Added EIGEN_DEFINE_STL_VECTOR_SPECIALIZATION macro including unit tests and documentation.

Eigen/StdVector

@@ -29,6 +29,45 @@
 #include "Core"
 #include <vector>
 
+// Define the explicit instantiation (e.g. necessary for the Intel compiler)
+#if defined(__INTEL_COMPILER) || defined(__GNUC__)
+  #define EIGEN_EXPLICIT_STL_VECTOR_INSTANTIATION(...) template class std::vector<__VA_ARGS__, Eigen::aligned_allocator<__VA_ARGS__> >;
+#else
+  #define EIGEN_EXPLICIT_STL_VECTOR_INSTANTIATION(...)
+#endif
+
+/**
+ * This section contains a convenience MACRO which allows an easy specialization of
+ * std::vector such that for data types with alignment issues the correct allocator
+ * is used automatically.
+ */
+#define EIGEN_DEFINE_STL_VECTOR_SPECIALIZATION(...) \
+EIGEN_EXPLICIT_STL_VECTOR_INSTANTIATION(__VA_ARGS__) \
+namespace std \
+{ \
+  template<typename _Ay> \
+  class vector<__VA_ARGS__, _Ay>  \
+    : public vector<__VA_ARGS__, Eigen::aligned_allocator<__VA_ARGS__> > \
+  { \
+    typedef vector<__VA_ARGS__, Eigen::aligned_allocator<__VA_ARGS__> > vector_base; \
+  public: \
+    typedef __VA_ARGS__ value_type; \
+    typedef typename vector_base::allocator_type allocator_type; \
+    typedef typename vector_base::size_type size_type;  \
+    typedef typename vector_base::iterator iterator;  \
+    explicit vector(const allocator_type& a = allocator_type()) : vector_base(a) {}  \
+    template<typename InputIterator> \
+    vector(InputIterator first, InputIterator last, const allocator_type& a = allocator_type()) : vector_base(first, last, a) {} \
+    vector(const vector& c) : vector_base(c) {}  \
+    explicit vector(size_type num, const value_type& val = value_type()) : vector_base(num, val) {} \
+    vector(iterator start, iterator end) : vector_base(start, end) {}  \
+    vector& operator=(const vector& x) {  \
+      vector_base::operator=(x);  \
+      return *this;  \
+    } \
+  }; \
+}
+
 namespace Eigen {
 
 // This one is needed to prevent reimplementing the whole std::vector.