Implement type_id as inherent methods.

This implies LayoutNode no longer needs to return an Option, as it never
represents a pseudo-element.

Also, fixes lies in the documentation.

components/layout/construct.rs

@@ -41,7 +41,7 @@ use table_row::TableRowFlow;
 use table_rowgroup::TableRowGroupFlow;
 use table_wrapper::TableWrapperFlow;
 use text::TextRunScanner;
-use wrapper::{PostorderNodeMutTraversal, PseudoElementType, TLayoutNode, ThreadSafeLayoutNode};
+use wrapper::{PostorderNodeMutTraversal, PseudoElementType, ThreadSafeLayoutNode};
 
 use gfx::display_list::OpaqueNode;
 use script::dom::characterdata::CharacterDataTypeId;

components/layout/css/matching.rs

@@ -13,7 +13,7 @@ use data::{LayoutDataAccess, LayoutDataWrapper};
 use incremental::{self, RestyleDamage};
 use opaque_node::OpaqueNodeMethods;
 use smallvec::SmallVec16;
-use wrapper::{LayoutElement, LayoutNode, TLayoutNode};
+use wrapper::{LayoutElement, LayoutNode};
 
 use script::dom::characterdata::CharacterDataTypeId;
 use script::dom::node::NodeTypeId;
@@ -677,7 +677,7 @@ impl<'ln> MatchMethods for LayoutNode<'ln> {
             &mut None => panic!("no layout data"),
             &mut Some(ref mut layout_data) => {
                 match self.type_id() {
-                    Some(NodeTypeId::CharacterData(CharacterDataTypeId::Text)) => {
+                    NodeTypeId::CharacterData(CharacterDataTypeId::Text) => {
                         // Text nodes get a copy of the parent style. This ensures
                         // that during fragment construction any non-inherited
                         // CSS properties (such as vertical-align) are correctly

components/layout/wrapper.rs

@@ -80,10 +80,6 @@ pub trait TLayoutNode {
     /// Creates a new layout node with the same lifetime as this layout node.
     unsafe fn new_with_this_lifetime(&self, node: &LayoutJS<Node>) -> Self;
 
-    /// Returns the type ID of this node. Fails if this node is borrowed mutably. Returns `None`
-    /// if this is a pseudo-element; otherwise, returns `Some`.
-    fn type_id(&self) -> Option<NodeTypeId>;
-
     /// Returns the interior of this node as a `LayoutJS`. This is highly unsafe for layout to
     /// call and as such is marked `unsafe`.
     unsafe fn get_jsmanaged<'a>(&'a self) -> &'a LayoutJS<Node>;
@@ -118,12 +114,6 @@ impl<'ln> TLayoutNode for LayoutNode<'ln> {
         }
     }
 
-    fn type_id(&self) -> Option<NodeTypeId> {
-        unsafe {
-            Some(self.node.type_id_for_layout())
-        }
-    }
-
     unsafe fn get_jsmanaged<'a>(&'a self) -> &'a LayoutJS<Node> {
         &self.node
     }
@@ -136,6 +126,13 @@ impl<'ln> TLayoutNode for LayoutNode<'ln> {
 }
 
 impl<'ln> LayoutNode<'ln> {
+    /// Returns the type ID of this node.
+    pub fn type_id(&self) -> NodeTypeId {
+        unsafe {
+            self.node.type_id_for_layout()
+        }
+    }
+
     pub fn dump(self) {
         self.dump_indent(0);
     }
@@ -294,14 +291,14 @@ impl<'ln> TNode for LayoutNode<'ln> {
 
     fn is_element(&self) -> bool {
         match self.type_id() {
-            Some(NodeTypeId::Element(..)) => true,
+            NodeTypeId::Element(..) => true,
             _ => false
         }
     }
 
     fn is_document(&self) -> bool {
         match self.type_id() {
-            Some(NodeTypeId::Document(..)) => true,
+            NodeTypeId::Document(..) => true,
             _ => false
         }
     }
@@ -630,15 +627,6 @@ impl<'ln> TLayoutNode for ThreadSafeLayoutNode<'ln> {
         }
     }
 
-    /// Returns `None` if this is a pseudo-element.
-    fn type_id(&self) -> Option<NodeTypeId> {
-        if self.pseudo != PseudoElementType::Normal {
-            return None
-        }
-
-        self.node.type_id()
-    }
-
     unsafe fn get_jsmanaged<'a>(&'a self) -> &'a LayoutJS<Node> {
         self.node.get_jsmanaged()
     }
@@ -676,6 +664,16 @@ impl<'ln> ThreadSafeLayoutNode<'ln> {
         }
     }
 
+    /// 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> {
+        if self.pseudo != PseudoElementType::Normal {
+            return None
+        }
+
+        Some(self.node.type_id())
+    }
+
     pub fn debug_id(self) -> usize {
         self.node.debug_id()
     }