def test_transform_bad_tree():
with pytest.raises(TypeError):
_ = list(op_tree.transform_op_tree(None))
with pytest.raises(TypeError):
_ = list(op_tree.transform_op_tree(5))
with pytest.raises(TypeError):
_ = list(op_tree.flatten_op_tree(op_tree.transform_op_tree([
Operation(Gate(), [QubitId()]), (4,)
])))
def control(controllee: op_tree.OP_TREE,
control_qubits: Sequence['cirq.Qid'] = None,
default: Any = RaiseTypeErrorIfNotProvided) -> Any:
"""Returns a Controlled version of the given value, if defined.
Controllees define how to be controlled by defining a method
controlled_by(self, control_qubits). Note that the method may return
NotImplemented to indicate a particular controlling can't be done.
Args:
controllee: The operation or iterable of operations to control.
control_qubits: A list of Qids that would control this controllee.
default: Determines the fallback behavior when `controllee` doesn't
have a controlling defined. If `default` is not set and the
fallback occurs, a TypeError is raised instead.
TODO: add control_values and control_qid_shape
Returns:
If `controllee` has a controlled_by method that returns something
besides NotImplemented, that result is returned. For an OP_TREE,
transformation is applied at the leaf. Otherwise, if a default value
was specified, the default value is returned.
Raises:
TypeError: `controllee` doesn't have a controlled_by method (or that
method returned NotImplemented) and no `default` was specified.
"""
if control_qubits is None:
control_qubits = []
controller = getattr(controllee, 'controlled_by', None)
result = NotImplemented if controller is None else controller(
*control_qubits)
if result is not NotImplemented:
return result
if isinstance(controllee, Iterable):
return op_tree.transform_op_tree(
controllee,
op_transformation=lambda op: control(op, control_qubits))
if default is not RaiseTypeErrorIfNotProvided:
return default
if controller is None:
raise TypeError("object of type '{}' has no controlled_by "
"method.".format(type(controllee)))
raise TypeError("object of type '{}' does have a controlled_by method, "
"but it returned NotImplemented.".format(type(controllee)))
def inverse(root: op_tree.OP_TREE,
extensions: Extensions = None) -> op_tree.OP_TREE:
"""Generates OP_TREE inverses.
Args:
root: An operation tree containing only invertible operations.
extensions: For caller-provided implementations of gate inverses.
Returns:
An OP_TREE that performs the inverse operation of the given OP_TREE.
"""
ext = extensions or Extensions()
return op_tree.transform_op_tree(
root=root,
op_transformation=lambda e: _reverse_operation(e, ext),
iter_transformation=lambda e: reversed(list(e)))
def skip_tree_freeze(root):
return op_tree.freeze_op_tree(
op_tree.transform_op_tree(root, iter_transformation=skip_first))
def move_tree_left_freeze(root):
return op_tree.freeze_op_tree(
op_tree.transform_op_tree(root, move_left))