bpo-32892: Use ast.Constant instead of specific constant AST types. (GH-9445)
diff --git a/Lib/ast.py b/Lib/ast.py
index bfe346b..de3df14 100644
--- a/Lib/ast.py
+++ b/Lib/ast.py
@@ -48,10 +48,8 @@
node_or_string = node_or_string.body
def _convert_num(node):
if isinstance(node, Constant):
- if isinstance(node.value, (int, float, complex)):
+ if type(node.value) in (int, float, complex):
return node.value
- elif isinstance(node, Num):
- return node.n
raise ValueError('malformed node or string: ' + repr(node))
def _convert_signed_num(node):
if isinstance(node, UnaryOp) and isinstance(node.op, (UAdd, USub)):
@@ -64,10 +62,6 @@
def _convert(node):
if isinstance(node, Constant):
return node.value
- elif isinstance(node, (Str, Bytes)):
- return node.s
- elif isinstance(node, Num):
- return node.n
elif isinstance(node, Tuple):
return tuple(map(_convert, node.elts))
elif isinstance(node, List):
@@ -77,8 +71,6 @@
elif isinstance(node, Dict):
return dict(zip(map(_convert, node.keys),
map(_convert, node.values)))
- elif isinstance(node, NameConstant):
- return node.value
elif isinstance(node, BinOp) and isinstance(node.op, (Add, Sub)):
left = _convert_signed_num(node.left)
right = _convert_num(node.right)
@@ -329,3 +321,66 @@
else:
setattr(node, field, new_node)
return node
+
+
+# The following code is for backward compatibility.
+# It will be removed in future.
+
+def _getter(self):
+ return self.value
+
+def _setter(self, value):
+ self.value = value
+
+Constant.n = property(_getter, _setter)
+Constant.s = property(_getter, _setter)
+
+class _ABC(type):
+
+ def __instancecheck__(cls, inst):
+ if not isinstance(inst, Constant):
+ return False
+ if cls in _const_types:
+ try:
+ value = inst.value
+ except AttributeError:
+ return False
+ else:
+ return type(value) in _const_types[cls]
+ return type.__instancecheck__(cls, inst)
+
+def _new(cls, *args, **kwargs):
+ if cls in _const_types:
+ return Constant(*args, **kwargs)
+ return Constant.__new__(cls, *args, **kwargs)
+
+class Num(Constant, metaclass=_ABC):
+ _fields = ('n',)
+ __new__ = _new
+
+class Str(Constant, metaclass=_ABC):
+ _fields = ('s',)
+ __new__ = _new
+
+class Bytes(Constant, metaclass=_ABC):
+ _fields = ('s',)
+ __new__ = _new
+
+class NameConstant(Constant, metaclass=_ABC):
+ __new__ = _new
+
+class Ellipsis(Constant, metaclass=_ABC):
+ _fields = ()
+
+ def __new__(cls, *args, **kwargs):
+ if cls is Ellipsis:
+ return Constant(..., *args, **kwargs)
+ return Constant.__new__(cls, *args, **kwargs)
+
+_const_types = {
+ Num: (int, float, complex),
+ Str: (str,),
+ Bytes: (bytes,),
+ NameConstant: (type(None), bool),
+ Ellipsis: (type(...),),
+}