Use beforeBegin() and beforeEnd()

dune/matrix-vector/triangularsolve.hh

@@ -3,30 +3,6 @@
 
 namespace Dune {
 namespace MatrixVector {
-  // From http://stackoverflow.com/a/28139075/179927
-  // Note: free rbegin()/rend() still missing gcc 4.9.x version of libstdc++
-  namespace {
-    template <typename T>
-    struct reversion_wrapper {
-      T& iterable;
-    };
-
-    template <typename T>
-    auto begin(reversion_wrapper<T> w) {
-      return w.iterable.rbegin();
-    }
-
-    template <typename T>
-    auto end(reversion_wrapper<T> w) {
-      return w.iterable.rend();
-    }
-
-    template <typename T>
-    reversion_wrapper<T> reverse(T&& iterable) {
-      return {iterable};
-    }
-  }
-
   template <class Matrix, class Vector, class BitVector>
   static void lowerTriangularSolve(Matrix const& A, Vector const& b, Vector& x,
                                    BitVector const* ignore,
@@ -62,11 +38,7 @@ namespace MatrixVector {
     if (transpose) {
       // TODO: not yet handled
     } else {
-      std::vector<typename Matrix::ConstIterator> rows(U.N());
-      for (auto it = U.begin(); it != U.end(); ++it)
-        rows[it.index()] = it;
-
-      for (auto it : reverse(rows)) {
+      for (auto it = U.beforeEnd(); it != U.beforeBegin(); --it) {
         size_t i = it.index();
         if (ignore != nullptr and (*ignore)[i].all())
           continue;