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| author | Guido van Rossum <guido@python.org> | 2019-03-07 20:38:08 (GMT) |
|---|---|---|
| committer | Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com> | 2019-03-07 20:38:08 (GMT) |
| commit | 495da292255b92dd73758fdd0e4c7d27d82b1e57 (patch) | |
| tree | 1378cf049d2d125593fa970ea1e9a9f77604fab1 /Doc/library/ast.rst | |
| parent | bf94cc7b496a379e1f604aa2e4080bb70ca4020e (diff) | |
| download | cpython-495da292255b92dd73758fdd0e4c7d27d82b1e57.zip cpython-495da292255b92dd73758fdd0e4c7d27d82b1e57.tar.gz cpython-495da292255b92dd73758fdd0e4c7d27d82b1e57.tar.bz2 | |
bpo-35975: Support parsing earlier minor versions of Python 3 (GH-12086)
This adds a `feature_version` flag to `ast.parse()` (documented) and `compile()` (hidden) that allow tweaking the parser to support older versions of the grammar. In particular if `feature_version` is 5 or 6, the hacks for the `async` and `await` keyword from PEP 492 are reinstated. (For 7 or higher, these are unconditionally treated as keywords, but they are still special tokens rather than `NAME` tokens that the parser driver recognizes.)
https://bugs.python.org/issue35975
Diffstat (limited to 'Doc/library/ast.rst')
| -rw-r--r-- | Doc/library/ast.rst | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/Doc/library/ast.rst b/Doc/library/ast.rst index 3df7f9e..1884bea 100644 --- a/Doc/library/ast.rst +++ b/Doc/library/ast.rst @@ -126,7 +126,7 @@ The abstract grammar is currently defined as follows: 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) +.. function:: parse(source, filename='<unknown>', mode='exec', *, type_comments=False, feature_version=-1) Parse the source into an AST node. Equivalent to ``compile(source, filename, mode, ast.PyCF_ONLY_AST)``. @@ -145,13 +145,19 @@ and classes for traversing abstract syntax trees: 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]``. + .. warning:: It is possible to crash the Python interpreter with a sufficiently large/complex string due to stack depth limitations in Python's AST compiler. .. versionchanged:: 3.8 - Added ``type_comments=True`` and ``mode='func_type'``. + Added ``type_comments``, ``mode='func_type'`` and ``feature_version``. .. function:: literal_eval(node_or_string) |