lexer: resolve small regex ambiguity

lexer/src/lib.rs

@@ -139,7 +139,7 @@ pub enum Token<'a> {
     Minus,
     #[token("*", accept_expression)]
     Star,
-    #[token("/", parse_regex_or_slash)]
+    #[token("/", parse_regex_or_op)]
     Slash,
     /// Not generated by Logos directly.
     Regex(Slice<'a>),
@@ -160,7 +160,7 @@ pub enum Token<'a> {
     MinusAssign,
     #[token("*=", accept_expression)]
     StarAssign,
-    #[token("/=", accept_expression)]
+    /// Not generated by Logos directly.
     SlashAssign,
     #[token("%=", accept_expression)]
     PercentAssign,
@@ -313,7 +313,7 @@ fn parse_string<'a>(lex: &mut logos::Lexer<'a, Token<'a>>) -> Result<Slice<'a>>
     parse_content::<false, '"'>(lex)
 }
 
-fn parse_regex_or_slash<'a>(lex: &mut logos::Lexer<'a, Token<'a>>) -> Result<Token<'a>> {
+fn parse_regex_or_op<'a>(lex: &mut logos::Lexer<'a, Token<'a>>) -> Result<Token<'a>> {
     match lex.extras.ctx {
         Context::AcceptExpression => {
             accept_operator(lex);
@@ -321,7 +321,12 @@ fn parse_regex_or_slash<'a>(lex: &mut logos::Lexer<'a, Token<'a>>) -> Result<Tok
         }
         Context::AcceptOperator => {
             accept_expression(lex);
-            Ok(Token::Slash)
+            if lex.remainder().first() == Some(&b'=') {
+                lex.bump(1);
+                Ok(Token::SlashAssign)
+            } else {
+                Ok(Token::Slash)
+            }
         }
     }
 }