Add support for positional-only arguments

cpython commit: 8c77b8cb9188165a123f2512026e3629bf03dc9b

Author: progval

CHANGELOG.md

@@ -2,9 +2,13 @@
 
 work in progress
 
+Support for 3.8 syntax
+
 Breaking changes:
 
 * Added `Expression::Await` variant
+* Added `Expression::Named` variant
+* Changed TypedArgsList and UntypedArgsList to add `posonly_args` field, and rename `positional_args` to `args`
 
 Other changes
 

README.md

@@ -1,5 +1,5 @@
 # rust-python-parser
 A Python parser for Rust libraries and programs.
 
-Currently supports Python 3.7's syntax (and Python 3.8 up to
-[2018-09-22](http://github.com/python/cpython/commit/fd97d1f1af910a6222ea12aec42c456b64f9aee4)).
+Currently supports Python 3.8's syntax (except type comments,
+which are ignored like regular comments)

src/ast.rs

@@ -45,7 +45,8 @@ impl<T> Default for StarParams<T> {
 /// The list of parameters of a function definition.
 #[derive(Clone, Debug, PartialEq, Default)]
 pub struct TypedArgsList {
-    pub positional_args: Vec<(Name, Option<Expression>, Option<Expression>)>,
+    pub posonly_args: Vec<(Name, Option<Expression>, Option<Expression>)>,
+    pub args: Vec<(Name, Option<Expression>, Option<Expression>)>,
     pub star_args: StarParams<(Name, Option<Expression>)>,
     pub keyword_args: Vec<(Name, Option<Expression>, Option<Expression>)>,
     pub star_kwargs: Option<(Name, Option<Expression>)>,
@@ -54,7 +55,8 @@ pub struct TypedArgsList {
 /// The list of parameters of a lambda definition.
 #[derive(Clone, Debug, PartialEq, Default)]
 pub struct UntypedArgsList {
-    pub positional_args: Vec<(Name, Option<Expression>)>,
+    pub posonly_args: Vec<(Name, Option<Expression>)>,
+    pub args: Vec<(Name, Option<Expression>)>,
     pub star_args: StarParams<Name>,
     pub keyword_args: Vec<(Name, Option<Expression>)>,
     pub star_kwargs: Option<Name>,