             self.element.get_attr_val_for_layout(namespace, name)
         }