Remove a layer of Option on LayoutData

The individual fields are also Options, and LayoutData::new() is a fine default
value.

src/components/main/css/node_util.rs

@@ -27,10 +27,6 @@ impl<'self> NodeUtil<'self> for AbstractNode<LayoutView> {
      * stored in a box that can be overwritten
      */
     fn get_css_select_results(self) -> &'self CompleteSelectResults {
-        if !self.has_layout_data() {
-            fail!(~"style() called on a node without aux data!");
-        }
-
         do self.read_layout_data |layout_data| {
             match layout_data.style {
                 None => fail!(~"style() called on node without a style!"),
@@ -41,18 +37,11 @@ impl<'self> NodeUtil<'self> for AbstractNode<LayoutView> {
 
     /// Does this node have a computed style yet?
     fn have_css_select_results(self) -> bool {
-        if !self.has_layout_data() {
-            return false;
-        }
         self.read_layout_data(|data| data.style.is_some())
     }
 
     /// Update the computed style of an HTML element with a style specified by CSS.
     fn set_css_select_results(self, decl: CompleteSelectResults) {
-        if !self.has_layout_data() {
-            fail!(~"set_css_select_results() called on a node without aux data!");
-        }
-
         let cell = Cell::new(decl);
         self.write_layout_data(|data| data.style = Some(cell.take()));
     }
@@ -68,9 +57,6 @@ impl<'self> NodeUtil<'self> for AbstractNode<LayoutView> {
             RestyleDamage::none()
         };
 
-        if !self.has_layout_data() {
-            return default;
-        }
         do self.read_layout_data |layout_data| {
             layout_data.restyle_damage
                 .map(|&x| RestyleDamage::from_int(x))
@@ -80,10 +66,6 @@ impl<'self> NodeUtil<'self> for AbstractNode<LayoutView> {
 
     /// Set the restyle damage field.
     fn set_restyle_damage(self, damage: RestyleDamage) {
-        if !self.has_layout_data() {
-            fail!(~"set_restyle_damage() called on a node without aux data!");
-        }
-
         self.write_layout_data(|data| data.restyle_damage = Some(damage.to_int()));
     }
 }

src/components/main/layout/aux.rs

@@ -4,7 +4,7 @@
 
 //! Code for managing the layout data in the DOM.
 
-use script::dom::node::{AbstractNode, LayoutView, LayoutData};
+use script::dom::node::{AbstractNode, LayoutView};
 use servo_util::tree::TreeNodeRef;
 
 /// Functionality useful for querying the layout-specific data on DOM nodes.
@@ -14,21 +14,15 @@ pub trait LayoutAuxMethods {
 }
 
 impl LayoutAuxMethods for AbstractNode<LayoutView> {
-    /// If none exists, creates empty layout data for the node (the reader-auxiliary
-    /// box in the COW model) and populates it with an empty style object.
+    /// Resets layout data and styles for the node.
     fn initialize_layout_data(self) {
-        if self.has_layout_data() {
-            do self.write_layout_data |data| {
-                data.boxes.display_list = None;
-                data.boxes.range = None;
-            }
-        } else {
-            self.set_layout_data(LayoutData::new());
+        do self.write_layout_data |data| {
+            data.boxes.display_list = None;
+            data.boxes.range = None;
         }
     }
 
-    /// Initializes layout data and styles for a Node tree, if any nodes do not have
-    /// this data already.
+    /// Resets layout data and styles for a Node tree.
     fn initialize_style_for_subtree(self) {
         for n in self.traverse_preorder() {
             n.initialize_layout_data();

src/components/main/layout/layout_task.rs

@@ -322,7 +322,6 @@ impl LayoutTask {
                     let node: AbstractNode<LayoutView> = unsafe {
                         transmute(display_list.get().list[i].base().extra)
                     };
-                    assert!(node.has_layout_data(), "Node has display item but no layout data");
 
                     do node.write_layout_data |layout_data| {
                         layout_data.boxes.display_list = Some(display_list.clone());

src/components/script/dom/node.rs

@@ -16,7 +16,6 @@ use dom::htmliframeelement::HTMLIFrameElement;
 use dom::text::Text;
 
 use std::cast;
-use std::cell::Cell;
 use std::cast::transmute;
 use std::libc::c_void;
 use extra::arc::Arc;
@@ -90,7 +89,7 @@ pub struct Node<View> {
     owner_doc: Option<AbstractDocument>,
 
     /// Layout information. Only the layout task may touch this data.
-    priv layout_data: Option<LayoutData>,
+    priv layout_data: LayoutData,
 }
 
 /// The different types of nodes.
@@ -415,7 +414,7 @@ impl Node<ScriptView> {
 
             owner_doc: None,
 
-            layout_data: None,
+            layout_data: LayoutData::new(),
         }
     }
 
@@ -644,32 +643,19 @@ impl LayoutData {
 }
 
 impl AbstractNode<LayoutView> {
-    pub fn set_layout_data(self, data: LayoutData) {
-        let cell = Cell::new(data);
-        do self.with_mut_base |b| {
-            b.layout_data = Some(cell.take());
-        }
-    }
-
-    pub fn has_layout_data(self) -> bool {
-        do self.with_base |b| {
-            b.layout_data.is_some()
-        }
-    }
-
     // These accessors take a continuation rather than returning a reference, because
     // an AbstractNode doesn't have a lifetime parameter relating to the underlying
     // Node.  Also this makes it easier to switch to RWArc if we decide that is
     // necessary.
     pub fn read_layout_data<R>(self, blk: &fn(data: &LayoutData) -> R) -> R {
         do self.with_base |b| {
-            blk(b.layout_data.get_ref())
+            blk(&b.layout_data)
         }
     }
 
     pub fn write_layout_data<R>(self, blk: &fn(data: &mut LayoutData) -> R) -> R {
         do self.with_mut_base |b| {
-            blk(b.layout_data.get_mut_ref())
+            blk(&mut b.layout_data)
         }
     }
 }