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diff --git a/include/gudhi/Active_witness/Active_witness_iterator.h b/include/gudhi/Active_witness/Active_witness_iterator.h
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+++ b/include/gudhi/Active_witness/Active_witness_iterator.h
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+/*    This file is part of the Gudhi Library. The Gudhi library
+ *    (Geometric Understanding in Higher Dimensions) is a generic C++
+ *    library for computational topology.
+ *
+ *    Author(s):       Siargey Kachanovich
+ *
+ *    Copyright (C) 2016  INRIA (France)
+ *
+ *    This program is free software: you can redistribute it and/or modify
+ *    it under the terms of the GNU General Public License as published by
+ *    the Free Software Foundation, either version 3 of the License, or
+ *    (at your option) any later version.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU General Public License for more details.
+ *
+ *    You should have received a copy of the GNU General Public License
+ *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef ACTIVE_WITNESS_ACTIVE_WITNESS_ITERATOR_H_
+#define ACTIVE_WITNESS_ACTIVE_WITNESS_ITERATOR_H_
+
+#include <boost/iterator/iterator_facade.hpp>
+#include <list>
+
+namespace Gudhi {
+
+namespace witness_complex {
+
+/* \brief Iterator in the nearest landmark list.
+ *  \details After the iterator reaches the end of the list,
+ *          the list is augmented by a (nearest landmark, distance) pair if possible.
+ *          If all the landmarks are present in the list, iterator returns the specific end value
+ *          of the corresponding 'Active_witness' object.
+ */
+template< typename Active_witness,
+          typename Id_distance_pair,
+          typename INS_iterator >
+class Active_witness_iterator
+  : public boost::iterator_facade< Active_witness_iterator <Active_witness, Id_distance_pair, INS_iterator>,
+                                   Id_distance_pair const,
+                                   boost::forward_traversal_tag,
+                                   Id_distance_pair const> {
+  friend class boost::iterator_core_access;
+
+  typedef typename std::list<Id_distance_pair>::iterator Pair_iterator;
+  typedef typename Gudhi::witness_complex::Active_witness_iterator<Active_witness,
+                                                                   Id_distance_pair,
+                                                                   INS_iterator> Iterator;
+
+  Active_witness *aw_;
+  Pair_iterator lh_;  // landmark handle
+  bool is_end_;  // true only if the pointer is end and there are no more neighbors to add
+
+ public:
+  Active_witness_iterator(Active_witness* aw)
+    : aw_(aw), lh_(aw_->nearest_landmark_table_.end()), is_end_(true) {
+  }
+
+  Active_witness_iterator(Active_witness* aw, const Pair_iterator& lh)
+    : aw_(aw), lh_(lh) {
+    is_end_ = false;
+    if (lh_ == aw_->nearest_landmark_table_.end()) {
+      if (aw_->iterator_next_ == aw_->iterator_end_) {
+        is_end_ = true;
+      } else {
+        aw_->nearest_landmark_table_.push_back(*aw_->iterator_next_);
+        lh_ = --aw_->nearest_landmark_table_.end();
+        ++(aw_->iterator_next_);
+      }
+    }
+  }
+
+ private :
+  Id_distance_pair& dereference() const {
+    return *lh_;
+  }
+
+  bool equal(const Iterator& other) const {
+    return (is_end_ == other.is_end_) || (lh_ == other.lh_);
+  }
+
+  void increment() {
+    // the neighbor search can't be at the end iterator of a list
+    GUDHI_CHECK(!is_end_ && lh_ != aw_->nearest_landmark_table_.end(),
+                std::logic_error("Wrong active witness increment."));
+    // if the id of the current landmark is the same as the last one
+
+    lh_++;
+    if (lh_ == aw_->nearest_landmark_table_.end()) {
+      if (aw_->iterator_next_ == aw_->iterator_end_) {
+        is_end_ = true;
+      } else {
+        aw_->nearest_landmark_table_.push_back(*aw_->iterator_next_);
+        lh_ = std::prev(aw_->nearest_landmark_table_.end());
+        ++(aw_->iterator_next_);
+      }
+    }
+  }
+};
+
+}  // namespace witness_complex
+}  // namespace Gudhi
+
+#endif  // ACTIVE_WITNESS_ACTIVE_WITNESS_ITERATOR_H_