caffe2/operators/if_op.cc

#include "caffe2/operators/if_op.h"

namespace caffe2 {

template <>
bool IfOp<CPUContext>::RunOnDevice() {
  CAFFE_ENFORCE_GT(
      InputSize(), 0, "Condition must be specified in If operator");
  CAFFE_ENFORCE(
      InputIsType<Tensor<CPUContext>>(0),
      "Invalid condition in If operator: tensor expected");

  const auto& condition = Input(0);
  CAFFE_ENFORCE(
      condition.IsType<bool>(),
      "Invalid condition tensor in If operator: boolean expected");
  CAFFE_ENFORCE_EQ(
      condition.size(),
      1,
      "Invalid condition tensor in If operator: single value expected");
  CAFFE_ENFORCE_EQ(
      condition.ndim(),
      0,
      "Invalid condition tensor in If operator: scalar expected");

  auto conditionValue = *condition.data<bool>();
  auto* netToExecute =
      conditionValue ? then_net_ : (else_net_ ? else_net_ : nullptr);

  return netToExecute ? netToExecute->Run() : true;
}

REGISTER_CPU_OPERATOR(If, IfOp<CPUContext>);

OPERATOR_SCHEMA(If)
    .NumInputs(1, INT_MAX)
    .NumOutputs(0, INT_MAX)
    .SetDoc(R"DOC(
'If' control operator, first input is a scalar boolean blob that stores condition
value. Accepts 'then_net' (required) and 'else_net' (optional) arguments for 'then' and
'else' subnets respectively. Subnets are executed in the same workspace as 'If'.
    )DOC")
    .Arg("then_net", "Net executed when condition is true")
    .Arg("else_net", "Net executed when condition is false (optional)")
    .Input(0, "condition", "Scalar boolean condition")
    .AllowInplace([](int in, int out) -> bool { return true; });

} // namespace caffe2