feat(css/parser): parse highlight

crates/swc_css_ast/src/selector.rs

@@ -368,4 +368,22 @@ pub enum PseudoElementSelectorChildren {
     Ident(Ident),
     #[tag("CompoundSelector")]
     CompoundSelector(CompoundSelector),
+    #[tag("CustomHighlightName")]
+    CustomHighlightName(CustomHighlightName),
+}
+
+#[ast_node("CustomHighlightName")]
+#[derive(Eq, Hash)]
+pub struct CustomHighlightName {
+    pub span: Span,
+    #[cfg_attr(feature = "rkyv", with(swc_atoms::EncodeJsWord))]
+    pub value: JsWord,
+    #[cfg_attr(feature = "rkyv", with(swc_atoms::EncodeJsWord))]
+    pub raw: Option<JsWord>,
+}
+
+impl EqIgnoreSpan for CustomHighlightName {
+    fn eq_ignore_span(&self, other: &Self) -> bool {
+        self.value == other.value
+    }
 }

crates/swc_css_codegen/src/lib.rs

@@ -1321,6 +1321,21 @@ where
         }
     }
 
+    #[emitter]
+    fn emit_custom_highlight_name(&mut self, n: &CustomHighlightName) -> Result {
+        if self.config.minify {
+            let serialized = serialize_ident(&n.value, n.raw.as_deref(), true);
+
+            write_raw!(self, n.span, &serialized);
+        } else if let Some(raw) = &n.raw {
+            write_raw!(self, n.span, raw);
+        } else {
+            let serialized = serialize_ident(&n.value, n.raw.as_deref(), true);
+
+            write_raw!(self, n.span, &serialized);
+        }
+    }
+
     #[emitter]
     fn emit_custom_ident(&mut self, n: &CustomIdent) -> Result {
         if self.config.minify {
@@ -2350,6 +2365,7 @@ where
             PseudoElementSelectorChildren::PreservedToken(n) => emit!(self, n),
             PseudoElementSelectorChildren::Ident(n) => emit!(self, n),
             PseudoElementSelectorChildren::CompoundSelector(n) => emit!(self, n),
+            PseudoElementSelectorChildren::CustomHighlightName(n) => emit!(self, n),
         }
     }
 

crates/swc_css_parser/src/parser/selector/mod.rs

@@ -1091,6 +1091,17 @@ where
 
                             self.input.skip_ws();
                         }
+                        "highlight" => {
+                            self.input.skip_ws();
+
+                            let custom_highlight_name = self.parse()?;
+
+                            children.push(PseudoElementSelectorChildren::CustomHighlightName(
+                                custom_highlight_name,
+                            ));
+
+                            self.input.skip_ws();
+                        }
                         _ => {
                             return Err(Error::new(span, ErrorKind::Ignore));
                         }
@@ -1376,3 +1387,27 @@ where
         }
     }
 }
+
+impl<I> Parse<CustomHighlightName> for Parser<I>
+where
+    I: ParserInput,
+{
+    fn parse(&mut self) -> PResult<CustomHighlightName> {
+        let span = self.input.cur_span();
+
+        if !is!(self, Ident) {
+            return Err(Error::new(span, ErrorKind::Expected("ident token")));
+        }
+
+        match bump!(self) {
+            Token::Ident { value, raw } => Ok(CustomHighlightName {
+                span,
+                value,
+                raw: Some(raw),
+            }),
+            _ => {
+                unreachable!()
+            }
+        }
+    }
+}

crates/swc_css_parser/tests/fixture/selector/pseudo-element/highlight/input.css

@@ -0,0 +1,16 @@
+::highlight(sample) {
+    background-color: rgba(0, 0, 255, 0.3);
+}
+
+:root::highlight(example-highlight) {
+    background-color: yellow;
+    color: blue;
+}
+
+div::highlight(bar) {
+    color: red;
+}
+
+div::highlight(foo) {
+    color: green;
+}