1 files changed, 12 insertions, 0 deletions
diff --git a/Eigen/src/Core/util/Constants.h b/Eigen/src/Core/util/Constants.h
index 3178ff06e..14449eb6c 100644
--- a/Eigen/src/Core/util/Constants.h
+++ b/Eigen/src/Core/util/Constants.h
@@ -440,6 +440,18 @@ struct MatrixXpr {};
 /** The type used to identify an array expression */
 struct ArrayXpr {};
 
+
+#ifdef EIGEN_ENABLE_EVALUATORS
+// An evaluator must define its shape. By default, it can be one of the following:
+struct DenseShape       { static std::string debugName() { return "DenseShape"; } };
+struct DiagonalShape    { static std::string debugName() { return "DiagonalShape"; } };
+struct BandShape        { static std::string debugName() { return "BandShape"; } };
+struct TriangularShape  { static std::string debugName() { return "TriangularShape"; } };
+struct SelfAdjointShape { static std::string debugName() { return "SelfAdjointShape"; } };
+struct SparseShape      { static std::string debugName() { return "SparseShape"; } };
+#endif
+
+
 } // end namespace Eigen
 
 #endif // EIGEN_CONSTANTS_H