Add some fmt::Debug implementations

1 files changed, 12 insertions, 1 deletions

diff --git a/components/script/layout_wrapper.rs b/components/script/layout_wrapper.rs
index cbf04b48e5b..431fe55f9b0 100644
--- a/components/script/layout_wrapper.rs
+++ b/components/script/layout_wrapper.rs
@@ -49,6 +49,7 @@ use script_layout_interface::{HTMLCanvasData, LayoutNodeType, TrustedNodeAddress
 use script_layout_interface::{OpaqueStyleAndLayoutData, PartialStyleAndLayoutData};
 use selectors::matching::{DeclarationBlock, ElementFlags};
 use selectors::parser::{AttrSelector, NamespaceConstraint};
+use std::fmt;
 use std::marker::PhantomData;
 use std::mem::{transmute, transmute_copy};
 use std::sync::Arc;
@@ -405,6 +406,16 @@ pub struct ServoLayoutElement<'le> {
     chain: PhantomData<&'le ()>,
 }
 
+impl<'le> fmt::Debug for ServoLayoutElement<'le> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        try!(write!(f, "<{}", self.element.local_name()));
+        if let &Some(ref id) = unsafe { &*self.element.id_attribute() } {
+            try!(write!(f, " id={}", id));
+        }
+        write!(f, ">")
+    }
+}
+
 impl<'le> PresentationalHintsSynthetizer for ServoLayoutElement<'le> {
     fn synthesize_presentational_hints_for_legacy_attributes<V>(&self, hints: &mut V)
         where V: Push<DeclarationBlock<Vec<PropertyDeclaration>>>
@@ -926,7 +937,7 @@ impl<ConcreteNode> Iterator for ThreadSafeLayoutNodeChildrenIterator<ConcreteNod
 
 /// A wrapper around elements that ensures layout can only
 /// ever access safe properties and cannot race on elements.
-#[derive(Copy, Clone)]
+#[derive(Copy, Clone, Debug)]
 pub struct ServoThreadSafeLayoutElement<'le> {
     element: &'le Element,
 }