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1 // This file is part of Eigen, a lightweight C++ template library
2 // for linear algebra.
3 //
4 // Copyright (C) 2014 Benoit Steiner <benoit.steiner.goog@gmail.com>
5 //
6 // This Source Code Form is subject to the terms of the Mozilla
7 // Public License v. 2.0. If a copy of the MPL was not distributed
8 // with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
9 
10 #ifndef EIGEN_CXX11_TENSOR_TENSOR_INITIALIZER_H
11 #define EIGEN_CXX11_TENSOR_TENSOR_INITIALIZER_H
12 
13 #if EIGEN_HAS_VARIADIC_TEMPLATES
14 
15 #include <initializer_list>
16 
17 namespace Eigen {
18 
19 /** \class TensorInitializer
20   * \ingroup CXX11_Tensor_Module
21   *
22   * \brief Helper template to initialize Tensors from std::initializer_lists.
23   */
24 namespace internal {
25 
26 template <typename Derived, int N>
27 struct Initializer {
28   typedef std::initializer_list<
29     typename Initializer<Derived, N - 1>::InitList> InitList;
30 
runInitializer31   static void run(TensorEvaluator<Derived, DefaultDevice>& tensor,
32                   Eigen::array<typename traits<Derived>::Index, traits<Derived>::NumDimensions>* indices,
33                   const InitList& vals) {
34     int i = 0;
35     for (auto v : vals) {
36       (*indices)[traits<Derived>::NumDimensions - N] = i++;
37       Initializer<Derived, N - 1>::run(tensor, indices, v);
38     }
39   }
40 };
41 
42 template <typename Derived>
43 struct Initializer<Derived, 1> {
44   typedef std::initializer_list<typename traits<Derived>::Scalar> InitList;
45 
46   static void run(TensorEvaluator<Derived, DefaultDevice>& tensor,
47                   Eigen::array<typename traits<Derived>::Index, traits<Derived>::NumDimensions>* indices,
48                   const InitList& vals) {
49     int i = 0;
50     // There is likely a faster way to do that than iterating.
51     for (auto v : vals) {
52       (*indices)[traits<Derived>::NumDimensions - 1] = i++;
53       tensor.coeffRef(*indices) = v;
54     }
55   }
56 };
57 
58 template <typename Derived>
59 struct Initializer<Derived, 0> {
60   typedef typename traits<Derived>::Scalar InitList;
61 
62   static void run(TensorEvaluator<Derived, DefaultDevice>& tensor,
63                   Eigen::array<typename traits<Derived>::Index, traits<Derived>::NumDimensions>*,
64                   const InitList& v) {
65     tensor.coeffRef(0) = v;
66   }
67 };
68 
69 
70 template <typename Derived, int N>
71 void initialize_tensor(TensorEvaluator<Derived, DefaultDevice>& tensor,
72                        const typename Initializer<Derived, traits<Derived>::NumDimensions>::InitList& vals) {
73   Eigen::array<typename traits<Derived>::Index, traits<Derived>::NumDimensions> indices;
74   Initializer<Derived, traits<Derived>::NumDimensions>::run(tensor, &indices, vals);
75 }
76 
77 }  // namespace internal
78 }  // namespace Eigen
79 
80 #endif  // EIGEN_HAS_VARIADIC_TEMPLATES
81 
82 #endif  // EIGEN_CXX11_TENSOR_TENSOR_INITIALIZER_H
83