Merge pull request #237 from darki73/feat/pep695-type-params

PEP 695 type parameter syntax for Python 3.12+

Author: davidhalter

conftest.py

@@ -145,3 +145,15 @@ def works_ge_py38(each_version):
 def works_ge_py39(each_version):
     version_info = parse_version_string(each_version)
     return Checker(each_version, version_info >= (3, 9))
+
+
+@pytest.fixture
+def works_ge_py312(each_version):
+    version_info = parse_version_string(each_version)
+    return Checker(each_version, version_info >= (3, 12))
+
+
+@pytest.fixture
+def works_ge_py313(each_version):
+    version_info = parse_version_string(each_version)
+    return Checker(each_version, version_info >= (3, 13))

parso/python/grammar312.txt

@@ -17,7 +17,11 @@ decorators: decorator+
 decorated: decorators (classdef | funcdef | async_funcdef)
 
 async_funcdef: 'async' funcdef
-funcdef: 'def' NAME parameters ['->' test] ':' suite
+funcdef: 'def' NAME [type_params] parameters ['->' test] ':' suite
+
+type_params: '[' type_param (',' type_param)* [','] ']'
+type_param: NAME [type_param_bound] | '*' NAME | '**' NAME
+type_param_bound: ':' test
 
 parameters: '(' [typedargslist] ')'
 typedargslist: (
@@ -131,7 +135,7 @@ dictorsetmaker: ( ((test ':' test | '**' expr)
                   ((test [':=' test] | star_expr)
                    (comp_for | (',' (test [':=' test] | star_expr))* [','])) )
 
-classdef: 'class' NAME ['(' [arglist] ')'] ':' suite
+classdef: 'class' NAME [type_params] ['(' [arglist] ')'] ':' suite
 
 arglist: argument (',' argument)*  [',']
 

parso/python/grammar313.txt

@@ -17,7 +17,12 @@ decorators: decorator+
 decorated: decorators (classdef | funcdef | async_funcdef)
 
 async_funcdef: 'async' funcdef
-funcdef: 'def' NAME parameters ['->' test] ':' suite
+funcdef: 'def' NAME [type_params] parameters ['->' test] ':' suite
+
+type_params: '[' type_param (',' type_param)* [','] ']'
+type_param: NAME [type_param_bound] [type_param_default] | '*' NAME [type_param_default] | '**' NAME [type_param_default]
+type_param_bound: ':' test
+type_param_default: '=' test
 
 parameters: '(' [typedargslist] ')'
 typedargslist: (
@@ -131,7 +136,7 @@ dictorsetmaker: ( ((test ':' test | '**' expr)
                   ((test [':=' test] | star_expr)
                    (comp_for | (',' (test [':=' test] | star_expr))* [','])) )
 
-classdef: 'class' NAME ['(' [arglist] ')'] ':' suite
+classdef: 'class' NAME [type_params] ['(' [arglist] ')'] ':' suite
 
 arglist: argument (',' argument)*  [',']
 

parso/python/grammar314.txt

@@ -17,7 +17,12 @@ decorators: decorator+
 decorated: decorators (classdef | funcdef | async_funcdef)
 
 async_funcdef: 'async' funcdef
-funcdef: 'def' NAME parameters ['->' test] ':' suite
+funcdef: 'def' NAME [type_params] parameters ['->' test] ':' suite
+
+type_params: '[' type_param (',' type_param)* [','] ']'
+type_param: NAME [type_param_bound] [type_param_default] | '*' NAME [type_param_default] | '**' NAME [type_param_default]
+type_param_bound: ':' test
+type_param_default: '=' test
 
 parameters: '(' [typedargslist] ')'
 typedargslist: (
@@ -131,7 +136,7 @@ dictorsetmaker: ( ((test ':' test | '**' expr)
                   ((test [':=' test] | star_expr)
                    (comp_for | (',' (test [':=' test] | star_expr))* [','])) )
 
-classdef: 'class' NAME ['(' [arglist] ')'] ':' suite
+classdef: 'class' NAME [type_params] ['(' [arglist] ')'] ':' suite
 
 arglist: argument (',' argument)*  [',']
 

parso/python/tree.py

@@ -479,13 +479,13 @@ def get_super_arglist(self):
         Returns the `arglist` node that defines the super classes. It returns
         None if there are no arguments.
         """
-        if self.children[2] != '(':  # Has no parentheses
-            return None
-        else:
-            if self.children[3] == ')':  # Empty parentheses
-                return None
-            else:
-                return self.children[3]
+        for i, child in enumerate(self.children):
+            if child == '(':
+                next_child = self.children[i + 1]
+                if next_child == ')':
+                    return None
+                return next_child
+        return None
 
 
 def _create_params(parent, argslist_list):
@@ -552,15 +552,21 @@ class Function(ClassOrFunc):
 
     def __init__(self, children):
         super().__init__(children)
-        parameters = self.children[2]  # After `def foo`
+        parameters = self._find_parameters()
         parameters_children = parameters.children[1:-1]
-        # If input parameters list already has Param objects, keep it as is;
-        # otherwise, convert it to a list of Param objects.
         if not any(isinstance(child, Param) for child in parameters_children):
-            parameters.children[1:-1] = _create_params(parameters, parameters_children)
+            parameters.children[1:-1] = _create_params(
+                parameters, parameters_children
+            )
+
+    def _find_parameters(self):
+        for child in self.children:
+            if child.type == 'parameters':
+                return child
+        raise Exception("A function should always have parameters")
 
     def _get_param_nodes(self):
-        return self.children[2].children
+        return self._find_parameters().children
 
     def get_params(self):
         """
@@ -633,13 +639,10 @@ def annotation(self):
         """
         Returns the test node after `->` or `None` if there is no annotation.
         """
-        try:
-            if self.children[3] == "->":
-                return self.children[4]
-            assert self.children[3] == ":"
-            return None
-        except IndexError:
-            return None
+        for i, child in enumerate(self.children):
+            if child == '->':
+                return self.children[i + 1]
+        return None
 
 
 class Lambda(Function):

test/test_parser.py

@@ -206,3 +206,64 @@ def test_positional_only_arguments(works_ge_py38, param_code):
 )
 def test_decorator_expression(works_ge_py39, expression):
     works_ge_py39.parse("@%s\ndef x(): pass" % expression)
+
+
+@pytest.mark.parametrize(
+    'code', [
+        'class Foo[T]: pass',
+        'class Foo[T: str]: pass',
+        'class Foo[T, U]: pass',
+        'class Foo[T: str, U: int]: pass',
+        'class Foo[T](Base): pass',
+        'class Foo[T: str](Base, Mixin): pass',
+        'class Foo[*Ts]: pass',
+        'class Foo[**P]: pass',
+    ]
+)
+def test_pep695_generic_class(works_ge_py312, code):
+    works_ge_py312.parse(code)
+
+
+@pytest.mark.parametrize(
+    'code', [
+        'def foo[T](x: T) -> T: pass',
+        'def foo[T: int](x: T) -> T: pass',
+        'def foo[T, U](x: T, y: U): pass',
+        'def foo[*Ts](*args): pass',
+        'def foo[**P](*args): pass',
+    ]
+)
+def test_pep695_generic_function(works_ge_py312, code):
+    works_ge_py312.parse(code)
+
+
+def test_pep695_class_get_super_arglist(works_ge_py312):
+    module = works_ge_py312.parse('class Foo[T](Bar, Baz): pass')
+    if module is None:
+        return
+    classdef = module.children[0]
+    arglist = classdef.get_super_arglist()
+    assert arglist is not None
+    assert 'Bar' in arglist.get_code()
+    assert 'Baz' in arglist.get_code()
+
+
+def test_pep695_class_no_bases(works_ge_py312):
+    module = works_ge_py312.parse('class Foo[T]: pass')
+    if module is None:
+        return
+    classdef = module.children[0]
+    assert classdef.get_super_arglist() is None
+
+
+@pytest.mark.parametrize(
+    'code', [
+        'class Foo[T = int]: pass',
+        'class Foo[T: str = "default"]: pass',
+        'class Foo[*Ts = tuple[int, ...]]: pass',
+        'class Foo[**P = None]: pass',
+        'def foo[T = int](x: T) -> T: pass',
+    ]
+)
+def test_pep696_type_param_defaults(works_ge_py313, code):
+    works_ge_py313.parse(code)