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# Copyright 2017 The TensorFlow Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ==============================================================================
"""Various context managers."""
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
import contextlib
from tensorflow.python.framework import ops
from tensorflow.python.ops import tensor_array_ops
def control_dependency_on_returns(return_value):
"""Create a TF control dependency on the return values of a function.
If the function had no return value, a no-op context is returned.
Args:
return_value: The return value to set as control dependency.
Returns:
A context manager.
"""
def control_dependency_handle(t):
if isinstance(t, tensor_array_ops.TensorArray):
return t.flow
return t
if return_value is None:
return contextlib.contextmanager(lambda: (yield))()
# TODO(mdan): Filter to tensor objects.
if not isinstance(return_value, (list, tuple)):
return_value = (return_value,)
return_value = tuple(control_dependency_handle(t) for t in return_value)
return ops.control_dependencies(return_value)
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