style: [css-lists-3] Make 'none' invalid as a <counter-style> in coun…

…ter()/counters().

CSSWG resolution:
w3c/csswg-drafts#4163 (comment)

Spec:
https://drafts.csswg.org/css-lists-3/#counter-functions

Differential Revision: https://phabricator.services.mozilla.com/D43893

components/style/gecko/values.rs

@@ -8,7 +8,7 @@
 
 use crate::counter_style::{Symbol, Symbols};
 use crate::gecko_bindings::structs::CounterStylePtr;
-use crate::values::generics::CounterStyleOrNone;
+use crate::values::generics::CounterStyle;
 use crate::values::Either;
 use crate::Atom;
 use app_units::Au;
@@ -49,19 +49,17 @@ pub fn round_border_to_device_pixels(width: Au, au_per_device_px: Au) -> Au {
     }
 }
 
-impl CounterStyleOrNone {
+impl CounterStyle {
     /// Convert this counter style to a Gecko CounterStylePtr.
     pub fn to_gecko_value(self, gecko_value: &mut CounterStylePtr) {
         use crate::gecko_bindings::bindings::Gecko_SetCounterStyleToName as set_name;
         use crate::gecko_bindings::bindings::Gecko_SetCounterStyleToSymbols as set_symbols;
         match self {
-            CounterStyleOrNone::None => unsafe {
-                set_name(gecko_value, atom!("none").into_addrefed());
-            },
-            CounterStyleOrNone::Name(name) => unsafe {
+            CounterStyle::Name(name) => unsafe {
+                debug_assert_ne!(name.0, atom!("none"));
                 set_name(gecko_value, name.0.into_addrefed());
             },
-            CounterStyleOrNone::Symbols(symbols_type, symbols) => {
+            CounterStyle::Symbols(symbols_type, symbols) => {
                 let symbols: Vec<_> = symbols
                     .0
                     .iter()
@@ -86,7 +84,7 @@ impl CounterStyleOrNone {
         }
     }
 
-    /// Convert Gecko CounterStylePtr to CounterStyleOrNone or String.
+    /// Convert Gecko CounterStylePtr to CounterStyle or String.
     pub fn from_gecko_value(gecko_value: &CounterStylePtr) -> Either<Self, String> {
         use crate::gecko_bindings::bindings;
         use crate::values::generics::SymbolsType;
@@ -95,11 +93,8 @@ impl CounterStyleOrNone {
         let name = unsafe { bindings::Gecko_CounterStyle_GetName(gecko_value) };
         if !name.is_null() {
             let name = unsafe { Atom::from_raw(name) };
-            if name == atom!("none") {
-                Either::First(CounterStyleOrNone::None)
-            } else {
-                Either::First(CounterStyleOrNone::Name(CustomIdent(name)))
-            }
+            debug_assert_ne!(name, atom!("none"));
+            Either::First(CounterStyle::Name(CustomIdent(name)))
         } else {
             let anonymous =
                 unsafe { bindings::Gecko_CounterStyle_GetAnonymous(gecko_value).as_ref() }.unwrap();
@@ -113,7 +108,7 @@ impl CounterStyleOrNone {
                     .iter()
                     .map(|gecko_symbol| Symbol::String(gecko_symbol.to_string().into()))
                     .collect();
-                Either::First(CounterStyleOrNone::Symbols(symbol_type, Symbols(symbols)))
+                Either::First(CounterStyle::Symbols(symbol_type, Symbols(symbols)))
             }
         }
     }

components/style/properties/gecko.mako.rs

@@ -2199,10 +2199,15 @@ fn static_assert() {
     }
 
     pub fn set_list_style_type(&mut self, v: longhands::list_style_type::computed_value::T) {
+        use crate::gecko_bindings::bindings::Gecko_SetCounterStyleToName;
         use crate::gecko_bindings::bindings::Gecko_SetCounterStyleToString;
         use nsstring::{nsACString, nsCStr};
         use self::longhands::list_style_type::computed_value::T;
         match v {
+            T::None => unsafe {
+                Gecko_SetCounterStyleToName(&mut self.gecko.mCounterStyle,
+                                            atom!("none").into_addrefed());
+            }
             T::CounterStyle(s) => s.to_gecko_value(&mut self.gecko.mCounterStyle),
             T::String(s) => unsafe {
                 Gecko_SetCounterStyleToString(&mut self.gecko.mCounterStyle,
@@ -2224,9 +2229,19 @@ fn static_assert() {
     pub fn clone_list_style_type(&self) -> longhands::list_style_type::computed_value::T {
         use self::longhands::list_style_type::computed_value::T;
         use crate::values::Either;
-        use crate::values::generics::CounterStyleOrNone;
+        use crate::values::generics::CounterStyle;
+        use crate::gecko_bindings::bindings;
 
-        let result = CounterStyleOrNone::from_gecko_value(&self.gecko.mCounterStyle);
+        let name = unsafe {
+            bindings::Gecko_CounterStyle_GetName(&self.gecko.mCounterStyle)
+        };
+        if !name.is_null() {
+            let name = unsafe { Atom::from_raw(name) };
+            if name == atom!("none") {
+                return T::None;
+            }
+        }
+        let result = CounterStyle::from_gecko_value(&self.gecko.mCounterStyle);
         match result {
             Either::First(counter_style) => T::CounterStyle(counter_style),
             Either::Second(string) => T::String(string),
@@ -2573,7 +2588,7 @@ clip-path
     pub fn set_content(&mut self, v: longhands::content::computed_value::T) {
         use crate::values::CustomIdent;
         use crate::values::generics::counters::{Content, ContentItem};
-        use crate::values::generics::CounterStyleOrNone;
+        use crate::values::generics::CounterStyle;
         use crate::gecko_bindings::structs::nsStyleContentData;
         use crate::gecko_bindings::structs::nsStyleContentAttr;
         use crate::gecko_bindings::structs::StyleContentType;
@@ -2594,7 +2609,7 @@ clip-path
             content_type: StyleContentType,
             name: CustomIdent,
             sep: &str,
-            style: CounterStyleOrNone,
+            style: CounterStyle,
         ) {
             debug_assert!(content_type == StyleContentType::Counter ||
                           content_type == StyleContentType::Counters);
@@ -2724,7 +2739,7 @@ clip-path
         use crate::gecko_bindings::structs::StyleContentType;
         use crate::values::generics::counters::{Content, ContentItem};
         use crate::values::{CustomIdent, Either};
-        use crate::values::generics::CounterStyleOrNone;
+        use crate::values::generics::CounterStyle;
         use crate::values::specified::Attr;
 
         if self.gecko.mContents.is_empty() {
@@ -2769,7 +2784,7 @@ clip-path
                             Atom::from_raw(gecko_function.mIdent.mRawPtr)
                         });
                         let style =
-                            CounterStyleOrNone::from_gecko_value(&gecko_function.mCounterStyle);
+                            CounterStyle::from_gecko_value(&gecko_function.mCounterStyle);
                         let style = match style {
                             Either::First(counter_style) => counter_style,
                             Either::Second(_) =>

components/style/properties/shorthands/list.mako.rs

@@ -61,31 +61,23 @@
 
         let position = unwrap_or_initial!(list_style_position, position);
 
-        fn list_style_type_none() -> list_style_type::SpecifiedValue {
-            % if engine == "gecko":
-                use crate::values::generics::CounterStyleOrNone;
-                list_style_type::SpecifiedValue::CounterStyle(CounterStyleOrNone::None)
-            % else:
-                list_style_type::SpecifiedValue::None
-            % endif
-        }
-
         // If there are two `none`s, then we can't have a type or image; if there is one `none`,
         // then we can't have both a type *and* an image; if there is no `none` then we're fine as
         // long as we parsed something.
+        use self::list_style_type::SpecifiedValue as ListStyleType;
         match (any, nones, list_style_type, image) {
             (true, 2, None, None) => {
                 Ok(expanded! {
                     list_style_position: position,
                     list_style_image: ImageUrlOrNone::none(),
-                    list_style_type: list_style_type_none(),
+                    list_style_type: ListStyleType::None,
                 })
             }
             (true, 1, None, Some(image)) => {
                 Ok(expanded! {
                     list_style_position: position,
                     list_style_image: image,
-                    list_style_type: list_style_type_none(),
+                    list_style_type: ListStyleType::None,
                 })
             }
             (true, 1, Some(list_style_type), None) => {
@@ -99,7 +91,7 @@
                 Ok(expanded! {
                     list_style_position: position,
                     list_style_image: ImageUrlOrNone::none(),
-                    list_style_type: list_style_type_none(),
+                    list_style_type: ListStyleType::None,
                 })
             }
             (true, 0, list_style_type, image) => {

components/style/values/generics/counters.rs

@@ -7,7 +7,7 @@
 #[cfg(feature = "servo")]
 use crate::computed_values::list_style_type::T as ListStyleType;
 #[cfg(feature = "gecko")]
-use crate::values::generics::CounterStyleOrNone;
+use crate::values::generics::CounterStyle;
 #[cfg(feature = "gecko")]
 use crate::values::specified::Attr;
 use crate::values::CustomIdent;
@@ -127,7 +127,7 @@ impl<I> Counters<I> {
 type CounterStyleType = ListStyleType;
 
 #[cfg(feature = "gecko")]
-type CounterStyleType = CounterStyleOrNone;
+type CounterStyleType = CounterStyle;
 
 #[cfg(feature = "servo")]
 #[inline]
@@ -138,7 +138,7 @@ fn is_decimal(counter_type: &CounterStyleType) -> bool {
 #[cfg(feature = "gecko")]
 #[inline]
 fn is_decimal(counter_type: &CounterStyleType) -> bool {
-    *counter_type == CounterStyleOrNone::decimal()
+    *counter_type == CounterStyle::decimal()
 }
 
 /// The specified value for the `content` property.

components/style/values/generics/mod.rs

@@ -92,13 +92,10 @@ impl SymbolsType {
 
 /// <https://drafts.csswg.org/css-counter-styles/#typedef-counter-style>
 ///
-/// Since wherever <counter-style> is used, 'none' is a valid value as
-/// well, we combine them into one type to make code simpler.
+/// Note that 'none' is not a valid name.
 #[cfg_attr(feature = "gecko", derive(MallocSizeOf))]
 #[derive(Clone, Debug, Eq, PartialEq, ToComputedValue, ToCss, ToResolvedValue, ToShmem)]
-pub enum CounterStyleOrNone {
-    /// `none`
-    None,
+pub enum CounterStyle {
     /// `<counter-style-name>`
     Name(CustomIdent),
     /// `symbols()`
@@ -111,28 +108,25 @@ fn is_symbolic(symbols_type: &SymbolsType) -> bool {
     *symbols_type == SymbolsType::Symbolic
 }
 
-impl CounterStyleOrNone {
+impl CounterStyle {
     /// disc value
     pub fn disc() -> Self {
-        CounterStyleOrNone::Name(CustomIdent(atom!("disc")))
+        CounterStyle::Name(CustomIdent(atom!("disc")))
     }
 
     /// decimal value
     pub fn decimal() -> Self {
-        CounterStyleOrNone::Name(CustomIdent(atom!("decimal")))
+        CounterStyle::Name(CustomIdent(atom!("decimal")))
     }
 }
 
-impl Parse for CounterStyleOrNone {
+impl Parse for CounterStyle {
     fn parse<'i, 't>(
         context: &ParserContext,
         input: &mut Parser<'i, 't>,
     ) -> Result<Self, ParseError<'i>> {
         if let Ok(name) = input.try(|i| parse_counter_style_name(i)) {
-            return Ok(CounterStyleOrNone::Name(name));
-        }
-        if input.try(|i| i.expect_ident_matching("none")).is_ok() {
-            return Ok(CounterStyleOrNone::None);
+            return Ok(CounterStyle::Name(name));
         }
         input.expect_function_matching("symbols")?;
         input.parse_nested_block(|input| {
@@ -151,12 +145,12 @@ impl Parse for CounterStyleOrNone {
             if symbols.0.iter().any(|sym| !sym.is_allowed_in_symbols()) {
                 return Err(input.new_custom_error(StyleParseErrorKind::UnspecifiedError));
             }
-            Ok(CounterStyleOrNone::Symbols(symbols_type, symbols))
+            Ok(CounterStyle::Symbols(symbols_type, symbols))
         })
     }
 }
 
-impl SpecifiedValueInfo for CounterStyleOrNone {
+impl SpecifiedValueInfo for CounterStyle {
     fn collect_completion_keywords(f: KeywordsCollectFn) {
         // XXX The best approach for implementing this is probably
         // having a CounterStyleName type wrapping CustomIdent, and
@@ -165,7 +159,7 @@ impl SpecifiedValueInfo for CounterStyleOrNone {
         // approach here.
         macro_rules! predefined {
             ($($name:expr,)+) => {
-                f(&["none", "symbols", $($name,)+]);
+                f(&["symbols", $($name,)+]);
             }
         }
         include!("../../counter_style/predefined.rs");

components/style/values/specified/counters.rs

@@ -12,7 +12,7 @@ use crate::values::generics::counters::CounterIncrement as GenericCounterIncreme
 use crate::values::generics::counters::CounterPair;
 use crate::values::generics::counters::CounterSetOrReset as GenericCounterSetOrReset;
 #[cfg(feature = "gecko")]
-use crate::values::generics::CounterStyleOrNone;
+use crate::values::generics::CounterStyle;
 use crate::values::specified::url::SpecifiedImageUrl;
 #[cfg(feature = "gecko")]
 use crate::values::specified::Attr;
@@ -98,13 +98,13 @@ impl Content {
     }
 
     #[cfg(feature = "gecko")]
-    fn parse_counter_style(context: &ParserContext, input: &mut Parser) -> CounterStyleOrNone {
+    fn parse_counter_style(context: &ParserContext, input: &mut Parser) -> CounterStyle {
         input
             .try(|input| {
                 input.expect_comma()?;
-                CounterStyleOrNone::parse(context, input)
+                CounterStyle::parse(context, input)
             })
-            .unwrap_or(CounterStyleOrNone::decimal())
+            .unwrap_or(CounterStyle::decimal())
     }
 }
 

components/style/values/specified/list.rs

@@ -6,7 +6,7 @@
 
 use crate::parser::{Parse, ParserContext};
 #[cfg(feature = "gecko")]
-use crate::values::generics::CounterStyleOrNone;
+use crate::values::generics::CounterStyle;
 #[cfg(feature = "gecko")]
 use crate::values::CustomIdent;
 use cssparser::{Parser, Token};
@@ -27,8 +27,10 @@ use style_traits::{ParseError, StyleParseErrorKind};
     ToShmem,
 )]
 pub enum ListStyleType {
-    /// <counter-style> | none
-    CounterStyle(CounterStyleOrNone),
+    /// `none`
+    None,
+    /// <counter-style>
+    CounterStyle(CounterStyle),
     /// <string>
     String(String),
 }
@@ -38,7 +40,7 @@ impl ListStyleType {
     /// Initial specified value for `list-style-type`.
     #[inline]
     pub fn disc() -> Self {
-        ListStyleType::CounterStyle(CounterStyleOrNone::disc())
+        ListStyleType::CounterStyle(CounterStyle::disc())
     }
 
     /// Convert from gecko keyword to list-style-type.
@@ -50,10 +52,10 @@ impl ListStyleType {
         use crate::gecko_bindings::structs;
 
         if value == structs::NS_STYLE_LIST_STYLE_NONE {
-            return ListStyleType::CounterStyle(CounterStyleOrNone::None);
+            return ListStyleType::None;
         }
 
-        ListStyleType::CounterStyle(CounterStyleOrNone::Name(CustomIdent(match value {
+        ListStyleType::CounterStyle(CounterStyle::Name(CustomIdent(match value {
             structs::NS_STYLE_LIST_STYLE_DISC => atom!("disc"),
             structs::NS_STYLE_LIST_STYLE_CIRCLE => atom!("circle"),
             structs::NS_STYLE_LIST_STYLE_SQUARE => atom!("square"),
@@ -73,10 +75,12 @@ impl Parse for ListStyleType {
         context: &ParserContext,
         input: &mut Parser<'i, 't>,
     ) -> Result<Self, ParseError<'i>> {
-        if let Ok(style) = input.try(|i| CounterStyleOrNone::parse(context, i)) {
+        if let Ok(style) = input.try(|i| CounterStyle::parse(context, i)) {
             return Ok(ListStyleType::CounterStyle(style));
         }
-
+        if input.try(|i| i.expect_ident_matching("none")).is_ok() {
+            return Ok(ListStyleType::None);
+        }
         Ok(ListStyleType::String(
             input.expect_string()?.as_ref().to_owned(),
         ))