auto merge of #2585 : ebalint/servo/2530, r=jdm

src/components/script/dom/bindings/codegen/CodegenRust.py

@@ -4339,7 +4339,7 @@ class CGBindingRoot(CGThing):
             'dom::bindings::proxyhandler::{FillPropertyDescriptor, GetExpandoObject}',
             'dom::bindings::proxyhandler::{getPropertyDescriptor}',
             'dom::bindings::str::ByteString',
-            'script_task::JSPageInfo',
+            'page::JSPageInfo',
             'libc',
             'servo_util::str::DOMString',
             'std::mem',
@@ -5214,7 +5214,7 @@ class GlobalGenRoots():
             'dom::bindings::codegen',
             'dom::bindings::js::{JS, JSRef}',
             'dom::window::Window',
-            'script_task::JSPageInfo',
+            'page::JSPageInfo',
         ])
 
     @staticmethod

src/components/script/dom/htmliframeelement.rs

@@ -14,7 +14,7 @@ use dom::htmlelement::HTMLElement;
 use dom::node::{Node, ElementNodeTypeId, window_from_node};
 use dom::virtualmethods::VirtualMethods;
 use dom::window::Window;
-use script_task::IterablePage;
+use page::IterablePage;
 use servo_msg::constellation_msg::{PipelineId, SubpageId};
 use servo_msg::constellation_msg::{IFrameSandboxed, IFrameUnsandboxed};
 use servo_msg::constellation_msg::{ConstellationChan, LoadIframeUrlMsg};

src/components/script/dom/location.rs

@@ -8,7 +8,7 @@ use dom::bindings::utils::{Reflectable, Reflector, reflect_dom_object};
 use dom::window::Window;
 use servo_util::str::DOMString;
 
-use script_task::{Page};
+use page::Page;
 use std::rc::Rc;
 
 use serialize::{Encoder, Encodable};

src/components/script/dom/window.rs

@@ -17,7 +17,8 @@ use dom::navigator::Navigator;
 use dom::performance::Performance;
 
 use layout_interface::{ReflowForDisplay, DocumentDamageLevel};
-use script_task::{ExitWindowMsg, FireTimerMsg, Page, ScriptChan, TriggerLoadMsg, TriggerFragmentMsg};
+use page::Page;
+use script_task::{ExitWindowMsg, FireTimerMsg, ScriptChan, TriggerLoadMsg, TriggerFragmentMsg};
 use servo_msg::compositor_msg::ScriptListener;
 use servo_net::image_cache_task::ImageCacheTask;
 use servo_util::str::DOMString;

src/components/script/html/hubbub_html_parser.rs

@@ -14,7 +14,7 @@ use dom::htmlformelement::HTMLFormElement;
 use dom::node::{ElementNodeTypeId, NodeHelpers, NodeMethods};
 use dom::types::*;
 use html::cssparse::{StylesheetProvenance, UrlProvenance, spawn_css_parser};
-use script_task::Page;
+use page::Page;
 
 use hubbub::hubbub;
 use hubbub::hubbub::{NullNs, HtmlNs, MathMlNs, SvgNs, XLinkNs, XmlNs, XmlNsNs};

src/components/script/page.rs

@@ -0,0 +1,436 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use dom::bindings::codegen::InheritTypes::{NodeCast, ElementCast};
+use dom::bindings::js::{JS, JSRef, Temporary};
+use dom::bindings::js::OptionalRootable;
+use dom::bindings::trace::{Traceable, Untraceable};
+use dom::bindings::utils::GlobalStaticData;
+use dom::document::{Document, DocumentMethods, DocumentHelpers};
+use dom::element::{Element, AttributeHandlers};
+use dom::node::{Node, NodeHelpers};
+use dom::window::Window;
+use layout_interface::{DocumentDamage};
+use layout_interface::{DocumentDamageLevel, HitTestQuery, HitTestResponse, LayoutQuery, MouseOverQuery, MouseOverResponse};
+use layout_interface::{LayoutChan, QueryMsg};
+use layout_interface::{Reflow, ReflowGoal, ReflowMsg};
+use layout_interface::UntrustedNodeAddress;
+use script_task::ScriptChan;
+
+use geom::point::Point2D;
+use geom::size::TypedSize2D;
+use js::rust::Cx;
+use servo_msg::compositor_msg::PerformingLayout;
+use servo_msg::compositor_msg::ScriptListener;
+use servo_msg::constellation_msg::ConstellationChan;
+use servo_msg::constellation_msg::{PipelineId, SubpageId};
+use servo_net::resource_task::ResourceTask;
+use servo_util::geometry::PagePx;
+use servo_util::namespace::Null;
+use servo_util::str::DOMString;
+use std::cell::{Cell, RefCell, Ref, RefMut};
+use std::comm::{channel, Receiver, Empty, Disconnected};
+use std::mem::replace;
+use std::rc::Rc;
+use url::Url;
+
+use serialize::{Encoder, Encodable};
+
+/// Encapsulates a handle to a frame and its associated layout information.
+#[deriving(Encodable)]
+pub struct Page {
+    /// Pipeline id associated with this page.
+    pub id: PipelineId,
+
+    /// Subpage id associated with this page, if any.
+    pub subpage_id: Option<SubpageId>,
+
+    /// Unique id for last reflow request; used for confirming completion reply.
+    pub last_reflow_id: Traceable<Cell<uint>>,
+
+    /// The outermost frame containing the document, window, and page URL.
+    pub frame: Traceable<RefCell<Option<Frame>>>,
+
+    /// A handle for communicating messages to the layout task.
+    pub layout_chan: Untraceable<LayoutChan>,
+
+    /// The port that we will use to join layout. If this is `None`, then layout is not running.
+    pub layout_join_port: Untraceable<RefCell<Option<Receiver<()>>>>,
+
+    /// What parts of the document are dirty, if any.
+    damage: Traceable<RefCell<Option<DocumentDamage>>>,
+
+    /// The current size of the window, in pixels.
+    pub window_size: Untraceable<Cell<TypedSize2D<PagePx, f32>>>,
+
+    js_info: Traceable<RefCell<Option<JSPageInfo>>>,
+
+    /// Cached copy of the most recent url loaded by the script
+    /// TODO(tkuehn): this currently does not follow any particular caching policy
+    /// and simply caches pages forever (!). The bool indicates if reflow is required
+    /// when reloading.
+    url: Untraceable<RefCell<Option<(Url, bool)>>>,
+
+    next_subpage_id: Untraceable<Cell<SubpageId>>,
+
+    /// Pending resize event, if any.
+    pub resize_event: Untraceable<Cell<Option<TypedSize2D<PagePx, f32>>>>,
+
+    /// Pending scroll to fragment event, if any
+    pub fragment_node: Cell<Option<JS<Element>>>,
+
+    /// Associated resource task for use by DOM objects like XMLHttpRequest
+    pub resource_task: Untraceable<ResourceTask>,
+
+    /// A handle for communicating messages to the constellation task.
+    pub constellation_chan: Untraceable<ConstellationChan>,
+
+    // Child Pages.
+    pub children: Traceable<RefCell<Vec<Rc<Page>>>>,
+}
+
+pub struct PageIterator {
+    stack: Vec<Rc<Page>>,
+}
+
+pub trait IterablePage {
+    fn iter(&self) -> PageIterator;
+    fn find(&self, id: PipelineId) -> Option<Rc<Page>>;
+}
+
+impl IterablePage for Rc<Page> {
+    fn iter(&self) -> PageIterator {
+        PageIterator {
+            stack: vec!(self.clone()),
+        }
+    }
+    fn find(&self, id: PipelineId) -> Option<Rc<Page>> {
+        if self.id == id { return Some(self.clone()); }
+        for page in self.children.deref().borrow().iter() {
+            let found = page.find(id);
+            if found.is_some() { return found; }
+        }
+        None
+    }
+
+}
+
+impl Page {
+    pub fn new(id: PipelineId, subpage_id: Option<SubpageId>,
+           layout_chan: LayoutChan,
+           window_size: TypedSize2D<PagePx, f32>, resource_task: ResourceTask,
+           constellation_chan: ConstellationChan,
+           js_context: Rc<Cx>) -> Page {
+        let js_info = JSPageInfo {
+            dom_static: GlobalStaticData(),
+            js_context: Untraceable::new(js_context),
+        };
+        Page {
+            id: id,
+            subpage_id: subpage_id,
+            frame: Traceable::new(RefCell::new(None)),
+            layout_chan: Untraceable::new(layout_chan),
+            layout_join_port: Untraceable::new(RefCell::new(None)),
+            damage: Traceable::new(RefCell::new(None)),
+            window_size: Untraceable::new(Cell::new(window_size)),
+            js_info: Traceable::new(RefCell::new(Some(js_info))),
+            url: Untraceable::new(RefCell::new(None)),
+            next_subpage_id: Untraceable::new(Cell::new(SubpageId(0))),
+            resize_event: Untraceable::new(Cell::new(None)),
+            fragment_node: Cell::new(None),
+            last_reflow_id: Traceable::new(Cell::new(0)),
+            resource_task: Untraceable::new(resource_task),
+            constellation_chan: Untraceable::new(constellation_chan),
+            children: Traceable::new(RefCell::new(vec!())),
+        }
+    }
+
+    // must handle root case separately
+    pub fn remove(&self, id: PipelineId) -> Option<Rc<Page>> {
+        let remove_idx = {
+            self.children
+                .deref()
+                .borrow_mut()
+                .mut_iter()
+                .enumerate()
+                .find(|&(_idx, ref page_tree)| {
+                    // FIXME: page_tree has a lifetime such that it's unusable for anything.
+                    let page_tree_id = page_tree.id;
+                    page_tree_id == id
+                })
+                .map(|(idx, _)| idx)
+        };
+        match remove_idx {
+            Some(idx) => return Some(self.children.deref().borrow_mut().remove(idx).unwrap()),
+            None => {
+                for page_tree in self.children.deref().borrow_mut().mut_iter() {
+                    match page_tree.remove(id) {
+                        found @ Some(_) => return found,
+                        None => (), // keep going...
+                    }
+                }
+            }
+        }
+        None
+    }
+}
+
+impl Iterator<Rc<Page>> for PageIterator {
+    fn next(&mut self) -> Option<Rc<Page>> {
+        if !self.stack.is_empty() {
+            let next = self.stack.pop().unwrap();
+            for child in next.children.deref().borrow().iter() {
+                self.stack.push(child.clone());
+            }
+            Some(next.clone())
+        } else {
+            None
+        }
+    }
+}
+
+impl Page {
+    pub fn mut_js_info<'a>(&'a self) -> RefMut<'a, Option<JSPageInfo>> {
+        self.js_info.deref().borrow_mut()
+    }
+
+    pub fn js_info<'a>(&'a self) -> Ref<'a, Option<JSPageInfo>> {
+        self.js_info.deref().borrow()
+    }
+
+    pub fn url<'a>(&'a self) -> Ref<'a, Option<(Url, bool)>> {
+        self.url.deref().borrow()
+    }
+
+    pub fn mut_url<'a>(&'a self) -> RefMut<'a, Option<(Url, bool)>> {
+        self.url.deref().borrow_mut()
+    }
+
+    pub fn frame<'a>(&'a self) -> Ref<'a, Option<Frame>> {
+        self.frame.deref().borrow()
+    }
+
+    pub fn mut_frame<'a>(&'a self) -> RefMut<'a, Option<Frame>> {
+        self.frame.deref().borrow_mut()
+    }
+
+    pub fn get_next_subpage_id(&self) -> SubpageId {
+        let subpage_id = self.next_subpage_id.deref().get();
+        let SubpageId(id_num) = subpage_id;
+        self.next_subpage_id.deref().set(SubpageId(id_num + 1));
+        subpage_id
+    }
+
+    /// Adds the given damage.
+    pub fn damage(&self, level: DocumentDamageLevel) {
+        let root = match *self.frame() {
+            None => return,
+            Some(ref frame) => frame.document.root().GetDocumentElement()
+        };
+        match root.root() {
+            None => {},
+            Some(root) => {
+                let root: &JSRef<Node> = NodeCast::from_ref(&*root);
+                let mut damage = *self.damage.deref().borrow_mut();
+                match damage {
+                    None => {}
+                    Some(ref mut damage) => {
+                        // FIXME(pcwalton): This is wrong. We should trace up to the nearest ancestor.
+                        damage.root = root.to_trusted_node_address();
+                        damage.level.add(level);
+                        return
+                    }
+                }
+
+                *self.damage.deref().borrow_mut() = Some(DocumentDamage {
+                    root: root.to_trusted_node_address(),
+                    level: level,
+                })
+            }
+        };
+    }
+
+    pub fn get_url(&self) -> Url {
+        self.url().get_ref().ref0().clone()
+    }
+
+    /// Sends a ping to layout and waits for the response. The response will arrive when the
+    /// layout task has finished any pending request messages.
+    pub fn join_layout(&self) {
+        let mut layout_join_port = self.layout_join_port.deref().borrow_mut();
+        if layout_join_port.is_some() {
+            let join_port = replace(&mut *layout_join_port, None);
+            match join_port {
+                Some(ref join_port) => {
+                    match join_port.try_recv() {
+                        Err(Empty) => {
+                            info!("script: waiting on layout");
+                            join_port.recv();
+                        }
+                        Ok(_) => {}
+                        Err(Disconnected) => {
+                            fail!("Layout task failed while script was waiting for a result.");
+                        }
+                    }
+
+                    debug!("script: layout joined")
+                }
+                None => fail!("reader forked but no join port?"),
+            }
+        }
+    }
+
+    /// Sends the given query to layout.
+    pub fn query_layout<T: Send>(&self,
+                                 query: LayoutQuery,
+                                 response_port: Receiver<T>)
+                                 -> T {
+        self.join_layout();
+        let LayoutChan(ref chan) = *self.layout_chan;
+        chan.send(QueryMsg(query));
+        response_port.recv()
+    }
+
+    /// Reflows the page if it's possible to do so. This method will wait until the layout task has
+    /// completed its current action, join the layout task, and then request a new layout run. It
+    /// won't wait for the new layout computation to finish.
+    ///
+    /// If there is no window size yet, the page is presumed invisible and no reflow is performed.
+    ///
+    /// This function fails if there is no root frame.
+    pub fn reflow(&self,
+                  goal: ReflowGoal,
+                  script_chan: ScriptChan,
+                  compositor: &ScriptListener) {
+
+        let root = match *self.frame() {
+            None => return,
+            Some(ref frame) => {
+                frame.document.root().GetDocumentElement()
+            }
+        };
+
+        match root.root() {
+            None => {},
+            Some(root) => {
+                debug!("script: performing reflow for goal {:?}", goal);
+
+                // Now, join the layout so that they will see the latest changes we have made.
+                self.join_layout();
+
+                // Tell the user that we're performing layout.
+                compositor.set_ready_state(PerformingLayout);
+
+                // Layout will let us know when it's done.
+                let (join_chan, join_port) = channel();
+                let mut layout_join_port = self.layout_join_port.deref().borrow_mut();
+                *layout_join_port = Some(join_port);
+
+                let last_reflow_id = self.last_reflow_id.deref();
+                last_reflow_id.set(last_reflow_id.get() + 1);
+
+                let root: &JSRef<Node> = NodeCast::from_ref(&*root);
+                let mut damage = self.damage.deref().borrow_mut();
+                let window_size = self.window_size.deref().get();
+
+                // Send new document and relevant styles to layout.
+                let reflow = box Reflow {
+                    document_root: root.to_trusted_node_address(),
+                    url: self.get_url(),
+                    goal: goal,
+                    window_size: window_size,
+                    script_chan: script_chan,
+                    script_join_chan: join_chan,
+                    damage: replace(&mut *damage, None).unwrap(),
+                    id: last_reflow_id.get(),
+                };
+
+                let LayoutChan(ref chan) = *self.layout_chan;
+                chan.send(ReflowMsg(reflow));
+
+                debug!("script: layout forked")
+            }
+        }
+    }
+
+    /// Attempt to find a named element in this page's document.
+    pub fn find_fragment_node(&self, fragid: DOMString) -> Option<Temporary<Element>> {
+        let document = self.frame().get_ref().document.root();
+        match document.deref().GetElementById(fragid.to_string()) {
+            Some(node) => Some(node),
+            None => {
+                let doc_node: &JSRef<Node> = NodeCast::from_ref(&*document);
+                let mut anchors = doc_node.traverse_preorder()
+                                          .filter(|node| node.is_anchor_element());
+                anchors.find(|node| {
+                    let elem: &JSRef<Element> = ElementCast::to_ref(node).unwrap();
+                    elem.get_attribute(Null, "name").root().map_or(false, |attr| {
+                        attr.deref().value_ref() == fragid.as_slice()
+                    })
+                }).map(|node| Temporary::from_rooted(ElementCast::to_ref(&node).unwrap()))
+            }
+        }
+    }
+
+    pub fn hit_test(&self, point: &Point2D<f32>) -> Option<UntrustedNodeAddress> {
+        let frame = self.frame();
+        let document = frame.get_ref().document.root();
+        let root = document.deref().GetDocumentElement().root();
+        if root.is_none() {
+            return None;
+        }
+        let root = root.unwrap();
+        let root: &JSRef<Node> = NodeCast::from_ref(&*root);
+        let (chan, port) = channel();
+        let address = match self.query_layout(HitTestQuery(root.to_trusted_node_address(), *point, chan), port) {
+            Ok(HitTestResponse(node_address)) => {
+                Some(node_address)
+            }
+            Err(()) => {
+                debug!("layout query error");
+                None
+            }
+        };
+        address
+    }
+
+    pub fn get_nodes_under_mouse(&self, point: &Point2D<f32>) -> Option<Vec<UntrustedNodeAddress>> {
+        let frame = self.frame();
+        let document = frame.get_ref().document.root();
+        let root = document.deref().GetDocumentElement().root();
+        if root.is_none() {
+            return None;
+        }
+        let root = root.unwrap();
+        let root: &JSRef<Node> = NodeCast::from_ref(&*root);
+        let (chan, port) = channel();
+        let address = match self.query_layout(MouseOverQuery(root.to_trusted_node_address(), *point, chan), port) {
+            Ok(MouseOverResponse(node_address)) => {
+                Some(node_address)
+            }
+            Err(()) => {
+                None
+            }
+        };
+        address
+    }
+}
+
+/// Information for one frame in the browsing context.
+#[deriving(Encodable)]
+pub struct Frame {
+    /// The document for this frame.
+    pub document: JS<Document>,
+    /// The window object for this frame.
+    pub window: JS<Window>,
+}
+
+/// Encapsulation of the javascript information associated with each frame.
+#[deriving(Encodable)]
+pub struct JSPageInfo {
+    /// Global static data related to the DOM.
+    pub dom_static: GlobalStaticData,
+    /// The JavaScript context.
+    pub js_context: Untraceable<Rc<Cx>>,
+}

src/components/script/script.rs

@@ -181,4 +181,5 @@ pub mod html {
 }
 
 pub mod layout_interface;
+pub mod page;
 pub mod script_task;

src/components/script/script_task.rs

@@ -6,14 +6,13 @@
 //! and layout tasks.
 
 use dom::bindings::codegen::RegisterBindings;
-use dom::bindings::codegen::InheritTypes::{EventTargetCast, NodeCast, ElementCast, EventCast};
+use dom::bindings::codegen::InheritTypes::{EventTargetCast, NodeCast, EventCast};
 use dom::bindings::js::{JS, JSRef, RootCollection, Temporary, OptionalSettable};
 use dom::bindings::js::OptionalRootable;
-use dom::bindings::trace::{Traceable, Untraceable};
-use dom::bindings::utils::{Reflectable, GlobalStaticData};
+use dom::bindings::utils::Reflectable;
 use dom::bindings::utils::{wrap_for_same_compartment, pre_wrap};
-use dom::document::{Document, HTMLDocument, DocumentMethods, DocumentHelpers};
-use dom::element::{Element, AttributeHandlers};
+use dom::document::{Document, HTMLDocument, DocumentHelpers};
+use dom::element::{Element};
 use dom::event::{Event_, ResizeEvent, ReflowEvent, ClickEvent, MouseDownEvent, MouseMoveEvent, MouseUpEvent};
 use dom::event::Event;
 use dom::uievent::UIEvent;
@@ -25,13 +24,12 @@ use dom::xmlhttprequest::{TrustedXHRAddress, XMLHttpRequest, XHRProgress};
 use html::hubbub_html_parser::HtmlParserResult;
 use html::hubbub_html_parser::{HtmlDiscoveredStyle, HtmlDiscoveredScript};
 use html::hubbub_html_parser;
-use layout_interface::{AddStylesheetMsg, DocumentDamage};
-use layout_interface::{DocumentDamageLevel, HitTestQuery, HitTestResponse, LayoutQuery, MouseOverQuery, MouseOverResponse};
-use layout_interface::{LayoutChan, MatchSelectorsDocumentDamage, QueryMsg};
-use layout_interface::{Reflow, ReflowDocumentDamage, ReflowForDisplay, ReflowGoal, ReflowMsg};
+use layout_interface::AddStylesheetMsg;
+use layout_interface::{LayoutChan, MatchSelectorsDocumentDamage};
+use layout_interface::{ReflowDocumentDamage, ReflowForDisplay};
 use layout_interface::ContentChangedDocumentDamage;
-use layout_interface::UntrustedNodeAddress;
 use layout_interface;
+use page::{Page, IterablePage, Frame};
 
 use geom::point::Point2D;
 use geom::size::TypedSize2D;
@@ -42,7 +40,7 @@ use js::jsval::NullValue;
 use js::rust::{Cx, RtUtils};
 use js::rust::with_compartment;
 use js;
-use servo_msg::compositor_msg::{FinishedLoading, LayerId, Loading, PerformingLayout};
+use servo_msg::compositor_msg::{FinishedLoading, LayerId, Loading};
 use servo_msg::compositor_msg::{ScriptListener};
 use servo_msg::constellation_msg::{ConstellationChan, LoadCompleteMsg, LoadUrlMsg, NavigationDirection};
 use servo_msg::constellation_msg::{PipelineId, SubpageId, Failure, FailureMsg};
@@ -51,10 +49,8 @@ use servo_net::image_cache_task::ImageCacheTask;
 use servo_net::resource_task::ResourceTask;
 use servo_util::geometry::{PagePx, to_frac_px};
 use servo_util::task::send_on_failure;
-use servo_util::namespace::Null;
-use servo_util::str::DOMString;
-use std::cell::{Cell, RefCell, Ref, RefMut};
-use std::comm::{channel, Sender, Receiver, Empty, Disconnected};
+use std::cell::RefCell;
+use std::comm::{channel, Sender, Receiver};
 use std::mem::replace;
 use std::ptr;
 use std::rc::Rc;
@@ -120,403 +116,6 @@ impl ScriptChan {
     }
 }
 
-/// Encapsulates a handle to a frame and its associated layout information.
-#[deriving(Encodable)]
-pub struct Page {
-    /// Pipeline id associated with this page.
-    pub id: PipelineId,
-
-    /// Subpage id associated with this page, if any.
-    pub subpage_id: Option<SubpageId>,
-
-    /// Unique id for last reflow request; used for confirming completion reply.
-    last_reflow_id: Traceable<Cell<uint>>,
-
-    /// The outermost frame containing the document, window, and page URL.
-    pub frame: Traceable<RefCell<Option<Frame>>>,
-
-    /// A handle for communicating messages to the layout task.
-    pub layout_chan: Untraceable<LayoutChan>,
-
-    /// The port that we will use to join layout. If this is `None`, then layout is not running.
-    layout_join_port: Untraceable<RefCell<Option<Receiver<()>>>>,
-
-    /// What parts of the document are dirty, if any.
-    damage: Traceable<RefCell<Option<DocumentDamage>>>,
-
-    /// The current size of the window, in pixels.
-    window_size: Untraceable<Cell<TypedSize2D<PagePx, f32>>>,
-
-    js_info: Traceable<RefCell<Option<JSPageInfo>>>,
-
-    /// Cached copy of the most recent url loaded by the script
-    /// TODO(tkuehn): this currently does not follow any particular caching policy
-    /// and simply caches pages forever (!). The bool indicates if reflow is required
-    /// when reloading.
-    url: Untraceable<RefCell<Option<(Url, bool)>>>,
-
-    next_subpage_id: Untraceable<Cell<SubpageId>>,
-
-    /// Pending resize event, if any.
-    resize_event: Untraceable<Cell<Option<TypedSize2D<PagePx, f32>>>>,
-
-    /// Pending scroll to fragment event, if any
-    fragment_node: Cell<Option<JS<Element>>>,
-
-    /// Associated resource task for use by DOM objects like XMLHttpRequest
-    pub resource_task: Untraceable<ResourceTask>,
-
-    /// A handle for communicating messages to the constellation task.
-    pub constellation_chan: Untraceable<ConstellationChan>,
-
-    // Child Pages.
-    pub children: Traceable<RefCell<Vec<Rc<Page>>>>,
-}
-
-pub struct PageIterator {
-    stack: Vec<Rc<Page>>,
-}
-
-pub trait IterablePage {
-    fn iter(&self) -> PageIterator;
-    fn find(&self, id: PipelineId) -> Option<Rc<Page>>;
-}
-impl IterablePage for Rc<Page> {
-    fn iter(&self) -> PageIterator {
-        PageIterator {
-            stack: vec!(self.clone()),
-        }
-    }
-    fn find(&self, id: PipelineId) -> Option<Rc<Page>> {
-        if self.id == id { return Some(self.clone()); }
-        for page in self.children.deref().borrow().iter() {
-            let found = page.find(id);
-            if found.is_some() { return found; }
-        }
-        None
-    }
-
-}
-
-impl Page {
-    fn new(id: PipelineId, subpage_id: Option<SubpageId>,
-           layout_chan: LayoutChan,
-           window_size: TypedSize2D<PagePx, f32>, resource_task: ResourceTask,
-           constellation_chan: ConstellationChan,
-           js_context: Rc<Cx>) -> Page {
-        let js_info = JSPageInfo {
-            dom_static: GlobalStaticData(),
-            js_context: Untraceable::new(js_context),
-        };
-        Page {
-            id: id,
-            subpage_id: subpage_id,
-            frame: Traceable::new(RefCell::new(None)),
-            layout_chan: Untraceable::new(layout_chan),
-            layout_join_port: Untraceable::new(RefCell::new(None)),
-            damage: Traceable::new(RefCell::new(None)),
-            window_size: Untraceable::new(Cell::new(window_size)),
-            js_info: Traceable::new(RefCell::new(Some(js_info))),
-            url: Untraceable::new(RefCell::new(None)),
-            next_subpage_id: Untraceable::new(Cell::new(SubpageId(0))),
-            resize_event: Untraceable::new(Cell::new(None)),
-            fragment_node: Cell::new(None),
-            last_reflow_id: Traceable::new(Cell::new(0)),
-            resource_task: Untraceable::new(resource_task),
-            constellation_chan: Untraceable::new(constellation_chan),
-            children: Traceable::new(RefCell::new(vec!())),
-        }
-    }
-
-    // must handle root case separately
-    pub fn remove(&self, id: PipelineId) -> Option<Rc<Page>> {
-        let remove_idx = {
-            self.children
-                .deref()
-                .borrow_mut()
-                .mut_iter()
-                .enumerate()
-                .find(|&(_idx, ref page_tree)| {
-                    // FIXME: page_tree has a lifetime such that it's unusable for anything.
-                    let page_tree_id = page_tree.id;
-                    page_tree_id == id
-                })
-                .map(|(idx, _)| idx)
-        };
-        match remove_idx {
-            Some(idx) => return Some(self.children.deref().borrow_mut().remove(idx).unwrap()),
-            None => {
-                for page_tree in self.children.deref().borrow_mut().mut_iter() {
-                    match page_tree.remove(id) {
-                        found @ Some(_) => return found,
-                        None => (), // keep going...
-                    }
-                }
-            }
-        }
-        None
-    }
-}
-
-impl Iterator<Rc<Page>> for PageIterator {
-    fn next(&mut self) -> Option<Rc<Page>> {
-        if !self.stack.is_empty() {
-            let next = self.stack.pop().unwrap();
-            for child in next.children.deref().borrow().iter() {
-                self.stack.push(child.clone());
-            }
-            Some(next.clone())
-        } else {
-            None
-        }
-    }
-}
-
-impl Page {
-    pub fn mut_js_info<'a>(&'a self) -> RefMut<'a, Option<JSPageInfo>> {
-        self.js_info.deref().borrow_mut()
-    }
-
-    pub fn js_info<'a>(&'a self) -> Ref<'a, Option<JSPageInfo>> {
-        self.js_info.deref().borrow()
-    }
-
-    pub fn url<'a>(&'a self) -> Ref<'a, Option<(Url, bool)>> {
-        self.url.deref().borrow()
-    }
-
-    pub fn mut_url<'a>(&'a self) -> RefMut<'a, Option<(Url, bool)>> {
-        self.url.deref().borrow_mut()
-    }
-
-    pub fn frame<'a>(&'a self) -> Ref<'a, Option<Frame>> {
-        self.frame.deref().borrow()
-    }
-
-    pub fn mut_frame<'a>(&'a self) -> RefMut<'a, Option<Frame>> {
-        self.frame.deref().borrow_mut()
-    }
-
-    pub fn get_next_subpage_id(&self) -> SubpageId {
-        let subpage_id = self.next_subpage_id.deref().get();
-        let SubpageId(id_num) = subpage_id;
-        self.next_subpage_id.deref().set(SubpageId(id_num + 1));
-        subpage_id
-    }
-
-    /// Adds the given damage.
-    pub fn damage(&self, level: DocumentDamageLevel) {
-        let root = match *self.frame() {
-            None => return,
-            Some(ref frame) => frame.document.root().GetDocumentElement()
-        };
-        match root.root() {
-            None => {},
-            Some(root) => {
-                let root: &JSRef<Node> = NodeCast::from_ref(&*root);
-                let mut damage = *self.damage.deref().borrow_mut();
-                match damage {
-                    None => {}
-                    Some(ref mut damage) => {
-                        // FIXME(pcwalton): This is wrong. We should trace up to the nearest ancestor.
-                        damage.root = root.to_trusted_node_address();
-                        damage.level.add(level);
-                        return
-                    }
-                }
-
-                *self.damage.deref().borrow_mut() = Some(DocumentDamage {
-                    root: root.to_trusted_node_address(),
-                    level: level,
-                })
-            }
-        };
-    }
-
-    pub fn get_url(&self) -> Url {
-        self.url().get_ref().ref0().clone()
-    }
-
-    /// Sends a ping to layout and waits for the response. The response will arrive when the
-    /// layout task has finished any pending request messages.
-    pub fn join_layout(&self) {
-        let mut layout_join_port = self.layout_join_port.deref().borrow_mut();
-        if layout_join_port.is_some() {
-            let join_port = replace(&mut *layout_join_port, None);
-            match join_port {
-                Some(ref join_port) => {
-                    match join_port.try_recv() {
-                        Err(Empty) => {
-                            info!("script: waiting on layout");
-                            join_port.recv();
-                        }
-                        Ok(_) => {}
-                        Err(Disconnected) => {
-                            fail!("Layout task failed while script was waiting for a result.");
-                        }
-                    }
-
-                    debug!("script: layout joined")
-                }
-                None => fail!("reader forked but no join port?"),
-            }
-        }
-    }
-
-    /// Sends the given query to layout.
-    pub fn query_layout<T: Send>(&self,
-                                 query: LayoutQuery,
-                                 response_port: Receiver<T>)
-                                 -> T {
-        self.join_layout();
-        let LayoutChan(ref chan) = *self.layout_chan;
-        chan.send(QueryMsg(query));
-        response_port.recv()
-    }
-
-    /// Reflows the page if it's possible to do so. This method will wait until the layout task has
-    /// completed its current action, join the layout task, and then request a new layout run. It
-    /// won't wait for the new layout computation to finish.
-    ///
-    /// If there is no window size yet, the page is presumed invisible and no reflow is performed.
-    ///
-    /// This function fails if there is no root frame.
-    pub fn reflow(&self,
-                  goal: ReflowGoal,
-                  script_chan: ScriptChan,
-                  compositor: &ScriptListener) {
-
-        let root = match *self.frame() {
-            None => return,
-            Some(ref frame) => {
-                frame.document.root().GetDocumentElement()
-            }
-        };
-
-        match root.root() {
-            None => {},
-            Some(root) => {
-                debug!("script: performing reflow for goal {:?}", goal);
-
-                // Now, join the layout so that they will see the latest changes we have made.
-                self.join_layout();
-
-                // Tell the user that we're performing layout.
-                compositor.set_ready_state(PerformingLayout);
-
-                // Layout will let us know when it's done.
-                let (join_chan, join_port) = channel();
-                let mut layout_join_port = self.layout_join_port.deref().borrow_mut();
-                *layout_join_port = Some(join_port);
-
-                let last_reflow_id = self.last_reflow_id.deref();
-                last_reflow_id.set(last_reflow_id.get() + 1);
-
-                let root: &JSRef<Node> = NodeCast::from_ref(&*root);
-                let mut damage = self.damage.deref().borrow_mut();
-                let window_size = self.window_size.deref().get();
-
-                // Send new document and relevant styles to layout.
-                let reflow = box Reflow {
-                    document_root: root.to_trusted_node_address(),
-                    url: self.get_url(),
-                    goal: goal,
-                    window_size: window_size,
-                    script_chan: script_chan,
-                    script_join_chan: join_chan,
-                    damage: replace(&mut *damage, None).unwrap(),
-                    id: last_reflow_id.get(),
-                };
-
-                let LayoutChan(ref chan) = *self.layout_chan;
-                chan.send(ReflowMsg(reflow));
-
-                debug!("script: layout forked")
-            }
-        }
-    }
-
-    /// Attempt to find a named element in this page's document.
-    fn find_fragment_node(&self, fragid: DOMString) -> Option<Temporary<Element>> {
-        let document = self.frame().get_ref().document.root();
-        match document.deref().GetElementById(fragid.to_string()) {
-            Some(node) => Some(node),
-            None => {
-                let doc_node: &JSRef<Node> = NodeCast::from_ref(&*document);
-                let mut anchors = doc_node.traverse_preorder()
-                                          .filter(|node| node.is_anchor_element());
-                anchors.find(|node| {
-                    let elem: &JSRef<Element> = ElementCast::to_ref(node).unwrap();
-                    elem.get_attribute(Null, "name").root().map_or(false, |attr| {
-                        attr.deref().value_ref() == fragid.as_slice()
-                    })
-                }).map(|node| Temporary::from_rooted(ElementCast::to_ref(&node).unwrap()))
-            }
-        }
-    }
-
-    pub fn hit_test(&self, point: &Point2D<f32>) -> Option<UntrustedNodeAddress> {
-        let frame = self.frame();
-        let document = frame.get_ref().document.root();
-        let root = document.deref().GetDocumentElement().root();
-        if root.is_none() {
-            return None;
-        }
-        let root = root.unwrap();
-        let root: &JSRef<Node> = NodeCast::from_ref(&*root);
-        let (chan, port) = channel();
-        let address = match self.query_layout(HitTestQuery(root.to_trusted_node_address(), *point, chan), port) {
-            Ok(HitTestResponse(node_address)) => {
-                Some(node_address)
-            }
-            Err(()) => {
-                debug!("layout query error");
-                None
-            }
-        };
-        address
-    }
-
-    pub fn get_nodes_under_mouse(&self, point: &Point2D<f32>) -> Option<Vec<UntrustedNodeAddress>> {
-        let frame = self.frame();
-        let document = frame.get_ref().document.root();
-        let root = document.deref().GetDocumentElement().root();
-        if root.is_none() {
-            return None;
-        }
-        let root = root.unwrap();
-        let root: &JSRef<Node> = NodeCast::from_ref(&*root);
-        let (chan, port) = channel();
-        let address = match self.query_layout(MouseOverQuery(root.to_trusted_node_address(), *point, chan), port) {
-            Ok(MouseOverResponse(node_address)) => {
-                Some(node_address)
-            }
-            Err(()) => {
-                None
-            }
-        };
-        address
-    }
-}
-
-/// Information for one frame in the browsing context.
-#[deriving(Encodable)]
-pub struct Frame {
-    /// The document for this frame.
-    pub document: JS<Document>,
-    /// The window object for this frame.
-    pub window: JS<Window>,
-}
-
-/// Encapsulation of the javascript information associated with each frame.
-#[deriving(Encodable)]
-pub struct JSPageInfo {
-    /// Global static data related to the DOM.
-    pub dom_static: GlobalStaticData,
-    /// The JavaScript context.
-    pub js_context: Untraceable<Rc<Cx>>,
-}
-
 struct StackRootTLS;
 
 impl StackRootTLS {