From 95cbbd98a9b1dcec7142f1b45555991cf0f94b70 Mon Sep 17 00:00:00 2001
From: glisse <glisse@636b058d-ea47-450e-bf9e-a15bfbe3eedb>
Date: Fri, 22 Dec 2017 14:18:50 +0000
Subject: Cleanups in Euclidean_distance.

git-svn-id: svn+ssh://scm.gforge.inria.fr/svnroot/gudhi/branches/misc-glisse@3102 636b058d-ea47-450e-bf9e-a15bfbe3eedb

Former-commit-id: 06a14b11149e9c7265b8a3427404a9a0991d51aa
---
 src/common/include/gudhi/distance_functions.h | 31 +++++++++++++++++++--------
 1 file changed, 22 insertions(+), 9 deletions(-)

(limited to 'src/common/include')

diff --git a/src/common/include/gudhi/distance_functions.h b/src/common/include/gudhi/distance_functions.h
index c556155e..3a5d1fd5 100644
--- a/src/common/include/gudhi/distance_functions.h
+++ b/src/common/include/gudhi/distance_functions.h
@@ -23,6 +23,10 @@
 #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
@@ -38,20 +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) {
-    return  sqrt((f.first-s.first)*(f.first-s.first) + (f.second-s.second)*(f.second-s.second));
+  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);
   }
 };
 
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