Apart from the node classes, the :mod:`ast` module defines these utility functions
and classes for traversing abstract syntax trees:
-.. function:: parse(source, filename='<unknown>', mode='exec', *, type_comments=False, feature_version=-1)
+.. function:: parse(source, filename='<unknown>', mode='exec', *, type_comments=False, feature_version=None)
Parse the source into an AST node. Equivalent to ``compile(source,
filename, mode, ast.PyCF_ONLY_AST)``.
modified to correspond to :pep:`484` "signature type comments",
e.g. ``(str, int) -> List[str]``.
- Also, setting ``feature_version`` to the minor version of an
- earlier Python 3 version will attempt to parse using that version's
- grammar. For example, setting ``feature_version=4`` will allow
- the use of ``async`` and ``await`` as variable names. The lowest
- supported value is 4; the highest is ``sys.version_info[1]``.
+ Also, setting ``feature_version`` to a tuple ``(major, minor)``
+ will attempt to parse using that Python version's grammar.
+ Currently ``major`` must equal to ``3``. For example, setting
+ ``feature_version=(3, 4)`` will allow the use of ``async`` and
+ ``await`` as variable names. The lowest supported version is
+ ``(3, 4)``; the highest is ``sys.version_info[0:2]``.
.. warning::
It is possible to crash the Python interpreter with a
* ``mode='func_type'`` can be used to parse :pep:`484` "signature type
comments" (returned for function definition AST nodes);
-* ``feature_version=N`` allows specifying the minor version of an
- earlier Python 3 version. (For example, ``feature_version=4`` will
- treat ``async`` and ``await`` as non-reserved words.)
+* ``feature_version=(3, N)`` allows specifying an earlier Python 3
+ version. (For example, ``feature_version=(3, 4)`` will treat
+ ``async`` and ``await`` as non-reserved words.)
New function :func:`ast.get_source_segment` returns the source code
for a specific AST node.
def parse(source, filename='<unknown>', mode='exec', *,
- type_comments=False, feature_version=-1):
+ type_comments=False, feature_version=None):
"""
Parse the source into an AST node.
Equivalent to compile(source, filename, mode, PyCF_ONLY_AST).
flags = PyCF_ONLY_AST
if type_comments:
flags |= PyCF_TYPE_COMMENTS
+ if isinstance(feature_version, tuple):
+ major, minor = feature_version # Should be a 2-tuple.
+ assert major == 3
+ feature_version = minor
+ elif feature_version is None:
+ feature_version = -1
+ # Else it should be an int giving the minor version for 3.x.
return compile(source, filename, mode, flags,
feature_version=feature_version)