def _emulate_yield_from(self, targets: Optional[List[ast.Name]],
node: ast.YieldFrom) -> Iterable[ast.AST]:
generator = ast.Name(
id='_py_backwards_generator_{}'.format(self._name_suffix))
exception = ast.Name(
id='_py_backwards_generator_exception_{}'.format(self._name_suffix))
yield ast.Assign(targets=[generator],
value=ast.Call(func=ast.Name(id='iter'),
args=[node.value],
keywords=[]))
assign_to_targets = [
ast.If(test=ast.Call(func=ast.Name(id='hasattr'), args=[
exception, ast.Str(s='value'),
], keywords=[]), body=[
ast.Assign(targets=targets,
value=ast.Attribute(
value=exception, attr='value')),
], orelse=[]),
ast.Break()] if targets else [ast.Break()]
yield ast.While(test=ast.NameConstant(value=True), body=[
ast.Try(body=[
ast.Expr(value=ast.Yield(value=ast.Call(
func=ast.Name(id='next'),
args=[generator], keywords=[]))),
], handlers=[
ast.ExceptHandler(
type=ast.Name(id='StopIteration'),
name=exception.id,
body=assign_to_targets),
], orelse=[], finalbody=[]),
], orelse=[])
self._name_suffix += 1
def visit_ExceptHandler(self, n):
if n.name is None:
name = None
elif isinstance(n.name, ast27.Name):
name = n.name.id
else:
raise RuntimeError("'{}' has non-Name name.".format(ast27.dump(n)))
return ast3.ExceptHandler(self.maybe_visit(n.type), name, self.visit(n.body))