feat(css/ast): Add types for An+b syntax (#2759)

crates/swc_css_ast/src/selector.rs

@@ -1,6 +1,7 @@
 use crate::{Ident, Str, Tokens};
 use is_macro::Is;
 use string_enum::StringEnum;
+use swc_atoms::JsWord;
 use swc_common::{ast_node, EqIgnoreSpan, Span};
 
 #[ast_node("SelectorList")]
@@ -130,12 +131,48 @@ pub struct AttrSelector {
     pub modifier: Option<char>,
 }
 
+#[ast_node]
+#[derive(Is)]
+pub enum PseudoSelectorChildren {
+    #[tag("Nth")]
+    Nth(Nth),
+
+    #[tag("Tokens")]
+    Tokens(Tokens),
+}
+
+#[ast_node("Nth")]
+pub struct Nth {
+    pub span: Span,
+    pub nth: NthValue,
+    pub selector_list: Option<SelectorList>,
+}
+
+#[ast_node("AnPlusB")]
+pub struct AnPlusB {
+    pub span: Span,
+    pub a: Option<i32>,
+    pub a_raw: Option<JsWord>,
+    pub b: Option<i32>,
+    pub b_raw: Option<JsWord>,
+}
+
+#[ast_node]
+#[derive(Is)]
+pub enum NthValue {
+    #[tag("AnPlusB")]
+    AnPlusB(AnPlusB),
+
+    #[tag("Ident")]
+    Ident(Ident),
+}
+
 #[ast_node("PseudoSelector")]
 pub struct PseudoSelector {
     pub span: Span,
     pub is_element: bool,
     pub name: Ident,
-    pub args: Tokens,
+    pub children: Option<PseudoSelectorChildren>,
 }
 
 #[ast_node("IdSelector")]

crates/swc_css_codegen/src/lib.rs

@@ -788,18 +788,56 @@ where
         punct!(self, "]");
     }
 
+    #[emitter]
+    fn emit_nth(&mut self, n: &Nth) -> Result {
+        emit!(self, n.nth);
+
+        if n.selector_list.is_some() {
+            emit!(self, n.selector_list);
+        }
+    }
+
+    #[emitter]
+    fn emit_an_plus_b(&mut self, n: &AnPlusB) -> Result {
+        if let Some(a_raw) = &n.a_raw {
+            self.wr.write_raw(Some(n.span), a_raw)?;
+            punct!(self, "n");
+        }
+
+        if let Some(b_raw) = &n.b_raw {
+            self.wr.write_raw(Some(n.span), b_raw)?;
+        }
+    }
+
+    #[emitter]
+    fn emit_nth_value(&mut self, n: &NthValue) -> Result {
+        match n {
+            NthValue::AnPlusB(n) => emit!(self, n),
+            NthValue::Ident(n) => emit!(self, n),
+        }
+    }
+
+    #[emitter]
+    fn emit_pseudo_selector_children(&mut self, n: &PseudoSelectorChildren) -> Result {
+        match n {
+            PseudoSelectorChildren::Nth(n) => emit!(self, n),
+            PseudoSelectorChildren::Tokens(n) => emit!(self, n),
+        }
+    }
+
     #[emitter]
     fn emit_pseudo_selector(&mut self, n: &PseudoSelector) -> Result {
         punct!(self, ":");
+
         if n.is_element {
             punct!(self, ":");
         }
 
         emit!(self, n.name);
 
-        if !n.args.tokens.is_empty() {
+        if n.children.is_some() {
             punct!(self, "(");
-            emit!(self, n.args);
+            emit!(self, n.children);
             punct!(self, ")");
         }
     }

crates/swc_css_parser/src/error.rs

@@ -49,6 +49,7 @@ impl Error {
             ErrorKind::InvalidMediaQuery => "Invalid media query".into(),
             ErrorKind::UnknownAtRuleNotTerminated => "Unknown @rule is not terminated".into(),
             ErrorKind::InvalidDeclarationValue => "Expected a property value".into(),
+            ErrorKind::InvalidAnPlusBMicrosyntax => "Invalid An+B microsyntax".into(),
         };
         handler.struct_span_err(self.inner.0, &msg)
     }
@@ -80,6 +81,7 @@ pub enum ErrorKind {
     InvalidSupportQuery,
     InvalidKeyframeSelector,
     InvalidMediaQuery,
+    InvalidAnPlusBMicrosyntax,
 
     UnknownAtRuleNotTerminated,
 }