1 | /* Copyright 2017 The TensorFlow Authors. All Rights Reserved. |
2 | |
3 | Licensed under the Apache License, Version 2.0 (the "License"); |
4 | you may not use this file except in compliance with the License. |
5 | You may obtain a copy of the License at |
6 | |
7 | http://www.apache.org/licenses/LICENSE-2.0 |
8 | |
9 | Unless required by applicable law or agreed to in writing, software |
10 | distributed under the License is distributed on an "AS IS" BASIS, |
11 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
12 | See the License for the specific language governing permissions and |
13 | limitations under the License. |
14 | ==============================================================================*/ |
15 | |
16 | #ifndef TENSORFLOW_CC_OPS_WHILE_LOOP_H_ |
17 | #define TENSORFLOW_CC_OPS_WHILE_LOOP_H_ |
18 | |
19 | #include <string> |
20 | #include <vector> |
21 | |
22 | #include "tensorflow/cc/framework/ops.h" |
23 | #include "tensorflow/cc/framework/scope.h" |
24 | |
25 | namespace tensorflow { |
26 | namespace ops { |
27 | |
28 | // Function that takes cond graph inputs and returns cond graph boolean output. |
29 | // 'output' need not be set if an error is returned. |
30 | typedef std::function<Status(const Scope&, const std::vector<Output>& inputs, |
31 | Output* output)> |
32 | CondGraphBuilderFn; |
33 | |
34 | // Function that takes body graph inputs and returns body graph outputs. |
35 | // 'outputs' need not be populated if an error is returned. |
36 | typedef std::function<Status(const Scope&, const std::vector<Output>& inputs, |
37 | std::vector<Output>* outputs)> |
38 | BodyGraphBuilderFn; |
39 | |
40 | // Constructs a while loop. |
41 | // |
42 | // Arguments: |
43 | // * scope: used to construct the while loop. |
44 | // * inputs: the initial values of the loop variables. Must be non-empty. |
45 | // * cond: a function that builds the condition graph of the loop. Takes the |
46 | // current loop variables as inputs and returns a scalar boolean Output |
47 | // indicating whether the loop should continue. |
48 | // * body: a function that builds the body graph of the loop. Takes the current |
49 | // loop variables as inputs and returns the updated loop variables. |
50 | // * frame_name: the frame name to use for this while loop. This should be a |
51 | // unique name. This will be used as a prefix for created operations. |
52 | // * outputs: output param that returns final loop variable outputs in non-error |
53 | // case. Must be non-null and empty. |
54 | // * create_while_ctx: if true, a WhileContext is created and populated for this |
55 | // loop. See core/graph/while_context.h for more details on |
56 | // WhileContexts. This is set to false for loops used as part of gradient |
57 | // computations, since they're part of the gradient for a loop in the |
58 | // forward-pass. |
59 | // TODO(skyewm): revisit this. Should we create WhileContexts for all loops, |
60 | // even if we don't need them? |
61 | // * cond_output: if non-null, the output of the predicate is returned. This |
62 | // will always be a LoopCond node. |
63 | // |
64 | // Returns an error if the while loop could not be fully constructed. |
65 | // |
66 | // TODO(skyewm): clean up partially-constructed loop in error case |
67 | // TODO(skyewm): create public interface to this method |
68 | Status BuildWhileLoop(const Scope& scope, const std::vector<Output>& inputs, |
69 | const CondGraphBuilderFn& cond, |
70 | const BodyGraphBuilderFn& body, const string& frame_name, |
71 | OutputList* outputs, bool create_while_ctx = true, |
72 | Output* cond_output = nullptr); |
73 | |
74 | } // namespace ops |
75 | } // namespace tensorflow |
76 | |
77 | #endif // TENSORFLOW_CC_OPS_WHILE_LOOP_H_ |
78 | |