servo: Merge #13818 - Implement `selectedIndex` property on `<select>` (from frewsxcv:selected-index); r=KiChjang

Source-Repo: https://github.com/servo/servo
Source-Revision: 94ab5905f8757098faa915423f42225fd5328559

servo/components/script/dom/htmlselectelement.rs

@@ -299,6 +299,36 @@ impl HTMLSelectElementMethods for HTMLSelectElement {
             opt.set_selectedness(false);
         }
     }
+
+    // https://html.spec.whatwg.org/multipage/#dom-select-selectedindex
+    fn SelectedIndex(&self) -> i32 {
+        self.upcast::<Node>()
+            .traverse_preorder()
+            .filter_map(Root::downcast::<HTMLOptionElement>)
+            .enumerate()
+            .filter(|&(_, ref opt_elem)| opt_elem.Selected())
+            .map(|(i, _)| i as i32)
+            .next()
+            .unwrap_or(-1)
+    }
+
+    // https://html.spec.whatwg.org/multipage/#dom-select-selectedindex
+    fn SetSelectedIndex(&self, index: i32) {
+        let mut opt_iter = self.upcast::<Node>()
+                               .traverse_preorder()
+                               .filter_map(Root::downcast::<HTMLOptionElement>);
+        for opt in opt_iter.by_ref().take(index as usize) {
+            opt.set_selectedness(false);
+        }
+        if let Some(opt) = opt_iter.next() {
+            opt.set_selectedness(true);
+            opt.set_dirtiness(true);
+            // Reset remaining <option> elements
+            for opt in opt_iter {
+                opt.set_selectedness(false);
+            }
+        }
+    }
 }
 
 impl VirtualMethods for HTMLSelectElement {

servo/components/script/dom/webidls/HTMLSelectElement.webidl

@@ -25,7 +25,7 @@ interface HTMLSelectElement : HTMLElement {
   //setter void (unsigned long index, HTMLOptionElement? option);
 
   //readonly attribute HTMLCollection selectedOptions;
-  //         attribute long selectedIndex;
+  attribute long selectedIndex;
   attribute DOMString value;
 
   //readonly attribute boolean willValidate;