From a970a579b20058a1c6cb95cbedf962114a579b83 Mon Sep 17 00:00:00 2001
From: Wenzel Jakob <wenzel.jakob@epfl.ch>
Date: Fri, 20 May 2016 12:00:56 +0200
Subject: [PATCH] eigen.h: return compile time vectors as 1D NumPy arrays

---
 include/pybind11/eigen.h | 53 ++++++++++++++++++++++++++--------------
 1 file changed, 35 insertions(+), 18 deletions(-)

diff --git a/include/pybind11/eigen.h b/include/pybind11/eigen.h
index 746f0a2f7..00f0347a8 100644
--- a/include/pybind11/eigen.h
+++ b/include/pybind11/eigen.h
@@ -41,6 +41,7 @@ template<typename Type>
 struct type_caster<Type, typename std::enable_if<is_eigen_dense<Type>::value>::type> {
     typedef typename Type::Scalar Scalar;
     static constexpr bool rowMajor = Type::Flags & Eigen::RowMajorBit;
+    static constexpr bool isVector = Type::IsVectorAtCompileTime;
 
     bool load(handle src, bool) {
        array_t<Scalar> buffer(src, true);
@@ -50,7 +51,7 @@ struct type_caster<Type, typename std::enable_if<is_eigen_dense<Type>::value>::t
         buffer_info info = buffer.request();
         if (info.ndim == 1) {
             typedef Eigen::Stride<Eigen::Dynamic, 0> Strides;
-            if (!Type::IsVectorAtCompileTime &&
+            if (!isVector &&
                 !(Type::RowsAtCompileTime == Eigen::Dynamic &&
                   Type::ColsAtCompileTime == Eigen::Dynamic))
                 return false;
@@ -87,23 +88,39 @@ struct type_caster<Type, typename std::enable_if<is_eigen_dense<Type>::value>::t
     }
 
     static handle cast(const Type &src, return_value_policy /* policy */, handle /* parent */) {
-        array result(buffer_info(
-            /* Pointer to buffer */
-            const_cast<Scalar *>(src.data()),
-            /* Size of one scalar */
-            sizeof(Scalar),
-            /* Python struct-style format descriptor */
-            format_descriptor<Scalar>::value,
-            /* Number of dimensions */
-            2,
-            /* Buffer dimensions */
-            { (size_t) src.rows(),
-              (size_t) src.cols() },
-            /* Strides (in bytes) for each index */
-            { sizeof(Scalar) * (rowMajor ? src.cols() : 1),
-              sizeof(Scalar) * (rowMajor ? 1 : src.rows()) }
-        ));
-        return result.release();
+        if (isVector) {
+            return array(buffer_info(
+                /* Pointer to buffer */
+                const_cast<Scalar *>(src.data()),
+                /* Size of one scalar */
+                sizeof(Scalar),
+                /* Python struct-style format descriptor */
+                format_descriptor<Scalar>::value,
+                /* Number of dimensions */
+                1,
+                /* Buffer dimensions */
+                { (size_t) src.size() },
+                /* Strides (in bytes) for each index */
+                { sizeof(Scalar) }
+            )).release();
+        } else {
+            return array(buffer_info(
+                /* Pointer to buffer */
+                const_cast<Scalar *>(src.data()),
+                /* Size of one scalar */
+                sizeof(Scalar),
+                /* Python struct-style format descriptor */
+                format_descriptor<Scalar>::value,
+                /* Number of dimensions */
+                isVector ? 1 : 2,
+                /* Buffer dimensions */
+                { (size_t) src.rows(),
+                  (size_t) src.cols() },
+                /* Strides (in bytes) for each index */
+                { sizeof(Scalar) * (rowMajor ? src.cols() : 1),
+                  sizeof(Scalar) * (rowMajor ? 1 : src.rows()) }
+            )).release();
+        }
     }
 
     template <typename _T> using cast_op_type = pybind11::detail::cast_op_type<_T>;