Properly implement HTMLProgressElement DOM code

Signed-off-by: Erik Funder Carstensen <fundererik@gmail.com>

components/script/dom/htmlprogresselement.rs

@@ -4,8 +4,10 @@
 
 use crate::dom::bindings::codegen::Bindings::HTMLProgressElementBinding::HTMLProgressElementMethods;
 use crate::dom::bindings::inheritance::Castable;
+use crate::dom::bindings::num::Finite;
 use crate::dom::bindings::root::{DomRoot, MutNullableDom};
 use crate::dom::document::Document;
+use crate::dom::element::Element;
 use crate::dom::htmlelement::HTMLElement;
 use crate::dom::node::Node;
 use crate::dom::nodelist::NodeList;
@@ -48,4 +50,76 @@ impl HTMLProgressElement {
 impl HTMLProgressElementMethods for HTMLProgressElement {
     // https://html.spec.whatwg.org/multipage/#dom-lfe-labels
     make_labels_getter!(Labels, labels_node_list);
+
+    // https://html.spec.whatwg.org/multipage/#dom-progress-value
+    fn Value(&self) -> Finite<f64> {
+        // In case of missing `value`, parse error, or negative `value`, `value` should be
+        // interpreted as 0.  As `get_string_attribute` returns an empty string in case the
+        // attribute is missing, this case is handeled as the default of the `map_or` function.
+        //
+        // It is safe to wrap the number coming from `parse_floating_point_number` as it will
+        // return Err on inf and nan
+        self.upcast::<Element>()
+            .get_string_attribute(&local_name!("value"))
+            .parse_floating_point_number()
+            .map_or(Finite::wrap(0.0), |v| {
+                if v < 0.0 {
+                    Finite::wrap(0.0)
+                } else {
+                    Finite::wrap(v.min(*self.Max()))
+                }
+            })
+    }
+
+    // https://html.spec.whatwg.org/multipage/#dom-progress-value
+    fn SetValue(&self, new_val: Finite<f64>) {
+        if 0.0 <= *new_val {
+            self.upcast::<Element>()
+                .set_string_attribute(&local_name!("value"), (*new_val).to_string().into());
+        }
+    }
+
+    // https://html.spec.whatwg.org/multipage/#dom-progress-max
+    fn Max(&self) -> Finite<f64> {
+        // In case of missing `max`, parse error, or negative `max`, `max` should be interpreted as
+        // 1.0. As `get_string_attribute` returns an empty string in case the attribute is missing,
+        // these cases are handeled by `map_or`
+        self.upcast::<Element>()
+            .get_string_attribute(&local_name!("max"))
+            .parse_floating_point_number()
+            .map_or(Finite::wrap(1.0), |m| {
+                if m <= 0.0 {
+                    Finite::wrap(1.0)
+                } else {
+                    Finite::wrap(m)
+                }
+            })
+    }
+
+    // https://html.spec.whatwg.org/multipage/#dom-progress-max
+    fn SetMax(&self, new_val: Finite<f64>) {
+        self.upcast::<Element>()
+            .set_string_attribute(&local_name!("max"), (*new_val).to_string().into());
+    }
+
+    // https://html.spec.whatwg.org/multipage/#dom-progress-position
+    fn Position(&self) -> Finite<f64> {
+        let value = self
+            .upcast::<Element>()
+            .get_string_attribute(&local_name!("value"));
+        if value.is_empty() {
+            Finite::wrap(-1.0)
+        } else {
+            let value = self.Value();
+            let max = self.Max();
+            // An unsafe Finite constructor might be nice here, as it's unlikely for the
+            // compiler to infer the following guarantees. It is probably premature
+            // optimization though.
+            //
+            // Safety: `ret` have to be a finite, defined number. This is the case since both
+            // value and max is finite, max > 0, and a value >> max cannot exist, as
+            // Self::Value(&self) enforces value <= max.
+            Finite::wrap(*value / *max)
+        }
+    }
 }

components/script/dom/webidls/HTMLProgressElement.webidl

@@ -7,10 +7,10 @@
 interface HTMLProgressElement : HTMLElement {
   [HTMLConstructor] constructor();
 
-  // [CEReactions]
-  //          attribute double value;
-  // [CEReactions]
-  //          attribute double max;
-  // readonly attribute double position;
+  [CEReactions]
+           attribute double value;
+  [CEReactions]
+           attribute double max;
+  readonly attribute double position;
   readonly attribute NodeList labels;
 };