# This code is part of Qiskit.
#
# (C) Copyright IBM 2017, 2018.
#
# This code is licensed under the Apache License, Version 2.0. You may
# obtain a copy of this license in the LICENSE.txt file in the root directory
# of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
#
# Any modifications or derivative works of this code must retain this
# copyright notice, and modified files need to carry a notice indicating
# that they have been altered from the originals.
"""Fenced objects are wraps for raising TranspilerError when they are modified."""
from .exceptions import TranspilerError
class FencedObject:
"""Given an instance and a list of attributes to fence, raises a TranspilerError when one
of these attributes is accessed."""
def __init__(self, instance, attributes_to_fence):
self._wrapped = instance
self._attributes_to_fence = attributes_to_fence
def __getattribute__(self, name):
object.__getattribute__(self, "_check_if_fenced")(name)
return getattr(object.__getattribute__(self, "_wrapped"), name)
def __getitem__(self, key):
object.__getattribute__(self, "_check_if_fenced")("__getitem__")
return object.__getattribute__(self, "_wrapped")[key]
def __setitem__(self, key, value):
object.__getattribute__(self, "_check_if_fenced")("__setitem__")
object.__getattribute__(self, "_wrapped")[key] = value
def _check_if_fenced(self, name):
"""
Checks if the attribute name is in the list of attributes to protect. If so, raises
TranspilerError.
Args:
name (string): the attribute name to check
Raises:
TranspilerError: when name is the list of attributes to protect.
"""
if name in object.__getattribute__(self, "_attributes_to_fence"):
raise TranspilerError(
"The fenced %s has the property %s protected"
% (type(object.__getattribute__(self, "_wrapped")), name)
)
[docs]class FencedPropertySet(FencedObject):
"""A property set that cannot be written (via __setitem__)"""
def __init__(self, property_set_instance):
super().__init__(property_set_instance, ["__setitem__"])
[docs]class FencedDAGCircuit(FencedObject):
"""A dag circuit that cannot be modified (via remove_op_node)"""
# FIXME: add more fenced methods of the dag after dagcircuit rewrite
def __init__(self, dag_circuit_instance):
super().__init__(dag_circuit_instance, ["remove_op_node"])