Auto merge of #12861 - nox:impl-trait, r=Ms2ger

Clean up some iterators

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components/layout/flow.rs

@@ -31,7 +31,7 @@ use context::LayoutContext;
 use display_list_builder::DisplayListBuildState;
 use euclid::{Point2D, Rect, Size2D};
 use floats::{Floats, SpeculatedFloatPlacement};
-use flow_list::{FlowList, FlowListIterator, MutFlowListIterator};
+use flow_list::{FlowList, MutFlowListIterator};
 use flow_ref::{self, FlowRef, WeakFlowRef};
 use fragment::{Fragment, FragmentBorderBoxIterator, Overflow, SpecificFragmentInfo};
 use gfx::display_list::{ClippingRegion, StackingContext};
@@ -432,7 +432,7 @@ pub fn base<T: ?Sized + Flow>(this: &T) -> &BaseFlow {
 }
 
 /// Iterates over the children of this immutable flow.
-pub fn child_iter<'a>(flow: &'a Flow) -> FlowListIterator<'a> {
+pub fn child_iter<'a>(flow: &'a Flow) -> impl Iterator<Item = &'a Flow> {
     base(flow).children.iter()
 }
 

components/layout/flow_list.rs

@@ -13,10 +13,6 @@ pub struct FlowList {
     flows: LinkedList<FlowRef>,
 }
 
-pub struct FlowListIterator<'a> {
-    it: linked_list::Iter<'a, FlowRef>,
-}
-
 pub struct MutFlowListIterator<'a> {
     it: linked_list::IterMut<'a, FlowRef>,
 }
@@ -58,10 +54,8 @@ impl FlowList {
 
     /// Provide a forward iterator
     #[inline]
-    pub fn iter(&self) -> FlowListIterator {
-        FlowListIterator {
-            it: self.flows.iter(),
-        }
+    pub fn iter<'a>(&'a self) -> impl DoubleEndedIterator<Item = &'a Flow> {
+        self.flows.iter().map(|flow| &**flow)
     }
 
     /// Provide a forward iterator with mutable references
@@ -74,7 +68,8 @@ impl FlowList {
 
     /// Provide a forward iterator with FlowRef items
     #[inline]
-    pub fn iter_flow_ref_mut<'a>(&'a mut self) -> linked_list::IterMut<'a, FlowRef> {
+    pub fn iter_flow_ref_mut<'a>(&'a mut self)
+                                 -> impl DoubleEndedIterator<Item = &'a mut FlowRef> {
         self.flows.iter_mut()
     }
 
@@ -98,25 +93,6 @@ impl FlowList {
     }
 }
 
-impl<'a> Iterator for FlowListIterator<'a> {
-    type Item = &'a Flow;
-    #[inline]
-    fn next(&mut self) -> Option<&'a Flow> {
-        self.it.next().map(|x| &**x)
-    }
-
-    #[inline]
-    fn size_hint(&self) -> (usize, Option<usize>) {
-        self.it.size_hint()
-    }
-}
-
-impl<'a> DoubleEndedIterator for FlowListIterator<'a> {
-    fn next_back(&mut self) -> Option<&'a Flow> {
-        self.it.next_back().map(|x| &**x)
-    }
-}
-
 impl<'a> DoubleEndedIterator for MutFlowListIterator<'a> {
     fn next_back(&mut self) -> Option<&'a mut Flow> {
         self.it.next_back().map(flow_ref::deref_mut)

components/layout/lib.rs

@@ -4,6 +4,7 @@
 
 #![feature(box_patterns)]
 #![feature(box_syntax)]
+#![feature(conservative_impl_trait)]
 #![feature(custom_derive)]
 #![feature(nonzero)]
 #![feature(plugin)]