Add ast.Constant
Issue #26146: Add a new kind of AST node: ast.Constant. It can be used by
external AST optimizers, but the compiler does not emit directly such node.
An optimizer can replace the following AST nodes with ast.Constant:
* ast.NameConstant: None, False, True
* ast.Num: int, float, complex
* ast.Str: str
* ast.Bytes: bytes
* ast.Tuple if items are constants too: tuple
* frozenset
Update code to accept ast.Constant instead of ast.Num and/or ast.Str:
* compiler
* docstrings
* ast.literal_eval()
* Tools/parser/unparse.py
diff --git a/Parser/Python.asdl b/Parser/Python.asdl
index 22775c6..aaddf61 100644
--- a/Parser/Python.asdl
+++ b/Parser/Python.asdl
@@ -1,4 +1,8 @@
--- ASDL's six builtin types are identifier, int, string, bytes, object, singleton
+-- ASDL's 7 builtin types are:
+-- identifier, int, string, bytes, object, singleton, constant
+--
+-- singleton: None, True or False
+-- constant can be None, whereas None means "no value" for object.
module Python
{
@@ -76,6 +80,7 @@
| Bytes(bytes s)
| NameConstant(singleton value)
| Ellipsis
+ | Constant(constant value)
-- the following expression can appear in assignment context
| Attribute(expr value, identifier attr, expr_context ctx)