EVOLUTION-MANAGER

Edit File: control_flow_ops.h

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
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http://www.apache.org/licenses/LICENSE-2.0

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distributed under the License is distributed on an "AS IS" BASIS,
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==============================================================================*/

#ifndef TENSORFLOW_CORE_KERNELS_CONTROL_FLOW_OPS_H_
#define TENSORFLOW_CORE_KERNELS_CONTROL_FLOW_OPS_H_

#include "tensorflow/core/framework/op_kernel.h"

namespace tensorflow {

// A ControlTriggerOp is similar to a NoOp. However, it always treats the input
// control edges as Live edges. Its primary use so far is in the scheduling of
// recvs, where we add ControlTrigger nodes and use them to trigger recvs. We
// allow ControlTrigger nodes to be enabled by dead nodes.
class ControlTriggerOp : public OpKernel {
 public:
  explicit ControlTriggerOp(OpKernelConstruction* context)
      : OpKernel(context) {}
  void Compute(OpKernelContext* context) override {}
  bool IsExpensive() override { return false; }
};

// A switch op has two inputs and two outputs. It forwards the value of
// Input:0 to the output specified by input:1. Input:1 is a boolean tensor.
// Input:0 is forwarded to output:0 if input:1 is false, otherwise to
// output:1.
class SwitchOp : public OpKernel {
 public:
  explicit SwitchOp(OpKernelConstruction* context) : OpKernel(context) {}
  void Compute(OpKernelContext* context) override;
  bool IsExpensive() override { return false; }
  ~SwitchOp() override {}

TF_DISALLOW_COPY_AND_ASSIGN(SwitchOp);
};

// An n-way switch op has two inputs and N outputs. It forwards the value of
// Input:0 to the output specified by Input:1. Input:1 is an integer tensor.
// Input:0 is forwarded to output:0 if Input:1 is 0, to output:1 if 1, and so
// forth. If Input:1 is <0 or >=num_outputs(), Input:0 is forwarded to
// output:num_outputs()-1.
class SwitchNOp : public OpKernel {
 public:
  explicit SwitchNOp(OpKernelConstruction* context) : OpKernel(context) {}
  void Compute(OpKernelContext* context) override;
  bool IsExpensive() override { return false; }
  ~SwitchNOp() override {}

TF_DISALLOW_COPY_AND_ASSIGN(SwitchNOp);
};

// A merge op has n inputs and two outputs. It forwards the value of the
// first input that becomes available to its first output, and the
// index of the first input to its second output.
class MergeOp : public OpKernel {
 public:
  explicit MergeOp(OpKernelConstruction* context);
  void Compute(OpKernelContext* context) override;
  bool IsExpensive() override { return false; }
  ~MergeOp() override {}

TF_DISALLOW_COPY_AND_ASSIGN(MergeOp);
};

// An enter op has one input and one output. It creates or finds
// the child frame that is uniquely identified by the frame_name,
// and makes its input available to the child frame.
class EnterOp : public OpKernel {
 public:
  explicit EnterOp(OpKernelConstruction* context) : OpKernel(context) {}
  void Compute(OpKernelContext* context) override;
  bool IsExpensive() override { return false; }
  ~EnterOp() override {}

TF_DISALLOW_COPY_AND_ASSIGN(EnterOp);
};

// An exit op has one input and one output. It exits the current
// frame to its parent frame, and makes its input available to the
// parent frame.
class ExitOp : public OpKernel {
 public:
  explicit ExitOp(OpKernelConstruction* context) : OpKernel(context) {}
  void Compute(OpKernelContext* context) override;
  bool IsExpensive() override { return false; }
  ~ExitOp() override {}

TF_DISALLOW_COPY_AND_ASSIGN(ExitOp);
};

// A next_iteration op has one input and one output. It makes its input
// available to the next iteration.
class NextIterationOp : public OpKernel {
 public:
  explicit NextIterationOp(OpKernelConstruction* context) : OpKernel(context) {}
  void Compute(OpKernelContext* context) override;
  bool IsExpensive() override { return false; }
  ~NextIterationOp() override {}

TF_DISALLOW_COPY_AND_ASSIGN(NextIterationOp);
};

// A LoopCond op has one input and one output. The input is a boolean
// scalar representing the taken branches of the "pivot" Switch that
// determines loop termination. As a contract, any high-level front-end
// should always use port '0' of the "pivot" switches for loop exit.
class LoopCondOp : public OpKernel {
 public:
  explicit LoopCondOp(OpKernelConstruction* context);
  ~LoopCondOp() override;

void Compute(OpKernelContext* context) override;

bool IsExpensive() override;

TF_DISALLOW_COPY_AND_ASSIGN(LoopCondOp);
};

}  // namespace tensorflow

#endif  // TENSORFLOW_CORE_KERNELS_CONTROL_FLOW_OPS_H_