Missing includes and const for Euclidean_distance.

git-svn-id: svn+ssh://scm.gforge.inria.fr/svnroot/gudhi/trunk@2158 636b058d-ea47-450e-bf9e-a15bfbe3eedb

Former-commit-id: 9f2243ec5c2a50b271031b6b8c8148afeb0bc1df

1 files changed, 3 insertions, 1 deletions

diff --git a/src/common/include/gudhi/distance_functions.h b/src/common/include/gudhi/distance_functions.h
index 5891ef0e..7bf97c23 100644
--- a/src/common/include/gudhi/distance_functions.h
+++ b/src/common/include/gudhi/distance_functions.h
@@ -24,6 +24,8 @@
 #define DISTANCE_FUNCTIONS_H_
 
 #include <cmath>  // for std::sqrt
+#include <type_traits> // for std::decay
+#include <iterator> // for std::begin, std::end
 
 /** @file
  * @brief Global distance functions
@@ -34,7 +36,7 @@
 class Euclidean_distance {
  public:
   template< typename Point >
-  auto operator()(const Point& p1, const Point& p2) -> typename std::decay<decltype(*std::begin(p1))>::type {
+  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.;