Added a move constructor and move assignment operator to Tensor and wrote some tests.

Author: ViktorC

unsupported/Eigen/CXX11/src/Tensor/Tensor.h

@@ -398,6 +398,21 @@ class Tensor : public TensorBase<Tensor<Scalar_, NumIndices_, Options_, IndexTyp
       internal::TensorExecutor<const Assign, DefaultDevice>::run(assign, DefaultDevice());
     }
 
+    #if EIGEN_HAS_RVALUE_REFERENCES
+    EIGEN_DEVICE_FUNC
+    EIGEN_STRONG_INLINE Tensor(Self&& other)
+      : Tensor()
+    {
+      m_storage.swap(other.m_storage);
+    }
+    EIGEN_DEVICE_FUNC
+    EIGEN_STRONG_INLINE Tensor& operator=(Self&& other)
+    {
+      m_storage.swap(other.m_storage);
+      return *this;
+    }
+    #endif
+
     EIGEN_DEVICE_FUNC
     EIGEN_STRONG_INLINE Tensor& operator=(const Tensor& other)
     {

unsupported/test/CMakeLists.txt

@@ -225,6 +225,7 @@ if(EIGEN_TEST_CXX11)
   ei_add_test(cxx11_tensor_ifft)
   ei_add_test(cxx11_tensor_scan)
   ei_add_test(cxx11_tensor_trace)
+  ei_add_test(cxx11_tensor_move)
 
 endif()
 

unsupported/test/cxx11_tensor_move.cpp

@@ -0,0 +1,81 @@
+// This file is part of Eigen, a lightweight C++ template library
+// for linear algebra.
+//
+// Copyright (C) 2017 Viktor Csomor <[email protected]>
+//
+// This Source Code Form is subject to the terms of the Mozilla
+// Public License v. 2.0. If a copy of the MPL was not distributed
+// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#include "main.h"
+
+#include <Eigen/CXX11/Tensor>
+#include <utility>
+
+using Eigen::Tensor;
+using Eigen::RowMajor;
+
+static void calc_indices(int i, int& x, int& y, int& z)
+{
+  x = i / 4;
+  y = (i % 4) / 2;
+  z = i % 2;
+}
+
+static void test_move()
+{
+  int x;
+  int y;
+  int z;
+
+  Tensor<int,3> tensor1(2, 2, 2);
+  Tensor<int,3,RowMajor> tensor2(2, 2, 2);
+
+  for (int i = 0; i < 8; i++)
+  {
+    calc_indices(i, x, y, z);
+    tensor1(x,y,z) = i;
+    tensor2(x,y,z) = 2 * i;
+  }
+
+  // Invokes the move constructor.
+  Tensor<int,3> moved_tensor1 = std::move(tensor1);
+  Tensor<int,3,RowMajor> moved_tensor2 = std::move(tensor2);
+
+  VERIFY_IS_EQUAL(tensor1.size(), 0);
+  VERIFY_IS_EQUAL(tensor2.size(), 0);
+
+  for (int i = 0; i < 8; i++)
+  {
+    calc_indices(i, x, y, z);
+    VERIFY_IS_EQUAL(moved_tensor1(x,y,z), i);
+    VERIFY_IS_EQUAL(moved_tensor2(x,y,z), 2 * i);
+  }
+
+  Tensor<int,3> moved_tensor3(2,2,2);
+  Tensor<int,3,RowMajor> moved_tensor4(2,2,2);
+
+  moved_tensor3.setZero();
+  moved_tensor4.setZero();
+
+  // Invokes the move assignment operator.
+  moved_tensor3 = std::move(moved_tensor1);
+  moved_tensor4 = std::move(moved_tensor2);
+
+  VERIFY_IS_EQUAL(moved_tensor1.size(), 8);
+  VERIFY_IS_EQUAL(moved_tensor2.size(), 8);
+
+  for (int i = 0; i < 8; i++)
+  {
+    calc_indices(i, x, y, z);
+    VERIFY_IS_EQUAL(moved_tensor1(x,y,z), 0);
+    VERIFY_IS_EQUAL(moved_tensor2(x,y,z), 0);
+    VERIFY_IS_EQUAL(moved_tensor3(x,y,z), i);
+    VERIFY_IS_EQUAL(moved_tensor4(x,y,z), 2 * i);
+  }
+}
+
+EIGEN_DECLARE_TEST(cxx11_tensor_move)
+{
+  CALL_SUBTEST(test_move());
+}