Add begin() and end() to Box.

opm/parser/eclipse/EclipseState/Grid/Box.cpp

@@ -103,6 +103,16 @@ namespace Opm {
     }
 
 
+
+    std::vector<size_t>::const_iterator Box::begin() const {
+        return m_indexList.begin();
+    }
+
+    std::vector<size_t>::const_iterator Box::end() const {
+        return m_indexList.end();
+    }
+
+
     const std::vector<size_t>& Box::getIndexList() const {
         return m_indexList;
     }

opm/parser/eclipse/EclipseState/Grid/Box.hpp

@@ -38,7 +38,8 @@ namespace Opm {
         bool equal(const Box& other) const;
 
         explicit operator bool() const;
-
+        std::vector<size_t>::const_iterator begin() const;
+        std::vector<size_t>::const_iterator end() const;
 
     private:
         void initIndexList();

opm/parser/eclipse/EclipseState/Grid/tests/BoxTests.cpp

@@ -53,10 +53,16 @@ BOOST_AUTO_TEST_CASE(CreateBox) {
                 for (i=0; i < box.getDim(0); i++) {
                     size_t g = i + j*box.getDim(0) + k*box.getDim(0)*box.getDim(1);
                     BOOST_CHECK_EQUAL( indexList[g] , g);
-
+                    
                 }
             }
         }
+
+        i = 0;
+        for (auto index : box) {
+            BOOST_CHECK_EQUAL( index , indexList[i]);
+            i++;
+        }
     }
 }