📝 Add support for positional-only parameters

dflook · dflook · commit 641b495455e3 · 2019-10-26T15:12:26.000+01:00
See https://www.python.org/dev/peps/pep-0570/
diff --git a/src/python_minifier/expression_printer.py b/src/python_minifier/expression_printer.py
@@ -586,8 +586,10 @@ def visit_Lambda(self, node):
     def visit_arguments(self, node):
         first = True
 
-        count_no_defaults = len(node.args) - len(node.defaults)
-        for i, arg in enumerate(node.args):
+        args = getattr(node, 'posonlyargs', []) + node.args
+
+        count_no_defaults = len(args) - len(node.defaults)
+        for i, arg in enumerate(args):
             if not first:
                 self.code += ','
             else:
@@ -600,6 +602,9 @@ def visit_arguments(self, node):
                 self.code += '='
                 self._expression(node.defaults[i - count_no_defaults])
 
+            if hasattr(node, 'posonlyargs') and node.posonlyargs and i + 1 == len(node.posonlyargs):
+                self.code += ',/'
+
         if node.vararg:
             if not first:
                 self.code += ','
diff --git a/src/python_minifier/rename/mapper.py b/src/python_minifier/rename/mapper.py
@@ -11,7 +11,7 @@ def add_parent_to_arguments(arguments, func):
     arguments.parent = func
     arguments.namespace = func
 
-    for arg in arguments.args:
+    for arg in getattr(arguments, 'posonlyargs', []) + arguments.args:
         add_parent(arg, arguments, func)
         if hasattr(arg, 'annotation') and arg.annotation is not None:
             add_parent(arg.annotation, arguments, func.namespace)
diff --git a/src/python_minifier/rename/util.py b/src/python_minifier/rename/util.py
@@ -53,6 +53,8 @@ def arg_rename_in_place(node):
     can be safely renamed. Comprehension arguments are not accessible from outside, so
     can be renamed.
 
+    If the argument is positional-only, it can be safely renamed
+
     Other arguments may be referenced by the caller as keyword arguments, so should not be
     renamed in place. The name assigner may still decide to bind the argument to a new name
     inside the function namespace.
@@ -85,6 +87,9 @@ def arg_rename_in_place(node):
         # starargs
         return True
 
+    if hasattr(func.args, 'posonlyargs') and node in func.args.posonlyargs:
+        return True
+
     return False
 
 
diff --git a/test/test_posargs.py b/test/test_posargs.py
@@ -0,0 +1,33 @@
+import ast
+import sys
+import pytest
+from python_minifier import unparse
+from python_minifier.ast_compare import compare_ast
+
+def test_pep():
+    if sys.version_info < (3, 8):
+        pytest.skip('No Assignment expressions in python < 3.8')
+
+    source = '''
+def name(p1, p2, /, p_or_kw, *, kw): pass
+def name(p1, p2=None, /, p_or_kw=None, *, kw): pass
+def name(p1, p2=None, /, *, kw): pass
+def name(p1, p2=None, /): pass
+def name(p1, p2, /, p_or_kw): pass
+def name(p1, p2, /): pass
+def name(p_or_kw, *, kw): pass
+def name(*, kw): pass
+
+def standard_arg(arg):
+    print(arg)
+def pos_only_arg(arg, /):
+    print(arg)
+def kwd_only_arg(*, arg):
+    print(arg)
+def combined_example(pos_only, /, standard, *, kwd_only):
+    print(pos_only, standard, kwd_only)
+'''
+
+    expected_ast = ast.parse(source)
+    actual_ast = unparse(expected_ast)
+    compare_ast(expected_ast, ast.parse(actual_ast))
