Introduce the LayoutIterator newtype and return it for all children() methods in style and layout.

components/script/layout_wrapper.rs

@@ -58,7 +58,8 @@ use style::attr::AttrValue;
 use style::computed_values::display;
 use style::context::SharedStyleContext;
 use style::data::PrivateStyleData;
-use style::dom::{NodeInfo, OpaqueNode, PresentationalHintsSynthetizer, TDocument, TElement, TNode, UnsafeNode};
+use style::dom::{LayoutIterator, NodeInfo, OpaqueNode, PresentationalHintsSynthetizer, TDocument, TElement, TNode};
+use style::dom::UnsafeNode;
 use style::element_state::*;
 use style::properties::{ComputedValues, PropertyDeclarationBlock};
 use style::refcell::{Ref, RefCell, RefMut};
@@ -149,10 +150,10 @@ impl<'ln> TNode for ServoLayoutNode<'ln> {
         self.dump_style_indent(0);
     }
 
-    fn children(self) -> ServoChildrenIterator<'ln> {
+    fn children(self) -> LayoutIterator<ServoChildrenIterator<'ln>> {
-        ServoChildrenIterator {
+        LayoutIterator(ServoChildrenIterator {
             current: self.first_child(),
-        }
+        })
     }
 
     fn opaque(&self) -> OpaqueNode {
@@ -771,8 +772,8 @@ impl<'ln> ThreadSafeLayoutNode for ServoThreadSafeLayoutNode<'ln> {
         self.node.debug_id()
     }
 
-    fn children(&self) -> Self::ChildrenIterator {
+    fn children(&self) -> LayoutIterator<Self::ChildrenIterator> {
-        ThreadSafeLayoutNodeChildrenIterator::new(*self)
+        LayoutIterator(ThreadSafeLayoutNodeChildrenIterator::new(*self))
     }
 
     fn as_element(&self) -> ServoThreadSafeLayoutElement<'ln> {

components/script_layout_interface/wrapper_traits.rs

@@ -15,7 +15,7 @@ use std::sync::Arc;
 use string_cache::{Atom, Namespace};
 use style::computed_values::display;
 use style::context::SharedStyleContext;
-use style::dom::{NodeInfo, PresentationalHintsSynthetizer, TNode};
+use style::dom::{LayoutIterator, NodeInfo, PresentationalHintsSynthetizer, TNode};
 use style::dom::OpaqueNode;
 use style::properties::ServoComputedValues;
 use style::refcell::{Ref, RefCell};
@@ -81,10 +81,10 @@ pub trait LayoutNode: TNode {
     fn init_style_and_layout_data(&self, data: OpaqueStyleAndLayoutData);
     fn get_style_and_layout_data(&self) -> Option<OpaqueStyleAndLayoutData>;
 
-    fn rev_children(self) -> ReverseChildrenIterator<Self> {
+    fn rev_children(self) -> LayoutIterator<ReverseChildrenIterator<Self>> {
-        ReverseChildrenIterator {
+        LayoutIterator(ReverseChildrenIterator {
             current: self.last_child(),
-        }
+        })
     }
 
     fn traverse_preorder(self) -> TreeIterator<Self> {
@@ -169,7 +169,7 @@ pub trait ThreadSafeLayoutNode: Clone + Copy + NodeInfo + PartialEq + Sized {
     fn debug_id(self) -> usize;
 
     /// Returns an iterator over this node's children.
-    fn children(&self) -> Self::ChildrenIterator;
+    fn children(&self) -> LayoutIterator<Self::ChildrenIterator>;
 
     /// If this is an element, accesses the element data. Fails if this is not an element node.
     #[inline]

components/style/dom.rs

@@ -73,6 +73,14 @@ pub trait NodeInfo {
     fn is_text_node(&self) -> bool;
 }
 
+pub struct LayoutIterator<T>(pub T);
+impl<T, I> Iterator for LayoutIterator<T> where T: Iterator<Item=I>, I: NodeInfo {
+    type Item = I;
+    fn next(&mut self) -> Option<I> {
+        self.0.next()
+    }
+}
+
 pub trait TNode : Sized + Copy + Clone + NodeInfo {
     type ConcreteElement: TElement<ConcreteNode = Self, ConcreteDocument = Self::ConcreteDocument>;
     type ConcreteDocument: TDocument<ConcreteNode = Self, ConcreteElement = Self::ConcreteElement>;
@@ -87,7 +95,7 @@ pub trait TNode : Sized + Copy + Clone + NodeInfo {
     fn dump_style(self);
 
     /// Returns an iterator over this node's children.
-    fn children(self) -> Self::ConcreteChildrenIterator;
+    fn children(self) -> LayoutIterator<Self::ConcreteChildrenIterator>;
 
     /// Converts self into an `OpaqueNode`.
     fn opaque(&self) -> OpaqueNode;

ports/geckolib/wrapper.rs

@@ -39,8 +39,8 @@ use std::ops::BitOr;
 use std::ptr;
 use std::sync::Arc;
 use style::data::PrivateStyleData;
+use style::dom::{LayoutIterator, NodeInfo, TDocument, TElement, TNode, TRestyleDamage, UnsafeNode};
 use style::dom::{OpaqueNode, PresentationalHintsSynthetizer};
-use style::dom::{NodeInfo, TDocument, TElement, TNode, TRestyleDamage, UnsafeNode};
 use style::element_state::ElementState;
 use style::error_reporting::StdoutErrorReporter;
 use style::gecko_selector_impl::{GeckoSelectorImpl, NonTSPseudoClass, PseudoElement};
@@ -161,12 +161,12 @@ impl<'ln> TNode for GeckoNode<'ln> {
         unimplemented!()
     }
 
-    fn children(self) -> GeckoChildrenIterator<'ln> {
+    fn children(self) -> LayoutIterator<GeckoChildrenIterator<'ln>> {
         let maybe_iter = unsafe { Gecko_MaybeCreateStyleChildrenIterator(self.0) };
         if let Some(iter) = maybe_iter.into_owned_opt() {
-            GeckoChildrenIterator::GeckoIterator(iter)
+            LayoutIterator(GeckoChildrenIterator::GeckoIterator(iter))
         } else {
-            GeckoChildrenIterator::Current(self.first_child())
+            LayoutIterator(GeckoChildrenIterator::Current(self.first_child()))
         }
     }