Class CellMagicFinder

src/black/handle_ipynb_magics.py:379–410

r"""Find cell magics. Note that the source of the abstract syntax tree will already have been processed by IPython's TransformerManager().transform_cell. For example, %%time\n foo() would have been transformed to get_ipython().run_cell_magic('time', '

# ast.NodeVisitor + dataclass = breakage under mypyc.
class CellMagicFinder(ast.NodeVisitor):
    r"""Find cell magics.

    Note that the source of the abstract syntax tree
    will already have been processed by IPython's
    TransformerManager().transform_cell.

    For example,

        %%time\n
        foo()

    would have been transformed to

        get_ipython().run_cell_magic('time', '', 'foo()\n')

    and we look for instances of the latter.
    """

    def __init__(self, cell_magic: CellMagic | None = None) -> None:
        self.cell_magic = cell_magic

    def visit_Expr(self, node: ast.Expr) -> None:
        """Find cell magic, extract header and body."""
        if (
            isinstance(node.value, ast.Call)
            and _is_ipython_magic(node.value.func)
            and node.value.func.attr == "run_cell_magic"
        ):
            args = _get_str_args(node.value.args)
            self.cell_magic = CellMagic(name=args[0], params=args[1], body=args[2])
        self.generic_visit(node)


@dataclasses.dataclass(frozen=True)