Introduce VirtualMethods::attribute_mutated()

This replaces before_remove_attr(), after_remove_attr() and after_set_attr().
The virtual method takes the mutated attribute and an AttributeMutation value
to disambiguate between "attribute is changed", "attribute is added" and
"attribute is removed".

In the case of "attribute is changed", the mutation value contains a reference
to the old value of the mutated attribute, which is used to unregister outdated
named elements when the "id" attribute is changed on an element.

This greatly simplifies the handling of attributes, which in many cases don't
have any specific behaviour whether they are removed or changed or added. It
also fixes a few bugs where things were put in before_remove_attr() instead of
after_remove_attr() (e.g. when removing an href attribute from a base element).

A few helper functions in Element were also renamed and made private.

1 files changed, 6 insertions, 18 deletions

diff --git a/components/script/dom/htmlbaseelement.rs b/components/script/dom/htmlbaseelement.rs
index 0a6e0ed8d0a..62db191aa05 100644
--- a/components/script/dom/htmlbaseelement.rs
+++ b/components/script/dom/htmlbaseelement.rs
@@ -9,7 +9,7 @@ use dom::bindings::codegen::InheritTypes::HTMLBaseElementDerived;
 use dom::bindings::codegen::InheritTypes::HTMLElementCast;
 use dom::bindings::js::Root;
 use dom::document::Document;
-use dom::element::ElementTypeId;
+use dom::element::{AttributeMutation, ElementTypeId};
 use dom::eventtarget::{EventTarget, EventTargetTypeId};
 use dom::htmlelement::{HTMLElement, HTMLElementTypeId};
 use dom::node::{Node, NodeTypeId, document_from_node};
@@ -56,15 +56,6 @@ impl HTMLBaseElement {
         parsed.unwrap_or(base)
     }
 
-    /// Update the cached base element in response to adding or removing an
-    /// attribute.
-    pub fn add_remove_attr(&self, attr: &Attr) {
-        if *attr.local_name() == atom!("href") {
-            let document = document_from_node(self);
-            document.refresh_base_element();
-        }
-    }
-
     /// Update the cached base element in response to binding or unbinding from
     /// a tree.
     pub fn bind_unbind(&self, tree_in_doc: bool) {
@@ -84,14 +75,11 @@ impl VirtualMethods for HTMLBaseElement {
         Some(HTMLElementCast::from_ref(self) as &VirtualMethods)
     }
 
-    fn after_set_attr(&self, attr: &Attr) {
-        self.super_type().unwrap().after_set_attr(attr);
-        self.add_remove_attr(attr);
-    }
-
-    fn before_remove_attr(&self, attr: &Attr) {
-        self.super_type().unwrap().before_remove_attr(attr);
-        self.add_remove_attr(attr);
+    fn attribute_mutated(&self, attr: &Attr, mutation: AttributeMutation) {
+        self.super_type().unwrap().attribute_mutated(attr, mutation);
+        if *attr.local_name() == atom!(href) {
+            document_from_node(self).refresh_base_element();
+        }
     }
 
     fn bind_to_tree(&self, tree_in_doc: bool) {