Auto merge of #11572 - nox:placeholder-shown, r=SimonSapin

Implement :placeholder-shown (fixes #10561)

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components/layout/wrapper.rs

@@ -561,7 +561,8 @@ impl<'le> ::selectors::Element for ServoLayoutElement<'le> {
             NonTSPseudoClass::Disabled |
             NonTSPseudoClass::Checked |
             NonTSPseudoClass::Indeterminate |
-            NonTSPseudoClass::ReadWrite =>
+            NonTSPseudoClass::ReadWrite |
+            NonTSPseudoClass::PlaceholderShown =>
                 self.element.get_state_for_layout().contains(pseudo_class.state_flag())
         }
     }

components/script/dom/element.rs

@@ -2222,7 +2222,8 @@ impl<'a> ::selectors::Element for Root<Element> {
             NonTSPseudoClass::Disabled |
             NonTSPseudoClass::Checked |
             NonTSPseudoClass::Indeterminate |
-            NonTSPseudoClass::ReadWrite =>
+            NonTSPseudoClass::ReadWrite |
+            NonTSPseudoClass::PlaceholderShown =>
                 Element::state(self).contains(pseudo_class.state_flag()),
         }
     }
@@ -2493,6 +2494,17 @@ impl Element {
     pub fn set_read_write_state(&self, value: bool) {
         self.set_state(IN_READ_WRITE_STATE, value)
     }
+
+    pub fn placeholder_shown_state(&self) -> bool {
+        self.state.get().contains(IN_PLACEHOLDER_SHOWN_STATE)
+    }
+
+    pub fn set_placeholder_shown_state(&self, value: bool) {
+        if self.placeholder_shown_state() != value {
+            self.set_state(IN_PLACEHOLDER_SHOWN_STATE, value);
+            self.upcast::<Node>().dirty(NodeDamage::OtherNodeDamage);
+        }
+    }
 }
 
 impl Element {

components/script/dom/htmlinputelement.rs

@@ -709,6 +709,17 @@ impl HTMLInputElement {
         self.value_changed.set(false);
         self.upcast::<Node>().dirty(NodeDamage::OtherNodeDamage);
     }
+
+    fn update_placeholder_shown_state(&self) {
+        match self.input_type.get() {
+            InputType::InputText | InputType::InputPassword => {},
+            _ => return,
+        }
+        let has_placeholder = !self.placeholder.borrow().is_empty();
+        let has_value = !self.textinput.borrow().is_empty();
+        let el = self.upcast::<Element>();
+        el.set_placeholder_shown_state(has_placeholder && !has_value);
+    }
 }
 
 impl VirtualMethods for HTMLInputElement {
@@ -757,6 +768,7 @@ impl VirtualMethods for HTMLInputElement {
                 self.size.set(size.unwrap_or(DEFAULT_INPUT_SIZE));
             }
             &atom!("type") => {
+                let el = self.upcast::<Element>();
                 match mutation {
                     AttributeMutation::Set(_) => {
                         let new_type = match attr.value().as_atom() {
@@ -774,7 +786,6 @@ impl VirtualMethods for HTMLInputElement {
                         let (old_value_mode, old_idl_value) = (self.value_mode(), self.Value());
                         self.input_type.set(new_type);
 
-                        let el = self.upcast::<Element>();
                         if new_type == InputType::InputText {
                             let read_write = !(self.ReadOnly() || el.disabled_state());
                             el.set_read_write_state(read_write);
@@ -831,11 +842,14 @@ impl VirtualMethods for HTMLInputElement {
                         el.set_read_write_state(read_write);
                     }
                 }
+
+                self.update_placeholder_shown_state();
             },
             &atom!("value") if !self.value_changed.get() => {
                 let value = mutation.new_value(attr).map(|value| (**value).to_owned());
                 self.textinput.borrow_mut().set_content(
                     value.map_or(DOMString::new(), DOMString::from));
+                self.update_placeholder_shown_state();
             },
             &atom!("name") if self.input_type.get() == InputType::InputRadio => {
                 self.radio_group_updated(
@@ -854,13 +868,15 @@ impl VirtualMethods for HTMLInputElement {
                 }
             }
             &atom!("placeholder") => {
-                // FIXME(ajeffrey): Should we do in-place mutation of the placeholder?
-                let mut placeholder = self.placeholder.borrow_mut();
-                placeholder.clear();
-                if let AttributeMutation::Set(_) = mutation {
-                    placeholder.extend(
-                        attr.value().chars().filter(|&c| c != '\n' && c != '\r'));
+                {
+                    let mut placeholder = self.placeholder.borrow_mut();
+                    placeholder.clear();
+                    if let AttributeMutation::Set(_) = mutation {
+                        placeholder.extend(
+                            attr.value().chars().filter(|&c| c != '\n' && c != '\r'));
+                    }
                 }
+                self.update_placeholder_shown_state();
             },
             &atom!("readonly") if self.input_type.get() == InputType::InputText => {
                 let el = self.upcast::<Element>();
@@ -936,6 +952,7 @@ impl VirtualMethods for HTMLInputElement {
                         },
                         DispatchInput => {
                             self.value_changed.set(true);
+                            self.update_placeholder_shown_state();
 
                             if event.IsTrusted() {
                                 let window = window_from_node(self);

components/script/textinput.rs

@@ -549,6 +549,11 @@ impl<T: ClipboardProvider> TextInput<T> {
         }
     }
 
+    /// Whether the content is empty.
+    pub fn is_empty(&self) -> bool {
+        self.lines.len() <= 1 && self.lines.get(0).map_or(true, |line| line.is_empty())
+    }
+
     /// The length of the content in bytes.
     pub fn len(&self) -> usize {
         self.lines.iter().fold(0, |m, l| {

components/style/element_state.rs

@@ -5,7 +5,7 @@
 bitflags! {
     #[doc = "Event-based element states."]
     #[derive(HeapSizeOf)]
-    pub flags ElementState: u8 {
+    pub flags ElementState: u16 {
         #[doc = "The mouse is down on this element. \
                  https://html.spec.whatwg.org/multipage/#selector-active \
                  FIXME(#7333): set/unset this when appropriate"]
@@ -29,5 +29,7 @@ bitflags! {
         const IN_INDETERMINATE_STATE = 0x40,
         #[doc = "https://html.spec.whatwg.org/multipage/#selector-read-write"]
         const IN_READ_WRITE_STATE = 0x80,
+        #[doc = "https://html.spec.whatwg.org/multipage/#selector-placeholder-shown"]
+        const IN_PLACEHOLDER_SHOWN_STATE = 0x0100,
     }
 }

components/style/selector_impl.rs

@@ -131,7 +131,8 @@ pub enum NonTSPseudoClass {
     Indeterminate,
     ServoNonZeroBorder,
     ReadWrite,
-    ReadOnly
+    ReadOnly,
+    PlaceholderShown,
 }
 
 impl NonTSPseudoClass {
@@ -147,6 +148,7 @@ impl NonTSPseudoClass {
             Checked => IN_CHECKED_STATE,
             Indeterminate => IN_INDETERMINATE_STATE,
             ReadOnly | ReadWrite => IN_READ_WRITE_STATE,
+            PlaceholderShown => IN_PLACEHOLDER_SHOWN_STATE,
 
             AnyLink |
             Link |
@@ -179,6 +181,7 @@ impl SelectorImpl for ServoSelectorImpl {
             "indeterminate" => Indeterminate,
             "read-write" => ReadWrite,
             "read-only" => ReadOnly,
+            "placeholder-shown" => PlaceholderShown,
             "-servo-nonzero-border" => {
                 if !context.in_user_agent_stylesheet {
                     return Err(());

ports/geckolib/wrapper.rs

@@ -352,7 +352,7 @@ impl<'le> TElement for GeckoElement<'le> {
 
     fn get_state(&self) -> ElementState {
         unsafe {
-            ElementState::from_bits_truncate(Gecko_ElementState(self.element))
+            ElementState::from_bits_truncate(Gecko_ElementState(self.element) as u16)
         }
     }