Auto merge of #13066 - mskrzypkows:htmlselect_index, r=KiChjang

Implement indexed access on select elements

<!-- Please describe your changes on the following line: -->
Added methods for indexed access on select: SetLength, Length, Item, IndexedGetter

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #11763 (github issue number if applicable).

<!-- Either: -->
- [x] There are tests for these changes OR
- [ ] These changes do not require tests because _____

<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->

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components/script/dom/htmlselectelement.rs

@@ -6,6 +6,7 @@ use dom::attr::Attr;
 use dom::bindings::codegen::Bindings::HTMLOptionElementBinding::HTMLOptionElementMethods;
 use dom::bindings::codegen::Bindings::HTMLSelectElementBinding;
 use dom::bindings::codegen::Bindings::HTMLSelectElementBinding::HTMLSelectElementMethods;
+use dom::bindings::codegen::Bindings::NodeBinding::NodeMethods;
 use dom::bindings::codegen::UnionTypes::HTMLElementOrLong;
 use dom::bindings::codegen::UnionTypes::HTMLOptionElementOrHTMLOptGroupElement;
 use dom::bindings::inheritance::Castable;
@@ -17,7 +18,7 @@ use dom::htmlelement::HTMLElement;
 use dom::htmlfieldsetelement::HTMLFieldSetElement;
 use dom::htmlformelement::{FormDatumValue, FormControl, FormDatum, HTMLFormElement};
 use dom::htmloptionelement::HTMLOptionElement;
-use dom::node::{Node, UnbindContext, window_from_node};
+use dom::node::{document_from_node, Node, UnbindContext, window_from_node};
 use dom::nodelist::NodeList;
 use dom::validation::Validatable;
 use dom::validitystate::ValidityState;
@@ -183,6 +184,50 @@ impl HTMLSelectElementMethods for HTMLSelectElement {
     fn Labels(&self) -> Root<NodeList> {
         self.upcast::<HTMLElement>().labels()
     }
+
+    // https://html.spec.whatwg.org/multipage/#dom-select-length
+    fn SetLength(&self, value: u32) {
+        let length  = self.Length();
+        let node = self.upcast::<Node>();
+        if value < length {     // truncate the number of option elements
+            let mut iter = node.rev_children().take((length - value) as usize);
+            while let Some(child) = iter.next() {
+                if let Err(e) = node.RemoveChild(&child) {
+                    warn!("Error removing child of HTMLSelectElement: {:?}", e);
+                }
+            }
+        } else if value > length {  // add new blank option elements
+            let document = document_from_node(self);
+            for _ in 0..(value - length) {
+                let element = HTMLOptionElement::new(atom!("option"), None, &document.upcast());
+                if let Err(e) = node.AppendChild(element.upcast()) {
+                    warn!("error appending child of HTMLSelectElement: {:?}", e);
+                }
+            }
+        }
+    }
+
+    // https://html.spec.whatwg.org/multipage/#dom-select-length
+    fn Length(&self) -> u32 {
+        self.upcast::<Node>()
+            .traverse_preorder()
+            .filter_map(Root::downcast::<HTMLOptionElement>)
+            .count() as u32
+    }
+
+    // https://html.spec.whatwg.org/multipage/#dom-select-item
+    fn Item(&self, index: u32) -> Option<Root<Element>> {
+        self.upcast::<Node>()
+            .traverse_preorder()
+            .filter_map(Root::downcast::<HTMLOptionElement>)
+            .nth(index as usize)
+            .map(|item| Root::from_ref(item.upcast()))
+    }
+
+    // https://html.spec.whatwg.org/multipage/#dom-select-item
+    fn IndexedGetter(&self, index: u32) -> Option<Root<Element>> {
+        self.Item(index)
+    }
 }
 
 impl VirtualMethods for HTMLSelectElement {

components/script/dom/webidls/HTMLSelectElement.webidl

@@ -15,8 +15,8 @@ interface HTMLSelectElement : HTMLElement {
   readonly attribute DOMString type;
 
   //readonly attribute HTMLOptionsCollection options;
-  //         attribute unsigned long length;
+           attribute unsigned long length;
-  //getter Element? item(unsigned long index);
+  getter Element? item(unsigned long index);
   //HTMLOptionElement? namedItem(DOMString name);
   // Note: this function currently only exists for union.html.
   void add((HTMLOptionElement or HTMLOptGroupElement) element, optional (HTMLElement or long)? before = null);

tests/wpt/metadata/FileAPI/blob/Blob-constructor.html.ini

@@ -16,10 +16,6 @@
     expected: FAIL
     bug: https://github.com/servo/servo/issues/10911
 
-  [Passing an platform object that supports indexed properties as the blobParts array should work (select).]
-    expected: FAIL
-    bug: https://github.com/servo/servo/issues/11763
-
   [Passing a FrozenArray as the blobParts array should work (FrozenArray<MessagePort>).]
     expected: FAIL
     bug: https://github.com/servo/servo/issues/7457

tests/wpt/metadata/html/dom/interfaces.html.ini

@@ -3750,12 +3750,6 @@
   [HTMLSelectElement interface: attribute options]
     expected: FAIL
 
-  [HTMLSelectElement interface: attribute length]
-    expected: FAIL
-
-  [HTMLSelectElement interface: operation item(unsigned long)]
-    expected: FAIL
-
   [HTMLSelectElement interface: operation namedItem(DOMString)]
     expected: FAIL
 
@@ -3801,15 +3795,6 @@
   [HTMLSelectElement interface: document.createElement("select") must inherit property "options" with the proper type (9)]
     expected: FAIL
 
-  [HTMLSelectElement interface: document.createElement("select") must inherit property "length" with the proper type (10)]
-    expected: FAIL
-
-  [HTMLSelectElement interface: document.createElement("select") must inherit property "item" with the proper type (11)]
-    expected: FAIL
-
-  [HTMLSelectElement interface: calling item(unsigned long) on document.createElement("select") with too few arguments must throw TypeError]
-    expected: FAIL
-
   [HTMLSelectElement interface: document.createElement("select") must inherit property "namedItem" with the proper type (12)]
     expected: FAIL
 
@@ -10679,4 +10664,3 @@
 
   [Navigator interface: window.navigator must inherit property "hardwareConcurrency" with the proper type (22)]
     expected: FAIL
-

tests/wpt/metadata/html/semantics/forms/the-select-element/common-HTMLOptionsCollection.html.ini

@@ -1,18 +0,0 @@
-[common-HTMLOptionsCollection.html]
-  type: testharness
-  [On getting, the length attribute must return the number of nodes represented by the collection.]
-    expected: FAIL
-    bug: https://github.com/servo/servo/issues/11763
-
-  [Changing the length adds new nodes; The number of new nodes = new length minus old length]
-    expected: FAIL
-    bug: https://github.com/servo/servo/issues/11763
-
-  [New nodes have no value]
-    expected: FAIL
-    bug: https://github.com/servo/servo/issues/11763
-
-  [Setting a length equal to existing length changes nothing]
-    expected: FAIL
-    bug: https://github.com/servo/servo/issues/11763
-