Auto merge of #7963 - dagnir:issue-7774, r=eefriedman

Implement ask_for_reset for HTMLSelectElement.

Fixes #7774

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components/script/dom/htmloptionelement.rs

@@ -14,6 +14,7 @@ use dom::document::Document;
 use dom::element::{AttributeMutation, Element, IN_ENABLED_STATE};
 use dom::htmlelement::HTMLElement;
 use dom::htmlscriptelement::HTMLScriptElement;
+use dom::htmlselectelement::HTMLSelectElement;
 use dom::node::Node;
 use dom::text::Text;
 use dom::virtualmethods::VirtualMethods;
@@ -51,6 +52,21 @@ impl HTMLOptionElement {
         let element = HTMLOptionElement::new_inherited(localName, prefix, document);
         Node::reflect_node(box element, document, HTMLOptionElementBinding::Wrap)
     }
+
+    pub fn set_selectedness(&self, selected: bool) {
+        self.selectedness.set(selected);
+    }
+
+    fn pick_if_selected_and_reset(&self) {
+        if let Some(select) = self.upcast::<Node>().ancestors()
+                .filter_map(Root::downcast::<HTMLSelectElement>)
+                .next() {
+            if self.Selected() {
+                select.pick_option(self);
+            }
+            select.ask_for_reset();
+        }
+    }
 }
 
 fn collect_text(element: &Element, value: &mut DOMString) {
@@ -134,8 +150,7 @@ impl HTMLOptionElementMethods for HTMLOptionElement {
     fn SetSelected(&self, selected: bool) {
         self.dirtiness.set(true);
         self.selectedness.set(selected);
-        // FIXME: as per the spec, implement 'ask for a reset'
-        // https://github.com/servo/servo/issues/7774
+        self.pick_if_selected_and_reset();
     }
 }
 
@@ -187,6 +202,8 @@ impl VirtualMethods for HTMLOptionElement {
         }
 
         self.upcast::<Element>().check_parent_disabled_state_for_option();
+
+        self.pick_if_selected_and_reset();
     }
 
     fn unbind_from_tree(&self, tree_in_doc: bool) {

components/script/dom/htmlselectelement.rs

@@ -3,6 +3,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::attr::{Attr, AttrValue};
+use dom::bindings::codegen::Bindings::HTMLOptionElementBinding::HTMLOptionElementMethods;
 use dom::bindings::codegen::Bindings::HTMLSelectElementBinding;
 use dom::bindings::codegen::Bindings::HTMLSelectElementBinding::HTMLSelectElementMethods;
 use dom::bindings::codegen::UnionTypes::HTMLElementOrLong;
@@ -14,6 +15,7 @@ use dom::element::{AttributeMutation, Element, IN_ENABLED_STATE};
 use dom::htmlelement::HTMLElement;
 use dom::htmlfieldsetelement::HTMLFieldSetElement;
 use dom::htmlformelement::{FormControl, HTMLFormElement};
+use dom::htmloptionelement::HTMLOptionElement;
 use dom::node::{Node, window_from_node};
 use dom::validitystate::ValidityState;
 use dom::virtualmethods::VirtualMethods;
@@ -46,6 +48,64 @@ impl HTMLSelectElement {
         let element = HTMLSelectElement::new_inherited(localName, prefix, document);
         Node::reflect_node(box element, document, HTMLSelectElementBinding::Wrap)
     }
+
+    // https://html.spec.whatwg.org/multipage/#ask-for-a-reset
+    pub fn ask_for_reset(&self) {
+        if self.Multiple() {
+            return;
+        }
+
+        let mut first_enabled: Option<Root<HTMLOptionElement>> = None;
+        let mut last_selected: Option<Root<HTMLOptionElement>> = None;
+
+        let node = self.upcast::<Node>();
+        for opt in node.traverse_preorder().filter_map(Root::downcast::<HTMLOptionElement>) {
+            if opt.Selected() {
+                opt.set_selectedness(false);
+                last_selected = Some(Root::from_ref(opt.r()));
+            }
+            let element = opt.upcast::<Element>();
+            if first_enabled.is_none() && !element.get_disabled_state() {
+                first_enabled = Some(Root::from_ref(opt.r()));
+            }
+        }
+
+        if let Some(last_selected) = last_selected {
+            last_selected.set_selectedness(true);
+        } else {
+            if self.display_size() == 1 {
+                if let Some(first_enabled) = first_enabled {
+                    first_enabled.set_selectedness(true);
+                }
+            }
+        }
+    }
+
+    // https://html.spec.whatwg.org/multipage/#concept-select-pick
+    pub fn pick_option(&self, picked: &HTMLOptionElement) {
+        if !self.Multiple() {
+            let node = self.upcast::<Node>();
+            let picked = picked.upcast();
+            for opt in node.traverse_preorder().filter_map(Root::downcast::<HTMLOptionElement>) {
+                if opt.upcast::<HTMLElement>() != picked {
+                    opt.set_selectedness(false);
+                }
+            }
+        }
+    }
+
+    // https://html.spec.whatwg.org/multipage/#concept-select-size
+    fn display_size(&self) -> u32 {
+         if self.Size() == 0 {
+             if self.Multiple() {
+                 4
+             } else {
+                 1
+             }
+         } else {
+             self.Size()
+         }
+     }
 }
 
 impl HTMLSelectElementMethods for HTMLSelectElement {