Initial spec-incompliant implementation of default click action for anchor elements.

This is cherry-picked from https://github.com/mozilla/servo/pull/1688:

  * Initial spec-incompliant implementation of default click action for anchor elements.
  * Add documentation; gut the new document URL loading method
    and move it all into the new Window method.
  * Add test for default event prevention.

Original developer: Josh Matthews <josh@joshmatthews.net>

src/components/script/dom/document.rs

@@ -83,6 +83,7 @@ pub trait DocumentHelpers {
     fn wait_until_safe_to_modify_dom(&self);
     fn unregister_named_element(&mut self, to_unregister: &JSRef<Element>, id: DOMString);
     fn register_named_element(&mut self, element: &JSRef<Element>, id: DOMString);
+    fn load_anchor_href(&self, href: DOMString);
 }
 
 impl<'a> DocumentHelpers for JSRef<'a, Document> {
@@ -176,6 +177,11 @@ impl<'a> DocumentHelpers for JSRef<'a, Document> {
         elements.push_unrooted(element);
         self.idmap.insert(id, elements);
     }
+
+    fn load_anchor_href(&self, href: DOMString) {
+        let mut window = self.window.root();
+        window.load_url(href);
+    }
 }
 
 impl Document {

src/components/script/dom/eventdispatcher.rs

@@ -4,10 +4,11 @@
 
 use dom::bindings::callback::ReportExceptions;
 use dom::bindings::codegen::InheritTypes::{EventTargetCast, NodeCast, NodeDerived};
-use dom::bindings::js::{JSRef, OptionalSettable, Root};
+use dom::bindings::js::{JSRef, OptionalSettable, OptionalRootable, Root};
 use dom::eventtarget::{Capturing, Bubbling, EventTarget};
 use dom::event::{Event, PhaseAtTarget, PhaseNone, PhaseBubbling, PhaseCapturing, EventMethods};
 use dom::node::{Node, NodeHelpers};
+use dom::virtualmethods::vtable_for;
 
 // See http://dom.spec.whatwg.org/#concept-event-dispatch for the full dispatch algorithm
 pub fn dispatch_event<'a, 'b>(target: &JSRef<'a, EventTarget>,
@@ -115,6 +116,22 @@ pub fn dispatch_event<'a, 'b>(target: &JSRef<'a, EventTarget>,
         }
     }
 
+    /* default action */
+    let target = event.GetTarget().root();
+    match target {
+        Some(mut target) => {
+            let node: Option<&mut JSRef<Node>> = NodeCast::to_mut_ref(&mut *target);
+            match node {
+                Some(node) =>{
+                    let vtable = vtable_for(node);
+                    vtable.handle_event(event);
+                }
+                None => {}
+            }
+        }
+        None => {}
+    }
+
     // Root ordering restrictions mean we need to unroot the chain entries
     // in the same order they were rooted.
     while chain.len() > 0 {

src/components/script/dom/htmlanchorelement.rs

@@ -4,13 +4,18 @@
 
 use dom::bindings::codegen::BindingDeclarations::HTMLAnchorElementBinding;
 use dom::bindings::codegen::InheritTypes::HTMLAnchorElementDerived;
-use dom::bindings::js::{JSRef, Temporary};
+use dom::bindings::codegen::InheritTypes::{ElementCast, HTMLElementCast, NodeCast};
+use dom::bindings::js::{JSRef, Temporary, OptionalRootable};
 use dom::bindings::error::ErrorResult;
-use dom::document::Document;
-use dom::element::HTMLAnchorElementTypeId;
+use dom::document::{Document, DocumentHelpers};
+use dom::attr::AttrMethods;
+use dom::element::{Element, AttributeHandlers, HTMLAnchorElementTypeId};
+use dom::event::{Event, EventMethods};
 use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{Node, ElementNodeTypeId};
+use dom::node::{Node, NodeHelpers, ElementNodeTypeId};
+use dom::virtualmethods::VirtualMethods;
+use servo_util::namespace::Null;
 use servo_util::str::DOMString;
 
 #[deriving(Encodable)]
@@ -171,3 +176,43 @@ impl<'a> HTMLAnchorElementMethods for JSRef<'a, HTMLAnchorElement> {
         Ok(())
     }
 }
+
+trait PrivateHTMLAnchorElementHelpers {
+    fn handle_event_impl(&self, event: &JSRef<Event>);
+}
+
+impl<'a> PrivateHTMLAnchorElementHelpers for JSRef<'a, HTMLAnchorElement> {
+    fn handle_event_impl(&self, event: &JSRef<Event>) {
+        if "click" == event.Type() && !event.DefaultPrevented() {
+            let element: &JSRef<Element> = ElementCast::from_ref(self);
+            let attr = element.get_attribute(Null, "href").root();
+            match attr {
+                Some(ref href) => {
+                    let value = href.Value();
+                    debug!("clicked on link to {:s}", value);
+                    let node: &JSRef<Node> = NodeCast::from_ref(self);
+                    let mut doc = node.owner_doc().root();
+                    doc.load_anchor_href(value);
+                }
+                None => ()
+            }
+        }
+    }
+}
+
+impl<'a> VirtualMethods for JSRef<'a, HTMLAnchorElement> {
+    fn super_type<'a>(&'a mut self) -> Option<&'a mut VirtualMethods:> {
+        let htmlelement: &mut JSRef<HTMLElement> = HTMLElementCast::from_mut_ref(self);
+        Some(htmlelement as &mut VirtualMethods:)
+    }
+
+    fn handle_event(&mut self, event: &JSRef<Event>) {
+        match self.super_type() {
+            Some(s) => {
+                s.handle_event(event);
+            }
+            None => {}
+        }
+        self.handle_event_impl(event);
+    }
+}

src/components/script/dom/virtualmethods.rs

@@ -3,6 +3,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::InheritTypes::ElementCast;
+use dom::bindings::codegen::InheritTypes::HTMLAnchorElementCast;
 use dom::bindings::codegen::InheritTypes::HTMLElementCast;
 use dom::bindings::codegen::InheritTypes::HTMLIFrameElementCast;
 use dom::bindings::codegen::InheritTypes::HTMLImageElementCast;
@@ -10,8 +11,10 @@ use dom::bindings::codegen::InheritTypes::HTMLObjectElementCast;
 use dom::bindings::codegen::InheritTypes::HTMLStyleElementCast;
 use dom::bindings::js::JSRef;
 use dom::element::Element;
-use dom::element::{ElementTypeId, HTMLImageElementTypeId};
+use dom::element::{ElementTypeId, HTMLAnchorElementTypeId, HTMLImageElementTypeId};
 use dom::element::{HTMLIFrameElementTypeId, HTMLObjectElementTypeId, HTMLStyleElementTypeId};
+use dom::event::Event;
+use dom::htmlanchorelement::HTMLAnchorElement;
 use dom::htmlelement::HTMLElement;
 use dom::htmliframeelement::HTMLIFrameElement;
 use dom::htmlimageelement::HTMLImageElement;
@@ -68,6 +71,16 @@ pub trait VirtualMethods {
             _ => (),
         }
     }
+
+    /// Called during event dispatch after the bubbling phase completes.
+    fn handle_event(&mut self, event: &JSRef<Event>) {
+        match self.super_type() {
+            Some(s) => {
+                s.handle_event(event);
+            }
+            _ => (),
+        }
+    }
 }
 
 /// Obtain a VirtualMethods instance for a given Node-derived object. Any
@@ -76,6 +89,10 @@ pub trait VirtualMethods {
 /// interrupted.
 pub fn vtable_for<'a>(node: &'a mut JSRef<Node>) -> &'a mut VirtualMethods: {
     match node.type_id() {
+        ElementNodeTypeId(HTMLAnchorElementTypeId) => {
+            let element: &mut JSRef<HTMLAnchorElement> = HTMLAnchorElementCast::to_mut_ref(node).unwrap();
+            element as &mut VirtualMethods:
+        }
         ElementNodeTypeId(HTMLImageElementTypeId) => {
             let element: &mut JSRef<HTMLImageElement> = HTMLImageElementCast::to_mut_ref(node).unwrap();
             element as &mut VirtualMethods:

src/components/script/dom/window.rs

@@ -16,11 +16,12 @@ use dom::navigator::Navigator;
 use dom::performance::Performance;
 
 use layout_interface::{ReflowForDisplay, DocumentDamageLevel};
-use script_task::{ExitWindowMsg, FireTimerMsg, Page, ScriptChan};
+use script_task::{ExitWindowMsg, FireTimerMsg, Page, ScriptChan, TriggerLoadMsg, TriggerFragmentMsg};
 use servo_msg::compositor_msg::ScriptListener;
 use servo_net::image_cache_task::ImageCacheTask;
 use servo_util::str::DOMString;
 use servo_util::task::{spawn_named};
+use servo_util::url::parse_url;
 
 use js::jsapi::JSContext;
 use js::jsapi::{JS_GC, JS_GetRuntime};
@@ -292,6 +293,7 @@ pub trait WindowHelpers {
     fn damage_and_reflow(&self, damage: DocumentDamageLevel);
     fn wait_until_safe_to_modify_dom(&self);
     fn init_browser_context(&mut self, doc: &JSRef<Document>);
+    fn load_url(&self, href: DOMString);
 }
 
 trait PrivateWindowHelpers {
@@ -316,6 +318,19 @@ impl<'a> WindowHelpers for JSRef<'a, Window> {
     fn init_browser_context(&mut self, doc: &JSRef<Document>) {
         self.browser_context = Some(BrowserContext::new(doc));
     }
+
+    /// Commence a new URL load which will either replace this window or scroll to a fragment.
+    fn load_url(&self, href: DOMString) {
+        let base_url = Some(self.page().get_url());
+        debug!("current page url is {:?}", base_url);
+        let url = parse_url(href, base_url);
+        let ScriptChan(ref script_chan) = self.script_chan;
+        if href.starts_with("#") {
+            script_chan.send(TriggerFragmentMsg(self.page.id, url));
+        } else {
+            script_chan.send(TriggerLoadMsg(self.page.id, url));
+        }
+    }
 }
 
 impl<'a> PrivateWindowHelpers for JSRef<'a, Window> {