add pipeline.rs, modularized pipelines communicating with constellation

9 files changed, 116 insertions, 129 deletions

diff --git a/src/components/script/dom/bindings/element.rs b/src/components/script/dom/bindings/element.rs
index 9a34f7c5dc6..b79daf75db7 100644
--- a/src/components/script/dom/bindings/element.rs
+++ b/src/components/script/dom/bindings/element.rs
@@ -16,6 +16,7 @@ use std::cast;
 use std::i32;
 use std::libc;
 use std::libc::c_uint;
+use std::comm;
 use std::ptr;
 use std::ptr::null;
 use std::result;
@@ -229,13 +230,9 @@ extern fn HTMLImageElement_getWidth(cx: *JSContext, _argc: c_uint, vp: *mut JSVa
         let width = match node.type_id() {
             ElementNodeTypeId(HTMLImageElementTypeId) => {
                 let script_context = task_from_context(cx);
-                match (*script_context).query_layout(ContentBoxQuery(node)) {
-                    Ok(rect) => {
-                        match rect {
-                            ContentBoxResponse(rect) => rect.size.width.to_px(),
-                            _ => fail!(~"unexpected layout reply")
-                        }
-                    }
+                let (port, chan) = comm::stream();
+                match (*script_context).query_layout(ContentBoxQuery(node, chan), port) {
+                    Ok(ContentBoxResponse(rect)) => rect.size.width.to_px(),
                     Err(()) => 0
                 }
                 // TODO: if nothing is being rendered(?), return zero dimensions
diff --git a/src/components/script/dom/bindings/proxyhandler.rs b/src/components/script/dom/bindings/proxyhandler.rs
index 2780a969eb2..cbbc4f1525d 100644
--- a/src/components/script/dom/bindings/proxyhandler.rs
+++ b/src/components/script/dom/bindings/proxyhandler.rs
@@ -71,7 +71,7 @@ pub fn _obj_toString(cx: *JSContext, className: *libc::c_char) -> *JSString {
         return ptr::null();
     }
 
-    let result = ~"[object " + name + ~"]";
+    let result = ~"[object " + name + "]";
     for result.iter().enumerate().advance |(i, c)| {
       *chars.offset(i) = c as jschar;
     }
@@ -86,4 +86,4 @@ pub fn _obj_toString(cx: *JSContext, className: *libc::c_char) -> *JSString {
 
 pub fn GetExpandoObject(_proxy: *JSObject) -> *JSObject {
     ptr::null()
-}
\ No newline at end of file
+}
diff --git a/src/components/script/dom/bindings/utils.rs b/src/components/script/dom/bindings/utils.rs
index 9d3105fefca..5a42e109268 100644
--- a/src/components/script/dom/bindings/utils.rs
+++ b/src/components/script/dom/bindings/utils.rs
@@ -21,12 +21,12 @@ use js::glue::{PROPERTY_STUB, STRICT_PROPERTY_STUB, ENUMERATE_STUB, CONVERT_STUB
 use js::jsapi::{JS_AlreadyHasOwnProperty, JS_NewObject, JS_NewFunction};
 use js::jsapi::{JS_DefineProperties, JS_WrapValue, JS_ForwardGetPropertyTo};
 use js::jsapi::{JS_EncodeString, JS_free, JS_GetStringCharsAndLength};
-use js::jsapi::{JS_GetClass, JS_GetPrototype, JS_LinkConstructorAndPrototype};
+use js::jsapi::{JS_GetClass, JS_LinkConstructorAndPrototype};
 use js::jsapi::{JS_GetFunctionPrototype, JS_InternString, JS_GetFunctionObject};
 use js::jsapi::{JS_HasPropertyById, JS_GetPrototype, JS_GetGlobalForObject};
 use js::jsapi::{JS_NewStringCopyN, JS_DefineFunctions, JS_DefineProperty};
 use js::jsapi::{JS_ValueToString, JS_GetReservedSlot, JS_SetReservedSlot};
-use js::jsapi::{JSContext, JSVal, JSObject, JSBool, jsid, JSClass, JSNative};
+use js::jsapi::{JSContext, JSObject, JSBool, jsid, JSClass, JSNative};
 use js::jsapi::{JSFunctionSpec, JSPropertySpec, JSVal, JSPropertyDescriptor};
 use js::jsfriendapi::bindgen::JS_NewObjectWithUniqueType;
 use js::rust::Compartment;
@@ -83,7 +83,7 @@ extern fn InterfaceObjectToString(cx: *JSContext, _argc: uint, vp: *mut JSVal) -
     }
 
     let name = jsval_to_str(cx, *v).get();
-    let retval = str(~"function " + name + ~"() {\n    [native code]\n}");
+    let retval = str(~"function " + name + "() {\n    [native code]\n}");
     *vp = domstring_to_jsval(cx, &retval);
     return 1;
   }
diff --git a/src/components/script/dom/element.rs b/src/components/script/dom/element.rs
index e707a95ebb9..2595a68657d 100644
--- a/src/components/script/dom/element.rs
+++ b/src/components/script/dom/element.rs
@@ -12,6 +12,7 @@ use layout_interface::{ContentBoxQuery, ContentBoxResponse, ContentBoxesQuery};
 use layout_interface::{ContentBoxesResponse};
 
 use std::cell::Cell;
+use std::comm;
 use std::uint;
 use std::str::eq_slice;
 use extra::net::url::Url;
@@ -165,20 +166,19 @@ impl<'self> Element {
                     Some(win) => {
                         let node = self.parent.abstract.get();
                         assert!(node.is_element());
-                        let script_context = unsafe {
-                            &mut *win.script_context
+                        let script_task = unsafe {
+                            &mut *win.script_task
                         };
-                        match script_context.query_layout(ContentBoxesQuery(node)) {
-                            Ok(rects) => match rects {
-                                ContentBoxesResponse(rects) =>
-                                    do rects.map |r| {
-                                        ClientRect::new(
-                                             r.origin.y.to_f32(),
-                                             (r.origin.y + r.size.height).to_f32(),
-                                             r.origin.x.to_f32(),
-                                             (r.origin.x + r.size.width).to_f32())
-                                    },
-                                _ => fail!(~"unexpected layout reply")
+                        let (port, chan) = comm::stream();
+                        match script_task.query_layout(ContentBoxesQuery(node, chan), port) {
+                            Ok(ContentBoxesResponse(rects)) => {
+                                do rects.map |r| {
+                                    ClientRect::new(
+                                         r.origin.y.to_f32(),
+                                         (r.origin.y + r.size.height).to_f32(),
+                                         r.origin.x.to_f32(),
+                                         (r.origin.x + r.size.width).to_f32())
+                                }
                             },
                             Err(()) => {
                                 debug!("layout query error");
@@ -207,16 +207,15 @@ impl<'self> Element {
                     Some(win) => {
                         let node = self.parent.abstract.get();
                         assert!(node.is_element());
-                        let script_context = unsafe { &mut *win.script_context };
-                        match script_context.query_layout(ContentBoxQuery(node)) {
-                            Ok(rect) => match rect {
-                                ContentBoxResponse(rect) =>
-                                    Some(ClientRect::new(
-                                             rect.origin.y.to_f32(),
-                                             (rect.origin.y + rect.size.height).to_f32(),
-                                             rect.origin.x.to_f32(),
-                                             (rect.origin.x + rect.size.width).to_f32())),
-                                _ => fail!(~"unexpected layout result")
+                        let script_task = unsafe { &mut *win.script_task };
+                        let (port, chan) = comm::stream();
+                        match script_task.query_layout(ContentBoxQuery(node, chan), port) {
+                            Ok(ContentBoxResponse(rect)) => {
+                                Some(ClientRect::new(
+                                         rect.origin.y.to_f32(),
+                                         (rect.origin.y + rect.size.height).to_f32(),
+                                         rect.origin.x.to_f32(),
+                                         (rect.origin.x + rect.size.width).to_f32()))
                             },
                             Err(()) => {
                                 debug!("error querying layout");
diff --git a/src/components/script/dom/event.rs b/src/components/script/dom/event.rs
index 047b734e6b4..6b4be15b701 100644
--- a/src/components/script/dom/event.rs
+++ b/src/components/script/dom/event.rs
@@ -9,8 +9,6 @@ use dom::bindings::utils::{DOMString, ErrorResult, WrapperCache};
 
 use geom::point::Point2D;
 
-use std::comm;
-
 pub enum Event {
     ResizeEvent(uint, uint), 
     ReflowEvent,
diff --git a/src/components/script/dom/window.rs b/src/components/script/dom/window.rs
index 5fb07c66f07..41f99eaa9e9 100644
--- a/src/components/script/dom/window.rs
+++ b/src/components/script/dom/window.rs
@@ -6,7 +6,7 @@ use dom::bindings::utils::WrapperCache;
 use dom::bindings::window;
 
 use layout_interface::ReflowForScriptQuery;
-use script_task::{ExitMsg, FireTimerMsg, ScriptChan, ScriptContext};
+use script_task::{ExitMsg, FireTimerMsg, ScriptChan, ScriptTask};
 
 use std::comm;
 use std::comm::Chan;
@@ -29,7 +29,7 @@ pub enum TimerControlMsg {
 pub struct Window {
     timer_chan: Chan<TimerControlMsg>,
     script_chan: ScriptChan,
-    script_context: *mut ScriptContext,
+    script_task: *mut ScriptTask,
     wrapper: WrapperCache
 }
 
@@ -89,11 +89,11 @@ impl Window {
 
     pub fn content_changed(&self) {
         unsafe {
-            (*self.script_context).reflow_all(ReflowForScriptQuery)
+            (*self.script_task).reflow_all(ReflowForScriptQuery)
         }
     }
 
-    pub fn new(script_chan: ScriptChan, script_context: *mut ScriptContext)
+    pub fn new(script_chan: ScriptChan, script_task: *mut ScriptTask)
                -> @mut Window {
         let script_chan_clone = script_chan.clone();
         let win = @mut Window {
@@ -112,11 +112,11 @@ impl Window {
                 }
                 timer_chan
             },
-            script_context: script_context,
+            script_task: script_task,
         };
 
         unsafe {
-            let compartment = (*script_context).js_compartment;
+            let compartment = (*script_task).js_compartment;
             window::create(compartment, win);
         }
         win
diff --git a/src/components/script/html/hubbub_html_parser.rs b/src/components/script/html/hubbub_html_parser.rs
index 6309e488d7e..9540fcc87d4 100644
--- a/src/components/script/html/hubbub_html_parser.rs
+++ b/src/components/script/html/hubbub_html_parser.rs
@@ -303,9 +303,9 @@ pub fn parse_html(url: Url,
                 // Handle CSS style sheets from <link> elements
                 ElementNodeTypeId(HTMLLinkElementTypeId) => {
                     do node.with_imm_element |element| {
-                        match (element.get_attr(~"rel"), element.get_attr(~"href")) {
+                        match (element.get_attr("rel"), element.get_attr("href")) {
                             (Some(rel), Some(href)) => {
-                                if rel == ~"stylesheet" {
+                                if rel == "stylesheet" {
                                     debug!("found CSS stylesheet: %s", href);
                                     let url = make_url(href.to_str(), Some(url2.clone()));
                                     css_chan2.send(CSSTaskNewFile(UrlProvenance(url)));
@@ -317,7 +317,7 @@ pub fn parse_html(url: Url,
                 },
                 ElementNodeTypeId(HTMLImageElementTypeId) => {
                     do node.with_mut_image_element |image_element| {
-                        let src_opt = image_element.parent.get_attr(~"src").map(|x| x.to_str());
+                        let src_opt = image_element.parent.get_attr("src").map(|x| x.to_str());
                         match src_opt {
                             None => {}
                             Some(src) => {
@@ -401,7 +401,7 @@ pub fn parse_html(url: Url,
                 unsafe {
                     let script: AbstractNode<ScriptView> = NodeWrapping::from_hubbub_node(script);
                     do script.with_imm_element |script| {
-                        match script.get_attr(~"src") {
+                        match script.get_attr("src") {
                             Some(src) => {
                                 debug!("found script: %s", src);
                                 let new_url = make_url(src.to_str(), Some(url.clone()));
diff --git a/src/components/script/layout_interface.rs b/src/components/script/layout_interface.rs
index 3a1531b83e6..766c728067b 100644
--- a/src/components/script/layout_interface.rs
+++ b/src/components/script/layout_interface.rs
@@ -30,7 +30,7 @@ pub enum Msg {
     /// Performs a synchronous layout request.
     ///
     /// FIXME(pcwalton): As noted below, this isn't very type safe.
-    QueryMsg(LayoutQuery, Chan<Result<LayoutResponse,()>>),
+    QueryMsg(LayoutQuery),
 
     /// Routes a message (usually from the compositor) to the appropriate script task
     RouteScriptMsg(ScriptMsg),
@@ -42,25 +42,16 @@ pub enum Msg {
 /// Synchronous messages that script can send to layout.
 pub enum LayoutQuery {
     /// Requests the dimensions of the content box, as in the `getBoundingClientRect()` call.
-    ContentBoxQuery(AbstractNode<ScriptView>),
+    ContentBoxQuery(AbstractNode<ScriptView>, Chan<Result<ContentBoxResponse, ()>>),
     /// Requests the dimensions of all the content boxes, as in the `getClientRects()` call.
-    ContentBoxesQuery(AbstractNode<ScriptView>),
+    ContentBoxesQuery(AbstractNode<ScriptView>, Chan<Result<ContentBoxesResponse, ()>>),
     /// Requests the node containing the point of interest
-    HitTestQuery(AbstractNode<ScriptView>, Point2D<f32>),
+    HitTestQuery(AbstractNode<ScriptView>, Point2D<f32>, Chan<Result<HitTestResponse, ()>>),
 }
 
-/// The reply of a synchronous message from script to layout.
-///
-/// FIXME(pcwalton): This isn't very type safe. Maybe `LayoutQuery` objects should include
-/// response channels?
-pub enum LayoutResponse {
-    /// A response to the `ContentBoxQuery` message.
-    ContentBoxResponse(Rect<Au>),
-    /// A response to the `ContentBoxesQuery` message.
-    ContentBoxesResponse(~[Rect<Au>]),
-    /// A response to the `HitTestQuery` message.
-    HitTestResponse(AbstractNode<LayoutView>),
-}
+pub struct ContentBoxResponse(Rect<Au>);
+pub struct ContentBoxesResponse(~[Rect<Au>]);
+pub struct HitTestResponse(AbstractNode<LayoutView>);
 
 /// Determines which part of the 
 pub enum DocumentDamageLevel {
diff --git a/src/components/script/script_task.rs b/src/components/script/script_task.rs
index 7ef0b0035e1..ce89ef5efd7 100644
--- a/src/components/script/script_task.rs
+++ b/src/components/script/script_task.rs
@@ -5,19 +5,21 @@
 /// The script task is the task that owns the DOM in memory, runs JavaScript, and spawns parsing
 /// and layout tasks.
 
-use servo_msg::compositor::{ReadyState, Loading, PerformingLayout, FinishedLoading};
+use servo_msg::compositor::{ScriptListener, Loading, PerformingLayout};
+use servo_msg::compositor::FinishedLoading;
 use dom::bindings::utils::GlobalStaticData;
 use dom::document::Document;
 use dom::element::Element;
 use dom::event::{Event, ResizeEvent, ReflowEvent, ClickEvent, MouseDownEvent, MouseUpEvent};
 use dom::node::{AbstractNode, ScriptView, define_bindings};
 use dom::window::Window;
-use layout_interface::{AddStylesheetMsg, DocumentDamage, DocumentDamageLevel, HitTestQuery};
-use layout_interface::{HitTestResponse, LayoutQuery, LayoutResponse, LayoutChan};
-use layout_interface::{MatchSelectorsDocumentDamage, QueryMsg, Reflow, ReflowDocumentDamage};
-use layout_interface::{ReflowForDisplay, ReflowForScriptQuery, ReflowGoal, ReflowMsg};
+use layout_interface::{AddStylesheetMsg, DocumentDamage};
+use layout_interface::{DocumentDamageLevel, HitTestQuery, HitTestResponse, LayoutQuery};
+use layout_interface::{LayoutChan, MatchSelectorsDocumentDamage, QueryMsg, Reflow};
+use layout_interface::{ReflowDocumentDamage, ReflowForDisplay, ReflowForScriptQuery, ReflowGoal};
+use layout_interface::ReflowMsg;
 use layout_interface;
-use servo_msg::engine::{EngineChan, LoadUrlMsg};
+use servo_msg::engine::{EngineChan, LoadUrlMsg, RendererReadyMsg};
 
 use std::cast::transmute;
 use std::cell::Cell;
@@ -91,7 +93,9 @@ pub struct Frame {
 /// frames.
 ///
 /// FIXME: Rename to `Page`, following WebKit?
-pub struct ScriptContext {
+pub struct ScriptTask {
+    /// A unique identifier to the script's pipeline
+    id: uint,
     /// A handle to the layout task.
     layout_chan: LayoutChan,
     /// A handle to the image cache task.
@@ -110,8 +114,8 @@ pub struct ScriptContext {
 
     /// For communicating load url messages to the engine
     engine_chan: EngineChan,
-    /// For communicating loading messages to the compositor
-    compositor_task: ~fn(ReadyState),
+    /// For permission to communicate ready state messages to the compositor
+    compositor: @ScriptListener,
 
     /// The JavaScript runtime.
     js_runtime: js::rust::rt,
@@ -134,26 +138,26 @@ pub struct ScriptContext {
     damage: Option<DocumentDamage>,
 }
 
-fn global_script_context_key(_: @ScriptContext) {}
+fn global_script_context_key(_: @ScriptTask) {}
 
 /// Returns this task's script context singleton.
-pub fn global_script_context() -> @ScriptContext {
+pub fn global_script_context() -> @ScriptTask {
     unsafe {
         local_data::local_data_get(global_script_context_key).get()
     }
 }
 
-/// Returns the script context from the JS Context.
+/// Returns the script task from the JS Context.
 ///
 /// FIXME: Rename to `script_context_from_js_context`.
-pub fn task_from_context(js_context: *JSContext) -> *mut ScriptContext {
+pub fn task_from_context(js_context: *JSContext) -> *mut ScriptTask {
     unsafe {
-        JS_GetContextPrivate(js_context) as *mut ScriptContext
+        JS_GetContextPrivate(js_context) as *mut ScriptTask
     }
 }
 
 #[unsafe_destructor]
-impl Drop for ScriptContext {
+impl Drop for ScriptTask {
     fn finalize(&self) {
         unsafe {
             let _ = local_data::local_data_pop(global_script_context_key);
@@ -161,16 +165,17 @@ impl Drop for ScriptContext {
     }
 }
 
-impl ScriptContext {
-    /// Creates a new script context.
-    pub fn new(layout_chan: LayoutChan,
+impl ScriptTask {
+    /// Creates a new script task.
+    pub fn new(id: uint,
+               compositor: @ScriptListener,
+               layout_chan: LayoutChan,
                script_port: Port<ScriptMsg>,
                script_chan: ScriptChan,
                engine_chan: EngineChan,
-               compositor_task: ~fn(ReadyState),
                resource_task: ResourceTask,
                img_cache_task: ImageCacheTask)
-               -> @mut ScriptContext {
+               -> @mut ScriptTask {
         let js_runtime = js::rust::rt();
         let js_context = js_runtime.cx();
 
@@ -182,7 +187,10 @@ impl ScriptContext {
               Err(()) => fail!("Failed to create a compartment"),
         };
 
-        let script_context = @mut ScriptContext {
+        let script_task = @mut ScriptTask {
+            id: id,
+            compositor: compositor,
+
             layout_chan: layout_chan,
             image_cache_task: img_cache_task,
             resource_task: resource_task,
@@ -192,7 +200,6 @@ impl ScriptContext {
             script_chan: script_chan,
 
             engine_chan: engine_chan,
-            compositor_task: compositor_task,
 
             js_runtime: js_runtime,
             js_context: js_context,
@@ -207,17 +214,17 @@ impl ScriptContext {
             damage: None,
         };
         // Indirection for Rust Issue #6248, dynamic freeze scope artifically extended
-        let script_context_ptr = {
-            let borrowed_ctx= &mut *script_context;
-            borrowed_ctx as *mut ScriptContext
+        let script_task_ptr = {
+            let borrowed_ctx= &mut *script_task;
+            borrowed_ctx as *mut ScriptTask
         };
 
         unsafe {
-            js_context.set_cx_private(script_context_ptr as *());
-            local_data::local_data_set(global_script_context_key, transmute(script_context))
+            js_context.set_cx_private(script_task_ptr as *());
+            local_data::local_data_set(global_script_context_key, transmute(script_task))
         }
 
-        script_context
+        script_task
     }
 
     /// Starts the script task. After calling this method, the script task will loop receiving
@@ -228,27 +235,29 @@ impl ScriptContext {
         }
     }
 
-    pub fn create_script_context(layout_chan: LayoutChan,
-                                 script_port: Port<ScriptMsg>,
-                                 script_chan: ScriptChan,
-                                 engine_chan: EngineChan,
-                                 compositor_task: ~fn(ReadyState),
-                                 resource_task: ResourceTask,
-                                 image_cache_task: ImageCacheTask) {
+    pub fn create<C: ScriptListener + Owned>(id: uint,
+                  compositor: C,
+                  layout_chan: LayoutChan,
+                  script_port: Port<ScriptMsg>,
+                  script_chan: ScriptChan,
+                  engine_chan: EngineChan,
+                  resource_task: ResourceTask,
+                  image_cache_task: ImageCacheTask) {
+        let compositor = Cell::new(compositor);
         let script_port = Cell::new(script_port);
-        let compositor_task = Cell::new(compositor_task);
         // FIXME: rust#6399
         let mut the_task = task();
         the_task.sched_mode(SingleThreaded);
-        do the_task.spawn {
-            let script_context = ScriptContext::new(layout_chan.clone(),
-                                                    script_port.take(),
-                                                    script_chan.clone(),
-                                                    engine_chan.clone(),
-                                                    compositor_task.take(),
-                                                    resource_task.clone(),
-                                                    image_cache_task.clone());
-            script_context.start();
+        do spawn {
+            let script_task = ScriptTask::new(id,
+                                              @compositor.take() as @ScriptListener,
+                                              layout_chan.clone(),
+                                              script_port.take(),
+                                              script_chan.clone(),
+                                              engine_chan.clone(),
+                                              resource_task.clone(),
+                                              image_cache_task.clone());
+            script_task.start();
         }
     }
 
@@ -324,7 +333,8 @@ impl ScriptContext {
     /// Handles a notification that reflow completed.
     fn handle_reflow_complete_msg(&mut self) {
         self.layout_join_port = None;
-        self.set_ready_state(FinishedLoading)
+        self.engine_chan.send(RendererReadyMsg(self.id));
+        self.compositor.set_ready_state(FinishedLoading);
     }
 
     /// Handles a request to exit the script task and shut down layout.
@@ -337,12 +347,6 @@ impl ScriptContext {
         self.layout_chan.send(layout_interface::ExitMsg)
     }
 
-    // tells the compositor when loading starts and finishes
-    // FIXME ~compositor_interface doesn't work right now, which is why this is necessary
-    fn set_ready_state(&self, msg: ReadyState) {
-        (self.compositor_task)(msg);
-    }
-
     /// The entry point to document loading. Defines bindings, sets up the window and document
     /// objects, parses HTML and CSS, and kicks off initial layout.
     fn load(&mut self, url: Url) {
@@ -354,7 +358,7 @@ impl ScriptContext {
             self.bindings_initialized = true
         }
 
-        self.set_ready_state(Loading);
+        self.compositor.set_ready_state(Loading);
         // Parse HTML.
         //
         // Note: We can parse the next document in parallel with any previous documents.
@@ -446,7 +450,7 @@ impl ScriptContext {
         self.join_layout();
 
         // Tell the user that we're performing layout.
-        self.set_ready_state(PerformingLayout);
+        self.compositor.set_ready_state(PerformingLayout);
 
         // Layout will let us know when it's done.
         let (join_port, join_chan) = comm::stream();
@@ -478,7 +482,7 @@ impl ScriptContext {
     /// FIXME: This should basically never be used.
     pub fn reflow_all(&mut self, goal: ReflowGoal) {
         for self.root_frame.iter().advance |root_frame| {
-            ScriptContext::damage(&mut self.damage,
+            ScriptTask::damage(&mut self.damage,
                                   root_frame.document.root,
                                   MatchSelectorsDocumentDamage)
         }
@@ -487,12 +491,10 @@ impl ScriptContext {
     }
 
     /// Sends the given query to layout.
-    pub fn query_layout(&mut self, query: LayoutQuery) -> Result<LayoutResponse,()> {
-         self.join_layout();
-
-         let (response_port, response_chan) = comm::stream();
-         self.layout_chan.send(QueryMsg(query, response_chan));
-         response_port.recv()
+    pub fn query_layout<T: Owned>(&mut self, query: LayoutQuery, response_port: Port<Result<T, ()>>) -> Result<T,()> {
+        self.join_layout();
+        self.layout_chan.send(QueryMsg(query));
+        response_port.recv()
     }
 
     /// Adds the given damage.
@@ -526,7 +528,7 @@ impl ScriptContext {
                 self.window_size = Size2D(new_width, new_height);
 
                 for self.root_frame.iter().advance |root_frame| {
-                    ScriptContext::damage(&mut self.damage,
+                    ScriptTask::damage(&mut self.damage,
                                           root_frame.document.root,
                                           ReflowDocumentDamage);
                 }
@@ -541,7 +543,7 @@ impl ScriptContext {
                 debug!("script got reflow event");
 
                 for self.root_frame.iter().advance |root_frame| {
-                    ScriptContext::damage(&mut self.damage,
+                    ScriptTask::damage(&mut self.damage,
                                           root_frame.document.root,
                                           MatchSelectorsDocumentDamage);
                 }
@@ -557,7 +559,8 @@ impl ScriptContext {
                     Some(ref frame) => frame.document.root,
                     None => fail!("root frame is None")
                 };
-                match self.query_layout(HitTestQuery(root, point)) {
+                let (port, chan) = comm::stream();
+                match self.query_layout(HitTestQuery(root, point, chan), port) {
                     Ok(node) => match node {
                         HitTestResponse(node) => {
                             debug!("clicked on %?", node.debug_str());
@@ -580,7 +583,6 @@ impl ScriptContext {
                                 }
                             }
                         }
-                        _ => fail!(~"unexpected layout reply")
                     },
                     Err(()) => {
                         debug!(fmt!("layout query error"));
@@ -594,7 +596,7 @@ impl ScriptContext {
 
     priv fn load_url_from_element(&self, element: &Element) {
         // if the node's element is "a," load url from href attr
-        for element.attrs.each |attr| {
+        for element.attrs.iter().advance |attr| {
             if attr.name == ~"href" {
                 debug!("clicked on link to %?", attr.value); 
                 let current_url = match self.root_frame {