Function ExportTensor

cpp/src/arrow/c/dlpack.cc:141–186

};

Result<DLManagedTensor*> ExportTensor(const std::shared_ptr<Tensor>& t) {
  // Define the DLDataType struct
  const DataType& type = *t->type();
  ARROW_ASSIGN_OR_RAISE(auto dlpack_type, GetDLDataType(type));

  // Define DLDevice struct
  ARROW_ASSIGN_OR_RAISE(auto device, ExportDevice(t))

  // Create TensorManagerCtx that will serve as the owner of the DLManagedTensor
  auto ctx = std::make_unique<TensorManagerCtx>();

  // Define the data pointer to the DLTensor
  // If tensor is of length 0, data pointer should be NULL
  if (t->size() == 0) {
    ctx->tensor.dl_tensor.data = NULL;
  } else {
    ctx->tensor.dl_tensor.data = t->raw_mutable_data();
  }

  ctx->tensor.dl_tensor.device = device;
  ctx->tensor.dl_tensor.ndim = t->ndim();
  ctx->tensor.dl_tensor.dtype = dlpack_type;
  ctx->tensor.dl_tensor.byte_offset = 0;

  std::vector<int64_t>& shape_arr = ctx->shape;
  shape_arr.reserve(t->ndim());
  for (auto i : t->shape()) {
    shape_arr.emplace_back(i);
  }
  ctx->tensor.dl_tensor.shape = shape_arr.data();

  std::vector<int64_t>& strides_arr = ctx->strides;
  strides_arr.reserve(t->ndim());
  auto byte_width = t->type()->byte_width();
  for (auto i : t->strides()) {
    strides_arr.emplace_back(i / byte_width);
  }
  ctx->tensor.dl_tensor.strides = strides_arr.data();

  ctx->t = std::move(t);
  ctx->tensor.manager_ctx = ctx.get();
  ctx->tensor.deleter = [](struct DLManagedTensor* self) {
    delete reinterpret_cast<TensorManagerCtx*>(self->manager_ctx);
  };
  return &ctx.release()->tensor;
}

Result<DLDevice> ExportDevice(const std::shared_ptr<Tensor>& t) {
  // Define DLDevice struct