Add namedexpr (aka walrus operator) in argument position.

cpython commit: 8f59ee01be3d83d5513a9a3f654a237d77d80d9a

src/expressions.rs

@@ -554,6 +554,7 @@ impl<ANS: AreNewlinesSpaces> ExpressionParser<ANS> {
  // arglist: argument (',' argument)* [',']
 
  // argument: ( test [comp_for] |
+ // test ':=' test |
  // test '=' test |
  // '**' test |
  // '*' test )
@@ -563,6 +564,12 @@ impl<ANS: AreNewlinesSpaces> ExpressionParser<ANS> {
  alt!(
  preceded!(tag!("**"), call!(Self::test)) => { |kwargs: Box<_>| Argument::Kwargs(*kwargs) }
  | preceded!(char!('*'), call!(Self::test)) => { |args: Box<_>| Argument::Starargs(*args) }
+ | do_parse!(
+ name: call!(Self::test) >>
+ value: preceded!(tag!(":="), call!(Self::test)) >> (
+ Argument::Positional(Expression::Named(name, value))
+ )
+ )
  | do_parse!(
  name: name >> // According to the grammar, this should be a 'test', but cpython actually refuses it (for good reasons)
  value: preceded!(char!('='), call!(Self::test)) >> (
@@ -1175,6 +1182,24 @@ mod tests {
  );
  }
 
+ #[test]
+ fn test_call_positional_namedexpr() {
+ let atom_expr = ExpressionParser::<NewlinesAreNotSpaces>::atom_expr;
+ assert_parse_eq(
+ atom_expr(make_strspan("foo(bar := baz)")),
+ Ok((
+ make_strspan(""),
+ Box::new(Expression::Call(
+ Box::new(Expression::Name("foo".to_string())),
+ vec![Argument::Positional(Expression::Named(
+ Box::new(Expression::Name("bar".to_string())),
+ Box::new(Expression::Name("baz".to_string())),
+ ))],
+ )),
+ )),
+ );
+ }
+
  #[test]
  fn test_call_positional() {
  let atom_expr = ExpressionParser::<NewlinesAreNotSpaces>::atom_expr;