From c94174b4fe76636ae5f027ad8e59023cd154d90d Mon Sep 17 00:00:00 2001
From: Benoit Steiner <benoit.steiner.goog@gmail.com>
Date: Wed, 14 Jan 2015 10:13:08 -0800
Subject: Improved tensor references

---
 unsupported/Eigen/CXX11/src/Tensor/TensorRef.h | 73 +++++++++++++++++++++++++-
 1 file changed, 71 insertions(+), 2 deletions(-)

(limited to 'unsupported/Eigen/CXX11/src/Tensor/TensorRef.h')

diff --git a/unsupported/Eigen/CXX11/src/Tensor/TensorRef.h b/unsupported/Eigen/CXX11/src/Tensor/TensorRef.h
index d43fb286e..0a87e67eb 100644
--- a/unsupported/Eigen/CXX11/src/Tensor/TensorRef.h
+++ b/unsupported/Eigen/CXX11/src/Tensor/TensorRef.h
@@ -64,7 +64,7 @@ class TensorLazyEvaluatorReadOnly : public TensorLazyBaseEvaluator<Dimensions, t
   virtual const Scalar coeff(DenseIndex index) const {
     return m_impl.coeff(index);
   }
-  virtual Scalar& coeffRef(DenseIndex) {
+  virtual Scalar& coeffRef(DenseIndex /*index*/) {
     eigen_assert(false && "can't reference the coefficient of a rvalue");
     return *reinterpret_cast<Scalar*>(dummy);
   };
@@ -137,6 +137,8 @@ template<typename PlainObjectType> class TensorRef : public TensorBase<TensorRef
     enum {
       IsAligned = false,
       PacketAccess = false,
+      Layout = PlainObjectType::Layout,
+      CoordAccess = false,  // to be implemented
     };
 
     EIGEN_STRONG_INLINE TensorRef() : m_evaluator(NULL) {
@@ -174,6 +176,8 @@ template<typename PlainObjectType> class TensorRef : public TensorBase<TensorRef
       return *this;
     }
 
+    EIGEN_DEVICE_FUNC
+    EIGEN_STRONG_INLINE Index rank() const { return m_evaluator->dimensions().size(); }
     EIGEN_DEVICE_FUNC
     EIGEN_STRONG_INLINE Index dimension(Index n) const { return m_evaluator->dimensions()[n]; }
     EIGEN_DEVICE_FUNC
@@ -197,6 +201,13 @@ template<typename PlainObjectType> class TensorRef : public TensorBase<TensorRef
       const array<Index, NumIndices> indices{{firstIndex, otherIndices...}};
       return coeff(indices);
     }
+    template<typename... IndexTypes> EIGEN_DEVICE_FUNC
+    EIGEN_STRONG_INLINE Scalar& coeffRef(Index firstIndex, IndexTypes... otherIndices)
+    {
+      const std::size_t NumIndices = (sizeof...(otherIndices) + 1);
+      const array<Index, NumIndices> indices{{firstIndex, otherIndices...}};
+      return coeffRef(indices);
+    }
 #else
 
     EIGEN_DEVICE_FUNC
@@ -237,6 +248,44 @@ template<typename PlainObjectType> class TensorRef : public TensorBase<TensorRef
       indices[4] = i4;
       return coeff(indices);
     }
+    EIGEN_DEVICE_FUNC
+    EIGEN_STRONG_INLINE Scalar& coeffRef(Index i0, Index i1)
+    {
+      array<Index, 2> indices;
+      indices[0] = i0;
+      indices[1] = i1;
+      return coeffRef(indices);
+    }
+    EIGEN_DEVICE_FUNC
+    EIGEN_STRONG_INLINE Scalar& coeffRef(Index i0, Index i1, Index i2)
+    {
+      array<Index, 3> indices;
+      indices[0] = i0;
+      indices[1] = i1;
+      indices[2] = i2;
+      return coeffRef(indices);
+    }
+    EIGEN_DEVICE_FUNC
+    EIGEN_STRONG_INLINE Scalar& operator()(Index i0, Index i1, Index i2, Index i3)
+    {
+      array<Index, 4> indices;
+      indices[0] = i0;
+      indices[1] = i1;
+      indices[2] = i2;
+      indices[3] = i3;
+      return coeffRef(indices);
+    }
+    EIGEN_DEVICE_FUNC
+    EIGEN_STRONG_INLINE Scalar& coeffRef(Index i0, Index i1, Index i2, Index i3, Index i4)
+    {
+      array<Index, 5> indices;
+      indices[0] = i0;
+      indices[1] = i1;
+      indices[2] = i2;
+      indices[3] = i3;
+      indices[4] = i4;
+      return coeffRef(indices);
+    }
 #endif
 
     template <std::size_t NumIndices> EIGEN_DEVICE_FUNC
@@ -244,7 +293,7 @@ template<typename PlainObjectType> class TensorRef : public TensorBase<TensorRef
     {
       const Dimensions& dims = this->dimensions();
       Index index = 0;
-      if (PlainObjectType::Options&RowMajor) {
+      if (PlainObjectType::Options & RowMajor) {
         index += indices[0];
         for (int i = 1; i < NumIndices; ++i) {
           index = index * dims[i] + indices[i];
@@ -257,6 +306,24 @@ template<typename PlainObjectType> class TensorRef : public TensorBase<TensorRef
       }
       return m_evaluator->coeff(index);
     }
+    template <std::size_t NumIndices> EIGEN_DEVICE_FUNC
+    EIGEN_STRONG_INLINE Scalar& coeffRef(const array<Index, NumIndices>& indices)
+    {
+      const Dimensions& dims = this->dimensions();
+      Index index = 0;
+      if (PlainObjectType::Options & RowMajor) {
+        index += indices[0];
+        for (int i = 1; i < NumIndices; ++i) {
+          index = index * dims[i] + indices[i];
+        }
+      } else {
+        index += indices[NumIndices-1];
+        for (int i = NumIndices-2; i >= 0; --i) {
+          index = index * dims[i] + indices[i];
+        }
+      }
+      return m_evaluator->coeffRef(index);
+    }
 
     EIGEN_DEVICE_FUNC
     EIGEN_STRONG_INLINE const Scalar coeff(Index index) const
@@ -298,6 +365,8 @@ struct TensorEvaluator<const TensorRef<Derived>, Device>
   enum {
     IsAligned = false,
     PacketAccess = false,
+    Layout = TensorRef<Derived>::Layout,
+    CoordAccess = false,  // to be implemented
   };
 
   EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE TensorEvaluator(const TensorRef<Derived>& m, const Device&)
-- 
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