def _preparse(
source: str,
f=_compose(
_replace_locals, _replace_booleans, _rewrite_assign, clean_backtick_quoted_toks
),
):
"""Compose a collection of tokenization functions
Parameters
----------
source : str
A Python source code string
f : callable
This takes a tuple of (toknum, tokval) as its argument and returns a
tuple with the same structure but possibly different elements. Defaults
to the composition of ``_rewrite_assign``, ``_replace_booleans``, and
``_replace_locals``.
Returns
-------
s : str
Valid Python source code
Notes
-----
The `f` parameter can be any callable that takes *and* returns input of the
form ``(toknum, tokval)``, where ``toknum`` is one of the constants from
the ``tokenize`` module and ``tokval`` is a string.
"""
assert callable(f), "f must be callable"
return tokenize.untokenize((f(x) for x in tokenize_string(source)))
def _check_for_locals(expr: str, stack_level: int, parser: str):
at_top_of_stack = stack_level == 0
not_pandas_parser = parser != "pandas"
if not_pandas_parser:
msg = "The '@' prefix is only supported by the pandas parser"
elif at_top_of_stack:
msg = (
"The '@' prefix is not allowed in top-level eval calls.\n"
"please refer to your variables by name without the '@' prefix.")
if at_top_of_stack or not_pandas_parser:
for toknum, tokval in tokenize_string(expr):
if toknum == tokenize.OP and tokval == "@":
raise SyntaxError(msg)
