1 files changed, 25 insertions, 7 deletions

diff --git a/include/gudhi/distance_functions.h b/include/gudhi/distance_functions.h
index f6e2ab5a..3a5d1fd5 100644
--- a/include/gudhi/distance_functions.h
+++ b/include/gudhi/distance_functions.h
@@ -23,9 +23,14 @@
 #ifndef DISTANCE_FUNCTIONS_H_
 #define DISTANCE_FUNCTIONS_H_
 
+#include <gudhi/Debug_utils.h>
+
+#include <boost/range/metafunctions.hpp>
+
 #include <cmath>  // for std::sqrt
 #include <type_traits>  // for std::decay
 #include <iterator>  // for std::begin, std::end
+#include <utility>
 
 namespace Gudhi {
 
@@ -37,16 +42,29 @@ namespace Gudhi {
  * have the same dimension. */
 class Euclidean_distance {
  public:
+  // boost::range_value is not SFINAE-friendly so we cannot use it in the return type
   template< typename Point >
-  auto operator()(const Point& p1, const Point& p2) const -> typename std::decay<decltype(*std::begin(p1))>::type {
-    auto it1 = p1.begin();
-    auto it2 = p2.begin();
-    typename Point::value_type dist = 0.;
-    for (; it1 != p1.end(); ++it1, ++it2) {
-      typename Point::value_type tmp = (*it1) - (*it2);
+  typename std::iterator_traits<typename boost::range_iterator<Point>::type>::value_type
+  operator()(const Point& p1, const Point& p2) const {
+    auto it1 = std::begin(p1);
+    auto it2 = std::begin(p2);
+    typedef typename boost::range_value<Point>::type NT;
+    NT dist = 0;
+    for (; it1 != std::end(p1); ++it1, ++it2) {
+      GUDHI_CHECK(it2 != std::end(p2), "inconsistent point dimensions");
+      NT tmp = *it1 - *it2;
       dist += tmp*tmp;
     }
-    return std::sqrt(dist);
+    GUDHI_CHECK(it2 == std::end(p2), "inconsistent point dimensions");
+    using std::sqrt;
+    return sqrt(dist);
+  }
+  template< typename T >
+  T operator() (const std::pair< T, T >& f, const std::pair< T, T >& s) const {
+    T dx = f.first - s.first;
+    T dy = f.second - s.second;
+    using std::sqrt;
+    return sqrt(dx*dx + dy*dy);
   }
 };