# Copyright 2018 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.
# ==============================================================================
"""Gradient functions for optional ops."""

from tensorflow.python.framework import ops
from tensorflow.python.ops import gen_optional_ops


@ops.RegisterGradient("OptionalFromValue")
def _OptionalFromValueGrad(op, grad):
  return gen_optional_ops.optional_get_value(
      grad, [t.dtype for t in op.inputs], [t.shape for t in op.inputs]
  )


@ops.RegisterGradient("OptionalGetValue")
def _OptionalGetValueGrad(unused_op, *grads):
  return gen_optional_ops.optional_from_value(grads)