!2946 Added empty tensor support

Merge pull request !2946 from EricZ/emtpy-tensor

mindspore/ccsrc/dataset/core/tensor.cc

@@ -513,6 +513,15 @@ const unsigned char *Tensor::GetBuffer() const {
   return data_;
 }
 
+// check for empty
+bool Tensor::HasData() const {
+  if (data_ == nullptr) {
+    return true;
+  } else {
+    return false;
+  }
+}
+
 unsigned char *Tensor::GetMutableBuffer() {
   if (!shape_.known() || type_ == DataType::DE_UNKNOWN) {
     return nullptr;

mindspore/ccsrc/dataset/core/tensor.h

@@ -277,6 +277,10 @@ class Tensor {
   // @return
   const TensorShape &shape() const { return shape_; }
 
+  /// Check if tensor has data
+  /// \return bool - true if tensor is empty
+  bool HasData() const;
+
   // Reshape the tensor. The given shape should have the same number of elements in the Tensor
   // @param shape
   virtual Status Reshape(const TensorShape &shape);

tests/ut/cpp/dataset/tensor_test.cc

@@ -432,3 +432,17 @@ TEST_F(MindDataTestTensorDE, TensorConcatenate) {
   s = t1->Concatenate({5}, t2);
   EXPECT_FALSE(s.IsOk());
 }
+
+TEST_F(MindDataTestTensorDE, TensorEmpty) {
+  std::shared_ptr<Tensor> t = std::make_shared<Tensor>(TensorShape({2, 3}), DataType(DataType::DE_UINT64));
+  ASSERT_TRUE(t->HasData());
+}
+
+TEST_F(MindDataTestTensorDE, TensorEmptyInvalidate) {
+  std::vector<uint32_t> values1 = {1, 2, 3, 0, 0, 0};
+  std::shared_ptr<Tensor> t;
+  Tensor::CreateTensor(&t, values1);
+  t->Invalidate();
+  ASSERT_TRUE(t->HasData());
+}
+