fix(css/parser): Add more error recovery (#6240)

crates/swc_css_parser/src/lexer/mod.rs

@@ -1,4 +1,4 @@
-use std::{cell::RefCell, char::REPLACEMENT_CHARACTER, mem::take, rc::Rc};
+use std::{cell::RefCell, char::REPLACEMENT_CHARACTER, rc::Rc};
 
 use swc_atoms::{js_word, JsWord};
 use swc_common::{input::Input, BytePos, Span};
@@ -11,7 +11,7 @@ use crate::{
 
 pub(crate) type LexResult<T> = Result<T, ErrorKind>;
 
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub struct Lexer<I>
 where
     I: Input,
@@ -27,7 +27,7 @@ where
     raw_buf: Rc<RefCell<String>>,
     sub_buf: Rc<RefCell<String>>,
     sub_raw_buf: Rc<RefCell<String>>,
-    errors: Vec<Error>,
+    errors: Rc<RefCell<Vec<Error>>>,
 }
 
 impl<I> Lexer<I>
@@ -48,7 +48,7 @@ where
             raw_buf: Rc::new(RefCell::new(String::with_capacity(256))),
             sub_buf: Rc::new(RefCell::new(String::with_capacity(32))),
             sub_raw_buf: Rc::new(RefCell::new(String::with_capacity(32))),
-            errors: vec![],
+            errors: Default::default(),
         }
     }
 
@@ -155,7 +155,7 @@ where
     }
 
     fn take_errors(&mut self) -> Vec<Error> {
-        take(&mut self.errors)
+        self.errors.take()
     }
 
     fn skip_ws(&mut self) -> Option<BytePos> {
@@ -220,7 +220,7 @@ where
 
     #[cold]
     fn emit_error(&mut self, kind: ErrorKind) {
-        self.errors.push(Error::new(
+        self.errors.borrow_mut().push(Error::new(
             Span::new(self.cur_pos, self.input.cur_pos(), Default::default()),
             kind,
         ));
@@ -510,6 +510,7 @@ where
                             let span = Span::new(self.start_pos, end, Default::default());
 
                             self.errors
+                                .borrow_mut()
                                 .push(Error::new(span, ErrorKind::UnterminatedBlockComment));
 
                             return;

crates/swc_css_parser/src/parser/input.rs

@@ -7,7 +7,7 @@ use swc_css_ast::{ComponentValue, ListOfComponentValues, Token, TokenAndSpan};
 use super::PResult;
 use crate::error::{Error, ErrorKind};
 
-pub trait ParserInput: Iterator<Item = TokenAndSpan> {
+pub trait ParserInput: Clone + Iterator<Item = TokenAndSpan> {
     type State: Debug;
 
     fn start_pos(&mut self) -> BytePos;
@@ -22,7 +22,7 @@ pub trait ParserInput: Iterator<Item = TokenAndSpan> {
     fn skip_ws(&mut self) -> Option<BytePos>;
 }
 
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub(super) struct Buffer<I>
 where
     I: ParserInput,
@@ -184,7 +184,7 @@ pub struct TokensState {
     idx: usize,
 }
 
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub struct TokensInput<'a> {
     tokens: &'a Tokens,
     idx: usize,
@@ -272,7 +272,7 @@ pub struct ListOfComponentValuesState {
     balance_stack: Vec<BalanceToken>,
 }
 
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub struct ListOfComponentValuesInput<'a> {
     list: &'a ListOfComponentValues,
     idx: Vec<usize>,

crates/swc_css_parser/src/parser/mod.rs

@@ -78,7 +78,7 @@ struct Ctx {
     is_trying_legacy_nesting: bool,
 }
 
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub struct Parser<I>
 where
     I: ParserInput,

crates/swc_css_parser/src/parser/util.rs

@@ -31,6 +31,21 @@ where
         self.parse()
     }
 
+    pub(super) fn try_parse<Ret>(
+        &mut self,
+        op: impl FnOnce(&mut Parser<I>) -> PResult<Ret>,
+    ) -> Option<Ret> {
+        let mut parser = self.clone();
+
+        match op(&mut parser) {
+            Ok(v) => {
+                *self = parser;
+                Some(v)
+            }
+            Err(..) => None,
+        }
+    }
+
     pub(super) fn create_locv(&self, children: Vec<ComponentValue>) -> ListOfComponentValues {
         let span = match (children.first(), children.last()) {
             (Some(first), Some(last)) => {

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

@@ -1273,12 +1273,29 @@ where
                     break;
                 }
 
-                let ctx = Ctx {
-                    block_contents_grammar: BlockContentsGrammar::DeclarationValue,
-                    ..self.ctx
+                let value = match self.try_parse(|p| {
+                    let ctx = Ctx {
+                        block_contents_grammar: BlockContentsGrammar::DeclarationValue,
+                        ..p.ctx
+                    };
+
+                    p.with_ctx(ctx).parse_as::<ComponentValue>()
+                }) {
+                    Some(v) => v,
+                    None => {
+                        if is_one_of!(self, ";", ":") {
+                            let tok = self.input.bump().unwrap();
+                            ComponentValue::PreservedToken(tok)
+                        } else {
+                            return Err(Error::new(
+                                self.input.cur_span(),
+                                ErrorKind::Expected("Declaration value"),
+                            ));
+                        }
+                    }
                 };
 
-                values.push(self.with_ctx(ctx).parse_as::<ComponentValue>()?);
+                values.push(value);
             },
         };
 

crates/swc_css_parser/tests/fixture/only/1/input.css

@@ -0,0 +1,5 @@
+@media screen and(-webkit-min-device-pixel-ratio:0) {
+    .gradientWrapper {
+      -chrome-: only(; z-index: 10;);
+    }
+}