Refactor the locate a namespace algorithm

Cargo.lock

@@ -2110,6 +2110,11 @@ dependencies = [
  "rand 0.3.14 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "ref_filter_map"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "ref_slice"
 version = "1.1.0"
@@ -2200,6 +2205,7 @@ dependencies = [
  "profile_traits 0.0.1",
  "rand 0.3.14 (registry+https://github.com/rust-lang/crates.io-index)",
  "range 0.0.1",
+ "ref_filter_map 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "ref_slice 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "regex 0.1.76 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-serialize 0.3.19 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -3356,6 +3362,7 @@ dependencies = [
 "checksum quote 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)" = "ea1e0c9bc6bfb0a60d539aab6e338207c1a5456e62f5bd5375132cee119aa4b3"
 "checksum rand 0.3.14 (registry+https://github.com/rust-lang/crates.io-index)" = "2791d88c6defac799c3f20d74f094ca33b9332612d9aef9078519c82e4fe04a5"
 "checksum rayon 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)" = "3b6a6e05e0e6b703e9f2ad266eb63f3712e693a17a2702b95a23de14ce8defa9"
+"checksum ref_filter_map 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)" = "2b5ceb840e4009da4841ed22a15eb49f64fdd00a2138945c5beacf506b2fb5ed"
 "checksum ref_slice 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "546bb4aa91c85f232732cc5b3c8097ea97ae9a77304f9ab4df8b203ff7672dad"
 "checksum regex 0.1.76 (registry+https://github.com/rust-lang/crates.io-index)" = "63b49f873f36ddc838d773972511e5fed2ef7350885af07d58e2f48ce8073dcd"
 "checksum regex-syntax 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)" = "279401017ae31cf4e15344aa3f085d0e2e5c1e70067289ef906906fdbe92c8fd"

components/script/Cargo.toml

@@ -61,6 +61,7 @@ plugins = {path = "../plugins"}
 profile_traits = {path = "../profile_traits"}
 rand = "0.3"
 range = {path = "../range"}
+ref_filter_map = "1.0.1"
 ref_slice = "1.0"
 regex = "0.1.43"
 rustc-serialize = "0.3"

components/script/dom/element.rs

@@ -73,6 +73,7 @@ use html5ever::serialize::TraversalScope::{ChildrenOnly, IncludeNode};
 use html5ever::tree_builder::{LimitedQuirks, NoQuirks, Quirks};
 use html5ever_atoms::{Prefix, LocalName, Namespace, QualName};
 use parking_lot::RwLock;
+use ref_filter_map::ref_filter_map;
 use selectors::matching::{ElementFlags, MatchingReason, matches};
 use selectors::matching::{HAS_EDGE_CHILD_SELECTOR, HAS_SLOW_SELECTOR, HAS_SLOW_SELECTOR_LATER_SIBLINGS};
 use selectors::parser::{AttrSelector, NamespaceConstraint};
@@ -722,6 +723,46 @@ impl Element {
         Ref::map(self.attrs.borrow(), |attrs| &**attrs)
     }
 
+    // Element branch of https://dom.spec.whatwg.org/#locate-a-namespace
+    pub fn locate_namespace(&self, prefix: Option<DOMString>) -> Namespace {
+        let prefix = prefix.map(String::from).map(LocalName::from);
+
+        let inclusive_ancestor_elements =
+            self.upcast::<Node>()
+                .inclusive_ancestors()
+                .filter_map(Root::downcast::<Self>);
+
+        // Steps 3-4.
+        for element in inclusive_ancestor_elements {
+            // Step 1.
+            if element.namespace() != &ns!() && element.prefix().map(|p| &**p) == prefix.as_ref().map(|p| &**p) {
+                return element.namespace().clone();
+            }
+
+            // Step 2.
+            let attr = ref_filter_map(self.attrs(), |attrs| {
+                attrs.iter().find(|attr| {
+                    if attr.namespace() != &ns!(xmlns) {
+                        return false;
+                    }
+                    match (attr.prefix(), prefix.as_ref()) {
+                        (Some(&namespace_prefix!("xmlns")), Some(prefix)) => {
+                            attr.local_name() == prefix
+                        },
+                        (None, None) => attr.local_name() == &local_name!("xmlns"),
+                        _ => false,
+                    }
+                })
+            });
+
+            if let Some(attr) = attr {
+                return (**attr.value()).into();
+            }
+        }
+
+        ns!()
+    }
+
     pub fn style_attribute(&self) -> &DOMRefCell<Option<Arc<RwLock<PropertyDeclarationBlock>>>> {
         &self.style_attribute
     }

components/script/dom/node.rs

@@ -7,8 +7,6 @@
 use app_units::Au;
 use devtools_traits::NodeInfo;
 use document_loader::DocumentLoader;
-use dom::attr::Attr;
-use dom::bindings::codegen::Bindings::AttrBinding::AttrMethods;
 use dom::bindings::codegen::Bindings::CharacterDataBinding::CharacterDataMethods;
 use dom::bindings::codegen::Bindings::DocumentBinding::DocumentMethods;
 use dom::bindings::codegen::Bindings::ElementBinding::ElementMethods;
@@ -60,7 +58,7 @@ use euclid::rect::Rect;
 use euclid::size::Size2D;
 use heapsize::{HeapSizeOf, heap_size_of};
 use html5ever::tree_builder::QuirksMode;
-use html5ever_atoms::{Prefix, LocalName, Namespace, QualName};
+use html5ever_atoms::{Prefix, Namespace, QualName};
 use js::jsapi::{JSContext, JSObject, JSRuntime};
 use libc::{self, c_void, uintptr_t};
 use msg::constellation_msg::PipelineId;
@@ -1811,67 +1809,19 @@ impl Node {
 
     // https://dom.spec.whatwg.org/#locate-a-namespace
     pub fn locate_namespace(node: &Node, prefix: Option<DOMString>) -> Namespace {
-        fn attr_defines_namespace(attr: &Attr,
-                                  defined_prefix: &Option<LocalName>) -> bool {
-            *attr.namespace() == ns!(xmlns) &&
-                match (attr.prefix(), defined_prefix) {
-                    (Some(attr_prefix), &Some(ref defined_prefix)) =>
-                        attr_prefix == &namespace_prefix!("xmlns") &&
-                            attr.local_name() == defined_prefix,
-                    (None, &None) => *attr.local_name() == local_name!("xmlns"),
-                    _ => false
-                }
-        }
-
         match node.type_id() {
             NodeTypeId::Element(_) => {
-                let element = node.downcast::<Element>().unwrap();
+                node.downcast::<Element>().unwrap().locate_namespace(prefix)
-                // Step 1.
-                if *element.namespace() != ns!() && element.prefix() == prefix.as_ref() {
-                    return element.namespace().clone()
-                }
-
-                // Even though this is conceptually a namespace prefix,
-                // in the `xmlns:foo="https://example.net/namespace" declaration
-                // it is a local name.
-                // FIXME(ajeffrey): directly convert DOMString to LocalName
-                let prefix_atom = prefix.as_ref().map(|s| LocalName::from(&**s));
-
-                // Step 2.
-                let attrs = element.attrs();
-                let namespace_attr = attrs.iter().find(|attr| {
-                    attr_defines_namespace(attr, &prefix_atom)
-                });
-
-                // Steps 2.1-2.
-                if let Some(attr) = namespace_attr {
-                    return namespace_from_domstring(Some(attr.Value()));
-                }
-
-                match node.GetParentElement() {
-                    // Step 3.
-                    None => ns!(),
-                    // Step 4.
-                    Some(parent) => Node::locate_namespace(parent.upcast(), prefix)
-                }
             },
             NodeTypeId::Document(_) => {
-                match node.downcast::<Document>().unwrap().GetDocumentElement().r() {
+                node.downcast::<Document>().unwrap()
-                    // Step 1.
+                    .GetDocumentElement().as_ref()
-                    None => ns!(),
+                    .map_or(ns!(), |elem| elem.locate_namespace(prefix))
-                    // Step 2.
-                    Some(document_element) => {
-                        Node::locate_namespace(document_element.upcast(), prefix)
-                    }
-                }
             },
-            NodeTypeId::DocumentType => ns!(),
+            NodeTypeId::DocumentType | NodeTypeId::DocumentFragment => ns!(),
-            NodeTypeId::DocumentFragment => ns!(),
+            _ => {
-            _ => match node.GetParentElement() {
+                node.GetParentElement().as_ref()
-                     // Step 1.
+                    .map_or(ns!(), |elem| elem.locate_namespace(prefix))
-                     None => ns!(),
-                     // Step 2.
-                     Some(parent) => Node::locate_namespace(parent.upcast(), prefix)
             }
         }
     }

components/script/lib.rs

@@ -74,6 +74,7 @@ extern crate phf;
 extern crate profile_traits;
 extern crate rand;
 extern crate range;
+extern crate ref_filter_map;
 extern crate ref_slice;
 extern crate regex;
 extern crate rustc_serialize;