From ffc995c9e40ef27cba672738802e989c4ee383d0 Mon Sep 17 00:00:00 2001
From: Jitse Niesen <jitse@maths.leeds.ac.uk>
Date: Wed, 16 Apr 2014 18:16:36 +0100
Subject: Implement evaluator<ReturnByValue>. All supported tests pass apart
 from Sparse and Geometry, except test in adjoint_4 that a = a.transpose()
 raises an assert.

---
 Eigen/src/Core/CoreEvaluators.h | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

(limited to 'Eigen/src')

diff --git a/Eigen/src/Core/CoreEvaluators.h b/Eigen/src/Core/CoreEvaluators.h
index 47f50d548..8df1b706d 100644
--- a/Eigen/src/Core/CoreEvaluators.h
+++ b/Eigen/src/Core/CoreEvaluators.h
@@ -1292,6 +1292,32 @@ private:
   EIGEN_STRONG_INLINE Index colOffset() const { return m_index.value() > 0 ? m_index.value() : 0; }
 };
 
+// -------------------- ReturnByValue --------------------
+
+// Expression is evaluated in a temporary; default implementation of Assignment is bypassed so that
+// when a ReturnByValue expression is assigned, the evaluator is not constructed.
+// TODO: Finalize port to new regime; ReturnByValue should not exist in the expression world
+
+template<typename Derived>
+struct evaluator<ReturnByValue<Derived> > 
+  : evaluator<typename ReturnByValue<Derived>::PlainObject>::type
+{
+  typedef typename ReturnByValue<Derived>::PlainObject PlainObject;
+  typedef typename evaluator<PlainObject>::type Base;
+
+  typedef evaluator type;
+  typedef evaluator nestedType;
+  
+  evaluator(const ReturnByValue<Derived>& xpr)
+    : m_result(xpr.rows(), xpr.cols())
+  {
+    ::new (static_cast<Base*>(this)) Base(m_result);
+    xpr.evalTo(m_result);
+  }
+
+  PlainObject m_result;
+};
+
 } // namespace internal
 
 } // end namespace Eigen
-- 
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