make Document.getElementsByName a live collection

2 files changed, 89 insertions, 14 deletions

diff --git a/components/script/dom/document.rs b/components/script/dom/document.rs
index 3049d4f0bd6..7c6fb00ae9a 100644
--- a/components/script/dom/document.rs
+++ b/components/script/dom/document.rs
@@ -3056,14 +3056,56 @@ impl Document {
         self.redirect_count.set(count)
     }
 
-    fn create_node_list<F: Fn(&Node) -> bool>(&self, callback: F) -> DomRoot<NodeList> {
+    pub fn elements_by_name_count(&self, name: &DOMString) -> u32 {
+        if name.is_empty() {
+            return 0;
+        }
+        self.count_node_list(|n| Document::is_element_in_get_by_name(n, name))
+    }
+
+    pub fn nth_element_by_name(&self, index: u32, name: &DOMString) -> Option<DomRoot<Node>> {
+        if name.is_empty() {
+            return None;
+        }
+        self.nth_in_node_list(index, |n| Document::is_element_in_get_by_name(n, name))
+    }
+
+    // Note that document.getByName does not match on the same conditions
+    // as the document named getter.
+    fn is_element_in_get_by_name(node: &Node, name: &DOMString) -> bool {
+        let element = match node.downcast::<Element>() {
+            Some(element) => element,
+            None => return false,
+        };
+        if element.namespace() != &ns!(html) {
+            return false;
+        }
+        element.get_name().map_or(false, |n| *n == **name)
+    }
+
+    fn count_node_list<F: Fn(&Node) -> bool>(&self, callback: F) -> u32 {
         let doc = self.GetDocumentElement();
         let maybe_node = doc.as_deref().map(Castable::upcast::<Node>);
-        let iter = maybe_node
+        maybe_node
             .iter()
             .flat_map(|node| node.traverse_preorder(ShadowIncluding::No))
-            .filter(|node| callback(&node));
-        NodeList::new_simple_list(&self.window, iter)
+            .filter(|node| callback(&node))
+            .count() as u32
+    }
+
+    fn nth_in_node_list<F: Fn(&Node) -> bool>(
+        &self,
+        index: u32,
+        callback: F,
+    ) -> Option<DomRoot<Node>> {
+        let doc = self.GetDocumentElement();
+        let maybe_node = doc.as_deref().map(Castable::upcast::<Node>);
+        maybe_node
+            .iter()
+            .flat_map(|node| node.traverse_preorder(ShadowIncluding::No))
+            .filter(|node| callback(&node))
+            .nth(index as usize)
+            .map(|n| DomRoot::from_ref(&*n))
     }
 
     fn get_html_element(&self) -> Option<DomRoot<HTMLHtmlElement>> {
@@ -4244,16 +4286,7 @@ impl DocumentMethods for Document {
 
     // https://html.spec.whatwg.org/multipage/#dom-document-getelementsbyname
     fn GetElementsByName(&self, name: DOMString) -> DomRoot<NodeList> {
-        self.create_node_list(|node| {
-            let element = match node.downcast::<Element>() {
-                Some(element) => element,
-                None => return false,
-            };
-            if element.namespace() != &ns!(html) {
-                return false;
-            }
-            element.get_name().map_or(false, |atom| *atom == *name)
-        })
+        NodeList::new_elements_by_name_list(self.window(), self, name)
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-document-images
diff --git a/components/script/dom/nodelist.rs b/components/script/dom/nodelist.rs
index 8c4f6d39358..5218d1b3026 100644
--- a/components/script/dom/nodelist.rs
+++ b/components/script/dom/nodelist.rs
@@ -7,6 +7,8 @@ use crate::dom::bindings::codegen::Bindings::NodeListBinding;
 use crate::dom::bindings::codegen::Bindings::NodeListBinding::NodeListMethods;
 use crate::dom::bindings::reflector::{reflect_dom_object, Reflector};
 use crate::dom::bindings::root::{Dom, DomRoot, MutNullableDom};
+use crate::dom::bindings::str::DOMString;
+use crate::dom::document::Document;
 use crate::dom::htmlelement::HTMLElement;
 use crate::dom::htmlformelement::HTMLFormElement;
 use crate::dom::node::{ChildrenMutation, Node};
@@ -22,6 +24,7 @@ pub enum NodeListType {
     Children(ChildrenList),
     Labels(LabelsList),
     Radio(RadioList),
+    ElementsByName(ElementsByNameList),
 }
 
 // https://dom.spec.whatwg.org/#interface-nodelist
@@ -74,6 +77,17 @@ impl NodeList {
         NodeList::new(window, NodeListType::Labels(LabelsList::new(element)))
     }
 
+    pub fn new_elements_by_name_list(
+        window: &Window,
+        document: &Document,
+        name: DOMString,
+    ) -> DomRoot<NodeList> {
+        NodeList::new(
+            window,
+            NodeListType::ElementsByName(ElementsByNameList::new(document, name)),
+        )
+    }
+
     pub fn empty(window: &Window) -> DomRoot<NodeList> {
         NodeList::new(window, NodeListType::Simple(vec![]))
     }
@@ -87,6 +101,7 @@ impl NodeListMethods for NodeList {
             NodeListType::Children(ref list) => list.len(),
             NodeListType::Labels(ref list) => list.len(),
             NodeListType::Radio(ref list) => list.len(),
+            NodeListType::ElementsByName(ref list) => list.len(),
         }
     }
 
@@ -99,6 +114,7 @@ impl NodeListMethods for NodeList {
             NodeListType::Children(ref list) => list.item(index),
             NodeListType::Labels(ref list) => list.item(index),
             NodeListType::Radio(ref list) => list.item(index),
+            NodeListType::ElementsByName(ref list) => list.item(index),
         }
     }
 
@@ -401,3 +417,29 @@ impl RadioList {
         self.form.nth_for_radio_list(index, self.mode, &self.name)
     }
 }
+
+#[derive(JSTraceable, MallocSizeOf)]
+#[unrooted_must_root_lint::must_root]
+pub struct ElementsByNameList {
+    document: Dom<Document>,
+    name: DOMString,
+}
+
+impl ElementsByNameList {
+    pub fn new(document: &Document, name: DOMString) -> ElementsByNameList {
+        ElementsByNameList {
+            document: Dom::from_ref(document),
+            name: name,
+        }
+    }
+
+    pub fn len(&self) -> u32 {
+        self.document.elements_by_name_count(&self.name)
+    }
+
+    pub fn item(&self, index: u32) -> Option<DomRoot<Node>> {
+        self.document
+            .nth_element_by_name(index, &self.name)
+            .and_then(|n| Some(DomRoot::from_ref(&*n)))
+    }
+}