[3.8] bpo-36917: Add default implementation of ast.NodeVisitor.visit_Constant(). (GH-15490) (GH-15509)
It emits a deprecation warning and calls corresponding method
visit_Num(), visit_Str(), etc.
(cherry picked from commit c3ea41e9bf100a5396b851488c3efe208e5e2179)
diff --git a/Lib/ast.py b/Lib/ast.py
index ffeba17..da47825 100644
--- a/Lib/ast.py
+++ b/Lib/ast.py
@@ -360,6 +360,27 @@
elif isinstance(value, AST):
self.visit(value)
+ def visit_Constant(self, node):
+ value = node.value
+ type_name = _const_node_type_names.get(type(value))
+ if type_name is None:
+ for cls, name in _const_node_type_names.items():
+ if isinstance(value, cls):
+ type_name = name
+ break
+ if type_name is not None:
+ method = 'visit_' + type_name
+ try:
+ visitor = getattr(self, method)
+ except AttributeError:
+ pass
+ else:
+ import warnings
+ warnings.warn(f"{method} is deprecated; add visit_Constant",
+ PendingDeprecationWarning, 2)
+ return visitor(node)
+ return self.generic_visit(node)
+
class NodeTransformer(NodeVisitor):
"""
@@ -487,3 +508,13 @@
_const_types_not = {
Num: (bool,),
}
+_const_node_type_names = {
+ bool: 'NameConstant', # should be before int
+ type(None): 'NameConstant',
+ int: 'Num',
+ float: 'Num',
+ complex: 'Num',
+ str: 'Str',
+ bytes: 'Bytes',
+ type(...): 'Ellipsis',
+}