From bb2d70d211a8fc8184b690b75d29ba484edace0e Mon Sep 17 00:00:00 2001
From: Jitse Niesen <jitse@maths.leeds.ac.uk>
Date: Fri, 22 Apr 2011 22:36:45 +0100
Subject: [PATCH] Implement evaluators for ArrayWrapper and MatrixWrapper.

---
 Eigen/src/Core/ArrayWrapper.h             | 12 ++++
 Eigen/src/Core/CoreEvaluators.h           | 85 ++++++++++++++++++++++-
 Eigen/src/Core/util/ForwardDeclarations.h |  1 +
 test/evaluators.cpp                       | 12 ++++
 4 files changed, 109 insertions(+), 1 deletion(-)

diff --git a/Eigen/src/Core/ArrayWrapper.h b/Eigen/src/Core/ArrayWrapper.h
index 7ba01de36..6c7e2b198 100644
--- a/Eigen/src/Core/ArrayWrapper.h
+++ b/Eigen/src/Core/ArrayWrapper.h
@@ -119,6 +119,12 @@ class ArrayWrapper : public ArrayBase<ArrayWrapper<ExpressionType> >
     template<typename Dest>
     inline void evalTo(Dest& dst) const { dst = m_expression; }
 
+    const typename internal::remove_all<NestedExpressionType>::type& 
+    nestedExpression() const 
+    {
+      return m_expression;
+    }
+
   protected:
     const NestedExpressionType m_expression;
 };
@@ -214,6 +220,12 @@ class MatrixWrapper : public MatrixBase<MatrixWrapper<ExpressionType> >
       m_expression.const_cast_derived().template writePacket<LoadMode>(index, x);
     }
 
+    const typename internal::remove_all<NestedExpressionType>::type& 
+    nestedExpression() const 
+    {
+      return m_expression;
+    }
+
   protected:
     const NestedExpressionType m_expression;
 };
diff --git a/Eigen/src/Core/CoreEvaluators.h b/Eigen/src/Core/CoreEvaluators.h
index 6b08c78a0..47835f576 100644
--- a/Eigen/src/Core/CoreEvaluators.h
+++ b/Eigen/src/Core/CoreEvaluators.h
@@ -106,7 +106,7 @@ protected:
   typename evaluator<ExpressionType>::type m_argImpl;
 };
 
-// -------------------- Matrix and Array--------------------
+// -------------------- Matrix and Array --------------------
 //
 // evaluator_impl<PlainObjectBase> is a common base class for the
 // Matrix and Array evaluators.
@@ -704,6 +704,89 @@ protected:
 };
 
 
+// -------------------- MatrixWrapper and ArrayWrapper --------------------
+//
+// evaluator_impl_wrapper_base<T> is a common base class for the
+// MatrixWrapper and ArrayWrapper evaluators.
+
+template<typename ArgType>
+struct evaluator_impl_wrapper_base
+{
+  evaluator_impl_wrapper_base(const ArgType& arg) : m_argImpl(arg) {}
+
+  typedef typename ArgType::Index Index;
+  typedef typename ArgType::Scalar Scalar;
+  typedef typename ArgType::CoeffReturnType CoeffReturnType;
+  typedef typename ArgType::PacketScalar PacketScalar;
+  typedef typename ArgType::PacketReturnType PacketReturnType;
+
+  CoeffReturnType coeff(Index row, Index col) const
+  {
+    return m_argImpl.coeff(row, col);
+  }
+
+  CoeffReturnType coeff(Index index) const
+  {
+    return m_argImpl.coeff(index);
+  }
+
+  Scalar& coeffRef(Index row, Index col)
+  {
+    return m_argImpl.coeffRef(row, col);
+  }
+
+  Scalar& coeffRef(Index index)
+  {
+    return m_argImpl.coeffRef(index);
+  }
+
+  template<int LoadMode> 
+  PacketReturnType packet(Index row, Index col) const
+  {
+    return m_argImpl.template packet<LoadMode>(row, col);
+  }
+
+  template<int LoadMode> 
+  PacketReturnType packet(Index index) const
+  {
+    return m_argImpl.template packet<LoadMode>(index);
+  }
+
+  template<int StoreMode> 
+  void writePacket(Index row, Index col, const PacketScalar& x)
+  {
+    m_argImpl.template writePacket<StoreMode>(row, col, x);
+  }
+
+  template<int StoreMode> 
+  void writePacket(Index index, const PacketScalar& x)
+  {
+    m_argImpl.template writePacket<StoreMode>(index, x);
+  }
+
+protected:
+  typename evaluator<ArgType>::type m_argImpl;
+};
+
+template<typename ArgType>
+struct evaluator_impl<MatrixWrapper<ArgType> >
+  : evaluator_impl_wrapper_base<ArgType>
+{
+  evaluator_impl(const MatrixWrapper<ArgType>& wrapper) 
+    : evaluator_impl_wrapper_base<ArgType>(wrapper.nestedExpression())
+  { }
+};
+
+template<typename ArgType>
+struct evaluator_impl<ArrayWrapper<ArgType> >
+  : evaluator_impl_wrapper_base<ArgType>
+{
+  evaluator_impl(const ArrayWrapper<ArgType>& wrapper) 
+    : evaluator_impl_wrapper_base<ArgType>(wrapper.nestedExpression())
+  { }
+};
+
+
 } // namespace internal
 
 #endif // EIGEN_COREEVALUATORS_H
diff --git a/Eigen/src/Core/util/ForwardDeclarations.h b/Eigen/src/Core/util/ForwardDeclarations.h
index 7fbccf98c..ce784daed 100644
--- a/Eigen/src/Core/util/ForwardDeclarations.h
+++ b/Eigen/src/Core/util/ForwardDeclarations.h
@@ -133,6 +133,7 @@ template<typename ExpressionType> class WithFormat;
 template<typename MatrixType> struct CommaInitializer;
 template<typename Derived> class ReturnByValue;
 template<typename ExpressionType> class ArrayWrapper;
+template<typename ExpressionType> class MatrixWrapper;
 
 namespace internal {
 template<typename DecompositionType, typename Rhs> struct solve_retval_base;
diff --git a/test/evaluators.cpp b/test/evaluators.cpp
index 4c55736eb..da6b9064b 100644
--- a/test/evaluators.cpp
+++ b/test/evaluators.cpp
@@ -180,4 +180,16 @@ void test_evaluators()
   VectorXd vec1(6);
   VERIFY_IS_APPROX_EVALUATOR(vec1, mat1.rowwise().sum());
   VERIFY_IS_APPROX_EVALUATOR(vec1, mat1.colwise().sum().transpose());
+
+  // test MatrixWrapper and ArrayWrapper
+  mat1.setRandom(6,6);
+  arr1.setRandom(6,6);
+  VERIFY_IS_APPROX_EVALUATOR(mat2, arr1.matrix());
+  VERIFY_IS_APPROX_EVALUATOR(arr2, mat1.array());
+  VERIFY_IS_APPROX_EVALUATOR(mat2, (arr1 + 2).matrix());
+  VERIFY_IS_APPROX_EVALUATOR(arr2, mat1.array() + 2);
+  mat2.array() = arr1 * arr1;
+  VERIFY_IS_APPROX(mat2, (arr1 * arr1).matrix());
+  arr2.matrix() = MatrixXd::Identity(6,6);
+  VERIFY_IS_APPROX(arr2, MatrixXd::Identity(6,6).array());
 }