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+# Copyright 2016 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.
+# ==============================================================================
+"""Utilities for type-dependent behavior used in autograph-generated code."""
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+from tensorflow.python.autograph.utils.type_check import is_tensor
+from tensorflow.python.ops import control_flow_ops
+
+
+def run_cond(condition, true_fn, false_fn):
+ """Type-dependent functional conditional.
+
+ Args:
+ condition: A Tensor or Python bool.
+ true_fn: A Python callable implementing the true branch of the conditional.
+ false_fn: A Python callable implementing the false branch of the
+ conditional.
+
+ Returns:
+ result: The result of calling the appropriate branch. If condition is a
+ Tensor, tf.cond will be used. Otherwise, a standard Python if statement will
+ be ran.
+ """
+ if is_tensor(condition):
+ return control_flow_ops.cond(condition, true_fn, false_fn)
+ else:
+ return py_cond(condition, true_fn, false_fn)
+
+
+def py_cond(condition, true_fn, false_fn):
+ """Functional version of Python's conditional."""
+ if condition:
+ results = true_fn()
+ else:
+ results = false_fn()
+
+ # The contract for the branch functions is to return tuples, but they should
+ # be collapsed to a single element when there is only one output.
+ if len(results) == 1:
+ return results[0]
+ return results