style: Share code for Element::Closest.

components/script/dom/element.rs

@@ -2217,26 +2217,18 @@ impl ElementMethods for Element {
 
     // https://dom.spec.whatwg.org/#dom-element-closest
     fn Closest(&self, selectors: DOMString) -> Fallible<Option<DomRoot<Element>>> {
+        let selectors =
             match SelectorParser::parse_author_origin_no_namespace(&selectors) {
-            Err(_) => Err(Error::Syntax),
-            Ok(selectors) => {
-                let self_root = DomRoot::from_ref(self);
-                let root = self.upcast::<Node>();
-                for element in root.inclusive_ancestors() {
-                    if let Some(element) = DomRoot::downcast::<Element>(element) {
+                Err(_) => return Err(Error::Syntax),
+                Ok(selectors) => selectors,
+            };
+
         let quirks_mode = document_from_node(self).quirks_mode();
-                        // FIXME(bholley): Consider an nth-index cache here.
-                        let mut ctx = MatchingContext::new(MatchingMode::Normal, None, None,
-                                                           quirks_mode);
-                        ctx.scope_element = Some(self_root.opaque());
-                        if matches_selector_list(&selectors, &element, &mut ctx) {
-                            return Ok(Some(element));
-                        }
-                    }
-                }
-                Ok(None)
-            }
-        }
+        Ok(dom_apis::element_closest(
+            DomRoot::from_ref(self),
+            &selectors,
+            quirks_mode,
+        ))
     }
 
     // https://dom.spec.whatwg.org/#dom-element-insertadjacentelement

components/style/dom_apis.rs

@@ -6,7 +6,7 @@
 //! and Gecko.
 
 use context::QuirksMode;
-use selectors::{Element, SelectorList};
+use selectors::{Element, NthIndexCache, SelectorList};
 use selectors::matching::{self, MatchingContext, MatchingMode};
 
 /// https://dom.spec.whatwg.org/#dom-element-matches
@@ -27,3 +27,33 @@ where
     context.scope_element = Some(element.opaque());
     matching::matches_selector_list(selector_list, element, &mut context)
 }
+
+/// https://dom.spec.whatwg.org/#dom-element-closest
+pub fn element_closest<E>(
+    element: E,
+    selector_list: &SelectorList<E::Impl>,
+    quirks_mode: QuirksMode,
+) -> Option<E>
+where
+    E: Element,
+{
+    let mut nth_index_cache = NthIndexCache::default();
+
+    let mut context = MatchingContext::new(
+        MatchingMode::Normal,
+        None,
+        Some(&mut nth_index_cache),
+        quirks_mode,
+    );
+    context.scope_element = Some(element.opaque());
+
+    let mut current = Some(element);
+    while let Some(element) = current.take() {
+        if matching::matches_selector_list(selector_list, &element, &mut context) {
+            return Some(element);
+        }
+        current = element.parent_element();
+    }
+
+    return None;
+}

ports/geckolib/glue.rs

@@ -6,7 +6,7 @@ use cssparser::{Parser, ParserInput};
 use cssparser::ToCss as ParserToCss;
 use env_logger::LogBuilder;
 use malloc_size_of::MallocSizeOfOps;
-use selectors::{self, Element, NthIndexCache};
+use selectors::Element;
 use selectors::matching::{MatchingContext, MatchingMode, matches_selector};
 use servo_arc::{Arc, ArcBorrow, RawOffsetArc};
 use std::cell::RefCell;
@@ -1526,28 +1526,13 @@ pub unsafe extern "C" fn Servo_SelectorList_Closest<'a>(
     selectors: RawServoSelectorListBorrowed,
 ) -> RawGeckoElementBorrowedOrNull<'a> {
     use std::borrow::Borrow;
-
-    let mut nth_index_cache = NthIndexCache::default();
+    use style::dom_apis;
 
     let element = GeckoElement(element);
-    let mut context = MatchingContext::new(
-        MatchingMode::Normal,
-        None,
-        Some(&mut nth_index_cache),
-        element.owner_document_quirks_mode(),
-    );
-    context.scope_element = Some(element.opaque());
-
     let selectors = ::selectors::SelectorList::from_ffi(selectors).borrow();
-    let mut current = Some(element);
-    while let Some(element) = current.take() {
-        if selectors::matching::matches_selector_list(&selectors, &element, &mut context) {
-            return Some(element.0);
-        }
-        current = element.parent_element();
-    }
 
-    return None;
+    dom_apis::element_closest(element, &selectors, element.owner_document_quirks_mode())
+        .map(|e| e.0)
 }
 
 #[no_mangle]